JPH083486A - Water-based conductive coating material - Google Patents

Abstract

PURPOSE:To provide a safe water-based conductive coating material reduced in deterioration of conductivity and being excellent in storage stability. CONSTITUTION:This material is one prepared by dispersing an electrolytic copper powder having a specific surface area of 2000-10000cm<2>/g as determined by the BET method, a content of particles passing a 44mum sieve of 90wt.% or above and an oxygen content of 0.2wt.% or below or a copper powder formed by dis-integratring the above hydrolytic copper powder in a water-based polyurethane resin essentially consisting of an organic poly-isocyanate compound and a carboxylic polyol compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous conductive coating material prepared by mixing and dispersing electrolytic copper powder.

[Prior art]

As is well known, in order to prevent the leakage of unnecessary electromagnetic waves generated from computer equipment and the like, a method of applying a conductive paint to a plastic housing accommodating the equipment or the like is adopted, and this method is economical. It is widely used because of its advantage.

As the conductive paint, a paint using nickel powder has been mainly used. However, improvement and research have progressed from a paint using the nickel powder to a paint using copper powder. Has been adopted. As a concrete improvement example of a coating using copper powder, an organic phosphorus compound (Japanese Patent Laid-Open No. 58-145) is disclosed.
769) and phosphonic acids (JP-A-60-2317).
72), phosphorous acid esters (JP-A-60-229).
966), an organic titanate compound (JP-A-56-
No. 36553 gazette) is added.

[0004]

Since all of the above-mentioned conventional conductive paints are oil-based paints using an organic solvent, there is a risk of ignition and explosion during coating, and the water-based conductive paint is also used for improving the working environment. Development is desired.

However, since water-based paints use water as a solvent instead of an organic solvent, when copper powder is mixed and dispersed, the surface of the copper powder is oxidized in a very short time, and conductivity cannot be obtained. Even in the acidity test, the conductivity of the coating film deteriorates rapidly and it cannot be used, and the storage stability of the paint is poor. However, there is a problem in that the paint may thicken and gelate.

[0006] Further, even if the above-mentioned additives proposed as improvements for oil-based paints are applied to water-based paints, the effect is poor. In addition, a method of adding an aliphatic amine for water-based paints (JP-A-5-247383). Japanese Patent Publication No.) has also been proposed, but it was not a practically satisfactory paint.

Therefore, it is a technical object of the present invention to provide a safe water-based conductive coating material which has little deterioration in conductivity, is excellent in storage stability, and is safe.

In order to achieve the above technical problems, the present inventors prepared a large number of water-based conductive paints by combining various copper powders and various water-based resins, and conducted a trial-and-error test / research to investigate the characteristics. As a result, by combining a specific water-based emulsion and a specific electrolytic copper powder, excellent initial conductivity is shown, and there is little deterioration in conductivity after an environmental reliability test, which is an obstacle to practical application. The storage stability of the conventional paint can be remarkably improved, and a practical water-based conductive paint has been developed.

[0009]

A water-based conductive coating material according to the present invention comprises an aqueous polyurethane resin containing an organic polyisocyanate compound and a polyol compound having a carboxyl group as essential components and having a specific surface area value of 2000 cm ² by BET method.
/ G ~ 10000 cm ² / g, 90% by weight or more of which passes through a 44 μm sieve and has an oxygen content of 0.2% by weight or less, or a mixture of copper powder obtained by crushing the electrolytic copper powder. is there. Further, according to the present invention, in the above water-based conductive coating material, the glass transition point (Tg) of the water-based polyurethane resin is 25 to 150 ° C. Further, according to the present invention, in the above water-based conductive paint, the average particle size of the emulsion of the water-based polyurethane resin is 20 nm to 200 nm. Further, in the present invention, in the above water-based conductive coating material, the content of the organic solvent in the water-based polyurethane resin is 5% or less.

The structure of the present invention will be described in detail below. The aqueous polyurethane resin (hereinafter, also referred to as “PUD”) used in the present invention is an emulsion in which a polyurethane resin containing an organic polyisocyanate compound and a polyol compound having a carboxyl group as essential components is dispersed in water. That is, the emulsion, in the presence or absence of an organic solvent, an organic polyisocyanate compound, a polyol compound having a carboxyl group and a carboxyl group-containing urethane prepolymer obtained from polyols, in the presence of water, It is a urethane resin dispersed in water obtained by reacting with a basic organic compound and an extender. Even if a polyurethane resin other than the water-based polyurethane resin or other emulsion such as acrylic, vinyl acetate, styrene-butadiene copolymer, vinyl chloride, ethylene vinyl acetate copolymer is used, the copper powder reacts with the resin, so that good conductivity is obtained. It is not possible to obtain a protective coating film.

