JP6110464B2 - Silver-coated flaky glass powder and method for producing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a silver-coated flaky glass powder and a method for producing the same, and in particular, for conductive pastes used for electronic components such as internal electrodes of multilayer capacitors, conductor patterns of circuit boards, and electrodes and circuits of boards such as solar cells. Relates to a silver-coated flaky glass powder and a method for producing the same.

  Conventionally, silver powder (excellent in electrical conductivity and oxidation resistance) is used in organic components such as resins to form internal electrodes of multilayer capacitors, conductor patterns of circuit boards, and electrodes and circuits of boards such as solar cells. A conductive paste dispersed in is used. Generally, the conductive paste is classified into a fired conductive paste and a resin-cured conductive paste. In the case of the firing type conductive paste, the conductor is formed by firing, but in the case of the resin curing type conductive paste, the silver powders are brought into contact with each other due to volume shrinkage of the resin and are electrically connected. Therefore, flaky silver powder having a large contact area is used in the resin curable conductive paste (see, for example, Patent Document 1).

  In recent years, the price of metals such as silver has risen, and even if the amount of metal used is reduced, a conductive paste having conductivity is desired. As such a conductive paste, a conductive inorganic powder in which the surface of a scaly nonmetallic inorganic powder such as glass flakes is coated with a conductive material such as silver by electroless plating, and a liquid resin composition There has been proposed a conductive composition (see, for example, Patent Document 2).

Japanese Patent No. 3874634 (paragraph number 0006) JP 59-152935 A (page 1-2)

  However, the conductive composition of Patent Document 2 has insufficient conductivity, and is used as a conductive paste for forming internal electrodes of multilayer capacitors, conductor patterns of circuit boards, electrodes and circuits of boards such as solar cells, and the like. Cannot be used.

  Therefore, in view of such conventional problems, the present invention provides a silver-coated flaky glass powder capable of forming a conductive paste having excellent conductivity even if the amount of silver used is reduced, and the production thereof. It aims to provide a method.

  As a result of diligent research to solve the above problems, the present inventors have coated the surface of the flaky glass powder with silver and attached a surface treatment agent to the surface of the flaky glass powder coated with silver. Thus, it was found that a silver-coated flaky glass powder capable of forming a conductive paste having excellent conductivity even if the amount of silver used was reduced, and completed the present invention. .

That is, the method for producing a silver-coated flaky glass powder according to the present invention includes a step of coating the surface of the flaky glass powder with silver, and a step of attaching a surface treatment agent to the surface of the flaky glass powder coated with silver. And. In this method for producing a silver-coated flaky glass powder, the step of coating with silver is performed by immersing the flaky glass powder in a silver ion-containing solution, adding a complexing agent or an alkali and a reducing agent to the solution, and depositing the solution. Preferably, the method comprises a step of coating the surface of the flaky glass powder with the finished silver. Moreover, it is preferable to provide the process of immersing tin ion on the surface of flake-like glass powder by immersing flake-like glass powder in a solution containing tin ions before the step of coating with silver. Moreover, it is preferable that the step of attaching the surface treatment agent includes a step of adding the surface treatment agent to the solution. The surface treatment agent is preferably at least one selected from the group consisting of fatty acids, fatty acid salts, surfactants, organometallic compounds, chelating agents, and polymer dispersants. Further, it is preferable aspect ratio of the flaky glass powder is 3 or more, an average particle size D ₅₀ by laser diffraction method flaky glass powder is preferably a 1 to 8 .mu.m. Further, the silver content in the silver-coated flaky glass powder is preferably 10% by mass or more.

The silver-coated flaky glass powder according to the present invention is characterized in that a surface treatment agent is attached to the surface of the flaky glass powder coated with silver. In this silver-coated flaky glass powder, the surface treatment agent is preferably at least one selected from the group consisting of fatty acids, fatty acid salts, surfactants, organometallic compounds, chelating agents, and polymer dispersants. Further, it is preferable aspect ratio of the flaky glass powder is 3 or more, an average particle size D ₅₀ by laser diffraction method of the silver-coated flaky glass powder is preferably a 1 to 8 .mu.m. Further, the silver content in the silver-coated flaky glass powder is preferably 10% by mass or more, and the ignition loss value of the silver-coated flaky glass powder is preferably 0.01 to 1%.

  Furthermore, the conductive paste and the resin curable conductive paste according to the present invention are characterized by using the above silver-coated flaky glass powder as a conductor.

