WO2012099161A1 - 金属粒子粉末およびそれを用いたペースト組成物 - Google Patents
金属粒子粉末およびそれを用いたペースト組成物 Download PDFInfo
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- WO2012099161A1 WO2012099161A1 PCT/JP2012/050956 JP2012050956W WO2012099161A1 WO 2012099161 A1 WO2012099161 A1 WO 2012099161A1 JP 2012050956 W JP2012050956 W JP 2012050956W WO 2012099161 A1 WO2012099161 A1 WO 2012099161A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
- B22F1/054—Nanosized particles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
- B22F1/054—Nanosized particles
- B22F1/0545—Dispersions or suspensions of nanosized particles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
- B22F1/054—Nanosized particles
- B22F1/056—Submicron particles having a size above 100 nm up to 300 nm
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/102—Metallic powder coated with organic material
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C5/00—Alloys based on noble metals
- C22C5/06—Alloys based on silver
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
Definitions
- the present invention relates to fine metal particles (especially silver nanoparticles) suitably used for fine wiring, bonded bodies, and the like, and a paste containing the particles.
- metal nanoparticles have a specific surface area that is different from normal properties particularly as the particle size is reduced, and their use is expanding.
- fine particles there is a feature that they are highly reactive and easily melted, so that they are considered for use in applications such as conductive adhesives, bonding between substances, and formation of conductive wiring. I came.
- the present inventors have developed particles that are stable in the atmosphere while having a primary particle size of nano-order and suitable for mass production, and are disclosed in Patent Document 1 or 2.
- metal particles When metal particles are dispersed in a solvent to obtain a paste or ink, the surface properties of the metal particles greatly affect the properties of the ink.
- metal nanoparticles having a small average primary particle diameter have a large specific surface area, so the influence is remarkable. Therefore, it can be said that controlling the surface properties and ensuring the stability of the paste and the dispersibility of the particles are extremely important techniques.
- Patent Document 3 discloses a method for providing copper powder suitable for surface treatment with a fatty acid.
- powder pH JISK5101-17-2, etc.
- powder pH JISK5101-17-2, etc.
- Patent Documents 4 to 6 There are many examples of providing a paste.
- the size of the metal particles they provide ranges from nano to micron sizes.
- ink cannot be achieved by metal particles alone, and must be easily mixed with other materials constituting the ink.
- “easy to disperse in a polar solvent” means that it is separated from the polar solvent (dispersion medium) and does not aggregate and settle. If it separates and agglomerates and settles with respect to the dispersion medium, it cannot be said that the metal particles are present uniformly in the ink when the ink is used, and uniform wiring cannot be printed. .
- sample powder a powder of metal particles to be evaluated
- a solution obtained by mixing 100 mL of a potassium hydroxide solution having a pH 11 (blank solution) and 10 mL of ethyl alcohol.
- the present invention has been completed by finding that it can be solved by using a simple powder. That is, the metal particle powder based on the above index is easily dispersed in a polar solvent.
- the particle surface of the metal particles is a metal particle powder composed of an organic substance having a total carbon number of 8 or less.
- the metal particles have an average primary particle diameter of 10 to 1000 nm.
- a metal paste containing metal particles suitable for the application can be obtained.
- the pH value (reference pH value) indicated by the blank solution when 0.10 mol / L of nitric acid is added to 100 mL of a potassium hydroxide solution of pH 11 (blank solution) and the formula (1) are calculated. It is the figure which showed the correlation with the proton amount (number / m ⁇ 2 >) discharge
- metal particles are also simply referred to as “particles”, and are usually handled in a powder state, so they are also referred to as “metal particle powders” or simply “powder”.
- metal powder to be evaluated is referred to as “sample powder”.
- sample powder pulverized with 500 mesh contains 0.01 mol / L of potassium nitrate (wherein potassium nitrate is a buffer that suppresses a sudden increase in conductivity in the liquid accompanying an increase in ion concentration during titration)
- 0.10 mol / L nitric acid aqueous solution to this solution at a rate of 0.02 mL / min.
- the change in pH of the sample solution of the sample powder is measured.
- an aqueous potassium hydroxide solution or an alternative solution thereof has an action of absorbing carbonic acid in the air, it is not preferable to use a liquid that has passed several days after its production.
- the change in pH due to the addition of an aqueous nitric acid solution can be measured using, for example, a streaming potential automatic titrator (AT-510 Win / PCD-500 streaming potential automatic titrator manufactured by Kyoto Electronics Industry). Since it is preferable to perform measurement in a state where the dispersibility of the sample powder is maintained, it is preferable to perform pH measurement while stirring the solution using a magnetic stirrer.
- a streaming potential automatic titrator AT-510 Win / PCD-500 streaming potential automatic titrator manufactured by Kyoto Electronics Industry
- the pH The change is measured in advance and used as a standard for defining the pH change when the aqueous nitric acid solution is added to the sample powder dispersion.
- FIG. 1 shows a configuration diagram of a streaming potential automatic titration apparatus 1.
- the flow potential automatic titration measurement apparatus 1 includes a tank 2 that holds a potassium hydroxide solution, an electrometer (pH meter) 3 that measures pH, and a nitric acid aqueous solution titration apparatus 4.
- the tank 2 may be provided with a nitrogen gas introduction pipe 5 so that the pH does not change by absorbing carbon in the air. Further, the solution in the tank 2 was stirred by the magnetic stirrer 6 and the stirring bar 7.
- the magnetic stirrer 6 generates an alternating magnetic field 8 and rotates the magnetic stirring bar 7.
- the titration device 4 and the electrometer (pH meter) 3 of the present case are controlled by a control device (not shown), and the titration amount and the pH value are sequentially recorded.
- the pH change of the blank solution and the pH change of the solution containing the powder are obtained as shown in FIG. 2, for example.
- the white circle line 10 represents the pH change of the blank solution
- the black triangle line 11 represents the pH change of the solution containing the sample powder.
- the horizontal axis represents the total amount (ml) of the titrated nitric acid solution
- the vertical axis represents the pH value measured by the pH meter 3.
- the pH of the blank solution is set as “reference pH”
- the pH of the solution containing the sample powder is set as “indicated pH”
- the amount of protons (H + ) released or absorbed with respect to the metal particles can be calculated from the pH value measured based on the presence or absence of the sample powder. Specifically, it is calculated as follows. When the metal particles used as the sample powder release protons, the value of the proton amount takes a minus ( ⁇ ) value, and when it absorbs protons, it takes the value (+). In terms of pH value, when protons are released from the metal particles, pH takes an acidic side (smaller) value than the original reference, and takes a basic side (larger) value than the reference when absorbing protons.
- the amount of protons (H + ) per unit area released / absorbed (accumulated) in the liquid is calculated from the following equation (1).
