KR20120138703A - Conductive metal nano particle ink and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A conductive metal nanoparticle ink with enhanced dispersibility and a manufacturing method thereof are provided to enhance dispersibility, jettability and to lower resistivity. CONSTITUTION: A conductive metal nanoparticle ink comprises 10-90 weight% of metal nanoparticles obtained through electrolysis and 10-90 weight% of ink solvent. In the metal nanoparticle, dispersant is the capped. A manufacturing method of the conductive metal nanoparticle ink comprises the following steps: separating metal nanoparticles after removing electrolyte and dispersant from metal nanoparticle colloid solution(s12); and dispersing and pulverizing the metal nanoparticles by putting the metal nanoparticle into bead mill with ink solvent(s14). [Reference numerals] (AA) Start; (S11) Preparing metal nanoparticle contained colloid solution; (S12) Centrifuging; (S13) Drying; (S14) Pulverizing; (S15) Adding ink solvent and auxiliary solvent; (S16) Homomixing(simple agitating); (S17) Bead milling; (S18) Fractional distillation; (S19) Filtering; (S20) Ink completion

Description

Conductive Metal Nano Particle Ink and Manufacturing Method

The present invention relates to a conductive metal nanoparticle ink and a method for manufacturing the same, and in particular, to produce a conductive metal nanoparticle ink having excellent dispersibility, jetting property, and low resistivity in an environmentally friendly and easy way using a bead mill solution dispersion method. The present invention relates to a conductive metal nanoparticle ink using a bead mill solution dispersion method and a method of manufacturing the same.

The pattern forming method using photolithography has an advantage of realizing a microcircuit, but has a disadvantage in that a process is complicated and expensive equipment is required. In addition, the screen printing method using the silver paste has the advantage that the process is simple, but there is a disadvantage that it is difficult to implement a circuit having an ultra-fine pattern to continue to replace the screen.

The laser transfer method is a method in which expensive silver is coated on the entire surface of a circuit, and then a required circuit is drawn by a laser, which consumes silver, which is a wiring material.

In contrast, a method of patterning circuit wiring by a non-contact direct printing method using inkjet is a technique of forming a wiring by directly discharging a predetermined amount of ink to an accurate position through an inkjet head. It is attracting attention as the next-generation wiring method because of its simple process and short manufacturing time.

Accordingly, ink development using metal nanoparticles has recently been made, and in the electronic industry, conductive paste or conductive nano ink technology has recently gained great attention in terms of productivity, cost reduction, and environment due to the large size of the display industry and the simplification of processes. .

Such conductive metal nano inks require uniform particle size and excellent dispersibility, and metal nano particles of uniform particle size used in the metal nano ink are mostly made by a chemical method that is dispersed and synthesized in a solution. As such, in order to make the colloidal solution in which the metal nanoparticles are dispersed into a conductive nano ink, dispersion of the metal nanoparticles into each solvent is important.

In general, nanoparticle inks having excellent dispersibility, jetting property, and electrical conductivity are using a method of fractional distillation after mechanical stirring by mixing an ink solvent and a dispersion solvent.

For example, in order to prepare a conventional high concentration of conductive silver nanoparticle ink, the silver nanoparticles or colloidal solution is dispersed by stirring in a dispersion solvent, and then the ink solvent is re-introduced and stirred, and the dispersion solvent is classified through fractional distillation. A method of dispersing particles using two-step mechanical agitation is used (see Korean Patent Publication No. 2008-98256).

However, such a conventional method for preparing metal nanoinks for inkjet is a limited solvent exchange method in which the original polarities of silver nanoparticles or colloidal solutions, namely, aqueous systems are aqueous and organic systems are only dispersed into organic systems, and vice versa. It has the disadvantage of having a complicated process procedure as well as adversely affecting it.

In addition, since the boiling point for the fractional distillation of the dispersion solvent and the ink solvent must be considered, the conventional method of manufacturing the metal nano ink has to be selected for the solvent.

In addition, the conventional use of a large amount of the dispersion solvent is not only a wastewater treatment problem occurs in the washing process, but also has a lot of washing process, there is a problem of losing the metal powder only in the washing process.

On the other hand, the oil-based metal ink has the advantages of smaller nanoparticle size, easier manufacturing of high concentration, and continuous ejection from the head, compared to the water-based metal ink, but the crack of the wiring of the printed image is severe and the line width is not uniform. Because of this, surface treatment is essential and has a disadvantage of high firing temperature.

In Korean Patent Publication No. 2008-102098, in order to solve this problem, by selecting an ink additive soluble in a lipophilic solvent and optimizing the composition of the metal ink to increase the adhesive strength with the substrate when forming the wiring by inkjet printing to prevent cracking As a non-aqueous metal ink composition which hardens well at low temperature, the technique which disperse | distributed metal nanoparticle to the non-aqueous organic solvent with an additive is proposed.

In the conventional non-aqueous metal ink composition, metal nanoparticles synthesized in a non-aqueous solution are used for compatibility with a solvent by using a non-aqueous organic solvent.

However, these conventional inkjet metal ink compositions have complicated process procedures and generation of waste water.

Korean Laid-Open Patent No. 2008-98256 Korean Laid-Open Patent No. 2008-102098

Accordingly, the present invention has been made in view of the above-described problems of the prior art, the purpose of which is the conductive metal nanoparticles having excellent dispersibility, jetting property, and low specific resistance in an environmentally friendly and easy way using bead mill solution dispersion method The present invention provides a conductive metal nanoparticle ink using a bead mill solution dispersion method capable of producing an ink, and a method for producing the ink.

Another object of the present invention is to simplify the manufacturing process by using only the ink solvent, without the use of a dispersion solvent, and to solve the problem of wastewater treatment and the loss of a lot of metal powder in the washing process according to the conventional use of a large amount of dispersion solvent The present invention provides a conductive metal nanoparticle ink using a bead mill solution dispersion method that can be removed, and a method of manufacturing the same.

