JPH02151673A - Composition for conductive coating material - Google Patents

Abstract

PURPOSE:To obtain the title composition of improved conductivity and environmental pollution resistance by mixing two specified copper powders with a binder resin and an organometallic compound. CONSTITUTION:A mixed copper powder comprising 5-95wt.% low-density electrolytic copper of an apparent density of 0.3-2.0g/cm<3> and a tap density of 0.8-3.0g/cm<3> and 95-5wt.% high-density electrolytic copper powder of an apparent density of 0.8-3.0g/cm<3> and a tap density of 1.0-6.0g/cm<3> is coated with 0.05-10wt.%, based on the copper powder, organometallic compound having at least one easily hydrolyzable organic group and at least one difficultly hydrolyzable oleophilic group (e.g. isopropyltriisostearoyl zirconate). 40-90wt.% this copper powder and 5-60wt.%, based on the copper powder, binder resin (e.g. PS) are dispersed and dissolved in a solvent (e.g. toluene).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a composition for conductive paint, and more specifically,
The present invention relates to a conductive paint composition with improved conductivity and environmental resistance using copper powders having different apparent and tap densities.

Conventional Technology 1 Conventionally, conductive fillers such as nickel powder, silver powder, copper powder, and carbon powder are mixed with various binder resins as one of the electromagnetic shielding materials that protect electronic devices from electromagnetic interference. There's paint. This paint is applied to the surface of the plastic molded product using a spray brush or the like, and this coating shields electromagnetic waves. Among various conductive paints, copper-based conductive paints are cheaper than conductive paints using silver powder or nickel powder, and have excellent shielding effects.

However, copper powder itself and copper-based conductive paints have poor stability because the copper powder aggregates in the paint, making it difficult to obtain a good dispersion state, and moreover, they are easily oxidized in environments such as heat and humidity. However, there is a problem in that environmental resistance and conductivity are likely to deteriorate (attenuation of shielding effect). Various proposals have been made in the past to solve this problem. For example, surface treatment of copper powder with a coupling agent (JP-A-60-30200), coating of electrolytic copper powder with organic titanate (JP-A-59-174661),
A method for producing coated copper powder in which copper powder is coated with organoaluminium (Japanese Unexamined Patent Publication No. 59-179671), and treatment of copper powder with carboxylic acid (Japanese Unexamined Patent Publication No. 60-258273).
, Solder plating the surface of copper powder (JP-A-57-1)
13505), substitution precipitation of metallic silver on the surface of copper powder (JP-A-60-243277), and addition of unsaturated fatty acids and organic titanium compounds (JP-A-60-243277).
8-74759), addition of alkanolamine (JP-A-59-36170), and blending anthrazine (JP-A-56-163166).
etc. have been proposed.

Problems to be Solved by the Invention] However, although the conventional coated copper powder exhibits a certain degree of environmental resistance, it does not have conductivity and environmental resistance up to a practical level. In particular, electromagnetic shielding (EMI)
), there was a major problem in the deterioration of the initial shielding property and the shielding property after the environmental resistance test.

This invention was made based on the above background, and its purpose is to eliminate the drawbacks of the conventional conductive paint compositions and to significantly improve the conductivity and environmental resistance of conductive paints. An object of the present invention is to provide a composition for conductive paint.

[Means for Solving the Problems] The above problems are achieved by the conductive paint composition according to the present invention. That is, the conductive coating composition of the present invention is
A conductive composition comprising copper powder, a binder resin, a metal organic compound, and a solvent, the copper powder having an apparent density of 0. 3g
/ci ~2. Og/cm, tap density 0.8g/c
d~3. Og/ci low density electrolytic copper powder and apparent density 0.
8g/cIII~3. 0g1c! .

Tap density 1, Og/crj ~6. Og/
It is characterized by being made of mixed copper powder with high-density electrolytic copper powder of cr/r.

In a preferred embodiment of this invention, the metal organic compound is
The surface of the copper powder is coated with a proportion of 0.05 to 10% by weight based on the weight of the copper powder.

In another preferred embodiment of the present invention, the metal organic compound is blended into the composition in an amount of 0.05 to 10% by weight based on the solid weight of the composition.

This invention will be explained in more detail below.

Copper powder The copper powder used in this invention is a mixed copper powder of high-density copper powder and low-density copper powder.

Here, the low density copper powder has an apparent density of 0.1 g/d to 2.5 g
/d, preferably 0.3g/cril ~2. 0g/
ci! , tap density 0. 5 g/cm ~3. 5
g/cd.