Examples of the organic polyisocyanate include aliphatic, alicyclic, araliphatic and aromatic polyisocyanates. Specific examples thereof are shown below. Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3- Butylene diisocyanate, 2,4
4-or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate, lysine ester triisocyanate, 1,4
8-triisocyanate octane, 1,6,11-triisocyanate undecane, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-
Examples include triisocyanate hexane, 2,5,7-trimethyl-1,8-diisocyanate-5-isocyanatomethyloctane, and the like.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate and 1,4
-Cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-
3,5,5-Trimethylcyclohexyl isocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,4- or 1,3-bis ( Isocyanatomethyl) cyclohexane, 1,3,5-triisocyanate cyclohexane, 1,3,5-trimethylisocyanate cyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2. 1) Heptane, 2- (3-isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo (2.2.1) heptane and the like can be mentioned.

As the araliphatic polyisocyanate,
For example, 1,3,5-triisocyanate methylbenzene, 1,3- or 1,4-xylylene diisocyanate, or a mixture thereof, ω, ω′-diisocyanate-1,4-diethylbenzene 1,3- or 1,4 -Bis (1-isocyanate-1-methylethyl) benzene,
Or the mixture etc. can be mentioned.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate and 4,4 '.
-Diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, triphenylmethane-4,4 ',
4 ''-triisocyanate, 1,3,5-triisocyanate benzene, 2,4,6-triisocyanate toluene, 4,4'-diphenylmethane-2,2 ', 5
5'-tetraisocyanate etc. can be mentioned.

As the carboxyl group-containing polyol compound, any one can be used as long as it can impart a branched carboxyl group to a linear prepolymer molecule, but it is easy to control the carboxyl group content. Those having a molecular weight are preferable, and examples thereof include 2,2-dimethylolpropionic acid.

As the polyols, known polyols used for the production of ordinary polyurethane resins,
For example, ethylene glycol, propanediol, 1,
4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,6-hexanediol, neopentyl glycol, alkane (7 to 2
2) diol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanedimethanol, alkane-1,2-diol (C17-2
0), hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, 2,6-dimethyl-1-octene-3,
8-diol, bisphenol A glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, 1,1,1 −
Tris (hydroxymethyl) propane, 2,2-bis (hydroxymethyl) -3-butanol and other aliphatic triols (C8-24) tetramethylolmethane, D-sorbitol, xylitol, D-mannitol, D-mannitol, etc. And low molecular weight polyols, polyethylene glycol, polypropylene glycol, polyester polyol, polycaprolactone polyol, polytetramethylene ether polyol, polycarbonate polyol, polythioether polyol, polyacetal polyol, polybutadiene polyol, and other macropolyols. A resin can be designed by appropriately selecting these polyols according to the required physical properties such as hardness and softness.

As the organic solvent which can be used in the production of the urethane prepolymer, hydrocarbons such as toluene and xylene which have no reactivity with isocyanate groups, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, Esters such as ethyl acetate, butyl acetate and 1-methoxy-2-propyl acetate, diethyl ether, tetrahydrofuran and 1,4
-Ethers such as dioxane, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide and the like can be mentioned. From the viewpoint of storage stability after dispersion of copper powder, it is preferable that the final coating material does not substantially contain an organic solvent, and it is necessary to remove the solvent after the emulsification / extension reaction. Therefore, a solvent having a low boiling point such as acetone, methyl ethyl ketone, or ethyl acetate is particularly preferable.

The amount of organic solvent contained in the final paint is 5%
It is preferably at most, and more preferably at most 1%. When the amount of organic solvent contained in the final paint is 5% or more, the storage stability of the copper paint in which the copper powder is dispersed becomes poor,
During storage, the paint thickens and becomes unusable, and the conductivity of the coating film deteriorates.

PUD, which is one of the constituents of the water-based conductive coating material according to the present invention, is prepared by dissolving or emulsifying the above-mentioned carboxyl group-containing urethane prepolymer in water in the presence of a basic organic compound, and adding a stretching agent (described later). Drop it, or
The basic organic compound and the elongation agent are dissolved in water and the urethane prepolymer solution is added dropwise to impart hydrophilicity to the carboxyl group-containing urethane prepolymer, and at the same time, the elongation reaction is performed, and then dehydration is performed under reduced pressure. -Can be produced by removing the solvent.

