JP4616599B2 - Fluid composition, electrode formed using the same, and wiring pattern - Google Patents

Description

  The present invention relates to a fluid composition containing metal colloid particles, an electrode formed using the fluid composition, and a wiring pattern.

  Metal particles having an average particle diameter of about 1 to 100 nm are called metal colloid particles, and have a very high conductivity and a property of transmitting visible light. For example, coating agents and paints containing metal colloid particles By applying a fluid composition such as CRT, it is applied to electromagnetic wave shielding of transparent members such as cathode ray tubes and liquid crystal displays. In recent years, a technique for forming a fine electrode by using a fluid composition such as paste, ink, paint, or the like containing colloidal particles such as silver and copper has been proposed. This is because the flowable composition is applied with a circuit or electrode pattern on the substrate by a method such as screen printing or ink jet printing, and then heated to melt the metal colloidal particles. It is being applied to the manufacture of For example, a technique is known in which metal colloidal particles are coated with an organic compound containing a functional group having chemical adsorption properties, and wiring is formed using a dispersion of the metal colloidal particles (see Patent Document 1).

  Since the metal colloidal particles are fine particles, they have a large surface energy and are easy to agglomerate. Therefore, a surface protective agent called a protective colloid is usually applied to the surface of the metal colloidal particles and dispersed due to its steric hindrance effect. Stabilized. Also in the technique described in Patent Document 1, an organic compound containing a functional group having a chemical adsorption property acts as a protective colloid.

WO01 / 070435 pamphlet

  In order to suppress the heat shrinkage of the coated material as much as possible, the flowable composition generally does not use a binder and contains metal colloid particles in a high concentration. Since the fluid composition having such a composition has a high concentration, the inter-particle distance of the metal colloid particles is small, the inter-particle interaction works strongly, and it is difficult to suppress the interaction even by the protective colloid. Since the stabilizing effect due to the adsorption of the binder cannot be expected as in the case of paints and inks, the dispersion stability tends to be impaired. For this reason, the dispersion stability is good due to the action of the protective colloid immediately after the production, but when a long period of time elapses after the production, for example, when stored for a period of 1 to 2 months, a large number of particle masses in which the metal colloid particles have grown abnormally, When this is used, the conductivity is lowered, and particularly, when a fine circuit or electrode pattern is formed on the substrate, a great obstacle such as disconnection of wiring or cross-connection is caused.

  As a result of intensive studies, the present inventors have found that the colloidal metal particles are abnormal due to the addition of the reducing substance in the fluid composition containing the colloidal metal particles at a high concentration and containing substantially no binder. The inventors have found that the generation of grown particle agglomerates can be prevented and that excellent long-term stability can be obtained, and the present invention has been completed.

  That is, the present invention is a mixture of at least metal colloid particles, a dispersion medium, and a reducing substance, and the content of the metal colloid particles is at least 5% by weight, and is reducible with respect to 100 parts by weight of the metal colloid particles. A fluid composition comprising 0.1 to 50 parts by weight of a substance, wherein the electrode or wiring pattern is formed using the fluid composition.

  Even if the fluid composition of the present invention is used after being stored for a long period of time, it is excellent in performance such as conductivity, and it is easy to form a uniform coated material, in particular, formation of fine electrodes such as printed wiring boards and wiring patterns, etc. Available to:

  The present invention relates to a fluid composition such as an ink, a paint, or a paste obtained by mixing at least metal colloid particles, a dispersion medium, and a reducing substance, and a high concentration in which the amount of the metal colloid particles is at least 5% by weight. The amount of the reducing substance is preferably in the range of 0.1 to 50 parts by weight, preferably 0.1 to 100 parts by weight with respect to 100 parts by weight of the metal colloid particles. The range is 3 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, and still more preferably 0.5 to 5 parts by weight. A preferred embodiment is a fluid composition obtained by mixing at least a reducing substance in a dispersion medium containing metal colloid particles, and the compounding amount of the metal colloid particles and the reducing substance is in the above range. The metal colloid particles in the dispersion medium are oxidized over time, making it easier for metal ions to elute from the metal colloid particles, and it is speculated that the eluted metal ions will grow the metal colloid particles and form a particle lump. The In the present invention, by adding a reducing substance, the colloidal metal particles are prevented from being oxidized, thereby preventing the formation of particle lumps and improving the long-term stability of the fluid composition.

