JPH04100868A - Conductive paste material - Google Patents

Abstract

PURPOSE:To provide a paste material which gives a high electroconductivity when the paste is applied and dried but shows insulating properties after it has been heat-treated by mixing a conductive material of a specific organic electrolyte, an organic binder and a solvent as the essential components. CONSTITUTION:In a conductive paste material comprising a conductive material, an organic binder and a solvent as the essential components, organic electrolytes selected from sulfonates, sulfates, organic phosphates and organic carboxylates are used as the conductive material. The salts of the organic electrolytes may preferably include amine salts, ammonium salts, quaternary ammonium salts and alkali metal salts. The conductive paste material is applied, dried and then heat-treated so that its film is insulated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a conductive paste material and a method for insulating a coating film, and more specifically, the volume resistivity thereof is
The present invention relates to an electrically conductive paste material that has a low electrical conductivity when the paste is applied and dries, but becomes electrically conductive after heat treatment, and a method for insulating a coating film using this paste material.

[Prior art and problems to be solved by the invention] Generally, conductive paste materials are made of an organic binder (hereinafter referred to as binder) such as epoxy resin, polyester resin, acrylic resin, or phenol resin, a conductive substance, and a solvent. Basically configured.

These conductive paste materials have conventionally been used as conductors for circuit boards, and recently as electromagnetic shielding materials for printed circuit boards. For these purposes, it is essential to exhibit high electrical conductivity after paste hardening treatment, and various studies have been carried out.

On the other hand, in the field of electronic material development, there has been an increasing demand for conductive pastes that have new characteristics not found in the past.

For example, as circuit patterns become denser, incorrect wiring often occurs when connecting terminals at the design stage. One possible solution to this problem is to use a material that can be easily checked for continuity during temporary wiring and that can be easily operated as an insulator during actual wiring.

Also, spacers are used to maintain gap uniformity between two panels of a liquid crystal display panel. During the LCD panel assembly process, static electricity is generated when the protective film of the polarizing plate attached to the LCD panel is peeled off, but since the spacer is almost an electrical insulator, the electric charge generated at this time is transferred to the metal. When a discharge occurs through a conductive object such as a human hand, spacers located in the discharge path within the liquid crystal display panel remain charged. As a result, when a driving voltage is applied to the liquid crystal display panel, the electric field around the spacer changes,
There was a problem with uneven lighting.

In this case, if you temporarily wire the liquid crystal drive electrode wires to release static electricity during assembly, and use a conductive paste material that acts as an insulator for the main wiring that connects the drive LSI, this problem can be solved. can be solved.

However, a conductive paste material suitable for the above purpose has not yet been developed.

(Means for Solving the Problem) The present inventors have discovered the above-mentioned features that were not found in the past, that is, the paste exhibits high conductivity when applied and dried, and exhibits insulation after heat treatment. As a result of extensive research in order to obtain a paste material with characteristics, the present invention has been completed.

That is, the present invention provides a conductive paste material containing a conductive substance, an organic binder, and a solvent as essential components, wherein the conductive substance is a sulfonate, a sulfate ester salt, an organic phosphate,
A conductive paste material characterized by being an organic electrolyte selected from organic carboxylates, and a method for insulating a coating film characterized by applying this conductive paste material, drying, and then subjecting it to heat treatment. When the conductive paste is applied to a predetermined area, dried, and then heat-treated for the purpose of curing the binder, etc., these organic electrolytes dissociate due to heat and lose their conductivity. It is something to be used.

The organic electrolyte used in the present invention is selected from sulfonates, sulfate ester salts, organic phosphates, and organic carboxylates, and the types of salts include amine salts, ammonium salts, quaternary ammonium salts, Or sodium,
Alkali metal salts such as potassium are preferably used.

Examples of the sulfonic acid salts used in the present invention include salts of dinonylnaphthalene disulfonic acid, dinonylnaphthalene monosulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, polystyrenesulfonic acid, and the like. Examples of industrially produced sulfonates include NACURE manufactured by Kusumoto Kasei.
1323, NACURE2530. NACUREX4
9-110. NACUl? E3525, NACURE
2500X, NACURE5225 (all product names), among others, NACURE2500
X (para-toluenesulfonic acid amine salt) at 60°C
Since it dissociates in the vicinity, it can be particularly preferably used as a conductive substance in a low-temperature curing conductive paste.