As the extender to be dropped, water or polyamines are suitable. For example, ethylenediamine, diethylenetriamine, triethylenetetramine, propylenediamine, butylenediamine, hexamethylenediamine, cyclohexylenediamine, piperazine, phenylenediamine, tolylenediamine. Amine, xylylenediamine,
Bis- (4-aminophenyl) methane, bis- (4-amino-3-chlorophenyl) methane, diaminomethylcyclohexane, 1-amino-3-aminomethyl-3.
5.5-Trimethylcyclohexane, hydrazine, 2-
Examples thereof include hydroxyethylhydrazine.

As the basic organic compound which reacts with the carboxyl group to impart hydrophilicity, known compounds can be used, particularly triethylamine, dimethylethanolamine, dimethylpropylamine, ammonia, diethylethanolamine and the like. Is preferred.

The glass transition point (Tg) of the PUD obtained as described above may be 0 ° C. or higher, preferably 25 to 150 ° C., more preferably 50 to 100 ° C. If the glass transition point (Tg) is lower than room temperature, the wet heat resistance of the coating film is poor and it becomes difficult to maintain the conductivity, and if it is 150 ° C or higher, the film forming property is poor and the desired initial conductivity cannot be obtained.

The average particle size of PUD is 200 nm or less,
It is preferably 100 nm or less. When the average particle size is larger than 200 nm, the uniformity of the copper powder-containing coating film is impaired, and the initial conductivity and the conductivity after the moist heat resistance test deteriorate. In addition,
The lower limit of the particle size is usually about 20 nm due to manufacturing technology restrictions.

As the copper powder used as the conductive material in the present invention, electrolytic copper powder produced by an aqueous solution electrolysis method or copper powder obtained by crushing electrolytic copper powder is suitable. Good results cannot be obtained by using flaky copper powder produced by the mechanical grinding method or atomized copper powder produced by the atomization method. Electrolytic copper powder or copper powder obtained by crushing electrolytic copper powder is B
It is necessary that the specific surface area value by the ET method is 2000 cm ² / g or more. Specific surface area value by BET method is 2000 cm ² /
If it is more than g, the particle shape is dendritic, and it is easy for the copper powders to come into contact with each other, and conductivity is easily obtained, but the electrolytic copper powder with a small specific surface area value has a particle shape close to a sphere, so a coating with good conductivity. Can't get Note that the upper limit of the specific surface area value is usually about 10000 cm ² / g due to manufacturing technology restrictions.

The method of crushing the electrolytic copper powder is more preferable than the method of using a crusher in which the particle shape after crushing is spherical or flaky.
It is preferable to use a method of cutting a dendritic branch portion such as a pin mill or a jet mill.

Further, in order to prevent clogging of the spray nozzle in spray coating and to prevent copper powder from peeling off from the coating film surface, the particle size of the electrolytic copper powder or the copper powder obtained by crushing the electrolytic copper powder is 44 μm.
It must pass through 90 m by weight or more of the m sieve.

In order to obtain an excellent conductive coating film, it is important that the oxygen content of the electrolytic copper powder or the copper powder obtained by crushing the electrolytic copper powder is 0.2% by weight or less. The smaller the oxygen content of the copper powder, the better the conductivity tends to be obtained. When the oxygen content of the copper powder is 0.2% by weight or more, it becomes difficult to obtain an excellent conductive coating film.

The copper powder satisfying the above powder characteristics can be obtained by the method already developed by the present inventors and disclosed in Japanese Patent Publication No. 1-39693.

The amount of copper powder is 20% of the polymer solid content in the emulsion.
It is preferable to mix and disperse 70 to 80 parts by weight with respect to 30 parts by weight.

By the way, in the water-based conductive paint according to the present invention, various kinds of pigments, thickeners, plasticizers, film-forming aids, defoaming agents, antioxidants and the like which are usually used in general water-based paints are used. Additives can be added.

[0031]

In the present invention, as the aqueous emulsion used as the binder, an aqueous polyurethane resin containing an organic polyisocyanate compound and a polyol compound having a carboxyl group as essential components is adopted, and copper powder is mixed and dispersed in the aqueous polyurethane resin. Therefore, it becomes difficult for the resin and the copper powder to react with each other, and the specific surface area value of the copper powder as the conductive material by the BET method is 2000 cm ² / g or more, and the electrolytic copper powder or the electrolytic copper powder is crushed. Particle size of copper powder is 44μ
Assuming that 90% by weight or more has passed through the m sieve, the oxygen content is 0.2
Since the content is less than or equal to wt%, it is possible to prevent clogging of the spray nozzle at the time of spray coating and peeling of copper powder from the coating surface, and the particle shape exhibits a dendritic shape which is a characteristic of the electrolytic method. Since the powders come into contact with each other easily, an excellent conductive coating film can be easily formed, and an aqueous conductive coating material having excellent storage stability can be obtained. In the present invention, the glass transition point of the polyurethane resin is set to 25 to 150 ° C., and the emulsion average particle size of the water-based polyurethane resin is set to 200 nm or less. By setting the content to 5% or less, a dense copper powder-containing coating film can be formed, and an aqueous conductive paint having excellent initial conductivity and environmental stability reliability testability and excellent storage stability can be obtained. .