Preferably 0.8g/crj ~3. It is an electrolytic copper powder of Og/r:i, and the copper powder obtained by the electrolytic method is washed,
It has been subjected to post-treatments such as neutralization and drying.

Here, the high-density copper powder has an apparent density of 0.5 g/cIII to 3
．． 5g/cIII, preferably 0.8g/cIII-3
．． 0g/ctL tap density 0. 8 g/d ~5.
0 g/crtl.

Preferably 1.0 g/ci to 6.0 g/ci. Og/c
yi electrolytic copper powder, for example, the post-treated low-density electrolytic copper powder described above is pulverized using a pulverizer such as an atomizer, Coroblex, or jet mill to adjust the apparent density and tap density. be able to.

The mixing ratio of low-density copper powder and high-density copper powder is 5 to 95% by weight.
, more preferably 10 to 90ffiffi%.

This is because if a conductive composition is prepared using mixed copper powder exceeding this limited range, its conductivity and environmental resistance will be significantly reduced.

Copper powder as a raw material that can be used in this invention is prepared in advance with H-organic compounds such as metals such as silver, nickel, zinc 1, and palladium, alloys such as solder, amines, amino acids, carboxylic acids and their derivatives, and metal organic compounds. It may be covered. Preferred coatings include metal organic compounds. The copper powder to be treated may also be pretreated to remove the oxidized coating from the surface of the copper powder using reagents such as inorganic acids, organic acids, various reducing agents, etc., or by reduction with hydrogen gas or ammonia gas. Can be removed. Further, the copper powder to be treated may be dried as a pretreatment.

Metal-organic compound The metal-organic compound coating used in a preferred embodiment of the present invention comprises a metal-organic compound represented by the following formula: [wherein M is zirconium or titanium and OR'
is an alkoxy group, OR2 and OR3 are acylate groups, R4 is an alkyl group or a hydrogen atom, and n is 1 or an integer exceeding 1.] A carboxylic acid ester represented by the following formula.

R-C-0'-R6 [In the formula, R5 is an alkyl group and oRB is an alkoxy group] A preferable composition ratio of the metal organic compound and the carboxylic acid ester is the sum of the metal organic compound and the carboxylic acid ester. Based on the amount, the carboxylic acid ester is 5 to 95% by weight.

Preferred metal organic compounds are those having at least one crystal hydrolyzable organic group and at least one hydrolyzable lipophilic group.

A metal organic compound preferred in terms of performance is obtained by reacting tetraalkoxyzirconium or tetraalkoxytitanium with several times the molar amount of a carboxylic acid, especially a higher fatty acid. For example, stearic acid in several times the mole, for example, 3 to 5 moles, per mole of tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetraisopropoxytitanium, or tetra-n-butoxyltitanium,
It is obtained by reacting higher saturated fatty acids such as valmitic acid, mystilic acid, lauric acid, and capric acid and their isomers, and higher unsaturated fatty acids such as oleic acid, linoleic acid, and liluic acid, and their isomers.

Such compounds include, for example, isopropyltriisostearoylzirconate, isopropyltridodecylbenzenesulfonylzirconate, isopropyltris(dioctylpyrophosphate)zirconate, tetraisopropylbis(dioctylphosphate)zirconate, tetraoctylbis(ditridecylphosphite). Zirconate, tetra(2,2-diallyloxymethyl-1-butyl)bis(di-tridecyl)phosphite zirconate, bis(dioctylpyrophosphate)oxyacetate zirconate, bis(dioctylpyrophosphate)ethylenezirconate, isopropyl trio Cutanoyl zirconate, Isopropyl dimethacryliisostearoyl zirconate, Isopropyl isostearoyl diacryl zirconate, Isopropyl tri(dioctyl phosphate) zirconate, Isopropyl tricumylphenyl zirconate, Isopropyl tri(N-aminoethyl-aminoethyl) zirconate, Dioctanoyl zirconate Mylphenyloxyacetate zirconate, diisostearoyl ethylene zirconate, isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl pyrophosphate) titanate, tetraoctyl bis (dioctyl pyrophosphate) titanate, Decyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl) bis(di-tridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyl Trioctanoyl titanate, isopropyl dimethacryliisostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, dicumylphenyloxyacetate titanates, diisostearoyl ethylene titanates, etc., and mixtures thereof.