It is still another object of the present invention to provide a conductive metal nanoparticle ink using a bead mill solution dispersion method that is not limited to the selection of an organic or aqueous solvent by the strong dispersing force of the bead mill and a method for producing the same.

Another object of the present invention is to provide a conductive nanoink manufacturing method having excellent dispersibility using a colloidal solution in which metal nanoparticles are dispersed.

Another object of the present invention is to provide a high concentration of conductive metal nanoparticle ink which can be used as a conductive paste, and a method of manufacturing the same.

In order to achieve the above object, the present invention provides a conductive metal nanoparticle ink comprising 10 to 90% by weight of the metal nanoparticles and 10 to 90% by weight of the ink solvent.

According to another feature of the invention, the present invention comprises the steps of removing the electrolyte and dispersant from the metal nanoparticle colloidal solution obtained through electrolysis and separating the metal nanoparticles; And dispersing and pulverizing the metal nanoparticles in the ink solvent by injecting the metal nanoparticles into the bead mill together with the ink solvent to provide a method for producing a conductive metal nanoparticle ink.

According to another feature of the invention, the present invention comprises the steps of separating the metal nanoparticles by removing the electrolyte and dispersant from the metal nanoparticle colloidal solution obtained through electrolysis by centrifugation; Adding an ink solvent to the metal nanoparticles and pre-dispersing the mixture through first stirring; A bead mill step of uniformly dispersing and pulverizing the metal nanoparticles in the ink solvent by adding the first stirring solution to the bead mill; And extracting the metal nanoink by removing the auxiliary solvent through the fractional distillation of the solution dispersed and pulverized through the bead mill.

Hereinafter, the conductive nanoink of the present invention and a manufacturing method thereof will be described in more detail.

The conductive metal nanoparticle ink according to the present invention contains 10 to 90% by weight of the metal nanoparticles and 10 to 90% by weight of the ink solvent.

First, when the conductive metal nanoparticle ink contains less than 10% by weight of the metal nanoparticles, when the conductive printed circuit pattern is formed on the substrate by inkjet printing using ink, the content of the conductive nanoparticles is so small that the resistance of the circuit pattern is reduced. This increasing problem may occur, and the viscosity is too high when containing more than 70% by weight of the metal nanoparticles inkjet printing is impossible.

Ink having a concentration of 70 to 90 wt% has high viscosity and is not jetted, and may be applied as a conductive paste for screen printing.

In addition, when the metal nanoparticles are prepared through electrolysis, the metal nanoparticles are any one selected from the group consisting of Ag, Pt, Au, Mg, Al, Zn, Fe, Cu, Ni and Pd or It may be made of two or more alloys.

The metal nanoparticles used in the conductive metal nanoparticle ink are preferably silver (Ag) nanoparticles in consideration of the material cost and the electrical conductivity and the degree of oxidation.

The ink is preferably prepared by adding an auxiliary solvent to the ink solvent, so that the bead mill process is performed, and then, dispersion is performed in the ink solvent, followed by fractional distillation in a subsequent process. In addition, a low concentration ink having a low content of metal nanoparticles may be obtained by diluting a high concentration ink.

In addition, when the content of the metal nanoparticles in the ink is 10 to 50% by weight, it shows excellent jetting property even when a head of 30 pl (pico liter) nozzle size is used for inkjet printing, and the content of the metal nanoparticles is 10 In the case of 40 wt% to 40 wt%, excellent jetting property is shown in the head of the 5 pl nozzle size.

The metal nanoparticles may be prepared through electrolysis, or may be obtained by a chemical method or a mechanical method in addition to the electrolysis method, and those prepared through electrolysis are preferable in view of the size or uniformity of the nanoparticles.

In addition, when the metal nanoparticles are prepared through electrolysis, they are present in a colloidal state in the electrolyte in a form surrounded by a dispersant. In this case, when the metal nanoparticles solidify the colloidal solution in which the metal nanoparticles are dispersed, the conductive nanoparticle ink is prepared according to the centrifugation process, and inkjet printing adversely affects the electrical conductivity when the circuit wiring is formed. The impact can be removed most of the dispersant can be expected to improve the electrical conductivity.

Therefore, the dispersing agent surrounding the metal nanoparticles contained in the conductive nanoparticle ink is preferably included in the range of 1 to 10% by weight, when less than 1% by weight may cause a problem in the dispersion of the ink. In addition, when the metal nanoparticles are prepared through electrolysis, the high concentration ink having a high content of the metal nanoparticles also increases the content of the dispersant. In this case, the dispersant is undesirable due to the aggregation of the dispersant and the increase in the specific resistance when it exceeds 10% by weight.

On the other hand, in the case of using the colloidal solution in which the metal nanoparticles obtained by the electrolysis method is dispersed as a starting material, the surface capping metal nanoparticles can be easily dispersed in a solvent to be easily prepared in a dispersible ink, It shows dispersion stability that does not aggregate for a long time even after being prepared with ink.

Solvents that can be used for ink preparation include ethyl alcohol, methyl alcohol, isopropyl alcohol, 2-methoxy ethanol, propyl alcohol, Alcohols such as pentyl alcohol, hexyl alcohol, butyl alcohol, octyl alcohol, ethylene glycol, diethylene glycol and triethylene Triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, triglycol monomethyl ether (TGME: Triethylene Glycol Monomethyl Ether Glycols such as propylene glycol methyl ether acetate, glycerine, acetone, formamide and methyl ethyl ketone. Methyl ethyl ketone, methane, ethane, ethane, propane, butane, pentane, hexane, heptane, octane, nonan ), Decane, Undecane, Dodecane and other alkyl-based, and cyclohexanone (Cyclohexanone) such as most solvents are used.

The conductive nanoparticle ink may have different dispersion states, specific resistance, and jetting properties even through the same process depending on the ink solvent and the dispersant.

In addition, especially in polar solvents having a high dielectric constant, good dispersibility for silver nanoparticles is shown.

Hereinafter, the manufacturing method of the said conductive metal nanoparticle ink is demonstrated in detail.

