JPH05213663A - Binder for producing inorganic sintered compact - Google Patents

Abstract

PURPOSE:To obtain a binder which is not carbonized even by heating in a nonoxidizing atmosphere by using methacrylate polymers contg. specified methacrylates as monomeric units and specifying the content of polymers within a specified mol.wt. range and the ratio between polymers on the low mol.wt. side and polymers on the high mol.wt. side. CONSTITUTION:This binder consists of methacrylate polymers contg. >=90wt.% methacrylate units of butyl methacrylate, a methacrylate contg. a cycloalkyl group, methacrylate contg. a hydroxyl group or a methacrylate having >=8C alkyl side chain at the beta-position and having >=70wt.% content of isobutyl methacrylate units, 10,000-60,000 number average mol.wt. and 0.1-10 acid value. In this binder, polymers having 1,000-1,000,000 mol.wt. account for >=90wt.% of the total amt. and the weight ratio between polymers having <=150,000 mol.wt. and polymers having >150,000 mol.wt. is (1:1)-(5:1).

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. Easily decomposes even under sintering conditions in oxidizing atmosphere
The present invention relates to a binder that is scattered and does not remain as an 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. In this method, a green molded body is fired, the binder is decomposed and scattered, and the ceramic powder is sintered.

In this case, since the sintering is usually carried out in an oxidizing gas atmosphere such as in air, the organic binder is thermally decomposed and burned off, and undecomposed / unburned carbide is hardly left inside the sintered body. In addition, since the inorganic fine powder is sintered and solidified after the binder is burned off, a dense sintered compact having almost no void defects can be obtained.

However, depending on the type of the inorganic powder or the use of the sintered compact, it may be necessary to perform firing / sintering in a non-oxidizing atmosphere. For example, if the inorganic fine powder contains nitrides, carbides, metals, etc., firing and sintering in an oxidizing atmosphere will oxidize them and lose their properties as a non-oxide sintered body. Must be sintered. In addition, we would like to form a film made of non-oxide material on the surface of compacts such as ceramics and ceramic green compacts, and fire 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 compact molded with an organic polymer binder is heated in a non-oxidizing atmosphere, some of the organic polymer binder does not decompose and scatter and easily remains as a carbide in the sintered body, which is why it is burned. Cracks, warpage, swelling, etc. occur in the compact during the binding process, and a large amount of carbide remains in the sintered compact, which reduces the compactness, weakens the sintered compact, and reduces electrical insulation. Or cause various problems such as coloring from gray to black.

[0005]

The present invention has been made in view of the above circumstances, and its purpose is to effectively perform a function as a binder in a molding process of a green molded body and to obtain excellent molding. In addition to exhibiting good shape and shape retention property, it is easy to decompose and scatter during sintering, not only when heat-sintering in an oxidizing atmosphere but also when heat-sintering in a non-oxidizing atmosphere. It is intended to provide a binder for producing an inorganic sintered body that does not remain as a carbide in the sintered compact.

[0006]

The composition of the binder according to the present invention, which has been able to achieve the above object, comprises butyl methacrylate, a cycloalkyl group-containing methacrylate, a hydroxyl group-containing methacrylate and a C8 or more alkyl side chain at the β-position. A methacrylate unit selected from the group consisting of methacrylates occupies 90% by weight or more of the whole, and is made of a methacrylate polymer having an isobutyl methacrylate unit content of 70% by weight or more, and has a molecular weight of 1,000 to 1,000,000. Where the content of the polymer accounts for 90% by weight or more and the content ratio of the polymer having a molecular weight of 150,000 or less and the polymer having a molecular weight of more than 150,000 in the molecular weight range is 1/1 to 5/1. It has a gist.

