JP2007106621A - Method for producing aluminum nitride green body - Google Patents

Abstract

An aluminum nitride green body waste material is recycled to obtain a sintered body with good moldability, warping when sintered, small thermal conductivity and small variations in mechanical strength, and less color unevenness. An aluminum nitride green body is provided.
A mixture containing a waste material of an aluminum nitride green body and an organic solvent is subjected to a high-pressure dispersion treatment at a pressure of 50 MPa or more to obtain a regenerated aluminum nitride slurry, and the aluminum nitride slurry including at least a part of the regenerated aluminum nitride slurry. An aluminum nitride green body is produced using the same.
[Selection figure] None

Description

  The present invention relates to a method for producing an aluminum nitride green body.

  The aluminum nitride sintered body can be manufactured by sintering an aluminum nitride green body containing an aluminum nitride powder, a binder and the like. When manufacturing this aluminum nitride sintered body, it is common to cut the aluminum nitride green body into a desired shape and thereafter sinter. The waste material generated by cutting the aluminum nitride green body contains aluminum nitride powder as a raw material for the aluminum nitride sintered body, and can essentially be reused as a raw material for the aluminum nitride sintered body. For example, a waste aluminum nitride green body and a solvent are mixed with a ball mill to form a regenerated aluminum nitride slurry, and a regenerated aluminum nitride green body is produced by removing the solvent from the regenerated aluminum nitride slurry as necessary. It is possible.

  However, when the regenerated aluminum nitride green body obtained by the above-described method is intended to produce a regenerated aluminum nitride green body by increasing the content of the waste aluminum nitride green body with respect to the regenerated aluminum nitride slurry, the regenerated aluminum nitride green body is molded. However, even if the recycled aluminum nitride green body is sintered, the sintered body is likely to be warped and uneven in color, and the thermal conductivity and mechanical strength of the sintered body are greatly varied, which still causes problems. there were.

  An object of the present invention is to recycle waste materials of aluminum nitride green body, have good moldability, warp when sintered, small variation in thermal conductivity and mechanical strength, and a sintered body with little color unevenness An object is to provide an aluminum nitride green body that can be obtained.

  The inventors of the present invention mix a waste material of an aluminum nitride green body and a solvent, and further perform high-pressure dispersion treatment on the mixture containing these to obtain a regenerated aluminum nitride slurry, and the aluminum nitride slurry including at least a part of the regenerated aluminum nitride slurry. It has been found that an aluminum nitride green body can be produced by producing a sintered body with little variation in warpage and physical properties and having little color unevenness when sintered by producing an aluminum nitride green body by removing the solvent from It came to propose an invention.

  That is, the present invention relates to a mixture containing a waste material of aluminum nitride green body and a solvent under high pressure dispersion at a pressure of 50 MPa or more to obtain a regenerated aluminum nitride slurry, and an aluminum nitride slurry containing at least a part of this regenerated aluminum nitride slurry. This is a method for producing an aluminum nitride green body.

  The aluminum nitride green body obtained by the present invention has good appearance with almost no defects such as wrinkles and cracks, and further, by sintering this aluminum nitride green body, warpage, thermal conductivity, and mechanical strength. Thus, an aluminum nitride sintered body with small variations in color and little color unevenness can be obtained.

For the production of the aluminum nitride green body of the present invention, an aluminum nitride slurry containing a regenerated aluminum nitride slurry as at least a part is used.
The regenerated aluminum nitride slurry is obtained by mixing the waste material of the aluminum nitride green body and the organic solvent, and if necessary, aluminum nitride powder, sintering aid, binder, and other additives, followed by high-pressure dispersion treatment. It is done.

First, each raw material of the regenerated aluminum nitride slurry used in the present invention will be described.
[Aluminum nitride green waste]
The waste material of the aluminum nitride green body is generated when the aluminum nitride green body is cut to obtain a desired shape of the obtained aluminum nitride sintered body. The composition of the waste aluminum nitride green body and the composition of the sintered aluminum nitride green body are substantially the same.

Therefore, the waste material of the aluminum nitride green body contains substances contained in the aluminum nitride green body, such as aluminum nitride powder, binders, and other additives.
The aluminum nitride powder is not particularly limited as long as it is an aluminum nitride powder generally contained in an aluminum nitride green body.

