JPH0234673A - Conductive paint composition - Google Patents

Abstract

PURPOSE:To prepare a conductive paint compsn. with improved salt water resistance without decreasing conductivity by mixing a reducing agent comprising a copper powder, an organozirconate compt. and a carbon powder with a resin binder and a solvent. CONSTITUTION:The title conductive paint compsn. is prepd. by mixing a reducing agent comprising a copper powder, an organozirconate compd. (e.g., isopropyltriisostearoyl zirconate) and a carbon with a resin binder and a solvent (e.g., toluene). The drawbacks of a conventional conductive paint are overcome by the resulting conductive paint compsn. which, without decreasing conductivity, improves resistance to environmental degradation, esp. resistance to salt water so that the compsn. prevents the generation of verdigris even under the condition of salt water spray, thus maintaining the conductivity for a long period. The organozirconate compd. improves the dispersion of the copper powder and the carbon powder in the resin binder and improves long-term resistance to heat and humidity.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to electromagnetic shielding materials, and more specifically,
The present invention relates to an electromagnetic wave shielding square steel conductive coating composition containing carbon powder and an organic zirconate compound as a reducing agent.

[Conventional technology]

As one of the electromagnetic wave shielding materials that protect electronic devices from electromagnetic interference, there are conductive paints that are made by kneading conductive fillers such as nickel powder, silver powder, copper powder, and carbon powder into various resin binders. Apply this to the surface of plastic molded products with a spray brush to shield electromagnetic waves. Among various conductive paints, copper-based conductive paints are
It is cheaper than paints using silver powder or nickel powder, and has excellent shielding properties.

However, copper-based conductive paints have a problem in that they are easily oxidized in environments such as heat and humidity.

Various proposals have been made to solve this problem. For example, surface treatment of copper powder with a coupling agent (Japanese Unexamined Patent Application Publication No. 60-30200), electrolytic copper powder using organic titanium! Covering with
1 and JP-A No. 56-36553), coating copper powder with organic aluminum (JP-A-59-17)
9671), coating with an unsaturated fatty acid and an organic titanium compound (JP 58-74759),
Adding alkanolamine (JP-A-59-36
No. 170), and incorporating anthrazine (Japanese Unexamined Patent Publication No. 163166/1983) have been proposed.

[Problem to be solved by the invention]

By subjecting copper powder to the above-described treatments, certain effects can be obtained.

However, it was not possible to obtain a coating film that had sufficient environmental resistance to be practical, and in particular, the generation of patina and the deterioration of conductivity due to salt spray were significant.

The present invention has been made based on the above background, and its purpose is to solve the above-mentioned drawbacks of the conventional conductive paints and to improve the durability of the paint composition without deteriorating the conductive performance. An object of the present invention is to provide a conductive coating composition with improved environmental properties, particularly salt water resistance.

[Means to solve the problem]

As a result of conducting various tests and research on copper powder and copper-based conductive paint, the present inventor found that an excellent effect can be obtained by including an organic zirconate compound and using carbon powder as a reducing agent. The invention was completed.

That is, the conductive coating composition of the present invention is characterized by containing copper powder, an organic zirconate compound, a reducing agent made of carbon powder, a resin binder, and a solvent.

In a preferred embodiment of this invention, as carbon powder, 5μ
Using fine carbon powder having a number average particle size of m or less, the content of fine carbon powder is 0.1 to 50% by weight based on the weight of copper powder.
It can be done.

This invention will be explained in detail below.

Copper powder The shape of the copper powder used in this invention can be obtained by electrolytic method, reduction method,
There are dendritic, granular, and spherical shapes obtained by the atomization method, and there are also flakes obtained by mechanically processing these.

Examples of copper powder used in this invention have an apparent density of 0, 5 to
3.5g/cm, tap density 1.0-5.0g/cnl
, 1. with the BET method. It has a specific surface area of less than 5 rtf/g, an average particle size of 3 to 20 μm as measured by a light transmission method, and a particle size distribution of 50 μm or less as measured by a light transmission method.

The shielding effect can be improved by processing granular or spherical copper powder into flake powder using a ball mill or the like. Also, V
A good shielding effect can be obtained by mixing dendritic copper powder and granular or spherical copper powder using a mold mixer or the like.

