JPS6129624B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin composition comprising metallic copper powder with improved electrical conductivity, and more particularly to a conductive coating composition having durable electrical conductivity. Resin compositions containing metal powder as a conductor are put to practical use as conductive paints, pastes, adhesives, and conductive resin molded products, and silver, nickel, copper, etc. are used as the metal. gold, palladium,
Precious metals such as silver are stable against oxidation and are preferred because they not only provide excellent conductivity for resin compositions but also maintain stable conductivity over a long period of time. However, these noble metal powders are expensive, and When used for applications such as electromagnetic wave shielding paints and tangible products, which have become a problem, it is difficult to put it into practical use due to cost considerations. Therefore, attempts have been made to use inexpensive metal powders such as nickel and copper, and some of these have been put into practical use. If a conductive resin composition could be developed using copper, which is supplied in large quantities on the market at about one-hundredth of the price of silver, which is one of the cheapest precious metals, it would have great practical value. It's large. However, even when copper powder is in a resin composition, it is easily oxidized, and a non-conductive oxide film is formed on the surface, resulting in a significant tendency for the conductivity of the composition to decrease over time. The product is no longer available. The surface of commercially available copper powder is usually covered with a non-conductive oxide film, so even if it is mixed with resin as is, it will not exhibit electrical conductivity. In addition, when the oxide film on the surface is removed by washing with an acid aqueous solution such as hydrochloric acid and mixed and dispersed in a resin, it initially shows conductivity, but even when left at room temperature for several days, oxidation progresses and the conductivity decreases. be lost. Separately, when a mixture of copper particles and resin is ground into fine powder using a roll or other means to form a metal surface, the composition exhibits conductivity, which is slightly more conductive than the acid treatment described above. Although it exhibits stable conductivity, it gradually loses its conductivity over a long period of time due to the progression of oxidation reactions, making it impossible to obtain satisfactory results. As an effective method for dispersing copper powder in a curable liquid resin to achieve sustained conductivity, a method has been proposed that involves adding a phosphorous acid compound that has the effect of reducing copper compounds such as copper oxide to metallic copper. There is (Tokukai Akira
51-61545, 115691, 1984-145796, 1974-
22449). According to this method, the oxide film on the surface of the copper powder is reduced to metallic copper due to the reducing action of phosphorous acid.
Not only does it impart electrical conductivity to the resin composition, but it also retains its metallic state over time and exhibits sustained electrical conductivity. In this case as well, it was found that the effect of phosphorous acid was not stable over a long period of time, and that conductivity was lost at relatively high temperatures. This is understood to be because phosphorous acid is consumed and converted to phosphoric acid through the oxidation reaction of the copper compound with oxygen, and its reducing ability is lost. The present inventors previously proposed the general formula [] (In the general formula [], X ₁ and X ₂ are halogen atoms,
Alkyl group, cycloalkyl group, aralkyl group,
represents an aryl group, m and n are integers of 0 to 3). The inventors discovered the unique action of the organophosphorus compound represented by the following formula on copper compounds, and invented a resin composition having durable conductivity that contains copper powder to which this compound is added. The organic phosphorus compound of the above general formula [] is
-41009, No. 49-45397, and No. 17979-1979. It has an outstanding stabilizing effect on organic polymer compounds and is used as a stabilizer (for example, 47173, JP 56-50956
Such). The organophosphorus compound is hereinafter referred to as HCA after its trade name. HCA has a unique reactivity with copper compounds. For example, when an HCA alcohol solution is applied to a copper plate whose surface has been oxidized, the copper oxide film is removed and the plate appears as if it had been reduced to metallic copper. According to the present inventors' interpretation, although the phosphorus atom of HCA is pentavalent, it reacts with a copper compound to form a stable complex film, and the copper oxide film is removed at this time. Surprisingly, it has been found that when HCA, a pentavalent phosphorus compound, is applied to non-conductive copper covered with an oxide film, conductivity is exhibited. Copper powder, which does not exhibit conductivity by itself, becomes conductive when cleaned with an alcoholic solution of HCA. Moreover, the conductivity of copper powder is long-lasting, unlike when cleaned with an acid aqueous solution as described above. Conductivity is maintained. Based on such remarkable discoveries, the present inventors have previously invented a method of obtaining a resin composition exhibiting long-term electrical conductivity by incorporating HCA into a composition consisting of copper powder and resin. The present invention further provides a synergistic effect in which the development of conductivity and its sustained effect are further improved by treating copper powder with a combination of HCA and a specific organic titanate compound, or by adding it to a resin composition containing copper powder. It was completed based on the discovery of effectiveness. It has been reported in Japanese Patent Laid-Open No. 1983-1993 that the conductivity of a coating composition containing copper powder can be improved by adding a certain organic titanate compound to the composition.
