JP2013087303A - Method for manufacturing metal composite superfine particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing metal composite superfine particle in which metal composite superfine particles having uniform particle size of narrow distribution width, with high yield can be manufactured in the manufacture of metal composite superfine particles.SOLUTION: The metal composite superfine particles are manufactured by disposing two-stage stirring vanes 1 made by fixing an upper stage stirring vane part 2, a cage part 4 and a lower stage stirring vane part 3 in the order to a shaft 5 in a reactor 6 in which a mixed liquid 7 of inorganic metal salt and higher alcohol are put, and by stirring and mixing the mixed liquid 7 with the two-stage stirring vanes 1 while heating the mixed liquid 7 to react the mixed liquid 7.

Description

  The present invention relates to a method for producing metal composite ultrafine particles, and more particularly to a production method for obtaining metal composite ultrafine particles having a narrow particle size distribution width in a high yield.

  With the downsizing of electronic parts such as semiconductor devices, for example, the applicability of metal composite ultrafine particles having an average particle size of 100 nm or less to electronic parts is attracting attention. Application development of the above-mentioned metal composite ultrafine particles to an electronic component such as a semiconductor device is being studied as, for example, a wiring circuit forming material or a conductive paste material.

  In general, it is known that the metal composite ultrafine particles exhibit different properties from the metal material that forms the lump as the particle size becomes smaller. In the case of metal composite ultrafine particles, This is presumably because the proportion of atoms contained in the ultrafine particles that are exposed on the surface is much larger than in the case of a metal material that forms a lump. One of the typical properties of this metal composite ultrafine particle is its low-temperature sinterability such that sintering can be started at a temperature that is significantly lower than that of powders that are usually used industrially. It is done.

  Various methods for producing such metal composite ultrafine particles have been studied. For example, an inorganic metal salt and an organic compound such as a higher alcohol are heated at a temperature of 100 to 230 ° C., depending on the organic compound used. Has proposed a method of generating metal composite ultrafine particles coated with a metal compound (see, for example, Patent Document 1). According to this method, for example, metal composite ultrafine particles in which the periphery of a metal nucleus composed of a metal (silver) component having an average particle diameter of about 7 to 10 nm is coated with an organic substance having a thickness of about 1.5 nm are manufactured. In addition, by holding the inorganic metal salt and the higher alcohol for a certain period of time in a low temperature range of 70 to 140 ° C., the inorganic metal salt is decomposed to generate a central part composed of a metal component, and the metal component of the inorganic metal salt There has been proposed a method for producing metal composite ultrafine particles in which the organic substance is coated around the center without reacting the organic substance to produce an organometallic compound (see Patent Document 2).

International Publication No. 01/70435 JP 2007-46167 A

  However, the method of the above patent document has a problem that the reaction efficiency is low in the reaction between the inorganic metal salt and the organic substance, and the unreacted inorganic metal salt remains. Therefore, it has been difficult to obtain metal composite ultrafine particles having a narrow particle size distribution width efficiently.

  The present invention has been made in view of such circumstances, and in the production of metal composite ultrafine particles, a metal capable of producing metal composite ultrafine particles with a high yield and a uniform particle size with a narrow particle size distribution width. The object is to provide a method for producing composite ultrafine particles.

  Accordingly, the present inventor has conducted various studies on techniques for increasing the reactivity when an inorganic metal salt and a higher alcohol are reacted. In the process, the inventors recalled that when a reaction between an inorganic metal salt and a higher alcohol is performed by heating, a reactor having a stirring blade having a specific structure is used. As a result, the inorganic metal salt is finely pulverized by passing through a mesh-shaped ridge provided so as to cover the outer periphery of the stirring blade having a specific structure many times by the convection generated by the stirring. The contact reaction area with the higher alcohol was increased, and it was found that the reaction of both proceeded with high activity. As a result, it has been found that unreacted inorganic metal salt does not remain, and metal composite ultrafine particles having a uniform particle size with a high yield and a narrow particle size distribution width can be obtained, thereby completing the present invention.

That is, the present invention relates to a method for producing metal composite ultrafine particles by heating and reacting an inorganic metal salt and a higher alcohol, and the reaction is performed in a reactor having a stirring blade (A) having the following structure. The gist of the present invention is a method for producing metal composite ultrafine particles, which is performed using
(A) A stirring blade provided with a plurality of stirring blades along the central axis and provided with a mesh-like ridge so as to cover the outer periphery of at least one stirring blade of the plurality of stirring blades.