- the pH value used in this calculation is the pH value when the same amount of nitric acid is added at the same concentration.
- the proton emission / absorption proton amount calculated by the equation (1) indicates how much protons are exchanged with the addition of powder in an environment where the same proton amount is added to the solution. Show. Therefore, it can be said that this value indicates the sensitivity of the powder to protons.
- the isoelectric point is a pH at which the surface charge of the powder is zero, and the electrophoretic mobility is zero at the isoelectric point.
- the isoacid point is a pH at which the pH does not change even when the powder is suspended in the solution. That is, the isoelectric point is a total view of the influence of all ions contained in the powder (basically on the surface), and the isoacid point is focused only on the exchange of protons by the powder.
- Teflon registered trademark
- the “dispersible metal particles (powder)” of the present invention refers to metal particles that maintain the form of primary particles when coated and have little aggregation between particles.
- evaluation is performed using a grind gauge method as described in “JISK-5600-2-5: 1999 General paint test method, Part 2: Properties and stability of paint—Section 5: Dispersion”. I can do it.
- the proportion of the muscle indicating that the particles are present in the portion of its diameter when minus the scraper as the evaluation of the aggregate points to be half of the total groove was evaluated as the average particle size D 50 .
- the paste used for this evaluation is, for example, 70 g of sample powder, 8.9 g of butyl carbitol acetate, 22.3 g of thermoplastic polyurethane resin (for example, Juliano 8001 manufactured by Arakawa Chemical Industries, Ltd.), 0.35 g of a polymer pigment dispersant ( For example, it is possible to evaluate a paste mixed with Ajimoto Fine Techno Co., Ltd. Ajisper PA-111) and kneaded with three rolls.
- the prepared paste its aggregation diameter (D 50 value) is 5.0 ⁇ m or less, preferably one as shown the following values 3.0 [mu] m.
- D 50 value its aggregation diameter
- an amount of nitric acid such that the pH value in the reference (blank solution) is 5 is charged into the potassium hydroxide solution containing the metal powder sample powder. Then, it was found that if the metal particles have surface characteristics such that the pH at that time is 6.0 or less, they are dispersed in a polar solvent and can be made into ink. In other words, this is a metal particle powder that is 3.0 ⁇ 10 19 (pieces / m 2 ) or less in terms of proton release.
- the copper particle of patent document 3 shows a value different from the value which this invention shows.
- the particles having surface properties as in the present invention have an average primary particle diameter of 10 to 1000 nm, preferably 20 to 500 nm, more preferably 30 to 300 nm, and still more preferably by a particle observation method using a TEM (transmission electron microscope).
- metal particles of 30 to 150 nm are a value determined for convenience according to the application, and fine particles can be further obtained by the method described in this specification.
- the upper limit of 1000 nm is exceeded, for example, low-temperature sinterability is hardly exhibited, which is not preferable.
- the particle diameter here may be calculated
- the average primary particle size at this time is preferably calculated from the result of measuring at least 200 particles.
- silver nanoparticles coated with an organic protective agent having a total carbon number of 8 or less are prepared by mixing a silver salt, an organic substance having a total carbon number of 8 or lower, and a reducing agent in water. (However, it is not excluded that the organic protective agent is replaced thereafter.)
- the second method is a method of synthesizing nanoparticles coated with a polymer substance that is easily detached, and then coating (substituting) with an organic protective agent having 8 or less carbon atoms according to the present invention.
- the first method is suitable for obtaining particles having an average primary particle size of 200 nm or less
- the second method is suitable for obtaining particles having an average primary particle size of 200 nm or more.
- organic protective agent having a double bond when used, particularly fine particles of 30 nm or less are obtained, such as a double bond or a carboxyl group.
- organic protective agent having a double bond in the structure (hereinafter referred to as “organic protective agent having a double bond”), it is easy to obtain fine particles of 30 nm or more.
- the organic substance having such an effect can be specifically a compound having a carbon-carbon double bond, a dihydroxyl compound, or a dicarboxyl compound among carboxylic acids.
- sorbic acid can be exemplified as a compound having a carbon-carbon double bond
- adipic acid can be exemplified as a dicarboxyl compound.
- the surface of the metal nanoparticle may be constituted by a compound having these structures.
- metal particles having an average primary particle diameter of 1 nm to 1000 nm are referred to as “nanoparticles” or “metal nanoparticles”.
- the metal is “silver”, it is also called “silver nanoparticles”.
- a polymer that is easily desorbed is temporarily coated, the polymer is replaced, and the organic material having a total carbon number of 8 or less is coated.
- the polymer used at this time is preferably an imine compound (polymer imine), and particularly preferably polyethylene imine.
- polymer imine one having a molecular weight of 300 or more can be preferably used.
- polymer imine one having a molecular weight of 300 or more can be preferably used.
- the surface of the metal particles is preferably covered with an organic substance having a total carbon number of 8 or less. Because it is covered with organic matter of this number of molecules, even when it is a fine powder having an average primary particle size of 100 nm or less, it is less likely to change even when stored in room temperature or in the atmosphere, and stable storage Particles with excellent properties can be obtained.
- the organic substance constituting the particle surface may be coated with a plurality of organic substances having different carbon numbers. If anything, coating with an organic substance having a single carbon number is preferred because the degree of dispersion in the solvent does not vary. Considering the stability of the particles, the number of carbon atoms constituting the organic substance is preferably 2 to 8, more preferably 3 to 7, and still more preferably 4 to 6.
- the particles covered with the organic substance as described above can be obtained as powder because they can exist stably in the atmosphere even when they are nanoparticles (deleted due to overlap).
- the particles having such a form are extremely easy to use compared to particles provided in a conventional cake form or dispersed liquid form.
- the handling is convenient, it is desirable to coat the surface of the particles prepared by the second method with an organic substance having a total carbon number of 8 or less.
- the particles once coated with the polymer imine can be obtained by adding a desired organic component (mainly carboxylic acid) having a total carbon number of 8 or less and replacing the particles. it can.
- ⁇ Production method of particles> Particle formation by the first method
- a preparation step for adjusting the aqueous metal solution and the reducing solution as a raw material, a heating step for increasing the temperature of the solution, and an aqueous metal solution as the raw material are used as the reducing solution.
- the liquid preparation step according to the first method includes a step of preparing a raw material aqueous solution (hereinafter referred to as a raw material solution) and a reducing solution.
- a raw material liquid a silver salt that is soluble in water, particularly preferably silver nitrate, is dissolved in pure water.
- the silver concentration at this time is 0.01 mol / L or more and 3.0 mol / L or less, preferably 0.01 mol / L or more and 2.0 mol / L or less, more preferably 0.01 mol / L or more and 1.0 mol / L or less.
