WO2012173171A1 - Coated fibrous copper microparticles, and electrically conductive coating agent and electrically conductive film each containing said coated fibrous copper microparticles - Google Patents

Coated fibrous copper microparticles, and electrically conductive coating agent and electrically conductive film each containing said coated fibrous copper microparticles Download PDF

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Publication number
WO2012173171A1
WO2012173171A1 PCT/JP2012/065187 JP2012065187W WO2012173171A1 WO 2012173171 A1 WO2012173171 A1 WO 2012173171A1 JP 2012065187 W JP2012065187 W JP 2012065187W WO 2012173171 A1 WO2012173171 A1 WO 2012173171A1
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Prior art keywords
fine particles
copper fine
fibrous copper
fibrous
coated
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PCT/JP2012/065187
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French (fr)
Japanese (ja)
Inventor
山田　宗紀
朗 繁田
雅弘 細田
良彰 越後
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ユニチカ株式会社
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Priority to JP2013520573A priority Critical patent/JP6076249B2/en
Priority to KR1020137027406A priority patent/KR20140020286A/en
Priority to US14/123,632 priority patent/US20140120360A1/en
Priority to CN201280024258.4A priority patent/CN103547396B/en
Publication of WO2012173171A1 publication Critical patent/WO2012173171A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • 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
    • 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
    • B22F1/06—Metallic powder characterised by the shape of the particles
    • B22F1/062—Fibrous particles
    • 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
    • B22F1/17—Metallic particles coated with metal
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/24—Electrically-conducting paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • C09D7/62—Additives non-macromolecular inorganic modified by treatment with other compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/66—Additives characterised by particle size
    • C09D7/69—Particle size larger than 1000 nm
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/70—Additives characterised by shape, e.g. fibres, flakes or microspheres
    • 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
    • H01B1/026—Alloys based on copper
    • 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
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12014—All metal or with adjacent metals having metal particles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12181—Composite powder [e.g., coated, etc.]

Definitions

  • the present invention relates to coated fibrous copper fine particles, and a conductive coating agent and a conductive film containing the coated fibrous copper fine particles.
  • Spherical copper fine particles are widely used as raw materials for conductive coating agents and the like because they are excellent in conductivity and inexpensive.
  • Such conductive coating agents are widely used in materials for forming circuits using various printing methods on printed wiring boards and the like, various electrical contact members, and the like.
  • transparent conductive material transparent conductive material
  • transparent conductive film for example, applications such as touch panels and flat panel displays
  • spherical copper fine particles as a conductive material in a transparent conductive material such as a conductive coating agent or a conductive film.
  • the performance which can form a conductive film is requested
  • the conductive coating agent containing spherical copper fine particles coated with conventional silver as described above is applied as a coating material for forming a conductive layer of a transparent conductive film used for a touch panel, for example.
  • the content of the spherical copper fine particles coated with silver is increased, the transparency in the conductive layer is lowered.
  • the content of the copper fine particles coated with silver is reduced in order to ensure transparency, there is a problem that the conductivity in the conductive layer is lowered. That is, in the conventionally known transparent conductive material containing spherical copper fine particles coated with a noble metal such as silver, any one of conductivity and transparency required for the conductive layer of the transparent conductive film is used. Is difficult to satisfy.
  • an object of the present invention is to solve the above-mentioned problems, and to provide coated fibrous copper fine particles that are excellent in both conductivity and transparency when contained in a transparent conductive material.
  • the present inventors have found that metal other than copper, such as silver, with respect to fibrous copper fine particles formed from copper, which is a metal that is significantly less expensive than silver. It was found for the first time that the coated fibrous copper fine particles formed by coating can be a conductive material excellent in both conductivity and transparency when contained in a transparent conductive material, and the present invention has been completed.
  • the present invention has the following purpose.
  • Coated fibrous copper fine particles characterized by being.
  • the minor axis of the fibrous copper fine particles is 1 ⁇ m or less, and the proportion of the copper particles having a minor axis of 0.3 ⁇ m or more and an aspect ratio of 1.5 or less in the fibrous copper fine particles is fibrous copper.
  • a conductive coating agent comprising the coated fibrous copper fine particles of (1) or (2).
  • a conductive film comprising the coated fibrous copper fine particles of (1) or (2).
  • the coated fibrous copper fine particles of the present invention are coated fibrous copper fine particles in which at least a part of the surface of the fibrous copper fine particles is coated with a metal other than copper, and the length of the fibrous copper fine particles is 1 ⁇ m or more. And has a specific shape and configuration with an aspect ratio of 10 or more. Therefore, by using such coated fibrous copper fine particles, it is possible to obtain a conductive coating agent, a conductive film and a conductive film having both excellent conductivity and transparency.
  • coated fibrous copper fine particles of the present invention are coated fibrous copper fine particles in which at least a part of the surface of the fibrous copper fine particles is coated with a metal other than copper, and the length of the fibrous copper fine particles is 1 ⁇ m or more. Yes, and the aspect ratio is 10 or more.
  • the coated fibrous copper fine particles of the present invention are obtained by coating the surface of the fibrous copper fine particles with a metal other than copper. As shown in FIG. The shape is maintained. Fibrous copper fine particles coated with a metal other than copper are superior in stability in a solvent or in the air as compared with uncoated fibrous copper fine particles.
  • metals other than copper for coating the fibrous copper fine particles include noble metal elements (gold, platinum, silver, palladium, rhodium, iridium, ruthenium, osmium, etc.) and base metal elements (iron, cobalt, tin, etc.). It is done. These may be used alone or in combination of two or more. Among these, at least silver is preferably used from the viewpoints of conductivity and stability.
  • the method for coating uncoated fibrous copper fine particles with a metal other than copper, such as silver is not particularly limited, but an electroless plating method is preferably used.
  • an electroless plating method for example, when silver is coated, silver nitrate, ammonium carbonate or ethylenediaminetetraacetate silver
  • a method of depositing a silver coating on the surface of the fibrous copper particles can be used.
  • the fibrous copper fine particles not coated with metal (that is, uncoated) will be described.
  • the length of the fibrous copper fine particles needs to be 1 ⁇ m or more, preferably 5 ⁇ m or more, and more preferably 10 ⁇ m or more.
  • the length of the fibrous copper fine particles is less than 1 ⁇ m, it is difficult to achieve both good conductivity and transparency in the transparent conductive material containing the coated fibrous copper fine particles of the present invention.
  • it may be preferable that the length of the fibrous fine particles does not exceed 500 ⁇ m from the viewpoint of handling the coating agent when forming the conductive film or conductive film containing the coated fibrous copper fine particles of the present invention. .
  • the minor axis of the fibrous copper fine particles is preferably 1 ⁇ m or less, more preferably 0.5 ⁇ m or less, further preferably 0.2 ⁇ m or less, and particularly preferably 0.1 ⁇ m or less. If the short diameter of the fibrous copper fine particles exceeds 1 ⁇ m, the transparent conductive material containing the coated fibrous copper fine particles of the present invention may be inferior in transparency.
  • the aspect ratio of the fibrous copper fine particles (the length of the fibrous body / the short diameter of the fibrous body) needs to be 10 or more, preferably 100 or more, and more preferably 300 or more. .
  • the aspect ratio of the fibrous copper fine particles is less than 10 (that is, close to spherical)
  • the transparent conductive material containing the coated fibrous copper fine particles of the present invention achieves both transparency and conductivity. It becomes difficult.
  • the entire surface is coated with a metal other than copper, but there is a portion where copper is not exposed and is not coated with metal. Also good.
  • the content of the coating metal other than copper in the coated fibrous copper fine particles is preferably 1 to 50% by mass, more preferably 10 to 50% by mass, and more preferably 15 to 30% with respect to the total mass of the coated fibrous copper fine particles. More preferred is mass%. If the content is less than 1% by mass, the improvement in conductivity, which is an effect produced by coating the metal, may be insufficient.
  • the metal coating amount can be obtained, for example, by dissolving the coated fibrous copper fine particles of the present invention in a strong acid to obtain a measurement solution, and measuring this solution by ICP (high frequency inductively coupled plasma). I can do it.
  • the method for obtaining the short diameter and length (major diameter) of the fibrous copper fine particles and the copper particles described later, and the method for calculating the number of copper particles per fibrous copper fine particle are as follows. It is. That is, an aggregate of fibrous copper fine particles is observed using a transmission electron microscope (TEM), a scanning electron microscope (SEM), or the like. For example, a digital microscope (manufactured by Keyence Corporation, “VHX-1000, VHX-D500 / 510”) or the like can be used for observing the fibrous copper fine particles.
  • 100 fibrous copper fine particles are selected from the aggregate.
  • the short diameter and the length of the fibrous copper fine particles and the copper particles adhering to or in contact with the fibrous copper fine particles are measured, and the average value of these can be used as the short diameter and the length.
  • the aspect ratio of the fibrous copper fine particles and the copper particulates can be calculated by dividing the length obtained as described above by the minor axis. Further, by counting the number of copper particles present and dividing the number of copper particles by the number of fibrous copper particles (100), the number of copper particles per fibrous copper particle is calculated. can do.
  • the fibrous copper fine particles of the present invention when observing the fibrous copper fine particles of the present invention, if the fibrous copper fine particles overlap and are densely packed, the shapes of the fibrous copper fine particles and the copper particulates may not be accurately evaluated. . Therefore, in such a case, the fibrous copper fine particles that are densely packed until the adjacent fibrous copper fine particles are not in close contact with each other can be solved by using an ultrasonic dispersion device or the like.
  • the proportion of copper particles having a minor axis of 0.3 ⁇ m or more and an aspect ratio of 1.5 or less is 0.1 or less per fibrous copper fine particle.
  • the number is preferably 0.08 or less, more preferably 0.05 or less, and most preferably none.
  • the transparent conductive material containing the coated fibrous copper fine particle of the present invention may be inferior in transparency.
  • the minor axis of the copper granule that affects the transparency is 0.3 ⁇ m or more, and the aspect ratio (the length of the copper granule / the minor axis of the copper granule) is 1.5 or less.
  • the following method is used. That is, a method of depositing fibrous copper fine particles from an aqueous solution containing a copper ion, an alkaline compound, a nitrogen-containing compound capable of forming a stable complex with copper ion, and a reducing compound is used. At this time, it is preferable to use a reducing compound that does not react with dissolved oxygen in the alkaline aqueous solution.
  • the presence ratio of copper particulates exceeds 0.1 per one fibrous copper fine particle. In other words, only fibrous copper fine particles having a large number of copper particles may be obtained.
  • the “reducing compound that does not react with dissolved oxygen” is defined by the following index.
  • the dissolved oxygen concentration 1 is 8.3 mg / L.
  • a dissolved oxygen meter “DO-5509” manufactured by Lutron
  • a reducing compound is added to the alkaline aqueous solution so as to have a concentration of 0.50 mol / L.
  • a magnetic stirrer so that the aqueous solution does not vortex and dissolve.
  • the dissolved oxygen concentration in the aqueous solution is measured 0.5 minutes, 5 minutes, 10 minutes, 15 minutes and 30 minutes after the addition of the reducing compound while continuing stirring after dissolution.
  • the dissolved oxygen concentration 10 minutes after the addition of the reducing compound is defined as “dissolved oxygen concentration 2”.
  • A (Dissolved oxygen concentration 2) / (Dissolved oxygen concentration 1) (1)
  • a reducing compound having a numerical value A of 0.5 or more obtained by the formula (1) is defined as “a reducing compound that does not react with dissolved oxygen”.
  • the reducing compound whose numerical value A is less than 0.5 is defined as "the reducing compound which reacts with dissolved oxygen”.
  • Examples of the reducing compound that does not react with dissolved oxygen include ascorbic acid, erythorbic acid, glucose, or hydroxylammonium salt.
  • the numerical value A of these reducing compounds that do not react with dissolved oxygen is 0.5 or more.
  • the copper fine particles are generally precipitated by using hydrazine as a reducing compound contained in the reaction solution.
  • a “reducing compound that reacts with dissolved oxygen” such as hydrazine
  • only fibrous copper fine particles with an increased proportion of copper particles may be obtained.
  • the fibrous copper fine particles themselves cannot be deposited.
  • the numerical value A obtained by the above formula (1) is about 0.05.
  • the water contained in the aqueous solution is preferably one having a dissolved oxygen concentration of 1 mg / L or more, and more preferably 3 mg / L or more.
  • the ratio of copper particles per fibrous copper fine particle exceeds 0.1, and as a result contained in a transparent conductive material or the like. In some cases, only fibrous copper fine particles having poor transparency can be obtained.
  • the reducing compound as described above is preferably used in a proportion of 0.5 to 5.0 molar equivalents relative to copper ions in the aqueous solution, and is preferably used in a proportion of 0.75 to 3.0 molar equivalents. More preferred. When used in a proportion of less than 0.5 molar equivalent, the formation efficiency of the fibrous copper fine particles may be lowered. On the other hand, even if it exceeds 5.0 molar equivalent, the formation effect of the fibrous copper fine particles is saturated, which is not preferable from the viewpoint of cost.
  • Copper ions can be generated by dissolving a water-soluble copper salt in water.
  • the water-soluble copper salt include copper sulfate, copper nitrate, copper chloride, and copper acetate.
  • copper sulfate or copper nitrate can be preferably used from the viewpoint of easy formation of the fibrous copper fine particles of the present invention.
  • the alkaline compound is not particularly limited, and sodium hydroxide, potassium hydroxide and the like can be used.