The molecular weight in the present invention was measured by the following method. Measuring device: WATERS gel permeation chromatography "M-410" Detector: Differential refractometer Used column: WATERS ultra stylajuru (diameter 7.8 mm x 300 mm) x 4 Standard substance: polystyrene Measuring conditions : Flow rate 1cc / min (THF) Temperature 40 ℃

In the above, n-butyl methacrylate, isobutyl methacrylate, secondary butyl methacrylate, tertiary butyl methacrylate, cyclohexyl methacrylate and 2-hydroxy are particularly preferred among the main monomer units constituting the methacrylate polymer. A methacrylate-based polymer in which at least one selected from the group consisting of ethyl methacrylate, 2-hydroxypropyl methacrylate, and 2-ethylhexyl methacrylate accounts for 90% by weight or more of the whole, and isobutyl methacrylate units account for 70% by weight or more of the whole. And is most easily and promptly decomposed and scattered in the firing / sintering process under a non-oxidizing atmosphere. The methacrylate polymer preferably has an acid value of 0.1 to 10 from the viewpoint of ensuring the dispersibility and moldability of the inorganic powder during the production of the green molded body, and the number average molecular weight of the green molded body is 1 The use of those in the range of 10,000 to 60,000 can further improve the moldability, shape retention and decomposition / scattering property during sintering.

[0009]

As described above, according to the present invention, the content of a methacrylate polymer containing a selected methacrylate as a main monomer unit and having a specific molecular weight range is specified, and a molecular weight of 150,000 is selected within the molecular weight range. As a standard, the content ratio of the low molecular weight side polymer and the high molecular weight side polymer is specified, and these setting criteria are the original required characteristics as a binder for producing a green molded body containing an inorganic powder. While ensuring the
The reason is set in order to ensure the characteristics that can be easily decomposed and scattered even during sintering in a non-oxidizing atmosphere, and the reasons for setting each constituent element will be described in detail below.

First, butyl methacrylate, a cycloalkyl group-containing methacrylate, a hydroxyl group-containing methacrylate and a methacrylate having an alkyl side chain of C8 or more at the β-position are selected as the main monomer units of the methacrylate polymer because these are used as monomer units. The polymer containing is easily depolymerized and easily depolymerizes and scatters even when heated in a non-oxidizing atmosphere,
This is because it is difficult for the carbide to remain in the sintered body.

Here, as butyl acrylate, n-butyl methacrylate, isobutyl methacrylate, second
Examples thereof include tertiary butyl methacrylate and tertiary butyl methacrylate, and among these, isobutyl acrylate is the most preferable of all the methacrylate monomers including the methacrylates shown below. Specific examples of the cycloalkyl group-containing methacrylate include cyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate and the like, and of these, cyclohexyl methacrylate is particularly preferable. Specific examples of the hydroxyl group-containing methacrylate include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, glycerol monomethacrylate, trimethylolpropane monomethacrylate, polyethylene glycol monomethacrylate, and polypropylene. Glycol monomethacrylate and the like can be mentioned, but among these, 2-hydroxyethyl methacrylate and 2-hydroxyethyl methacrylate are particularly preferable.
It is hydroxypropyl methacrylate. Specific examples of the methacrylate having a C8 or higher alkyl side chain at the β-position include 2-ethylhexyl methacrylate, isooctyl methacrylate, isodecyl methacrylate,
Isolauryl methacrylate, isostearyl methacrylate and the like are exemplified, but among these, 2-ethylhexyl methacrylate is particularly preferable.

To achieve the object of the present invention, at least one selected from the group consisting of the above-mentioned methacrylates.
The seed occupies 90% by weight or more, more preferably 95% by weight or more of all the monomer units, and isobutyl methacrylate showing particularly excellent depolymerizability among the methacrylates is 70% by weight or more, and more preferably 80% by weight. A methacrylate-based polymer that occupies the above must be used, and if these requirements are lacking, 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, all or most of the monomer units are preferably the above-mentioned methacrylate units, and they may be homopolymers, or copolymers using two or more kinds of monomers. It doesn't matter.

In the present invention, a small amount of another copolymerizable monomer may be copolymerized as long as the content of the methacrylate unit is satisfied, and such a copolymerizable monomer may be methyl (meth). Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl acrylate, isobutyl acrylate, 2
-(Meth) acrylate-based monomers such as methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate and dimethylamino (meth) acrylate; styrene, α-methylstyrene, Styrene-based monomers such as β-methylstyrene, α-ethylstyrene, β-ethylstyrene, vinylstyrene; acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, maleic acid monoester (monoisopropyl maleate, etc.), etc. A copolymerizable unsaturated carboxylic acid of; further (meth) acrylonitrile, acrylamide, vinyl acetate,
Vinyl chloride and the like are exemplified, and if necessary, two or more kinds can be used in combination. Among these copolymerizable monomers, the copolymerizable unsaturated carboxylic acid has a function of giving an appropriate acid value to the methacrylate polymer to enhance the dispersibility and dispersion stability of the inorganic powder. Therefore, the combined use of a small amount of copolymerizable unsaturated carboxylic acid is desirable in the present invention. Methacrylic acid is particularly preferred among the copolymerizable unsaturated carboxylic acids.