It is described in Publication No. 36553. The organic titanate compound used for the purpose of the present invention is usually added in an amount of 0.5 to 10% (by weight, the same hereinafter) based on the copper powder. Preferred organic titanate compounds are of the pyrophosphate type and are selected from monoalcosititanate or titanium chelate compounds. Particularly suitable organic titanate compounds include the following. Isopropyl tri(dioctyl pyrophosphate) titanate, titanium di(dioctyl pyrophosphato) oxyacetate, tri(butyl,
octyl pyrophosphate) isopropyl titanate mono(dioctyl, hydrogen phosphite), titanium di(butyl, octyl pyrophosphate)
Di(octyl, hydrogen phosphite) oxyacetate, di(butyl, methyl pyrophosphato) isopropyl titanate mono(dioctyl, hydrogen) phosphite, di(butyl, methyl pyrophosphato) ethylene titanate mono(dioctyl, hydrogen phosphate). Addition of HCA and the organic titanate compound is carried out as follows. 0.5 to 10 parts of HCA was added as a several percent alcohol solution to 100 parts of copper powder (weight, same below), and 0.5 to 10 parts of an organic titanate compound was added, the mixture was stirred, and the solvent was evaporated. After mixing with resin. Alternatively, the method of addition is not particularly limited, such as directly adding HCA and organic titanate compound to a mixture of copper powder and resin and uniformly dispersing them. The organic titanate compound has the effect of promoting uniform dispersion of the copper powder and resin. The remarkable synergistic effect of the HCA and organic titanate compound of the present invention on copper powder is explained as follows. The organic titanate compound acts as a coupling agent when the inorganic filler is mixed and dispersed in the organic resin. The monoalkoxy group of the organotitanate compound reacts on the metal surface to bond to the metal through the alkoxy group and promotes intimate dispersion with the resin matrix through the remaining organic groups. At this time, the copper powder interacts with the aforementioned HCA on the surface of the copper powder to form a conductive coating that is stable against oxidation, and at the same time, a tightly dispersed state of the copper powder and resin is formed. The resin blended into the composition of the present invention is selected depending on the purpose and is not particularly limited. The resin may be in the form of a polymer solid, liquid, solution, monomer, or a mixture thereof, and additives such as pigments and stabilizers may be added. Specific examples include unsaturated polyester resins, acrylic resins, alkyd resins, phenolic resins, amino resins, cellulose resins, urethane resins, epoxy resins, other polymer compounds such as petroleum resins, and silicone resins. These resins may be in any form such as a solution type using an organic solvent, a 100% liquid resin type containing a monomer, or a solid resin type. As the copper powder used in the present invention, a commercially available metal powder may be used as is, or granular copper may be mixed with a resin component and ground with a ball mill or roll. The mixed composition of copper powder and resin to which HCA and an organic titanate compound are added can be produced by a commonly known method depending on the purpose and use of the composition. For example, for the purpose of obtaining a conductive coating material, a kneading machine such as a ball mill or a three-roll mill is used, and the production of a conductive adhesive is also carried out by the same means. Further, when obtaining a film or sheet-like conductive molded article, a molding means such as a calender roll, an extruder, or a hot press is selected. Next, examples of the present invention will be described. Example 1 This example describes preliminary experiments to learn the effects of HCA and organic titanate compounds. 100 parts of copper powder (commercially available 325 mesh pass) was placed in a container, and conductivity was examined using a tester, but no conductivity was observed. Next, add 5% of this copper powder
Wash with a water-methanol (1:1) solution of hydrochloric acid,
Furthermore, those washed with acetone and dried showed conductivity, but the conductivity was lost after being left at room temperature for 2 days. On the other hand, 9,10-
Cyclhydro-9-phosphor-10-oxaphenanthrene-9-oxide (hereinafter referred to as H-HCA)
100 parts of a 4% methanol solution was added and mixed, and the solvent was evaporated and dried under reduced pressure.