Composition for Conductive Paint The composition for conductive paint according to the present invention is a composition containing a mixed/highly filled copper powder, a binder resin, and a solvent, and in a preferred embodiment, the metal organic compound is a copper powder in the composition. Surface coated or compounded.

A mixture of a flammable organic compound and a carboxylic acid ester at a mixing ratio of 5 to 95% by weight is coated with copper powder at a concentration of 0.05 to 10% by weight, or the solvent component is removed <0.05. ~
It may be blended into the composition at a content of 10% by weight.

Binder resins that can be used in this invention include:
It has good adhesion to plastics commonly used in electronic devices. For example, in contrast to electronic equipment plastics such as ABS, polystyrene, and polycarbonate, acrylic resins, polyurethane resins, polyester resins, styrene resins, phenolic resins,
Epoxy resin or the like can be used.

The content of the binder resin is 5 to 60% by weight, preferably 10 to 40% by weight based on the weight of the copper powder.

This is because if it is less than 10% by weight, it becomes gradually difficult to form a conductive composition, and if it is less than 5% by weight, this tendency becomes remarkable and it becomes completely impossible to form a composition. In addition, when the amount exceeds 40% by weight, the conductivity of the conductive composition gradually decreases, and the function as a conductive composition begins to deteriorate.
This is because this tendency becomes more pronounced when the number of fires exceeds the level of fire.

Solvents that can be used in this invention include toluene, thinner, hexane, benzene, methyl ethyl ketone, xylene, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, methyl isobutyl, which can dissolve additives such as binder resin. One or a mixture of two or more organic solvents such as ketones, ethyl acetate, butyl acetate, methyl cellosolve, and ethyl cellosolve are preferred. As these solvents, one type of single solvent or a mixture of two or more types of solvents are used in consideration of workability and the like.

The copper powder blended into this composition is 40 to 90% by weight, preferably 50% by weight, based on the solid content of the conductive composition.
~85% by weight.

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

[Function] In this invention having the above-described configuration, a highly filled copper powder obtained by mixing low-density and high-density copper powders with different apparent and tap densities is used, so that the coating film structure of the conductive composition can be made dense. and, accordingly, significantly improve the conductivity and environmental resistance of the coating film of the conductive composition. Furthermore, since the mixed copper powder has different average particle sizes, it is well dispersed in the binder resin and improves dispersibility.

The metal-organic compound used in a preferred embodiment of the present invention is centered around zirconium or titanium atoms, has a hydrophilic organic group that is easily hydrolyzed, and a lipophilic organic group that is difficult to be hydrolyzed, and has a hydrophilic organic group that is difficult to be hydrolyzed. Since it has a hydrophilic part and a hydrophobic part, the hydrophilic group (for example, an alkoxy group) causes a substitution reaction with the water adsorbed on the copper powder surface, and the organometallic compound molecules are placed on the copper powder surface with the hydrophilic part on the inside and the hydrophobic part on the outside. are arranged to form a rust-preventing film. Therefore, a rust preventive film is formed firmly and well on the surface of the copper powder, and high hydrophobicity is imparted to the surface of the copper powder. This anti-corrosion film is skillfully entangled with the binder resin molecules in the conductive composition by van der Waals forces, hydrogen bonds, ionic bonds, covalent bonds, etc. without impairing conductivity, and is formed during the stirring and kneading process. A good dispersion state of copper powder is formed by shear stress etc.

[Effect of the invention] As demonstrated from the following examples, claims 1.2 and 3
The composition for conductive paints significantly improves the conductivity and environmental resistance of conductive paints.

Furthermore, in detail, it has the ability to form a dense coating film, and the dispersibility of the copper powder in the composition has been improved, so it has improved conductivity, heat resistance, moisture resistance, It also improves electromagnetic shielding properties.

[Examples] The present invention will be specifically explained below based on Examples and Comparative Examples, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

experimental materials The materials used in the experimental examples are shown below.

Dendritic electrolytic copper powder A (Mitsui Mining Co., Ltd.) used in this example
Co., Ltd., MF-D2) are shown in Table 1.

Table 1 Characteristics of copper powder A 0.72 g/cri 1.30 g/cd 0.34 go/g 11.8 μm Apparent density Tap density Specific surface area Average particle size Dendritic electrolytic copper powder B used in this example ( Copper powder A
(pulverized with a hot mill) are shown in Table 2.