  • the concentration of the alkaline compound in the aqueous solution is preferably 15 to 50% by mass, more preferably 30 to 50% by mass, and further preferably 35 to 45% by mass.
  • concentration of the alkaline compound is less than 15% by mass, it may be difficult to form the fibrous copper fine particles of the present invention.
  • concentration exceeds 50% by mass, it may be difficult to handle the aqueous solution.
  • the concentration of copper ions in the aqueous solution is defined by the molar ratio of hydroxide ions and copper ions of the alkaline compound. That is, (hydroxide ion of alkaline compound) / (copper ion) is preferably set to have a molar ratio of 3000/1 to 6000/1, preferably 3000/1 to 5000/1. More preferably, the range is set.
  • the molar ratio is less than 3000/1, the formation of the copper particles cannot be suppressed, and as a result, the existence ratio of the copper particles exceeds 0.1 per one fibrous copper fine particle.
  • the shape of the copper fine particles may not be fibrous but spherical.
  • the molar ratio exceeds 6000/1 the formation efficiency of the fibrous copper fine particles may deteriorate.
  • Examples of the nitrogen-containing compound that forms a stable complex with a divalent copper ion in an aqueous solution include ammonia, ethylenediamine, or triethylenetetramine.
  • ethylenediamine can be preferably used from the viewpoint of easy formation of fibrous copper fine particles.
  • said nitrogen-containing compound is used in the ratio of 1 mol or more with respect to 1 mol of copper ions from a viewpoint of the formation efficiency of fibrous copper microparticles.
  • the aqueous solution containing the above-described components is heated with an appropriate heat source, and then the heating of the aqueous solution is continued, or the liquid temperature of the aqueous solution is lowered to precipitate the desired fibrous copper fine particles.
  • the latter method that is, a method of lowering the liquid temperature after heating is more preferable.
  • the heating temperature of the aqueous solution is not particularly limited, but is preferably 50 to 100 ° C. from the viewpoint of the balance between precipitation efficiency and cost.
  • Precipitated fibrous copper fine particles can be recovered by solid-liquid separation by methods such as filtration, centrifugation, and pressure levitation. Further, if necessary, the recovered fibrous copper fine particles may be washed or dried. In addition, when taking out fibrous copper fine particles, since the surface is easy to be oxidized, it is preferable to work in inert gas atmosphere (for example, nitrogen gas atmosphere).
  • inert gas atmosphere for example, nitrogen gas atmosphere
  • an inert gas atmosphere for example, a nitrogen gas atmosphere, or a solution in which a trace amount of a reducing compound is dissolved, or an organic substance having a copper antioxidant function. It is preferable to re-disperse and store in a solution dissolved in a small amount.
  • the fibrous copper fine particles precipitated by the above method are recovered by solid-liquid separation, and then washed with a solution in which a trace amount of a reducing compound such as ascorbic acid is dissolved.
  • the coated fibrous copper fine particles of the present invention may be obtained by subjecting to a step of coating with a metal other than copper immediately after washing without storing in the state of fine particles. This method is more preferable from the viewpoint of suppressing the surface oxidation of the fibrous copper fine particles.
  • a conductive coating agent By mixing and dispersing the coated fibrous copper fine particles of the present invention in which the fibrous copper fine particles having a specific shape as described above are coated with a metal other than copper in a binder component and a solvent, A conductive coating agent can be made.
  • the binder component is not particularly limited.
  • acrylic resins acrylic silicone-modified resins, fluorine-modified acrylic resins, urethane-modified acrylic resins, epoxy-modified acrylic resins, etc.
  • polyester resins polyurethane resins, olefin resins
  • semi-synthetic polymer carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose
  • Cellulose derivatives such as water-soluble polymers such as synthetic polymer polyvinyl alcohol, polyacrylic acid polymer, polyacrylamide, polyethylene oxide, polyvinyl pyrrolidone, etc. Rukoto can.
  • the solvent is not particularly limited, and examples thereof include organic solvents such as water, alcohols, glycols, cellosolves, ketones, esters, ethers, amides, and hydrocarbons. These can be used alone or in combination of two or more. Among these, it is preferable to use a solvent mainly composed of water or alcohols.
  • the blending ratio of the coated fibrous copper fine particles and the binder is a volume ratio (A / B) between the volume of the coated fibrous copper fine particles (A) and the volume of the binder (B). It is preferably 1/100 to 5/1, more preferably 1/20 to 1/1.
  • the conductive coating agent obtained or the conductive film obtained from the coating agent can conduct electricity. May be low.
  • the binder is so small that the volume ratio exceeds 5/1, the surface smoothness and transparency of the conductive film may be inferior, or the conductive coating agent may be used as a base material. In some cases, the adhesion with the substrate may be reduced.
  • the solid content in the conductive coating agent of the present invention is a concentration that is excellent in balance between conductivity and handleability. Therefore, 1 to 99% by mass is preferable, and 1 to 50% by mass is more preferable.
  • the viscosity at 20 ° C. of the conductive coating agent of the present invention is preferably 0.5 to 100 mPa ⁇ s, preferably 1 to 50 mPa ⁇ s from the viewpoint of excellent handling properties and ease of application to a substrate. It is more preferable that
  • an aldehyde-based, epoxy-based, melamine-based, or isocyanate-based cross-linking agent may be used as necessary within the range not impairing the effects of the present invention.
  • the conductive film of the present invention can be obtained by forming the conductive coating agent of the present invention into a film. Furthermore, the conductive film of the present invention can be obtained by forming the conductive film on a substrate.
  • the conductive film and conductive film of the present invention are excellent in both transparency and conductivity.
  • the conductive coating agent of the present invention is applied on the surface of a substrate such as a plastic film, then dried, and then cured as necessary to form a film.
  • a phase film forming method can be mentioned.
  • Application methods include roll coating, bar coating, dip coating, spin coating, casting, die coating, blade coating, gravure coating, curtain coating, spray coating, and doctor coating. Can be used.
  • the film thickness of the conductive film may be, for example, about 0.1 to 10 ⁇ m from the viewpoint of practicality.
  • a conductive film or conductive film containing the coated fibrous copper fine particles of the present invention only the coated fibrous copper fine particles of the present invention are applied on the surface of a substrate such as a plastic film and necessary.
  • a method of forming a coating layer for protecting the coated coated copper fine particles can also be used.
  • the dissolved oxygen concentration 1 is the dissolved oxygen concentration in the alkaline aqueous solution measured as described above.
  • the dissolved oxygen concentration 2 is the dissolved oxygen concentration in the aqueous solution 10 minutes after the addition of the reducing compound, measured as described above.
  • Dissolved oxygen concentration in alkaline aqueous solution Measured using a dissolved oxygen meter “DO-5509” (manufactured by Lutron).
  • Aspect ratio of fibrous copper fine particles and copper granules The aspect ratio of the fibrous copper fine particles and the copper granules was calculated by dividing the length obtained in (1) by the minor axis.
  • Number of copper particles per fibrous copper fine particle Prepared an aggregate of fibrous copper fine particles, and in order to prevent the fibrous copper fine particles from sticking too much together, it was lightly solved using an ultrasonic dispersing device. . Thereafter, observation was performed using a digital microscope (manufactured by Keyence Corporation, “VHX-1000, VHX-D500 / 510”). 100 fibrous copper particles are selected from the aggregate, the number of copper particles in the fibrous copper particles is counted, and the number of copper particles is divided by the number of fibrous copper particles (100). Thus, the number of copper particles per one fibrous copper fine particle was calculated.
  • Coating amount of metal on fibrous copper fine particles The coated fibrous copper fine particles obtained in the examples were collected in a glass beaker, dissolved and diluted with nitric acid, and used as a measurement solution. The measurement solution was subjected to quantitative evaluation by ICP (manufactured by Nippon Jarrell Ash). And the metal coating amount with respect to fibrous copper microparticles was computed from the content ratio of each metal (namely, metals other than copper and copper) quantified. In addition, in the Example of this specification, since silver is used as metals other than copper, the metal coating amount means the silver coating amount.
  • volume specific resistance and resistance value change of coated fibrous copper fine particles (unit: ⁇ ⁇ cm)
  • the coated fibrous copper fine particles obtained in the examples or the uncoated fibrous copper fine particles used in the comparative examples are dispersed in an ascorbic acid aqueous solution (10% by mass), and then pressure filtration with nitrogen ( Filter: PTFE membrane filter having a pore size of 1 ⁇ m (manufactured by Advantech Co., Ltd.), and a sample in which fine particles were laminated in a sheet form on the filter was prepared.
  • the obtained sample was dried at atmospheric pressure for 30 minutes with a drier set at 60 ° C., and then subjected to a vacuum drying treatment for 1 hour.
  • a resistivity meter manufactured by Dia Instruments, Loresta AP, MCP-T400
  • the molar ratio of hydroxide ions to copper ions in the aqueous solution was 4500/1.
  • the precipitated fibrous copper fine particles are recovered by pressure filtration with nitrogen (PTFE membrane filter having a pore size of 1 ⁇ m, manufactured by Advantech), and washed once with an aqueous corcorbic acid solution (10% by mass) and three times with pure water. And drying in a dryer set at 50 ° C. This was designated as “uncoated fibrous copper particles 1”. With respect to the uncoated fibrous copper fine particles 1, the above 3. 4. And 5. was evaluated. The evaluation results are shown in Table 1. The evaluation results are shown in the item of the shape of the fibrous copper fine particles in Examples 1 to 4 and Comparative Example 1.
  • the obtained precipitate was recovered in the same manner as in Example 1, and this was designated as “uncoated fibrous copper fine particles 2”. With respect to the uncoated fibrous copper fine particles 2, the above 3. 4. And 5. was evaluated. The evaluation results are shown in Table 1. The evaluation results are shown in the item of the shape of the fibrous copper fine particles in Example 5 and Comparative Example 2.
  • Example 1 In a plastic container containing a stirrer chip, 0.01 g of “uncoated fibrous copper particles 1” and 18 g of an ascorbic acid aqueous solution (10 mass%) were added to prepare a suspension. While stirring the suspension at room temperature at 700 rpm, 2 g of a pre-dip solution for substitution type electroless silver plating (Shikoku Kasei Kogyo Co., Ltd., “SSP-700P”) was added, and stirring was continued for 5 minutes after the addition. did.
  • a pre-dip solution for substitution type electroless silver plating Shikoku Kasei Kogyo Co., Ltd., “SSP-700P”
  • the suspension is subjected to pressure filtration with nitrogen (filter: PTFE membrane filter with a pore size of 1 ⁇ m, manufactured by Advantech) and washed with ion-exchanged water, whereby fine particles are formed in a sheet form on the filter.
  • filter PTFE membrane filter with a pore size of 1 ⁇ m, manufactured by Advantech
  • ion-exchanged water washed with ion-exchanged water, whereby fine particles are formed in a sheet form on the filter.
  • stacked on was produced.
  • the sample was dried in a drier set at 60 ° C., and thus, fibrous copper fine particles coated with silver were obtained in a state of being deposited on the filter. With respect to the obtained coated fibrous copper fine particles, the above-mentioned 6., 7. and 8. Was evaluated.
  • the evaluation results are shown in Table 1.
  • Example 2 In Example 1, a solution obtained by mixing 0.5 g of a substitution type electroless silver plating solution (“SSP-700M” manufactured by Shikoku Kasei Kogyo Co., Ltd.) and 19.5 g of ion-exchanged water was mixed into 1 g and 19 g, respectively.
  • SSP-700M substitution type electroless silver plating solution
  • ion-exchanged water 19.5 g
  • the coated fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1 except that the above was changed. Evaluation similar to Example 1 was performed with respect to the obtained coated fibrous copper fine particles. The evaluation results are shown in Table 1.
  • Example 3 a solution obtained by mixing 0.5 g of a substitutional electroless silver plating solution (“SSP-700M”, manufactured by Shikoku Kasei Kogyo Co., Ltd.) and 19.5 g of ion-exchanged water, Coated fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1 except that the amount was changed to 19.8 g. Evaluation similar to Example 1 was performed with respect to the obtained coated fibrous copper fine particles. The evaluation results are shown in Table 1.
  • SSP-700M substitutional electroless silver plating solution
  • Example 4 In Example 1, a solution obtained by mixing 0.5 g of a substitution-type electroless silver plating solution (“SSP-700M” manufactured by Shikoku Kasei Kogyo Co., Ltd.) and 19.5 g of ion-exchanged water was used. Except for changing to 19.9 g, fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1. Evaluation similar to Example 1 was performed with respect to the obtained coated fibrous copper fine particles. The evaluation results are shown in Table 1.
  • SSP-700M a substitution-type electroless silver plating solution manufactured by Shikoku Kasei Kogyo Co., Ltd.
  • Example 5 Except for using “uncoated fibrous copper particles 2” instead of “uncoated fibrous copper particles 1”, fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1. Evaluation similar to Example 1 was performed about items other than volume specific resistance with respect to the obtained coated fibrous copper fine particle. The evaluation results are shown in Table 1.
  • Example 1 The same evaluation as in Example 1 was performed on the “uncoated fibrous copper particles 1” without performing metal coating. The evaluation results are shown in Table 1.
  • Example 2 The same evaluation as in Example 1 was performed on items other than the volume resistivity without performing a coating treatment with metal on the “uncoated fibrous copper particles 2”. The evaluation results are shown in Table 1.