  There is no restriction | limiting in particular in the metal colloid particle used by this invention, 1 type may be used and 2 or more types of metal colloid particles may be mixed and used. Moreover, there is no restriction | limiting in particular also in the metal which comprises a metal colloid particle, It may be comprised by 1 type of metals, or may be comprised by the alloy of 2 or more types of metals. The metal constituting the metal colloidal particles is at least one selected from the group consisting of Group VIII (iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum) and Group IB (copper, silver, gold). If it is a seed, it is preferable because it has high conductivity, and gold, silver, platinum, palladium, and copper are particularly preferable because of high conductivity, and in order to use it as a fluid composition for forming electrodes and wiring patterns, From the balance of cost, silver or copper is particularly preferable. The average particle diameter of the metal colloid particles can be a general one of about 1 to 100 nm, and in order to obtain finer electrodes and wiring patterns, the metal colloid having an average particle diameter in the range of 5 to 50 nm It is preferable to use particles. In order to obtain electrodes and wiring patterns with stable conductivity, it is desirable to form a thick coating by a single coating, so the metal colloid particles are preferably blended at a higher concentration. The content may be 5% by weight or more as described above, more preferably 10% by weight or more, and further preferably 15% by weight or more. The metal colloid particles can also be used as a so-called metal colloid solution in which the metal colloid particles are previously dispersed in a dispersion medium.

  It is preferable that the metal colloid particles have a protective colloid on the surface because the colloidal particles can be dispersed in a more stable state in the dispersion medium by the action of the protective colloid. As the protective colloid, known compounds can be used, and examples thereof include citric acid and derivatives thereof, aniline and derivatives thereof, sulfur compounds and the like, and one or more selected from these can be used. In the present invention, it is preferable to use a sulfur compound having a high protective effect on metal colloidal particles. Specifically, (1) thiols ((a) acid thiols (for example, mercaptoacetic acid, mercaptopropionic acid, thiodipropionic acid) , Mercaptosuccinic acid, thioacetic acid, etc.), (b) aliphatic thiols (for example, methyl mercaptan, ethyl mercaptan, propyl mercaptan, isopropyl mercaptan, n-butyl mercaptan, allyl mercaptan, dimethyl mercaptan, mercaptoethanol, aminoethyl mercaptan, (C) alicyclic thiols (eg, cyclohexyl thiol), (d) aromatic thiols (eg, thiophenol), (2) thioglycols (eg, thiodiethylene glycol, thiodi) Glycolic acid, ethylene Oglycol, etc.), (3) thioamides (eg, thioformamide, etc.), (4) dithiols, (5) thiones, (6) polythiols, (7) thiocarbonates, (8) thioureas, (9) Heterocyclic sulfur compounds, (10) thiazoles, (11) hydrogen sulfide and derivatives thereof may be used, and one or more of these may be used. More preferably, it is at least one selected from mercaptoacetic acid, mercaptopropionic acid, and mercaptoethanol, and the protective colloid is in the range of 0.05 to 1.5 parts by weight with respect to 1 part by weight of the metal colloid particles. If it is applied, a desired protective effect is obtained, which is preferable.

  The metal colloidal particles can be produced by using a known method. For example, (1) a method in which a metal is evaporated in a vacuum and the metal colloid particles are condensed from a gas phase, and (2) a metal compound solution is prepared. A method of adding a reducing agent and precipitating metal colloidal particles from the liquid phase can be used, and the method (2) is a more preferable method because metal colloidal particles can be obtained at low cost. In the method (2), as the metal compound that is a raw material for producing the metal colloid particles, for example, the metal chloride, sulfate, nitrate, carbonate and the like can be used. An organic solvent such as water or alcohol, or a mixed solvent of two or more of these can be used for the medium solution for dissolving the metal compound, and the concentration of the metal compound in the medium solution is within a range in which the metal compound is dissolved. Although there is no particular restriction, it is preferably 5 mmol / liter or more industrially. In order to produce aqueous metal colloidal particles, it is preferable if the metal compound is water-soluble, but even if it is sparingly soluble in water, a compound containing chloride ions, ammonia, etc. that forms a soluble complex with the metal component Can also be used.

