US20140119978A1

US20140119978A1 - Metal nano particle and method for surface treating the same

Info

Publication number: US20140119978A1
Application number: US14/065,120
Authority: US
Inventors: Jung Wook Seo; Tae Ho Kim; Young Ku Lyu; Kwang Myung Kim; Kwan Lee; Dong Hoon Kim
Original assignee: Samsung Electro Mechanics Co Ltd
Current assignee: Samsung Electro Mechanics Co Ltd
Priority date: 2012-10-29
Filing date: 2013-10-28
Publication date: 2014-05-01
Also published as: KR101472634B1; KR20140054634A; CN103785823A

Abstract

Disclosed herein is a method for surface treating metal nano particles, including: surface treating metal nano particles with an alkanol amine containing solution.

Description

CROSS REFERENCE(S) TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. Section 119 of Korean Patent Application Serial No. 10-2012-0120361 entitled “Metal Nano Particle and Method for Surface Treating the Same” filed on Oct. 29, 2012, which is hereby incorporated by reference in its entirety into this application.

BACKGROUND OF THE INVENTION

1. Technical Field
The present invention relates to metal nano particles and a method for surface treating the same, and more particularly, to a method for surface treating metal nano particles capable of effectively removing impurities that remain in metal nano particles having high purity and metal nano particles synthesized therefor.
2. Description of the Related Art
Generally, a multi-layered chip element such as a multi-layer ceramic capacitor (MLCC) is manufactured by forming internal electrodes on a plurality of dielectric sheets, laminating the sheets to manufacture a laminate, and forming external electrodes on the laminate. As a material for the internal electrode, a metal paste including various types of metal nano particles is used. As an example, there is a technology of forming internal electrodes of a multi-layer ceramic capacitor by using a nickel paste including nickel nano particles.
The metal nano particles are synthesized by methods, such as a liquid phase method, a gas phase method, a plasma and laser using method, and the like. For example, the nickel nano particles may be synthesized on an organic solvent including a surfactant. The synthesized nickel nano particles may be easily dispersed by a nonpolar solvent and are added with a polar solvent such as alcohol, acetone, and the like, and recovered in a power form by a centrifugal separator.
However, the method for synthesizing metal nano particles may relatively easily remove the organic solvent and the surfactant among the impurities remaining on the surfaces of the metal nano particles but may hardly remove the organic matters among the impurities. In particular, when a metal salt including chloride ion is used as a reacting precursor, the chloride ion adhered on the surfaces of the synthesized metal nano particles may not easily be removed. The impurities such as chloride ion, and the like, degrade the purity of the metal nano particles and when intending to form a fine electrode that is a chip component by using the low-purity metal nano particles, the electrode characteristics are deteriorated.

RELATED ART DOCUMENT

Patent Document

(Patent Document 1) Korean Patent Laid-Open Publication No. 2001-0110693

SUMMARY OF THE INVENTION

An object of the present invention is to provide metal nano particles having high purity and a method for surface treating metal nano particles.
Another object of the present invention is to provide synthesized metal nano particles having low impurity concentration and a method for surface treating metal nano particles capable of effectively removing the impurities remaining on the surfaces of metal nano particles.
Still another object of the present invention is to provide metal nano particles having low chloride ion concentration and a method for surface treating metal nano particles capable of effectively removing the chloride ions remaining on surfaces of the synthesized metal nano particles.
According to an exemplary embodiment of the present invention, there is provided a method for surface treating metal nano particles, including: surface treating metal nano particles with an alkanol amine containing solution.
The surface treating of the metal nano particles may include removing chloride ion adhered on the surfaces of the metal nano particles with the alkanol amine.
The surface treating of the metal nano particles may further include substituting chloride ion adhered on the surfaces of the metal nano particles into the alkanol amine.
The surface treating of the metal nano particles may further include: preparing a clean solution containing at least one of ethanolamine, diethanaolamine, and triethanolamine; and preparing a mixing solution by mixing the metal nano particles with the cleaning solution.
A concentration of the alkanol amine of the solution may be 10 wt % or more.
The method for surface treating metal nano particles may further include: cleaning the metal nano particles with alcohol or toluene to remove a surfactant on the surfaces of the metal nano particles.
The method for surface treating metal nano particles may further include: drying the metal nano particles.
After the drying of the metal nano particles, the concentration of the chloride ion on the surfaces of the metal nano particles measured by using ion chromatography may be less than 100 ppm.
After the drying of the metal nano particles, the concentration of the chloride ion on the surfaces of the metal nano particles measured by using ion chromatography may be less than 10 ppm.
The metal nano particles may be surface-treated with an alkanol amine containing solution and after the metal nano particles are dried, the concentration of the chloride ion on the surfaces of the metal nano particles measured by using ion chromatography may be less than 100 ppm.
The concentration of the chloride ion may be less than 10 ppm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart illustrating a method for surface treating metal nano particles according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram for describing a process of surface treating metal nano particles according to the exemplary embodiment of the present invention.