Examples of the sulfuric acid ester salt used in the present invention include salts such as dodecyl sulfuric acid and hexyl sulfuric acid.

Examples of the organic phosphate used in the present invention include salts of phosphoric acid, monododecyl phosphoric acid, didodecyl phosphoric acid, and the like. Industrially produced organic phosphates include:
An example is NACURE4167 (trade name) manufactured by Kusumoto Kasei ■.

The organic carboxylic acid salts used in the present invention include acetic acid,
Examples include salts of maleic acid, polyacrylic acid, polymethacrylic acid, and the like.

These organic electrolytes can be used alone or in combination of two or more.

Next, as the binder used in the present invention, commonly used binder resins for paints can be used. For example, thermoplastic resins such as acrylic, vinyl, cellulose, and vinyl chloride/vinyl acetate copolymers, phenolic resins, urea resins, amino resins, alkyd resins, silicone resins, furan resins, and polyester resins. Thermosetting resins such as epoxy resins, polyurethane resins, etc. can be used. In particular, as the thermosetting resin, phenolic resins, amino resins, and epoxy resins are preferred.

Examples of phenolic resins include phenol, cresol,
Xylenol, p-alkylphenol, chlorophenol, bisphenol A.

Examples include resins obtained by adding and condensing aldehydes such as formalin and furfural to those having phenolic hydroxyl groups such as phenolsulfonic acid and resorcinol. Particularly preferred are resol type phenolic resins. When using a novolac type phenolic resin, it is preferable to use hexamethylene diamine together.

Examples of the amino resin include resins in which formalin is added and condensed to amino groups such as urea, melamine, guanamine, aniline, and sulfonamide, and preferably melamine resins in which formalin is added and condensed with an alkyl ether. As the alkyl etherified melamine resin, for example, methyl melamine resin such as Super Heccamin L-105-60 manufactured by Dainippon Ink & Chemicals, Super Heccamin J-820-60
゜J-840, L-117-60, L-127-60,
n-butylated melamine resin such as L-109=50, Super Hetsukamine G-821-60, L-118-60, L
-121-60, TO-139-60, Lllo-60
, L-125-60, 47-508-50, L-145
- Isobutylated melamine resin such as 60L116-70 (
Both are product names).

When curing melamine resin, no catalyst is required when curing at a high temperature of 200°C or higher, but at normal curing temperatures, p-1-
Organic acids such as luenesulfonic acid, naphthalenesulfonic acid, and linoleic acid; catalysts such as inorganic acids such as sulfuric acid and hydrochloric acid; or latent catalysts such as long-chain amine salts of p-toluenesulfonic acid may be mixed in advance. preferable.

As the epoxy resin, bisphenol diepoxides are preferred, such as Epicoat 827 manufactured by Shell Chemical Co., Ltd.
．． 828.834.1001.1002.1004゜1
007, 1009, Araldite G manufactured by Ciba Geigy
Y-250, 260, 280, 60716084609
7,6099, and Epiclon 8IO51000, 1010, and 3010 (all trade names) manufactured by Dainippon Ink and Chemicals.

Furthermore, novolak epoxy resins having an average of three or more epoxy groups can also be used.

As the novolank epoxy resin, one having a molecular weight of 500 or more is suitable. Examples of such novolank epoxy resins that are industrially produced include the following. Ciba Geigy Araldite EPN
1138.1139. ECN1237゜1280, 1
299, DEN431.438 manufactured by Dow Chemical Company, Epicoat 152.154 manufactured by Shell Chemical Company, EPR-0100, ERRB-0447, ER manufactured by Union Carbide Company
There are LB-0488, EOCN series manufactured by Nippon Kayaku ■, etc.