  • the volume resistivity was measured for the sample after the drying under reduced pressure using a resistivity meter (Dore Instruments, Loresta AP, MCP-T400). The initial volume resistivity value was 5.7 ⁇ 10 ⁇ 5 ( ⁇ ⁇ cm). Thereafter, the volume resistivity value after heat treatment at 180 ° C. for 1 hour was 5.0 ⁇ 10 ⁇ 5 ( ⁇ ⁇ cm).
  • the coated fibrous copper fine particles obtained in Examples 1 to 5 were simply obtained from fibrous copper fine particles having a length of 1 ⁇ m or more and an aspect ratio of 10 or more, and excellent in stability. Met.
  • the coated fibrous copper fine particles obtained in Examples 1 to 4 have a minor axis of 1 ⁇ m or less and an extremely large aspect ratio, a minor axis of 0.3 ⁇ m or more and an aspect ratio of 1.5 or less. It was obtained by coating fibrous copper fine particles with a small proportion of copper particles with silver. Therefore, compared with uncoated fibrous copper fine particles (Comparative Example 1), the volume specific resistance was a low value, that is, good conductivity was exhibited. The conductivity was almost the same as that of the fibrous silver fine particles (Comparative Example 3), and was comparable to the fibrous fine particles consisting of only silver.
  • Comparative Examples 1 and 2 the evaluation was performed using fibrous copper fine particles whose surface was not coated with a metal other than copper.
  • the fibrous copper fine particles did not have good characteristics in stability.
  • Examples 1 to 4 show for the first time that the silver coating amount on the fibrous copper fine particles having a length of 1 ⁇ m or more and an aspect ratio of 10 or more can be controlled.
  • the change in the volume resistivity value due to the heat treatment of the silver-coated fibrous copper fine particles in Examples 1 to 4 was almost the same as that of the fibrous silver fine particles shown in Comparative Example 3, and was a good characteristic.
  • Comparative Example 1 was a fibrous copper fine particle whose surface was not coated with a metal other than copper, the volume resistivity after the heat treatment was remarkably increased and the conductivity was deteriorated.
  • a conductive coating agent By using the coated fibrous copper fine particles of the present invention, a conductive coating agent, a conductive film and a conductive film having both excellent conductivity and transparency can be obtained, which is very useful.

Abstract

The present invention relates to coated fibrous copper microparticles, in which at least a part of each of fibrous copper microparticles is coated with a metal other than copper, said coated fibrous copper microparticles being characterized in that each of the fibrous copper microparticles has a length of 1 μm or longer and an aspect ratio of 10 or greater.

Description

被覆繊維状銅微粒子、並びに該被覆繊維状銅微粒子を含む導電性コーティング剤および導電性フィルムCoated fibrous copper fine particles, and conductive coating agent and conductive film containing the coated fibrous copper fine particles
　本発明は、被覆繊維状銅微粒子、並びに該被覆繊維状銅微粒子を含む導電性コーティング剤および導電性フィルムに関するものである。 The present invention relates to coated fibrous copper fine particles, and a conductive coating agent and a conductive film containing the coated fibrous copper fine particles.
　球状の銅微粒子は導電性に優れ、かつ安価な材料であることから、導電性コーティング剤などの原料などとして広く用いられている。このような導電性コーティング剤は、プリント配線板などにおいて各種印刷法を用いて回路を形成するための材料や、各種の電気的接点部材などにおいて幅広く利用されている。 Spherical copper fine particles are widely used as raw materials for conductive coating agents and the like because they are excellent in conductivity and inexpensive. Such conductive coating agents are widely used in materials for forming circuits using various printing methods on printed wiring boards and the like, various electrical contact members, and the like.
　そして、このような銅微粒子の導電性や安定性をさらに向上させるために、例えば、該銅微粒子の表面に対し、銀に代表される銅以外の金属を被覆させることが様々に提案されている。このような技術は、例えば、特公昭５７－５９２８３号公報、特公平２－４６６４１号公報または特許第４２２３７５４号明細書に開示されている。これらの被覆された球状銅微粒子は、銀などの高価な貴金属のみからなる金属微粒子と比較しても、その導電性に遜色が無く、しかも製造コストを低減することができるため、価値が高いものである。 In order to further improve the conductivity and stability of such copper fine particles, for example, various proposals have been made to coat the surface of the copper fine particles with a metal other than copper typified by silver. . Such a technique is disclosed in, for example, Japanese Patent Publication No. 57-59283, Japanese Patent Publication No. 2-46641, or Japanese Patent No. 4223754. These coated spherical copper fine particles have high value compared to metal fine particles made only of expensive noble metals such as silver, because their conductivity is inferior and manufacturing costs can be reduced. It is.
　近年、透明導電性フィルムに代表される透明性を有する導電材料（透明導電材料）を必要とする用途（例えば、タッチパネルや、フラットパネルディスプレイなどの用途）が急激に拡大している。それにともない、導電性コーティング剤や導電性皮膜などの透明導電材料において、導電材として球状銅微粒子を使用することが検討されている。そして、導電性コーティング剤に対しては導電性皮膜を形成しうる性能が要求される。 In recent years, applications requiring a transparent conductive material (transparent conductive material) typified by a transparent conductive film (for example, applications such as touch panels and flat panel displays) are rapidly expanding. Accordingly, it has been studied to use spherical copper fine particles as a conductive material in a transparent conductive material such as a conductive coating agent or a conductive film. And the performance which can form a conductive film is requested | required with respect to a conductive coating agent.
　しかしながら、上記したような、従来の銀などにて被覆された球状銅微粒子を含有する導電性コーティング剤を、例えばタッチパネル等に利用される透明導電性フィルムの導電層形成用コート材として適用した場合においては、十分な導電性を確保するために、銀にて被覆された球状銅微粒子の含有量を多くすると、導電層における透明性が低下してしまうという問題がある。逆に、透明性を確保するために、銀にて被覆された銅微粒子の含有量を少なくさせると、導電層における導電性が低下してしまうという問題がある。すなわち、従来から知られている、銀などの貴金属にて被覆された球状銅微粒子を含有する透明導電材料においては、透明導電性フィルムの導電層に対して要求される導電性及び透明性のいずれをも満足させることは困難である。 However, when the conductive coating agent containing spherical copper fine particles coated with conventional silver as described above is applied as a coating material for forming a conductive layer of a transparent conductive film used for a touch panel, for example. In order to ensure sufficient conductivity, there is a problem that if the content of the spherical copper fine particles coated with silver is increased, the transparency in the conductive layer is lowered. Conversely, if the content of the copper fine particles coated with silver is reduced in order to ensure transparency, there is a problem that the conductivity in the conductive layer is lowered. That is, in the conventionally known transparent conductive material containing spherical copper fine particles coated with a noble metal such as silver, any one of conductivity and transparency required for the conductive layer of the transparent conductive film is used. Is difficult to satisfy.
　上記のように、銀などの貴金属にて被覆された球状銅微粒子を、導電材として、透明導電材料に含有させたとしても、透明導電材料における導電性及び透明性のいずれをも満足させることが困難である。また、銀などの貴金属のみからなる微粒子は高価であり、コスト的に不利な場合がある。さらに、該微粒子を得るためには、球状の微粒子を分離する工程が必要となるため、このような金属微粒子の製造には、非常に手間がかかるという問題があった。 As described above, even if spherical copper fine particles coated with a noble metal such as silver are contained in a transparent conductive material as a conductive material, both the conductivity and transparency of the transparent conductive material can be satisfied. Have difficulty. Further, fine particles made only of noble metals such as silver are expensive and may be disadvantageous in terms of cost. Further, in order to obtain the fine particles, a step of separating the spherical fine particles is required, and thus there has been a problem that it takes much time to manufacture such metal fine particles.
　そこで、本発明の目的は、上記課題を解決するものであって、透明導電材料に含有された場合に、導電性及び透明性のいずれにも優れる被覆繊維状銅微粒子を提供することである。 Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide coated fibrous copper fine particles that are excellent in both conductivity and transparency when contained in a transparent conductive material.
　そこで、本発明者らは、上記課題を解決するために鋭意研究した結果、銀に比べて大幅に安価な金属である銅から形成された繊維状銅微粒子に対し、銀などの銅以外の金属が被覆されてなる被覆繊維状銅微粒子は、透明導電材料に含有された場合に、導電性及び透明性のいずれにも優れる導電材となり得ることを初めて見出し、本発明の完成に至った。 Therefore, as a result of intensive studies to solve the above problems, the present inventors have found that metal other than copper, such as silver, with respect to fibrous copper fine particles formed from copper, which is a metal that is significantly less expensive than silver. It was found for the first time that the coated fibrous copper fine particles formed by coating can be a conductive material excellent in both conductivity and transparency when contained in a transparent conductive material, and the present invention has been completed.
　すなわち、本発明は下記を趣旨とするものである。
（１）繊維状銅微粒子の少なくとも一部が銅以外の金属で被覆された被覆繊維状銅微粒子であって、該繊維状銅微粒子の長さが１μｍ以上であり、かつアスペクト比が１０以上であることを特徴とする被覆繊維状銅微粒子。
（２）繊維状銅微粒子の短径が１μｍ以下であり、該繊維状銅微粒子における、短径が０．３μｍ以上かつアスペクト比が１．５以下である銅粒状体の存在割合が繊維状銅微粒子１本あたり０．１個以下であることを特徴とする（１）の被覆繊維状銅微粒子。
（３）（１）又は（２）の被覆繊維状銅微粒子を含有することを特徴とする導電性コーティング剤。
（４）（１）又は（２）の被覆繊維状銅微粒子を含有することを特徴とする導電性皮膜。
（５）（４）の導電性皮膜を基材上に有することを特徴とする導電性フィルム。 That is, the present invention has the following purpose.
(1) A coated fibrous copper fine particle in which at least a part of the fibrous copper fine particle is coated with a metal other than copper, the length of the fibrous copper fine particle is 1 μm or more, and the aspect ratio is 10 or more. Coated fibrous copper fine particles characterized by being.
(2) The minor axis of the fibrous copper fine particles is 1 μm or less, and the proportion of the copper particles having a minor axis of 0.3 μm or more and an aspect ratio of 1.5 or less in the fibrous copper fine particles is fibrous copper. The coated fibrous copper fine particles according to (1), wherein the number is 0.1 or less per fine particle.
(3) A conductive coating agent comprising the coated fibrous copper fine particles of (1) or (2).
(4) A conductive film comprising the coated fibrous copper fine particles of (1) or (2).
(5) A conductive film comprising the conductive film of (4) on a substrate.
　本発明の被覆繊維状銅微粒子は、繊維状銅微粒子の表面の少なくとも一部が銅以外の金属で被覆された被覆繊維状銅微粒子であって、該繊維状銅微粒子の長さが１μｍ以上であり、かつアスペクト比が１０以上であるという特定の形状及び構成を有している。そのため、このような被覆繊維状銅微粒子を用いることにより、優れた導電性と透明性とを兼ね備えた、導電性コーティング剤、導電性皮膜及び導電性フィルムを得ることができる。 The coated fibrous copper fine particles of the present invention are coated fibrous copper fine particles in which at least a part of the surface of the fibrous copper fine particles is coated with a metal other than copper, and the length of the fibrous copper fine particles is 1 μm or more. And has a specific shape and configuration with an aspect ratio of 10 or more. Therefore, by using such coated fibrous copper fine particles, it is possible to obtain a conductive coating agent, a conductive film and a conductive film having both excellent conductivity and transparency.
本発明の被覆繊維状銅微粒子のデジタルマイクロスコープによる観察図である。It is an observation figure by the digital microscope of the covering fibrous copper fine particle of this invention.
  以下、本発明を詳細に説明する。
　本発明の被覆繊維状銅微粒子は、繊維状銅微粒子の表面の少なくとも一部が銅以外の金属で被覆された被覆繊維状銅微粒子であって、該繊維状銅微粒子の長さが１μｍ以上であり、かつアスペクト比が１０以上であるものである。 Hereinafter, the present invention will be described in detail.
The coated fibrous copper fine particles of the present invention are coated fibrous copper fine particles in which at least a part of the surface of the fibrous copper fine particles is coated with a metal other than copper, and the length of the fibrous copper fine particles is 1 μm or more. Yes, and the aspect ratio is 10 or more.
　本発明の被覆繊維状銅微粒子は、上述のように、繊維状銅微粒子の表面が銅以外の金属にて被覆されてなるものであり、図１に示すように、金属による被覆後も、繊維形状が維持されている。銅以外の金属にて被覆された繊維状銅微粒子は、未被覆の繊維状銅微粒子と比較すると、溶媒中や大気中での安定性に優れるものである。繊維状銅微粒子を被覆するための銅以外の金属としては、貴金属元素（金・白金・銀・パラジウム・ロジウム・イリジウム・ルテニウム・オスミウム等）や卑金属元素（鉄・コバルト・錫等）などが挙げられる。これらは、１種で用いられてもよいし、複数種が組み合わせられて用いられてもよい。なかでも、導電性及び安定性の観点から、少なくとも銀を用いることが好ましい。 As described above, the coated fibrous copper fine particles of the present invention are obtained by coating the surface of the fibrous copper fine particles with a metal other than copper. As shown in FIG. The shape is maintained. Fibrous copper fine particles coated with a metal other than copper are superior in stability in a solvent or in the air as compared with uncoated fibrous copper fine particles. Examples of metals other than copper for coating the fibrous copper fine particles include noble metal elements (gold, platinum, silver, palladium, rhodium, iridium, ruthenium, osmium, etc.) and base metal elements (iron, cobalt, tin, etc.). It is done. These may be used alone or in combination of two or more. Among these, at least silver is preferably used from the viewpoints of conductivity and stability.