As the raw material copper powder that can be used in this invention, metals such as silver, nickel, zinc, platinum, palladium,
It may be coated in advance with an alloy such as solder, an organic metal compound such as an organosilicon compound, an organotitanium compound or an organoaluminium compound, a surfactant, an amino acid, a carboxylic acid, a derivative thereof, or the like. A preferable raw material coated copper powder is a copper powder in which all or part of the surface of the copper powder is coated with silver.

In addition to the above-mentioned materials, copper powder may be coated with components used in the production of conductive paint in advance.

In addition, as a pretreatment, the oxide film on the surface of the copper powder can be removed using reagents such as inorganic acids, organic acids, various reducing agents, or ammonia gas.
It can be removed by reducing gas such as hydrogen gas.

In this invention, the copper powder may be coated in advance with an organic zirconate compound as an essential component. The coating method includes a method of adding an organic zirconate compound dissolved in a solvent to copper powder (copper powder dispersion bath) and then removing the solvent, and a method of adding the necessary amount of organic zirconate compound to copper powder (copper powder dispersion bath). There is a method of adding and mixing and stirring. When using a dispersion bath of copper powder, the method includes removing the dispersion medium as necessary to obtain copper powder for conductive paint.

The copper powder dispersion bath used in this coating method is one in which the copper powder to be coated is well dispersed in a dispersion medium, and examples of the dispersion medium used here include organic solvents such as water and alcohol. There is. As a preferred dispersion medium,
water, methyl alcohol, ethyl alcohol, toluene,
Examples include hexane. The amount of the dispersion medium is the amount necessary to form a good dispersion state of the copper powder, and is preferably set to the minimum amount possible.

carbon powder In this invention, carbon powder is included in the coating composition.

This carbon powder contributes to the environmental resistance of paints and coatings.

Carbon powder that can be used in this invention includes natural gas,
Carbon blacks obtained by incomplete combustion or pyrolysis of petroleum etc., e.g. channel black, thermal black, furnace black, etc., from metamorphic rocks, e.g. crystalline limestone, crystalline schist, gneiss and metamorphosed coal seams. Examples include graphite, which is obtained by heating anthracite and pitch to high temperatures in an arc furnace.

There are no particular limitations on the manufacturing method or shape of the carbon powder, but
Fine carbon powder is preferred. The size of the carbon powder is, for example, an arithmetic average particle size of 5 μm or less, preferably 1 μm.
The specific surface area is 300 rrr/g by nitrogen adsorption method.
Above, preferably 1000 rtf/g or less.

The content of carbon powder in the conductive coating composition is 0.05 to 75% by weight, preferably 0.1 to 50% by weight, based on the weight of copper powder. If it is less than 0.1% by weight, the environmental resistance, especially the salt water resistance, of the coating film will begin to gradually decrease, and patina and conductivity will decrease, and if it is less than 0.05% by weight, this tendency will be significant. When it exceeds 50% by weight, the conductivity of the coating film begins to decrease and its performance as a conductive paint decreases;
This is because the tendency becomes more pronounced when the value is exceeded.

The carbon powder used in this invention may be coated with an organic zirconate compound in advance like the copper powder.

Organic Zirconate Compounds Certain zirconium compounds are used in this invention.

Examples of the organic zirconate compound include an organic zirconate compound represented by the following formula and a zirconium acylate polymer (described later).

(RO) Z r (OR' ) 4-8 (wherein, RO is an easily hydrolyzable organic group, OR' is an organic group that is hardly hydrolyzable and exhibits lipophilicity, and X is an integer of 1 to 3. The organic zirconate compound represented by the above formula has both an organic group that is easily hydrolyzed and an organic group that is difficult to be hydrolyzed and exhibits lipophilicity.

Specific such compounds include, for example, isopropyltriisostearoylzirconate, n-butyltriisostearoylzirconate, isopropyltrioleylzirconate, n-butyltrioleylzirconate, n-butyl(diisostearoyl)oleyl. Zirconate, Isopropyl tridodecylbenzenesulfonyl zirconate, Isopropyl tris(dioctylpyrophosphate) zirconate, Tetraisopropylbis(
dioctyl phosphate) zirconate, tetraoctyl bis(ditridecyl phosphite) zirconate, tetra(2,2-diallyloxymethyl-1-butyl) bis(di-tridecyl) phosphite zirconate, bis(dioctyl pyrophosphate) ethylene zirconate , isopropyl dimethacrylic isostearoyl zirconate, isopropyl isostearoyl diacryl zirconate, isopropyl tri(dioctyl phosphate) zirconate, isopropyl tricumylphenyl zirconate, isopropyl tri(N-aminoethyl-aminoethyl) zirconate, dicumylphenyloxyacetate zirconate nate, diisostearoylethylene zirconate, bis(dioctylpyrophosphate)oxyacetate zirconate, isopropyltrioctanoylzirconate, n-butyltriisostearoylzirconate, isobutyltriisostearoylzirconate, tert-butyltriisostearoylzirconate ester, isopropyltrioleyl zirconate, isobutyltrioleyl zirconate, and isobutyl (diisostearoyl) oleyl zirconate.