  The average particle size of the aluminum nitride powder is not particularly limited as long as an aluminum nitride sintered body is obtained, but is usually in the range of 0.1 μm to 5.0 μm, preferably in the range of 0.5 μm to 3.5 μm. In the present invention, the average particle diameter of the aluminum nitride powder refers to the average particle diameter obtained by the average number of aggregated aluminum nitride particles measured with a laser diffraction particle size distribution analyzer.

  The content of the aluminum nitride powder in the waste material of the aluminum nitride green body is not particularly limited, but is usually 60% by weight to 97% by weight, preferably 70% by weight, based on the total weight of the waste material of the aluminum nitride green body. An amount in the range of -92% by weight.

The binder is not particularly limited as long as it is a binder generally contained in an aluminum nitride green body, but polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, poly 2-ethylhexyl methacrylate, polybutyl methacrylate, polyacrylate Oxygen-containing organic polymers such as cellulose acetate butyrate, nitrocellulose, methylcellulose, hydroxymethylcellulose, polyvinyl alcohol, polyoxyethylene oxide, and polypropylene oxide;
Hydrocarbon organic polymers such as petroleum resin, polyethylene, polypropylene, and polystyrene; other organic polymers such as polyvinyl chloride; wax and the like; or a mixture of two or more of these.

  Among these binders, an oxygen-containing organic polymer is preferably contained. This is because the oxygen-containing organic polymer has an excellent chemical affinity with the aluminum nitride powder, and may be firmly bonded to the aluminum nitride powder.

  When an organic polymer is used as the binder, the number average molecular weight is not particularly limited, but is usually in the range of 3000 to 1000000, preferably 5000 to 300000, in terms of polystyrene. When the number average molecular weight of the organic polymer is in the above range, the green body may have high strength and excellent flexibility.

  The content of these binders in the waste material of the aluminum nitride green body is not particularly limited, but is usually 4 to 30 parts by weight, preferably 5 to 20 parts by weight with respect to 100 parts by weight of the aluminum nitride powder described above. The amount of the part range.

The waste material of the aluminum nitride green body may contain additives such as a sintering aid, a surfactant, and a plasticizer as other components.
As said sintering auxiliary agent, it can use suitably according to the aluminum nitride powder to be used. For example, when the aluminum nitride powder is an aluminum nitride powder, yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (LaO ₃ ), cerium oxide (CeO ₃ ), holmium oxide (HoO ₃ ), ytterbium oxide (Yb ₂ O ₃ ), rare earth compounds such as gadolinium oxide (Gd ₂ O ₃ ), neodymium oxide (NdO ₃ ), samarium oxide (Sm ₂ O ₃ ), dysprosium oxide (Dy ₂ O ₃ ); calcium oxide (CaO), magnesium oxide ( MgO), alkaline earth metal compounds such as strontium oxide (SrO); or mixtures of these compounds can be used.

Among these compounds, yttrium oxide (Y ₂ O ₃ ) is preferably used in order to make the obtained aluminum nitride sintered body dense and further increase the thermal conductivity.
Although there is no restriction | limiting in particular in content of the sintering adjuvant in the waste material of an aluminum nitride green body, Usually 2 to 6 weight part with respect to 100 weight part of aluminum nitride powder mentioned above, Preferably 3 weight part-5 It is an amount in the range of parts by weight.

  The surfactant can be used without particular limitation, but a nonionic surfactant is preferable. Examples of the nonionic surfactant include carboxylated trioxyethylene tridecyl ether, diglycerin monooleate, diglycerin monostearate, carboxylated heptaoxyethylene tridecyl ether, tetraglycerin monooleate, polyoxyethylene sorbitan monooleate, Examples include propylene glycol monostearate, glycerin monostearate, glycerin tristearate, glycerin monooleate, glycerin trioleate, sorbitan trioleate, and sorbitan monooleate, or a mixture of two or more thereof.

  Although there is no restriction | limiting in particular in content of these surfactant in the waste material of an aluminum nitride green body, Usually 0.01 weight part-10 weight part with respect to 100 weight part of aluminum nitride powder mentioned above, Preferably 0.02 is carried out. An amount ranging from parts by weight to 3.0 parts by weight is included.