　未被覆の繊維状銅微粒子に対して、銀などの銅以外の金属を被覆する方法としては、特に限定されるものではないが、無電解メッキ法が好ましく用いられる。無電解メッキ法を採用して、繊維状銅微粒子の表面に対して銅以外の金属を被覆するためには、例えば銀を被覆させる場合には、硝酸銀、炭酸アンモニウム塩あるいはエチレンジアミン四酢酸塩の銀錯塩溶液を用い、繊維状銅微粒子の表面に銀を置換析出させる方法；あるいは、キレート化剤溶液に繊維状銅微粒子を分散し、該分散液に硝酸銀溶液を加え、次いで還元剤を添加して、該繊維状銅粒子の表面に対して、銀被膜を析出させる方法等を用いることができる。 The method for coating uncoated fibrous copper fine particles with a metal other than copper, such as silver, is not particularly limited, but an electroless plating method is preferably used. In order to coat the surface of the fibrous copper fine particles with a metal other than copper by adopting the electroless plating method, for example, when silver is coated, silver nitrate, ammonium carbonate or ethylenediaminetetraacetate silver A method of substituting and precipitating silver on the surface of the fibrous copper fine particles using a complex salt solution; or, dispersing the fibrous copper fine particles in the chelating agent solution, adding a silver nitrate solution to the dispersion, and then adding a reducing agent. A method of depositing a silver coating on the surface of the fibrous copper particles can be used.
　また、未被覆の繊維状銅微粒子に対し、銅以外の金属としての金を被覆するためには、例えば金源として、塩化金酸やシアン化金カリウム等を用い、該繊維状銅微粒子の表面に対して、金被膜を析出させるという手法を採用してもよい。未被覆の繊維状銅微粒子に対してニッケルを被覆するためには、例えばニッケル源として、塩化ニッケルや酢酸ニッケル等を用い、該繊維状銅微粒子の表面に対して、ニッケル被膜を析出させるという手法を採用してもよい。 Moreover, in order to coat | cover gold | metal | money as metals other than copper with respect to uncoated fibrous copper microparticles, for example, chloroauric acid or potassium gold cyanide is used as a gold source, and the surface of the fibrous copper microparticles In contrast, a technique of depositing a gold film may be employed. In order to coat nickel on uncoated fibrous copper fine particles, for example, nickel chloride or nickel acetate is used as a nickel source, and a nickel coating is deposited on the surface of the fibrous copper fine particles. May be adopted.
　金属が被覆されていない状態の（つまり、未被覆の）繊維状銅微粒子について述べる。
　繊維状銅微粒子の長さは１μｍ以上であることが必要であり、５μｍ以上であることが好ましく、１０μｍ以上であることがより好ましい。繊維状銅微粒子の長さが１μｍ未満であると、本発明の被覆繊維状銅微粒子を含む透明導電材料においては、良好な導電性と透明性とを両立させることが困難になる。一方、本発明の被覆繊維状銅微粒子を含む導電性皮膜や導電性フィルムを形成する際のコーティング剤のハンドリングの観点からは、繊維状微粒子の長さが５００μｍを超えないことが好ましい場合がある。 The fibrous copper fine particles not coated with metal (that is, uncoated) will be described.
The length of the fibrous copper fine particles needs to be 1 μm or more, preferably 5 μm or more, and more preferably 10 μm or more. When the length of the fibrous copper fine particles is less than 1 μm, it is difficult to achieve both good conductivity and transparency in the transparent conductive material containing the coated fibrous copper fine particles of the present invention. On the other hand, it may be preferable that the length of the fibrous fine particles does not exceed 500 μm from the viewpoint of handling the coating agent when forming the conductive film or conductive film containing the coated fibrous copper fine particles of the present invention. .
　繊維状銅微粒子の短径は１μｍ以下であることが好ましく、０．５μｍ以下であることがより好ましく、０．２μｍ以下であることがさらに好ましく、０．１μｍ以下であることが特に好ましい。繊維状銅微粒子の短径が１μｍを超えると、本発明の被覆繊維状銅微粒子を含有する透明導電材料においては、透明性に劣る場合がある。 The minor axis of the fibrous copper fine particles is preferably 1 μm or less, more preferably 0.5 μm or less, further preferably 0.2 μm or less, and particularly preferably 0.1 μm or less. If the short diameter of the fibrous copper fine particles exceeds 1 μm, the transparent conductive material containing the coated fibrous copper fine particles of the present invention may be inferior in transparency.
　繊維状銅微粒子のアスペクト比（繊維状体の長さ／繊維状体の短径）は、１０以上であることが必要であり、１００以上であることが好ましく、３００以上であることがより好ましい。繊維状銅微粒子のアスペクト比が１０未満であると（つまり、球状に近いものであると）、本発明の被覆繊維状銅微粒子を含む透明導電材料においては、透明性と導電性とを両立させることが困難になる。 The aspect ratio of the fibrous copper fine particles (the length of the fibrous body / the short diameter of the fibrous body) needs to be 10 or more, preferably 100 or more, and more preferably 300 or more. . When the aspect ratio of the fibrous copper fine particles is less than 10 (that is, close to spherical), the transparent conductive material containing the coated fibrous copper fine particles of the present invention achieves both transparency and conductivity. It becomes difficult.
　本発明の被覆繊維状銅微粒子においては、その全ての表面が銅以外の金属で被覆されていることが好ましいが、金属による被覆がなされておらず銅が表面に露出している部分があってもよい。被覆繊維状銅微粒子における、銅以外の被覆金属の含有量としては、被覆繊維状銅微粒子全体の質量に対して、１～５０質量％が好ましく、１０～５０質量％がより好ましく、１５～３０質量％がさらに好ましい。１質量％未満であると、金属を被覆させることにより奏される効果である導電性の向上が不十分な場合がある。一方、５０質量％を超えると、銅以外の金属の被覆による材料費が増加したり被覆繊維状銅微粒子の短径が増大したりする可能性がある。なお、金属の被覆量は、例えば、本発明の被覆繊維状銅微粒子を強酸に溶解させて測定溶液を得、この溶液に対してＩＣＰ（高周波誘導結合プラズマ）による測定をおこなうことにより求めることが出来る。 In the coated fibrous copper fine particles of the present invention, it is preferable that the entire surface is coated with a metal other than copper, but there is a portion where copper is not exposed and is not coated with metal. Also good. The content of the coating metal other than copper in the coated fibrous copper fine particles is preferably 1 to 50% by mass, more preferably 10 to 50% by mass, and more preferably 15 to 30% with respect to the total mass of the coated fibrous copper fine particles. More preferred is mass%. If the content is less than 1% by mass, the improvement in conductivity, which is an effect produced by coating the metal, may be insufficient. On the other hand, if it exceeds 50% by mass, there is a possibility that the material cost due to the coating of a metal other than copper increases or the short diameter of the coated fibrous copper fine particles increases. The metal coating amount can be obtained, for example, by dissolving the coated fibrous copper fine particles of the present invention in a strong acid to obtain a measurement solution, and measuring this solution by ICP (high frequency inductively coupled plasma). I can do it.
　繊維状銅微粒子、及び後述の銅粒状体の、短径及び長さ（長径）を求める方法、および繊維状銅微粒子１本あたりの銅粒状体の個数を算出する方法は、以下のようなものである。
　つまり、透過型電子顕微鏡（ＴＥＭ）や走査型電子顕微鏡（ＳＥＭ）などを用い、繊維状銅微粒子の集合体を観察する。繊維状銅微粒子の観察には、例えば、デジタルマイクロスコープ（キーエンス社製、「ＶＨＸ－１０００、ＶＨＸ－Ｄ５００／５１０」）などを用いることができる。 The method for obtaining the short diameter and length (major diameter) of the fibrous copper fine particles and the copper particles described later, and the method for calculating the number of copper particles per fibrous copper fine particle are as follows. It is.
That is, an aggregate of fibrous copper fine particles is observed using a transmission electron microscope (TEM), a scanning electron microscope (SEM), or the like. For example, a digital microscope (manufactured by Keyence Corporation, “VHX-1000, VHX-D500 / 510”) or the like can be used for observing the fibrous copper fine particles.
　そして、該集合体から１００本の繊維状銅微粒子を選択する。これらの繊維状銅微粒子、及び繊維状銅微粒子に付着あるいは接触している銅粒状体の、短径及び長さをそれぞれ測定し、これらの平均値をもって、短径及び長さとすることができる。また、上記のようにして求めた長さを短径で除することにより、繊維状銅微粒子及び銅粒状体のアスペクト比を算出することができる。さらに、存在する銅粒状体の個数をカウントし、銅粒状体の個数を繊維状銅微粒子の本数（１００本）で除することにより、繊維状銅微粒子１本あたりの銅粒状体の個数を算出することができる。 Then, 100 fibrous copper fine particles are selected from the aggregate. The short diameter and the length of the fibrous copper fine particles and the copper particles adhering to or in contact with the fibrous copper fine particles are measured, and the average value of these can be used as the short diameter and the length. Moreover, the aspect ratio of the fibrous copper fine particles and the copper particulates can be calculated by dividing the length obtained as described above by the minor axis. Further, by counting the number of copper particles present and dividing the number of copper particles by the number of fibrous copper particles (100), the number of copper particles per fibrous copper particle is calculated. can do.
　ここで、本発明の繊維状銅微粒子を観察するに際し、繊維状銅微粒子が重なり合って密集している場合は、繊維状銅微粒子および銅粒状体の形状を正確に評価することができない場合がある。そのため、このような場合は、超音波分散装置などを用い、隣り合う繊維状銅微粒子同士が密着しない程度になるまで密集している繊維状銅微粒子を解すことができる。 Here, when observing the fibrous copper fine particles of the present invention, if the fibrous copper fine particles overlap and are densely packed, the shapes of the fibrous copper fine particles and the copper particulates may not be accurately evaluated. . Therefore, in such a case, the fibrous copper fine particles that are densely packed until the adjacent fibrous copper fine particles are not in close contact with each other can be solved by using an ultrasonic dispersion device or the like.
　未被覆の繊維状銅微粒子においては、短径が０．３μｍ以上かつアスペクト比が１．５以下である銅粒状体の存在割合が繊維状銅微粒子１本あたり０．１個以下であることが好ましく、０．０８個以下であることがより好ましく、０．０５個以下であることがさらに好ましく、全く存在しないことが最も好ましい。上記の銅粒状体が繊維状銅微粒子１本あたり０．１個を超えて存在する場合は、本発明の被覆繊維状銅微粒子を含む透明導電材料において、透明性に劣る場合がある。 In the uncoated fibrous copper fine particles, the proportion of copper particles having a minor axis of 0.3 μm or more and an aspect ratio of 1.5 or less is 0.1 or less per fibrous copper fine particle. The number is preferably 0.08 or less, more preferably 0.05 or less, and most preferably none. When the above copper particles are present in excess of 0.1 per fibrous copper fine particle, the transparent conductive material containing the coated fibrous copper fine particle of the present invention may be inferior in transparency.
　なお、透明性に影響を与える銅粒状体の短径は０．３μｍ以上であり、同アスペクト比（銅粒状体の長さ／銅粒状体の短径）は１．５以下のものである。 In addition, the minor axis of the copper granule that affects the transparency is 0.3 μm or more, and the aspect ratio (the length of the copper granule / the minor axis of the copper granule) is 1.5 or less.
　上記のような未被覆の繊維状銅微粒子を製造するには、例えば、以下のような方法が用いられる。すなわち、銅イオン、アルカリ性化合物、銅イオンと安定な錯体を形成しうる含窒素化合物及び還元性化合物を含有する水溶液から繊維状銅微粒子を析出させるという方法が用いられる。このとき、還元性化合物として、アルカリ水溶液中の溶存酸素と反応しないものを使用することが好ましい。 In order to produce uncoated fibrous copper fine particles as described above, for example, the following method is used. That is, a method of depositing fibrous copper fine particles from an aqueous solution containing a copper ion, an alkaline compound, a nitrogen-containing compound capable of forming a stable complex with copper ion, and a reducing compound is used. At this time, it is preferable to use a reducing compound that does not react with dissolved oxygen in the alkaline aqueous solution.
　還元性化合物として、アルカリ水溶液中の溶存酸素と反応するものを用いると、得られる繊維状銅微粒子においては、銅粒状体の存在割合が、繊維状銅微粒子１本あたり０．１個を超えてしまい、つまり、銅粒状体が多数存在する繊維状銅微粒子しか得られない場合がある。 When a compound that reacts with dissolved oxygen in an alkaline aqueous solution is used as the reducing compound, in the obtained fibrous copper fine particles, the presence ratio of copper particulates exceeds 0.1 per one fibrous copper fine particle. In other words, only fibrous copper fine particles having a large number of copper particles may be obtained.
　ここで、「溶存酸素と反応しない還元性化合物」とは、以下の指標により定義される。
　まず、純水５００ｇに１０％水酸化ナトリウム水溶液を数滴添加し、ｐＨを１０．４に調整したアルカリ水溶液（水温２５℃）を調製する。このアルカリ水溶液の溶存酸素濃度を「溶存酸素濃度１」とする。具体的には、溶存酸素濃度１は、８．３ｍｇ／Ｌである。なお、溶存酸素濃度の測定には、例えば、溶存酸素計「ＤＯ－５５０９」（Ｌｕｔｒｏｎ社製）を用いる。 Here, the “reducing compound that does not react with dissolved oxygen” is defined by the following index.