  Thus, in the present invention, during the heating reaction of the inorganic metal salt and the higher alcohol, the reaction is carried out using a reactor having a specific stirring blade to produce the desired metal composite ultrafine particles. Is. For this reason, the reaction efficiency between the inorganic metal salt and the higher alcohol is improved, and as a result, metal composite ultrafine particles having a narrow particle size distribution width can be obtained with a high yield.

It is a manufacturing flowchart figure which shows the manufacturing process of the metal composite ultrafine particle of a typical example of this invention. It is explanatory drawing which shows an example of the aspect of the stirring mixing using the stirring blade in the manufacturing method of the metal composite ultrafine particle of this invention.

The description of the constituent requirements described below is an example (representative example) of the embodiment of the present invention, and is not limited to these contents.
Hereinafter, the present invention will be described in detail.
An outline of the production process of the metal composite ultrafine particles of the present invention is shown as a representative example in the production flow chart of FIG.

<Metal composite ultrafine particles>
In the present invention, ultrafine metal composite particles are produced by heating and reacting an inorganic metal salt and a higher alcohol. The ultrafine metal composite particles mainly consist of metals produced by reaction decomposition of inorganic metal salts. And metal composite ultrafine particles coated with organic residues derived from the higher alcohol.

《Inorganic metal salt》
Examples of the inorganic metal salt used as a raw material of the present invention usually include transition metals such as silver and copper, carbonates such as tin, hydrochlorides, nitrates and sulfates. Specific examples include silver carbonate, silver chloride, silver nitrate, silver sulfate, copper carbonate, copper chloride, copper nitrate, copper sulfate, tin carbonate, tin chloride, tin nitrate, and tin sulfate. In the present invention, among the above inorganic metal salts, metal carbonates are preferable because they are easily compatible with non-aqueous solvents, and silver carbonate or copper carbonate is particularly preferable.

  In addition, the said inorganic metal salt is a solid powder form normally at normal temperature.

《Higher alcohol》
In the present invention, the higher alcohol used together with the inorganic metal salt is preferably an aliphatic alcohol having 6 to 22 carbon atoms, particularly preferably 8 to 18 carbon atoms, and more preferably 10 to 16 carbon atoms. Specific examples include dodecyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, cetostearyl alcohol and the like. If the carbon number is too small, a stable coating layer tends to be hardly obtained, and if it is too large, the metal content tends to be low. These may be used alone or in combination of two or more. Among these higher alcohols, myristyl alcohol is preferably used because it is stable and has a high metal content. These higher alcohols are usually solid at room temperature. In addition, these higher alcohols may be mixed in a solid state. However, since the higher alcohol is difficult to be mixed as described above, the higher alcohol is previously melt-treated before mixing with the inorganic metal salt. It is preferred that

  The higher alcohol is used in an amount of usually 40 to 500 parts by weight, preferably 50 to 400 parts by weight, particularly preferably 60 to 300 parts by weight with respect to 100 parts by weight of the inorganic metal salt. When the proportion of the higher alcohol used is too small, the inorganic metal salt tends to remain in the reaction with the inorganic metal salt, and it tends to be difficult to produce the metal composite ultrafine particles in a high yield. . Moreover, when there is too much usage-amount of the said higher alcohol, the tendency for the removal of unreacted alcohol to become difficult will be seen.

<Reaction solvent>
In the reaction of the present invention, it is usually preferable to use an excess amount of a higher alcohol, and this is also allowed to proceed as a solvent. If necessary, the reaction is carried out in the presence of an inert solvent. Also good. For example, the solvent used in that case may be a nonpolar solvent having a boiling point close to the reaction conditions, such as 1,3,5-trimethylbenzene (mesitylene), 1,2,4-trimethylbenzene ( Pseudocumene), isopropylbenzene (cumene), diethylene glycol dibenzoate, dipropylene glycol dibenzoate and the like.