  The plasticizer can be used without particular limitation, for example, polyethylene glycol and derivatives thereof; phthalates such as dimethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, and dioctyl phthalate; stearates such as butyl stearate Tricresol phosphate; tri-N-butyl phosphate; and glycerin, or a mixture of two or more thereof.

  The content of these plasticizers in the waste material of the aluminum nitride green body is not particularly limited, but is usually 0.1 to 20 parts by weight, preferably 0.4 parts by weight with respect to 100 parts by weight of the aluminum nitride powder described above. Part to 15 parts by weight.

  As long as the performance of the aluminum nitride sintered body is not impaired, other ceramic powders may be included. Examples of these ceramic powders include powders of aluminum oxide, zirconium oxide, titanium oxide, silicon oxide, silicon nitride, barium titanate, ferrite, or a mixture of these compounds. Although there is no restriction | limiting in particular in content of the said other ceramic powder in the waste material of an aluminum nitride green body, Usually, it is 0.1 weight part-5.0 weight part with respect to 100 weight part of aluminum nitride powder mentioned above.

In addition, as described above, the waste material of the aluminum nitride green body is produced by cutting the aluminum nitride green body in order to make the obtained aluminum nitride sintered body into a desired shape. In general, the aluminum green body is filtered, defoamed, desolvated, etc. as necessary from an aluminum nitride slurry obtained by mixing an organic solvent with the above-described aluminum nitride powder, binder, etc., and adjusted in viscosity, etc. And then molded by a sheet molding machine, an extrusion molding machine, an injection molding machine or the like.

Therefore, the organic nitride may be contained in the waste material of the aluminum nitride green body.
The organic solvent is not particularly limited as long as it is generally contained in an aluminum nitride slurry or an aluminum nitride green body,
Ketones such as acetone, methyl ethyl ketone, and methyl isopropyl ketone;
Alcohols such as ethanol, propanol, and butanol;
Aromatic hydrocarbons such as benzene, toluene, and xylene;
Halogenated hydrocarbons such as trichlorethylene, tetrachloroethylene, and bromochloromethane; or mixtures of these organic solvents.

[Organic solvent]
The regenerated aluminum nitride slurry used in the present invention contains an organic solvent.
The organic solvent is not particularly limited as long as it is generally contained in an aluminum nitride slurry that is a raw material for an aluminum nitride sintered body.
Ketones such as acetone, methyl ethyl ketone, and methyl isopropyl ketone;
Alcohols such as ethanol, propanol, and butanol;
Aromatic hydrocarbons such as benzene, toluene, and xylene;
Halogenated hydrocarbons such as trichlorethylene, tetrachloroethylene, and bromochloromethane; or mixtures of these organic solvents.

  The amount of the organic solvent used for the aluminum nitride green body waste is not particularly limited, but is usually in the range of 30 to 300 parts by weight, preferably 50 to 200 parts by weight per 100 parts by weight of the aluminum nitride green waste. The range is parts by weight.

  By setting the blending amount of the organic solvent within the above range, the waste material of the aluminum nitride green body can be completely dissolved when the recycled aluminum nitride slurry is used, and the resulting regenerated aluminum nitride slurry can be easily degassed.

  The organic solvent used in the production of the regenerated aluminum nitride slurry is the same as the solvent remaining in the waste material of the aluminum nitride green body or the organic solvent contained in the aluminum nitride slurry that is the raw material of the aluminum nitride green body. There may be, but it may be different.

[Other ingredients]
The raw material of the regenerated aluminum nitride slurry may further contain other components such as an aluminum nitride powder, a binder, a sintering aid, a surface active agent, a plasticizer, and other ceramic powders as necessary.

  Examples of these aluminum nitride powders, binders, sintering aids, surfactants, plasticizers, and other ceramic powders include the materials described in the section “Aluminum nitride green body waste”.

[Method for producing regenerated aluminum nitride slurry]
The regenerated aluminum nitride slurry used in the present invention produces a mixture containing the waste aluminum nitride green body, the organic solvent, and other components included as necessary, and this mixture is dispersed at high pressure at a pressure of 50 MPa or more. It is obtained by processing.

  The mixture can be obtained by dissolving and mixing the waste material of the aluminum nitride green body, the organic solvent, and other components contained as necessary, by immersing or dissolving with a motor stirrer, a ball mill or the like.