- the concentration is too low, the reaction efficiency becomes too low, which is not preferable.
- the concentration is too high, the method of the present invention is not preferable because the reaction proceeds too much at one time and the particle size may become too uneven.
- the reducing solution is a mixture of water, aqueous ammonia, an organic substance covering the surface (particularly preferred is an organic acid) and a hydrazine hydrated aqueous solution.
- the reducing agent is equivalent to silver or more, preferably 2 equivalents or more to silver.
- the hydrazine hydrate may be any one that can reduce a metal as a reducing agent.
- a reducing agent other than hydrazine hydrate specifically, hydrazine, alkali borohydride (such as NaBH 4 ), lithium aluminum hydride (LiAlH 4 ), primary amine, secondary amine, tertiary amine, L-ascorbic acid, hydroquinone, gallic acid, formalin, phosphine, gluconic acid and derivatives thereof can also be used in combination.
- the amount of reducing agent added is preferably in the range of 0.5 to 9.0, preferably in the range of 0.5 to 8.0, more preferably in the range of 1.0 to 7.0, equivalent to the metal. If it is less than 0.5, unreduced metal may remain, such being undesirable. On the other hand, when it exceeds 9.0, the amount of the reducing agent increases, and the reaction may become excessively fast. For this reason, there is a possibility that the aggregated particles will increase and the particle size will eventually vary greatly.
- the ammonia water added to the reducing solution functions as a dissolution accelerator that dissolves organic substances having a total carbon number of 8 or less covering the surface, so that it is preferable to add from the viewpoint of improving work efficiency. That is, the organic matter is easily dissolved by adding ammonia water.
- the addition of aqueous ammonia is indispensable because the organic substance hardly dissolves without addition.
- the molar ratio of the surfactant that protects the surface of the metal nanoparticles to the metal component is 4.0 or less, preferably 0.1 to 3.0, more preferably, as the surfactant / metal component. May be in the range of 0.3 to 2.0.
- surroundings of silver is obtained. This indicates that there is a high possibility that many impurities remain in the finally produced silver composition, and it is difficult to obtain a high-purity silver film, which is not preferable.
- reaction process After the raw material liquid and the reducing liquid are stabilized at the set temperature, the raw material liquid is added to the reducing liquid and the reaction proceeds at once. At this time, it is preferable to proceed as uniformly as possible.
- the reaction may be made uniform by pressurization. In order to make the solution as uniform as possible during the reaction, high-speed stirring may be performed.
- “added all at once” as used herein refers to an embodiment in which the reaction factors such as the concentration, pH, and temperature of the reducing agent and protective agent do not substantially change depending on the addition timing of the aqueous silver nitrate solution. Further, the specific method is not particularly limited as long as the reaction factor does not substantially change depending on the addition timing of the aqueous silver nitrate solution.
- the obtained slurry is filtered or centrifuged to separate the product in the liquid from the mother liquor. Since the particles according to the present invention are obtained in the form of gently agglomerated, solid-liquid separation can be performed even by a conventionally known method such as filtration or a filter press when the scale is large.
- the obtained metal mass (silver mass) is set to a temperature condition of 100 ° C. or less, preferably 80 ° C. or less, more preferably 60 ° C. or less, and at least 0.5 hour or more, preferably 2 hours or more, more preferably 6 Let dry for more than an hour. At the time of drying, it can be dried in a drier kept at a constant temperature, but may be vacuum dried.
- the obtained metal powder coated with an organic substance was added to a solvent such as isopropyl alcohol and stirred, and then a treatment solution in which the organic substance to be replaced was dissolved was added. If it is stirred for about 6 hours, organic substances present on the surface can be replaced.
- the particles such as the coated metal powder according to the present invention can be easily replaced with the carboxylic acid that is the substance to be replaced. With such a configuration, a metal powder having desired surface properties or physical properties can be obtained.
- any of those used in the first method can be adopted, but it is particularly preferable to use a hydrazine solution. This is because hydrazine has been studied for various treatment methods, and a treatment method that meets the needs can be selected by appropriately selecting the type. In addition, at the time of adjustment of a reducing liquid, it is good to set it as 1 equivalent or more with respect to the silver amount which exists.
- the polymer imine compound since the polymer imine compound only needs to coexist at the time of reduction, it may be added to the silver raw material liquid before the reduction or may be added to the reducing liquid.
- the addition amount may be 0.1% by mass or more with respect to the mass of silver in the liquid.
- Silver nanoparticles having the surface coated with the polymer imine can be obtained by allowing the reducing agent to act in an environment in which the complex solution thus obtained coexists with the polymer imine described above.
- the addition rate of the reducing agent is preferably as fast as possible, and is preferably 1 equivalent / min or more. This indicates that, for example, when the reducing agent is set at a ratio of 1 equivalent to silver, the solution containing the reducing agent is added and mixed within 1 minute. At this time, from the viewpoint of advancing the reaction rapidly, stirring may be caused.
- the mixture After adding the substitute substance, the mixture is stirred for 10 minutes or more, the polymer imine covering the surface is replaced with a carboxylic acid having a total carbon number of 8 or less, and the average primary particle diameter is 200 nm or more coated with an organic substance having a total carbon number of 8 or less. Particles can be obtained.
- the silver nanoparticle slurry thus obtained can be subjected to known filtration and water washing (a filter press is used depending on the scale), followed by drying treatment to obtain a silver nanoparticle powder.
- the specific surface area of the metal particle powder according to the present invention measured by the BET method is 0.1 to 60 m 2 / g, more preferably 0.3 to 55 m 2 / g, and still more preferably 0.5 to 50 m 2 / g. If it is a metal particle which agree
- the conductive paste can be obtained by dispersing the above-mentioned silver nanoparticles in a dispersion medium.
- the dispersion medium used at this time is a polar solvent. By selecting a polar solvent, the vapor pressure is low, making it suitable for handling.
- thermosetting resins those having properties compatible with thermosetting resins may be used, but organic solvents such as esters, ethers, ketones, ether esters, alcohols, hydrocarbons, and amines are used. Is preferred.
- diols such as octanediol, alcohol, polyol, glycol ether, 1-methylpyrrolidinone, pyridine, terpineol, butyl carbitol, butyl carbitol acetate, texanol, phenoxypropanol, diethylene glycol monobutyl ether, diethylene glycol mono
- examples thereof include butyl ether acetate, ⁇ -butyrolactone, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, methoxybutyl acetate, methoxypropyl acetate, diethylene glycol monoethyl ether acetate, ethyl lactate, and 1-octanol.
- the conductive paste is generally used to form a circuit by printing, it is preferable to use a high boiling point solvent having low volatility during printing, and terpineol, butyl carbitol acetate, or octanediol is used. Is more preferable.