[0032]

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited thereby. Example 1. 1000 ml equipped with thermometer, stirrer, and nitrogen introduction tube
In a 4-necked flask, 250 g of polycaprolactone diol with a molecular weight of 1000, 26 g of neopentyl glycol, 4.5 g of trimethylolpropane, 26.8 of dimethylolpropionic acid were placed.
g, acetone 227 g, 3-isocyanatomethyl-3,
5,5-Trimethylcyclohexyl isocyanate 222.
After charging 2 g and maintaining the internal temperature at 55 to 60 ° C. under nitrogen flow for 10 hours, a urethane prepolymer having an NCO group content of 2.7% was obtained. Next, 1000g of deionized water containing 20.2g of triethylamine and 15g of ethylenediamine is added at 40 ° C.
Then, 756.5 g of the above prepolymer was added dropwise while stirring and mixing with a lab mixer, and a reaction was carried out to obtain an aqueous polyurethane resin. This aqueous resin solution is further
De-acetone depressurization was performed at 50 ° C, and the final nonvolatile content was 35.5.
%, PH 8.0, and a viscosity of 120 cps / 25 ° C., an aqueous polyurethane resin solution was obtained.

The polyurethane resin thus obtained has a glass transition point of 65 ° C., an average particle diameter of the emulsion is 50 nm,
The organic solvent content was 1% or less.

To 100 g of this aqueous polyurethane resin solution, B
Specific surface area value by ET method 3000 cm ² / g, a 44μm sieve 99
%, And 100 g of electrolytic copper powder having an oxygen content of 0.12% was mixed and dispersed to produce an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive coating material thus produced, the coating material was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial conductivity of the coating film of the water-based conductive paint of this example was 0.8 × 10 ⁻³ Ω · cm, which showed the same excellent conductive performance as the conventional oil-based copper-based conductive paint. Further, the formed coating film was left for 1000 hours in a 60 ° C., 95% RH humidity atmosphere, and as a result, the conductivity was 1.2 × 10 ⁻³ Ω · cm, which was little deterioration. In addition, the water-based conductive paint produced was kept at room temperature for 25
After being left at ℃, paint was applied on the phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.
10 ^- and ^{3 Ω} · cm, were almost same conductivity performance as the initial conductivity.

Example 2. In a 1000 ml four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 250 g of a polycarbonate diol having a molecular weight of 1000 and neopentyl glycol 20.
Charge 8g, trimethylolpropane 4.5g, dimethylolpropionic acid 33.5g, acetone 216g, 1,3-bis (isocyanatomethyl) cyclohexane 194.2g, and keep the internal temperature at 55-60 ° C under nitrogen flow for 7 hours reaction. After doing
A urethane prepolymer having an NCO group content of 2.9% was obtained.
Next, 25.2 g of triethylamine and 7.5 of ethylenediamine
g, deionized water containing hydrazine monohydrate 6.2 g 120
While maintaining 0 g at 40 ° C. while stirring and mixing with a lab mixer, 718 g of the above prepolymer was dropped and reacted to obtain a water-based polyurethane resin. This aqueous resin solution,
Further, deacetonization under reduced pressure was carried out at 50 ° C. to finally obtain an aqueous polyurethane resin solution having a nonvolatile content of 36.1%, pH 8.2, and a viscosity of 210 cps / 25 ° C.

The glass transition point of the polyurethane resin thus obtained is 73 ° C., the average particle size of the emulsion is 50 nm,
The organic solvent content was 1% or less.

To 100 g of this aqueous polyurethane resin solution, 100 g of the same electrolytic copper powder as that used in Example 1 was mixed and dispersed to produce an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive coating material thus produced, the coating material was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial conductivity of the coating film of the water-based conductive paint of this example was 0.8 × 10 ⁻³ Ω · cm, which was the same excellent conductivity performance as the conventional oil-based copper-based conductive paint. Further, the formed coating film was left for 1000 hours in a 60 ° C., 95% RH humidity atmosphere, and as a result, the conductivity was 1.2 × 10 ⁻³ Ω · cm, which was little deterioration. In addition, the water-based conductive paint produced was kept at room temperature for 25
After being left at ℃, paint was applied on the phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.
10 ^- and ^{3 Ω} · cm, were almost same conductivity performance as the initial conductivity.