  The apparatus for high-pressure dispersion treatment of this mixture is not particularly limited as long as high-pressure dispersion treatment can be performed at a pressure of 50 MPa or more. For example, a wet jet mill, a penetrating high-pressure dispersion apparatus, a collision-type high-pressure dispersion apparatus, and a porous high-pressure dispersion apparatus , Deburring type high pressure dispersing device, (collision + penetration) type high pressure dispersing device, ultra high pressure homogenizer, and the like.

  In the present invention, for example, using these dispersing devices, the high-pressure dispersion treatment is performed at a pressure of 50 MPa or more, preferably in the range of 100 MPa to 300 MPa, more preferably in the range of 150 MPa to 250 MPa.

  By performing high-pressure dispersion treatment on the mixture at a pressure in the above range, the mixture containing the waste material of the aluminum nitride green body and the organic solvent can be uniformly dispersed, and the regenerated aluminum nitride slurry of the waste material of the aluminum nitride green body The content of the aluminum nitride green body is increased, the problem of deterioration in formability when producing an aluminum nitride green body from an aluminum nitride slurry containing at least a part of the regenerated aluminum nitride, warpage when the aluminum nitride green body is sintered, heat Problems such as variations in conductivity and mechanical strength can be solved.

  If the high-pressure dispersion treatment can be performed so as to satisfy the above conditions, the shape, size, treatment pressure, number of treatments, etc. of the device are not particularly limited. For example, when a collision type high-pressure dispersion device is used, the mixture is usually 50 MPa. The above pressure, preferably in the range of 70 MPa to 300 MPa, more preferably in the range of 100 MPa to 250 MPa, usually 1 to 9 times, preferably 1 to 3 times, more preferably 1 to 2 times, high pressure dispersion By passing through the apparatus, a suitable aluminum nitride slurry can be obtained.

[Method of forming aluminum nitride green body]
The aluminum nitride green body of the present invention can be produced from an aluminum nitride slurry containing at least a part of the regenerated aluminum nitride slurry.

  The aluminum nitride green body can be produced from a regenerated aluminum nitride slurry by the following method, for example. First, the regenerated aluminum nitride slurry is subjected to filter filtration, defoaming, solvent removal, and the like as necessary to adjust the viscosity of the slurry. Thereafter, the viscosity-adjusted slurry is molded by a doctor blade method or the like using a sheet molding machine to obtain a sheet-like molded product.

  In the production of the aluminum nitride green body of the present invention, an aluminum nitride slurry obtained by mixing the regenerated aluminum nitride slurry and a separately prepared normal aluminum nitride slurry can be used as a raw material.

  Here, the normal aluminum nitride slurry is a mixture of raw materials used to obtain a normal aluminum nitride slurry, such as aluminum nitride powder, binder, additive, and organic solvent described in the section “Aluminum nitride waste”. An aluminum nitride slurry obtained by high-pressure dispersion as required.

The content of the aluminum nitride green body as a waste material in the aluminum nitride green body thus obtained is not particularly limited, but is usually 20% by weight to 100% by weight with respect to the total weight of the aluminum nitride green body. %, Preferably in an amount ranging from 30% to 100% by weight. According to the present invention, a sheet having a high content of the waste material of the aluminum nitride green body in the aluminum nitride green body can be easily obtained from the regenerated aluminum nitride slurry whose viscosity is adjusted.

  The content of the organic solvent in the aluminum nitride green body is not particularly limited, but is usually 0.01% to 5% by weight, preferably 0.1% by weight, based on the total weight of the aluminum nitride green body. An amount in the range of ˜2% by weight.

By using the organic solvent in the above range, for example, when an aluminum nitride green body is formed into a sheet shape, the obtained green body has good releasability from the support film.
Further, even when the content of the organic solvent is in the above range, for example, even when the sheet-like aluminum nitride green body is wound into a roll shape and the sheet is deformed, appearance defects such as wrinkles and cracks are hardly observed.

[Degreasing and firing]
A desired aluminum nitride sintered body can be obtained by degreasing and firing the aluminum nitride green body of the present invention obtained as described above.