  According to the present invention, it is possible to produce a silver-coated flaky glass powder capable of forming a conductive paste having excellent conductivity even if the amount of silver used is reduced.

  The embodiment of the method for producing a silver-coated flaky glass powder according to the present invention comprises a step of coating the surface of the flaky glass powder with silver, and a surface treatment agent is attached to the surface of the flaky glass powder coated with silver. A step of causing

  The step of coating with silver was performed by a wet reduction method in which flaky glass powder was immersed in a silver ion-containing solution, a complexing agent or an alkali and a reducing agent were added to the solution, and silver particles were reduced and precipitated. It preferably comprises a step of coating the surface of the flaky glass powder with silver. In this step, silver particles are added to the surface of the flaky glass powder by adding a complexing agent or an alkali and a reducing agent to the slurry obtained by immersing the flaky glass powder while stirring in the silver ion-containing solution. To precipitate. In this step, the entire surface of the flaky glass powder may not be completely covered with silver, and a part of the surface of the flaky glass powder may be exposed. Thus, even if a part of the surface of the flaky glass powder is exposed, when the silver-coated flaky glass powder is used for a resin-cured conductive paste, the surface of the flaky glass powder and the surface treatment It is considered that the fine inhomogeneity of silver covering the surface of the flaky glass powder is not so affected by the interaction with the agent. In addition, before the step of coating with silver, the step of immersing the flaky glass powder in the tin ion-containing solution to deposit tin ions on the surface of the flaky glass powder (sensitizing step) May be provided.

  As the silver ion-containing solution, an aqueous silver nitrate solution or the like can be used. By adding a complexing agent or an alkali to the silver ion-containing solution, an aqueous solution or slurry containing a silver salt complex or a silver intermediate can be produced. As a complexing agent for producing an aqueous solution or slurry containing a silver salt complex, aqueous ammonia, ammonium salt, chelate compound and the like can be used. As an alkali for producing an aqueous solution or slurry containing a silver intermediate, sodium hydroxide, sodium chloride, sodium carbonate or the like can be used. Among these, it is preferable to add aqueous ammonia to an aqueous silver nitrate solution to produce an aqueous silver ammine complex solution. Since the coordination number of ammonia in the ammine complex is 2, the addition amount of ammonia is 2 moles or more per mole of silver. However, if the addition amount of ammonia is too large, the complex is too stabilized and the reduction is difficult to proceed. Therefore, the amount is preferably 8 mol or less per 1 mol of silver. In addition, if adjustment, such as increasing the addition amount of a reducing agent, is performed, even if the addition amount of ammonia exceeds 8 mol, a silver coating flake-like glass powder can be obtained.

  As a reducing agent, ascorbic acid, sulfite, alkanolamine, hydrogen peroxide solution, formic acid, ammonium formate, sodium formate, glyoxal, tartaric acid, sodium hypophosphite, sodium borohydride, hydroquinone, hydrazine, hydrazine compound, pyrogallol, One or more of glucose, gallic acid, formalin, anhydrous sodium sulfite, Rongalite and the like can be used. Among these, it is preferable to use one or more selected from the group consisting of ascorbic acid, alkanolamine, sodium borohydride, hydroquinone, hydrazine and formalin, more preferably formalin or hydrazine, Most preferably it is used. The addition amount of the reducing agent is preferably 1 equivalent or more with respect to silver in order to increase the yield of silver. When a reducing agent having a weak reducing power is used, 2 equivalents or more with respect to silver For example, 10-20 equivalent may be sufficient.

  In the step of attaching the surface treatment agent, the surface treatment agent is added to the silver ion-containing solution in which the flaky glass powder is immersed, and the surface treatment agent is attached to the surface of the flaky glass powder (coated with silver). Is preferred. When the silver-coated flaky glass powder to which the surface treatment agent is attached is used as a resin-cured conductive paste, the dispersibility of the silver-coated flaky glass powder in the paste is improved, and the orientation is improved. Since the contact area between the coated flaky glass powders increases, the resistance of the conductive film obtained by applying and drying this paste can be reduced. In this step, it is preferable to appropriately perform stirring and temperature adjustment of the solution.

  The surface treatment agent may be added before, during or after the addition of the reducing agent. The addition amount of the surface treatment agent is preferably 0.01 to 1% by mass with respect to the silver in the solution, and within this range, the silver-coated glass is adjusted so as to have desired characteristics and ignition loss value It is preferable to do this.