First, several drops of a 10% sodium hydroxide aqueous solution are added to 500 g of pure water to prepare an alkaline aqueous solution (water temperature 25 ° C.) adjusted to pH 10.4. Let the dissolved oxygen concentration of this alkaline aqueous solution be "dissolved oxygen concentration 1". Specifically, the dissolved oxygen concentration 1 is 8.3 mg / L. For the measurement of the dissolved oxygen concentration, for example, a dissolved oxygen meter “DO-5509” (manufactured by Lutron) is used.
　その後、直径が７．０ｃｍの開放円筒型容器に、このアルカリ水溶液を１００ｍＬ入れ、次いで、上記のアルカリ水溶液に対して、０．５０ｍｏｌ／Ｌの濃度になるように還元性化合物を添加し、該水溶液が渦巻かない程度にマグネチックスターラーを用いて撹拌し、溶解させる。溶解後も引き続き撹拌を継続しながら、還元性化合物の添加後から、０．５分、５分、１０分、１５分及び３０分後に、水溶液中の溶存酸素濃度を測定する。そして、還元性化合物の添加後から１０分後の溶存酸素濃度を「溶存酸素濃度２」とする。 Thereafter, 100 mL of this alkaline aqueous solution is put into an open cylindrical container having a diameter of 7.0 cm, and then a reducing compound is added to the alkaline aqueous solution so as to have a concentration of 0.50 mol / L. Stir with a magnetic stirrer so that the aqueous solution does not vortex and dissolve. The dissolved oxygen concentration in the aqueous solution is measured 0.5 minutes, 5 minutes, 10 minutes, 15 minutes and 30 minutes after the addition of the reducing compound while continuing stirring after dissolution. The dissolved oxygen concentration 10 minutes after the addition of the reducing compound is defined as “dissolved oxygen concentration 2”.
　そして、以下の式（１）により、数値Ａを求める。
Ａ＝（溶存酸素濃度２）／（溶存酸素濃度１）　　（１）
　本発明においては、（１）式にて得られた数値Ａが０．５以上である還元性化合物を「溶存酸素と反応しない還元性化合物」と定義する。そして、数値Ａが０．５未満である還元性化合物を「溶存酸素と反応する還元性化合物」と定義する。 And the numerical value A is calculated | required by the following formula | equation (1).
A = (Dissolved oxygen concentration 2) / (Dissolved oxygen concentration 1) (1)
In the present invention, a reducing compound having a numerical value A of 0.5 or more obtained by the formula (1) is defined as “a reducing compound that does not react with dissolved oxygen”. And the reducing compound whose numerical value A is less than 0.5 is defined as "the reducing compound which reacts with dissolved oxygen".
　溶存酸素と反応しない還元性化合物としては、アスコルビン酸、エリソルビン酸、グルコース又はヒドロキシルアンモニウム塩などが挙げられる。これらの溶存酸素と反応しない還元性化合物の数値Ａは、いずれも０．５以上である。なかでも、アスコルビン酸、エリソルビン酸及びグルコースから選ばれる１種以上を用いることが好ましく、アスコルビン酸を用いることが最も好ましい。 Examples of the reducing compound that does not react with dissolved oxygen include ascorbic acid, erythorbic acid, glucose, or hydroxylammonium salt. The numerical value A of these reducing compounds that do not react with dissolved oxygen is 0.5 or more. Especially, it is preferable to use 1 or more types chosen from ascorbic acid, erythorbic acid, and glucose, and it is most preferable to use ascorbic acid.
　従来技術においては、繊維状の銅微粒子を製造するに際し、一般に、反応溶液中に含有される還元性化合物としてヒドラジンを用いることで、該銅微粒子を析出させていた。しかしながら、ヒドラジンなどの「溶存酸素と反応する還元性化合物」を用いた場合は、銅粒状体の存在割合が増加した繊維状銅微粒子しか得られない場合がある。あるいは、繊維状銅微粒子自体を析出させることができない場合もある。 In the prior art, when producing fibrous copper fine particles, the copper fine particles are generally precipitated by using hydrazine as a reducing compound contained in the reaction solution. However, when a “reducing compound that reacts with dissolved oxygen” such as hydrazine is used, only fibrous copper fine particles with an increased proportion of copper particles may be obtained. Alternatively, there are cases where the fibrous copper fine particles themselves cannot be deposited.
　なお、従来用いられてきた還元性化合物であるヒドラジンにおいて、上記式（１）にて得られた数値Ａは０．０５程度である。 In addition, in the hydrazine which is a reducing compound conventionally used, the numerical value A obtained by the above formula (1) is about 0.05.
　本発明においては、繊維状銅微粒子を析出させるための水溶液中の溶存酸素濃度を高い範囲に維持することが好ましい。より具体的には、該水溶液に含有される水として、溶存酸素濃度が１ｍｇ／Ｌ以上であるものを使用することが好ましく、３ｍｇ／Ｌ以上であるものを使用することがより好ましい。溶存酸素濃度が１ｍｇ／Ｌ未満である水を用いると、繊維状銅微粒子１本あたりの銅粒状体の割合が０．１個を超えるものとなり、ひいては、透明導電材料などに含有された場合に、透明性に劣る繊維状銅微粒子しか得られない場合がある。 In the present invention, it is preferable to maintain the dissolved oxygen concentration in the aqueous solution for precipitating the fibrous copper fine particles in a high range. More specifically, the water contained in the aqueous solution is preferably one having a dissolved oxygen concentration of 1 mg / L or more, and more preferably 3 mg / L or more. When water having a dissolved oxygen concentration of less than 1 mg / L is used, the ratio of copper particles per fibrous copper fine particle exceeds 0.1, and as a result contained in a transparent conductive material or the like. In some cases, only fibrous copper fine particles having poor transparency can be obtained.
　上記のような還元性化合物は、水溶液中の銅イオンに対し０．５～５．０モル当量の割合で用いられることが好ましく、０．７５～３．０モル当量の割合で用いられることがより好ましい。０．５モル当量未満の割合で用いられると、繊維状銅微粒子の形成効率が低下する場合がある。一方、５．０モル当量を超えて使用しても、繊維状銅微粒子の形成効果が飽和してしまい、コストなどの観点から好ましくない。 The reducing compound as described above is preferably used in a proportion of 0.5 to 5.0 molar equivalents relative to copper ions in the aqueous solution, and is preferably used in a proportion of 0.75 to 3.0 molar equivalents. More preferred. When used in a proportion of less than 0.5 molar equivalent, the formation efficiency of the fibrous copper fine particles may be lowered. On the other hand, even if it exceeds 5.0 molar equivalent, the formation effect of the fibrous copper fine particles is saturated, which is not preferable from the viewpoint of cost.
　銅イオンは、水溶性の銅塩を水に溶解させることにより生成することができる。水溶性の銅塩としては、硫酸銅、硝酸銅、塩化銅又は酢酸銅などが挙げられる。なかでも、本発明の繊維状銅微粒子の形成しやすさの点では、硫酸銅又は硝酸銅を好ましく用いることができる。 Copper ions can be generated by dissolving a water-soluble copper salt in water. Examples of the water-soluble copper salt include copper sulfate, copper nitrate, copper chloride, and copper acetate. Among these, copper sulfate or copper nitrate can be preferably used from the viewpoint of easy formation of the fibrous copper fine particles of the present invention.
　アルカリ性化合物としては、特に限定されるものではなく、水酸化ナトリウム、水酸化カリウムなどを用いることができる。 The alkaline compound is not particularly limited, and sodium hydroxide, potassium hydroxide and the like can be used.
　水溶液中における、アルカリ性化合物の濃度は１５～５０質量％とすることが好ましく、３０～５０質量％とすることがより好ましく、３５～４５質量％とすることがさらに好ましい。アルカリ性化合物の濃度が１５質量％未満であると、本発明の繊維状銅微粒子が形成されにくくなる場合がある。一方、該濃度が５０質量％を超えると、水溶液のハンドリングが困難となる場合がある。 The concentration of the alkaline compound in the aqueous solution is preferably 15 to 50% by mass, more preferably 30 to 50% by mass, and further preferably 35 to 45% by mass. When the concentration of the alkaline compound is less than 15% by mass, it may be difficult to form the fibrous copper fine particles of the present invention. On the other hand, when the concentration exceeds 50% by mass, it may be difficult to handle the aqueous solution.
　水溶液中における銅イオンの濃度は、上記アルカリ性化合物の水酸化物イオンと銅イオンとのモル比によって規定される。すなわち、（アルカリ性化合物の水酸化物イオン）／（銅イオン）が、モル比で、３０００／１～６０００／１の範囲となるように設定されることが好ましく、３０００／１～５０００／１の範囲に設定されることがより好ましい。該モル比が３０００／１未満であると、銅粒状体の形成を抑制することができず、ひいては、銅粒状体の存在割合が繊維状銅微粒子１本あたり０．１個を超えてしまう。あるいは、銅微粒子の形状が繊維状とならず、球状となってしまう場合がある。一方、モル比が６０００／１を超えると、繊維状銅微粒子の形成効率が悪くなってしまう場合がある。 The concentration of copper ions in the aqueous solution is defined by the molar ratio of hydroxide ions and copper ions of the alkaline compound. That is, (hydroxide ion of alkaline compound) / (copper ion) is preferably set to have a molar ratio of 3000/1 to 6000/1, preferably 3000/1 to 5000/1. More preferably, the range is set. When the molar ratio is less than 3000/1, the formation of the copper particles cannot be suppressed, and as a result, the existence ratio of the copper particles exceeds 0.1 per one fibrous copper fine particle. Alternatively, the shape of the copper fine particles may not be fibrous but spherical. On the other hand, if the molar ratio exceeds 6000/1, the formation efficiency of the fibrous copper fine particles may deteriorate.
　水溶液中で２価銅イオンと安定な錯体を形成する含窒素化合物としては、アンモニア、エチレンジアミン、又はトリエチレンテトラミンなどが挙げられる。なかでも、繊維状銅微粒子の形成しやすさの点では、エチレンジアミンを好ましく用いることができる。 Examples of the nitrogen-containing compound that forms a stable complex with a divalent copper ion in an aqueous solution include ammonia, ethylenediamine, or triethylenetetramine. Among these, ethylenediamine can be preferably used from the viewpoint of easy formation of fibrous copper fine particles.
　なお、上記の含窒素化合物は、繊維状銅微粒子の形成効率の観点から、銅イオン１モルに対して、１モル以上の割合で用いられることが好ましい。 In addition, it is preferable that said nitrogen-containing compound is used in the ratio of 1 mol or more with respect to 1 mol of copper ions from a viewpoint of the formation efficiency of fibrous copper microparticles.
　次いで、上述のような成分を含有する水溶液を、適宜な熱源で加熱し、次いで、上記水溶液の加熱を継続させる、あるいは、水溶液の液温を降下させることにより、所望の繊維状銅微粒子の析出を生じさせることができる。特に、後者の方法、すなわち、加熱後に液温を降下させる方法がより好ましい。 Next, the aqueous solution containing the above-described components is heated with an appropriate heat source, and then the heating of the aqueous solution is continued, or the liquid temperature of the aqueous solution is lowered to precipitate the desired fibrous copper fine particles. Can be generated. In particular, the latter method, that is, a method of lowering the liquid temperature after heating is more preferable.
　水溶液の加熱温度は特に限定されるものではないが、析出効率とコストとのバランスの観点から、５０～１００℃が好ましい。 The heating temperature of the aqueous solution is not particularly limited, but is preferably 50 to 100 ° C. from the viewpoint of the balance between precipitation efficiency and cost.
　析出した繊維状銅微粒子は、ろ過、遠心分離、加圧浮上法などの方法により固液分離して回収することができる。さらに必要に応じて、回収された繊維状銅微粒子に対して洗浄や乾燥などをおこなってもよい。なお、繊維状銅微粒子を取り出す際は、その表面が酸化されやすいため、不活性ガス雰囲気（例えば、窒素ガス雰囲気）下で作業をおこなうことが好ましい。 Precipitated fibrous copper fine particles can be recovered by solid-liquid separation by methods such as filtration, centrifugation, and pressure levitation. Further, if necessary, the recovered fibrous copper fine particles may be washed or dried. In addition, when taking out fibrous copper fine particles, since the surface is easy to be oxidized, it is preferable to work in inert gas atmosphere (for example, nitrogen gas atmosphere).
　また取り出された繊維状銅微粒子の保管に際しては、不活性ガス雰囲気、例えば窒素ガス雰囲気下で保管するか、微量の還元性化合物を溶解させた溶液、あるいは、銅の酸化防止機能を有する有機物を微量で溶解させた溶液などに再分散させて保管することが好ましい。 Also, when storing the taken-out fibrous copper fine particles, store in an inert gas atmosphere, for example, a nitrogen gas atmosphere, or a solution in which a trace amount of a reducing compound is dissolved, or an organic substance having a copper antioxidant function. It is preferable to re-disperse and store in a solution dissolved in a small amount.
　また、上記のような方法で析出させた繊維状銅微粒子を、固液分離して回収した後、水や、アスコルビン酸などの微量の還元性化合物を溶解させた溶液で洗浄し、繊維状銅微粒子の状態での保管をおこなうことなく、洗浄後、直ちに銅以外の金属で被覆する工程に付することにより、本発明の被覆繊維状銅微粒子を得てもよい。繊維状銅微粒子の表面酸化を抑制する観点からは、この方法がより好ましい。 In addition, the fibrous copper fine particles precipitated by the above method are recovered by solid-liquid separation, and then washed with a solution in which a trace amount of a reducing compound such as ascorbic acid is dissolved. The coated fibrous copper fine particles of the present invention may be obtained by subjecting to a step of coating with a metal other than copper immediately after washing without storing in the state of fine particles. This method is more preferable from the viewpoint of suppressing the surface oxidation of the fibrous copper fine particles.