<Degreasing>
There are no particular restrictions on the degreasing conditions of the aluminum nitride green body, for example, an oxidizing gas such as oxygen or air, a reducing gas such as hydrogen, an inert gas such as argon or nitrogen, carbon dioxide, or a mixed gas atmosphere thereof. Alternatively, it can be carried out in a humidified gas atmosphere in which these gases and water vapor are mixed. Although the degreasing temperature can be appropriately selected depending on the type of binder and the degreasing atmosphere, it can be generally selected from a temperature range of 300 ° C to 1200 ° C, preferably 400 ° C to 1000 ° C. The degreasing time can be appropriately selected according to the type of binder and the degreasing atmosphere, but it can be normally selected from the range of 30 minutes to 10 hours, preferably 2 hours to 8 hours. From the viewpoint of improving the thermal conductivity of the aluminum nitride sintered body obtained from the aluminum nitride green body, the oxygen concentration of the degreased body is adjusted to 3.0% by weight or less by adjusting the degreasing atmosphere, temperature, and degreasing time. It is preferable to make it into the range of 0.9 weight%-2.5 weight%.

<Baking>
The aluminum nitride sintered body is obtained by firing the degreased body obtained by the above degreasing.

  The baking conditions for the degreased body are not particularly limited, but are performed in a non-oxidizing gas atmosphere, under vacuum, or under reduced pressure. As the non-oxidizing gas, for example, a reducing gas such as hydrogen, an inert gas such as argon, helium or nitrogen, or a mixed gas thereof is used. The firing temperature is not particularly limited, but is usually in the range of 1650 ° C to 1900 ° C, preferably 1700 ° C to 1800 ° C, more preferably 1720 ° C to 1790 ° C.

When the firing temperature is in the above range, the aluminum nitride sintered body becomes dense and the crystal grain growth can be in an appropriate range.
In addition to these conditions, the aluminum nitride degreased body may be heat-treated in a non-oxidizing atmosphere at a temperature 10 to 40 ° C. higher than the optimum densification temperature.

The optimum densification temperature refers to a firing temperature at which a sintered body having a relative density with respect to the theoretical density of 99% or more is obtained.
The sintered body obtained under such firing conditions has a high fracture toughness value, and the fracture toughness value, thermal conductivity, and mechanical strength are improved in a well-balanced manner, and variations in mechanical strength are reduced. Further, the dimensional accuracy of the obtained sintered body is improved and the end warp is also reduced.

  The firing time is not particularly limited, but is usually in the range of 2 hours to 20 hours, preferably 5 hours to 15 hours. When the firing time is in the above range, the aluminum nitride sintered body becomes dense and the crystal grain growth can be in an appropriate range, and the fracture toughness value and heat conduction of the obtained aluminum nitride sintered body can be set. The rate and mechanical strength can be improved in a balanced manner.

  When performing the above-described firing, a firing container usually used for firing aluminum nitride can be used without any trouble. For example, an airtight container made of aluminum nitride or nitride shelf can be used.

[Physical properties of sintered aluminum nitride]
The aluminum nitride sintered body thus obtained has little variation in warpage, thermal conductivity, and mechanical strength, and has little color unevenness.

  In particular, when an aluminum nitride green body is produced from the aluminum nitride green body obtained in the present invention, the aluminum nitride green body can be easily formed even if the content of the waste material of the aluminum nitride green body in the recycled aluminum nitride slurry is increased. The shape of the obtained aluminum nitride sintered body is also good because it is difficult to cause shape failure.

[Applications of sintered aluminum nitride]
The aluminum nitride sintered body obtained from the aluminum nitride green body of the present invention can be used for ordinary applications of the aluminum nitride sintered body.
For example, it can be used as it is as a structural material for electronic parts and the like. It can also be used as a metal bonding substrate such as a power module, a circuit substrate having a metallized surface such as a fine pattern, and the like.

  As the metal of the metal bonded substrate, copper, aluminum or the like can be suitably used. Further, the thickness of the metal layer in the metal bonded substrate is usually in the range of 0.1 mm to 1 mm. These metal layers can be bonded to the surface of the aluminum nitride sintered body by the active metal brazing method or other known methods.

〔Example〕
In order to describe the present invention more specifically, examples and comparative examples will be given below, but the present invention is not limited to these examples.