- a plurality of types of solvents may be used in combination.
- the amount of the solvent is preferably 30% by mass or less, more preferably 25% by mass or less, and most preferably 20% by mass or less based on the total amount of the thermosetting resin and the metal component.
- the metal particles of the present invention originally have surface properties that are dispersed in a polar solvent, but by using a dispersant, the independence of the silver nanoparticles can be ensured in the conductive paste.
- the property is not limited as long as it has an affinity for the surface of the silver nanoparticles and also has an affinity for the dispersion medium, and may be a commercially available one. Further, not only a single type but also a plurality of types may be used in combination.
- the amount at the time of addition is 6.0% by mass or less, preferably 3.0% by mass or less, more preferably 1.0% by mass or less, based on the addition weight of the silver nanoparticles.
- Dispersants having such properties include fatty acid salts (soap), ⁇ -sulfo fatty acid ester salts (MES), alkylbenzene sulfonates (ABS), linear alkylbenzene sulfonates (LAS), alkyl sulfates (AS), Low molecular weight anionic (anionic) compounds such as alkyl ether sulfate (AES) and alkyl sulfate triethanol, fatty acid ethanolamide, polyoxyethylene alkyl ether (AE), polyoxyethylene alkyl phenyl ether (APE), sorbitol, Low molecular weight nonionic compounds such as sorbitan, low molecular weight cationic (cationic) compounds such as alkyltrimethylammonium salt, dialkyldimethylammonium chloride, alkylpyridinium chloride, alkylcarboxyl Low molecular amphoteric compounds such as tine, sulfobetaine, lecithin,
- a conductive paste in addition to silver nanoparticle powder and a dispersion medium, it can be set as a resin-type paste by adding resin.
- the resin By adding the resin, it is possible to improve the shape maintenance property after printing and the adhesion to the substrate.
- the resin to be added any well-known thermosetting type or thermoplastic type resin can be adopted.
- the addition amount of the resin is 2 to 20% by mass, preferably 2 to 15% by mass, based on the total mass of the silver combined with the silver nanoparticles and the total mass of the resin. If the amount of the resin to be added is too large, the resin remains in the wiring more than necessary after firing, which is not preferable because it has a great influence on the conductivity. On the other hand, if the addition amount is reduced, the adhesion between the wiring and the substrate cannot be secured. Therefore, at least about 2% by mass is necessary for use as a resin-type (wiring) paste.
- thermoplastic resin any of the known thermoplastic resins can be used, and among them, it is preferable to add an acrylic resin, a polyester resin, or a polyurethane resin.
- acrylic resin a polyester resin
- polyurethane resin a polyurethane resin
- the polyurethane resin is not particularly limited as long as it is a commercially available thermoplastic urethane resin.
- examples thereof include a thermoplastic urethane resin obtained by polymerizing a polyol component and an organic polyisocyanate as essential components and using an optional component such as a chain extender or a terminator.
- hexamethylene diisocyanate HDI
- lysine isocyanate LI
- isophorone diisocyanate IPDI
- xylylene diisocyanate XDI
- H6-XDI hydrogenated XDI
- H12-MDI transcyclohexane 1,4-diisocyanate
- TMXDI tetramethylxylene diisocyanate
- TMXDI 1,6,11-undecane triisocyanate
- 1,8-diisocyanate-4-isocyanatomethyloctane 1,3,6-
- Examples include hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate (TMDI), and derivatives thereof.
- DI, IPDI, H6-XDI, H12-MDI are more preferred.
- polystyrene resin used together with the polyisocyanate
- a polyol having low crystallinity include polyethylene adipate (PEA), polybutylene adipate (PBA), polycarbonate (PCD), polytetramethylene glycol (PTMG), polycaprolactone polyester (PCL), polypropylene glycol (PPG) and the like.
- PEA polyethylene adipate
- PBA polybutylene adipate
- PCD polycarbonate
- PTMG polytetramethylene glycol
- PCL polycaprolactone polyester
- PPG polypropylene glycol
- the acrylic resin refers to a resin having a (meth) acrylic acid ester unit and / or a (meth) acrylic acid unit as a constituent unit. It may have a structural unit derived from a (meth) acrylic acid ester or a (meth) acrylic acid derivative.
- examples of the (meth) acrylate unit include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, (meth) T-butyl acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, (Meth) acrylic acid dicyclopentanyl, (meth) acrylic acid chloromethyl, (meth) acrylic acid 2-chloroethyl, (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 3-hydroxypropyl, (meth) Acrylic acid 2,3,4,5,6-pentahydroxyhexyl, (meth) acrylic acid 2,3,4, -
- examples of (meth) acrylic acid units include structural units derived from monomers such as acrylic acid, methacrylic acid, crotonic acid, 2- (hydroxymethyl) acrylic acid, and 2- (hydroxyethyl) acrylic acid. That means.
- polyester resin any conventionally known resin can be used.
- the production method is exemplified by a low molecular diol formed by condensation polymerization with a polycarboxylic acid or an ester-forming derivative thereof [an acid anhydride, a lower alkyl (carbon number 1 to 4) ester, an acid halide, etc.]
- a product obtained by ring-opening polymerization of a lactone monomer using a low molecular diol as an initiator can be used. Moreover, it does not prevent using these 2 or more types of mixtures.
- thermosetting resin any known thermosetting resin can be used.
- the thermosetting resin can be selected from phenol resin, epoxy resin, unsaturated polyester resin, isocyanate compound, melamine resin, urea resin, silicone resin, and the like.
- an epoxy resin and a phenol resin will be described.
- the epoxy resin according to the present invention has an effect of improving the weather resistance of the coating film.
- the epoxy resin either a monoepoxy compound, a polyvalent epoxy compound, or a mixture thereof is used.
- the monoepoxy compound include butyl glycidyl ether, hexyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether, para-tert-butylphenyl glycidyl ether, ethylene oxide, propylene oxide, paraxyl glycidyl ether, glycidyl acetate, glycidyl butyrate Glycidyl hexoate, glycidyl benzoate and the like.
- polyvalent epoxy compound examples include bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol AD, tetramethyl bisphenol S, tetrabromobisphenol A, and tetrachlorobisphenol A.