In the methacrylate polymer constituting the binder of the present invention, the molecular weight is a very important requirement in addition to the constituent requirements of the above-mentioned monomer unit, and the function as a binder (in particular, the moldability and shape retention of the green molded body). Sex)
In order to ensure the decomposition and scattering during sintering while effectively achieving the above, the content of the polymer having a molecular weight in the range of 1,000 to 1,000,000 determined by the above method is 90% by weight or more, It preferably accounts for 95% by weight or more, and the content ratio of the polymer having a molecular weight of 150,000 or less and the polymer having a molecular weight of more than 150,000 in the molecular weight range is 1 / by weight.
It should be in the range of 1-5 / 1, more preferably 2 / 1-4 / 1.

However, when the proportion of low molecular weight substances and high molecular weight substances outside the above molecular weight range exceeds 10% by weight,
If there are too many low molecular weight products, the performance as a binder is insufficient and it becomes difficult to obtain satisfactory moldability and shape retention, while if there are too many high molecular weight products, the decomposition / scattering properties during sintering become poor. It becomes worse and the amount of carbides remaining in the sintered compact becomes so large that it cannot be ignored.

Further, even if the content of the polymer within the above preferable molecular weight range satisfies the above requirements, the content ratio of the polymer on the low molecular weight side exceeds the above range based on the molecular weight of 150,000. , The moldability and shape retention of the green molded product are deteriorated. On the other hand, when the content ratio of the polymer on the high molecular weight side exceeds the above range, a large amount remains as a carbide in the sintered molded product.

In the present invention, any object can be achieved as long as it satisfies the two requirements of the content rate of the monomer unit and the molecular weight, but the moldability and shape retention of the green molded product and the property at the time of firing can be achieved. In order to further improve the ease of decomposition, the number average molecular weight is 10,000 to 60,000, more preferably 20,000 to 50,000, and the glass transition temperature is 30 to 60.
It is desired to use those having a temperature of 30 ° C, more preferably 30 to 50 ° C.

Further, in order to improve the dispersibility of the inorganic powder and further improve the moldability of the green molded body, it is preferable to give the polymer an appropriate acid value. Therefore, a suitable amount of the copolymerizable unsaturated carboxylic acid is used. As mentioned above, it is preferable to copolymerize However, if the acid value of the copolymer is too high, the decomposition / scattering property during sintering tends to deteriorate, so the acid value is preferably controlled to about 0.1-10. The more preferable acid value of the copolymer varies depending on the type, polarity, acidity, basicity and the like of the inorganic fine powder, and therefore it is desirable to use the one having the optimum acid value according to these.

The polymerization method for obtaining the methacrylate polymer is not limited at all, but the most general method is suspension polymerization in the presence of a radical polymerization initiator such as peroxide, hydroperoxide, azobisisobutyronitrile,
Normal polymerization methods such as solution polymerization and emulsion polymerization are adopted, and usually 5
This is a method of reacting at 0 to 150 ° C. for several minutes to several hours. In this case, a chain transfer agent may be further added during the polymerization reaction, if necessary. The greatest feature of the present invention is that, as described above, the weight ratio of the relatively low molecular weight substance having a molecular weight of 150,000 or less and the relatively high molecular weight substance having a molecular weight of more than 150,000 is specified. A methacrylic polymer having a similar molecular weight structure can be produced as a single polymerization reaction product by controlling the polymerization conditions and the like, and in some cases, a relatively low molecular weight polymer and a high molecular weight polymer can be produced. It is also possible to manufacture them separately and mix them in an appropriate ratio to satisfy the above-mentioned molecular weight constitution.