In this invention, the amount of the organic zirconate compound used is 0.01 to 15% by weight, preferably 0.05 to 10% by weight, based on the weight of the coating composition excluding the solvent. This is because when the amount is less than 0.05% by weight, the dispersibility of the powder in the paint and coating film gradually begins to decrease, and when it is less than 0.01% by weight, this tendency becomes remarkable, causing agglomeration of the copper powder and environmental resistance. If the content exceeds 10% by weight, an excessive hydrophobic film will be formed on the surface of the copper powder, gradually impeding conductivity, and if the content exceeds 15% by weight, this tendency will become significant.

The organic zirconate compound may contain by-products during its synthesis, such as higher fatty acid esters and alcohols. Zirconium acylate polymer One embodiment of the organic zirconate compound used in the present invention is a zirconium acylate polymer.

This zirconium acylate polymer is specified as follows. That is, a zirconium acylate polymer has an easily hydrolyzable alkoxy group bonded to a zirconium atom in the main chain (-Zr-0) and a hardly hydrolyzable and lipophilic acylate group also bonded to a zirconium atom. It is.

This zirconium acylate polymer has tetraalkoxyzirconium Z r (OR) 4 with carboxylic acid,
It can be obtained by reacting with acid anhydrides, inorganic acids, etc., or by reacting tetrachlorozirconium Z r (CI) 4 with ammonia/carboxylic acid, carboxylic acid sodium salt, etc.

A preferred method for synthesizing a zirconium acylate polymer is a method in which tetraalkoxyzirconium Z r (OR)4 is reacted with several times the molar amount of a carboxylic acid, particularly a higher fatty acid.

A method for preparing tetraalkoxyzirconium Z r (OR) 4 from several times the molar amount of carboxylic acid or an isomer thereof includes, for example, tetra-n-butoxyzirconium,
1 mol or more, preferably 3 to 6 mol, of stearic acid, palmitic acid, mystylic acid, lauric acid, capric acid, etc. per 1 mol of tetra-t-butoxyzirconium, tetra-n-butoxyzirconium, tetraisobutoxyzirconium. higher saturated fatty acids and their isomers,
It consists of the action of higher unsaturated fatty acids such as oleic acid, linoleic acid, and lyluic acid and their isomers.

Separation and purification of the synthesized zirconium acylate polymer can be performed by methods such as distillation, extraction, recrystallization, and column chromatography.

Higher carboxylic acid ester In this invention, the higher carboxylic acid ester used together with the zirconium acylate polymer has a long chain of many carbons, and preferable esters include higher fatty acid acylate groups and easily hydrolyzable alkoxy There is something that consists of the base.

The portion of this ester that corresponds to a higher carboxylic acid is a higher fatty acid acylate group having 8 to 24 carbon atoms, and the portion of this ester that corresponds to an alcohol has 1 to 15 carbon atoms,
Preferably it is an alkoxy group having 1 to 10 carbon atoms.

Specific examples of such higher carboxylic acid esters include higher saturated fatty acids such as stearate, valmitate, mystilate, laurate, and caprate, and their isomers, oleate, and linoleate. , higher unsaturated fatty acids such as linoleic acid esters, and their isomers. This is because if the carboxylic acid ester used is of a lower grade, the hydrophobicity of the carboxylic acid ester film formed on the surface of the copper powder will be impaired, and the good dispersion state of the copper powder will not be achieved when forming paints and coatings with the resin binder. Because you can't get it.

Higher carboxylic acid esters that can be used in the present invention can be obtained by reacting alcohol with higher carboxylic acids during boat fishing, or esters that are by-produced when synthesizing zirconium acylate polymers can be used. .