Furthermore, a curing catalyst and a diluent for the epoxy resin can be further used if necessary. Curing catalysts for epoxy resins include aliphatic amines such as diethylenetriamine, triethylenetetramine, and tetraethylenepencumine, aromatic amines such as benzyldimethylamine, diaminodiphenylmethane, and diaminodiphenylsulfone, maleic anhydride, phthalic anhydride, and hexahydrochloride. Phthalic anhydride, methylnadic anhydride, p-dimethylaminohenzaldehyde, boron trifluoride/piperidine complex, etc. can be used. As a diluent for epoxy resin, n-
Reactive diluents such as methyl glycidyl ether, octylene oxide, phenyl glycidyl ether, styrene oxide, allyl glycidyl ether, glycidyl methacrylate, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, cellulose triacetate, xylene, castor oil, pine oil, etc. Non-reactive diluents such as alkyl(nonyl)phenols, polyglycols, polysulfides, diallyl phthalates, semi-reactive diluents such as ε-caprolactam, butyrolactone can be used.

The above-mentioned thermoplastic resins and thermosetting resins used in the present invention may be used alone or in combination of two or more. Furthermore, the mixing ratio of the binder in the present invention is a conductive material!
5 to 85 parts by weight per 10 parts by weight, preferably 10 to 85 parts by weight
If the amount is less than 5 parts by weight, the absolute amount of the binder is insufficient, resulting in poor fluidity of the resulting composition and poor printability. Conversely, if the amount of the binder exceeds 85 parts by weight, the absolute amount of the conductive substance will be insufficient, and the required conductivity will not be obtained.

To manufacture the conductive paste material of the present invention, for example,
Dissolve the binder in a solvent, then add a conductive substance,
This is sufficiently uniformly kneaded using a disper, ball mill, or three-roll mill.

Solvents that can be used here include benzene, toluene, hexanone, dioxane, solvent naphtha,
Industrial gasoline, cellosolve acetate, cellosolve ethyl,
Butyl cellosolve, butyl cellosolve acetate, butyl carpitol acetate, dimethylformamide, dimethyl acetamide, N-methylpyrrolidone; Alcohol solvents such as isopropatool, butanol, butyl carpitol; Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ethyl acetate, amyl acetate,
Known solvents such as acetate ester solvents such as butyl acetate may be used. The amount of solvent blended varies depending on the type of crosstalk machine, crosswire conditions, and type of solvent. It is preferable to adjust the amount of solvent so that the viscosity of the paste after kneading is within a range that allows screen printing.

The volume resistivity of the thus obtained paste before heat treatment is usually about I Xl0-' - I Xl06 Ωcm, but a desired volume resistivity can be obtained by selecting the preparation conditions.

The conductive paste of the present invention usually has a 40 to 200
By performing heat treatment at a temperature of .degree. C. for about 20 minutes to 1 hour, the material easily loses its conductivity and becomes an insulator. Choosing a formulation that becomes an insulator at room temperature below 40°C is undesirable because the storage stability (pot life) at room temperature will be shortened. Further, if a temperature higher than 200°C is required for heat treatment, it is not preferable when used in the field of electronic materials, since there may be problems with the heat resistance of peripheral equipment. Further, the volume resistivity value after heat treatment is preferably lXl0'ΩC- or more, more preferably I
Xl0I0Ωca or more.

Incidentally, the volume resistivity value of the conductive paste before and after the heat treatment was measured by the following method.

That is, screen printing was performed on a glass-epoxy substrate, and the volume resistivity values before and after heat treatment were measured using a two-terminal method under a DC voltage of 20 V (26°C/60% R, H, atmosphere, measuring device). (■ R8340A digital ultra-high resistance meter manufactured by Atohanchist).

Note that the volume resistivity value was calculated using the following formula.

Volume resistivity value (0cm) - RxtxW/However, R
: resistance value between electrodes (Ω), t: thickness of coating film (0 layer), W
: Width of coating film (c+w), L : Path between electrodes! (0 layer).

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples. In the examples, parts indicate parts by weight.

Example 1 Polyvinylphenol (
50%) (Tylcarbitolne 8 liquid) 2.01, isobutylated melamine (60%) as a thermosetting resin binder
butanol solution) 1.0 part, NACU as a conductive substance
Weighed out 1.25 parts of RE2500X (manufactured by Kusumoto Kasei Co., Ltd., para-toluenesulfonic acid amine salt) and 1.0 part of methyl ethyl ketone (MEK) as a solvent, and mixed it with 3 rolls for 30 minutes.
A conductive paste was obtained by kneading.