《Other additives》
In the reaction of the present invention, in addition to the inorganic metal salt and higher alcohol as raw materials, a foam inhibitor may be used for the purpose of improving the reaction yield. For example, when the inorganic metal salt is carbonate-based, carbon dioxide gas is generated, and bubbles generated thereby may be a reaction inhibiting factor. In such a case, the addition of a foam inhibitor is effective. In addition to the carbonate system, it is effective when bubbles resulting from the generated gas are produced during the reaction.

  As the foaming inhibitor, those having various foaming inhibiting actions are used, and examples thereof include ionic liquids. The ionic liquid is an ionic substance having a melting point of 150 ° C. or lower and consisting of a cation portion and an anion portion, and has an effect of suppressing gas generation in the reaction system. And in this invention, if it does not contain a metal, it will not specifically limit, Various ionic liquids are used.

  The blending amount of the ionic liquid is preferably 2.5 to 100 parts by weight, more preferably 5 to 50 parts by weight, and particularly preferably 10 to 30 parts by weight with respect to 100 parts by weight of the inorganic metal salt. .

<Mixing and heating reaction>
The method for producing metal composite ultrafine particles of the present invention is carried out by reacting the above-mentioned inorganic metal salt with a higher alcohol by heating. In the present invention, during this heating reaction, the higher alcohol and the inorganic metal salt are stirred and mixed and reacted using a reactor having a stirring blade having a specific structure, that is, a stirring blade (A) having the following structure. Thus, the reaction is carried out by bringing the higher alcohol and the powdered inorganic metal salt into contact with each other.
(A) A stirring blade provided with a plurality of stirring blades along the central axis and provided with a mesh-like ridge so as to cover the outer periphery of at least one stirring blade of the plurality of stirring blades.

  When stirring and mixing is performed using the stirring blade having the above-described configuration, the inorganic metal salt repeatedly passes through a mesh-like ridge provided so as to cover the outer periphery of the stirring blade due to the convection generated by the stirring. Therefore, the contact reaction area with the higher alcohol increases, and the reaction between the inorganic metal salt and the higher alcohol proceeds with high activity. As a result, unreacted inorganic metal salt does not remain, and metal composite ultrafine particles having a high particle diameter and a uniform particle size with a narrow particle size distribution width can be obtained.

  A plurality of the stirring blades are provided, and the number of stages is usually 2 to 5, preferably 2 stages. In addition, if the mesh-like ridges are provided so as to cover the outer periphery of the stirring blade and are provided so as to cover at least the outer periphery of the uppermost stirring blade, the above-described effects can be advantageously obtained. Therefore, it is preferable.

Examples of the shape of the stirring blade include a paddle type, a propeller type, a disper type, and a turbine type. The propeller type is preferable in terms of efficiently generating vertical convection of the liquid.
As for the shape of the mesh-shaped ridge, usually, an elliptical projection shape or a cubic projection shape provided at a position surrounding an outer space of 1.05 to 1.5 times the diameter of the stirring blade may be mentioned.
The mesh size is usually 0.5 to 10 mm, preferably 1 to 8 mm, and the porosity is usually 25 to 90%, particularly 45 to 85%.
Further, the material of the mesh-shaped ridge is preferably stainless steel similar to the stirring blade.

  Further, the position of the stirring blade is usually a position where the position of the lowermost stirring blade is 0.05 to 1 time, particularly 0.1 to 0.5 times the diameter of the stirring blade from the bottom of the reactor. On the other hand, it is preferable that the position of the uppermost blade is in a position that is 0.5 to 1.5 times, particularly 0.7 to 1 times the diameter of the stirring blade from the surface of the liquid phase part.

  Furthermore, the interval between the multistage stirring blades is preferably 0.5 to 2 times, particularly 0.7 to 1.5 times, with respect to the stirring blade diameter.

  Here, the stirring and mixing using the specific stirring blade is performed, for example, as shown in FIG. Here, a two-stage stirring blade will be described as an example. As shown in the figure, the two-stage agitating blade 1 is fixed to the shaft 5 that is connected to a motor (not shown) that is a rotational drive source, and the shaft 5 is driven by the motor to rotate the shaft 5. An upper stirring blade portion 2 that rotates as an axis and causes a downward flow in the axial direction, and is fixed to a shaft 5 below the upper stirring blade portion 2 and is driven by a motor to rotate about the shaft 5 as a rotating shaft. A lower stirring blade portion 3 that causes a flow in the same direction as the blade portion 2, and a basket-shaped mesh-shaped flange portion 4 fixed to the shaft 5 between the upper stirring blade portion 2 and the lower stirring blade portion 3. . Further, as shown in the figure, the flange portion 4 is fixed to the shaft 5 so that the opening surface faces upward, and the upper stirring blade portion 2 is housed in the opening of the flange portion 4 (upper stirring blade). In a state in which a flange is provided so as to cover the outer periphery of the portion 2.

