JPH02296708A - Method for surface coating of aln powder - Google Patents

Abstract

PURPOSE:To obtain a coating layer having excellent water resistance, heat resistance and mechanical strength by dispersing AlN powder coated with dibasic acid in a solution such as diamine and then forming a polyamide resin coating film on the surface of the particle. CONSTITUTION:AlN powder and solution of dibasic acid or its derv. with a coupling agent added (e.g. 1,8-octane dicarbonylchloride, 1,4-butane diarboxylic acid, chlorides of these) are mixed and then the solvent is volatilized to coat the surface of the AlN powder particle. Then the coated AlN powder is dispersed in a solution of diamine or its derv. to effect polymerization on the particle surface to form the polyamide resin coating film.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for coating the surface of aluminum nitride (AxN) powder, and in particular, coats AuN powder with a high-performance coating to improve stability against moisture and oxygen. The present invention relates to a surface coating method of AuN powder for easily and efficiently forming the surface of AuN powder.

[Prior art and prior art] Al1N powder is thermodynamically extremely unstable in the atmosphere, and in particular, its fine powder easily reacts with oxygen and moisture. For example, when Al1N powder is kept at 30°C and 80% relative humidity for about 40 days, Ba
yerite.

Aluminum hydroxide CAj2 (
OH) It changes to 3).

A It N + 3 H20→AJ2 (OH)3
+NH3 Therefore, when storing AuN powder, it is necessary to completely seal it in a container after drying or store it in an N2 or NH3 gas atmosphere, which makes management difficult. Even if decomposition into Al2(OH)3 etc. can be substantially prevented during storage, it is inevitable that decomposed impurities will be generated in the various steps before firing during the production of the sintered body. That is, when a slurry of AJZN powder is prepared using water as a medium, AlN
Since some of the Al2(OH)a generated in the slurry is mixed into the
(OH) 3 changes to α-alumina (Al2203), and Al2203 in the obtained sintered body increases. Therefore, the properties of the sintered body such as thermal conductivity are significantly impaired. For this reason, in the past, it was not possible to form an aqueous slurry, and molding was performed using an organic solvent and a molding binder, resulting in high processing costs.

Therefore, in order to stabilize AJ:LN powder, it has been proposed to form an N film on the powder surface, and recently, Au
After forming a hydrophobic film on the N powder surface, a hydrophilic film is formed, specifically, Al1 as the first surface treatment.
After covering the surface of the N powder with an inorganic or organic surface treatment agent to suppress its reactivity with water, as a second surface treatment, this first treated powder is coated at an interface using water as a medium. AuN powder treated in an activator to improve its dispersibility in water has been proposed (Japanese Patent Laid-Open No. 62-207770).

However, the AJZN powder disclosed in JP-A No. 62-207770 has (1) poor heat resistance of the coating (cannot withstand 200°C);

■ Mechanical strength, chemical resistance, and durability of the film are insufficient.

(2) According to (2), when milling using a mill or spray dryer, the coating is damaged and hydration of AJ2N is likely to occur.

There were drawbacks such as.

By solving the above conventional problems, we have formed a water-resistant protective coating on AuN powder that has excellent heat resistance, high mechanical strength, and extremely durability, making it possible to process and mold AjZN powder in aqueous systems. As a surface-coated Aj2N powder and a method for producing the same, by which a high-performance AffiN sintered body can be manufactured at low cost, the present applicant has proposed an Aj2N powder whose particle surface is coated with a polyamide resin, and , like this
In producing 1N powder, a method is used in which a polyamide resin coating is generated on the particle surface of AuN powder that has been hydrophobically treated with a coupling agent or the like by a polycondensation reaction between a dibasic acid or its derivative and diamines or diamine derivatives. Heading: First patent application filed (Japanese Patent Application No. 63-221871, hereinafter referred to as "Prior Application J").