  As the reducing agent, known ones can be used, for example, hydrazine, hydrazine reducing agents such as hydrazine compounds such as hydrazine hydrochloride, hydrazine sulfate, hydrazine hydrate, sodium borohydride, sodium sulfite, sodium bisulfite, Metal salts such as sodium thiosulfate, sodium nitrite, sodium hyponitrite, phosphorous acid and sodium phosphite, metal salts such as hypophosphorous acid and sodium hypophosphite, aldehydes, alcohols, amines And saccharides may be used, and one or more of these may be used. The reduction reaction can be carried out at any temperature, and when carried out in an aqueous medium, a temperature in the range of 5 to 90 ° C. is preferred because the reaction can proceed easily. The addition amount of the reducing agent can be appropriately set as long as it can be reduced to a metal, and is preferably 0.2 to 50 mol with respect to 1 mol of the metal compound. If the addition amount is less than 0.2 mol, it is not preferable because the reduction reaction is unlikely to proceed sufficiently, and if it exceeds 50 mol, the dispersion of the generated metal colloid particles tends to become unstable, which is not preferable.

  It is preferable to adjust the pH of the mixed solution of the metal compound and the reducing agent to a range of 8 to 14 because the metal compound is uniformly dispersed in the medium and a reduction reaction is likely to occur. A more preferable pH range is 8 to 13, and 8 to 12 is more preferable. Specifically, for example, after adjusting the pH of the liquid medium containing the metal compound, the metal compound may be reduced, or after mixing the reducing agent, the pH may be adjusted. For pH adjustment, for example, a basic compound such as an alkali metal or alkaline earth metal hydroxide or carbonate such as sodium hydroxide, potassium hydroxide or calcium hydroxide, an ammonium compound such as ammonia, or an amine is used. be able to. The metal colloidal particles thus obtained easily aggregate when the pH of the liquid medium is 5 or less, and can be filtered by a relatively simple operation such as suction filtration or sedimentation separation. A more preferable pH range is 0-5. The colloidal metal colloid particles can be washed by a conventional method, and soluble salts and remaining reducing agent can be sufficiently removed. For pH adjustment, for example, an inorganic compound such as hydrochloric acid, sulfuric acid or nitric acid, or an acidic compound such as organic acid such as formic acid, acetic acid or propionic acid can be used.

  In order to deposit the protective colloid on the surface of the metal colloidal particles, the protective colloid is added to the liquid medium in which the metal colloidal particles are dispersed and mixed or deposited, or the metal colloid is reduced with the metal in the presence of the protective colloid. It is also possible to produce metal colloidal particles on which a protective colloid is deposited by reacting with an agent. The latter method is a preferable method because protective colloid is present during the reduction reaction, and thus highly dispersed metal colloidal particles can be obtained.