Method for producing a conductive metal nanoparticle ink according to an embodiment of the present invention comprises the steps of removing the electrolyte and dispersant from the metal nanoparticle colloidal solution obtained through electrolysis and separating the metal nanoparticles; And dispersing the metal nanoparticles in the bead mill together with the ink solvent to uniformly disperse and pulverize the metal nanoparticles in the ink solvent.

The metal nanoparticle colloidal solution may be a metal nanoparticle colloidal solution obtained by direct current or alternating current electrolysis.

In this case, the separation or removal of the electrolyte and the dispersant from the metal nanoparticle colloidal solution may use a centrifugal separation method. Since the obtained metal nanoparticles cannot be completely removed when the electrolyte and the dispersant are separated or removed by centrifugation, the surface of the particles is capped with a polyacrylic, polyurethane, or polysiloxane-based water-soluble polymer dispersant or water-dispersible polymer dispersant. And remain.

The dispersant is, for example, Disperbyk ™ -111, Byk ™ -154, Disperbyk ™ -180, Disperbyk ™ -182, Disperbyk ™ -190, Disperbyk ™ -190, Disperbyk ™ -192, Disperbyk ™ -193, Disperbyk ™ -2012, Disperbyk ™ -2015, Disperbyk ™ -2090, Disperbyk ™ -2091; Tevo ™ 715w, Tego ™ 735w, Tego ™ 740w ™, Tego ™ 745w ™, Tego ™ 750w, Tego ™ 755w, Tego ™ 775w from Evonik; Solbrise ™ 20000, Solsperse ™ 43000, Solsperse ™ 44000 from Lubrizol; Ciba's EFKA ™ 4585; Dow's Orotan ™ 731A, Orotan ™ 1124; Tween 20, Tween 80 from Aldrich; Any one or two or more selected from the group consisting of polyethylene glycol (PEG) 200, polyvinylpyrrolidone (PVP) 10,000, PVP 55,000, poloxamer 407, and poloxamer 188 It may be a commercial dispersant.

The centrifugation is preferably carried out at 8000 rpm for 4 hours, in which case a yield of 91% or more is obtained.

The viscosity of the ink obtained according to the invention ranges from 10 to 72585 cP and increases in proportion to the content of the metal nanoparticles, ie concentration.

In the case of a high concentration ink having a metal nanoparticle content of 70% by weight, the viscosity shows a range of 5477 to 72585 cP, which is not jettable and can be used for screen printing. In addition, when the ink contains less than 50% by weight of the metal nanoparticles, it shows excellent jetting properties during inkjet printing.

In addition, in preparing the ink, when the metal nanoparticles are added to the bead mill together with the ink solvent, a co-solvent is added as needed, and after the dispersing step, the co-solvent is further removed by fractional distillation. It may include. In this case, the auxiliary solvent preferably has a boiling point lower than that of the ink solvent so that the auxiliary solvent can be removed by fractional distillation.

Further, the auxiliary solvent may be added for supplementation of the prescribed amount when the mixed amount of the metal nanoparticles and the ink solvent to be added to the bead mill is less than the sample prescribed amount to be added to the bead mill. In addition, the auxiliary solvent is a small content of the ink solvent mixed with the metal nanoparticles in the case of high concentration ink is added for smooth transfer when supplying the mixture to the bead mill using a feed pump, or after the metal nanoparticles bead mill equipment after bead milling It can be added as a washing solvent to wash what is attached to it.

The auxiliary solvent is preferably added above the prescribed amount replenishment to supplement the sample when the mixed amount of the metal nanoparticles and the ink solvent is less than the sample amount to be added to the bead mill.

In addition, the auxiliary solvent may be further used as a washing solvent for washing the stirrer after the pre-dispersion step when the pre-dispersion step of grinding and dispersing the metal nanoparticles aggregated by centrifugation in the stirrer with the ink solvent, the beads It may further be used as a washing solvent to wash the bead mill equally after the mill step.

Therefore, it is preferable that the auxiliary solvent used as the prescribed amount replenishment and washing solvent in the ink manufacturing process is more than the prescribed amount replenishment and contains less than three times the sample prescribed amount. It is preferable to add more auxiliary solvents than the prescribed amount for improving the dispersibility of the ink, and when the amount exceeds 3 times the amount specified in the sample, the processing time becomes longer when removed by fractional distillation, and there is a problem that the material cost increases. .

Accordingly, the input amount of the auxiliary solvent is preferably greater than (sample amount to be added to the bead mill— (mixing amount of metal nanoparticles and ink solvent)) and less than three times the sample amount.

The auxiliary solvent may be at least one selected from the group consisting of ethanol, methanol, propanol, isopropanol, acetone, toluene and hexane.

The present invention may further include a pre-dispersion step for pulverizing and dispersing the aggregated metal nanoparticles with the ink solvent and the auxiliary solvent in the step of removing the electrolyte and the dispersant from the metal nanoparticle colloid solution before the dispersion step.

In this case, in the pre-dispersion step, it is preferable to use a stirrer such as a home mixer, a ball mill, or a mechanical stirrer when grinding and dispersing the aggregated metal nanoparticles.

The conductive metal nanoparticle ink obtained according to the manufacturing method may include 10 to 90% by weight of the metal nanoparticles and 10 to 90% by weight of the ink solvent. In this case, when the solvent dilution method is used without the fractional distillation, for example, 10 to 80% by weight ink may be prepared using the 90% by weight ink.

The step of uniformly dispersing and pulverizing the powdered metal nanoparticles into the bead mill together with the ink solvent is preferably performed at 500 to 6000 rpm for 1 to 10 hours in terms of dispersion or crushing.

That is, the bead milling step of dispersing the metal nanoparticles in the ink solvent by using the bead mill is a precipitate present in less than 1 hour, it is possible to manufacture the ink without the precipitate from 1 hour, more than 10 hours In this case, a problem of aggregation occurs, and an ink having the best jetting property is obtained at 6 hours.