  The surface treatment agent adhering to the surface of the silver-coated flaky glass powder is a method for qualitative analysis of the type of the silver-coated flaky glass powder treatment agent by Fourier transform infrared analysis (FT-IR), silver coating A method in which the silver component of the flaky glass powder is dissolved in nitric acid and extracted with a solvent such as chloroform and then measured by an automatic carbon analyzer or gas chromatograph mass spectrometer (GC-MS). The silver-coated flaky glass powder is mixed with hydrochloric acid. Then, it can be analyzed by a method of calculating from the absorbance of the liquid obtained by heating.

  As the surface treatment agent, one or more selected from the group consisting of fatty acids, fatty acid salts, surfactants, organometallic compounds, chelating agents and polymer dispersants can be used.

  Examples of fatty acids include propionic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, acrylic acid, oleic acid, linoleic acid, arachidonic acid and the like.

  Examples of fatty acid salts are salts of fatty acids with metals such as lithium, sodium, potassium, barium, magnesium, calcium, aluminum, iron, cobalt, manganese, lead, zinc, tin, strontium, zirconium, silver, copper, etc. Can be mentioned.

  Examples of surfactants include anionic surfactants such as alkylbenzene sulfonates and polyoxyethylene alkyl ether phosphates, cationic surfactants such as aliphatic quaternary ammonium salts, and amphoteric interfaces such as imidazolinium betaine. Nonionic surfactants, such as an activator, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, etc. can be mentioned.

  Examples of organometallic compounds include acetylacetone tributoxyzirconium, magnesium citrate, diethylzinc, dibutyltin oxide, dimethylzinc, tetra-n-butoxyzirconium, triethylindium, triethylgallium, trimethylindium, trimethylgallium, monobutyltin oxide, tetraisocyanate Examples thereof include silane, tetramethylsilane, tetramethoxysilane, polymethoxysiloxane, monomethyltriisocyanate silane, silane coupling agent, titanate coupling agent, and aluminum coupling agent.

  Examples of chelating agents include imidazole, oxazole, thiazole, selenazole, pyrazole, isoxazole, isothiazole, 1H-1,2,3-triazole, 2H-1,2,3-triazole, 1H-1,2,4- Triazole, 4H-1,2,4-triazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole Azole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1H-1,2,3,4-tetrazole, 1,2, 3,4-oxatriazole, 1,2,3,4-thiatriazole, 2H-1,2,3,4-tetrazole, 1,2,3,5-oxatriazole, 1,2 3,5-thiatriazole, indazole, benzimidazole, benzotriazole, oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid List acid, phthalic acid, isophthalic acid, terephthalic acid, glycolic acid, lactic acid, oxybutyric acid, glyceric acid, tartaric acid, malic acid, tartronic acid, hydroacrylic acid, mandelic acid, citric acid, ascorbic acid or their salts Can do.

  Examples of the polymer dispersant include peptides, gelatin, collagen peptides, albumin, gum arabic, protalbic acid, lysalbic acid and the like.

  Among these surface treatment agents, it is preferable to use at least one selected from the group consisting of azoles, fatty acids and salts thereof, and one type selected from the group consisting of oleic acid, stearic acid and salts thereof It is more preferable to use the above.

Flaky glass powder used in the manufacturing method of the silver-coated flaky glass powder, so that the average particle diameter D ₅₀ of the silver-coated flaky glass powder to the desired size, the average particle size D ₅₀ by laser diffraction method Is preferably 1 to 8 μm. The aspect ratio (average particle diameter D ₅₀ / average thickness) of the flaky glass powder is preferably 3 or more. When the aspect ratio is less than 3, the shape of the particles of the flaky glass powder becomes nearly spherical, so that sufficient conductivity can be obtained when the silver-coated flaky glass powder is used in a resin-cured conductive paste. There are cases where it is not possible.

The flake glass powder is preferably lead-free glass in consideration of the influence on the environment, and may be glassy and mixed with metal. For _example, flake-like glass _powder, flake glass powder consisting of _{SiO 2 · Al 2 O 3 ·} CaO · MgO · B 2 O 3, SiO 2 · CaO · MgO · R 2 made of _{SiO 2 · Al 2 O 3 ·} MgO flaky glass powder consisting of _{O · Al 2 O 3 · B} 2 O 3 (R 2 O is an alkali metal oxide) or the like can be used.