The kind of the inorganic powder used in combination with the binder made of the methacrylic polymer is not limited at all, and oxides such as alumina, titania, silica, magnesia, zirconia, mullite, cordierite, zircon and titanic acid are used. Of course, it can be used as a binder for one or more oxide-based ceramic powders such as barium, zircon, lead titanate, and aluminum titanate, which can be baked and sintered in an oxidizing atmosphere without any problem. However, the feature of the binder of the present invention is most effectively exerted when an inorganic powder, such as aluminum nitride, silicon nitride, or boron nitride, which undergoes oxidative deterioration when fired / sintered in an oxidizing atmosphere is used. Nitride; Carbides such as silicon carbide, tungsten carbide, boron carbide; stainless steel, stellite 1, such as a metal such as titanium aluminum alloy
It is a powder of at least one kind. Depending on the type of sintering raw material, even if a small amount of oxygen is present in the firing / sintering atmosphere, there is no substantial adverse effect, so when using it in combination with such an inorganic powder, It does not matter if the sintering atmosphere contains a small amount of oxygen or water.

The method for producing an inorganic sintered compact using the binder of the present invention is not particularly special and may be carried out by 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, isopropyl alcohol, butanol, ethyl acetate, toluene and xylene, alone or as a mixture).
The amount of the binder used may be determined appropriately, but the moldability, the shape retention of the green compact, and the decomposition / decomposition during sintering.
Inorganic powder 100 is the most common in consideration of scattering.
It is in the range of 5 to 40 parts by weight with respect to parts by weight. At this time, if necessary, a dispersant (polyhydric alcohol ester such as glycerin or sorbitan, or an amine dispersant), a plasticizer (polyethylene glycol, dibutyl phthalate, dioctyl phthalate, etc.) for imparting plasticity to the green molded body, or It is also possible to mix an appropriate amount of 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, but this molding method is not limited at all, and press molding, injection molding, extrusion molding, doctor blade method, etc. are conventionally used. Any method known from Next, this green compact is heat-treated to volatilize and remove the dispersion medium, decompose and disperse the binder, and sinter. However, if the heat treatment temperature is raised to the sintering temperature all at once, cracks or void defects will occur in the compact. Because it ’s easier to do
It is preferable that the temperature is gradually increased stepwise or continuously so that the volatilization of the dispersion medium and the dispersion / scattering of the binder are completed in a relatively low temperature range before sintering.

[0023]

EFFECTS OF THE INVENTION The present invention is constituted as described above, and has characteristics that it retains various functions as a binder and is easily decomposed and scattered without being carbonized even when heated in a non-oxidizing atmosphere. 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 as a carbide in the sintered compact to deteriorate the appearance and reduce the sintered density. In addition, depending on the application, it is necessary to impart various properties such as insulating properties, electrical conductivity, and magnetic properties to the sintered compact, and these required properties may be significantly impaired by the remaining carbides. You can avoid such problems by using it. Further, since the binder of the present invention is easily decomposed and burned down even under firing / sintering conditions in an oxidizing atmosphere, it can be used as a binder for an inorganic powder which is fired / sintered in an oxidizing atmosphere without any trouble.

[0024]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and may be modified appropriately in accordance with the spirit of the preceding and following description. All implementations are within the scope of the invention.

Examples 1 to 11 and Comparative Examples 1 to 7 120 parts by weight of toluene as a solvent was placed in a separable flask equipped with a stirrer, a thermometer, a nitrogen introducing tube, a monomer dropping funnel and a polymerization initiator dropping funnel. The inside of the flask is replaced with nitrogen by blowing nitrogen through the nitrogen introducing pipe. The monomer dropping funnel is charged with 100 parts by weight of the monomer 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. Then place the flask at 60 ° C.
The temperature is raised to 1, the monomer and the polymerization initiator are added dropwise over 2 hours while stirring at the same temperature, and the stirring is continued for another 2 hours at the same temperature, then the internal temperature is increased to 80 ° C and the heating is continued for another 2 hours. After stirring, the temperature was lowered by cooling to obtain a methacrylate polymer.

