Patent Application
20070244220
The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:
Hereinafter, the present invention will be explained in more detail.
The dispersion adjuvant for metal nanoparticles according to the present invention is used in combination with a dispersant so as to inhibit the metal nanoparticles from agglomerating and to improve dispersibility of the metal nanoparticles.
Generally, metal nanoparticles forming metal nanoink tend to agglomerate or form lumps in a solvent, thereby showing poor dispersibility, and settle in the solvent in the form of agglomerates, resulting in degradation of usefulness of metal nanoink. Therefore, a dispersant having a good affinity to a solvent and capable of well dispersing the metal nanoparticles in the solvent is used to form metal nanoink.
Dispersants that may be used widely in the art include polymeric dispersants having oxygen (O) atom and/or nitrogen (N) atom. In such dispersants, oxygen atoms and nitrogen atoms have unpaired electrons, and thus the dispersants are capable of interaction with a metal, even though they are not bound to the metal. Such interaction makes it possible to disperse metal nanoparticles in a solvent.
The dispersion adjuvant according to the present invention comprises an amide derivative having hetero atoms, such as oxygen atoms and nitrogen atoms, having unpaired electrons. Therefore, the hetero atoms, such as oxygen atoms and nitrogen atoms, contained in the dispersion adjuvant according to the present invention, are capable of interaction with metal nanoparticles. Such interaction between the dispersion adjuvant and the metal nanoparticles serves to increase the interaction between a dispersant and metal nanoparticles, and thus facilitates dispersion of the metal nanoparticles in a solvent.
As mentioned above, the dispersion adjuvant for metal nanoparticles according to the present invention comprises an amide backbone-containing amide derivative represented by the above Formula 1 or Formula 2.
Non-limiting examples of the amide derivative represented by Formula 1 include 2-pyrrolidinone, N-methyl-2-pyrolidone (NMP, 1-methyl-2-pyrrolidinone), 3-methyl-2-pyrrolidinone, 5-methyl-2-pyrrolidinone, 1-butyl-2-pyrrolidinone, 3,3,5-trimethyl-2-pyrrolidinone, 1,5-dimethyl-2-pyrrolidinone, 1-phenyl-2-pyrrolidinone, 3-bromo-1-phenyl-2-pyrrolidinone, 3-amino-2-pyrrolidinone, N-(3-aminopropyl)-2-pyrrolidinone, 4-hydroxy-2-pyrrolidinone, 1-(hydroxymethyl)-2-pyrrolidinone, 5-(hydroxymethyl)-2-pyrrolidinone, 1-benzyl-2-pyrrolidinone, 1-(2-hydroxybenzyl)-2-pyrrolidinone, 3-azabicyclo[3.3.0]octan-2-one, or the like.
Non-limiting examples of the amide derivative represented by Formula 2 include N,N-dimethylformamide, N,N-dimethylacetamide, 2-chloro-N,N-dimethylacetamide, N-ethenyl-N-methylacetamide, N,N-dimethylpropanamide, N,N-2-trimethylpropanamide, N,N-dimethyl-2-oxo-acetamide, or the like.
Additionally, the amide derivative is present preferably in a liquid state at room temperature, since a dispersion adjuvant having good affinity and compatibility to a solvent provides high quality.
The metal nanoink according to the present invention comprises: a dispersant; a dispersion adjuvant for metal nanoparticles comprising the amide derivative according to the present invention; metal nanoparticles; and a non-aqueous solvent.
The dispersion adjuvant may be a compound that belongs to the same class as the functional group or terminal group contained in the dispersant. Otherwise, the dispersant may include the amide group of the dispersion adjuvant as a functional group or terminal group. In other words, the dispersion adjuvant may be a compound containing the functional group or terminal group contained in the dispersant.
For example, when the dispersant is polyvinyl pyrrolidone (PVP), each unit of polyvinyl pyrrolidone has a pyrrolidyl group, and thus a compound that belongs to the same class as pyrrolidyl group, such as N-methyl-2-pyrrolidone, may be used as the dispersion adjuvant. However, the scope of the present invention is not limited thereto. If the dispersant contained in metal nanoink is a polymer, such as polyvinyl pyrrolidone, having a high molecular weight, the polymer may have a limitation in serving as a dispersant for metal nanoparticles due to its functional groups or terminal groups (e.g. pyrrolidyl groups) adjacent to each other. However, when a dispersant adjuvant satisfying the above-mentioned requirement according to the present invention is contained in metal nanoink in combination with the dispersant, the dispersant adjuvant, which has a low molecular weight and is capable of interaction with metal nanoparticles, partially substitutes for the functions of the dispersant while increasing the interaction between the dispersant and the metal nanoparticles, thereby improving dispersion of the metal nanoparticles in a solvent.
The dispersion adjuvant may be used in metal nanoink in an amount of 0.1˜15 parts by weight per 100 parts by weight of the total metal nanoink. When the dispersion adjuvant is used in an amount less than 0.1 parts by weight, it is not possible to sufficiently improve dispersion of metal nanoparticles in a solvent. If the dispersion adjuvant is used in an amount greater than 15 parts by weight, the solid content (metal nanoparticles) decreases accordingly, resulting in an undesired drop in conductivity.
There is no particular limitation in the dispersant, as long as the dispersant is a currently used dispersant for metal nanoink. Particularly, dispersants that may be used in the present invention include polymeric dispersants containing oxygen atoms (O) and/or nitrogen atoms (N) and having a molecular weight of 2000 or more.
Non-limiting examples of the polymeric dispersants include polyvinyl pyrrolidone (PVP), polyethylene imine (PEI), polymethyl vinyl ether (PMVE), polyvinyl alcohol (PVA), polyoxyethylene alkyl phenyl ether, polyethylene sorbitan monostearate or derivatives thereof. The above dispersants may be used alone or in combination.