When a mixture of a zirconium acylate polymer and a higher carboxylic acid ester is obtained from a reaction mixture of tetraalkoxyzirconium and a higher carboxylic acid, 1 mole of tetraalkoxyzirconium and 2 to 8 moles of higher carboxylic acid, preferably 1 mole of tetraalkoxyzirconium. and higher carboxylic acid in a ratio of 3 to 6 moles. If the amount is less than this range, mere acylates, such as monoacylates and zirconium alkoxy polymers will be produced, and no zirconium acylate polymer will be produced; if the amount is more than this range, zirconium acylate polymers will be quantitatively obtained, but only as by-products. This is because certain carboxylic acid esters and alcohols increase excessively. The alkoxy group of the tetraalkoxyzirconium used here has 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms. This is because when the number of carbon atoms exceeds 10, the hydrolysis reaction with water adsorbed on the surface of the copper powder does not proceed quickly, and the reactivity of forming acylate with carboxylic acid decreases, and when the number of carbon atoms exceeds 15, the reactivity becomes significant. This is because the reaction rate will decrease and the reaction will hardly proceed.

Conductive Coating Composition The conductive coating composition of the first aspect of the present invention contains carbon powder as a reducing agent, copper powder coated with an organic zirconate compound, a resin binder, and a solvent.

In another aspect, the conductive coating composition of the present invention is
An organic zirconate compound is added to a mixed system of copper powder, carbon powder as a reducing agent, a resin binder, and a solvent.

The resin binder that can be used in the present invention is a thermosetting or thermoplastic resin that has good adhesion to plastics commonly used in electronic devices. For example, in contrast to plastics for electronic device housings such as ABS, polystyrene, and PP01 polycarbonate, acrylic resins, polyurethane resins, polyester resins, styrene resins, phenolic resins, epoxy resins, and mixed resins thereof, etc. can be used.

The blending amount of the resin binder is 5 to 60% by weight, preferably 10 to 40% by weight, based on the total weight of the copper powder and carbon powder. This is because if it is less than 10% by weight, it becomes gradually difficult to form a coating, and if it is less than 5% by weight, it is impossible to form a coating, and if it exceeds 40% by weight, the conductivity of the coating decreases. This is because when the weight exceeds 60% by weight, this tendency becomes remarkable.

In addition, solvents that can be used in this invention include those having excellent compatibility with the resin binder and various additives, such as hydrocarbons such as toluene, hexane, and xylene, methyl alcohol, and ethyl alcohol. ,
Alcohols such as propyl alcohol and butyl alcohol, Kents such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, and ethers such as methyl calpitol, ethyl carpitol, 'methyl cellosolve, and ethyl cellosolve. One type of organic solvent or a mixture of two or more types is preferable. It is desirable that these selections be made in consideration of workability such as coating and the object to be coated.

In addition to the above components, various additives can be included depending on the purpose. Such agents include reducing agents, surfactants, antisettling agents, antifoaming agents, thickeners, thixotropic agents, rust preventives, and flame retardants.

[For production]

In this invention having the above-described configuration, carbon powder is blended into the coating composition.

The copper powder in the paint is oxidized by oxygen dissolved in the paint composition or permeated from the surface of the paint film, causing patina and the like to occur on the paint film. The carbon powder blended into the paint composition is
Captures oxidizing substances such as oxygen and acts as a reducing agent, preventing copper powder from oxidizing.

On the other hand, organic zirconate compounds have a hydrophilic organic group centered on the zirconium atom that is easily hydrolyzed and a lipophilic organic group that is difficult to hydrolyze. A displacement reaction occurs with the adsorbed water on the surface of the copper powder.

Therefore, the lipophilic organic groups are arranged on the outside of the copper powder surface, forming a hydrophobic film of the organic zirconate compound.

In an embodiment using a mixture of a zirconium acylate polymer and a higher carboxylic acid ester, the zirconium acylate polymer has an easily hydrolyzable alkoxy group and a hydrolyzable and lipophilic acylate group. The groups react with the adsorbed water on the coating, while the lipophilic acylate group portions are oriented to the outside of the copper powder. This lipophilic acylate group film acts as a hydrophobic film with the copper powder, and furthermore, this lipophilic acylate group part acts as a hydrophobic film with the resin binder molecules due to van der Waals forces, hydrogen bonds, etc. in the conductive composition. Copper powder is skillfully intertwined with ionic bonds, covalent bonds, etc., and forms a good dispersion state of copper powder in paints and coatings by stirring, shear stress during the cross-wire process, etc.

