JPS60118746A - Conductive composition containing copper - Google Patents

Abstract

PURPOSE:To obtain a composition of high storage stability and electrical conductivity, developing no rust on the surface of cured products, by incorporating a formulation containing copper powder as conductive material with tall oil, rosin, rosin ester, and/or higher fatty acid amide. CONSTITUTION:The objective composition can be obtained by incorporating a formulation made up of (A) 50-98 (pref. 70-93) wt%, based on the final composition, of copper powder (e.g. reduced one, electrolytically deposited one, with a size <=300mum pref. 1-100mum) and (B) resin binder (curing matter having function as binder; e.g. styrene resin) with, as additive(s) (C) 0.001-0.3 (pref. 0.005-0.1) pt.wt. per pt.wt. of the copper powder, of at least one sort of compound selected from tall oil, rosins (e.g. gum rosin, tall rosin), rosin esters (e.g. methyl esterified rosin) and higher fatty acid amides (pref. of 1-24C; e.g. lauric acid amide).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a conductive composition, particularly a conductive composition that exhibits excellent performance in electrical conductivity, etc. by coexisting a specific organic compound in a compound system containing metallic copper powder as a conductive material. It is about things.

Conventionally, paints and adhesives containing silver as a conductive material have been widely used as various electronic components, electrodes of printed wiring boards, wiring materials, or bonding materials. Silver is used as the main conductive material because it has the highest electrical conductivity among metals and has higher chemical stability than base metals such as copper. However, the material cost is very high, there are many restrictions on product design due to the silver migration phenomenon, and there are major drawbacks such as reliability problems depending on the usage conditions.

Therefore, a replacement with a copper conductive composition based on cheaper copper powder is desired.

However, a significant drawback in this case is that, due to the high oxidizability of the copper powder dispersed in the binder, during storage as a composition,
During the formation of a coating film or the like during its use, the surface of the copper powder is oxidized and the contact resistance between powder particles increases, resulting in insufficient conductivity and difficulty in maintaining conductivity.

For this reason, many attempts have been made to add various additives to copper-containing compositions to impart good electrical conductivity and to maintain that electrical conductivity as much as possible.

For example, phosphorous acid or its derivatives (Japanese Patent Publication No. 52-2493
6), anthracene or its derivatives (Japanese Patent Application Laid-open No. 1983)
-103'260), hydroquinone derivatives (JP-A-57-55974), etc. have been proposed.

However, according to research conducted by the present inventors, copper-containing conductive compositions containing these additives have problems in terms of storage stability due to the so-called skinning phenomenon that hardens the surface and impairs quality. For some, the specific resistance value when cured into a form such as a coating film is at most about 10"3 Ωcm, which is still not sufficient compared to the level of silver-containing conductive compositions. When stored under humidity for a long time, a verdigris-like substance is formed on the surface of the cured product, resulting in a significant decrease in electrical conductivity.Therefore, there have been few additives that are sufficiently satisfactory for practical use.

The present invention was made in order to eliminate the drawbacks of the above-mentioned conventional technique 1, and its objectives are to provide a composition with good storage stability, excellent conductivity, and to prevent rusting on the surface of the cured product. An object of the present invention is to provide a copper-containing conductive composition that does not cause poor appearance.

The present inventors have found that it is extremely effective for the above-mentioned problem to add the specific organic compound described in detail below as an additive to a compound system mainly composed of copper powder and a resin binder. Heading Completing the Invention.

That is, the present invention is characterized in that it contains at least copper powder, a resin binder, and one or more compounds selected from the group of tall oil, rosin, rosin ester, and amides of higher fatty acids as additives. The present invention relates to a conductive composition.

Examples of the copper powder used in the composition of the present invention include reduced copper powder obtained by reducing oxidized steel, electrolytically deposited copper powder, and copper powder obtained by pulverizing metallic copper. The shape is not particularly limited, and various shapes such as flake, resin, and spherical shapes can be used. In addition, these various copper powders are
A mixture of more than one species can also be used. The particle size of these copper powders is selected depending on the intended use of the composition, but is generally 300 μm or less, preferably 1 to 100 μm.

The resin binder in the present invention is a general term for curable substances that have a binder function to keep the composition in a desired shape, and is a polymeric substance that has already become a polymeric substance before it is finally cured. It also includes substances that can be turned into polymeric substances through a curing reaction. Specifically, vinyl polymerizable resins such as styrene resins, acrylate resins, methacrylate resins, diallyl phthalate resins, and unsaturated polyester resins, carbonate resins, polyarylsulfone resins, and alkyl 7
Examples include carbon resin, phenol resin, xylene resin, various amino resins, urethane resin, cellulose resin, epoxy resin, polyimide resin, and silicone resin.