The molecular weight distribution of each of the obtained polymers was measured by the above-mentioned method, and the content of those having a molecular weight of 1,000 to 1,000,000 and the molecular weight (1,000 to 150,000) / (150,000 to 100).
The weight ratio, the number average molecular weight, the gas transition temperature (Tg) and the acid value were determined, and the results are also shown in Table 1. 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 2 hours, and the presence or absence thereof is also shown in Table 1.
The thermal decomposability of each of the obtained polymers was measured by a thermobalance (measurement condition: in a nitrogen stream of 4 liter / min, the temperature was raised to 600 ° C. at a heating rate of 3 ° C./min), and the respective thermal decomposition curves were obtained. I asked. As a representative example of the results, the thermal decomposition curves of Example 1 and Comparative Examples 2 and 3 are shown in FIG.

The meanings of the symbols in Table 1 are as follows. i-BMA: isobutyl methacrylate MMA: methacrylic acid AA: acrylic acid n-BMA: n-butyl methacrylate sec-BMA: secondary butyl methacrylate t-BMA: tertiary butyl methacrylate CHMA: cyclohexyl methacrylate 2-HEMA: 2- Hydroxyethyl methacrylate 2-HPMA: 2-hydroxypropyl methacrylate 2-EHMA: 2-ethylhexyl methacrylate EA: ethyl acrylate

[0028]

[Table 1]

Test Example 1 100 parts by weight of a mixed powder of 45% by weight of aluminum oxide fine powder having an average particle diameter of 15 μm and 55% by weight of borosilicate glass powder having an average particle diameter of 20 μm, and the methacrylate-based copolymer weight obtained in Example 1 15 parts by weight of the combined material as a binder, 3 parts by weight of dioctyl phthalate as a plasticizer, and a mixed solvent of toluene / methyl ethyl ketone (1/1) 50 as a solvent.
After mixing parts by weight to form a slurry, a 0.3 mm thick alumina / glass green sheet was obtained by the doctor blade method.

This green sheet was heated at 600 ° C. in a nitrogen stream.
After heating for 2 hours to remove the binder, the material was held at 900 ° C. for 1 hour for firing and sintering. The residual carbon content of the obtained sintered sheet was extremely low at 30 ppm, and the bending strength was 180.
It was very excellent at 0 kg / cm ² . The green sheet was heated in air at 500 ° C. for 1 hour to remove the binder, and then held at 900 ° C. for 1 hour to be fired / sintered, and the residual carbon content of the obtained sintered sheet was 10 ppm or less.
The bending strength was 1800 kg / cm ² .

Test Example 2 An alumina / glass green sheet was obtained in the same manner as in Test Example 1 except that 12 parts by weight of the methacrylate polymer obtained in Example 8 was used as a binder. Similar to Test Example 1, this green sheet was debindered, fired and sintered in a nitrogen stream to obtain a sintered sheet. The obtained sintered sheet had a residual carbon content of 40 ppm and a bending strength of 2
It was 000 kg / cm ² .

Comparative Test Example 1 Alumina / glass green sheets were molded and degassed in a nitrogen stream in the same manner as in Test Example 1 except that 18 parts by weight of the methacrylate polymer obtained in Comparative Example 4 was used as a binder. A binder and a binder were fired and sintered to obtain a sintered sheet. The residual carbon content of this sintered sheet was as low as 50 ppm, but the bending strength was 950 kg / cm ^2, which was very weak.

Comparative Test Example 2 Alumina / glass green sheets were molded and degassed in a nitrogen stream in the same manner as in Test Example 1 except that 16 parts by weight of the methacrylate polymer obtained in Comparative Example 2 was used as a binder. A binder and a binder were fired and sintered to obtain a sintered sheet. The residual carbon content of the sintered sheet was 450 ppm, the sheet was gray, and the bending strength was 1100.
It was kg / cm ² .

Test Example 3 The methacrylate copolymer obtained in Example 7 was added to 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. A slurry was prepared by mixing 5 parts by weight as a binder and 40 parts by weight of methyl ethyl ketone as a solvent.

The obtained slurry was dried by an alumina sieving machine, and the dried powder was press-molded into a cylindrical shape having a diameter of 10 mm and a height of 10 mm to prepare a block molded body (green body). The green body was heated at 600 ° C. for 2 hours in a nitrogen atmosphere to remove the binder, and then heated to 1800 ° C. and held for 6 hours to be fired / sintered to obtain an aluminum nitride sintered compact. The relative density of this sintered compact was 99.2%, and the volume resistance was 9 × 10 ¹⁴ Ω · cm.