Example 3. In a 1000 ml four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, Takelac U-5610
(Takeda Pharmaceutical Co., Ltd. polyester polyol, molecular weight 1000) 200 g, neopentyl glycol 26 g, trimethylol propane 2.2 g, dimethylol propionic acid 36.
After charging 8g, 197g of acetone and 194.2g of 1,3-bis (isocyanatomethyl) cyclohexane, keeping the internal temperature at 55-60 ° C under nitrogen stream for 7 hours, urethane with NCO group content 3.2% A prepolymer was obtained. Next, 24.1 g of dimethylethanolamine and hydrazine monohydrate 1
656.2 g of the above prepolymer while stirring and mixing 1000 g of deionized water containing 2.5 g at 40 ° C with a lab mixer
Was dropped and reacted to obtain an aqueous polyurethane resin. This water-based resin solution was further subjected to vacuum deacetoneation at 50 ° C, and finally the nonvolatile content was 37.1%, pH 8.0, and viscosity.
An aqueous polyurethane resin solution of 470 cps / 25 ° C was obtained.

The polyurethane resin thus obtained has a glass transition point of 90 ° C., an average particle diameter of the emulsion of 50 nm,
The organic solvent content was 1% or less.

To 100 g of this aqueous polyurethane resin solution, 100 g of the same electrolytic copper powder as that used in Example 1 was mixed and dispersed to produce an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive coating material thus produced, the coating material was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial conductivity of the coating film of the water-based conductive paint of this example was 0.8 × 10 ⁻³ Ω · cm, which was the same excellent conductivity performance as the conventional oil-based copper-based conductive paint. Further, the formed coating film was left for 1000 hours in a 60 ° C., 95% RH humidity atmosphere, and as a result, the conductivity was 1.2 × 10 ⁻³ Ω · cm, which was little deterioration. After standing the aqueous conductive paint prepared in 1 month at room temperature 25 ° C., the paint is applied on the phenol substrate, room temperature for 24 hours left result of forming a coating film of 70μm to, 0.9 × 10 ^{- 3} Ω
・ Cm showed almost the same conductivity as the initial conductivity.

Example 4. In a 1000 ml four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, Takelac U-2610
(Takeda Pharmaceutical Co., Ltd. polyester polyol, molecular weight 1000) 300 g, neopentyl glycol 20.8 g, trimethylol propane 4.5 g, dimethylol propionic acid 2
After charging 6.8 g, 256 g of acetone, 244.4 g of tetramethylxylylene diisocyanate, 0.05 g of dibutyltin dilaurate and keeping the internal temperature at 55-60 ° C under a nitrogen stream for 6 hours to carry out the reaction for 6 hours, the NCO group content is 2.4%. A urethane prepolymer of was obtained. Then, deionized water containing 20.2 g of triethylamine and 19.0 g of 2-hydroxyethylhydrazine 12
While keeping 00 g at 40 ° C., 852.5 g of the above prepolymer was added dropwise while mixing and stirring with a lab mixer, and a reaction was carried out to obtain an aqueous polyurethane resin. The water-based resin solution was further deaerated under reduced pressure at 50 ° C. to finally obtain a water-based polyurethane resin solution having a nonvolatile content of 35.0%, pH 7.7 and a viscosity of 90 cps / 25 ° C.

The polyurethane resin thus obtained has a glass transition point of 41 ° C. and an emulsion having an average particle diameter of 100 n.
m, the organic solvent content was 1% or less.

To 100 g of this aqueous polyurethane resin solution, 100 g of the same electrolytic copper powder as that used in Example 1 was mixed and dispersed to produce an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive coating material thus produced, the coating material was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial electroconductivity of the coating film of the water-based conductive paint of this example was 0.8 × 10 ⁻³ Ω · cm, which showed excellent conductivity performance similar to that of the conventional oil-based copper-based conductive paint. The formed coating film was left for 1000 hours in a 60 ° C., 95% RH humidity atmosphere, and as a result, the conductive performance was as small as 1.5 × 10 ⁻³ Ω · cm. In addition, the water-based conductive paint produced was kept at room temperature for 25
After being left at ℃, paint was applied on the phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.
10 ^- and ^{3 Ω} · cm, were almost same conductivity performance as the initial conductivity.