- Bisphenol-type epoxy resin obtained by glycidylation of bisphenols such as tetrafluorobisphenol A; epoxy resin obtained by glycidylation of other dihydric phenols such as biphenol, dihydroxynaphthalene and 9,9-bis (4-hydroxyphenyl) fluorene; 1,1,1-tris (4-hydroxyphenyl) methane, 4,4- (1- (4- (1- (4-hydroxyphenyl) -1-methylethyl) fe E) Ethylidene) Epoxy resins glycidylated with trisphenols such as bisphenol; Epoxy resins glycidylated with tetrakisphenols such as 1,1,2,2, -tetrakis (4-hydroxyphenyl) ethane; Phenol novolac, Cresol Novolak type epoxy resin obtained by glycidylation of novolak such as novolak, bisphenol A novolak, brominated phenol novolak, brominated bisphenol A
- a polyvalent epoxy compound is preferable from the viewpoint of enhancing storage stability.
- productivity is overwhelmingly high, so glycidyl-type epoxy resins are preferable, and more preferably epoxy obtained by glycidylation of polyhydric phenols because of excellent adhesion and heat resistance of cured products.
- Resins are preferred.
- a bisphenol type epoxy resin is more preferable, and an epoxy resin obtained by glycidylating bisphenol A and an epoxy resin obtained by glycidylating bisphenol F are particularly preferable.
- the resin is preferably in a liquid form.
- the epoxy equivalent is preferably 300 or less. When the epoxy equivalent is a value larger than 300, the composition becomes solid, the resistance value becomes high, and handling is inconvenient when used, which is not preferable.
- thermosetting phenol resin examples include liquid novolak type phenol resin, cresol novolac resin, dicyclopentadiene type phenol resin, terpene type phenol resin, triphenol methane type resin, phenol aralkyl resin and the like.
- ⁇ Other components that can be added> various additives for improving the stability and printability of the paste may be added.
- a leveling agent, a viscosity modifier, a rheology control agent, an antifoaming agent, an anti-sagging agent and the like can be mentioned.
- a conductive paste containing metal particles as a main component can be formed.
- Example 1 As an example of producing particles shown in Examples, an example of producing sorbic acid-coated silver nanoparticles will be described. In a 500 mL beaker, 13.4 g of silver nitrate (manufactured by Toyo Chemical Co., Ltd.) was dissolved in 72.1 g of pure water to prepare a silver solution.
- the obtained particles were confirmed to be silver nanoparticle powder having an average primary particle diameter of 60 nm according to an SEM image and a BET of 6.5 m 2 / g.
- the pH value indicated by pH was 4.96.
- the time-dependent change was confirmed by the change by the BET method in a normal temperature environment for half a year, it was confirmed that the change was less than 1% and no interparticle sintering occurred.
- the value of protons (H + ) released from the sample powder based on the above formula (1) was calculated to be 1.1 ⁇ 10 18 (pieces / m 2 ). Dispersibility evaluation is visually evaluated as ⁇ , and when the state of agglomerated powder by a grind gauge is confirmed, it is confirmed to be less than 5.0 ⁇ m, and when it is in an ink state, the powder has excellent dispersibility Was confirmed. The characteristics and the like are shown in Table 1.
- Example 2 The same operation as in Example 1 was repeated except that the reaction temperature was changed to 40 ° C., and the same evaluation as in Example 1 was performed.
- the obtained particles were confirmed to be silver nanoparticle powders having an average primary particle diameter of 100 nm and a BET of 4.4 m 2 / g according to an SEM image.
- Table 1 shows the evaluation results of physical properties and the like of the obtained substance.
- the time-dependent change was confirmed by the change by BET method for this powder in a 40 degreeC environment for half a year, it was confirmed that it was less than 1% change and the intergranular sintering did not arise.
- Example 3 25 g of the metal powder coated with sorbic acid obtained in Example 2 was added to Solmix (trade name of mixed alcohol) and stirred in a solvent while stirring at 25 ° C.
- covers the surface of a silver nanoparticle was replaced by the acetic acid from the sorbic acid by adding the processing liquid which added acetic acid 10g in Solmix 125 ml there. Whether or not the particle surface has been replaced is determined by GC-MS (Gas Chromatography-Mass Spectrometry: Gas Chromatograph-Mass Spectrometer). I have confirmed that.
- Table 1 shows the evaluation results of physical properties and the like of the obtained substance.
- the time-dependent change was confirmed by the change by BET method for this powder in a 40 degreeC environment for half a year, it was confirmed that it was less than 1% change and the intergranular sintering did not arise.
- Example 4 Substances to be substituted in Example 3 were octanoic acid (Example 4), malonic acid (Example 5), butanoic acid (Example 6), lactic acid (Example 7), propionic acid (Example 8), hexanoic acid.
- Example 9 was repeated except that oleic acid (Example 10) was used, and the operation of Example 3 was repeated, and the same evaluation as in Example 1 was performed.
- Table 1 shows the evaluation results of physical properties and the like of the obtained substance.
- the time-dependent change was confirmed by the change by BET method in a 40 degreeC environment for 6 months in these powders, it was confirmed that it was less than 1% change and the interparticle sintering did not arise.
- Example 11 As an example of producing 300 nm particles, an example of producing sorbic acid-coated silver nanoparticles will be described.
- a silver solution was prepared by dissolving 35.0 g of silver nitrate (manufactured by Toyo Chemical Co., Ltd.) and 0.04 g of copper nitrate dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) in 3700 g of pure water in a 5 L beaker.
- Table 1 shows the evaluation results of the physical properties of the obtained substance.
- time-dependent change was confirmed by the change by BET method in a 40 degreeC environment for 6 months in these powders, it was confirmed that it was less than 1% change and the interparticle sintering did not arise.
- ⁇ Comparative Example 1> 32.1 g of isobutyl alcohol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction medium and reducing agent, 55.3 g of oleylamine (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 267), silver nitrate crystals as a silver compound (Kanto Chemical) 6.89g was prepared, these were mixed, it stirred with the stirring blade connected to the motor, and silver nitrate was dissolved.
- isobutyl alcohol special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.
- silver nitrate crystals as a silver compound (Kanto Chemical) 6.89g was prepared, these were mixed, it stirred with the stirring blade connected to the motor, and silver nitrate was dissolved.
- the solution was transferred to a container equipped with a refluxer and placed on an oil bath, and the solution was stirred by a stirring blade connected to a motor while nitrogen gas was blown as an inert gas at a flow rate of 500 mL / min.
- the slurry was transferred to a decant tank that could remove the supernatant, and left for a whole day and night. Then, after removing the supernatant, the solution was transferred to a 500 mL beaker, 200 mL of methyl alcohol was added, and the mixture was stirred for 1 hour with a magnetic stirrer.
- the mixture was allowed to stand for 2 hours to precipitate the aggregates of silver nanoparticles coated with oleylamine, and the decantation again separated the washing liquid and the aggregates of silver nanoparticles. Such washing operation was repeated twice to complete the washing operation.
- the particles thus obtained were vacuum dried to remove the washing solvent, thereby obtaining metal nanoparticle powder coated with oleylamine.