  The silver-coated glass-containing slurry obtained after the step of attaching the surface treatment agent is filtered and washed with water, whereby a cake having almost no fluidity is obtained. In order to accelerate the drying of the cake or prevent aggregation at the time of drying, the water in the cake may be replaced with a lower alcohol or a polyol. The cake is dried by a dryer such as a forced circulation air dryer, vacuum dryer, airflow dryer, etc., and then crushed to obtain silver-coated flaky glass powder. Moreover, you may perform a classification process after crushing. In addition, you may dry, grind | pulverize, and classify | categorize using the integrated apparatus (For example, the dry meister made from Hosokawa Micron Corporation, a micron dryer etc.) which can perform drying, grinding | pulverization, and classification.

  In this way, a silver-coated flaky glass powder having a surface treatment agent attached to the surface of the flaky glass powder coated with silver can be obtained.

The silver-coated flaky glass powder is preferably an average particle diameter D ₅₀ is 1~8μm by laser diffraction method, more preferably from 3 to 7 [mu] m. If the average particle size is small, when the conductive film is formed using a resin curable conductive paste, the film density in the conductive film is increased, and therefore the conductivity can be increased.

The aspect ratio (average particle diameter D ₅₀ / average thickness) of the silver-coated flaky glass powder is preferably 3 or more. When the aspect ratio is less than 3, the shape of the silver-coated flaky glass powder particles is close to a sphere, so that sufficient conductivity may not be obtained when used in a resin-cured conductive paste.

The tap density of the silver-coated flaky glass powder is preferably 1 g / cm ³ or more. If the tap density is too low, when used in a resin-cured conductive paste, the filling property is deteriorated, the contact area between the silver-coated flaky glass powders is reduced, and sufficient conductivity cannot be obtained. There is a case.

  In addition, the silver content in the silver-coated flaky glass powder is 10% by mass or more based on the total silver-coated flaky glass powder because sufficient conductivity may not be obtained if it is less than 10% by mass. It is preferably 30% by mass or more, and most preferably 50% by mass or more. This silver content can be calculated from the amount of silver subjected to the reaction and the amount of flaky glass powder when there is no residual silver ion in the reaction solution, but the silver component of the silver-coated flaky glass powder is It can also be directly measured by chemical analysis such as inductively coupled plasma (ICP) after dissolution with nitric acid and removal of glass components by filtration.

  Furthermore, the ignition loss value of the silver-coated flaky glass powder is preferably 0.01 to 1%. If the ignition loss value is too low, the dispersibility of the silver-coated flaky glass powder in the paste deteriorates and the orientation deteriorates when used in a resin-curing conductive paste, resulting in a silver-coated flaky glass powder. Since the contact area between each other decreases, good conductivity cannot be obtained in the paste. On the other hand, if the ignition loss value is too high, the organic component in the paste inhibits conduction, so that sufficient conductivity is obtained. May not be able to get.

  A conductive paste can be obtained by mixing the obtained silver-coated flaky glass powder with a resin (adding a curing agent and a viscosity modifier as necessary) and performing a kneading treatment. As the resin to be mixed, one or more of epoxy resin, acrylic resin, polyester resin, polyimide resin, polyurethane resin, phenoxy resin, silicone resin, ethyl cellulose, and the like can be used.

  The viscosity of the conductive paste is preferably 10 to 1,000 Pa · s at 25 ° C. If it is less than 10 Pa · s, bleeding may occur during printing of the paste, and if it exceeds 1,000 Pa · s, uneven printing may occur.

  Hereinafter, examples of the silver-coated flaky glass powder and the production method thereof according to the present invention will be described in detail.

[Example 1]
17 g of flaky glass powder (fine flake MTD010FYX manufactured by Nippon Sheet Glass Co., Ltd.) having an average particle diameter of 9.5 μm, average thickness of 0.7 μm and aspect ratio of 13.6 μm made of SiO ₂ / Al ₂ O ₃ / MgO The flaked glass powder was crushed by putting it into a vibrating ball mill (TI-100 manufactured by HEIKO) together with 553 g (diameter 1.6 mm) and crushing for 10 minutes at an amplitude of 6.4 mm and a frequency of 1493 vpm. After adding 0.3 g of the obtained flaky glass powder to 30 mL of isopropyl alcohol and dispersing for 5 minutes with an ultrasonic cleaner with an output of 50 W, a microtrack particle size distribution measuring apparatus (Honeywell 9320X-100 manufactured by Nikkiso Co., Ltd.) Was used to measure the average particle diameter D ₅₀ by laser diffraction method, and was 4.7 μm. In addition, since it is thought that the longitudinal direction of the flaky glass powder is preferentially crushed, assuming that the average thickness does not change, the aspect ratio of the obtained flaky glass powder was 6.7. .