[Problems to be Solved by the Invention] According to the method of the earlier application, it is possible to easily and efficiently produce A, u N powder on which a high-performance polyamide resin coating is formed. The surface-coated Al1N powder produced by the proposed method has a polyamide resin coating formed on the surface of the AIN powder particle via a hydrophobic treatment agent layer such as a coupling agent layer, and may vary depending on the manufacturing conditions. However, as shown in Figure 2, rather than the AuN powder in which the polyamide resin coating is directly formed on the coupling agent layer, the coupling agent layer 3 formed on the surface of the IQN powder particles 2 is , AfiN powder IB is obtained in which a polyamide resin coating 4 is formed, including the liquid phase 5 of the organic solvent and the 31 residues during coating formation.

That is, the method of the previous application is a so-called liquid-liquid polymerization in which, for example, a dibasic acid or its derivative and a diamine or a diamine derivative are reacted in a liquid phase on the surface of the AuN powder, so that the formed polyamide Residual monomers and liquid phase 5 of organic solvent are likely to be included in resin coating 4 .

Therefore, the surface-coated AuN powder obtained by the method of the prior application has the following problems.

■ Press pressure during molding causes the coating to tear and the internal liquid phase leaks out.

For this reason, press shrinkage and firing shrinkage are large, formability and sinterability are impaired, and product defects are likely to occur. Additionally, the mold is contaminated by the leachable liquid phase, requiring cleaning of the mold, which reduces productivity.

■ Since the formed film itself is relatively thick and contains a liquid phase, the ratio of organic matter in the film and liquid phase to the surface-coated AuN powder is extremely high, for example, about 20%. Become. For this reason, the amount of chemicals used is large and the cost of raw materials increases, and the original characteristics of the Aj2N powder may be impaired due to the thick coating and liquid phase coating layer.

The present invention solves the problems of the prior application mentioned above, and makes it possible to easily and efficiently form a relatively thin polyamide coating with high productivity without including a liquid phase on the surface of AfLN powder. The object is to provide a method for covering the surface of the body.

[Means for Solving the Problems] The AlN powder surface coating method of the present invention coats the surface of AfLN powder particles with a dibasic acid or a derivative thereof, and coats the coated Aj2N powder with a diamine or a diamine. It is characterized in that a polyamide resin film is produced by dispersing it in a solution of the derivative and causing a polymerization reaction on the surface of the AuN powder particles.

The present invention will be explained in detail below.

In the method of the present invention, first, the surface of AJ2N powder particles is coated with a dibasic acid or a derivative thereof. Specifically, AfLN powder and a solution of a dibasic acid or its derivative added with a coupling agent are added and mixed, and the resulting mixed slurry is evaporated and removed by a method such as rapid heat drying. .

In the present invention, the coupling agent specifically includes:
KBM1003 (manufactured by Shin-Etsu Chemical, vinyltrimethoxysilane), KR44 (manufactured by Ajinomoto, isopropyl tri(N-aminoethyl-aminoethyl) titanate),
AL-M (manufactured by Ajinomoto Co., Ltd., acetalkoxyaluminum diisopropylate), etc. can be used.

In addition, examples of dibasic acids or derivatives thereof include 1°8-octanedicarboxylic acid, 1,4-butanedicarboxylic acid, 1,7-hebutanedicarboxylic acid, 1,5-pentanedicarboxylic acid, and 1,6-hexane. Dicarboxylic acids and their chlorides, etc. can be used.

Examples of the solvent for dissolving such a dibasic acid or its derivative include one or more organic solvents such as cyclohexane, ethyl alcohol, acetone, hexane, methyl alcohol, and chloroform.

The amount of the coupling agent used is preferably about 1.0 to 4.0 mj2 per 100 g of AJ:LN powder.

In addition, the concentration of the dibasic acid or its derivative solution and the ratio of AlN powder added and mixed with the solution vary depending on the coating amount of the surface-coated A42N powder to be manufactured, but usually 0.1 ~0.3m Ofl/40 for 100rrIL of solution of dibasic acid or its derivative of about 11
Preferably, ~60 g of Aj2N powder is mixed.