Furthermore, the same conductivity was exhibited even after leaving it at room temperature for one week. A similar experiment was conducted using a methanol solution containing H-HCA and the same amount of titanium di(dioctylpyrophosphate) oxyacetate, and the results showed similar conductivity. On the other hand, when similar treatment was performed using only the same organic titanate, no conductivity was observed. The following compound was used in place of H-HCA in Example 1 and tested in the same manner, and similar results were obtained. 9,10-dihydro-1-cyclohexyl-9-
Phosphor-10-oxaphenanthrene-9-oxide. (abbreviated as 1-CH-HCA) 9,10-dihydro-3-(α,α-dimethylbenzyl)-9-phosphor-10-oxaphenanthrene-9-oxide. (abbreviated as 3-DMB-HCA) 9,10-dihydro-3-t-butyl-9-phosphor-10-oxaphenanthrene-9-oxide. (abbreviated as 3-B-HCA) Example 2 80 parts of phenolic resin (Bryauphene 5010 manufactured by Dainippon Ink, non-volatile content 60%), H-HCA4
A solution prepared by dissolving 6 parts of di(butyl, methyl pyrophosphato) isopropyl titanate mono(dioctyl, hydrogen) phosphite in 30 parts of ethanol was added, and 150 parts of the same copper powder as in Example 1 was added thereto.
The mixture was premixed at room temperature, left to stand for 4 hours, and then uniformly kneaded using three rolls to prepare a coating composition. On the other hand, as Comparative Example 2-1, no titanate compound was added, and as Comparative Example 2-2, H-HCA
Samples were prepared in the same manner as in Example 2, except that no . These compositions were placed on a glass plate with a width of 10 mm and a length of
Apply to 100mm and heat dry at 90℃ for 30 minutes, then apply 120mm
It was cured by heating at ℃ for 2 hours to form a cured coating film with a thickness of 100μ. The conductivity of these samples was measured using a Whistone double bridge resistance meter to determine the specific resistance. The results are shown in Table-1.

[Table] Instead of H-HCA in Example 2, 1-CH-
A similar test was conducted using HCA.3-DMB-HCA or 3-B-HCA, and similar results were obtained. Example 3 A solution prepared by dissolving 5 parts of H-HCA and 5 parts of isopropyltri(dioctylpyrophosphate) titanate in 30 parts of methanol was added to 100 parts of the same copper powder as in Example 1, stirred uniformly, and then kept at room temperature for 5 hours. After standing, methanol was evaporated with warm air. Acrylic resin (Acryloid B manufactured by Rohm and Haas)
-66) 60 parts was dissolved in 30 parts of toluene and 10 parts of ethanol, and then 70 parts of the copper powder treated above was added and kneaded in the same manner as in Example 2 to prepare a coating composition. On the other hand, as Comparative Example 3-1, no titanate compound was added, and as Comparative Example 3-2, H-HCA
Samples were prepared in the same manner as in Example 3, except that no . These preliminary compositions were applied to a glass plate in the same manner as in Example 2, and dried at 90° C. for 30 minutes and then at 120° C. for 2 hours to form a coating film with a thickness of 100 μm. The conductivity test was conducted in the same manner as in Example 2. The results are shown in Table-2.

【table】

Claims (1)

[Claims] 1. In a resin composition containing metallic copper powder as a conductor, the general formula [] (In the general formula [], X ₁ and X ₂ are halogen atoms,
Alkyl group, cycloalkyl group, aralkyl group,
1. A resin composition with improved conductivity, characterized by containing an organic phosphorus compound and an organic titanate compound (representing an aryl group, m and n are integers of 0 to 3).