In this case, it is preferable that the ratio of the mixing amount of the metal nanoparticles and the ink solvent and bead added to the bead mill is set to 3: 7.

Three kinds of beads used for bead milling are used, such as 100, 50, and 30 um, and the smaller the size of the beads, the better the ink having excellent dispersing force and jetting property.

The amount of beads put into the bead mill is 400 g is the ideal bead amount when the sample standard of the bead mill equipment is 1L, and even if too large, the dispersibility is low, the specific resistance is also low when the dispersibility is poor.

In addition, the rotor rotation speed of the bead mill is preferably 500 ~ 6000rpm, if the rpm is too fast can not give enough energy for the crushing metal nanoparticles, there is a problem that the dispersion force is rather falling. If the rotor rotational speed of the bead mill is out of the range of 500 ~ 6000rpm also increases the size of the nanoparticles, the dispersion is lowered and the specific resistance is increased.

As described above, in the present invention, as the uniform and fine nanoparticles are dispersed using the bead mill solution dispersion method, the conductive metal nanoparticle ink having jetting property and low specific resistance can be prepared.

The present invention simplifies the manufacturing process by using only the ink solvent without using a dispersion solvent, and eliminates the problem of wastewater treatment and the loss of many metal nanoparticle powders that occur in the washing process according to the conventional use of a large amount of the dispersion solvent. can do.

In the present invention, when the conductive nanoparticle ink is prepared by solidifying the colloidal solution in which the metal nanoparticles are dispersed, the fineness of the conductive nanoparticle ink is increased by increasing the degree of dispersion of the metal nanoparticles by using bead milling. Dispersion can be expected.

In addition, the present invention is not limited to the selection of an organic or aqueous solvent by the strong dispersing force of the bead mill.

Furthermore, in the present invention, when solidifying the colloidal solution in which the metal nanoparticles are dispersed, most of the dispersant that interferes with the electrical conductivity during sintering can be removed after the conductive nanoparticle ink is prepared by centrifugation and drying. You can expect to improve conductivity.

In addition, since the present invention can be continuously performed when metal nanoparticles are dispersed using bead milling, a high recovery rate can be expected.

Furthermore, the present invention is not limited to the kind of the solution to be initially synthesized, and by solidifying and synthesizing the conductive nanoink, the colloidal solution in which the metal nanoparticles are dispersed can be included, thereby facilitating solvent exchange.

In addition, the present invention can use the colloidal solution in which the metal nanoparticles are initially dispersed, as it is, and the composition is simple and the manufacturing process is simple, so that the conductive metal nanoparticle ink can be manufactured at low cost.

1 and 2 are a process flowchart illustrating a method of manufacturing a conductive metal nanoparticle ink according to the first and second embodiments of the present invention, respectively;
3 is a thermal decomposition graph showing the residual amount of the ink with increasing temperature of the Ag nanoparticle ink to confirm the residual amount of the dispersant,
4 is a graph showing a change in dispersibility according to the amount of beads and the rotor speed of the bead mill;
5 is a graph showing the transmittance and reflectance to determine the dispersion of the conductive metal nanoparticle ink according to the present invention.

Hereinafter, a conductive nanoparticle ink and a method of manufacturing the same according to embodiments of the present invention will be described with reference to the accompanying drawings.

1 and 2 are process flowcharts illustrating a method of manufacturing a conductive metal nanoparticle ink, respectively, according to the first and second embodiments of the present invention.

Referring to FIG. 1, in the method of preparing a conductive metal nanoparticle ink according to the first embodiment of the present invention, preparing a colloidal solution containing metal nanoparticles (S11), an electrolyte of a metal nanoparticle colloidal solution after electrolysis Removing through centrifugation to remove the reducing agent and dispersant (S12), drying the centrifuged metal nanoparticles (S13), grinding the dried metal nanoparticles (S14), ink for ink production After adding the auxiliary solvent for the solvent and the bead mill with the pulverized metal nanoparticle powder to an agitator such as a homomixer (S15), preliminary dispersion, that is, homomixing (simple stirring) (S16), A bead milling step (S17) of the pre-dispersed colloidal sample using a bead mill, removing the auxiliary solvent by fractional distillation (S18).

Thereafter, by removing the auxiliary solvent and filtering nanoparticles or foreign substances or the like having a desired particle size or more as a post-process on the ink in which the conductive metal nanoparticles are dispersed in the ink solvent (S19), the conductive metal nanoparticle ink is obtained ( S20).

Hereinafter, a method of manufacturing the conductive metal nanoparticle ink according to the first embodiment of the present invention will be described in detail for each process.

First, a colloidal solution containing metal nanoparticles is prepared (S11). Colloidal solutions containing the metal nanoparticles can be obtained using, for example, direct current (DC) or alternating current (AC) electrolysis methods. That is, the metal nanocrystal obtained by using the direct current electrolysis method proposed in the Patent No. 1001631 proposed by the present applicant, the alternating current electrolysis method proposed in the Patent Publication No. 2011-31121, or by using another well-known electrolysis method Colloidal solutions containing particles can be used.

As mentioned above, the present invention preferably contains metal nanoparticles having a uniform shape and a narrow particle distribution (uniform particles) of a desired size (less than 100 nm, preferably 20 nm or less), which is specific for an AC power source. It can be obtained by adjusting the concentration of the dispersant and the reducing agent in the frequency band according to the strength of the current of the alternating current power applied. Therefore, the colloidal solution containing the metal nanoparticles obtained by using the electrolysis method includes an electrolyte, a reducing agent and a dispersant introduced into the reaction vessel for the electrolysis process.

Thereafter, a centrifugal separation method may be used to remove an electrolyte, a reducing agent, and a dispersant unnecessary for ink preparation from the metal nanoparticle colloid solution (S12). When electrolysis is performed using a pair of silver (Ag) electrodes for a predetermined time, the electrolyte dissolved water contains a large number of silver nanoparticles in the dispersant, for example, in a centrifuge, for example, 4 hours, 8000 RPM. Conditioned centrifugation to remove the electrolyte, reducing agent and dispersant contained in the colloidal solution to obtain silver nanoparticles.