FIG. 3 is a diagram illustrating a multi-layer ceramic capacitor manufactured by using nickel nano particles to which the method for surface treating metal nano particles according to the exemplary embodiment of the present invention is applied.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various advantages and features of the present invention and methods accomplishing thereof will become apparent from the following description of embodiments with reference to the accompanying drawings. However, the present invention may be modified in many different forms and it should not be limited to the embodiments set forth herein. These embodiments may be provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals throughout the description denote like elements.
Terms used in the present specification are for explaining the embodiments rather than limiting the present invention. Unless explicitly described to the contrary, a singular form includes a plural form in the present specification. The word “comprise” and variations such as “comprises” or “comprising,” will be understood to imply the inclusion of stated constituents, steps, operations and/or elements but not the exclusion of any other constituents, steps, operations and/or elements.
Hereinafter, metal nano particles and a method for surface treating metal nano particles according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a flow chart illustrating a method for surface treating metal nano particles according to an exemplary embodiment of the present invention and FIG. 2 is a diagram for describing a principle of surface treating metal nano particles according to the exemplary embodiment of the present invention.
Referring to FIGS. 1 and 2, the method for surface treating metal nano particles according to the exemplary embodiment of the present invention may include removing impurities 120 remaining on surfaces of synthesized metal nano particles 110 (S110), treating the metal nano particles 110 with an alkanol amine 130 containing solution (S120), and drying the metal nano particles 110 (S130).
The metal nano particles 110 may be prepared by using various methods of synthesizing nano particle. For example, various kinds of the metal nano particles 110 may be prepared by using any one of a gas phase method, a liquid phase method, and a plasma and laser using method. As an example, the synthesizing of the metal nano particles 110 may include preparing nickel nano particles using a metal salt including chloride ion as a reacting precursor. Various kinds of impurities 120 may remain in the synthesized metal nano particles 110 in a form in which the impurities 120 are adhered on the surfaces of the metal nano particles 110. The impurities 120 may include an organic solvent, a surfactant, organic matters, and the like. The organic matters may include chloride ion.
The impurities 120 remaining on the surfaces of the metal nano particles 110 may be removed (S110). The removing of the impurities 120 may be performed by treating the metal nano particles 110 with alcohol or toluene. The organic solvent or the surfactant among the impurities 120 may be removed regardless of polarity or non-polarity during the process of treating the metal nano particles 110 with alcohol or toluene. However, it may be difficult to remove the organic matters among the impurities only by the treatment using the alcohol or the toluene. The organic matters adhered on the surfaces of the metal nano particles 110 may degrade the purity of the metal nano particles 110.
Therefore, the metal nano particles 110 may be surface-treated by using the alkanol amine 130 (S120). The surface treating of the metal nano particles 110 may be provided to remove the organic matters among the impurities 120 adhered on the surfaces of the metal nano particles 110. In more detail, in the surface treating of the metal nano particles 110 using the alkanol amine 130, the metal nano particles 110 may be mixed with a cleaning solution. Therefore, the chloride ion that is the organic matters adhered on the surface of the metal nano particles 110 is substituted into the alkanol amine 130, such that the chloride ion may be removed from the metal nano particles.
Here, as the cleaning solution, a solution including at least one of ethanolamine (EA), diethanolamine (DEA), triethanolamine (TEA) may be used. Further, the cleaning solution may further be added with alcohol such as ethanol. In this case, the cleaning solution may be controlled so that the concentration of the alkanol amine becomes at least 10 wt % or more. When the concentration of the alkanol amine is less than 10 wt %, the removal efficiency of the chloride ion is low, such that it may be difficult to expect the high removal efficiency of impurities.
Meanwhile, the surface treating of the metal nano particles 110 (S120) may further include heating a mixing solution prepared by adding the cleaning solution to the metal nano particles 110 at a predetermined temperature. The heating temperature of the mixing solution may be approximately 60° C. to 100° C. In particular, when the alcohol is added to the mixing solution, the heating temperature of the mixing solution may be higher than 78° C. that is a boiling point of the alcohol. However, a substitution reaction between the alkanol amine 130 and the chloride ion may be performed without heating the mixing solution, such that the heating of the mixing solution may be optionally performed.
Further, the metal nano particles 110 may be dried (S130). The drying of the metal nano particles 110 may be for removing the alkanol amine 130 adhered on the surfaces of the metal nano particles 110. The drying of the metal nano particles 110 may include the heat treating of the metal nano particles 110 at a temperature of at least 50° C. or more. Therefore, the alkanol amine 130 adhered to the metal nano particles 110 is dried and removed, such that the metal nano particles 110 having chloride ion concentration less than approximately 100 ppm can be obtained. In particular, the method for surface treating metal nano particles according to the exemplary embodiment of the present invention can obtain the high-purity metal nano particles 110 having the chloride ion concentration of approximately 10 ppm or less, more preferably, less than 5 ppm.