In the following Examples and Comparative Examples, various physical properties were measured by the following methods.
(1) Color unevenness The color unevenness of the sintered body was determined by visual observation and evaluated according to the following criteria.
A: No color unevenness B: Color unevenness (area less than 5%)
C: Color unevenness (area 5% or more, less than 20%)
D: Color irregularity (area 20% or more)
(2) Warpage Place the sintered body on a flat glass substrate, measure the height of the center on both sides of the sintered body using a Mitsutoyo Digimatic Indicator, and the difference between the maximum and minimum values. The average value of 100 sintered bodies was determined.

(3) Fracture toughness value In accordance with JIS R1607, Vickers hardness was measured using a Vickers hardness tester AVK-CO manufactured by Akashi Co., Ltd. From this Vickers hardness, I.V. F. The fracture toughness value was calculated by the method. The indentation load is 49 N and the holding time is 15 seconds. The average value of 10 samples was taken as the measured value.

(4) Mechanical strength In accordance with JIS R1601, a three-point bending strength was measured at a crosshead speed of 0.5 mm / min and a span of 30 mm. The width of the test piece was 4 mm and prepared by surface grinding. The average value and the minimum value of 100 samples were determined.

(5) Thermal conductivity 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. The average value and the minimum value of 10 samples were determined.

[Example 1]
An alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm was placed in a nylon pot having an internal volume of 50 L so that the apparent filling rate was 40 vol% with respect to the internal volume. Next, 100 parts by weight of aluminum nitride powder having an average particle size of 1.5 μm (H grade manufactured by Tokuyama Corporation), 5 parts by weight of yttrium oxide, 2 parts by weight of sorbitan trioleate, 21 parts by weight of toluene, 12 parts by weight of ethanol, and butanol 2 Part by weight was added and the first stage ball mill mixing was performed for 16 hours. Thereafter, 8 parts by weight of polyvinyl butyral, 3.5 parts by weight of dibutyl phthalate, 27 parts by weight of toluene, 16 parts by weight of ethanol, and 2 parts by weight of butanol were added to this mixture, and the second stage ball mill mixing was performed for 18 hours. An aluminum nitride slurry was obtained.

  Next, the solvent was removed from the obtained aluminum nitride slurry, and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted aluminum nitride slurry was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. This aluminum nitride green sheet was punched into a predetermined size with a press machine, and a waste material of aluminum nitride green body that resulted in a punching loss was obtained.

  An alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm was placed in a nylon pot having an internal volume of 50 L so that the apparent filling rate was 40 vol% with respect to the internal volume. Next, 100 parts by weight of aluminum nitride powder having an average particle size of 1.5 μm (H grade manufactured by Tokuyama Corporation), 105 parts by weight of the waste material of the above aluminum nitride green body cut to a size of 5 cm or less, 5 parts by weight of yttrium oxide, sorbitan 2.7 parts by weight of triolate, 8 parts by weight of polyvinyl butyral, 3.5 parts by weight of dibutyl phthalate, 110 parts by weight of toluene, 65 parts by weight of ethanol, and 9 parts by weight of butanol are mixed in a ball mill for 20 hours, and regenerated nitriding. An aluminum mixture was obtained.

  The obtained regenerated aluminum nitride mixture was subjected to high-pressure dispersion once at a pressure of 200 MPa by a collision type high-pressure dispersion apparatus (HJP-25005, manufactured by Sugino Machine Co., Ltd.) to obtain a regenerated aluminum nitride slurry.

The regenerated aluminum nitride slurry was desolvated and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted aluminum nitride slurry was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had no appearance defects such as wrinkles and cracks. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

  The aluminum nitride green body thus obtained was degreased in dry air at a temperature of 580 ° C. for 4 hours to obtain a regenerated aluminum nitride degreased body having an oxygen concentration of 2.1% by weight. Thereafter, the regenerated aluminum nitride degreased body is put in a firing container and fired in a nitrogen atmosphere at 1750 ° C. (optimized densification temperature) for 5 hours, and a sintered aluminum nitride body having a width of 58 mm, a length of 58 mm, and a thickness of 0.64 mm. Got. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

[Example 2]
An alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm was placed in a nylon pot having an internal volume of 50 L so that the apparent filling rate was 40 vol% with respect to the internal volume. Next, 100 parts by weight of the aluminum nitride green body waste material cut into a size of 5 cm or less obtained in Example 1, 0.2 part by weight of sorbitan triolate, 70 parts by weight of toluene, 42 parts by weight of ethanol, and 6 parts by weight of butanol Part was added and ball mill mixing was performed for 20 hours to obtain a regenerated aluminum nitride mixture.