In this case, even if centrifugation is performed, the metal nanoparticles obtained are left in a state where the particle surface is capped with, for example, a water-soluble polymer dispersant or a water-dispersible polymer dispersant of a polyacryl, polyurethane, or polysiloxane system.

Subsequently, the metal nanoparticles obtained through centrifugation are dried at room temperature to 60 ° C. in a drying oven (S13), and after drying, the particles are agglomerated, and then ground using a mortar or the like (S14), or a stirrer such as a home mixer. Grind using. In addition, when drying the metal nanoparticles obtained through the centrifugation at room temperature, the grinding step using a mortar may be omitted.

Subsequently, after preparing the ink solvent and the auxiliary solvent for the bead mill input together with the pulverized metal nanoparticle powder to a stirrer such as a homomixer (S15), predispersion, that is, homomixing (simple stirring) (S16).

The pre-dispersion step is a process for making a bead mill sample, when the sample amount of the bead mill equipment is 1L, the amount of metal nanoparticles to be introduced is determined by the concentration of the final ink. For example, in the case of 40 wt% ink, 400 g of metal nanoparticles and 600 g of TGME (Triethylene Glycol Monomethyl Ether) solvent are mixed as an ink solvent and agitated at 7200 RPM for 4 h using a stirrer.

In this case, an auxiliary solvent may be added to the stirrer in addition to the ink solvent. The auxiliary solvent may be added to supplement the amount of the mixed metal nanoparticles and the ink solvent to be added to the bead mill if the sample amount to be added to the bead mill does not meet the prescribed amount.

In addition, the auxiliary solvent is a high concentration ink, that is, the content of the ink solvent mixed with the metal nanoparticles is small. In this case, when supplying the mixture to the stirrer or bead mill using the feed pump from the hopper is provided at the front end to the metal nanoparticles and the ink solvent is added for smooth transfer in the feed pump.

Moreover, in the case of high concentration inks, the metal nanoparticles may be added as washing solvents to clean the adherence to the bead mill equipment.

Therefore, when the mixed amount of the metal nanoparticles and the ink solvent is less than 1 L of the sample amount to be added to the bead mill, that is, the amount of the metal nanoparticles is not sufficient as 270 g, and the ink solvent TGME 320 g is used as an auxiliary solvent. To cover the lacking part (410g) with ethanol.

In addition, when the sample prescribed amount of the bead mill equipment in the pre-dispersion step is larger than 1L, the additional amount of the auxiliary solvent is determined correspondingly.

In addition, when preparing a high concentration ink of 100 cP or more that is not suitable for the bead mill process, a sample prepared by diluting with ethanol to a viscosity of 100 cP or less is prepared.

Subsequently, the sample in the colloidal state pre-dispersed using a bead mill is bead milled (S17). That is, the bead mill sample pre-dispersed through homo mixing (simple agitation) is put into the bead mill to disperse the metal nanoparticles and grind the nanoparticle powder at 500 to 6000 rpm for 1 to 10 hours.

In this case, three types of beads used for bead milling are used: 100, 50, and 30 μm, and the smaller the size of the beads, the better the ink having excellent dispersing force and jetting property.

In this case, it is preferable that the ratio of the mixing amount of the metal nanoparticles and the ink solvent and bead added to the bead mill is set to 3: 7. In addition, when the sample prescribed amount of the bead mill is 1L, the amount of beads to be put into the bead mill is 400 g is the most ideal bead amount, even if too large, the dispersibility is low, if the dispersibility is low, the resistivity is also low.

In the bead milling step, a precipitate is present when less than 1 hour, and agglomeration occurs when more than 10 hours, and an ink having the best jetting property is obtained when 6 hours.

In addition, if the rotor rotation speed of the bead mill is too fast exceeding 6000rpm, sufficient energy necessary for crushing cannot be given to the metal nanoparticles, so the dispersing force is lowered.If the rotor rotation speed of the bead mill is outside the range of 500 ~ 6000rpm, the size of the nanoparticles In addition, the dispersion becomes low and the resistivity increases accordingly.

The most preferable bead mill condition is 4000 RPM, 4 hours, in which case the dispersibility (size of nanoparticles) and the specific resistance are the lowest.

After the bead milling is completed, the auxiliary solvent is removed by fractional distillation when ethanol or the like is added as the auxiliary solvent in order to meet the sample prescribed amount of the bead mill equipment or to prepare a high viscosity ink (S18).

Therefore, the auxiliary solvent is required to have a boiling point lower than the boiling point of the ink solvent so that it can be removed by fractional distillation, and the auxiliary solvent is selected from the group consisting of ethanol, methanol, propanol, isopropanol, acetone, toluene and hexane. You can use one.

Accordingly, a fractional distillation process is performed only when ethanol is added in addition to the ink solvent. For example, 400 g of metal nanoparticles and 600 g of ink solvent (TGME) are used to prepare an ink having a metal nanoparticle content of 40 wt%. In this case, the ink can be prepared without a fractional distillation process.

As described above, after the ink is prepared, if nanoparticles or foreign substances or the like having a desired particle size or more are filtered as a post process (S19), a conductive metal nanoparticle ink is obtained (S20).

Hereinafter, a method of manufacturing a conductive metal nanoparticle ink according to a second embodiment of the present invention will be described with reference to FIG. 2.

Referring to FIG. 2, in the method of preparing a conductive metal nanoparticle ink according to the second embodiment of the present invention, preparing a colloidal solution containing metal nanoparticles (S21), an electrolyte of a metal nanoparticle colloidal solution after electrolysis , Removing through a centrifugation to remove the reducing agent and dispersant (S22), adding the centrifuged metal nanoparticles and the ink solvent to a bead mill with an auxiliary solvent (S23), to bead milling ( S24).