The dispersion medium for dispersing the metal colloid particles is appropriately selected according to the affinity with the metal colloid particles to be used. For example, hydrophilic organic solvents such as water, alcohols and ketones, linear hydrocarbons, cyclic Hydrophobic organic solvents such as hydrocarbons and aromatic hydrocarbons can be used, and one type selected from these may be used, or two or more types having compatibility may be used as a mixed dispersion medium. Alternatively, water and a hydrophobic organic solvent can be mixed and used using a hydrophilic organic solvent as a compatibilizing agent. If metal colloidal particles made of a hydrophilic metal such as silver or copper are used, it is preferable to use water or a mixed dispersion medium with a hydrophilic organic solvent mainly composed of water. In this case, water is usually contained in the dispersion medium in an amount of 50% by weight or more, preferably 80% by weight or more. Moreover, since water has a large surface tension, an organic solvent having a relative dielectric constant of 35 or more, preferably 35 to 200, and a boiling point of 100 ° C. or more, preferably 100 to 250 ° C., is added as necessary. Then, it is preferable because surface defects such as wrinkles and shrinkage are not easily generated in the coating during heating and baking, and a uniform and high-density coating is easily obtained. Examples of such organic solvents include N-methylformamide (dielectric constant 190, boiling point 197 ° C.), dimethyl sulfoxide (dielectric constant 45, boiling point 189 ° C.), ethylene glycol (relative dielectric constant 38, boiling point 226 ° C.), 4-butyrolactone. (Relative permittivity 39, boiling point 204 ° C.), acetamide (relative permittivity 65, boiling point 222 ° C.), 1,3-dimethyl-2-imidazolidinone (relative permittivity 38, boiling point 226 ° C.), formamide (relative permittivity 111, boiling point 210 ° C.), N-methylacetamide (relative dielectric constant 175, boiling point 205 ° C.), furfural (relative dielectric constant 40, boiling point 161 ° C.) and the like, and one or more selected from these can be used. . Among them, N-methylformamide (surface tension 38 × 10 ⁻³ N / m) having a surface tension of 50 × 10 ⁻³ N / m or less, dimethyl sulfoxide (surface tension 43 × 10 ⁻³ N / m), ethylene glycol ( Surface tension 48 × 10 ⁻³ N / m), 4-butyrolactone (surface tension 44 × 10 ⁻³ N / m), acetamide (surface tension 39 × 10 ⁻³ N / m), 1,3-dimethyl-2- Imidazolidinone (surface tension 41 × 10 ⁻³ N / m) or the like is more effective and preferable. These organic solvents having a high relative dielectric constant and a high boiling point are preferably contained in the dispersion medium excluding water in the range of 20 to 100% by weight, and more preferably in the range of 40 to 100% by weight.

  The reducing substance blended in the fluid composition of the present invention has a value (noble value) in which the oxidation-reduction potential in the aqueous solution is lower than the oxidation-reduction potential of the metal colloid particles contained in the fluid composition. Known ones having the reducing properties shown are preferred. For example, (1) hydrazine or a hydrate thereof, (2) hydrazine compounds (eg, hydrazine hydrochloride, hydrazine sulfate, etc.), (3) aldehydes ((a) aliphatic aldehydes (eg, formaldehyde, acetaldehyde, propion) Aldehyde, butyraldehyde, isobutyraldehyde, etc.), (b) aromatic aldehydes (eg, benzaldehyde, etc.), (c) heterocyclic aldehydes, etc.), (4) amines ((a) primary amines (eg, Butylamine, ethylamine, propylamine, ethylenediamine, etc.), (b) secondary amines (eg, dibutylamine, diethylamine, dipropylamine, etc.), (c) tertiary amines (eg, tributylamine, triethylamine, tripropyl) Amine) etc.), (5) aminoaldehydes (eg aminoacetoal) Hydride etc.), (6) alkanolamines (eg ethanolamine, diethanolamine, triethanolamine etc.), (7) reducing sugars (eg sucrose, treperth, maltose, lactose etc.), (8) hydrogen compounds (eg (9) low-order inorganic oxygen acids (for example, sulfurous acid, nitrous acid, hyponitrous acid, phosphorous acid, hypophosphorous acid, etc.) and their hydrates (for example, hydrogen sulfite) or the like (For example, alkali metal salts such as sodium) and the like, and one or more selected from these can be used. If the reducing substance is at least one selected from hydrazine or hydrates thereof, aldehydes, amines, amino aldehydes, alkanolamines, and reducing sugars, it is easily decomposed by heating and baking, and conductive in the electrode. It is preferable because there is hardly any remaining component that inhibits the properties, and in particular, one or more selected from hydrazine, hydrates thereof, and aldehydes has a strong reducing power at room temperature or lower and is stable in dispersion. This is more preferable because of its high effect. Among the aldehydes, aliphatic aldehydes and aromatic aldehydes are preferable because of their high effects, and aliphatic aldehydes are particularly preferable. The amount of the reducing substance used is preferably in the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the metal colloid particles. If the amount is less than this range, it is difficult to obtain the desired effect, and the amount is larger than this range. However, it is difficult to obtain further effects and it is not economical. A more preferable range is 0.3 to 30 parts by weight, and a further preferable range is 0.5 to 10 parts by weight.

