JPH0135444B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a conductive composition having good initial conductivity and sufficient conductivity durability under high humidity. As a result of research to obtain a cured resin with good conductivity using metallic copper powder, the present inventor found that (a) metallic copper powder, (b)
A composition containing a copper compound, (c) a reducing part that can generate metallic copper by reducing copper in the copper compound (hereinafter abbreviated as the reducing part), and (d) a resin part is electrically conductive. It has been found that a good cured resin can be obtained. In this case, when an organic or inorganic phosphorous compound such as a mono- or diester of phosphorous acid is used as the reducing moiety, it is possible to obtain a cured resin with particularly excellent initial conductivity. be. However, it has been found that when this cured resin is stored for a long time at high temperature and high humidity, a verdigris-like substance is generated on the surface of the cured resin, and the conductivity gradually decreases over time. In general, in electrical applications, it is highly desirable that the resistance value hardly increases even when stored under high temperature and high humidity, and even if it does increase slightly, it is highly desirable that once the resistance value reaches a certain value, it will not change substantially after that. Rare and verdigris-like materials are also not preferred as they impair electrical properties and appearance. For this reason, it has been difficult to put such cured resins into practical use in applications with high requirements. For this reason, the inventor of the present invention has found that when the initial conductivity is good, and even when stored under high temperature and high humidity, no patina-like substance is generated, there is little decrease in conductivity, and furthermore, when a certain resistance value is reached, Thereafter, as a result of searching for a composition that would yield a cured resin with substantially unchanged conductivity, the present invention, which achieved this goal, was completed. The present invention includes (a) metallic copper powder, (b) copper compound, and (c) reducing moiety.

[Formula] and

A moiety with a structure selected from the group consisting of [Formula] (hereinafter abbreviated as dihydroxybenzene ring moiety.However, those from urushiol are excluded), and (d) a resin moiety, or furthermore, it has ( e) Contains a chelate-forming substance part, and the content of part (c) is 80% by weight, based on the amount sufficient to reduce all the copper in the copper compound.
This is a conductive composition characterized by containing the above components. In the case of compositions that do not contain part (e) in the present invention, although the mechanism is unknown, the storage stability of the composition is poor, and as the storage time elapses, it comes into contact with air. This tends to harden the surface of the composition, impairing its quality, and eventually rendering it unusable (hereinafter abbreviated as scalding phenomenon). If this scalding problem cannot be solved, in order to put the composition of the present invention into practical use, it will be necessary to use it immediately after preparation, which is inconvenient for applications that require long shelf life. As a result of intensive investigation, we found that by adding (e), the parenchymal epithelial burr phenomenon could be prevented, although the mechanism is also unknown. The shape of the metallic copper powder used in the present invention is not particularly limited, and examples thereof include flakes, dendritic shapes, spherical shapes, and irregular shapes. In addition, pulverized metallic copper (including foil), reduced copper powder obtained by reduction of cupric oxide or cuprous oxide, copper powder obtained by scattering and solidifying molten copper, electric Analysis of copper powder and these methods 2-3
Copper powder etc. obtained by combining types can be used.
The particle size is usually 100μ or less, but depending on the purpose, particles of 100μ to 1mm can also be used. Note that the metallic copper powder may be a normal commercially available copper powder in which cuprous oxide or cupric oxide, which are examples of copper compounds described later, is present as a film on the surface, or one in which no copper compound is present. is also available. Of course, metallic copper powders having different shapes and particle sizes may also be mixed and used. In addition, although the expression "resin part" is used in this application, the resin has the following meaning. That is, it is a material that has already become a polymer before it is finally cured, or a material that becomes a polymer material through a reaction during curing, and when the composition of the present invention is cured, it becomes conductive. It means a substance from which a cured product can be obtained. The composition of the present invention needs to contain (b), (c), and (d) in addition to (a), or further include (e),
It is not necessary to use four or five separate substances corresponding to (a), (b), (c), (d), (e), for example (c) and ( (a), (b), (c), (d), (e), such as using a resin with a dihydroxybenzene ring that also serves as d).
By using a substance that also serves as some of the
It is also possible to achieve the objective simply by mixing three or two types of substances. Hereinafter, various substances used in the present invention will be explained by giving examples. (1) Copper compounds having only the properties specified in (b) Cuprous chloride, cuprous oxide, cupric oxide, copper acetate, copper salicylate, copper stearate. (2) Substances having only the properties of (c) with a dihydroxybenzene ring: Hydroquinone, catechol, 2-methyl-
Hydroquinone, vinylhydroquinone, tertiarybutylhydroquinone, chlorohydroquinone, phenylhydroquinone, and other substances with the following structures.