Additionally, there is no particular limitation in the amount of the dispersant in the metal nanoink according to the present invention. Preferably, the dispersant is used in an amount of 0.01˜10 parts by weight based on 100 parts by weight of the total metal nanoink. If the dispersant is used in an amount less than 0.01 parts by weight based on 100 parts by weight of the metal nanoink, it is not possible to sufficiently disperse metal nanoparticles in a solvent. If the dispersant is used in an amount greater than 10 parts by weight, the solid content (metal nanoparticles) decreases accordingly, resulting in an undesired drop in conductivity and increase in viscosity.
The metal nanoparticles that may be used in the present invention include at least one particles selected from the group consisting of: transition metals selected from Ag, Au, Pd, Pt, Ni, Cu, Cr, Al, W, Zn, Fe and Pb; alloys of the transition metals; sulfides of the transition metals; carbides of the transition metals; oxides of the transition metals; nitrides of the transition metals; and salts of the transition metals.
Additionally, the metal nanoparticles are used in an amount of 0.1˜90 parts by weight, preferably 0.1˜70 parts by weight, based on 100 parts by weight of the total metal nanoink. If the metal nanoparticles are used in an amount less than 0.1 parts by weight based on 100 parts by weight of the metal nanoink, it is not possible to form an interconnection line or film having a sufficient thickness and conductivity. If the metal nanoparticles are used in an amount greater than 90 parts by weight, the resultant metal nanoink has a decreased flowability and shows low dispersibility in a solvent.
Further, there is no particular limitation in the non-aqueous solvent in the metal nanoink according to the present invention, as long as the solvent can impart flowability to the ink and is a currently used non-aqueous solvent for ink. Non-limiting examples of the non-aqueous solvent include alcohols, glycols, polyols, glycol ethers, glycol ether esters, ketones, hydrocarbons, lactates, esters, aprotic sulfoxides, nitriles, or the like.
Particular examples of the non-aqueous solvent that may be used in the metal nanoink according to the present invention include methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, ethylene glycol, propylene glycol, glycerol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol propyl ether, ethylene glycol monophenyl ether, ethylene glycol monoisopropyl ether, THF, propylene glycol methyl ether acetate, methyl isobutyl ketone, methyl ethyl ketone, hexadecane, pentadecane, tetradecane, tridecane, dodecane, undecane, decane, nonane, octane, heptane, hexane, xylene, toluene, benzene, DMSO, acetonitrile, or the like. However, the scope of the present invention is not limited thereto.
Additionally, the above non-aqueous solvents may be selected considering the viscosity, dispersibility and solvent volatility of metal nanoink to be provided, and may be used alone or in combination.
The metal nanoink according to the present invention may be used as ink for circuit interconnection.
For example, the metal nanoink is applied to an ink jet printing process using an ink jet nozzle for ejecting the ink, and then heat treatment is performed to form metal interconnection lines. The above heat treatment may be carried out at a temperature of 150˜500° C. Such heat treatment allows the dispersant and the dispersant adjuvant to be pyrolyzed and removed.
Therefore, the present invention also provides a conductive interconnection line or film formed by using the metal nanoink comprising a dispersant, a dispersion adjuvant comprising the amide derivative according to the present invention, metal nanoparticles and a solvent. A circuit comprising the above conductive interconnection line or film is also included in the scope of the present invention.
Reference will now be made in detail to the preferred embodiments of the present invention. It is to be understood that the following examples are illustrative only and the present invention is not limited thereto.
First, 50 wt % of Ag nanoparticles having a D50 of 70 nm and obtained by the polyol process was provided. Then, 1 wt % of polyvinyl pyrrolidone (PVP) having a molecular weight of 55,000 was provided as a dispersant, and 15 wt % of N-methyl-2-pyrrolidone (NMP) was provided as a dispersion adjuvant. Further, a mixed solvent containing 15 wt % of 2-phenoxyethanol, 10 wt % of isopropyl glycol, 4 wt % of glycerol and 5 wt % of ethanol was provided. The above materials were mixed rigorously by using a shaker at room temperature (25° C.) for 24 hours to provide silver nanoink.
Ag nanoink was provided in the same manner as described in Example 1, except that N-methyl-2-pyrrolidone (NMP) was not used and 2-phenoxyethanol was further used.
Each Ag nanoink obtained from Example 1 and Comparative Example 1 was stored in an oven at 50° C. for 3 days, while measuring variations in viscosity and TGA. The results are shown in the following Table 1 and
As can be seen from the variations in TGA of each nanoink with time (Table 1 and
Therefore, it can be seen from the above results that the silver nanoink using NMP as a dispersion adjuvant according to Example 1 allows a greater amount of silver nanoparticles to be dispersed in a solvent and has a higher solid content, when compared to the silver nanoink containing no NMP according to Comparative Example 1. Also, the silver nanoink according to Example 1 inhibits metal nanoparticles from agglomerating among themselves. Further, because the silver nanoink according to Example 1 has an increased solid content when compared to the silver nanoink according to Comparative Example 1, metal lines formed by using the silver nanoink according to Example 1 can provide improved conductivity.
The dispersion adjuvant according to the present invention helps metal nanoparticles to be dispersed in a solvent in the presence of a dispersant, inhibits metal particles from agglomerating among themselves, and increases the content of metal nanoparticles in a solvent. Additionally, interconnection lines formed by using the nanoink according to the present invention have an increased content of metal per unit area, and thus provide improved conductivity.
Although several preferred embodiments of the present invention have been described 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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0033207 | Apr 2006 | KR | national |