Example 5. In a 1000 ml four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 150 g of polytetramethylene ether glycol having a molecular weight of 1000, neopentyl glycol 36.4 g, dimethylolpropionic acid 33.5 g, N
-Methyl-2-pyrrolidone (42 g) and acetone (127 g) were charged, the internal temperature was adjusted to 30 ° C under a nitrogen stream, and 174.2 g of tolylene diisocyanate was dividedly added so that the internal temperature was 60 ° C or lower, and further 8 hours. After the reaction, NCO group content
3.7% urethane prepolymer was obtained. Next, 850 g of deionized water containing 25.2 g of triethylamine and 12.5 g of hydrazine monohydrate was maintained at 40 ° C, and 563.1 g of the above prepolymer was added dropwise to the mixture while stirring and mixing with a lab mixer. An aqueous polyurethane resin was obtained. This water-based resin solution is further subjected to reduced pressure deacetone at 50 ° C.,
Finally, an aqueous polyurethane resin solution having a non-volatile content of 36.3%, a pH of 8.0 and a viscosity of 330 cps / 25 ° C was obtained.

The polyurethane resin thus obtained has a glass transition point of 126 ° C. and an emulsion having an average particle diameter of 50 n.
m, organic solvent content was 3.9% or less.

To 100 g of this aqueous polyurethane resin solution, 100 g of the same electrolytic copper powder as that used in Example 1 was mixed and dispersed to prepare an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive coating material thus produced, the coating material was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial conductivity of the coating film of the water-based conductive coating material of this example was 1.0 × 10 ⁻³ Ω · cm, which showed excellent conductivity performance. The formed coating film was left for 1000 hours in a 60 ° C., 95% RH humidity atmosphere, and as a result, the conductive performance was as small as 1.5 × 10 ⁻³ Ω · cm. Furthermore, after leaving the produced water-based conductive paint for 1 month at room temperature of 25 ° C, the paint was applied on the phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film. As a result, 1.5 × 10 ⁻³ Ω ・cm, the deterioration of the conductive performance was small.

Example 6. 100 g of the aqueous polyurethane resin solution obtained in Example 1 was added with a specific surface area value of 2000 cm ² by the BET method.
/ G, 90% passed through a 44 μm sieve, electrolytic copper powder with an oxygen content of 0.10%
An aqueous conductive paint was manufactured by mixing and dispersing 100 g. In order to measure the initial conductivity of the water-based conductive coating material thus produced, the coating material was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial electroconductivity of the coating film of the water-based electroconductive coating material of this example was 1.3 × 10 ⁻³ Ω · cm, which was excellent electroconductivity. Also, the formed coating film was left for 1000 hours in a 60 ° C., 95% RH humidity atmosphere, resulting in 1.6 × 10 ⁻³ Ω · cm,
There was little deterioration in conductive performance. Furthermore, after leaving the produced water-based conductive paint for one month at room temperature of 25 ° C, the paint was applied on the phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film. As a result, 1.4 × 10 ^-3 Ω ・cm, which was almost the same as the initial conductivity.

Example 7. 100 g of the aqueous polyurethane resin solution obtained in Example 2 was added with a BET specific surface area value of 4000 cm ^2.
100 g of 100 g / g, 44 μm sieve was mixed and dispersed with 100 g of electrolytic copper powder having an oxygen content of 0.12% to produce an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive paint thus produced, the paint was spray-coated on a calcium silicate substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial conductivity of the coating film of the water-based conductive paint of this example was 0.7 × 10 ⁻³ Ω · cm, which was as excellent as the conventional oil-based copper-based conductive paint. Further, the formed coating film was left for 1000 hours in a 60 ° C., 95% RH humidity atmosphere, and as a result, it was 1.1 × 10 ⁻³ Ω · cm, and the deterioration of the conductive performance was small. Furthermore, the produced water-based conductive paint is kept at room temperature for 1 month.
After leaving it at 25 ° C, paint was sprayed onto the calcium silicate substrate and left standing at room temperature for 24 hours to form a 70 μm coating film. As a result, it was 0.8 × 10 ^-3 Ωcm, which was almost the same as the initial conductivity. It showed conductive performance.

Example 8. 100 g of the aqueous polyurethane resin solution obtained in Example 1 was added with a BET specific surface area value of 6000 cm ^2.
/ G, 100 μm through a 44 μm sieve, and 100 g of electrolytic copper powder with an oxygen content of 0.18% was mixed and dispersed to produce an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive paint thus produced, the paint was spray-coated on a calcium silicate substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial conductivity of the coating film of the water-based conductive paint of this example was 0.8 × 10 ⁻³ Ω · cm, which showed excellent conductivity performance similar to that of the conventional oil-based copper-based conductive paint. Further, the formed coating film was left in an atmosphere of 60 ° C. and 95% RH for 1000 hours, and the result was 1.3 × 10 ⁻³ Ω · cm, which showed little deterioration of the conductive performance. Furthermore, the produced water-based conductive paint is kept at room temperature for 1 month.
After leaving it at 25 ℃, spray paint on the calcium silicate substrate and leave it at room temperature for 24 hours to form a 70 μm coating film. As a result, it was 0.9 × 10 ^-3 Ωcm, which is almost the same as the initial conductivity. It showed conductive performance.