These resins may be used in any form such as a solvent type dissolved in an organic solvent, an aqueous type such as an emulsion, or a completely liquid resin type.

The composition of the present invention is characterized in that it contains an additive selected from the group of tall oil, rosin, rosin ester, and amides of higher fatty acids as the third essential component.

To explain these compounds in more detail, tall oil is recovered as a by-product during the manufacture of valves from graph 1 of fodder wood, and is composed of resin acids mainly consisting of abietic acid and its isomers, oleic acid, and linoleic acid. Contains fatty acids, etc.

Tall oil is a dark brown oily substance whose composition is generally 25 resin acids.
-55% by weight and fatty acids in the range of 30-60% by weight, but any composition can be used for the purpose of the present invention.

Rosin includes gum rosin obtained by distilling turpentine oil from fresh pine resin collected by directly cutting pine trees, wood rosin obtained by cutting pine roots into chips and extracting the rosin with a solvent, and furthermore obtained by precision fractionation of crude tall oil. There are toll rosins that can be used as a main component (80 to 97% by weight), all of which contain C mixtures consisting of abietic acid and its isomers.

Any of these various rosins having different compositions can be suitably used in the composition of the present invention. Furthermore, in order to eliminate conjugate double viscosity of resin acids that are active against radical species, heat treatment at high temperatures using noble metal catalysts, hydrogenated disproportionated rosin, hydrogenated rosin, or heating in the presence of acidic catalysts is performed. Polymerized rosin etc. obtained by the treatment can also be used in the same manner.

Furthermore, various rosin esters can be used as additives in the composition of the present invention. Rosin ester (esterified rosin)
Abietic acid, which is the main component of varosin, and its isomers are reacted with 1 (il) or polyhydric alcohols at high temperatures, such as methyl esterified rosin, monoethylene glycol esterified rosin, diethylene glycol esterified rosin. Examples include rosin, glycerin-esterified rosin, and pentaerythritol-esterified rosin.

In addition to the above-mentioned rosins and rosin silos, various modified rosins prepared by adding maleic anhydride, fumaric acid, acrylic acid, cyclopentadiene, etc. to the rosin by Diel-Alder reaction, or further reacting with alcohol can also be suitably used.

Furthermore, as additives that can be used in the composition of the present invention, there are amides of higher fatty acids. In particular, amides derived from higher fatty acids having 10 to 24 carbon atoms exhibit excellent effects. Specifically, lauric acid amide, myristic acid amide,
Examples include palmitic acid amide, stearic acid amide, oleic acid amide, linoleic acid amide, and brassic acid amide.

It goes without saying that each of the various additives detailed above is effective individually, but two or more types of additives may be blended together in some cases.

Further, these compounds can be added to the blending system as they are, but if necessary, they may be added after being dissolved in an appropriate organic solvent.

Next, to explain the blending amount of each raw material of the present invention, the amount of copper powder depends on its shape, particle size, etc., but usually the copper powder, resin binder, and additives that are the constituent components of the composition of the present invention 50 to 98% by weight based on the total amount of, preferably 7
It is 0 to 93% by weight. The amount of additive used depends on the type of compound, but it is usually 0.001 to 0.3 per 1 copper powder.
, preferably a weight ratio of 0.005 to 0.1. If the additive is less than 0.001 with respect to the copper powder, the conductivity will drop significantly, and even if it is more than 0.3, no dramatic improvement in the effect will be seen, but the bring about deterioration.

The composition of the present invention may contain aromatic compounds, esters,
Solvents made of ethers, ketones, and alcohols, reactive diluents having monofunctional groups such as alkyl glycidyl ethers, or polymerizable monomers such as various vinyl monomers can be blended.

The method of curing and shaping the composition of the present invention into a coating film or a molded article includes a known method of curing the resin with the resin binder used.

The temperature at which the composition of the present invention is cured and shaped varies depending on the type of resin binder and additives used, the intended form of use of the composition, etc., but is generally room temperature to 350°C, preferably 50 to 250°C. temperature range is adopted.

When curing the composition of the present invention, for example, polyester resin, polyaryl sulfone resin films or sheets,
A method of coating or printing on a phenolic resin laminate, epoxy resin laminate, polyimide film, etc. and then curing it;
Methods such as pouring into a mold, curing, and molding can be used.