Using this conductive paste, a pattern with a width of 2IIe and a total length of 10CI was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesh Tetron screen. The volume resistivity value of the obtained conductive pattern was 1.
It was 9 x 10' Ω CIm.

Next, the paste was cured by heating at 70° C. for 20 minutes to obtain a cured paste film with a thickness of 20°. The volume resistivity value of the obtained coating film is 2
．． It was 5×10”Ω1.

Example 2 Polyvinylphenol (
50% butyl calpitol solution) 2.0 parts, isobutylated melamine (60% butanol solution) 1.0 part as thermosetting resin binder, NACURE as conductive material
0.5 parts of 2500X (manufactured by Kusumoto Kasei, para-toluene sulfonic acid amine salt), 1 part of methyl ethyl ketone as a solvent
．． 0 part was weighed out and kneaded for 30 minutes using three rolls to obtain a conductive paste.

Using this conductive paste, a pattern with a width of 2 mm and a total length of 10 cm was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesh Tetron screen. The volume resistivity value of the obtained conductive pattern was 8.9
Xl, 0'ΩC111.

Next, the paste was cured by heating at 40°C for 60 minutes to obtain a cured paste film with a thickness of 18 mm. The volume resistivity value of the obtained coating film was 7
．． It was 9×10”Ω1.

Example 3 Polyvinylphenol (
50% butyl calpitol solution 1) 2.0 parts, thermosetting resin binder: isobutylated melamine (60% butanol solution): 1.0 parts, conductive material: 7 NACUR
EX49-110 (manufactured by Kusumoto Kasei ■, dinonylnaphthalenedisulfonic acid amine salt) 0.5 m, 1.0 part of methyl ethyl ketone as a solvent was weighed out, and mixed with 3 rolls.
A conductive paste was obtained by kneading for 0 minutes.

Using this conductive paste, a pattern with a width of 2 mm and a total length of 10 cm was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesh Tetron screen. The volume resistivity value of the obtained conductive pattern was 4.6
X 10'Ωcm.

Next, the paste was cured by heating at 90° C. for 40 minutes to obtain a cured paste film with a thickness of 25 μm. The volume resistivity value of the obtained coating film was 8
．． It was 5×10”Ω1.

Example 4 Polyvinylphenol (
50% butyl calpitol solution) 2.0 parts, thermosetting resin binder: isobutylated melamine (60% butanol solution): 1.0 part, linoleic acid: 0.43 parts, conductive material: NACURE 3525 (manufactured by Kusumoto Kasei Corporation, 0.5 part of dinonylnaphthalenedisulfonic acid amine salt) and 1.0 part of methyl ethyl ketone as a solvent were weighed out and kneaded for 30 minutes using three rolls to obtain a conductive paste.

Using this conductive paste, a pattern with a width of 2 mm and a total length of 10 CI11 was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesotron screen. The volume resistivity value of the obtained conductive pattern was 5
．． It was 7×10′ΩCl11.

Next, the paste was cured by heating at 110° C. for 30 minutes to obtain a cured paste film with a thickness of 19 mm. The volume resistivity of the resulting coating film was 4.9×10”Ω1.

Example 5 2.0 parts of polyvinylphenol (50% butylcarpitol solution) as binder, 1.0 part of acrylic resin (60 parts solution), 1.5 parts of sodium polystyrene sulfonate (molecular weight 50,000) as conductive material 1 part and 1.0 part of ethanol as a solvent were weighed out and kneaded for 30 minutes using three rolls to obtain a conductive paste.

Using this conductive paste, a divalent pattern with a total length of 10 cm+ was printed on a glass epoxy resin substrate using a screen printing machine with a 180-menshitetron screen. The volume resistivity value of the obtained conductive pattern was 2.
7 XIO3Ωα.

Next, the paste was cured by heating at 200° C. for 30 minutes to obtain a cured paste film with a thickness of 15 m+. The volume resistivity of the resulting coating film was 9.4 x 10''Ω1.