Comparative Test Example 3 An aluminum nitride sintered compact was obtained in the same manner as in Test Example 3 except that 5 parts by weight of the methacrylate polymer obtained in Comparative Example 5 was used as a binder. When the relative density of this sintered compact is 97.8%, it becomes grayish black and the volume resistance is 4
It was × 10 ¹² Ω · cm.

[Brief description of drawings]

FIG. 1 is a diagram showing a thermal decomposition curve of a methacrylate polymer obtained in an example.

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[Procedure amendment]

[Submission date] June 9, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

The composition of the binder according to the present invention, which has been able to achieve the above object, is butyl methacrylate, cycloalkyl group-containing methacrylate, hydroxyl group-containing methacrylate and C8 or more having an alkyl side chain at the β-position. Methacrylate units selected from the group consisting of methacrylates occupy 90% by weight or more of the whole, and are made of a methacrylate polymer having an isobutyl methacrylate unit content of 70% by weight or more, and have a molecular weight of 1,000 to 1,000,000. Where the content of the polymer accounts for 90% by weight or more and the content ratio of the polymer having a molecular weight of 150,000 or less and the polymer having a molecular weight of more than 150,000 in the molecular weight range is 1/1 to 5/1. It has a gist.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

First, butyl methacrylate, a cycloalkyl group-containing methacrylate, a hydroxyl group-containing methacrylate and a C8 or higher methacrylate having an alkyl side chain at the β-position are selected as the main monomer units of the methacrylate-based polymer. The polymer containing is easily depolymerized and easily depolymerizes and scatters even when heated in a non-oxidizing atmosphere,
This is because it is difficult for the carbide to remain in the sintered body.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Here, as butyl acrylate, n-butyl methacrylate, isobutyl methacrylate, second
Examples include primary butyl methacrylate and tertiary butyl methacrylate, and among these, isobutyl acrylate is the most preferable of all the methacrylate-based monomers including the following methacrylates. Specific examples of the cycloalkyl group-containing methacrylate include cyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate and the like. Of these, cyclohexyl methacrylate is particularly preferable. Specific examples of the hydroxyl group-containing methacrylate include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, glycerol monomethacrylate, trimethylolpropane monomethacrylate, polyethylene glycol monomethacrylate, and polypropylene. Glycol monomethacrylate and the like can be mentioned, but among these, particularly preferable are 2-hydroxyethyl methacrylate and 2-hydroxyethyl methacrylate.
It is hydroxypropyl methacrylate. Specific examples of the C8 or more methacrylate having an alkyl side chain at the β-position include 2-ethylhexyl methacrylate, isooctyl methacrylate, isodecyl methacrylate,
Isolauryl methacrylate, isostearyl methacrylate and the like are exemplified, but among these, 2-ethylhexyl methacrylate is particularly preferable.

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

Claims (3)

[Claims] 1. A methacrylate unit selected from the group consisting of butyl methacrylate, a cycloalkyl group-containing methacrylate, a hydroxyl group-containing methacrylate and a methacrylate having a C8 or more alkyl side chain at the β-position accounts for 90% by weight or more of the whole. , A methacrylate-based polymer having an isobutyl methacrylate unit content of 70% by weight or more, and a molecular weight of 1,000 to 1
The content of the polymer having a molecular weight of, 000,000 accounts for 90% by weight or more, and the content ratio of the polymer having a molecular weight of 150,000 or less and the polymer having a molecular weight of more than 150,000 in the molecular weight range is 1 by weight.
/ 1 to 5/1, A binder for producing an inorganic sintered body, characterized in that 2. A group of methacrylates consisting of n-butyl methacrylate, isobutyl methacrylate, secondary butyl methacrylate, tertiary butyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-ethylhexyl methacrylate. The binder according to claim 1, which is at least one selected from the group consisting of: 3. The binder according to claim 1 or 2, wherein the methacrylate polymer has a number average molecular weight of 10,000 to 60,000 and an acid value of 0.1 to 10.