The composition of the present invention has excellent storage stability and can be easily applied to paints, printing inks, adhesives, or molded products such as sheets. In addition, the cured product has excellent conductivity, so it is used in various industries including electrical and electronic fields, such as conductive circuits in printed circuit boards, cross-over circuits, conductive paints for filling through holes, adhesives for electronic parts, etc. It can be used for various purposes.

The present invention will be explained in more detail with reference to Examples below. Note that "parts" and "%" described below mean parts by weight and % by weight, respectively.

Example 1 26 parts of electrolytic copper powder with an average particle size of 10 μm was mixed into an epoxy-melamine resin face (manufactured by Daiyo Kagaku, solid content concentration 50%).
8 parts, tall oil (seed layer chemical, 4JJ fatty acid content 34.7%
, acid value 181) and 4 parts of butylcarpitol, and were thoroughly mixed and dispersed. The coating composition thus obtained was screen printed on a phenolic resin substrate using a zigzag pattern with a width of 211 mm and a length of 368 mm to a film thickness of 60 μm.

Thereafter, it was heated and cured at 160°C for 30 minutes. The resistance of the resulting coating film was measured using a Wheatstone Brisogi, and the length, width, and thickness of the coating film were also measured to calculate the specific resistance value. The resistance and specific resistance values are each 3.5
Ω, 1.0×10 −4 Ωcm. The paint obtained here was stored at about 10°C for one month, but no skinning phenomenon was observed on the paint surface. Furthermore, the above cured coating film was rotated at 60°.
No change in the appearance of the coating film was observed even when it was left in a constant temperature and humidity bath of C195%R■1 for 200 hours.

Comparative Example 1 A copper-containing composition was prepared in exactly the same manner as in Example 1 except that 1.5 parts of phosphorous acid was used instead of tall oil, and then an evaluation test of the composition was conducted. The specific resistance value of the cured coating is 8
．． It was 0×10 −3 ΩcIn.

Furthermore, under the storage conditions of Example 1, this composition exhibited a skinning phenomenon after one day. Furthermore, the above cured coating film was heated to 60°C and 95%
When left in a constant temperature and humidity chamber at RH for 200 hours, bluish-white spots were formed.

Comparative Example 2 A similar test was conducted using 0.34 parts of anthracene in place of the tall oil in Example 1. The specific resistance value is 2゜o x i
It was o-3Ωm. Furthermore, when anthracene-9-carboxylic acid was used instead of anthracene, the specific resistance value was 1.
7×10 −3 Ωcm, which is almost the same as that of anthracene, and in the latter case, under the storage conditions of Example 1, a skinning phenomenon was observed after 2 days.

Comparative Example 3 A similar test was conducted using 1.5 parts of pyrocatechol instead of tall oil in Example 1, and the specific resistance value was 1.2×10
-3Ω mark. Furthermore, under the storage conditions of Example 1, this composition showed a blackish brown skin after one day.

Examples 2 to 3 Rosin (manufactured by Lunar Kasei, softening point 79°C, acid value 168) or pentaerythritol esterified rosin (manufactured by Lunar Kasei, softening point 79°C, acid value 45) was used instead of tall oil in Example 1.
), a copper-containing composition was prepared and evaluated in the same manner. The results are shown in Table 1.

Example 4 A similar test was conducted using oleic acid amide instead of tall oil in Example 1. The results are shown in Table 1.

Example 5 A similar test was conducted using lauric acid amide instead of tall oil in Example 1. The results are shown in Table 1.

Example 6 A composition was prepared and evaluated under the same conditions as in Example 1, except that 6.7 parts of phenolic resin FES (manufactured by Gunei Chemical Co., Ltd., solid content concentration 60%) was used as the resin binder. The results were good as shown in Table 1.

Example 7 A test was carried out in the same manner as in Example 1, except that 0.75 parts of l·-ru oil and 0.75 parts of oleic acid amide were used as additives. The resistance value and specific resistance value of the cured coating film are each 7.
．． 8Ω, 2. It was 1×10 −4 Ω mark m. Further, under the storage conditions of Example 1, this composition did not show any skinning even after one month.

Claims (1)

[Claims] A conductive composition characterized by containing copper powder, a resin binder, and one or more compounds selected from the group of tall oil, rosin, rosin ester, and amides of higher fatty acids as additives.