　上述のような、特定の形状を有する繊維状銅微粒子が銅以外の金属で被覆されてなる本発明の被覆繊維状銅微粒子を、バインダ成分及び溶媒などに配合し分散させることによって、本発明の導電性コーティング剤を作製することができる。 By mixing and dispersing the coated fibrous copper fine particles of the present invention in which the fibrous copper fine particles having a specific shape as described above are coated with a metal other than copper in a binder component and a solvent, A conductive coating agent can be made.
　バインダ成分としては、特に限定はないが、例えば、アクリル系樹脂（アクリルシリコン変性樹脂、フッ素変性アクリル樹脂、ウレタン変性アクリル樹脂、エポキシ変性アクリル樹脂等）、ポリエステル系樹脂、ポリウレタン系樹脂、オレフィン系樹脂、アミド樹脂、イミド樹脂、エポキシ樹脂、シリコーン樹脂、酢酸ビニル系樹脂や、天然高分子のデンプン、ゼラチン、寒天等、半合成高分子のカルボキシメチルセルロース、ヒドロキシエチルセルロース、メチルセルロース、ヒドロキシエチルメチルセルロース、ヒドロキシプロピルメチルセルロース等のセルロース誘導体、合成高分子のポリビニルアルコール、ポリアクリル酸系高分子、ポリアクリルアミド、ポリエチレンオキサイド、ポリビニルピロリドン等の水溶性高分子等を用いることができる。 The binder component is not particularly limited. For example, acrylic resins (acrylic silicone-modified resins, fluorine-modified acrylic resins, urethane-modified acrylic resins, epoxy-modified acrylic resins, etc.), polyester resins, polyurethane resins, olefin resins Amide resin, imide resin, epoxy resin, silicone resin, vinyl acetate resin, natural polymer starch, gelatin, agar, etc., semi-synthetic polymer carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose Cellulose derivatives such as water-soluble polymers such as synthetic polymer polyvinyl alcohol, polyacrylic acid polymer, polyacrylamide, polyethylene oxide, polyvinyl pyrrolidone, etc. Rukoto can.
　上記溶媒としては、特に限定されないが、例えば、水、アルコール類、グリコール類、セロソルブ類、ケトン類、エステル類、エーテル類、アミド類、炭化水素類などの有機溶媒が挙げられる。これらは、単独であるいは二種以上を組み合わせて用いることができる。なかでも、水やアルコール類を主成分とする溶媒を用いることが好ましい。 The solvent is not particularly limited, and examples thereof include organic solvents such as water, alcohols, glycols, cellosolves, ketones, esters, ethers, amides, and hydrocarbons. These can be used alone or in combination of two or more. Among these, it is preferable to use a solvent mainly composed of water or alcohols.
　本発明の導電性コーティング剤における、被覆繊維状銅微粒子とバインダとの配合比率は、被覆繊維状銅微粒子の体積（Ａ）とバインダの体積（Ｂ）との体積比（Ａ／Ｂ）で、１／１００～５／１であることが好ましく、１／２０～１／１であることがより好ましい。被覆繊維状銅微粒子とバインダとの体積比が１／１００未満であるほどに被覆繊維状銅微粒子が少ないと、得られる導電性コーティング剤、あるいは該コーティング剤から得られる導電性皮膜などにおいて、導電性が低くなる場合がある。一方、体積比が５／１を超えるほどにバインダが少ないと、導電性皮膜などとされた場合の表面平滑性や透明性に劣るものとなったりする場合や、導電性コーティング剤を基材に塗布する際の、基材との密着性が低下したりする場合がある。 In the conductive coating agent of the present invention, the blending ratio of the coated fibrous copper fine particles and the binder is a volume ratio (A / B) between the volume of the coated fibrous copper fine particles (A) and the volume of the binder (B). It is preferably 1/100 to 5/1, more preferably 1/20 to 1/1. When the coated fibrous copper fine particles are so small that the volume ratio of the coated fibrous copper fine particles and the binder is less than 1/100, the conductive coating agent obtained or the conductive film obtained from the coating agent can conduct electricity. May be low. On the other hand, if the binder is so small that the volume ratio exceeds 5/1, the surface smoothness and transparency of the conductive film may be inferior, or the conductive coating agent may be used as a base material. In some cases, the adhesion with the substrate may be reduced.
　本発明の導電性コーティング剤における固形分（本発明の被覆繊維状銅微粒子、バインダ、及び必要に応じてその他添加剤の固形分の合計）濃度は、導電性や取扱性などのバランスに優れる観点から、１～９９質量％が好ましく、１～５０質量％がより好ましい。 The solid content in the conductive coating agent of the present invention (the total solid content of the coated fibrous copper fine particles of the present invention, a binder, and other additives as required) is a concentration that is excellent in balance between conductivity and handleability. Therefore, 1 to 99% by mass is preferable, and 1 to 50% by mass is more preferable.
　また、本発明の導電性コーティング剤の２０℃における粘度は、取扱性や基材への塗布容易性などに優れる観点から、０．５～１００ｍＰａ・ｓであることが好ましく、１～５０ｍＰａ・ｓであることがより好ましい。 In addition, the viscosity at 20 ° C. of the conductive coating agent of the present invention is preferably 0.5 to 100 mPa · s, preferably 1 to 50 mPa · s from the viewpoint of excellent handling properties and ease of application to a substrate. It is more preferable that
　本発明の導電性コーティング剤には、本発明の効果を損なわない範囲において、必要に応じて、アルデヒド系、エポキシ系、メラミン系、イソシアネート系などの架橋剤が用いられてもよい。 In the conductive coating agent of the present invention, an aldehyde-based, epoxy-based, melamine-based, or isocyanate-based cross-linking agent may be used as necessary within the range not impairing the effects of the present invention.
　本発明の導電性コーティング剤を製膜することにより、本発明の導電性皮膜を得ることができる。さらに、該導電性皮膜を基材上に形成することにより、本発明の導電性フィルムを得ることができる。本発明の導電性皮膜及び導電性フィルムは、透明性及び導電性のいずれにも優れるものである。 The conductive film of the present invention can be obtained by forming the conductive coating agent of the present invention into a film. Furthermore, the conductive film of the present invention can be obtained by forming the conductive film on a substrate. The conductive film and conductive film of the present invention are excellent in both transparency and conductivity.
　導電性皮膜の形成方法としては、本発明の導電性コーティング剤を、プラスチックフィルムなどの基材表面上に塗布して、次いで乾燥した後、必要に応じ硬化させることにより膜形成するという、いわゆる液相成膜法が挙げられる。塗布方法としては、ロールコート法、バーコート法、ディップコーティング法、スピンコーティング法、キャスティング法、ダイコート法、ブレードコート法、グラビアコート法、カーテンコート法、スプレーコート法、ドクターコート法などの方法を用いることができる。 As a method for forming a conductive film, the conductive coating agent of the present invention is applied on the surface of a substrate such as a plastic film, then dried, and then cured as necessary to form a film. A phase film forming method can be mentioned. Application methods include roll coating, bar coating, dip coating, spin coating, casting, die coating, blade coating, gravure coating, curtain coating, spray coating, and doctor coating. Can be used.
　導電性皮膜の膜厚みは、実用性などの観点から、例えば、０．１～１０μｍ程度であってもよい。 The film thickness of the conductive film may be, for example, about 0.1 to 10 μm from the viewpoint of practicality.
　また、本発明の被覆繊維状銅微粒子を含有する導電性皮膜あるいは導電性フィルムを形成するためには、本発明の被覆繊維状銅微粒子のみをプラスチックフィルムなどの基材表面上に塗布し、必要に応じ、該塗布された被覆繊維状銅微粒子を保護するための被覆層を形成する方法を用いることもできる。 Further, in order to form a conductive film or conductive film containing the coated fibrous copper fine particles of the present invention, only the coated fibrous copper fine particles of the present invention are applied on the surface of a substrate such as a plastic film and necessary. Depending on the method, a method of forming a coating layer for protecting the coated coated copper fine particles can also be used.
  以下、実施例によって本発明を具体的に説明する。なお、本発明は、これらの実施例によって限定されるものではない。 Hereinafter, the present invention will be described specifically by way of examples. In addition, this invention is not limited by these Examples.
　実施例にて得られた被覆繊維状銅微粒子、並びに、比較例にて用いられた未被覆の繊維状銅微粒子又は繊維状銀微粒子に関する評価方法あるいは測定方法は以下の通りである。
１．溶存酸素と反応しない還元性化合物の評価
　上記式（１）［つまり、Ａ＝（溶存酸素濃度２）／（溶存酸素濃度１）］による還元性化合物と溶存酸素の反応についての判断基準に基づき、実施例及び比較例にて用いられた還元性化合物の溶存酸素との反応性について評価した。
　なお、溶存酸素濃度１は、上記のようにして測定された、アルカリ水溶液中の溶存酸素濃度である。溶存酸素濃度２は、上記のようにして測定された、還元性化合物の添加後から１０分後の水溶液中の溶存酸素濃度である。 The evaluation method or measurement method regarding the coated fibrous copper fine particles obtained in the examples and the uncoated fibrous copper fine particles or fibrous silver fine particles used in the comparative examples is as follows.
1. Evaluation of Reducing Compound that Does Not React with Dissolved Oxygen Based on the above criteria (1) [that is, A = (dissolved oxygen concentration 2) / (dissolved oxygen concentration 1)], based on the judgment criteria for the reaction between the reducing compound and dissolved oxygen, The reactivity of the reducing compounds used in Examples and Comparative Examples with dissolved oxygen was evaluated.
The dissolved oxygen concentration 1 is the dissolved oxygen concentration in the alkaline aqueous solution measured as described above. The dissolved oxygen concentration 2 is the dissolved oxygen concentration in the aqueous solution 10 minutes after the addition of the reducing compound, measured as described above.
２．アルカリ水溶液中の溶存酸素濃度
　溶存酸素計「ＤＯ－５５０９」（Ｌｕｔｒｏｎ社製）を用いて測定した。 2. Dissolved oxygen concentration in alkaline aqueous solution Measured using a dissolved oxygen meter “DO-5509” (manufactured by Lutron).
３．繊維状銅微粒子及び銅粒状体の、短径及び長さ
　繊維状銅微粒子の集合体を準備し、該繊維状銅微粒子同士が密着しすぎないようにするため、超音波分散装置を用いて軽く解した。その後、デジタルマイクロスコープ（キーエンス社製、「ＶＨＸ－１０００、ＶＨＸ－Ｄ５００／５１０」）を用いて観察した。集合体の中から１００本の繊維状銅微粒子を選択し、それぞれの繊維状銅微粒子及び銅粒状体の、短径及び長さを測定し、それらの平均値を短径及び長さとした。 3. Prepare a collection of fibrous copper fine particles and short diameters and lengths of fibrous copper fine particles and copper particulates, and use an ultrasonic dispersing device to prevent the fibrous copper fine particles from being too close to each other. I understood. Thereafter, observation was performed using a digital microscope (manufactured by Keyence Corporation, “VHX-1000, VHX-D500 / 510”). 100 fibrous copper fine particles were selected from the aggregate, the short diameter and the length of each fibrous copper fine particle and the copper granular body were measured, and the average values thereof were defined as the short diameter and the length.
４．繊維状銅微粒子及び銅粒状体のアスペクト比
　上記３．にて求めた長さを短径で除することにより、繊維状銅微粒子及び銅粒状体のアスペクト比を算出した。 4). 2. Aspect ratio of fibrous copper fine particles and copper granules The aspect ratio of the fibrous copper fine particles and the copper granules was calculated by dividing the length obtained in (1) by the minor axis.
５．繊維状銅微粒子１本あたりの銅粒状体の個数
　繊維状銅微粒子の集合体を準備し、該繊維状銅微粒子同士が密着しすぎないようにするため、超音波分散装置を用いて軽く解した。その後、デジタルマイクロスコープ（キーエンス社製、「ＶＨＸ－１０００、ＶＨＸ－Ｄ５００／５１０」）を用いて観察した。集合体の中から１００本の繊維状銅微粒子を選択し、該繊維状銅微粒子における銅粒状体の個数をカウントし、銅粒状体の個数を繊維状銅微粒子の本数（１００本）で除することにより、繊維状銅微粒子１本あたりの銅粒状体の個数を算出した。 5. Number of copper particles per fibrous copper fine particle Prepared an aggregate of fibrous copper fine particles, and in order to prevent the fibrous copper fine particles from sticking too much together, it was lightly solved using an ultrasonic dispersing device. . Thereafter, observation was performed using a digital microscope (manufactured by Keyence Corporation, “VHX-1000, VHX-D500 / 510”). 100 fibrous copper particles are selected from the aggregate, the number of copper particles in the fibrous copper particles is counted, and the number of copper particles is divided by the number of fibrous copper particles (100). Thus, the number of copper particles per one fibrous copper fine particle was calculated.