- the obtained particles were confirmed to be silver nanoparticle powder having an average primary particle diameter of 10 nm according to a TEM image and a BET of 0.45 m 2 / g.
- the value of proton (H + ) released from the sample powder based on the above formula (1) was calculated to be 3.5 ⁇ 10 19 (pieces / m 2 ). Dispersibility evaluation is visually evaluated as x, and when the state of agglomerated powder by a grind gauge is confirmed, it is confirmed to be larger than 5.0 ⁇ m. It was confirmed that The characteristics and the like are shown in Table 1. In addition, although the time-dependent change was confirmed for this powder in a 40 degreeC environment over six months, it was confirmed that sintering has progressed to such an extent that it can be visually discerned.
- the horizontal axis is the reference pH value, and the vertical axis is the indicated pH value.
- the metal particles dispersed in the polar solvent according to the present invention have an indicated pH of 6.0 or less when the reference pH is 5.
- the indicated pH at the reference pH of 5 is obtained by interpolating the value at the time of pH] 5.0 from the measured values before and after the reference pH of 5.0.
- standard pH5.0 was shown with the dashed-two dotted line.
- grains calculated by Formula (1) is shown.
- the horizontal axis represents the value of the reference pH, and the vertical axis represents the amount of protons (number / m 2 ) determined by equation (1).
- the reference pH is 5
- the metal particles dispersed in the polar solvent of the present invention have a proton (H + ) released of 3.0 ⁇ 10 19 (number / m 2 ) or less (below the straight line 12).
- a metal particle powder excellent in redispersibility in a polar solvent, a paste using the metal particle-containing composition, and the like can be obtained, and therefore the fine silver nanoparticle-containing composition or dispersion is used. It can utilize suitably for each use.
- electrode formation for FPD / solar cell / organic EL, RFID wiring formation, wiring for embedding fine trenches, via hole contact holes, etc., coloring materials for painting cars and ships, medical care, diagnostics, biotechnology fields Carriers that absorb biochemical substances in the environment, antibacterial paints using antibacterial action, catalysts, conductive adhesives, conductive pastes mixed with resins, flexible printed circuits using them, highly flexible shields, capacitors, etc. Can be used for each purpose.
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Abstract
Description
500メッシュで解粒した試料粉末0.5gを、0.01モル/Lの硝酸カリウムを含む(ここで、硝酸カリウムは滴定時に生じるイオン濃度増加に伴う液中の導電性の急激な上昇を抑える緩衝剤として添加する)pH=11の水酸化カリウム溶液100mLとエチルアルコールを10mL混合した溶液に添加した後、この溶液に0.10モル/Lの硝酸水溶液を0.02mL/分の速度で添加して、試料粉末の試料溶液のpHの変化を測定する。ここで、水酸化カリウム水溶液もしくはその代替溶液は空気中の炭酸を吸収する作用があることから、作製してから数日以上経過した液を使用することは好ましくない。
(平均一次粒子径)
本発明のような表面性を有する粒子は特に、TEM(透過型電子顕微鏡)による粒子観察法による平均一次粒子径が10~1000nm、好ましくは20~500nm、一層好ましくは30~300nm、なお一層好ましくは30~150nmである金属粒子である。この粒子径の最小値はあくまで用途による便宜のために定めた値であり、本明細書に記載の方法によってはさらに微粒子を得ることもできる。一方、上限である1000nmを超えると、例えば低温焼結性が発現しにくくなるので好ましくない。なお、ここでいう粒子径はTEM写真の直接測定法で求めても良いし、画像処理で平均一次粒径を求めることもできる。この時の平均一次粒径は少なくとも200粒子を測定した結果から算出することが好ましい。また、粒子同士の重なり等が無い個々が独立した粒子で求め出すことが好ましい。
金属粒子表面は総炭素数8以下の有機物により表面が被覆されているのがよい。この程度の分子数の有機物で覆われていることにより、特に微細な100nm以下の平均一次粒子径を有するような粉末の場合でも、室温・大気中で保管しても変化を生じにくく、保管安定性に優れた粒子を得ることが出来る。
(第一の方法による粒子の形成)
具体的に、第一の方法により粒子を析出させる場合、原料である金属の水溶液及び還元液を調整する調液工程、溶液の温度を上昇させる昇温工程、原料である金属水溶液を還元液に添加し反応を行う反応工程、液中の金属粒子(特に銀ナノ粒子)を成長させる熟成工程、濾過・水洗・分散を繰り返し余分な有機物質を除去する洗浄工程、及び乾燥により液中の水分を除去する乾燥工程、また必要に応じて置換工程を付加した工程群によってなる。