EXAMPLE 1

After the metal nano particles were synthesized, the synthesized metal nano particles were each cleaned with ethanol twice and toluene twice, respectively and were added to a cleaning solution formed of triethanol amine and ethanol to prepare the mixing solution. The mixing solution was heated at a temperature of 80° C. Further, after the metal nano particles were dried, the amount of chloride ion remaining on the surfaces of the nano particles was analyzed using ion chromatography. The following Table 1 shows the removal effect of chloride ion over the surface treating time of a triethanol amine containing solution as described above.

	TABLE 1

		Chloride Ion
	Division	Concentration (ppm)

	Prior to surface treating	1780
	with alkanol amine
	After 30 minutes of surface	5.6
	treating with alkanol amine
	After 10 hours of surface	2.3
	treating with alkanol amine

As described above, the final chloride ion concentration of the metal nano particles which are surface treated with the alkanol amine containing cleaning solution shown the removal ratio of 99% or more than that of the first metal nano particles. That is, the alkanol amine containing cleaning solution may show the removal ration of the high chloride ion of the metal nano particles only by the surface treatment for a short time of about 30 minutes, such that it was shown that the manufacturing process yield of the nano particles having high purity may be significantly improved. In particular, the chloride ion concentration of the metal nano particles may be reduced less than 10 ppm only with the surface treating of 30 minutes and the chloride ion concentration may be reduced less than 5 ppm.
As described above, the method for surface treating metal nano particles according to the exemplary embodiment of the present invention can effectively remove the chloride ion that is difficult to be relatively removed among the impurities 120 adhered on the surface of the synthesized metal nano particles 110 with the alkanol amine solution. In particular, the exemplary embodiment of the present invention may remove the chloride ion of 99% or more within the relatively short process time, thereby significantly improving the surface treating processing efficiency. Therefore, the method for surface treating metal nano particles to the exemplary embodiment of the present invention surface-treats the synthesized metal nano particles by using the alkanol amine solution to effectively remove the chloride ion that is difficult to be relatively removed among the impurities remaining on the surfaces of the synthesized metal nano particles, thereby obtaining the high-purity metal nano particles having the chloride ion concentration of approximately 100 ppm, preferably, less than 5 ppm.
To be continued, as described above, various applications of the metal nano particles 110 from which the impurities are removed by the surface treating method according to the exemplary embodiment of the present invention will be described in detail.
The surface-treated metal nano particles according to the exemplary embodiment of the present invention may be used as a material for forming internal wirings of the electronic circuit. In particular, in the case in which the metal nano particles are nickel nano particles, the nickel nano particles have the relatively higher purity and tap density and thus, may be suitably used as a material for forming the electrode of the multi-layer ceramic capacitor (MLCC) that is gradually small and thin in recent.
FIG. 3 is a diagram illustrating a multi-layer ceramic capacitor manufactured by using nickel nano particles to which the method for surface treating metal nano particles according to the exemplary embodiment of the present invention is applied. Referring to FIG. 3, a nickel paste may be prepared by adding an organic binder and an organic solvent to the nickel nano particles obtained by synthesizing the nickel nano particles and performing the surface treating described with reference to FIGS. 1 and 2 on the synthesized nickel nano particles. An example of the organic binder may include ethyl cellulose, and the like, and an example of the organic solvent may include terpineol, dihydroxy terpineol, 1-octanol kerosene, and the like. In this case, the contents of the nickel paste may be controlled to have 40 wt % to 60 wt % of nickel nano particles, 0.8 wt % to 4 wt % of organic binder, and 40 wt % to 60 wt % of organic solvent. Here, the conductive paste according to the exemplary embodiment of the present invention may further include any one additives among a plasticizer, an anti-viscosity agent, and a dispersant.