Thereafter, fractional distillation is carried out to remove the auxiliary solvent (S25), and as a general post-process, nanoparticles or foreign substances or the like having a desired particle size or more are filtered (S26), thereby obtaining a conductive metal nanoparticle ink (S27).

Compared with the first embodiment, the second embodiment first includes the step of drying and pulverizing the centrifuged metal nanoparticles because the centrifuged metal nanoparticles are directly introduced into a bead mill together with the ink solvent. I never do that.

In addition, the second embodiment includes a step of pre-dispersion, that is, homomixing (simple agitation) after the auxiliary solvent for the ink solvent and the bead mill is added to the homomixer with the pulverized metal nanoparticle powder I never do that.

If it is not necessary to meet the sample specification of the bead mill equipment, since the auxiliary solvent is not used, the process of removing the auxiliary solvent by fractional distillation can be omitted.

However, co-solvents may be used to meet the sample requirements of the bead mill equipment or to facilitate process, in which case the process includes removing the co-solvent by fractional distillation.

Therefore, in the preparation of the metal nanoparticle ink according to the second embodiment of the present invention, a colloidal solution containing metal nanoparticles is prepared through the electrolysis method described above, and an electrolyte, a reducing agent, and a dispersant of the prepared metal nanoparticle colloidal solution are prepared. The metal nanoparticles obtained by centrifugation are added directly to a bead mill with an ink solvent to perform bead milling, thereby obtaining ink in a simple process.

For example, when producing 40 wt% ink, 400 g of metal nanoparticles obtained by centrifugation and 600 g TGME solvent as the ink solvent are bead milled to obtain an ink.

Since other processes are the same as in the first embodiment, detailed description thereof will be omitted.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention by these examples.

<Samples 1 to 3>-Bead Mill Sample Preparation

First, a silver colloidal solution in which silver nanoparticles were dispersed using the alternating current electrolysis method proposed in Korean Patent Application Publication No. 2011-31121 was prepared. In the electrolyzed state, electrolytes, dispersants and reducing agents are dissolved in the silver colloidal solution. Especially, since the solution contains silver nanoparticles with an excess of dispersant, centrifugation is performed at 8000 RPM for 4 hours. The particles were obtained.

After washing by centrifugation, the rate of reduction of the dispersant is about 70 wt%. Silver nanoparticles obtained through centrifugation were dried in a 60 ℃ drying oven. After drying, the granular state is agglomerated, and then ground using a mortar to obtain powdered silver nanoparticles.

Pre-dispersion using Homer mixer is a process of making bead mill sample. Since the bead mill is based on 1 L sample, the amount of nanoparticles is determined by the concentration of final ink. In order to prepare 40wt% ink, 400g silver nanoparticles and 600g TGME solvent were mixed and then stirred for 7200 RPM for 4h using a homomixer.

In Table 1 below, the conditions of the homer mixing (predispersion) according to the concentration of the ink to be obtained are specified. In each case, homomixing is performed at 7200 RPM for 4 hours. It measured and the result is shown in Table 1.

Concentrated Homer Mixing Condition (1L Condition) for Bead Mill Sample Preparation silver
Nanoparticles (Solid) Ink solvent
Sol-1 Cosolvent
Sol-2 Reaction time RPM Particle diameter
(Mean, nm) density Sample 1 180 g TGME
(270 ml) EtOH
(550 ml) 4h 7200 259.2 40wt% Sample 2 180 g TGME
(180ml) EtOH
(640 ml) 4h 7200 151.2 50 wt% Sample 3 180 g TGME
(77 ml) EtOH
(743 ml) 4h 7200 181.7 70wt%

Diameter measurement of the nanoparticles in Table 1 was used for the DLS (Dynamic Light Scattering) method.

Referring to Table 1, the concentration of the ink shows a tendency to decrease the average diameter of the nanoparticles in proportion to the concentration up to 50wt%, but when the 70wt% shows an average diameter increases.

<Example 1, Comparative Examples 1 and 2> Ink Preparation and Viscosity Characteristics

Subsequently, an ink (Example 1) and an ink (Comparative Example 1 and Comparative Example 2), which were subjected to the bead mill process according to the present invention and agitated using a general stirrer instead of the bead mill process, were prepared, and then Viscosity was checked to determine the most important jetting properties.

In Example 1, the pre-dispersed sample according to Sample 1 (40 wt% ink) was added to 400 g of 100um zirconia beads into a bead mill, and after the bead mill process at 4000 RPM for 4 hours, fractional distillation was performed. Ink was prepared by removing ethanol.

Comparative Example 1 and Comparative Example 2, respectively, after pre-dispersed samples according to Sample 1 (40wt% ink) using a homomixer as a simple stirrer at a secondary dispersion process at 4000 RPM, 4 hours conditions, fractional distillation was performed. The ink was prepared by carrying out the ethanol removal.

The viscosity of the prepared ink, the residual amount of ethanol and water (EtOH, H ₂ O), Ag + dispersant, Ag (Solid) was measured and shown in Table 2. The Ag (Solid) was measured by thermogravimetric analysis (TGA).

ink EtOH, H ₂ O Ag + Dispersant Ag (Solid) Viscosity (room temperature) Example 1 3.040 wt% 36.13wt% 31.98wt% 24.4 Comparative Example 1 3.135wt% 46.34wt% 34.64wt% 39.0 Comparative Example 2 2.451wt% 44.57wt% 33.97wt% 31.8

As shown in Table 2, in Example 1, the residual amount of the dispersant adversely affecting the resistivity value in the ink was about 4.15 wt%, Comparative Example 1 was 11.7 wt%, and Comparative Example 2 was 10.6 wt%. It is expected that the ink of Example 1, which carried out the lower specific resistance than Comparative Examples 1 and 2, and the viscosity of the ink of Example 1, which performed the bead milling, was lower than that of Comparative Examples 1 and 2.

In addition, it is judged that the increase in viscosity in the inks of Comparative Examples 1 and 2 is due to the deterioration of the dispersibility of the nanoparticles.