  Then, as shown in the figure, the two-stage stirring blade 1 is installed in a reactor 6 containing a mixed solution 7 of a higher alcohol and an inorganic metal salt. The mixed solution 7 above the upper stirring blade portion 2 of the two-stage stirring blade 1 flows axially downward (in the direction of arrow A) while being stirred by the upper stirring blade portion 2 driven and rotated by a motor. And introduced into the inside of the collar part 4 through the opening surface of the collar part 4. In addition, the mixed liquid 7 flows downward in the axial direction while being stirred by the upper stirring blade portion 2 inside the collar portion 4 and is also sheared moderately at the mesh by the centrifugal force of the rotating collar portion 4. It flows out of the collar 4 (direction of arrow B). At this time, the spatter generated in the stirring and mixing process also collides with the mesh by the centrifugal force and is finely decomposed. Further, the mixed liquid 7 that has flowed out to the outside of the heel part 4 is further stirred by the rotating lower agitating blade part 3, while part of it flows upward and is stirred again by the upper agitating blade part 2. It is introduced into the part 4 (direction of arrow C). That is, the mixed liquid 7 repeats the cyclic convection consisting of stirring by the upper stirring blade portion 2 and downward flow, shearing by the centrifugal force of the flange portion 4, stirring by the lower stirring blade portion 3 and upward flow to the upper stirring blade portion 2. It will be. In particular, due to this circulation, the spatter generated in the initial stage of mixing also repeatedly collides with the mesh, and is finely decomposed in a short time.

Here, the mesh-like collar portion 4 is not limited to the one in which a wire is knitted to form a mesh. There may be.
Further, the flange 4 may be fixed not to the shaft 5 but to another support so as not to rotate in conjunction with the shaft 5.

  Moreover, from the viewpoint of performing the above-described cyclic convection well and stirring and mixing well, the rotation speed of the stirring blade (two-stage stirring blade 1) during stirring is usually 200 to 1200 rpm, and more preferably 300 to 800 rpm is preferred.

  Further, from the viewpoint of good circulation convection as described above and good stirring and mixing, the ratio (Φ1 / Φ2) between the diameter (Φ1) of the lower stirring blade 3 and the inner diameter (Φ2) of the reactor 6 Is preferably 0.2 to 0.7, more preferably 0.25 to 0.5.

  In this manner, the higher alcohol and the inorganic metal salt are stirred and mixed while the heating reaction of both proceeds. The heating is usually performed by heating the reactor 6. For example, the reactor 6 is a reactor having a temperature control function, and is particularly preferably a heating device (a heating jacket or the like), and more preferably a reflux condenser. Moreover, as a material of the reactor 6, the thing of glass lining and the thing of resin lining are used suitably.

The reaction in the present invention may be performed under normal pressure or under pressure, but is usually performed under normal pressure.
And about the heating reaction in this invention, reaction is normally performed on the heating conditions for about 20 to 300 minutes at 40-200 degreeC. Further, the above reaction is preferably performed in two or more stages, particularly preferably in two stages. As the above two-stage reaction conditions, first, a heating reaction is performed at 40 to 70 ° C., particularly 50 to 65 ° C., for 20 to 120 minutes, particularly 25 to 90 minutes, particularly 30 to 60 minutes, and then It is preferable to carry out a heating reaction at 130 to 200 ° C., particularly 140 to 180 ° C., particularly 150 to 170 ° C., for 20 to 300 minutes, particularly 30 to 240 minutes, particularly 30 to 180 minutes.

  In the present invention, as described above, the reaction is preferably performed in two stages. In the former stage reaction, the inorganic metal salt is dispersed in the higher alcohol, the inorganic metal salt is refined, and the latter stage reaction is performed. The reaction between the finely divided fine particles of the inorganic metal salt and the higher alcohol proceeds with high activity. During this reaction, the color tone of the inorganic metal salt changes with the progress of the previous reaction (in the case of silver, changes to brown), and changes with the progress of the subsequent reaction (in the case of silver, changes to blue-purple).