  The obtained regenerated aluminum nitride mixture was subjected to high-pressure dispersion once at a pressure of 200 MPa by a collision type high-pressure dispersion apparatus (HJP-25005, manufactured by Sugino Machine Co., Ltd.) to obtain a regenerated aluminum nitride slurry.

  The regenerated aluminum nitride slurry was desolvated and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted aluminum nitride slurry was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had no appearance defects such as wrinkles and cracks. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

  The aluminum nitride green body thus obtained was degreased and fired under the same conditions as in Example 1 to obtain an aluminum nitride sintered body having a width of 59 mm, a length of 59 mm, and a thickness of 0.65 mm. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

Example 3
An alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm was placed in a nylon pot having an internal volume of 50 L so that the apparent filling rate was 40 vol% with respect to the internal volume. Next, 100 parts by weight of aluminum nitride powder having an average particle diameter of 1.5 μm (H grade manufactured by Tokuyama Corporation), 67 parts by weight of waste material of aluminum nitride green body cut into a size of 5 cm or less obtained in Example 1, oxidation 5 parts by weight of yttrium, 2.7 parts by weight of sorbitan triolate, 8 parts by weight of polyvinyl butyral, 3.5 parts by weight of dibutyl phthalate, 88 parts by weight of toluene, 52 parts by weight of ethanol, and 7 parts by weight of butanol were mixed in a ball mill. This was carried out for 20 hours to obtain a regenerated aluminum nitride mixture.

  The obtained regenerated aluminum nitride mixture was subjected to high-pressure dispersion once at a pressure of 200 MPa by a collision type high-pressure dispersion apparatus (HJP-25005, manufactured by Sugino Machine Co., Ltd.) to obtain a regenerated aluminum nitride slurry.

The regenerated aluminum nitride slurry was desolvated and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted aluminum nitride slurry was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had no appearance defects such as wrinkles and cracks. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

  The aluminum nitride green body thus obtained was degreased and fired under the same conditions as in Example 1 to obtain an aluminum nitride sintered body having a width of 58 mm, a length of 58 mm, and a thickness of 0.64 mm. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

Example 4
An alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm was placed in a nylon pot having an internal volume of 50 L so that the apparent filling rate was 40 vol% with respect to the internal volume. Next, 100 parts by weight of aluminum nitride powder having an average particle diameter of 1.5 μm (H grade manufactured by Tokuyama Corporation), 67 parts by weight of waste material of aluminum nitride green body cut into a size of 5 cm or less obtained in Example 1, oxidation 5 parts by weight of yttrium, 2.7 parts by weight of sorbitan triolate, 8 parts by weight of polyvinyl butyral, 3.5 parts by weight of dibutyl phthalate, 88 parts by weight of toluene, 52 parts by weight of ethanol, and 7 parts by weight of butanol were mixed in a ball mill. This was carried out for 20 hours to obtain a regenerated aluminum nitride mixture.

  The obtained regenerated aluminum nitride mixture was subjected to high-pressure dispersion once at a pressure of 200 MPa by a collision type high-pressure dispersion apparatus (HJP-25005, manufactured by Sugino Machine Co., Ltd.) to obtain a regenerated aluminum nitride slurry.

  The regenerated aluminum nitride slurry was desolvated and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted aluminum nitride slurry was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had no appearance defects such as wrinkles and cracks. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

  The aluminum nitride green body thus obtained was degreased under the same conditions as in Example 1, and then fired in a nitrogen atmosphere at 1780 ° C. (optimized densification temperature + 30 ° C.) for 5 hours to obtain a width of 58 mm and a length of 58 mm. An aluminum nitride sintered body having a thickness of 0.64 mm was obtained. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

Example 5
Using the regenerated aluminum nitride mixture obtained in Example 3, it was subjected to high-pressure dispersion twice at a pressure of 70 MPa with a collision type high-pressure dispersion apparatus (manufactured by Sugino Machine Co., Ltd., HJP-25005) to obtain a regenerated aluminum nitride slurry. It was.