After 8.6 g of the flaky glass powder thus crushed was immersed in an acidic aqueous solution of stannous chloride, it was filtered and washed with water to obtain a flaky glass powder coated with Sn ²⁺ .

In this way, the Sn ²⁺ is put into pure water being stirred in a reaction vessel in the flaky glass powder was deposited, dispersed flake glass powder Sn ²⁺ was deposited in pure water therein Was charged with 28.4 g of an aqueous silver nitrate solution containing 8.6 g of silver, and silver was deposited on the surface of the flaky glass powder.

  Next, 19.5 g of 28% by mass aqueous ammonia and 4.0 g of 20% by mass aqueous sodium hydroxide were added to the reaction vessel to obtain an aqueous silver ammine complex salt solution. The liquid temperature of this silver ammine complex salt aqueous solution was adjusted to 30 ° C., and 24.2 g of an 8% by mass hydrazine monohydrate aqueous solution was added to further precipitate silver on the surface of the flaky glass powder.

  After silver was sufficiently precipitated, 0.6 g of an ethanol solution of 20% by mass of oleic acid was added as a surface treatment agent to obtain a slurry containing silver-coated flaky glass powder. This silver-coated flaky glass powder-containing slurry was filtered and washed with water to obtain a cake.

  Next, the obtained cake was dried with a vacuum dryer at 75 ° C. for 10 hours and crushed with a coffee mill to obtain a silver-coated flaky glass powder containing 50% by mass of silver.

This way, silver coated flake glass powder obtained by, with measuring the average particle diameter D ₅₀ and the BET specific surface area by the laser diffraction method was calculated tap density and ignition loss value.

The average particle diameter D ₅₀ of the silver-coated flaky glass powder by the laser diffraction method was determined by adding 0.3 g of silver-coated flaky glass powder to 30 mL of isopropyl alcohol and dispersing it for 5 minutes with an ultrasonic cleaner with an output of 50 W. It measured using the micro track particle size distribution measuring apparatus (Honeywell 9320X-100 by Nikkiso Co., Ltd.). As a result, the average particle size _{D 50} by laser diffraction method was 5.7 .mu.m.

The BET specific surface area of the silver-coated flaky glass powder was determined by degassing the silver-coated flaky glass powder at 60 ° C. for 10 minutes, and then using a specific surface area measuring device (Monosorb manufactured by Quanta Chrome) using nitrogen. It was measured by the BET one point method by adsorption. As a result, the BET specific surface area was 1.09 m ² / g.

The tap density of the silver-coated flaky glass powder is as follows: 15 g of silver-coated flaky glass powder is weighed and placed in a 20 mL test tube, tapped 1,000 times with a drop of 20 mm, and tap density = sample mass (15 g) / after tapping Was calculated from the sample volume (cm ³ ). As a result, the tap density was 1.85 g / cm ³ .

  The ignition loss value of the silver-coated flaky glass powder was as follows: 3 g of silver-coated flaky glass powder was weighed (w1), put in a magnetic crucible, and slightly heated at 800 ° C. for 30 minutes with an electric furnace (KM-1302 manufactured by Advantech). After heating, the mixture was cooled and weighed (w2) again to determine the ignition loss value (%) = (w1−w2) × 100 / w1. As a result, the ignition loss value was 0.06%.

  These results are shown in Tables 1 and 2.

  Further, 90.0 parts by mass of the obtained silver-coated flaky glass powder, 8.3 parts by mass of an epoxy resin (EP-4901E manufactured by Adeka), and a curing agent (Amicure MY-24 manufactured by Ajinomoto Fine Techno Co., Ltd.) After mixing with 1.7 parts by mass and adding diethylene glycol monoethyl ether acetate as a viscosity modifier (so that the paste viscosity after kneading treatment is 10 to 1000 Pa · s), propellerless self-revolving stirring and defoaming By mixing for 30 seconds using an apparatus (AR250 manufactured by Shinky Co., Ltd.) and using a three roll (EXAKT 80S) and passing between the rolls from a roll gap of 100 μm to 20 μm, a conductive process is performed. Sex paste was obtained.

  The conductive paste thus obtained was printed in an 8 mm × 10 mm rectangle on an alumina substrate with a squeegee pressure of 0.3 MPa using a screen printing apparatus (MT-320T manufactured by Microtech), and then air circulation drying A conductive film was produced by heating at 200 ° C. for 40 minutes using a machine, and the film thickness and volume resistivity of the obtained conductive film were measured.