A hydrophobic film of zirconium acylate polymer covers the surface of the copper powder, but it cannot completely cover the surface of the copper powder.
Gaps and cracks occur in the membrane. Higher carboxylic acid esters have easily hydrolyzable alkoxy groups, so they undergo a transesterification reaction with adsorbed water on the surface of copper powder, bind to the surface of copper powder through electrostatic approach, and are transesterified by the lipophilic acylate group. , a hydrophobic film of carboxylic acid ester is formed in the gap to form a dense film on the surface of the copper powder.

Therefore, in an embodiment in which a mixture of a zirconium acylate polymer and a higher carboxylic acid ester is coated, since the mixture of the zirconium acylate polymer and a higher carboxylic acid ester is coated, it does not react with the adsorbed water on the surface of the copper powder or the coating. A strong film that does not impair conductivity can be formed by electrostatic approach or the like.

〔Effect of the invention〕

This invention provides the following effects.

The conductive coating composition according to claim 1 eliminates the drawbacks of conventional conductive coatings and improves the environmental resistance, especially salt water resistance, of the coating composition without deteriorating its conductive performance. I can do it. That is, even under severe conditions such as salt spray, the generation of patina in the coating film is suppressed, the conductivity is maintained over a long period of time, and excellent environmental resistance and salt spray resistance are improved.

In addition, since organic zirconate compounds are used17,
The dispersibility of copper powder and carbon powder in the resin binder can be improved, and the heat resistance and moisture resistance can be improved and maintained for a long time.

〔Example〕

This invention will be specifically explained by the following examples.

Experimental Material A: Copper Powder A dendritic electrolytic copper powder (manufactured by Mitsui Mining & Smelting Co., Ltd., MF-D2) shown in Table 1 was used.

Table 1 Apparent Density 0.8-1. 1g/am3 specific surface area 0.40g/g average particle size
8.0 μm Purity >99.2% by weight HNO3 insoluble content <0.03% by weight Loss on reduction <0.80% by weight b. Resin binder Table 2 shows the resin binder used in the experiment.

Table 2 Type Product name Acrylic resin Acrybond BC-415B Phenolic resin PL-2210 C1 Organic zirconate compounds Table 3 shows the organic zirconate compounds used in this experiment.

No.

Table 3 Organic zirconate compounds Quaisopropyltriisostearoylzirconate n-Butyltriisostearoylzirconate Isopropyltrioleylzirconate n-Butyltrioleylzilphnate n-Butyl(diisostearoyl)oleylzirconate Isopropyltridodecylbenzenesulfonyl Zirconate isopropyl dimethacrylylisostearoyl zirconate dicumylphenyloxyacetate zirconate isopropyl tricumylphenyl zirconate bis(dioctylpyrophosphate) oxyacetate zirconate d. Fine carbon powder The carbon powder used in this experiment (Toka Black #5500
, Tokai Carbon Co., Ltd.) are shown in Table 4.

Table 4 Calculated average particle diameter 25 nnNitrogen adsorption specific surface area 206 7 g, H
5. 8 fluorescein (149μm
)Residue 0.0010% by weight Sieve (44μm) residue
0.0016% by weight Apparent density 0.
245g/am3e. Comparative Dispersants For comparison purposes, the comparative sample dispersants in Table 5 below were used.

Table 5 No. Comparative dispersant 6-1 Isopropyl tridodecylbenzenesulfonyl titanate 6-2 Tetraisopropyl bis(dioctyl phosphate) titanate 6-3 Acetalkoxyaluminum diisopropylate 6-4 Anthrazine 6-5 7-methacryloxypropyltrimethoxysilane 6-6 Oleic acid experimental example 1 Conductivity of conductive paint Copper powder from Table 1, resin binder from Table 2, fine carbon powder from Table 4, organic zirconate compound from Table 3, and solvent (as a resin binder) In the case of acrylic resin (Acrybond BC-415B, manufactured by Mitsubishi Rayon), toluene, phenolic resin (solid content 60% by weight, Gunei Chemical (manufactured by
A conductive paint was prepared using a conventional method using methylcarpitol (manufactured by Co., Ltd.). The obtained conductive paint was printed on an acrylic board (when using acrylic resin as the resin binder) or a phenol board (when using phenolic resin as the resin binder) using a screen printing machine.
A conductive circuit with a width of 0.1 cm and a film thickness of 4°±10 μm was formed and dried at 50° C. for 30 minutes or at 150° C. for 30 minutes. The volume resistivity of the cured circuit (coating Jli) was measured.