  The regenerated aluminum nitride slurry was desolvated and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted aluminum nitride slurry was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had no appearance defects such as wrinkles and cracks. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

The aluminum nitride green body thus obtained was degreased and fired under the same conditions as in Example 1 to obtain an aluminum nitride sintered body having a width of 58 mm, a length of 58 mm, and a thickness of 0.64 mm. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

Example 6
An alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm was placed in a nylon pot having an internal volume of 50 L so that the apparent filling rate was 40 vol% with respect to the internal volume. Next, 100 parts by weight of the aluminum nitride green body waste material cut into a size of 5 cm or less obtained in Example 1, 0.2 part by weight of sorbitan triolate, 70 parts by weight of toluene, 42 parts by weight of ethanol, and 6 parts by weight of butanol Part was added and ball mill mixing was performed for 20 hours to obtain a regenerated aluminum nitride mixture.

  The obtained regenerated aluminum nitride mixture was subjected to high-pressure dispersion once at a pressure of 200 MPa by a collision type high-pressure dispersion apparatus (HJP-25005, manufactured by Sugino Machine Co., Ltd.) to obtain a regenerated aluminum nitride slurry.

  Separately, an alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm was placed in a nylon pot having an internal volume of 50 L so that the apparent filling rate was 40 vol% with respect to the internal volume. Next, 100 parts by weight of aluminum nitride powder having an average particle size of 1.5 μm (H grade manufactured by Tokuyama Corporation), 5 parts by weight of yttrium oxide, 2 parts by weight of sorbitan trioleate, 21 parts by weight of toluene, 12 parts by weight of ethanol, and butanol 2 Part by weight was added and the first stage ball mill mixing was performed for 16 hours. Thereafter, 8 parts by weight of polyvinyl butyral, 3.5 parts by weight of dibutyl phthalate, 27 parts by weight of toluene, 16 parts by weight of ethanol, and 2 parts by weight of butanol were added to this mixture, and the second stage ball mill mixing was performed for 18 hours. A normal aluminum nitride slurry (A) was obtained.

  100 parts by weight of the obtained aluminum nitride slurry (A) and 100 parts by weight of the regenerated aluminum nitride slurry were mixed using a motor stirrer to obtain a mixed aluminum nitride slurry (B).

  The mixed aluminum nitride slurry (B) was desolvated to adjust the viscosity to 20000 cP. Thereafter, the viscosity-adjusted aluminum nitride slurry was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had no appearance defects such as wrinkles and cracks. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

  The aluminum nitride green body thus obtained was degreased and fired under the same conditions as in Example 1 to obtain an aluminum nitride sintered body having a width of 59 mm, a length of 59 mm, and a thickness of 0.65 mm. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

[Comparative Example 1]
The regenerated aluminum nitride mixture before the high-pressure dispersion treatment obtained in Example 1 was desolvated, and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted mixture was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had wrinkles and cracks of about 30% in terms of area ratio. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

  The aluminum nitride green body thus obtained was degreased and fired under the same conditions as in Example 1 to obtain an aluminum nitride sintered body having a width of 58 mm, a length of 58 mm, and a thickness of 0.64 mm. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

[Comparative Example 2]
The regenerated aluminum nitride mixture before the high-pressure dispersion treatment obtained in Example 3 was desolvated, and the viscosity was adjusted to 20000 cP. Thereafter, the viscosity-adjusted mixture was formed into a sheet by a doctor blade method to obtain an aluminum nitride green sheet having a width of 40 cm and a thickness of 0.75 mm. The obtained aluminum nitride green sheet had wrinkles and cracks of about 20% in terms of area ratio. This aluminum nitride green sheet was punched out by a press machine to obtain an aluminum nitride green body having a width of 68 mm, a length of 68 mm, and a thickness of 0.75 mm.

  The aluminum nitride green body thus obtained was degreased and fired under the same conditions as in Example 1 to obtain an aluminum nitride sintered body having a width of 58 mm, a length of 58 mm, and a thickness of 0.64 mm. The obtained aluminum nitride sintered body was measured for color unevenness, warpage, fracture toughness value, mechanical strength, and thermal conductivity. The results are shown in Table 1.

Claims (1)

  A mixture containing a waste material of an aluminum nitride green body and an organic solvent is subjected to high-pressure dispersion treatment at a pressure of 50 MPa or more to obtain a regenerated aluminum nitride slurry, and an aluminum nitride slurry containing at least a part of the regenerated aluminum nitride slurry is nitrided. A method for producing an aluminum green body.