  The fluid composition of the present invention can be produced by mixing the metal colloidal particles, the dispersion medium, and the reducing substance by a known method, such as stirring and mixing, and wet pulverization and mixing such as a colloid mill. The method can be used. As a mixing procedure, the metal colloid particles, the dispersion medium, and the reducing substance may be mixed at the same time, but the metal colloid particles dispersed in the dispersion medium are first prepared or prepared in advance. It is preferable to add and mix a reducing substance into the metal colloid solution.

  In addition to the metal colloid particles, the dispersion medium, and the reducing substance, additives such as a surfactant, a dispersant, a thickener, a plasticizer, and an antifungal agent are appropriately added to the fluid composition of the present invention. It can also be blended. The surfactant is preferable because it has an effect of further improving the dispersion stability of the metal colloid particles and an effect of controlling the rheological properties of the fluid composition and improving the coating property. For example, a quaternary ammonium salt or the like is used. Use of known anions such as cationic, carboxylate, sulfonate, sulfate ester, phosphate ester, nonionics such as ether type, ether ester type, ester type, nitrogen-containing type, etc. One or more selected from these can be used. The blending amount of the surfactant varies depending on the type of metal colloid particles and the like, and is appropriately set according to the coating composition. Generally, 0.01 to 0.5 parts by weight with respect to 1 part by weight of the metal colloid particles. The range of is preferable. In addition, phenol resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, diallyl phthalate resin, oligoester acrylate resin, xylene resin, bismaleimide triazine resin, furan resin as long as the effects of the present invention are not impaired. Organic curable binders such as urea resin, polyurethane resin, melamine resin, and silicon resin may be included. The blending amount of the curable binder can be appropriately set according to the use scene. When forming an electrode or a wiring pattern, the curable binder is not blended, or 0 to 0.1 to 1 part by weight of the metal colloid particles. It is appropriate to blend in the range of% by weight.

  The electrode and the wiring pattern of the present invention are obtained by applying the fluid composition to a substrate by a method such as screen printing or ink jet printing, followed by heating and baking, and a metal in the fluid composition. Since the colloidal particles are highly dispersed, it has a uniform composition with few defects and excellent electrical characteristics. This electrode can be used as a circuit of a printed wiring board and other fine conductive members.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Preparation of metal colloidal particles 50 g of silver nitrate as the metal compound and 1.6 g of the sulfur compound 3-mercaptopropionic acid as the protective colloid are dissolved in 220 ml of pure water, 70 ml of 28% ammonia water is added, and a solution with a pH of 11.6 is added. It was adjusted. On the other hand, 2.1 g of sodium borohydride as a reducing agent was dissolved in 295 ml of pure water to which 4 ml of 28% ammonia water was added. Both were dripped simultaneously in 600 milliliters of pure water over 30 minutes, silver nitrate was reduced, and silver colloidal particles having 3-mercaptopropionic acid deposited on the surface were produced in the medium. Next, the medium liquid of the obtained silver colloid particles is adjusted to pH 2.5 with nitric acid (30%), the silver colloid particles are settled, and the silver colloid particles are filtered by a vacuum filter. The filtrate was washed with water until the specific conductivity of the filtrate became 10 μS / cm or less, and then re-dispersed in water to obtain an aqueous silver colloid solution (containing 50% by weight of silver colloid particles).

Examples 1-3, Comparative Example 1
Using the silver colloid solution, fluid compositions of the present invention and comparison targets were obtained according to the formulations shown in Table 1. Each is designated as Samples A to D.