第一の方法による調液工程は原料水溶液(以降、原料液という)と還元液を準備する工程からなる。原料液としては、水に溶解性のある銀塩、特に好ましくは硝酸銀を純水に溶解する。この時の銀濃度は、0.01mol/L以上3.0mol/L以下、好ましくは0.01mol/L以上2.0mol/L以下、一層好ましくは0.01mol/L以上1.0mol/L以下とする。あまりに濃度が薄すぎる場合には、反応効率が悪くなりすぎるので好ましくない。一方濃度が濃すぎる場合には、本発明の方法であれば反応が一度に進みすぎてしまい、粒子径が不均一になりすぎることがあるので好ましくない。
上記原料液、還元液を共に加熱して、おおよそ40~80℃にする。この時共に加熱するのは、後の工程で銀の還元反応を起こさせる際に、急激な温度差による事故を防止し、安全を確保するのに重要である。これは本反応は急激に進む反応であるので、出来る限り反応にばらつきが生じないよう注意を払う必要があるためである。なお、反応槽中の温度が前記温度範囲から外れると、40℃未満では、金属の過飽和度が上昇し、核発生が促進されるため、微粒が多くなりやすい。80℃超では、核発生は抑制されるが、粒子成長、粒子凝集が促進されやすい。
原料液および還元液が設定の温度で安定させた後、還元液に原料液を添加して反応を一度に進める。この時出来るだけ均一に進めることが好ましく、スケール(製造規模)によっては加圧して反応を均一にしても良い。なお、反応中には出来るだけ液を均一な状態とするために、高速攪拌を行っても良い。
反応液を混合した後、10~30分程度攪拌を続け、粒子の成長を完結させる。このときの反応は、サンプリングした反応液に対し、ヒドラジン水和物を滴下することにより、未還元銀の反応が生じるかどうか確認することによって、終点を判断する。
得られたスラリーについて濾過、あるいは遠心分離を行って、液中の生成物と母液を分離する。本発明に従う粒子は緩やかに凝集した形で得られるので、通常知られている濾過、あるいはスケールの大きな場合にはフィルタープレスといった方法であっても固液分離することが可能である。
得られた金属塊(銀塊)を、100℃以下、好ましくは80℃以下、一層好ましくは60℃以下の温度条件に設定し、少なくとも0.5時間以上、好ましくは2時間以上、一層好ましくは6時間以上乾燥させる。この乾燥時には定温に保持した乾燥機中に入れ乾燥することも出来るが、真空乾燥としても良い。
得られた有機物により被覆された金属粉末(被覆金属粉末)をイソプロピルアルコール等の溶媒に添加し攪拌したところに、置換する目的である有機物を溶解させた処理液を添加して、常温にて1~6時間程度攪拌すれば、表面に存在する有機物を置換することができる。ここで、本発明に従う被覆金属粉末のような粒子であれば、置換対象物質であるカルボン酸と容易に置換することが可能となる。このような構成とすることで、所望の表面性状あるいは物性を有するような金属粉末を得ることができるようになる。
第二の方法により粒子を得ようとする場合には、第一段階の高分子イミンにより被覆された銀ナノ粒子の形成する工程(この工程は、大別して原料の調液工程、反応工程からなる)と、第二段階として表面を被覆する高分子イミンを総炭素数8以下の有機物への置換する工程を経て形成させるという経路を通り形成させる。具体的には下記のようにして提供する。
硝酸銀をはじめとする原料成分を水溶液中に溶解し、アンモニア水あるいはアンモニウム塩を添加することで、銀のアンミン錯体を形成させる。銀に対するアンモニウム基の配位数は2であることから、ここでのアンモニウム添加量は銀に対して2当量以上とするのがよい。これを錯体溶液と呼ぶ。
こうして得られた錯体溶液と、上述の高分子イミンとが共存した環境下で還元剤を作用させることで高分子イミンが表面を被覆した銀ナノ粒子を得ることができる。還元剤(場合によっては高分子イミン化合物が共存している)の添加速度は可能な限り早いことが好ましく、1当量/分以上とするのがよい。これは、たとえば還元剤を銀に対して1当量比で設定した場合には、その還元剤が含まれる溶液を1分以内で添加混合することを示す。このとき反応を急速に進める観点から、攪拌を生じさせていても構わない。
反応は急速に進むので、反応後10分程度熟成させ反応を完結させた後、総炭素数8以下の有機物(主としてカルボン酸)を添加して、表面に形成された高分子イミンを置換する。なお、反応の完結の有無はたとえば、反応液の一部を抽出し、該溶液にベンシルを添加して反応が確認されるか否かで判断することができる。置換に用いる有機物は銀の存在量に対して0.02当量以上の添加を行えばよい。置換物質添加後は10分以上攪拌し、表面を被覆する高分子イミンを総炭素数8以下のカルボン酸の置換を行い、総炭素数8以下の有機物で被覆された平均一次粒子径200nm以上の粒子を得ることができる。
本発明に従う金属粒子粉末のBET法で測定した比表面積は0.1~60m2/g、より好ましくは0.3~55m2/g、一層好ましくは0.5~50m2/gである。この範囲に合致する金属粒子であれば、ペースト化する際の粘度調整が容易になるので好ましい。
導電性ペーストとしては、上述の銀ナノ粒子を分散媒に分散させることで得られる。この時に使用する分散媒は極性溶媒である。極性溶媒を選択することにより、蒸気圧が低く取扱に好適になる。
本発明にかかる導電性ペーストには銀ナノ粒子粉末をほどよく分散させる分散剤を添加しても良い。本発明の金属粒子はもともと極性溶媒中に分散する表面特性を有するが、さらに分散剤を使用することで、導電性ペースト中では銀ナノ粒子の独立性を確保することができる。その性質としては、銀ナノ粒子表面と親和性を有するとともに分散媒に対しても親和性を有するものであればよく、市販汎用のものであってもよい。また、単独の種類のみならず、複数種類を併用使用しても構わない。この添加する際の量は、銀ナノ粒子の添加重量に対して6.0質量%以下、好ましくは3.0質量%以下、一層好ましくは1.0質量%以下である。
本発明にかかる導電性ペーストとしては、銀ナノ粒子粉末および分散媒に加えて、樹脂を加えることで樹脂型ペーストとすることが出来る。樹脂を添加することで、印刷後の形状維持性や、基材との接着性を高めることができる。添加されるべき樹脂は、広く知られている熱硬化型もしくは熱可塑型のいずれの樹脂も採用することが出来る。樹脂の添加量としては、銀ナノ粒子を合わせた総銀質量と樹脂の合計質量に対して2~20質量%、好ましくは2~15質量%の添加量とするのがよい。添加をする樹脂量が多すぎると、焼成後に樹脂が必要以上に配線中に残ってしまい、導電性にも多大な影響を与えるため好ましくない。一方添加量を少なくすると配線と基板との密着性が確保できないため、樹脂型(配線)ペーストとして利用するには、少なくとも2質量%程度の添加は必要である。
本発明においては、知られている熱可塑性樹脂のいずれも使用することが出来るが、なかでも、アクリル樹脂やポリエステル樹脂やポリウレタン樹脂を添加するのが好ましい、一般的に知られているものとして、次のようなものが知られているが、上述の性質を有する場合には、本欄に記載のもの以外のものの使用を排除するものではない。
本発明においては、知られている熱硬化性樹脂のいずれも使用することが出来る。具体例としては、熱硬化性樹脂としては、フェノール樹脂、エポキシ樹脂、不飽和ポリエステル樹脂、イソシアネート化合物、メラミン樹脂、尿素樹脂、シリコーン樹脂などから選択することができる。ここでは、エポキシ樹脂とフェノール樹脂について説明する。
分散剤に加えて、ペーストの安定性や印刷性を改善するための各種添加剤を添加しても良い。例えば、レベリング剤、粘度調整剤、レオロジーコントロール剤、消泡剤、ダレ防止剤などがあげられる。以上のような構成により金属粒子を主構成成分とする導電性ペーストを形成することが出来る。
実施例に示す粒子の作製例として、ソルビン酸被覆の銀ナノ粒子を製造する例について示す。500mLビーカーへ硝酸銀(東洋化学株式会社製)13.4gを純水72.1gへ溶解させ、銀溶液を作製した。