Table 2 Characteristics of copper powder B Apparent density 2.22g/c#! tap density
4.05g/cm Specific surface area 0.4
9d/g・1;, average particle size 3.4μm Dendritic electrolytic copper powders C and D used in this example (Copper powder C is a mixture of copper powders A and B in a ratio of 3:1, The copper powder (copper powder A and B mixed at a ratio of 5:1) is shown in Table 3.

Table 3 Characteristics of copper powders C and D Copper powder CD Apparent density (g/cm) 1. 08 0.87 Tap density Cg/ci) 1.75 1. 33 Specific surface area (go/g) 0.25 0.28 Average particle size (
μm) 7.7 9.3 The binder resins used in this example are shown in Table 4 below.

Table 4 Acrylic resin Acrybond BC-415B Mitsubishi Rayon Co., Ltd. Phenolic resin PL-2210 Gunei Chemical Industry Co., Ltd. The metal-organic compound crest agents used in this experiment are shown in Table 5 below. It was prepared from the metal alkoxide shown and higher fatty acid.

Table 3 Metal organic compounds No.

An organic zirconate compound containing 50% by weight of isopropyl isostearate obtained by reacting 3 times the mole of isostearic acid with 5-11 times the mole of tetraisopropoxytitanium. Isostearin obtained by reacting 3 times the mole of isostearic acid with 5-31 times the mole of tetra-n-butoxyzirconium. Organic zirconate compound containing 40% by weight of isobutyl oleate 5 - Organic zirconate compound containing 43% by weight of isobutyl oleate obtained by reacting 3 times the mole of oleic acid with 41 times the mole of tetraisobutoxyzirconium - Contains -0-butyl isostearate and n-butyl oleate 45% by weight 26% obtained by reacting 2 times the mole of isostearic acid and 1 times the mole of oleic acid with 51 times the mole of tetra-n-butoxyzirconium. Organic Zirconate Compound Comparative samples used in this example are shown in Table 6.

Table 6 No. Comparative sample 6-1 Isopropyl tridodecylbenzenesulfonyl titanate 6-2 Tetraisopropyl bis(dioctyl phosphite) titanate 6-3 Acetalkoxyaluminum diisopropylate 6-4 Anthrazine 6-57-Methacrylokidibrovir Trimethkinf/Experimental Example 1 Electrolytic conductivity of coating film The electrolytic copper powders A and B in Tables 1 and 2 and the highly filled copper powders C and D in Table 3 were combined with the metal H compound in Table '4X5. The comparison sample in Table 6 was added to copper powder by 0.05
．． 1.0.2.0.5.0.8.0% by weight was changed and coated.

A conductive paint was prepared using this surface-coated copper powder, the binder resin shown in Table 4, and the solvents toluene (for acrylic resin) and ethyl carpitol (for phenolic resin).

Conductor circuits were formed using the obtained conductive paint on an acrylic board and a phenol board, respectively, using a screen printing machine. 50℃/
The circuit was dried and cured for 30 minutes or at 150° C./30 minutes, and the volume resistivity of this circuit was measured.

As a result, the circuit obtained from the conductive paint containing the highly filled copper powder shown in Table 3 and the coated copper powder treated with the metal-organic compound shown in Table 5 had a resistance of 2x10-4 to 4x10 Ω・c.
I, small size 9X10-5 to 1XIO-4Ω・elm
It had a volume resistivity of .

On the other hand, the circuits obtained from the conductive paint containing copper powder treated with the comparison sample were between 8X10-' and 9x10 Ω"e
l, mostly I X 10-3~2X 10-”Ω・cl
It showed a volume resistivity of .

On the other hand, the letter circuit obtained from a conductive paint containing a single type of copper powder (coated copper powder treated with a metal-organic compound in Table 5)
The volume resistivity of 4×10−′ to 6×10−′Q·ca was shown.

This result shows that the conductive paint according to the present invention exhibits good conductivity.

Experimental Example 2 Electrolytic Conductivity of Coating Film Comparison of electrolytic copper powders A and B in Tables 1 and 2 above, highly filled copper powders C and D in Table 3, metal-organic compounds in Table 5, and Table 6 sample to copper powder, 0.05.1
゜Added at 0.2.0.5.0.8.0% by weight,
A conductive paint was prepared using the binder resin in Table 4 and the solvents toluene (for acrylic resin) and ethylcarpitol (for phenolic resin).

Conductor circuits were formed using the obtained conductive paint on an acrylic board and a phenol board, respectively, using a screen printing machine. 50℃/
The volume resistivity of this circuit was measured after dry explosion and curing for 30 minutes or at 150° C./30 minutes.