In addition, in the present invention, coating treatment with a dibasic acid or its derivative is also examined without using a coupling agent. However, since the surface of AJ2N powder is wood-philic, it has poor wettability with solutions of dibasic acids or their conductors during coating treatment, and the dispersibility of A42N powder is poor, resulting in poor coating film formation. It tends to be uniform. Therefore, it is preferable to use a coupling agent in the present invention.

The AJ2N powder coated in this way is then dispersed in a solution of diamine or diamine derivative, and
By causing a polymerization reaction on the particle surface of βN powder, a polyamide resin coating is generated.

Specifically, the coated AuN powder is dispersed in water to which a surfactant has been added to form a slurry, and a solution of diamine or diamine derivative is added to this slurry and mixed and stirred.

Examples of the surfactant include nonionic surfactants with a high HLB value, such as polyoxyethylene alkyl ether,
Polyoxyethylene alkyl allyl ether, polyoxyethylene derivatives, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, etc. can be used.

In addition, as diamine or diamine derivative, 1.6-
Diamithexane, 1.7-diaminohebutane, 1.8
-diaminooctane, 1.9-diaminononane, 1.1
0-diaminodecane, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine and derivatives thereof, etc. can be used.

Water is an example of a solvent for dissolving such diamines or diamine derivatives.

The amount of surfactant used is preferably about 5 to 10 ml per 100 g of AJ2N powder. In addition, the concentration of the diamine or diamine derivative solution and the proportion of the AuN powder to be added and mixed with the solution should be set to a level sufficient to cause a polymerization reaction with the dibasic acid or its derivative attached to the surface of the AuN powder particles. The amount may be as long as the amount of diamine or diamine derivative is added, and although it varies depending on the amount of coating of the surface-coated AlN powder to be produced, it is usually 0.02 to 0.
It is preferable to mix 50 to 100 g of coated Aj2N powder to 100 mf of a diamine or diamine derivative solution at a temperature of about 0.05 mo C/1.

In this way, by dispersing the AjZN powder coated with the coupling agent and the dibasic acid or its derivative in a solution of the diamine or diamine derivative, the dibasic acid or its derivative and the diamine are coated on the particle surface of the AfN powder. Alternatively, a diamine derivative undergoes a polycondensation reaction to produce a polyamide resin coating.

After the reaction is completed, the solvent such as water is evaporated by drying the slurry under rapid heat to obtain a surface-coated AfN powder having a polyamide resin coating formed thereon.

As shown in FIG.
This is an AlN powder IA in which a polyamide resin coating 4 is formed with good adhesion on the surface of AJZN powder particles 2 to which A is attached, with almost no liquid phase included.

In addition, the method of the present invention uses A used as a molding and firing material.
When producing J2N powder, a predetermined amount of Y2O3 is added in advance.
Needless to say, the present invention can be applied to ACN powder mixed with a sintering aid such as powder.

[Operation] According to the method of the present invention, unlike the liquid-liquid polymerization of the previous application,
By forming a polyamide resin film through so-called solid-liquid polymerization, in which the dibasic acid or its derivative on the surface of the AJ2N powder particles reacts with the diamine or diamine derivative in the solution, there are no unreacted particles or particles within the film. This makes it possible to obtain a surface-coated AiN powder that does not contain a liquid phase such as a solvent.

For this reason, the amount of organic matter in the coating is significantly reduced to about 5% compared to the surface-coated AJZN powder, and a coating with excellent water resistance, heat resistance, and extremely high mechanical strength can be created without impairing the original properties of the AuN powder. Good adhesion, thin and uniform film thickness,
Furthermore, it is possible to form the coating so that almost every single particle is coated.

Further, the amount of the coating formed on the surface of the AlN powder particles can be easily adjusted by adjusting the amount of the dibasic acid or its derivative attached, the amount of diamine or diamine derivative used, etc.

[Examples] The present invention will be described in more detail with reference to Examples and Comparative Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

In addition, in the following examples and comparative examples, the reagents used are as follows.