Example 9. 100 g of the aqueous polyurethane resin solution obtained in Example 1 was added with a BET specific surface area value of 5000 cm ^2.
100 g / g, 44 μm sieve, and 100 g of crushed powder of electrolytic copper powder having an oxygen content of 0.10% were mixed and dispersed to produce an aqueous conductive paint.
To measure the initial conductivity of the water-based conductive paint produced in this way, apply the paint on a phenolic substrate and
After standing for a time, a 50 μm coating film was formed.

The initial electroconductivity of the coating film of the water-based electroconductive coating material of this example was 1.1 × 10 ⁻³ Ω · cm, which showed excellent electroconductivity. The formed coating film was left in an atmosphere of 60 ° C. and 95% RH for 1000 hours. As a result, the conductivity was 1.6 × 10 ⁻³ Ω · cm, which was little deterioration. Furthermore, after leaving the produced water-based conductive paint at room temperature 25 ° C for one month, the paint was applied on the phenol substrate and left at room temperature for 24 hours to form a 50 μm coating film. As a result, 1.3 × 10 ^-3 Ω ・cm, the deterioration of the conductive performance was small.

Example 10. 100 g of the aqueous polyurethane resin solution obtained in Example 2 was added with a BET specific surface area value of 8000 cm.
100% of a ² / g, 44 μm sieve was passed through, and 100 g of crushed powder of electrolytic copper powder having an oxygen content of 0.20% was mixed and dispersed to produce an aqueous conductive paint. In order to measure the initial conductivity of the water-based conductive coating material thus produced, the coating material was applied onto a phenol substrate and left at room temperature for 24 hours to form a 50 μm coating film.

The initial electroconductivity of the coating film of the water-based electroconductive coating material of this example was 1.8 × 10 ⁻³ Ω · cm, which showed excellent electroconductivity. The formed coating film was left for 1000 hours in an atmosphere of 60 ° C. and 95% RH humidity. As a result, the conductivity was 2.3 × 10 ⁻³ Ω · cm, which showed little deterioration. Furthermore, after leaving the aqueous conductive paint prepared in 1 month at room temperature 25 ° C., the paint is applied on the phenol substrate, a result of forming a coating film of 50μm and left room temperature for 24 hours, 2.0 × 10 ^{- 3} Ω · cm, the deterioration of the conductive performance was small.

[0062]

[Comparative example]

Comparative Example 1. Aqueous polyurethane resin solution 10 obtained in Example 1
0 g, specific surface area value by BET method 1500 cm ² / g, 44 μm
To obtain a water-based coating composition by mixing and dispersing 100 g of a commercially available electrolytic copper powder having an oxygen content of 0.25%. To measure the initial conductivity of the water-based paint produced in this way, apply the paint on a phenol substrate and leave it at room temperature for 24 hours.
A μm coating was formed.

The initial conductivity of the coating film of the water-based paint of this comparative example was 5 × 10 ⁻³ Ω · cm, which was the same as that of the conductive paint using nickel powder. ℃,
As a result of being left for 1000 hours in a 95% RH humidity atmosphere, the conductivity was severely deteriorated to 10 ³ Ω · cm or more. Also, after leaving the water-based paint prepared in 1 month at room temperature 25 ° C., a result of measuring the conductivity in the same manner as the initial conductivity, 5.8 × 10 ^{- 3}
Although the storage stability of the paint was relatively good as Ω · cm, this water-based paint could not be used as a water-based conductive paint because of the poor moisture resistance of the paint film.

Comparative Example 2. In a 2000 ml four-necked flask equipped with a thermometer, a stirrer, and a nitrogen introduction tube, 500 g of polypropylene glycol having a molecular weight of 1000 and 1,4-butanediol 9.0
g, 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate 222.2 g were charged, the internal temperature was kept at 90 ° C. under a nitrogen stream, and the reaction was carried out for 6 hours.
A urethane prepolymer having a CO group content of 4.6% was obtained. Next, polyoxyethylene alkyl ether (molecular weight 200
0) A water-based polyurethane with a nonvolatile content of 40.0%, a pH of 6.5, and a viscosity of 150 cps / 25 ° C by gradually adding 1280 g of an aqueous solution containing 36.5 g of polyoxyethylene polyoxypropylene block polymer (molecular weight 8000) 36.5 g and emulsifying A resin solution was obtained.

The glass transition point of the polyurethane resin thus obtained was 3 ° C., and the average particle size of the emulsion was 3
It was 50 nm.