反応温度を40℃に変更した以外は実施例1と同様の操作を繰り返し、かつ実施例1と同様の評価を行った。得られた粒子は、SEM像による平均一次粒子径が100nmであり、BETが4.4m2/gの銀ナノ粒子粉末であることが確認された。得られた物質の物性等の評価結果を表1に示す。なお、この粉末を半年にわたって40℃環境下で経時変化をBET法による変化で確認したが1%未満の変化にとどまり、粒子間焼結が生じていないことが確認された。
実施例2により得られたソルビン酸で被覆された金属粉末25gをソルミックス(混合アルコールの商品名)中に添加し、25℃で攪拌しながら溶媒中でかき混ぜた。そこに、酢酸10gをソルミックス125ml中に加えている処理液を添加することで、銀ナノ粒子の表面を被覆する有機物をソルビン酸から酢酸に置換した。なお、粒子表面の置換ができているか否かについてはGC-MS(Gas Chromatgragh-Mass Spectrometry:ガスクロマトグラフ-質量分析計)を用いて、加熱によりガスを捕集し表面を構成する成分が交換されていることは確認している。得られた物質の物性等の評価結果を表1に示す。なお、この粉末を半年にわたって40℃環境下で経時変化をBET法による変化で確認したが1%未満の変化にとどまり、粒子間焼結が生じていないことが確認された。
実施例3において置換する物質を、オクタン酸(実施例4)、マロン酸(実施例5)、ブタン酸(実施例6)、乳酸(実施例7)、プロピオン酸(実施例8)、ヘキサン酸(実施例9)、オレイン酸(実施例10)とした以外は同様にして、実施例3の操作を繰り返し、かつ実施例1と同様の評価を行った。得られた物質の物性等の評価結果を表1に示す。なお、これらの粉末を半年にわたって40℃環境下で経時変化をBET法による変化で確認したが1%未満の変化にとどまり、粒子間焼結が生じていないことが確認された。
300nm粒子の作製例として、ソルビン酸被覆の銀ナノ粒子を製造する例について示す。5Lビーカーへ硝酸銀(東洋化学株式会社製)35.0gと硝酸銅二水和物(和光純薬工業株式会社製)0.04gを純水3700gへ溶解させ、銀溶液を作製した。
反応媒体兼還元剤としてイソブチルアルコール(和光純薬工業株式会社製特級試薬)32.1g、オレイルアミン(和光純薬工業株式会社製、分子量=267)55.3g、銀化合物としての硝酸銀結晶(関東化学株式会社製) 6.89gを用意し、これらを混合してモーターに接続された攪拌羽根にて攪拌し、硝酸銀を溶解させた。この溶液を還流器のついた容器に移してオイルバスに載せ、容器内に不活性ガスとして窒素ガスを500mL/minの流量で吹込みながら、該溶液をモーターに接続された攪拌羽根により攪拌しながら110℃まで昇温した。110℃の温度で5時間の還流を行なった後、還元補助剤として2級アミンのジエタノールアミン(和光純薬工業株式会社製、分子量=106)を4.30g添加した。その状態で1時間保持した後、反応を終了した。
2 タンク
3 pH計
4 硝酸水溶液の滴定装置
5 窒素ガスの導入管
6 マグネチックスターラー
7 撹拌子
8 交流磁界
Claims (6)
- pH=11の水酸化カリウム溶液100mL(ブランク溶液)とエチルアルコールを10mL混合した溶液に、0.5gの評価すべき金属粉末を加えてから、0.10mol/Lの硝酸を添加してpH=5となる量の硝酸量を0.10mol/Lの硝酸を加えたときに指示されるpH値が6.0以下を示す金属粒子粉末。
- pH=11の水酸化カリウム溶液100mL(ブランク溶液)とエチルアルコールを10mL混合した溶液に、0.10mol/Lの硝酸を添加して、pHが4.5~5.0となる量の硝酸量を、pH=11の水酸化カリウム溶液100mLに0.5gの試料粉末を加えたものに添加した際に算出される評価すべき金属粒子から放出されるプロトン(H+)が3.0×1019(個/m2)以下である、金属粒子粉末。
- 粒子表面が総炭素数8以下の有機物で構成されている、請求項1または2に記載の金属粒子粉末。
- 前記金属粒子粉末は大気中40℃で保持しても粒子間焼結を生じない性質を有する、請求項1ないし3のいずれかに記載の金属粒子粉末。
- 請求項1ないし4のいずれかに記載の金属粒子粉末と分散溶媒を含む、金属ペースト。
- 請求項1ないし4のいずれかに記載の金属粒子粉末と分散溶媒および少なくとも一種の樹脂を含む、導電性ペースト。
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EP12736277.0A EP2666565A1 (en) | 2011-01-18 | 2012-01-18 | Metal particle powder and paste composition using same |
KR1020137021500A KR20140052938A (ko) | 2011-01-18 | 2012-01-18 | 금속 입자 분말 및 그것을 이용한 페이스트 조성물 |
CN201280005642XA CN103328135A (zh) | 2011-01-18 | 2012-01-18 | 金属粒子粉末及使用该粉末的糊料组合物 |
US13/977,806 US20130270488A1 (en) | 2011-01-18 | 2012-01-18 | Metal particle powder and paste composition using same |
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JP2015197304A (ja) * | 2014-03-31 | 2015-11-09 | 住友金属鉱山株式会社 | 金属粉末表面の評価方法 |
JP2021004852A (ja) * | 2019-06-27 | 2021-01-14 | 住友金属鉱山株式会社 | 導電性ペーストの粘度の経時安定性の評価方法 |
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JP6174301B2 (ja) * | 2011-03-28 | 2017-08-02 | Dowaエレクトロニクス株式会社 | 銀粉および導電性ペースト |
JP6049606B2 (ja) * | 2013-12-25 | 2016-12-21 | 株式会社ノリタケカンパニーリミテド | 加熱硬化型導電性ペースト |
KR102397620B1 (ko) * | 2015-02-19 | 2022-05-16 | 주식회사 다이셀 | 은 입자 도료 조성물 |
CN105252014A (zh) * | 2015-10-30 | 2016-01-20 | 上海纳米技术及应用国家工程研究中心有限公司 | 一种碱性体系中制备超细银粉的方法 |
CN105834449B (zh) * | 2016-05-04 | 2017-09-22 | 苏州思美特表面材料科技有限公司 | 一种利用微纳米气泡作为晶种诱导生产银粉的制备方法 |
TWI623946B (zh) * | 2016-07-05 | 2018-05-11 | 國立成功大學 | 奈米銀漿料之製備方法 |
CN112371993B (zh) * | 2020-10-16 | 2022-12-20 | 湖南中伟新银材料科技有限公司 | 一种银粉的制备方法 |
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US20130270488A1 (en) | 2013-10-17 |
JPWO2012099161A1 (ja) | 2014-06-30 |
CN103328135A (zh) | 2013-09-25 |
EP2666565A1 (en) | 2013-11-27 |
KR20140052938A (ko) | 2014-05-07 |
TW201235130A (en) | 2012-09-01 |
TW201231191A (en) | 2012-08-01 |
WO2012098643A1 (ja) | 2012-07-26 |
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