<Residual Dispersant due to Temperature Change>

After ink jetting the substrate to form a conductive pattern, the temperature was increased to 500 ° C., followed by sintering. In FIG. 3, thermal decomposition showing the residual amount of ink with increasing temperature of the Ag nanoparticle ink to confirm the residual amount of the dispersant. The graph is shown.

As shown in FIG. 3, the sintering of the ink printed on the substrate was performed between 200 and 400 ° C. at which decomposition of the dispersant started. The residual amount of the dispersant may be obtained as a difference between the ink remaining amount at 200 ° C. and the ink remaining amount at 400 ° C.

Referring to the graph of Figure 3, the residual amount of the dispersant in the temperature range of 200 ~ 400 ℃ as in Example 1 (dotted dashed line) after the bead mill process after centrifugation in Comparative Example 1 (dotted line) and Comparative Example 2 (solid line) Appeared to be less.

As described above, since the dispersant remaining in the ink interferes with the conductive properties of the ink, the smaller the residual amount of the dispersant, the smaller the resistivity value of the ink.

Resistivity Characteristics

The resistivity values for Example 1, Comparative Example 1, and Comparative Example 2 were examined and shown in Table 3 below.

Ink type Sintering Temperature Sintering time Average resistivity
(μΩcm) Example 1 200 ℃ 1 hours 5.730848 Comparative Example 1 8.780903 Comparative Example 2 10.87321

As shown in Table 3, the specific resistance value also increased with the decrease in dispersion and the content of the dispersant. In addition, in the case of ink jetting, only the ink of Example 1 subjected to the bead mill was able to jet through the inkjet equipment.

<Examples 2 to 4>-Dispersibility Experiment

As shown in Table 4, for Sample 1, the ink was prepared by changing the RPM of the rotor, which is one of the amount of beads (using a bead of 100 μm) and bead mill conditions during bead milling.

That is, in the case of bead milling with respect to Sample 1, Example 2 used the beads 420g, rotor rotation RPM 3000, Example 3 used the beads 400g, rotor rotation RPM 3000, Example 4 used the beads 400 g, rotor rotation RPM was set to 4000 Ag nano particle size (Nano Particle Size) for the ink after the bead mill process was measured and the results are shown in the graph of FIG.

Referring to the graph of FIG. 4, it showed the best dispersibility when agitation was performed under the conditions of Example 4 (▲), in which the amount of the beads was set to 400 g and the rotor rotation RPM 4000. That is, Example 4, which was stirred at 4000 RPM for 4 hours using 400 g of 100 μm size beads, showed the smallest Ag nanoparticle (powder) having a size of about 20 nm, and the stirring time exceeded 4 hours. Even no further reduction in size occurred.

In addition, the specific resistance to the inks of Examples 2 to 4 obtained by changing the bead mill conditions and the recovery rate of the final ink were measured and shown in Table 4 below.

Bead amount (g) Rotor speed
(RPM) Resistivity
(μΩcm) Recovery
(%) density Example 2 (■) 420 3000 9.5 93 40wt% Example 3 (●) 400 3000 8.6 94.02 40wt% Example 4 (▲) 400 4000 5.7 85.82 40wt%

In addition, the dispersion of the ink obtained according to Example 4 is shown in Figure 5 the transmission (%) and reflectance (%) Backscattering (%) at room temperature using a Turbiscan equipment of Leanontech.

As shown in FIG. 5, it can be seen that the transmittance and reflectance along the X-axis (the height axis of the bottle containing the ink sample) of the graph appear constant without variation, and thus, it is determined that uniform dispersion is made.

The conductive ink obtained according to the present invention does not occur precipitation for 48 hours at room temperature, Turbiscan analysis showed that the dispersion stability for about 6 months or more.

By measuring the viscosity and the average surface tension of the ink obtained through the above-described examples for each concentration is shown in Table 5 below.

silver
Nanoparticle
(Solid) Ink solvent
Sol-1 Cosolvent
Sol-2 Viscosity
(cP range) Average surface tension
(dyne / cm ³ ) density Sample 4 Sample 1 prepared by dilution of ink 10.0 ~ 12.3 10wt% Sample 5 11.4 ~ 12.5 20wt% Sample 6 17.5 ~ 18.2 30wt% Sample 1 180 g TGME
(270 ml) EtOH
(550 ml) 26.8-31.2 33.124 40wt% Sample 2 180 g TGME
(180ml) EtOH
(640 ml) 49.5 ~ 55.2 31.873 50 wt% Sample 3 180 g TGME
(77 ml) EtOH
(743 ml) 5477 ~ 72585 57.25 70wt%

As shown in Table 5, in the present invention, it is possible to prepare a high concentration of ink of 10 to 70 wt%, the ink of the concentration of 10wt% to 30wt% can be prepared simply by diluting the ink of the concentration of 40wt%. . In addition, by diluting an ink having a concentration of 70 wt% in the same manner as an ink having a concentration of 10 wt% to 30 wt%, an ink having a concentration of 40 wt% and 50 wt% can also be easily produced.

It can be seen that the viscosity of the ink increases in proportion to the concentration of the ink. The ink having a concentration of 10 to 50 wt% according to the present invention is an industrial inkjet equipped with a SEMJET head (nozzle size: 30 pl) of Samsung Electro-Mechanics. The printer showed excellent jetting properties, and the ink having a concentration of 10 to 40wt% was well jetted even in an inkjet printer equipped with SEMJET head (nozzle size: 5pl) of Samsung Electro-Mechanics. In addition, the ink having a concentration of 70 to 90 wt% may not be jetted due to its high viscosity and may be applied for screen printing.

Example 5 Process 2 Example

In Example 5, the ink was prepared using the manufacturing process according to the second embodiment shown in FIG. 2 without undergoing a homer mixing process and the physical properties thereof were measured.

First, a silver colloidal solution in which silver nanoparticles were dispersed using the alternating current electrolysis method proposed in Korean Patent Application Publication No. 2011-31121 was prepared. In the electrolyzed state, electrolytes, dispersants and reducing agents are dissolved in the silver colloidal solution. Especially, since the solution contains silver nanoparticles with an excess of dispersant, centrifugation is performed at 8000 RPM for 4 hours. The particles were obtained.