*）銀コロイド粒子１重量部に対し、保護コロイドとしてメルカプトプロピオン酸を
０．０３重量部含む。
**）分散剤（有効成分４０重量％：ビックケミー社製）

*) 0.03 part by weight of mercaptopropionic acid is contained as a protective colloid with respect to 1 part by weight of silver colloidal particles.
**) Dispersant (active ingredient 40% by weight: manufactured by Big Chemie)

Evaluation 1
After applying the fluid compositions (Samples A to D) of Examples 1 to 3 and Comparative Example 1 immediately after production and 1 month and 2 months after production on a glass plate with an # 16 bar coater and air-drying And preheating at a temperature of 70 ° C. for 10 minutes and further baking at a temperature of 150 ° C. for 30 minutes. The appearance of the obtained coated product was visually determined, and the volume resistivity was measured using a Loresta-GP type low resistivity meter (manufactured by Mitsubishi Chemical Corporation). The results are shown in Table 2. “◯” in the appearance in Table 2 indicates that there is a good metallic luster, “Δ” indicates that there is a slight metallic luster, and “×” indicates that it is cloudy. Moreover, the surface state of each coating material of sample A and D was image | photographed with the scanning electron microscope. It can be seen that the flowable composition of the present invention is excellent in stability with almost no decrease in the appearance and conductivity of the coated product even after storage.

  Since the fluid composition of the present invention can form a coating film that exhibits excellent conductivity and the like even when stored for a long period of time, it is easy to form uniform electrodes and wiring. It can be used for forming electrodes and wiring patterns.

FIG. 1 is an electron micrograph (magnification: 7300 times) of the surface of a coated material obtained by the method of Evaluation 1 immediately after production of the fluid composition (sample A) obtained in Example 1. FIG. 2 is an electron micrograph (magnification: 7300 times) of the surface of the coated material obtained by the method of Evaluation 1 after the fluid composition (sample A) obtained in Example 1 was stored for 2 months after production. FIG. 3 is an electron micrograph (magnification: 7300 times) of the surface of a coated product obtained by the method of Evaluation 1 immediately after production of the fluid composition (sample D) obtained in Comparative Example 1. FIG. 4 is an electron micrograph (magnification: 7300 times) of the coated surface obtained by the method of Evaluation 1 after the fluid composition (sample D) obtained in Comparative Example 1 was stored for 1 month after production. FIG. 5 is an electron micrograph (magnification: 7300 times) of the surface of the coated material obtained by the method of Evaluation 1 after the fluid composition (Sample D) obtained in Comparative Example 1 was stored for 2 months after production.

Claims (6)

A fluid composition comprising a mixture of at least metal colloidal particles, a dispersion medium, and at least one reducing substance selected from hydrazine or a hydrate thereof, a hydrazine compound, and aldehydes ,
The dispersion medium contains at least one organic solvent selected from N-methylformamide, dimethyl sulfoxide, 4-butyrolactone, acetamide, 1,3-dimethyl-2-imidazolidinone and water,
The water is at least 50% by weight with respect to 100% by weight of the dispersion medium,
At least 5 wt.% Content to the composition 100% by weight of the metal colloid particles,
Ri Na and said reducing substance incorporated 0.1 to 50 parts by weight per 100 parts by weight of the metal colloid particles,
A flowable composition characterized by containing substantially no binder . 2. The fluid composition according to claim 1, wherein the metal colloid particles have a sulfur compound on the surface thereof. The fluid composition according to claim 1 or 2 , wherein the metal colloidal particles are silver or copper colloidal particles. An electrode used as a fine conductive member formed by applying the fluid composition according to any one of claims 1 to 3 . It forms using the fluid composition in any one of Claims 1-3, The wiring pattern characterized by the above-mentioned. A method for producing a fluid composition comprising a step of mixing at least a reducing substance into a mixture containing at least metal colloid particles and a dispersion medium,
The content of the metal colloidal particles is at least 5% by weight with respect to 100% by weight of the flowable composition;
The reducing substance is at least one selected from hydrazine or a hydrate thereof, a hydrazine compound, and aldehydes;
0.1 to 50 parts by weight of the reducing substance is blended with respect to 100 parts by weight of the metal colloid particles,
The dispersion medium in the flowable composition contains at least one organic solvent selected from N-methylformamide, dimethyl sulfoxide, 4-butyrolactone, acetamide, 1,3-dimethyl-2-imidazolidinone and water,
The water is at least 50% by weight with respect to 100% by weight of the dispersion medium in the flowable composition;
A method for producing a flowable composition wherein substantially no binder is mixed in the step.

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