JPS6114175B2 - - Google Patents

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 serious drawback in this case is that the copper powder dispersed in the binder is highly oxidizable, so the surface of the copper powder may be oxidized during storage as a composition, during the formation of a coating film, etc., or during its use. As a result of the increased contact resistance between powder particles, sufficient electrical conductivity is not exhibited and it is difficult to maintain electrical 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
24936), anthracene or its derivatives (JP-A-56-103260), hydroquinone derivatives (JP-A-57-55974), and the like. However, according to research conducted by the present inventors, copper-containing conductive compositions containing these additives suffer from a so-called skinning phenomenon in which the surface hardens and quality is impaired.
There are some drawbacks in terms of storage stability, and 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. Furthermore, if the cured product is stored for a long time under high temperature and high humidity, a verdigris-like substance will form on the surface of the cured product and the electrical conductivity will drop significantly. There were very few additives. The present invention has been made to eliminate the drawbacks of the prior art described above, and its objectives are to provide a composition with good storage stability, excellent conductivity, and poor appearance such as rust on the surface of the cured product. It is an object of the present invention to provide a copper-containing conductive composition that does not cause. The present inventors have discovered that it is extremely effective for the above purpose 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, and to make the compound coexist with the system. Completed the invention. That is, the present invention provides a conductive material containing 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 sexual composition. The copper powder used in the composition of the present invention includes:
Examples include reduced copper powder obtained by reducing copper oxide or the like, 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. It is also possible to use a mixture of two or more of these various copper powders. The particle size of these copper powders is
It is selected depending on the intended use of the composition, but generally
A material having a diameter of 300 μm or less, preferably 1 to 100 μm is suitable. 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 are already turned into polymeric substances before being finally cured. It also includes substances that can be turned into polymeric substances through a curing reaction. Specifically, phenolic resins, epoxy resins, polyimide resins, and urethane resins may be mentioned, but radically polymerizable resins are not included. 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 production of kraft pulp from coniferous wood, and contains resin acids mainly consisting of abietic acid and its isomers, fatty acids consisting of oleic acid and linoleic acid, etc. include. Tall oil is a dark brown oily substance whose composition generally ranges from 25 to 55% by weight of resin acids and from 30 to 60% by weight of fatty acids, but any composition can be used for the purpose of the present invention. Rosin includes gum rosin, which is obtained by distilling turpentine oil from raw pine resin collected by directly cutting pine trees, udon rosin, which is obtained by cutting pine roots into chips and extracting the rosin with a solvent, and furthermore, by precision fractionation of crude tall oil. All of them contain a mixture of abietic acid and its isomers as a main component (80 to 97% by weight). Any of these various rosins having different compositions can be suitably used in the composition of the present invention. Furthermore, in order to eliminate conjugated double bonds in resin acids that are active against radical species, heat treatment at high temperatures using noble metal catalysts, hydrogenated disproportionated rosin, hydrogenated rosin, or heat treatment in the presence of acidic catalysts is performed. Polymerized rosin etc. obtained by this method can also be used similarly. Furthermore, various rosin esters can be used as additives in the composition of the present invention. Rosin ester (esterified rosin) is produced by reacting abietic acid, which is the main component of rosin, and its isomers with monohydric or polyhydric alcohols at high temperatures. For example, methyl esterified rosin, monoethylene glycol esterified rosin, etc. , diethylene glycol esterified rosin, glycerin esterified rosin, pentaerythritol esterified rosin, and the like. In addition to the above-mentioned rosins and rosin esters, various modified rosins obtained by adding maleic anhydride, fumaric acid, acrylic acid, cyclopentadiene, etc. to the rosin by the Deyl-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. Especially carbon number 10
Amides derived from ~24 higher fatty acids exhibit excellent effects. Specifically, lauric acid amide, myristic acid amide, palmitic acid amide,
Examples include 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 a suitable 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 copper powder, which is a component of the composition of the present invention,
50 ~ based on the total amount of resin binder and additives
98% by weight, preferably 70-93% by weight. The amount of additive used depends on the type of compound, but is usually 0.001 to 0.3, preferably 0.005 to 0.1 per 1 copper powder.
Good weight ratio. When the additive amount is less than 0.001 with respect to copper powder, the conductivity decreases significantly, and
Even if the above-mentioned methods are used, not only no dramatic improvement in effectiveness is observed, but also the heat resistance or moisture resistance life characteristics deteriorate. The composition of the present invention may contain aromatic compounds, depending on the usage form, required performance, or for the purpose of improving workability.
Solvents made of esters, ethers, ketones, 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. The composition of the present invention can be cured by, for example, coating or printing on a film or sheet of polyester resin, polyarylsulfone resin, phenol resin laminate, epoxy resin laminate, polyimide film, etc., and then curing it, or by pouring it into a mold. Methods such as curing and molding can be used. The composition of the present invention has excellent storage stability, and can be used as a paint,
It can be easily applied to printing inks, adhesives, or molded products such as sheets. In addition, the cured product has excellent conductivity, so it can be used for electrical applications 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 in various industrial fields including the electronic field. 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 with 8 parts of epoxy-melamine resin varnish (manufactured by Ohashi Kagaku, solid content concentration 50%), tall oil (manufactured by Harima Kasei, resin acid content
34.7%, acid value 181) and 4 parts of butyl carbitol, 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 2 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 Bridge, 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 were 3.5Ω and 1.0×10 ⁻⁴ Ωcm, respectively. 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 was kept at a constant temperature of 60℃ and 95%RH.
No change in the appearance of the paint film was observed even after being left in a humidity chamber 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 in place of the tall oil, and then an evaluation test of the composition was conducted. The specific resistance value of the cured coating film was 8.0×10 ^-3 Ωcm. Furthermore, under the storage conditions of Example 1, this composition exhibited a skinning phenomenon after one day. Furthermore, the above cured coating film
When left in a constant temperature and humidity chamber at 60°C and 95% RH for 200 hours, bluish-white spots were formed. Comparative Example 2 Anthracene instead of tall oil in Example 1
A similar test was conducted using 0.34 parts. The specific resistance value is
It was 2.0×10 ^-3 Ωm. 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 Pyrocatechol instead of tall oil in Example 1
When a similar test was conducted using 1.5 parts, the specific resistance value was
It was 1.2×10 ^-3 Ωcm. Further, when this composition was stored under the storage conditions of Example 1, a blackish brown skin was observed after one day. Examples 2 to 3 Rosin (manufactured by Harima Kasei, softening point 79°C, acid value 168) or pentaerythritol esterified rosin (manufactured by Harima Kasei, softening point
A copper-containing composition was prepared and evaluated in the same manner using a temperature of 79°C and an acid value of 45). 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 varnish (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 conducted in the same manner as in Example 1 except that 0.75 part of tall oil and 0.75 part of oleic acid amide were used as additives. The resistance value and specific resistance value of the cured coating film were 7.8Ω and 2.1×10 ^-4 Ωcm, respectively. Furthermore, under the storage conditions of Example 1, this composition did not show any skinning even after one month. 【table】

Claims (1)

[Claims] 1 Copper powder 70 to 90 with an average particle size of 1 to 100 μm
tall oil, rosin, diethylene glycol or glycerin rosin ester and Carbon number 10~
at least one selected from the group of 20 fatty acid amides
A conductive composition comprising 0.1 to 30% by weight of seeds added to copper powder.