６．繊維状銅微粒子に対する金属の被覆量
　実施例にて得られた被覆繊維状銅微粒子をガラスビーカーに採取し、硝酸で溶解、希釈したものを測定溶液とした。この測定溶液に対して、ＩＣＰ（日本ジャーレルアッシュ社製）による定量評価を実施した。そして、定量された各金属（つまり、銅及び銅以外の金属）の含有量比から、繊維状銅微粒子に対する金属の被覆量を算出した。なお、本明細書の実施例においては、銅以外の金属として銀を用いているため、金属の被覆量とは銀の被覆量をいうものである。 6). Coating amount of metal on fibrous copper fine particles The coated fibrous copper fine particles obtained in the examples were collected in a glass beaker, dissolved and diluted with nitric acid, and used as a measurement solution. The measurement solution was subjected to quantitative evaluation by ICP (manufactured by Nippon Jarrell Ash). And the metal coating amount with respect to fibrous copper microparticles was computed from the content ratio of each metal (namely, metals other than copper and copper) quantified. In addition, in the Example of this specification, since silver is used as metals other than copper, the metal coating amount means the silver coating amount.
７．被覆繊維状銅微粒子、及び未被覆の繊維状銅微粒子の安定性
　実施例にて得られた被覆繊維状銅微粒子、および比較例にて用いられた未被覆の繊維状銅微粒子を７日間水に浸漬し、室温にて静置した。その後、リガク社製の「ＲＩＮＴ－ＴＴＲ　ＩＩＩ」を用いたＸ線回折法により、被覆繊維状銅微粒子あるいは未被覆の繊維状銅微粒子の表面における、銅、及び銀以外の物質（例えば、酸化銅など）のピークの有無を確認することにより、該物質の検出をおこなった。以下の基準で、安定性の評価をおこなった。
　○：銅、及び銀以外の物質が検出されなかった。
　×：銅、及び銀以外の物質が検出された。 7. Stability of coated fibrous copper fine particles and uncoated fibrous copper fine particles The coated fibrous copper fine particles obtained in the examples and the uncoated fibrous copper fine particles used in the comparative examples were in water for 7 days. Immersion and let stand at room temperature. Thereafter, substances other than copper and silver (for example, copper oxide) on the surface of coated fibrous copper fine particles or uncoated fibrous copper fine particles are obtained by X-ray diffraction using “RINT-TTR III” manufactured by Rigaku Corporation. Etc.), the substance was detected. The stability was evaluated according to the following criteria.
○: No substance other than copper and silver was detected.
X: Substances other than copper and silver were detected.
８．被覆繊維状銅微粒子の体積固有抵抗、及び抵抗値変化（単位：Ω・ｃｍ）
　実施例にて得られた被覆繊維状銅微粒子、あるいは比較例にて用いられた未被覆の繊維状銅微粒子をアスコルビン酸水溶液（１０質量％）中に分散させた後、窒素による加圧ろ過（フィルター：孔径が１μｍであるＰＴＦＥメンブレンフィルター、アドバンテック社製）によって回収し、フィルター上に微粒子がシート状に積層されたサンプルを作製した。得られたサンプルを６０℃に設定した乾燥機で３０分間常圧乾燥したのち、１時間の減圧乾燥処理をおこなった。抵抗率計（ダイアインスツルメンツ社製、ロレスタＡＰ、ＭＣＰ－Ｔ４００）を用いて、シート状に積層された各微粒子の体積固有抵抗を測定した。 8). Volume specific resistance and resistance value change of coated fibrous copper fine particles (unit: Ω · cm)
The coated fibrous copper fine particles obtained in the examples or the uncoated fibrous copper fine particles used in the comparative examples are dispersed in an ascorbic acid aqueous solution (10% by mass), and then pressure filtration with nitrogen ( Filter: PTFE membrane filter having a pore size of 1 μm (manufactured by Advantech Co., Ltd.), and a sample in which fine particles were laminated in a sheet form on the filter was prepared. The obtained sample was dried at atmospheric pressure for 30 minutes with a drier set at 60 ° C., and then subjected to a vacuum drying treatment for 1 hour. Using a resistivity meter (manufactured by Dia Instruments, Loresta AP, MCP-T400), the volume resistivity of each fine particle laminated in a sheet shape was measured.
　次にサンプルを乾燥機内、空気雰囲気下において１８０℃、１時間の加熱処理をおこなった後、上記と同様に、シート状に積層された各微粒子の体積固有抵抗を測定し、加熱処理による抵抗値の変化を評価した。 Next, after heat-treating the sample in a dryer in an air atmosphere at 180 ° C. for 1 hour, in the same manner as described above, the volume specific resistance of each fine particle laminated in a sheet shape is measured, and the resistance value by the heat treatment is measured. Was evaluated for changes.
（未被覆の繊維状銅微粒子の製造例１）
　３００ｍＬの三口フラスコ内にて、アルカリ性化合物としての１０８．０ｇの水酸化ナトリウム（ナカライ社製）を、純水（２７℃における溶存酸素濃度：８．７ｍｇ／Ｌ）１８０．０ｇに溶解した。次いで、銅イオンを生成させるための銅塩としての０．１５ｇの硝酸銅三水和物（ナカライ社製）を６．２ｇの純水で溶解させた水溶液、及び含窒素化合物としての０．８１ｇのエチレンジアミン（ナカライ社製）を添加し、２００ｒｐｍで撹拌をおこない、均一な青色の水溶液を調製した。ここで、該水溶液中における水酸化物イオンと銅イオンのモル比は４５００／１とした。 (Production Example 1 of Uncoated Fibrous Copper Fine Particles)
In a 300 mL three-necked flask, 108.0 g of sodium hydroxide (manufactured by Nacalai Co., Ltd.) as an alkaline compound was dissolved in 180.0 g of pure water (dissolved oxygen concentration at 27 ° C .: 8.7 mg / L). Next, an aqueous solution prepared by dissolving 0.15 g of copper nitrate trihydrate (manufactured by Nacalai Co., Ltd.) as a copper salt for generating copper ions in 6.2 g of pure water, and 0.81 g as a nitrogen-containing compound Of ethylenediamine (manufactured by Nacalai Co., Ltd.) was added and stirred at 200 rpm to prepare a uniform blue aqueous solution. Here, the molar ratio of hydroxide ions to copper ions in the aqueous solution was 4500/1.
　この水溶液に、還元性化合物としてのアスコルビン酸（ナカライ社製、上記の数値Ａ：０．８８）の水溶液（４．４質量％）１．２ｇを加え、２００ｒｐｍで撹拌を継続したまま、三口フラスコを８０℃の湯浴に浸漬した。液の色は青色から徐々に薄くなり、３０分後にはほぼ無色透明にまで変化した。 To this aqueous solution, 1.2 g of an aqueous solution (4.4% by mass) of ascorbic acid as a reducing compound (manufactured by Nacalai Co., Ltd., the above numerical value A: 0.88) was added, and the stirring was continued at 200 rpm. Was immersed in an 80 ° C. hot water bath. The color of the liquid gradually faded from blue and changed to almost colorless and transparent after 30 minutes.
　さらに３０分経過後、還元性化合物としてのアスコルビン酸水溶液（４．４質量％）４．８ｇを添加し、約１分間撹拌を継続した。その後、撹拌を停止し、三口フラスコを湯浴から引き上げたところ、冷却過程において繊維状銅微粒子が析出したことを目視で確認した。なお、反応中、三口フラスコ内は空気が充満された状態であった。 Further, after 30 minutes, 4.8 g of an ascorbic acid aqueous solution (4.4% by mass) as a reducing compound was added, and stirring was continued for about 1 minute. Thereafter, stirring was stopped and the three-necked flask was lifted from the hot water bath, and it was visually confirmed that fibrous copper fine particles were deposited in the cooling process. During the reaction, the inside of the three-necked flask was filled with air.
　析出した繊維状銅微粒子を、窒素による加圧ろ過（孔径が１μｍであるＰＴＦＥメンブレンフィルター、アドバンテック社製）によって回収し、アルコルビン酸水溶液（１０質量％）で１回、純水で３回洗浄後、５０℃に設定した乾燥機内で乾燥した。これを「未被覆繊維状銅粒子１」とした。この未被覆繊維状銅微粒子１に対して、上記の３．、４．および５．の評価をおこなった。評価結果を表１に示す。該評価結果は実施例１～４および比較例１における、繊維状銅微粒子の形状の項目にて示されている。 The precipitated fibrous copper fine particles are recovered by pressure filtration with nitrogen (PTFE membrane filter having a pore size of 1 μm, manufactured by Advantech), and washed once with an aqueous corcorbic acid solution (10% by mass) and three times with pure water. And drying in a dryer set at 50 ° C. This was designated as “uncoated fibrous copper particles 1”. With respect to the uncoated fibrous copper fine particles 1, the above 3. 4. And 5. Was evaluated. The evaluation results are shown in Table 1. The evaluation results are shown in the item of the shape of the fibrous copper fine particles in Examples 1 to 4 and Comparative Example 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（未被覆の繊維状銅微粒子の製造例２）
　３００ｍＬ三口フラスコ内にて、アルカリ性化合物としての１０８．０ｇの水酸化ナトリウム（ナカライ社製）を、純水（２７℃における溶存酸素濃度：８．７ｍｇ／Ｌ）１８０．０ｇに溶解した。次いで、銅イオンを生成させるための銅塩としての０．２２ｇの硝酸銅三水和物（ナカライ社製）を９．２ｇの純水で溶解させた水溶液、及び含窒素化合物としてのエチレンジアミン（ナカライ社製）１．２ｇを添加して、２００ｒｐｍで撹拌をおこない、均一な青色の水溶液を調製した。ここで、水溶液中における水酸化物イオンと銅イオンのモル比は３０００／１とした。 (Production Example 2 of Uncoated Fibrous Copper Fine Particles)
In a 300 mL three-necked flask, 108.0 g of sodium hydroxide (manufactured by Nacalai Co., Ltd.) as an alkaline compound was dissolved in 180.0 g of pure water (dissolved oxygen concentration at 27 ° C .: 8.7 mg / L). Next, an aqueous solution in which 0.22 g of copper nitrate trihydrate (manufactured by Nacalai Co., Ltd.) as a copper salt for generating copper ions was dissolved in 9.2 g of pure water, and ethylenediamine (Nacalai) as a nitrogen-containing compound were prepared. 1.2 g) was added and stirred at 200 rpm to prepare a uniform blue aqueous solution. Here, the molar ratio of hydroxide ions to copper ions in the aqueous solution was set to 3000/1.
　この溶液に、還元性化合物としてのヒドラジン一水和物（和光純薬工業社製、上記の数値Ａ：０．０５）水溶液（５５質量％）０．３４ｇを加え、２００ｒｐｍで撹拌を継続したまま、三口フラスコを８０℃の湯浴に浸漬した。すぐに液の色が青色から無色透明に変化し、析出物が発生した。次いで、６０分後に三口フラスコを湯浴から引き上げた。なお、反応中、三口フラスコ内は空気が充満された状態であった。得られた析出物を実施例１と同様の方法で回収し、これを「未被覆繊維状銅微粒子２」とした。この未被覆繊維状銅微粒子２に対して、上記の３．、４．および５．の評価をおこなった。評価結果を表１に示す。該評価結果は実施例５および比較例２における、繊維状銅微粒子の形状の項目にて示されている。 To this solution, 0.34 g of an aqueous solution (55% by mass) of hydrazine monohydrate (manufactured by Wako Pure Chemical Industries, Ltd., the above numerical value A: 0.05) as a reducing compound was added, and stirring was continued at 200 rpm. The three-necked flask was immersed in an 80 ° C. hot water bath. Immediately, the color of the liquid changed from blue to colorless and transparent, and a precipitate was generated. Then, after 60 minutes, the three-necked flask was lifted from the hot water bath. During the reaction, the inside of the three-necked flask was filled with air. The obtained precipitate was recovered in the same manner as in Example 1, and this was designated as “uncoated fibrous copper fine particles 2”. With respect to the uncoated fibrous copper fine particles 2, the above 3. 4. And 5. Was evaluated. The evaluation results are shown in Table 1. The evaluation results are shown in the item of the shape of the fibrous copper fine particles in Example 5 and Comparative Example 2.
（実施例１）
　スターラーチップを入れたプラスチック容器中に、「未被覆繊維状銅粒子１」０．０１ｇと、アスコルビン酸水溶液（１０質量％）１８ｇとを添加し懸濁液を作製した。該懸濁液を、室温にて７００ｒｐｍで撹拌しながら、置換型無電解銀メッキ用プレディップ液（四国化成工業社製、「ＳＳＰ－７００Ｐ」）２ｇを添加し、添加後５分間撹拌を継続した。さらに、７００ｒｐｍでの撹拌を継続したまま、置換型無電解銀メッキ液（四国化成工業社製、「ＳＳＰ－７００Ｍ」）０．５ｇとイオン交換水１９．５ｇを混合した溶液を５分間かけて滴下添加したところ、この懸濁液の色調が赤褐色から薄茶色に変化した。 Example 1
In a plastic container containing a stirrer chip, 0.01 g of “uncoated fibrous copper particles 1” and 18 g of an ascorbic acid aqueous solution (10 mass%) were added to prepare a suspension. While stirring the suspension at room temperature at 700 rpm, 2 g of a pre-dip solution for substitution type electroless silver plating (Shikoku Kasei Kogyo Co., Ltd., “SSP-700P”) was added, and stirring was continued for 5 minutes after the addition. did. Further, while continuing stirring at 700 rpm, a solution obtained by mixing 0.5 g of a substitution type electroless silver plating solution (“SSP-700M” manufactured by Shikoku Kasei Kogyo Co., Ltd.) and 19.5 g of ion-exchanged water over 5 minutes. When added dropwise, the color of the suspension changed from reddish brown to light brown.