  In the reaction of the present invention, water, carbonic acid and the like are by-produced by the progress of the reaction. Therefore, it is preferable to proceed the reaction while distilling off these volatiles in the subsequent reaction.

  By the above reaction, a reaction mixture containing metal composite ultrafine particles coated around the metal with organic residues derived from higher alcohol is obtained.

"cooling"
The reaction of the present invention can be stopped by cooling the reaction mixture to usually 80 ° C. or lower, preferably 60 ° C. or lower. And after the said reaction stops, for example, by mix | blending a C1-C3 alcohol with a reaction mixture, the metal composite ultrafine particle in a reaction mixture will aggregate easily, and a metal composite ultrafine particle will precipitate easily. . As said C1-C3 aliphatic alcohol, ethanol etc. are suitable, for example.

"Washing"
By the above reaction, a reaction mixture containing metal composite ultrafine particles centered on the metal and coated with organic residues derived from a higher alcohol is obtained. After separating the metal composite ultrafine particles from the reaction mixture, this metal is separated. It is preferable to wash the composite ultrafine particles with a lower alcohol. The lower alcohol is usually an aliphatic alcohol having 1 to 3 carbon atoms, and ethanol is particularly preferable.

As a washing method, a suspension washing method such as decantation is generally used, but other methods include sprinkling washing and distribution washing.
Sprinkling washing includes a method of sprinkling the washing liquid on the fixed cake and a method of sprinkling the washing liquid while centrifuging. There is a method of adding more cleaning liquid.
The suspension washing method is carried out, for example, by adding a lower alcohol to the reaction mixture, stirring and mixing, allowing to stand, and then repeating the solid-liquid separation operation for separating the precipitated metal composite ultrafine particles. In this case, the lower alcohol may be added to the reaction mixture at any time as long as the temperature of the mixture becomes 50 ° C. or lower, preferably 40 ° C. or lower.

  The washing temperature is usually 20 to 40 ° C., and the amount of lower alcohol used is usually 1 to 50 times the weight of the metal composite ultrafine particles. The number of washings is repeated until the desired purity of the metal composite ultrafine particles is obtained, but is usually 2 to 10 times.

《Solid-liquid separation》
After the washing, the metal composite ultrafine particles and the washing waste liquid are usually separated by solid-liquid separation, and the washing waste liquid is removed. As said solid-liquid separation method, it can carry out by methods, such as filtration and centrifugation.

《Dry》
The metal composite ultrafine particles after washing are usually subjected to a drying treatment. The drying temperature is usually about 20 to 80 ° C. Moreover, even if the solid after drying is agglomerated, it can be easily powdered by grinding or the like.

<Metal composite ultrafine particles>
The obtained metal composite ultrafine particles are ultrafine particles (nanoparticles) composed mainly of a metal produced by reaction decomposition of the inorganic metal salt and covered with the organic residue derived from the higher alcohol. is there.

  The average particle diameter of the metal composite ultrafine particles obtained by the production method of the present invention is preferably 1 to 100 nm, particularly preferably 2 to 50 nm, and further preferably 3 to 30 nm. The average particle diameter of the metal composite ultrafine particles is measured, for example, as follows. That is, an arbitrary measurement sample is taken out from the population of the metal composite ultrafine particles to be measured, and the particle diameter per fixed area is measured with reference to a scale bar using a commercially available transmission electron microscope (TEM). can do.

  Moreover, the metal composite ultrafine particles obtained above can be identified by performing, for example, thermogravimetric analysis (TG) measurement and infrared absorption analysis (IR) measurement.

  The metal composite ultrafine particles produced by the present invention have a narrow particle size distribution width, and therefore, the firing temperature when firing using this is low, and a uniform and good metal surface can be obtained.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

[Example 1]
In an approximately 1 liter reactor (glass reactor: inner diameter 130 mm × height 140 mm) (see FIG. 2) equipped with a heating device, a reflux condenser, and a two-stage stirring blade under the conditions shown below, 200 g of heated and melted myristyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) was supplied, and then 100 g of powdered silver carbonate (dark blue) (manufactured by Nisshin Chemical Co., Ltd.) was added.