1.8-Octane dicarbonyl chloride: Sebacoyl chloride (manufactured by Wako Pure Condiments) CILCO (CH2)a C0CfL=239.101
．． 6-diamithexane (hexamethylene diamine) (
(manufactured by Wako Pure Condiments) NHR (CH2) 6 NHR depth 116.21 ■ Chloroform (manufactured by Wako Pure Condiments) CHCJls = 119 ■ Cyclohexane (manufactured by Wako Pure Condiments) C6HL2 = 84.2 ■ Surfactant Emulgen A-60 (■ (Manufactured by Kao) (Polyoxyethylene derivative HLB = 12.8) ■ Coupling agent KBM1003 (Manufactured by Shin-Etsu Chemical ■) CH2CHS
i (OCHs)3 = 148.2 Also, the raw material A
The following (2) was used as the J2N powder, and the following (2) was used as the sintering aid.

■ High purity aluminum nitride, F (manufactured by Tokuyama Soda ■) ■ Y2O3 (manufactured by Shin-Etsu Chemical ■) Example 1 25 g of sebacoyl chloride was dissolved in 500 mj2 of cyclohexane to prepare solution A (0.2 m o A/J2). Separately, 2.32 g of hexamethylene diamine was dissolved in 500 mA of distilled water, and solution B (0.04 mon/I
l) was prepared.

14.25 g of AβN powder and 0.0 g of sintering aid Y2O3 powder.
At the same time, 75 g of the mixture was mixed in a ball mill, and at the same time, 22 ml of solution A, 10 mJZ of cyclohexane, and 150 μl of a coupling agent were added in order to fix sebacoyl chloride, and the mixture was mixed for 24 hours.

The obtained slurry was rapidly dried on a hot plate at 120° C. to volatilize cyclohexane to obtain AjZN powder coated with sebacoyl chloride. Then, the obtained A
100 m of distilled water containing AN powder and 1 m of surfactant
A slurry C was obtained by dispersing the slurry in A.

Next, in order to polymerize sebacoyl chloride and hexamethine diamine on the surface of the Aj2N powder, 10 to 20 mA of solution B was added to Sura+ and +-C, and the mixture was stirred for several minutes.

Since a polyamide resin film was formed on the surface of the IQN powder particles by the reaction, the reaction solution was rapidly dried on a hot plate at 200° C. in order to separate the obtained surface-coated AfN powder from water.

The physical properties and characteristics of the obtained surface-coated AlN powder were investigated by the following method, and the results are shown in Table 1.

Using 1 g of Aj2N powder coated with Iλ
After baking for 1 hour, the organic content was measured from the weight loss on baking.

Formability, general physical properties The surface-coated AiN powder was press-molded at 1000 kgf/crn' using molds of 12 mmφ and 30 mmφ, and fired at 1880°C for 2 hours in a nitrogen atmosphere. I got a body. The quality of moldability at this time is ◎, O1△,
Evaluation was made on a four-grade scale of x, and various physical properties of the obtained fired body were measured.

Thermal conductivity The fired body obtained above was measured using a laser flash thermal constant measuring device (TC-7000) J manufactured by Shinku Riko Co., Ltd.

The fired body obtained above was measured at IMHz using an "R4192A Impedance Analyzer" manufactured by YHP (Yokogawa Hewlett-Baccardo).

Comparative Example I Aj2N powder 14.25g, sintering aid Y2O3 powder 0.
75g and binder (rG7211 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
J) 0.60 g was mixed for 24 hours using 30 ml of cyclohexane as a solvent.

This was spread on a hot plate and subjected to rapid heat drying treatment at 200°C to obtain a mixed powder.

The physical properties and characteristics of the obtained powder were investigated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 (method of the previous application) 25 g of sebacoyl chloride was dissolved in 500 ml of a mixed solvent of cyclohexane/chloroform = 3:1 (volume ratio).
A solution (2) of 0.2 mof/JZ was prepared. Separately, 2.32 g of hexamethylene diamine was dissolved in 500 mJZ of distilled water to make a 0.04 m o 11 / fl solution! (2) was prepared.