　この懸濁液に対して、窒素による加圧ろ過処理（フィルター：孔径が１μｍであるＰＴＦＥメンブレンフィルター、アドバンテック社製）をおこない、イオン交換水を通して洗浄することにより、フィルター上において、微粒子がシート状に積層されたサンプルを作製した。このサンプルを６０℃に設定した乾燥機内で乾燥することにより、銀で被覆された繊維状銅微粒子が、フィルター上に堆積した状態で得られた。得られた被覆繊維状銅微粒子に対して、上記の６.、７.および８．の評価をおこなった。評価結果を表１に示す。 The suspension is subjected to pressure filtration with nitrogen (filter: PTFE membrane filter with a pore size of 1 μm, manufactured by Advantech) and washed with ion-exchanged water, whereby fine particles are formed in a sheet form on the filter. The sample laminated | stacked on was produced. The sample was dried in a drier set at 60 ° C., and thus, fibrous copper fine particles coated with silver were obtained in a state of being deposited on the filter. With respect to the obtained coated fibrous copper fine particles, the above-mentioned 6., 7. and 8. Was evaluated. The evaluation results are shown in Table 1.
（実施例２）
　実施例１において、置換型無電解銀メッキ液（四国化成工業社製、「ＳＳＰ－７００Ｍ」）０．５ｇとイオン交換水１９．５ｇを混合した溶液を、それぞれの混合量を１ｇと１９ｇとに変更した以外は、実施例１と同様の方法により、銀で被覆された被覆繊維状銅微粒子を得た。得られた被覆繊維状銅微粒子に対して、実施例１と同様の評価をおこなった。評価結果を表１に示す。 (Example 2)
In Example 1, a solution obtained by mixing 0.5 g of a substitution type electroless silver plating solution (“SSP-700M” manufactured by Shikoku Kasei Kogyo Co., Ltd.) and 19.5 g of ion-exchanged water was mixed into 1 g and 19 g, respectively. The coated fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1 except that the above was changed. Evaluation similar to Example 1 was performed with respect to the obtained coated fibrous copper fine particles. The evaluation results are shown in Table 1.
（実施例３）
　実施例１において、置換型無電解銀メッキ液（四国化成工業社製、「ＳＳＰ－７００Ｍ」）０．５ｇとイオン交換水１９．５ｇを混合した溶液を、それぞれの混合量を０．２ｇと１９．８ｇに変更した以外は、実施例１と同様の方法により、銀で被覆された被覆繊維状銅微粒子を得た。得られた被覆繊維状銅微粒子に対して、実施例１と同様の評価をおこなった。評価結果を表１に示す。 (Example 3)
In Example 1, a solution obtained by mixing 0.5 g of a substitutional electroless silver plating solution (“SSP-700M”, manufactured by Shikoku Kasei Kogyo Co., Ltd.) and 19.5 g of ion-exchanged water, Coated fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1 except that the amount was changed to 19.8 g. Evaluation similar to Example 1 was performed with respect to the obtained coated fibrous copper fine particles. The evaluation results are shown in Table 1.
（実施例４）
　実施例１において、置換型無電解銀メッキ液（四国化成工業社製、「ＳＳＰ－７００Ｍ」）０．５ｇとイオン交換水１９．５ｇを混合した溶液を、それぞれの混合量を０．１ｇと１９．９ｇに変更した以外は、実施例１と同様の方法により、銀で被覆された繊維状銅微粒子を得た。得られた被覆繊維状銅微粒子に対して、実施例１と同様の評価をおこなった。評価結果を表１に示す。 Example 4
In Example 1, a solution obtained by mixing 0.5 g of a substitution-type electroless silver plating solution (“SSP-700M” manufactured by Shikoku Kasei Kogyo Co., Ltd.) and 19.5 g of ion-exchanged water was used. Except for changing to 19.9 g, fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1. Evaluation similar to Example 1 was performed with respect to the obtained coated fibrous copper fine particles. The evaluation results are shown in Table 1.
（実施例５）
　「未被覆繊維状銅粒子１」の代わりに「未被覆繊維状銅粒子２」を用いた以外は、実施例１と同様の方法により、銀で被覆された繊維状銅微粒子を得た。得られた被覆繊維状銅微粒子に対し、体積固有抵抗以外の項目について、実施例１と同様の評価をおこなった。評価結果を表１に示す。 (Example 5)
Except for using “uncoated fibrous copper particles 2” instead of “uncoated fibrous copper particles 1”, fibrous copper fine particles coated with silver were obtained in the same manner as in Example 1. Evaluation similar to Example 1 was performed about items other than volume specific resistance with respect to the obtained coated fibrous copper fine particle. The evaluation results are shown in Table 1.
（比較例１）
　「未被覆繊維状銅粒子１」に対して、金属による被覆処理をおこなわずに、実施例１と同様の評価をおこなった。評価結果を表１に示す。 (Comparative Example 1)
The same evaluation as in Example 1 was performed on the “uncoated fibrous copper particles 1” without performing metal coating. The evaluation results are shown in Table 1.
（比較例２）
　「未被覆繊維状銅粒子２」に対して、金属による被覆処理をおこなわずに、体積固有抵抗以外の項目について、実施例１と同様の評価をおこなった。評価結果を表１に示す。 (Comparative Example 2)
The same evaluation as in Example 1 was performed on items other than the volume resistivity without performing a coating treatment with metal on the “uncoated fibrous copper particles 2”. The evaluation results are shown in Table 1.
（比較例３）
　繊維状銀微粒子としての短径が０．１μｍかつ長さが３０μｍであるシルバーナノワイヤー分散液６ｇ（Ａｌｄｒｉｃｈ社製、品番７３９４４８、シルバーナノワイヤーが０．５質量％の割合でイソプロパノール中に分散している分散液）に対して、窒素による加圧ろ過処理（フィルター：孔径が１μｍであるＰＴＦＥメンブレンフィルター、アドバンテック社製）をおこない、フィルター上において繊維状銀微粒子がシート状に積層されたサンプルを作製した。このサンプルを６０℃に設定した乾燥機で３０分間常圧乾燥したのち、１時間の減圧乾燥処理をおこなった。 (Comparative Example 3)
6 g of silver nanowire dispersion liquid having a minor axis of 0.1 μm and a length of 30 μm as fibrous silver fine particles (manufactured by Aldrich, product number 739448, silver nanowire is dispersed in isopropanol at a ratio of 0.5 mass%. The dispersion liquid is subjected to pressure filtration with nitrogen (filter: PTFE membrane filter having a pore size of 1 μm, manufactured by Advantech), and a sample in which fibrous silver fine particles are laminated in a sheet form on the filter is obtained. Produced. This sample was dried at atmospheric pressure for 30 minutes with a drier set at 60 ° C., and then subjected to a vacuum drying treatment for 1 hour.
　減圧乾燥処理後のサンプルに対して、抵抗率計（ダイアインスツルメンツ社製、ロレスタＡＰ、ＭＣＰ－Ｔ４００）を用いて、体積固有抵抗を測定した。初期の体積固有抵抗値は５．７×１０－５（Ω・ｃｍ）であった。その後、１８０℃、１時間の加熱処理をおこなった後の体積固有抵抗値は５．０×１０－５（Ω・ｃｍ）であった。 The volume resistivity was measured for the sample after the drying under reduced pressure using a resistivity meter (Dore Instruments, Loresta AP, MCP-T400). The initial volume resistivity value was 5.7 × 10 −5 (Ω · cm). Thereafter, the volume resistivity value after heat treatment at 180 ° C. for 1 hour was 5.0 × 10 −5 (Ω · cm).
　実施例１～５にて得られた被覆繊維状銅微粒子は、長さが１μｍ以上、アスペクト比が１０以上である繊維状銅微粒子から簡便に得られたものであり、安定性に優れたものであった。 The coated fibrous copper fine particles obtained in Examples 1 to 5 were simply obtained from fibrous copper fine particles having a length of 1 μm or more and an aspect ratio of 10 or more, and excellent in stability. Met.
　特に、実施例１～４にて得られた被覆繊維状銅微粒子は、短径が１μｍ以下であってアスペクト比が非常に大きく、短径が０．３μｍ以上かつアスペクト比が１．５以下の銅粒状体の存在割合が少ない繊維状銅微粒子を、銀にて被覆して得られたものであった。そのため、未被覆の繊維状銅微粒子（比較例１）と比べると、体積固有抵抗が低い値となり、すなわち良好な導電性を示すものであった。その導電性は、繊維状銀微粒子（比較例３）とほぼ同等のものであり、銀のみからなる繊維状微粒子と比較しても遜色のないものであった。 In particular, the coated fibrous copper fine particles obtained in Examples 1 to 4 have a minor axis of 1 μm or less and an extremely large aspect ratio, a minor axis of 0.3 μm or more and an aspect ratio of 1.5 or less. It was obtained by coating fibrous copper fine particles with a small proportion of copper particles with silver. Therefore, compared with uncoated fibrous copper fine particles (Comparative Example 1), the volume specific resistance was a low value, that is, good conductivity was exhibited. The conductivity was almost the same as that of the fibrous silver fine particles (Comparative Example 3), and was comparable to the fibrous fine particles consisting of only silver.
　一方、比較例１および２においては、表面を銅以外の金属で被覆していない繊維状銅微粒子を用いて評価をおこなった。この繊維状銅微粒子は、安定性において良好な特性を有するものではなかった。 On the other hand, in Comparative Examples 1 and 2, the evaluation was performed using fibrous copper fine particles whose surface was not coated with a metal other than copper. The fibrous copper fine particles did not have good characteristics in stability.
　また、実施例１～４は、長さが１μｍ以上、アスペクト比が１０以上である繊維状銅微粒子への銀被覆量を制御できることを、初めて示すものである。実施例１～４における銀被覆繊維状銅微粒子の加熱処理による体積固有抵抗値の変化は、比較例３で示した繊維状銀微粒子と同様にほとんど見られず、良好な特性であった。一方、比較例１は、表面を銅以外の金属で被覆していない繊維状銅微粒子であったため、加熱処理後の体積固有抵抗が著しく増大し、導電性が悪化した。 Further, Examples 1 to 4 show for the first time that the silver coating amount on the fibrous copper fine particles having a length of 1 μm or more and an aspect ratio of 10 or more can be controlled. The change in the volume resistivity value due to the heat treatment of the silver-coated fibrous copper fine particles in Examples 1 to 4 was almost the same as that of the fibrous silver fine particles shown in Comparative Example 3, and was a good characteristic. On the other hand, since Comparative Example 1 was a fibrous copper fine particle whose surface was not coated with a metal other than copper, the volume resistivity after the heat treatment was remarkably increased and the conductivity was deteriorated.
　本発明の被覆繊維状銅微粒子を用いることにより、優れた導電性と透明性とを兼ね備えた導電性コーティング剤、導電性皮膜及び導電性フィルムを得ることができるため、非常に有用である。
 
  By using the coated fibrous copper fine particles of the present invention, a conductive coating agent, a conductive film and a conductive film having both excellent conductivity and transparency can be obtained, which is very useful.

Claims (5)

  1. 　繊維状銅微粒子の少なくとも一部が銅以外の金属で被覆された被覆繊維状銅微粒子であって、該繊維状銅微粒子の長さが１μｍ以上であり、かつアスペクト比が１０以上であることを特徴とする被覆繊維状銅微粒子。 It is a coated fibrous copper fine particle in which at least a part of the fibrous copper fine particle is coated with a metal other than copper, the length of the fibrous copper fine particle is 1 μm or more, and the aspect ratio is 10 or more. Features of coated fibrous copper fine particles.
  2. 　繊維状銅微粒子の短径が１μｍ以下であり、該繊維状銅微粒子における、短径が０．３μｍ以上かつアスペクト比が１．５以下である銅粒状体の存在割合が繊維状銅微粒子１本あたり０．１個以下であることを特徴とする請求項１に記載の被覆繊維状銅微粒子。 The short diameter of the fibrous copper fine particles is 1 μm or less, and the proportion of copper particles having a short diameter of 0.3 μm or more and an aspect ratio of 1.5 or less in the fibrous copper fine particles is one fibrous copper fine particle. The coated fibrous copper fine particles according to claim 1, wherein the number is 0.1 or less.
  3. 　請求項１又は２に記載の被覆繊維状銅微粒子を含有することを特徴とする導電性コーティング剤。 A conductive coating agent comprising the coated fibrous copper fine particles according to claim 1 or 2.
  4. 　請求項１又は２に記載の被覆繊維状銅微粒子を含有することを特徴とする導電性皮膜。 A conductive film comprising the coated fibrous copper fine particles according to claim 1 or 2.
  5. 　請求項４に記載の導電性皮膜を基材上に有することを特徴とする導電性フィルム。
          A conductive film comprising the conductive film according to claim 4 on a substrate.
PCT/JP2012/065187 2011-06-14 2012-06-14 Coated fibrous copper microparticles, and electrically conductive coating agent and electrically conductive film each containing said coated fibrous copper microparticles WO2012173171A1 (en)

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US14/123,632 US20140120360A1 (en) 2011-06-14 2012-06-14 Coated fibrous copper microparticles, and electrically conductive coating agent and electrically conductive film each containing said coated fibrous copper microparticles
CN201280024258.4A CN103547396B (en) 2011-06-14 2012-06-14 It is coated to threadiness copper microgranule and the electric conductivity smears and the conductive film that comprise this coating threadiness copper microgranule

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CN103547396A (en) 2014-01-29
CN103547396B (en) 2016-09-28

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