The film thickness of the conductive film is measured using a surface roughness meter (SE-30D manufactured by Kosaka Laboratory Ltd.) by measuring the level difference between the part on the alumina substrate where the conductive film is not printed and the part of the conductive film. Sought by. In addition, the volume resistivity of the conductive film was measured by measuring the surface resistivity of the conductive film using a resistivity meter (MCP-T410 manufactured by Mitsubishi Chemical Corporation), and the volume (determined from the film thickness and area) of the conductive film. And surface resistivity. As a result, the film thickness of the conductive film was 28.5 μm, and the volume resistivity was 5.5 × 10 ⁻⁴ Ω · cm.

  These results are shown in Table 3.

[Example 2]
About the flaky glass powder and the silver-coated flaky glass powder obtained by the same method as in Example 1 except that the amount of flaky glass powder input to the vibrating ball mill was 10 g and the crushing time was 2 minutes, in the same manner as in example 1, by measuring the average particle size D ₅₀ by laser diffraction method flaky glass powder is calculated aspect ratio, average particle diameter D ₅₀ of the silver-coated flaky glass powder by a laser diffraction method and While measuring the BET specific surface area, the tap density and the ignition loss value were calculated.

As a result, the average particle size D ₅₀ by laser diffraction method flaky glass powder is 6.8 [mu] m, the aspect ratio was 9.7. Further, the average particle diameter D ₅₀ of the silver-coated flaky glass powder by laser diffraction method is 7.4 μm, the BET specific surface area is 1.25 m ² / g, the tap density is 1.68 g / cm ³ , and the ignition loss value is 0. 0.09%. These results are shown in Tables 1 and 2.

Moreover, about the electrically conductive film obtained by the method similar to Example 1 using the obtained silver covering flaky glass powder, the film thickness and the volume resistivity were calculated | required by the method similar to Example 1. The film thickness of the conductive film was 37.8 μm, and the volume resistivity was 9.9 × 10 ⁻⁴ Ω · cm. These results are shown in Table 3.

[Example 3]
About the flaky glass powder and silver-coated flaky glass powder obtained by the same method as in Example 1 except that the amount of flaky glass powder input to the vibrating ball mill was 12 g and the crushing time was 70 minutes, in the same manner as in example 1, by measuring the average particle size D ₅₀ by laser diffraction method flaky glass powder is calculated aspect ratio, average particle diameter D ₅₀ of the silver-coated flaky glass powder by a laser diffraction method and While measuring the BET specific surface area, the tap density was calculated.

As a result, the average particle size D ₅₀ by laser diffraction method flaky glass powder is 2.7 .mu.m, the aspect ratio was 3.9. Further, the average particle diameter D ₅₀ of the silver-coated flaky glass powder by laser diffraction method was 3.8 μm, the BET specific surface area was 1.34 m ² / g, and the tap density was 1.83 g / cm ³ . These results are shown in Tables 1 and 2.

Moreover, about the electrically conductive film obtained by the method similar to Example 1 using the obtained silver covering flaky glass powder, the film thickness and the volume resistivity were calculated | required by the method similar to Example 1. The film thickness of the conductive film was 25.8 μm, and the volume resistivity was 1.2 × 10 ⁻³ Ω · cm. These results are shown in Table 3.

[Example 4]
The flake glass powder is obtained by the same method as in Example 1 except that the amount of flake glass powder charged into the vibrating ball mill is 10 g and the crushing time is 7 minutes, and 15.5 mass as the surface treatment agent. A silver-coated flaky glass powder was obtained in the same manner as in Example 1 except that 0.74 g of an aqueous emulsion of 4% stearic acid was used. The thus-obtained flake-like glass powder and silver-coated flaky glass powder, in the same manner as in Example 1, the aspect ratio by measuring the average particle size D ₅₀ by laser diffraction method flaky glass powder calculated, with measuring the average particle diameter D ₅₀ and the BET specific surface area by the laser diffraction method of the silver-coated flaky glass powder was calculated tap density.

As a result, the average particle size D ₅₀ by laser diffraction method flaky glass powder is 4.4 [mu] m, the aspect ratio was 6.3. The average particle diameter _{D 50} of the silver-coated flaky glass powder by a laser diffraction method is 5.0 .mu.m, BET specific surface area of 1.65 m ² / g, the tap density was 1.67 g / cm ^3. These results are shown in Tables 1 and 2.