Subsequently, after the centrifugation, the silver nanoparticles, which were not dried, were charged with 270 ml of TGME as an ink solvent and 550 ml of ethanol (EtOH) as an auxiliary solvent in a bead mill, as shown in Table 6 below. It was set to 4000 and bead milling was performed. Thereafter, fractional distillation was carried out in the same manner as in the above-described example to prepare a 40 wt% ink by removing ethanol.

Thereafter, the viscosity and average surface tension of the ink of Example 5 were measured and shown in Table 6 below.

silver
Nanoparticle
(Solid) Ink solvent
Sol-1 Cosolvent
Sol-2 Viscosity
(cP range) Average surface tension
(dyne / cm ³ ) density Example 5 180 g TGME
(270 ml) EtOH
(550 ml) 13.2 cp 34
dyne / cm ³ 40wt%

As shown in Table 6, it can be seen that the ink viscosity of Example 5 is the lowest as compared with the other examples of the same concentration, which indicates that the dispersion degree is excellent.

In the above-described embodiment, the conductive metal nanoparticle ink is manufactured by using silver nanoparticles as the metal nanoparticles, but it is of course possible to use other kinds of metal nanoparticles such as Cu which can be used for ink production.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to conductive metal nanoparticle inks and methods for their preparation, and in particular, to the production of conductive metal nanoparticle inks having excellent dispersibility, jetting properties, and low resistivity in an environmentally friendly and easy way using bead mill solution dispersion Can be applied.

Claims (21)

10 to 90% by weight of the metal nanoparticles obtained by electrolysis and 10 to 90% by weight of the ink solvent,
The metal nanoparticles are conductive metal nanoparticles ink, characterized in that the dispersant is capped. The method of claim 1,
The dispersant is a conductive metal nanoparticle ink, characterized in that containing 1 to 10% by weight based on the total ink. The conductive metal nanoparticle ink of claim 1, wherein the ink has a viscosity set in a range of 10.0 to 55.2 cP. The method of claim 2,
The dispersant capping the metal nanoparticles is a conductive metal nanoparticle ink, characterized in that the polyacrylic, polyurethane or polysiloxane-based water-soluble polymer dispersant or water dispersion polymer dispersant. The method of claim 1,
The metal nanoparticles are conductive metal nanoparticles ink, characterized in that any one or two or more alloys selected from the group consisting of Ag, Pt, Au, Mg, Al, Zn, Fe, Cu, Ni and Pd. The method of claim 1,
The ink solvent is conductive metal nanoparticle ink, characterized in that at least one selected from the group consisting of alcohols, glycols, alkyl-based, and cyclohexanone (Cyclohexanone). Removing the electrolyte and the dispersant from the metal nanoparticle colloidal solution obtained through electrolysis and separating the metal nanoparticles; And
And a bead mill step of uniformly dispersing and pulverizing the metal nanoparticles in the ink solvent by injecting the metal nanoparticles into the bead mill together with the ink solvent. The method of claim 7, wherein
The removal of the electrolyte and the dispersant from the metal nanoparticle colloidal solution is a method of producing a conductive metal nanoparticle ink, characterized in that using a centrifugation method. The method of claim 7, wherein
The conductive metal nano further comprising a pre-dispersion step for dispersing the aggregated metal nanoparticles with the ink solvent and the auxiliary solvent in the step of separating the electrolyte and dispersant from the metal nanoparticle colloid solution before the bead mill step Method for producing a particle ink. The method of claim 7, wherein
When the metal nanoparticles are added to the bead mill together with the ink solvent, if the mixed amount of the metal nanoparticles and the ink solvent to be added to the bead mill does not meet the sample prescribed amount to be added to the bead mill, it is supplemented or an auxiliary solvent for washing. Put them together,
And removing said auxiliary solvent by fractional distillation after said bead mill step. The method of claim 10,
The auxiliary solvent has a boiling point lower than the boiling point of the ink solvent to be removed by fractional distillation. The method of claim 10,
The amount of the auxiliary solvent is greater than (sample amount to be added to the bead mill-(mixing amount of metal nanoparticles and ink solvent)), and the conductive metal nanoparticle ink, characterized in that it is set to less than three times the sample amount. Manufacturing method. The method of claim 10,
The auxiliary solvent is at least one selected from the group consisting of ethanol, methanol, propanol, isopropanol, acetone, toluene and hexane. The method of claim 7, wherein the ink comprises 10 to 90 wt% of the metal nanoparticles and 10 to 90 wt% of the ink solvent. The method of claim 14, wherein the ink comprises 10 to 70 wt% of the metal nanoparticles and 30 to 90 wt% of the ink solvent. The method of claim 7, wherein the bead mill step is performed at 500 to 6000 rpm for 1 to 8 hours. The method of manufacturing a conductive metal nanoparticle ink according to claim 16, wherein the mixing ratio of the metal nanoparticles to the bead mill and the ink solvent and the beads are set to 3: 7. Centrifuging the colloidal solution in which the metal nanoparticles obtained by the electrolysis method are dispersed to remove the electrolyte and the dispersant, followed by drying to prepare the metal nanoparticles;
A predispersion step of preparing a mixed solution in which the metal nanoparticles are dispersed by mixing and stirring the dried metal nanoparticles with an ink solvent and an auxiliary solvent; And
Dispersing the mixed solution uniformly using a bead mill; Method for producing a conductive metal nanoparticle ink comprising a. 19. The method of claim 18, wherein the ink comprises 10 to 70% by weight of the metal nanoparticles and 30 to 90% by weight of the ink solvent. 19. The method of claim 18, wherein the metal nanoparticles are capped with a dispersant and comprise 1 to 10% by weight based on the entirety of the ink. 20. The method of claim 19, wherein the viscosity of the ink is set in the range of 10.0 to 55.2 cP.

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