As a result, the circuit obtained from the conductive paint to which the highly filled copper powder shown in Table 3 and the metal-organic compound shown in Table 5 was added was 2X10'~4X10-'Ω'e111, not less than 9X10~ It had a volume resistivity of 1×10 −4 Ω·cIll.

On the other hand, the circuits obtained from the conductive paint to which the comparison sample was added were 8X10 to 9X10' ohm elm, mostly I
It exhibited a volume resistivity of X 10-3 to 2X 10-''Ω·cll.

On the other hand, circuits obtained from conductive paints containing a single type of copper powder (added with metal-organic compounds from Table 5)
It exhibited a volume resistivity of ~6xlO'Ω''cm.

This result shows that the conductive paint according to the present invention exhibits good conductivity.

Experimental Example 3 Heat and Humidity Resistance of Paint Films The conductor circuit boards prepared in Experimental Examples 1 and 2 were left at a temperature of 85°C and a humidity environment of 60°C/95% RH for 2000 hours, and the rate of change in resistance of the paint film was measured. did.

As a result, in a high-temperature environment of 85°C, the coating film obtained from the conductive paint containing the highly filled copper powder and metal-organic compound shown in Table 3 was mostly less than 596, and at most 7 %
It was about. In a humidity environment of 60° C./95% RH, the temperature was less than 2% in most cases, and about 4% at most.

On the other hand, the coating film obtained from the conductive paint containing the comparative sample or using a single type of copper powder is as low as 20% and as high as 150-200% in a high temperature environment of 85°C.
Met. In a humidity environment of 60°C/9596RH, it was at least 15% and at most 80-130%.

From the above results, it is clear that the conductive paint of the present invention has excellent heat resistance, humidity resistance, and aging resistance at high temperatures and high humidity.

Experimental Example 4 Electromagnetic Shielding Properties The conductive compositions prepared in Experimental Examples 1 and 2 were applied to the entire surface of a 15×15c+s acrylic board and a phenol board by spray coating and screen printing, and then heated at 50°C/
It was dried and cured at 150° C. for 30 minutes and 730 minutes, and the electromagnetic shielding effect was measured using the Atopane test method.

As a result, the electrical conductivity containing highly filled copper powder and metal-organic compounds shown in Table 3! 2! The coated plate obtained from the material had a near-field electric field (500 MHz) of 55 to 60 dB, not less than 60 dB. In addition, the magnetic field of the near field (500
MHz), it was 55 to 60 dB, not less than 60 dB.

On the other hand, coated plates obtained from conductive paints that include comparison samples or that use a single type of copper powder are mostly 40 to 45 dB, often less than 35 dB, in the near-field electric field (500 MHz). Met. In addition, the magnetic field of the near field (
500MHz), 40-45dB, no less than 25d
It was below B.

From the above results, it can be seen that the conductive paint of the present invention has excellent electromagnetic shielding properties.

Experimental example 5 Film thickness The film thickness of the fully coated plate of Experimental Example 4 was measured.

As a result, the film thickness of the coated plate according to the present invention was generally 30 to 40 μm and at most 50 μm thick.

On the other hand, coated plates obtained from conductive paints containing comparative samples and those using a single type of copper powder were mostly 60 to 70 μm in thickness and at least about 50 μm in thickness.

From the above results, it can be seen that the conductive composition according to the present invention exhibits excellent electromagnetic shielding properties despite being a thin film.

Claims (1)

[Claims] 1. A conductive composition containing copper powder, a binder resin, a metal organic compound, and a solvent, wherein the copper powder has an apparent density of 0.3 g.
/cm^3~2.0g/cm^3, tap density 0.8g
/cm^3~3.0g/cm^3 low density electrolytic copper powder,
Consists of mixed copper powder with high-density electrolytic copper powder having an apparent density of 0.8 g/cm^3 to 3.0 g/cm^3 and a tap density of 1.0 g/cm^3 to 6.0 g/cm^3. A conductive paint composition characterized by: 2. The metal organic compound is 0.05 to 0.05 based on the weight of copper powder.
2. The conductive coating composition according to claim 1, wherein the conductive coating composition is coated on the surface of the copper powder in a proportion of 10% by weight. 3. The metal organic compound is based on the solid weight of the composition,
The conductive coating composition according to claim 1, wherein the conductive coating composition is blended in the composition in a proportion of 0.05 to 10% by weight.