AJ2N powder 14.25g and sintering aid Y2O3 powder 0
．． About 150 μl of a coupling agent was added to 75 g of the product, and the mixture was mixed in 30 ml of acetone for 24 hours for hydrophobic treatment. After mixing, the resulting slurry was heated on a hot plate for 12 minutes.
Rapid heat drying was performed at 0°C, and the resulting dry powder was added to solution 11.
Next, the dispersion liquid was emulsified in 30 mA of distilled water containing 1 ml of surfactant, and the emulsion was converted into a solution! 10 to 20 ml of (2) was added to cause polymerization. Then, a mixed solvent (cyclohexane:chloroform-
3:1 volume ratio) to stop the reaction and drying on a hot plate at about 200°C to form a surface-coated AfN.
A powder was obtained.

The physical properties and characteristics of the obtained powder were investigated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 (method of JP-A No. 62-207770) Powder obtained by hydrophobic treatment in the same manner as Comparative Example 2 was
-207770, 1.5g of sodium oleate was dissolved in 30ml of distilled water according to the method.
Mix for about 2 minutes, then use a hot plate for 2 minutes.
Drying treatment was carried out at 00°C.

The physical properties and characteristics of the obtained powder were investigated in the same manner as in Example 1, and the results are shown in Table 1.

Note that when the powder obtained in this example was press-molded and fired, many cracks appeared and the powder collapsed, so the characteristics of the fired product could not be measured.

Table 1 The following is clear from Table 1.

The powder obtained in Comparative Example 3 had poor mold releasability, contained a large amount of organic content, and was highly deformed upon firing. For this reason, unless a degreasing treatment is performed by holding the material at a temperature of 200 to 500° C. for a long time, it is not possible to obtain a good baked product by molding and baking.

In the powder obtained in Comparative Example 1, the density of the molded body is low, and therefore the strength of the fired body is low.

The powder obtained in Comparative Example 2 has a high organic content because it contains a liquid phase consisting of unreacted monomers and solvent.

Therefore, the amount of chemicals used is large, and there is also the problem of reduced productivity due to outflow of the liquid phase during molding.

In contrast, the surface coating A obtained by the method of the invention
According to uN powder, it has good moldability, low porosity,
High-strength molded bodies and fired bodies can be obtained with high productivity. Moreover, since there is no problem of inclusion of the liquid phase, the amount of chemicals used is about % compared to the method of Comparative Example 2, and the cost of raw materials is also reduced.

[Effects of the Invention] As detailed above, according to the method for surface coating ALN powder of the present invention, it has excellent water resistance, heat resistance, and mechanical strength;
A high-performance polyamide resin coating layer that can sufficiently protect the AJ2N powder particles can be easily, inexpensively, and efficiently formed on the surface of the AJ1N powder particles.

According to the surface wave NAj2N powder produced according to the present invention, the protective film is not destroyed in processing steps such as aqueous treatment, heat treatment, and milling treatment, so that the AJZN powder is It is possible to obtain an AIN powder that is prevented from changing to OH)3, does not generate A120s, has high thermal conductivity, and has excellent various properties. Moreover, since the polyamide resin film does not contain unreacted particles or the liquid phase of the solvent, there is no problem of press shrinkage or firing shrinkage due to leaching of the liquid phase during molding and firing. Sexuality is also greatly improved.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of surface-coated AuN powder obtained by the surface coating method of AJ2N powder of the present invention, and FIG. 2 is a surface-coated Af mainly obtained by the method of the earlier application.
FIG. 2 is a schematic cross-sectional view showing LN powder. IA, IB...Surface coating AJ2N powder, 2...Af
LN powder particles, 3... Coupling agent layer, 4... Polyamide resin coating. Patent applicant Inax Co., Ltd.

Claims (1)

[Claims] (1) The surface of AlN powder particles is coated with a dibasic acid or its derivative, the coated AlN powder is dispersed in a solution of diamine or diamine derivative, and a polymerization reaction is carried out on the particle surface of the AlN powder. A method for coating the surface of AlN powder, characterized by forming a polyamide resin film.