Moreover, about the electrically conductive film obtained by the method similar to Example 1 using the obtained silver covering flaky glass powder, the film thickness and the volume resistivity were calculated | required by the method similar to Example 1. The film thickness of the conductive film was 27.8 μm, and the volume resistivity was 7.3 × 10 ⁻⁴ Ω · cm. These results are shown in Table 3.

[Comparative Example 1]
The silver-coated flaky glass powder obtained by the same method as in Example 1 except that the crushing treatment was not performed, the average particle size of the silver-coated flaky glass powder by the laser diffraction method was the same as in Example 1. The diameter D ₅₀ and the BET specific surface area were measured, and the tap density was calculated.

As a result, the average particle diameter _{D 50} of the silver-coated flaky glass powder by a laser diffraction method 9.7Myuemu, BET specific surface area of 0.99 m ² / g, the tap density was 1.91 g / cm ^3. These results are shown in Tables 1 and 2.

Moreover, about the electrically conductive film obtained by the method similar to Example 1 using the obtained silver covering flaky glass powder, the film thickness and the volume resistivity were calculated | required by the method similar to Example 1. The film thickness of the conductive film was 24.3 μm, and the volume resistivity was 5.2 × 10 ⁻³ Ω · cm. These results are shown in Table 3.

[Comparative Example 2]
Instead of flaky glass powder, glass powder having an average particle diameter of 4.5 μm made of SiO ₂ , B ₂ O ₃ , CaO, and Al ₂ O ₃ (EMB-10 manufactured by Potters Ballotini) The silver-coated spherical glass powder obtained by the same method as in Example 1 except that the crushing treatment was not performed, and the silver-coated spherical glass powder was laser-diffracted by the same method as in Example 1. with measuring the average particle diameter D ₅₀ and the BET specific surface area was calculated tap density.

As a result, the average particle diameter _{D 50} of the silver-coated spherical glass powder by a laser diffraction method is 4.5 [mu] m, BET specific surface area of 1.62M ² / g, the tap density was 2.05 g / cm ^3. These results are shown in Tables 1 and 2.

Further, using the obtained silver-coated spherical glass powder, the film thickness and the volume resistivity were obtained by the same method as in Example 1 for the conductive film obtained by the same method as in Example 1. The film thickness of the conductive film was 40.0 μm, and the volume resistivity was 1.9 × 10 ⁻³ Ω · cm. These results are shown in Table 3.

[Comparative Example 3]
The flake glass powder was obtained by the same method as in Example 1 except that the amount of flake glass powder charged into the vibrating ball mill was 11 g and the crushing time was 10 minutes, and no surface treatment agent was used. Except for the above, a silver-coated flaky glass powder was obtained in the same manner as in Example 1. The thus-obtained flake-like glass powder and silver-coated flaky glass powder, in the same manner as in Example 1, the aspect ratio by measuring the average particle size D ₅₀ by laser diffraction method flaky glass powder calculated, with measuring the average particle diameter D ₅₀ and the BET specific surface area by the laser diffraction method of the silver-coated flaky glass powder was calculated tap density.

As a result, the average particle size D ₅₀ by laser diffraction method flaky glass powder is 4.0 .mu.m, the aspect ratio was 5.7. The average particle diameter _{D 50} of the silver-coated flaky glass powder by a laser diffraction method is 5.3 .mu.m, BET specific surface area of 1.96M ² / g, the tap density was 0.85 g / cm ^3. These results are shown in Tables 1 and 2.

Moreover, about the electrically conductive film obtained by the method similar to Example 1 using the obtained silver covering flaky glass powder, the film thickness and the volume resistivity were calculated | required by the method similar to Example 1. The film thickness of the conductive film was 44.0 μm, and the volume resistivity was 4.4 × 10 ⁻³ Ω · cm. These results are shown in Table 3.

[Comparative Example 4]
The flake glass powder was obtained by the same method as in Example 1 except that the amount of flake glass powder charged into the vibrating ball mill was 10 g and the crushing time was 6 minutes. The obtained flake glass powder was 16 g. A silver-coated flaky glass powder containing 5% by mass of silver was obtained in the same manner as in Example 1 except that the weight of the raw material for silver deposition and coating was 1/10 times. . The thus-obtained flake-like glass powder and silver-coated flaky glass powder, in the same manner as in Example 1, the aspect ratio by measuring the average particle size D ₅₀ by laser diffraction method flaky glass powder calculated, with measuring the average particle diameter D ₅₀ and the BET specific surface area by the laser diffraction method of the silver-coated flaky glass powder was calculated tap density.

