JPH026305A - Production of ultrafine particle of aluminum nitride - Google Patents

Abstract

PURPOSE:To obtain AlN ultrafine particles having <=1mum particle diameters excellent moldability and sintering properties free from aggregation by heat- treating a mixture of delta alumina fine particles obtained in a gas phase and a furanphenol resin capable of containing a given ratio of water in state of precondensate in N2 and/or Nh3 atmosphere. CONSTITUTION:An Al salt such as AlCl3 or an aluminum alkoxide is thermally decomposed in a gas phase to prepare delta alumina fine particles which contains especially >=50% crystal composition of delta alumina, has <=1wt.% inorganic impurities and 0.005-0.1mum average particle diameter. On the other hand, a furanphenol resin capable of containing 20-80wt.% water in a state of precondensate is prepared. Then the delta alumina fine particles are uniformly blended with the furanphenol resin in the ratio of (65:35)-(75:25) (calculated as Al2O3:C) by a ball mill, etc., and dried. Then the dried powder is optionally granulated and then heat-treated in N2 and/or NH3 atmosphere at 1,400-1,800 deg.C to give AlN ultrafine particles almost consisting of 100% AlN single phase.

Description

[Detailed description of the invention] [Industrial use! I! P] The present invention relates to an industrial method for producing easily sinterable aluminum nitride ultrafine powder with little agglomeration.

[Conventional technology and its issues] Aluminum nitride has a higher thermal conductivity than other ceramics and has excellent heat dissipation.As +C becomes more highly integrated and operates at higher speeds, it is becoming more and more popular for packaging, metals, and substrate materials. It is being applied as a

The method for producing aluminum nitride powder is the conventionally known industrial method (+), which involves reducing and nitriding a mixture of alumina and carbon powder. (2) There is a method of nitriding metal aluminum with nitrogen or ammonia. However, in method (1), alumina and carbon are not mixed sufficiently, unreacted alumina remains, and a large amount of carbon is required, making decarburization after synthesis difficult, and
It is difficult to obtain ultrafine powder of less than m. In method (2), metal aluminum rises during the synthesis, unreacted metal aluminum remains, and synthesized aluminum nitride powder particles become coarse. Fine powder is difficult to obtain. In addition, as a method for obtaining ultrafine powder particles, Japanese Patent Application Laid-Open No. 61-171902 and G2-17190
Publication No. 3 ``Method of Synthesizing Fine Aluminum Nitride Powder'' discloses a method of nitriding metal aluminum using a wide plasma, but the manufacturing cost is high and it is difficult to obtain a large amount of powder industrially.

In view of the conventional state of the art, the present invention provides a technique to easily produce ultrafine aluminum nitride particles with an average particle diameter of 171 m or less using a method suitable for industrial production.

This is an attempt to establish a technique.

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors found that the average particle size obtained by the gas phase method was 0.005 to 0.1 μm.
Ultrafine aluminum nitride particles of 1 μm or less can be obtained by an industrially easy method by heat-treating a mixture of δ alumina and furanphenol resin, which is an initial condensate and can contain 20 wt% or more of water, in a nitrogen or ammonia atmosphere. This discovery led to the completion of the present invention. The present invention will be explained in detail below.

In the present invention, the average particle size is 1 as measured by a transmission electron microscope.
This is the area average of the diameters of the area-equivalent circles of the particles of 00IIJ.

The δ alumina used in the present invention is preferably one obtained by gas-phase thermal decomposition of aluminum salts such as aluminum chloride and aluminum sulfate, and aluminum alkoxides such as aluminum isoproxide, and particularly contains 50% or more of δ alumina as a crystal composition and is an inorganic Preferably, the impurity content is 1 wt% or less. In addition, the water content including crystal water and structured water is 10
It is preferable that it is less than wt%. Furthermore, it is necessary that the average particle diameter is 0.005 to 0.1 μm or less.

If the water content is 10 wt % or more, the trowel will not be compatible with the furanphenol resin and will likely cause uneven mixing, and will likely produce aluminum nitride fine particles exceeding 1 μm. In addition, if δ alumina with an average grain size of more than 0.1 μm is used, the progress of reductive nitriding to the inside will be slow and the heat treatment will take longer. It is difficult to obtain ultrafine particles of 1 μm or less with little agglomeration. Although it was theoretically possible to achieve the object of the present invention using δ alumina with an average particle size smaller than 0.0005 μm,
Obtaining alumina itself is difficult in practice.