To 100 g of this aqueous polyurethane resin solution, 100 g of the same electrolytic copper powder as that used in Example 1 was mixed and dispersed to produce an aqueous paint. In order to measure the initial conductivity of the water-based paint thus produced, the paint was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial conductivity of the coating film of the water-based paint of this comparative example was 5 × 10 ⁻³ Ω · cm, which showed the same conductivity performance as that of the conductive paint using nickel powder. , 95
As a result of being left for 1000 hours in a% RH humidity atmosphere, the conductivity was severely deteriorated to 10 ⁶ Ω · cm or more. In addition, after the manufactured water-based paint was left at room temperature 25 ° C for one month, the conductivity was measured by the same method as the initial conductivity, and as a result, it was 10 ⁶ Ω · cm or more, and the storage stability of the paint was also very poor. It was

Comparative Example 3. In a 1000 ml four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube, 150 g of polycaprolafton diol having a molecular weight of 1000 and neopentyl glycol 3
6.4g, trimethylolpropane 4.5g, dimethylolpropionic acid 26.8g, N-methyl-2-pyrrolidone 188.5g,
222.2 g of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate was charged and the reaction was carried out for 8 hours while maintaining the internal temperature at 90 ° C. under a nitrogen stream and then using NCO.
A urethane prepolymer having a group content of 3.3% was obtained. next,
Deionized water containing 60.2 g of trimethylamine 20.2 g and ethylenediamine 15 g is kept at 40 ° C., 628.4 g of the above prepolymer is added dropwise while stirring with a lab mixer, and reacted to have a nonvolatile content of 35.2%, pH 8.0, and a viscosity. 280 cps
A water-based polyurethane resin solution of / 25 ° C was obtained.

The glass transition point of the polyurethane resin thus obtained was 95 ° C., the average particle size of the emulsion was 70 nm,
The organic solvent content was 13.9%.

To 100 g of this aqueous polyurethane resin solution, 100 g of the same electrolytic copper powder as that used in Example 1 was mixed and dispersed to produce an aqueous paint. In order to measure the initial conductivity of the water-based paint thus produced, the paint was applied on a phenol substrate and left at room temperature for 24 hours to form a 70 μm coating film.

The initial electroconductivity of the coating film of the water-based paint of this comparative example was 1.0 × 10 ⁻³ Ω · cm, which showed excellent electroconductivity. The formed coating film was left in an atmosphere of 60 ° C. and 95% RH for 1000 hours. As a result, the conductivity was 1.5 × 10 ⁻³ Ω · cm, which showed little deterioration in conductivity. However, the manufactured water-based paint
After being left at room temperature of 25 ° C for a month, the conductivity was measured by the same method as the initial conductivity, and the result was 10 ³ Ω · cm, which was not usable as a conductive paint.

[0072]

INDUSTRIAL APPLICABILITY In the present invention, by mixing and dispersing a specific copper powder in a specific aqueous polyurethane resin,
An excellent conductive coating film can be obtained by these synergistic effects, and it can be obtained a copper-based water-based coating material that can endure an environmental reliability test and also has significantly improved storage stability after being formed into a coating material and can be used practically. The water-based conductive paint according to the present invention has little deterioration in conductivity and is excellent in storage stability, so spray coating, brush coating,
An excellent conductive coating film can be easily obtained by a roll coater or a screen printing method. Further, since it is water-based, it can be diluted with water, the coating device can be easily washed, and there is no danger of environmental pollution or poisoning by an organic solvent or fire, and it is excellent in safety. Therefore, it can be used not only as a measure for electromagnetic shielding of electronic devices but also in a wide range of conductive paints and antistatic paints for building materials such as shielded rooms, and the industrial utility of the present invention is It can be said to be very large.

Claims (4)

[Claims] 1. A water-based polyurethane resin containing an organic polyisocyanate compound and a polyol compound having a carboxyl group as essential components has a specific surface area value by the BET method.
2000cm ² / g ~ 10000cm ² / g, 90% by weight on a 44μm sieve
A water-based conductive paint obtained by mixing and dispersing electrolytic copper powder having an oxygen content of 0.2% by weight or less, or copper powder obtained by crushing the electrolytic copper powder. 2. The water-based conductive coating composition according to claim 1, wherein the glass transition point (Tg) of the water-based polyurethane resin is 25 to 150 ° C. 3. The water-based conductive coating composition according to claim 1, wherein the emulsion average particle size of the water-based polyurethane resin is 20 nm to 200 nm. 4. The water-based conductive paint according to claim 1, wherein the organic solvent content of the water-based polyurethane resin is 5% or less.