As a result, the average particle size D ₅₀ by laser diffraction method flaky glass powder is 5.0 .mu.m, the aspect ratio was 6.9. The average particle diameter _{D 50} of the silver-coated flaky glass powder by a laser diffraction method is 5.0 .mu.m, BET specific surface area of 4.08m ² / g, the tap density was 0.61 g / cm ^3. These results are shown in Tables 1 and 2.

  Moreover, about the electrically conductive film obtained by the method similar to Example 1 using the obtained silver covering flaky glass powder, the film thickness and the volume resistivity were calculated | required by the method similar to Example 1. The film thickness of the conductive film was 25.8 μm, and the volume resistivity was over the measurement range and could not be measured. These results are shown in Table 3.

As can be seen from Tables 1 to 3, the silver-coated flaky glass powder of Examples 1 to 4 having a surface treatment agent attached to the surface of the flaky glass powder coated with silver was used for a resin-cured conductive paste. The conductive film thus prepared had a low volume resistivity of 1.2 × 10 ⁻³ Ω · cm or less, and had excellent conductivity. On the other hand, the conductive film produced using the silver-coated flaky glass powder of Comparative Example 3 to which no surface treatment agent is attached as a resin-cured conductive paste has a volume resistivity of 4.4 × 10 ⁻³ Ω. -It was as high as cm and the conductivity was poor. The average particle diameter D ₅₀ of the conductive film of silver-coated flaky glass powder of Comparative Example 1 was prepared using the resin curing type conductive paste is 8μm more than a volume resistivity of 5.2 × 10 ^{- It} was as high as ³ Ω · cm and the conductivity was poor. In addition, the conductive film prepared by using the silver-coated spherical glass powder of Comparative Example 2 in which the particle shape is spherical instead of flaky as a resin-cured conductive paste also has a volume resistivity of 1.9 × 10 ^{−. It} was as high as ³ Ω · cm and the conductivity was poor. Furthermore, the conductive film produced by using the silver-coated flaky glass powder of Comparative Example 4 having a silver content of less than 10% by mass as a resin-cured conductive paste could not conduct.

  Since the silver-coated flaky glass powder according to the present invention can form a conductive paste having excellent conductivity even if the amount of silver used is reduced, the internal electrode of the multilayer capacitor, the conductor pattern of the circuit board, It can be used for the production of an inexpensive conductive paste for use in electronic parts such as electrodes and circuits of substrates such as solar cells.

Claims (10)

The surface of the flaky glass powder having an aspect ratio of 3 to 9.7 and an average particle diameter D ₅₀ by laser diffraction of 1 to 8 μm is coated with silver, and the surface of the flaky glass powder coated with silver A silver-coated flaky glass powder characterized in that a surface treatment agent is adhered to the surface. The silver according to claim 1 , wherein the surface treatment agent is at least one selected from the group consisting of fatty acids, fatty acid salts, surfactants, organometallic compounds, chelating agents, and polymer dispersing agents. Coated flaky glass powder. Wherein the average particle size D ₅₀ by pre sharp Za diffraction method is 3 ~ 7 μm, silver coated flake glass powder according to claim 1 or 2. The silver-coated flaky glass powder according to any one of claims 1 to 3 , wherein the silver content in the silver-coated flaky glass powder is 10% by mass or more. The silver-coated flaky glass powder according to any one of claims 1 to 4 , wherein a loss on ignition value of the silver-coated flaky glass powder is 0.01 to 1%. The silver-coated flaky glass powder has a BET specific surface area of 1.09 to 1.65 m. ² The silver-coated flaky glass powder according to any one of claims 1 to 5, which is / g. The tap density of the silver-coated flaky glass powder is 1-1.85 g / cm. ³ The silver-coated flaky glass powder according to any one of claims 1 to 6, wherein A conductive paste obtained by mixing 90.0 parts by mass of the silver-coated flaky glass powder, 8.3 parts by mass of an epoxy resin and 1.7 parts by mass of a curing agent, adding a viscosity modifier, and kneading. The volume resistivity of the conductive film produced by printing on the substrate and heating is 1.2 × 10 ^-3 The silver-coated flaky glass powder according to any one of claims 1 to 7, wherein it is Ω · cm or less. Characterized by using as the conductor the silver-coated flaky glass powder according to any one of claims 1 to 8, a conductive paste. A resin-cured conductive paste, wherein the silver-coated flaky glass powder according to any one of claims 1 to 8 is used as a conductor.