Further, after the plurality of dielectric sheets 20 are prepared, predetermined internal electrodes 30 of the metal paste may be formed on each dielectric sheets 20 by a screen printing method. The dielectric sheets 20 are laminated and burned, thereby manufacturing the laminate 40. External electrodes 50 electrically connected with the internal electrodes 30 may be formed at both ends of the laminate 40. In this case, the external electrode 50 may be formed using the nickel paste. When the external electrode 50 is formed of the nickel paste, a separate plating process for forming the external electrode 50 may not be performed. The multi-layer ceramic capacitor 10 having the high electrode characteristics may be manufactured by the foregoing process.
The foregoing exemplary embodiment of the present invention describe, by way of example, the case in which the metal nano particles according to the present invention are applied to the chip component elements such as the multi-layer ceramic capacitor, but the metal nano particles according to the present invention can be applied to various fields. As another example, the metal nano particles may be used as a catalyst. In more detail, the metal nano particles may be used as a catalyst for a fuel cell, a hydrogenation catalyst, a substitute catalyst of Pt in various chemical reactions, and the like.
According to the exemplary embodiments of the present invention, the chloride ion impurities that are difficult to be relatively removed are treated with the alkanol amine solution so as to effectively remove the chloride ion impurities, thereby obtaining the metal nano particles having the high purity.
According to the exemplary embodiments of the present invention, the method for surface treating metal nano particles surface-treats the synthesized metal nano particles by using the alkanol amine solution to effectively remove the chloride ion that is difficult to be relatively removed among the impurities remaining on the surfaces of the synthesized metal nano particles, thereby obtaining the metal nano particles having high purity.
The above detailed description exemplifies the present invention. Further, the above contents just illustrate and describe preferred embodiments of the present invention and the present invention can be used under various combinations, changes, and environments. That is, it will be appreciated by those skilled in the art that substitutions, modifications and changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents. Although the exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Therefore, the detailed description of the present invention does not intend to limit the present invention to the disclosed embodiments. Further, it should be appreciated that the appended claims include even another embodiment.

Claims

What is claimed is:

1. A method for surface treating metal nano particles, comprising:

surface treating metal nano particles with an alkanol amine containing solution.

2. The method according to claim 1, wherein the surface treating of the metal nano particles includes removing chloride ion adhered on the surfaces of the metal nano particles with the alkanol amine.

3. The method according to claim 1, wherein the surface treating of the metal nano particles further includes substituting chloride ion adhered on the surfaces of the metal nano particles into the alkanol amine.

4. The method according to claim 1, wherein the surface treating of the metal nano particles further includes:

preparing a clean solution containing at least one of ethanolamine, diethanaolamine, and triethanolamine; and

preparing a mixing solution by mixing the metal nano particles with the cleaning solution.

5. The method according to claim 1, wherein a concentration of the alkanol amine of the solution is 10 wt % or more.

6. The method according to claim 1, further comprising cleaning the metal nano particles with alcohol or toluene to remove a surfactant on the surfaces of the metal nano particles.

7. The method according to claim 1, further comprising:

drying the metal nano particles.

8. The method according to claim 7, wherein after the drying of the metal nano particles, the concentration of the chloride ion on the surfaces of the metal nano particles measured by using ion chromatography is less than 100 ppm.

9. The method according to claim 8, wherein after the drying of the metal nano particles, the concentration of the chloride ion on the surfaces of the metal nano particles measured by using ion chromatography is less than 10 ppm.

10. Metal nano particles, wherein the metal nano particles are surface-treated with an alkanol amine containing solution and after the metal nano particles are dried, the concentration of the chloride ion on the surfaces of the metal nano particles measured by using ion chromatography is less than 100 ppm.

11. The Metal nano particles according to claim 10, wherein the concentration of the chloride ion is less than 10 ppm.