Example 6 As a binder, 2.0 parts of polyvinylphenol (50% butylcarpitol solution 1), acrylic resin (60% M
EK solution) 1.0 parts, 2.5 parts of dodecylhenzenesulfonic acid trimethylamine salt as a conductive substance, and 1.0 parts of methyl ethyl ketone as a solvent were weighed out and kneaded for 30 minutes using three rolls to form a conductive paste. Obtained.

Using this conductive paste, a pattern with a width of 2III11 and a total length of 10 cn+ was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesh Tetron screen. The volume resistivity value of the obtained conductive pattern was 1.7 XIO'Ωcn+.

Next, the paste was cured by heating at 190°C for 30 minutes to obtain a cured paste film having a thickness of 21 mm. The volume resistivity value of the resulting coating film was 4.4×10 12 Ωcm.

Example 7 As a binder, 2.0 parts of polyvinylphenol (50% butylcarpitol solution), acrylic resin (60% 1
Weigh out 1.0 parts of solution), 1.5 parts of monododecyl phosphate triethanolamine salt as a conductive substance, and 1.0 parts of methyl ethyl ketone as a solvent, and knead with three rolls for 30 minutes to make a conductive paste. I got it.

Using this conductive paste, a pattern with a width of 2 am and a total length of 10 cm was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesotron screen. The volume resistivity value of the obtained conductive pattern was 9.4
It was XIO'Ω1.

Next, the paste was cured by heating at 160° C. for 45 minutes to obtain a cured paste film with a thickness of 16 mm. The volume resistivity value of the resulting coating film was 1.5×10'4 Ωcm.

Example 8 2.0 parts of polyvinylphenol (50% butylcarpitol solution) and acrylic resin (60% M
EK solution) 1.0 part, linoleic acid 0.43 part, sodium polyacrylate (molecular weight 150,000) as a conductive substance 1
．． 5 parts and 1.0 part of methanol as a solvent were weighed out and kneaded using three rolls for 30 minutes to obtain a conductive paste.

Using this conductive paste, a pattern with a diameter of 2III11 and a total length of 10- was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesh Tetron screen. The volume resistivity value of the obtained conductive pattern was 8.4 XIO'ΩC11I.

Next, the paste was cured by heating at 190° C. for 60 minutes to obtain a cured paste film with a thickness of 22 mm. The volume resistivity value of the resulting coating film was 4.9XIO''Ω1.

Example 9 2.0 parts of polyvinylphenol (50% butylcarpitol solution) as a binder, 1.0 part of acrylic resin (60 parts solution), 0.43 part of linoleic acid, triethanolamine dodecyl sulfate as a conductive substance 1.5 parts of salt,
0.5 part of isopropanol was weighed out as a solvent and kneaded for 30 minutes using three rolls to obtain a conductive paste.

Using this conductive paste, a pattern with a width of 2 mm and a total length of 10 cm was printed on a glass epoxy resin substrate using a screen printing machine with a 180 mesh Tetron screen. The volume resistivity value of the obtained conductive pattern was 4.4
It was XIO'Ωcm.

Next, it was heated and cured at 190°C for 60 minutes to a thickness of 241tI.
A paste cured film of n was obtained. The volume resistivity value of the resulting coating film was 5.8×10''ΩΩ.

〔Effect of the invention〕

The conductive paste obtained in the present invention has a characteristic that the volume resistivity increases and becomes insulating through heat treatment. Furthermore, by selecting an organic electrolyte and a binder, it is possible to obtain a cured film that easily loses conductivity even at around 60°C, so it can be widely used in various electronic materials such as electronic circuits with low heat resistance.

Claims (3)

[Claims] 1. In a conductive paste material containing a conductive substance, an organic binder, and a solvent as essential components, the conductive substance is an organic electrolyte selected from sulfonates, sulfate ester salts, organic phosphates, and organic carboxylates. Characteristic conductive paste material. 2. The conductive paste material according to claim 1, wherein the organic electrolyte is an amine salt, ammonium salt, quaternary ammonium salt or alkali metal salt. 3. Coating the conductive paste material according to claim 1 or 2,
A method for insulating a coating film, which is characterized by subjecting it to heat treatment after drying.