<Two-stage blade agitator>
Made by Chuo Rika Co., Ltd., simplified NCR100-CB5-D
Lower stirring blade diameter: 50 mm
Diameter of upper stirring blade: 50mm
Size of mesh-like ridge provided around the upper stirring blade part: diameter 53 mm x depth 40 mm
Distance between lower stirring blade and upper stirring blade: 35 mm
Ratio (Φ1 / Φ2) between the diameter (Φ1) of the lower stirring blade and the inner diameter (Φ2) of the reactor: 0.4
Mesh porosity: 69%

The above contents are reacted at 60 ° C. for 40 minutes with stirring at 500 rpm, then the contents are heated, heated to 160 ° C. over 15 minutes, and kept at the same temperature for 2 hours to continue the reaction. did. In addition, with the progress of the above reaction, the reaction was in a reflux state in the later stage.
In the preceding reaction, the color of the mixture changed to brown, and in the latter reaction, it changed to blue-violet.

  Thereafter, the internal temperature was cooled to 80 ° C. or lower, and 50 ml of ethanol was gradually added thereto (stirring condition: 500 rpm). Further cooling was continued to bring the internal temperature to 40 ° C. or lower, and the solution was transferred to a 3 liter beaker. . The 1 liter reactor was also washed with ethanol and the wash was added to a 3 liter beaker.

  In the washing treatment, 1 liter of ethanol was added to the separated metal composite ultrafine particles, stirred with a glass rod, and allowed to stand at 25 ° C. After standing for about 6 hours, the reaction mixture was separated into a yellow transparent supernatant and a dark gray sediment. Next, after draining as much of the supernatant as possible by decantation, 1 liter of ethanol was newly added to the beaker, and after stirring well with a glass rod, it was allowed to stand. After standing for about 3 hours, it was separated into an almost colorless and transparent supernatant and a slightly grayish, dark gray sediment. Next, the supernatant liquid was discharged as much as possible by decantation.

  Subsequently, the dark gray sedimentation part (solid content) which is the residue which remove | eliminated the said supernatant liquid was moved to the prepared Kiriyama funnel using fresh ethanol, and suction filtration was performed. In addition, when the filtration progressed sufficiently by suction filtration using the Kiriyama funnel, a solid (blue cake) remaining on the funnel was cracked.

  The cracked solid (blue cake) was shrunk and dried with a spatula until it cracked (about 24 hours), and further dried until it could be crushed with a glass rod (about 48 hours), the obtained cake was pulverized into powder.

<Identification>
With respect to the metal composite ultrafine particle powder obtained by drying and pulverizing, thermogravimetric analysis (TG) measurement and infrared absorption analysis (IR) measurement were performed using the following apparatus. As a result of these measurements, the obtained metal composite ultrafine particles had an organic residue (mainly C ₁₄ H ₂₉ COO- and C ₁₄ H) derived from the myristyl alcohol around the silver produced by the reaction decomposition of the silver carbonate. It was confirmed to be a metal composite ultrafine particle coated with ₁₃ H ₂₇ COO-). A peak derived from unreacted silver carbonate was not detected. Furthermore, the average particle diameter of the obtained metal composite ultrafine particles was measured using a transmission electron microscope (TEM). As a result, it was confirmed that ultrafine particles having a narrow particle size distribution width of 4 to 8 nm were obtained. It was.

<< Thermogravimetric analysis (TG) measurement >>
Measuring device: “Thermal Analysis TG-7” manufactured by Perkin Elmer
<< Infrared absorption analysis (IR) measurement >>
Measuring instrument: “Avatar 360” manufactured by Nicolet
<Measurement of average particle size>
Measuring equipment: “Transmission electron microscope H-7100FA type” manufactured by Hitachi, Ltd.

[Example 2]
First, solid lauryl alcohol (manufactured by Kishida Chemical Co., Ltd.) (melting point: 24 ° C.) was prepared at room temperature, and this was placed in a dryer at 50 ° C. and heated for 5 hours to melt. Next, 100 g of the molten lauryl alcohol is supplied to a 1 liter reactor (glass reactor) equipped with a heating device, a reflux condenser and a two-stage stirring blade similar to that in Example 1, and the powdery state is supplied to this. 60 g of silver carbonate (dark blue) (manufactured by Nisshin Chemical Co., Ltd.) was added.