The furanphenol resin that can contain 20wL% or more of water in the initial condensate state used in the present invention is
No. 171208, Japanese Patent Application Laid-open No. 60171209,
JP-A-60-171210 and JP-A-60-17
This applies to the information disclosed in Publication No. 121.1. Specifically, it can be obtained by a method shown in Examples below, but furanphenol resin, which can contain only 20 wt% or less of water in the initial condensate state, or other resins, such as phenol resin, has a 0.0% water content. It is difficult to mix homogeneously with δ alumina of 171m or less, and δ alumina aggregates and its shape remains after synthesis, making it difficult to obtain ultrafine aluminum nitride particles with less agglomeration, which is a feature of the present invention. Have difficulty.

On the other hand, it is difficult and impractical to make the furanphenol resin contain more than 80% water.

The mixing ratio of δ alumina and furanphenol resin is not particularly limited, but in order to facilitate the decarburization treatment after synthesis, δ alumina/furanphenol resin = 65:35.
~75:25 (AI, O, :C conversion) is desirable. Outside this range, decarburization after synthesis becomes difficult or unreacted alumina remains.

Predetermined δ alumina and furanphenol resin are uniformly mixed and dried in a ball mill, sand mill, etc., and in some cases, after granulation, they are pulverized for 1 hour in a nitrogen or ammonia gas atmosphere.
Heat treated at a temperature range of 400-1800°C. If the heat treatment temperature is within the above range, almost 100% aluminum nitride single phase powder can be obtained.

[Examples] The present invention will be described below based on Examples. The invention is not limited to these examples.

Examples I to 10 and Comparative Examples 1 to 5 In Examples 1 to 5, the δ alumina was commercially available Oxide-C”r manufactured by Aeronol (average particle size = O, OL μm, δ
Alumina phase = 100%), Examples 6 to 10 were obtained by vapor phase pyrolysis of aluminum isoproxide solution (
Average particle size -〇, 03~0.08μm, δ alumina phase -5
3-93%) was used. The comparative example is α shown in Table 1.
Alumina, γ alumina and δ alumina were used.

A furanphenol resin that can contain 20 wt% or more of water in the initial condensate was prepared as follows.

500 parts by weight of furfuryl alcohol and 480 parts by weight of 92% parapolmaldehyde are stirred and dissolved at 80°C, and a mixed solution of 520 parts by weight of phenol, 8.8 parts by weight of sodium hydroxide and 45 parts by weight of water is prepared while stirring. was dripped. After the dropwise addition was completed, the reaction was carried out at 80°C for 3 hours. Thereafter, a mixture of 80 parts by weight of phenol, 8.8 parts by weight of sodium hydroxide, and 1 part by weight of water was further added, and the mixture was reacted at 80° C. for 45 hours. After cooling to 30°C, it was neutralized with 70% para-toluene sulfonic acid. The neutralized product was dehydrated under reduced pressure to remove 150 parts of water and 500 parts by weight of furfuryl alcohol was added. The amount of water that this resin can contain was measured and found to be 36%. This was used in Examples I and 2. In other Examples, as shown in Table 1, samples prepared by varying the water content of rose formaldehyde were used. The resins used in Comparative Examples 1 to 4 can contain water by changing the amount of formaldehyde in the above-mentioned method (furanphenol resin prepared by I [was used (Table 1)). In Comparative Example 5, commercially available resol! ( °L
Phenol resin was used.

The results are shown in Table 1 together with the synthesis conditions.

A scanning electron micrograph t'↓ of the aluminum nitride particles of Example I is shown in FIG. As is clear from this photograph, the ultrafine particles had a uniform particle size of about 0.3/1 m, had few aggregates, and had excellent oxygen content.

[Effects of the Invention] The aluminum nitride ultrafine particles obtained by the method of the present invention have a particle size of 1 μm because alumina and resin are strictly controlled and selected.
The particle size is 6 m or less, which means less agglomeration, so it has excellent moldability and sinterability. Therefore, compared to conventional powders, it promotes sintering l:+A degree, decreases auxiliary additive addition t4, and promotes astringency and densification. In addition, since it is manufactured using the conventionally known alumina reduction nitriding method, productivity and manufacturing = 1 stroke, so tJ love (-
γ.

[Brief explanation of the drawing]

FIG. 1 is a 4-scanning electron micrograph showing the particle structure of the aluminum nitride powder obtained in Example 1.

Claims (1)

[Claims] 1. Average particle size obtained by vapor phase method is 0.005 to 0.1μ
m δ alumina and 20 to 80 wt in the initial condensate state
1. A method for producing aluminum nitride fine particles, which comprises heat-treating a mixture of furanphenol resins which may contain % of water in an atmosphere of nitrogen and/or ammonia.