The amount of fine carbon powder added is 0.1 to the weight of copper powder.
, 5, 10, 30, and 50% by weight, and the amount of resin binder added is 10% by weight based on the weight of the coating composition excluding the solvent.
The content of the organic zirconate compound is 0.05% by weight based on the weight of the coating composition excluding the solvent.
, 1. o13.0, 5.0, 10.0% by weight.

As a result, the coating film of the conductive paint according to the present invention is approximately 3×1
It had a volume resistivity of 0 to 9×10 Ω.

On the other hand, for comparison, a conductive paint was prepared in the same manner as above except that the fine carbon powder shown in Table 4 was not used, and the volume resistivity of the paint film was measured.

As a result, the coating film of the comparative conductive paint was approximately 3 x 10-4 ~
It had a volume resistivity of 9×10 −4 Ω·mark. This shows that the addition of fine carbon powder has no adverse effects such as a decrease in conductivity.

Furthermore, for comparison, a conductive paint was prepared in the same manner as above, except that the comparative dispersant shown in Table 5 was used instead of the organic zirconate compound shown in Table 3, and the volume resistivity of the paint film was measured.

As a result, the comparative conductive paint film did not exhibit uniform conductivity, and had a slightly inferior volume resistivity of approximately 8×10′ to 3×10 −3 Ω·cm. From this, the addition of organic zirconate compounds provides excellent dispersibility,
Copper powder and carbon powder of different types and sizes can be uniformly dispersed.

Experimental Example 2 Salt Water Resistance A conductive paint film (conductor circuit) substrate prepared in the same manner as in Experimental Example 1 was coated with a 5% by weight NaCl aqueous solution (liquid temperature 35±2
A salt water spray test was conducted for 72 hours using a 72-hour (°C) temperature, and the generation of patina and the rate of change in resistance (%) of the coating film were determined by aFI.

As a result, the coating film of the conductive paint prepared according to the present invention showed no discoloration and no patina. Also,
The conductive paint film is 4X10'~9X10'Ω・(1)
It had a volume resistivity of , which was almost unchanged from the initial value.

On the other hand, the coating film of the comparative conductive paint containing the comparative dispersant changed color to brownish-brown and developed a severe patina. Moreover, the coating film of the conductive paint had a volume resistivity of 2X10' to 1X10-2 Ω·cm.

From the above results, it was found that the coating film of the conductive paint prepared according to the present invention has excellent salt water spray resistance.

Experimental Example 3 Heat-resistant, moisture-resistant, and aging properties of the coating film A conductive paint coating (conductor circuit) substrate prepared in the same manner as in Experimental Example 1 was
1 at a high temperature of 85°C and a humidity environment of 60°C/95% RH.
After being left for 350 hours, the resistance change rate (%) of the coating film was 1111.
Established.

As a result, most of the conductive paint films prepared and formed according to the present invention are approximately 6X
It had a volume resistivity of 10' to lXl0-3Ω·(up to), and the rate of change was small. In addition, in a humidity environment of 60℃/95%RH, most of the
It had a volume resistivity of -'Ω· and the rate of change was small.

On the other hand, most of the conductive paint films from comparative samples that do not contain fine carbon powder have a volume resistivity of approximately 6X10' to 1X10-''Ω· in a high-temperature environment of 85°C. The rate of change was relatively small.
Even in a humidity environment of 5% RH, most of the
It had a volume resistivity of ˜9×10 −′Ω·, and the rate of change was relatively small.

In addition, most conductive paint films from comparative samples containing comparative dispersants were approximately 3×1 in a high temperature environment of 85°C.
It had a volume resistivity of 0-3 to 8 x 10-"Ω・(7), and exhibited a volume resistivity of not a little 1×10-2Ω・(to), and the rate of change was large. Also, at 60°C/95 %RH
Even in a humidity environment of 2 x 10 to 5 x 10
It has a volume resistivity of -3Ω and is not less than 1x10
It exhibited a volume resistivity of -2 Ω·am, and the rate of change was large.

From these results, it can be seen that the coating film of the conductive paint prepared according to the present invention is extremely excellent in heat resistance and moisture aging resistance.

Claims (3)

[Claims] 1. A conductive coating composition comprising copper powder, an organic zirconate compound, a reducing agent consisting of carbon powder, a resin binder, and a solvent. 2. The conductive coating composition according to claim 1, wherein the carbon powder is a fine carbon powder having a number average particle size of 5 μm or less. 3. The content of fine carbon powder is 0.1 to 0.1 to the weight of copper powder.
3. The conductive coating composition according to claim 2, wherein the amount is 50% by weight.