The above contents are reacted at 50 ° C. for 1 hour with stirring at 500 rpm, then the contents are heated, heated to 140 ° C. over 15 minutes, and kept at the same temperature for 3 hours to continue the reaction. did. In addition, with the progress of the above reaction, the reaction was in a reflux state in the later stage.
Thereafter, the same operation as in Example 1 was performed to obtain a metal composite ultrafine particle powder.

The obtained metal composite ultrafine particle powder was subjected to thermogravimetric analysis (TG) measurement and infrared absorption analysis (IR) measurement in the same manner as in Example 1. As a result, the silver produced by reaction decomposition of the silver carbonate was obtained. It was confirmed that the metal composite ultrafine particles were coated around the center with the organic residues derived from the lauryl alcohol (mainly C ₁₂ H ₂₅ COO— and C ₁₁ H ₂₃ COO—). A peak derived from unreacted silver carbonate was not detected. Furthermore, the average particle diameter of the obtained metal composite ultrafine particles was measured using a transmission electron microscope (TEM). As a result, it was confirmed that ultrafine particles having a narrow particle size distribution width of 4 to 8 nm were obtained. It was.

[Reference Example 1]
In Example 1, during the heating reaction of myristyl alcohol and silver carbonate, stirring was carried out using a two-stage stirring blade having no soot (same as the stirrer used in Example 1 except for no soot). . Other than that was carried out similarly to Example 1, and manufactured the solid substance which is a sample. About the obtained sample, it identified similarly to Example 1 and measured the average particle diameter.

In the TEM observation of the obtained sample (solid material), it was confirmed to be 8 to 15 nm (major axis) and a small particle size distribution, and in TGA measurement, a large weight loss at 160 to 180 ° C. was observed. not, and in the IR measurement, Ag ₂ CO ₃ derived from 1375 cm ^-1, a peak of 1445cm ^-1 were observed. From this, it can be seen that in the production process of the metal composite ultrafine particles, the use of a special two-stage stirring blade with a ridge is a better method because the particle size distribution becomes smaller.

  The production method of the present invention is a method capable of efficiently producing uniform ultrafine particles with a narrow particle size distribution width in a high yield, and the metal composite ultrafine particles obtained thereby have a firing temperature when firing. Can be lowered. For example, it is useful as a forming material for fine wiring of an electronic component such as a semiconductor device or a conductive material used when electrically connecting electrodes of an electronic component such as a semiconductor device.

1: Two-stage stirring blade 2: Upper stirring blade portion 3: Lower stirring blade portion 4: Saddle portion 5: Shaft 6: Reactor 7: Mixture

Claims (7)

In the method for producing metal composite ultrafine particles by heating and reacting an inorganic metal salt and a higher alcohol, the reaction is performed using a reactor having a stirring blade (A) having the following structure. A method for producing metal composite ultrafine particles.
(A) A stirring blade provided with a plurality of stirring blades along the central axis and provided with a mesh-like ridge so as to cover the outer periphery of at least one stirring blade of the plurality of stirring blades.   The method for producing metal composite ultrafine particles according to claim 1, wherein the stirring blade is a two-stage stirring blade, and a mesh-like ridge is provided so as to cover the outer periphery of the upper stirring blade.   The method for producing metal composite ultrafine particles according to claim 1 or 2, wherein the rotation speed of the stirring blade during the reaction is 200 to 1200 rpm.   The method for producing metal composite ultrafine particles according to any one of claims 1 to 3, wherein the inorganic metal salt is a metal carbonate.   The method for producing metal composite ultrafine particles according to any one of claims 1 to 4, wherein the higher alcohol is an alcohol having 6 to 22 carbon atoms.   The method for producing metal composite ultrafine particles according to any one of claims 1 to 5, wherein the higher alcohol is used in an amount of 40 to 500 parts by weight per 100 parts by weight of the inorganic metal salt.   The produced metal composite ultrafine particles are those in which the metal is the center and the periphery is coated with an organic residue derived from a higher alcohol, and the average particle size is 1 to 100 nm. A method for producing a metal composite ultrafine particle according to claim 1.

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