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] (3) Resin, that is, a substance that has only the properties as (d) Uria formaldehyde resin, melamine
Formaldehyde resin, phenol-formaldehyde resin, unsaturated polyester resin, thermosetting saturated polyester resin, polycarbonate resin, polyphenylene oxide resin, polyphenylene sulfide resin, fatty acid alkyd resin, polyamide resin, polyimide resin, epoxy acrylate resin , aryl resin (diallyl phthalate resin, etc.), epoxy resin, urethane resin, polyoxymethylene resin, spiroacetal resin, silicone resin, polysulfide rubber, acrylic resin, styrene resin, olefin resin, vinyl alkanoate resin, butadiene rubber , isobutylene rubber, ethylene-propylene rubber, chloroprene rubber, epchlorohydrin rubber, cellulose resin, rosin resin, fluorine resin, phosphonitrile chloride resin, ethyl silicate polymer. (4) a copper compound having a dihydroxybenzene ring,
That is, a substance that serves both (b) and (c); a copper salt of the substance in item (2) above;

Copper salt of [formula]. (5) Resin-like copper compounds, i.e. substances that serve as both (b) and (d) Copper salts of saturated or unsaturated polyester resins, copper salts of vinyl chloride-vinyl acetate-maleic acid copolymers, sulfoethyl methacrylate-ethyl acrylate Copper salt, copper salt of rosin resin. (6) Resin having dihydroxybenzene ring, i.e.
Substances that serve both (c) and (d) Vinyl hydroquinone polymers and copolymer resins, hydroquinone-formaldehyde phenolic resins, hydroquinone-phenol-formaldehyde phenolic resins, catechol-formaldehyde phenolic resins,
1,4-dihydroxynaphthalene-formaldehyde resin. (7) A resinous copper compound having a dihydroxybenzene ring, that is, a substance that also serves as (b), (c), and (d): a copper salt of a vinylhydroquinone-methacrylic acid copolymer, the copper salt of item (6) above. (8) Chelate-forming substances, that is, substances exhibiting properties as (e) Chelate-forming substances suitable for the present invention include:
The logarithm value of the stability constant Kma for divalent copper ions is 3 or more at 25°C and ionic strength 0.1,
Preferably, 5 or more are used. These substances include the following: 8-1 Aliphatic amines and their derivatives Ethylenediamine, N-(2-hydroxyethyl)ethylenediamine, trimethylenediamine, 1,2-diaminocyclohexane,
Triethylenetetramine, 2-aminomethylpyridine. 8-2 Aromatic polyamine Purine, adenine, 2-aminomethylpyridine, histamine. 8-3 β-diketone acetylacetone, trifluoroacetylacetone, 4,4,4-tolufluoro-1-
Phenyl-1,3-butanedione, hexafluoroacetylacetone, benzoylacetone, dibenzoylmethane, 5,5-dimethyl-1,3-cyclohexanedione. 8-4 Phenolic compounds oxine, 2-methyloxine, oxine-5-sulfonic acid, dimethylglyoxime,
1-Nitroso-2-naphthol, 2-nitroso-1-naphthol, salicylaldehyde. 8-5 Others 2,2'-dipyridyl, 1,10-phenanthroline. Among the above-mentioned chelate-forming substances, the above-mentioned 8-3 and 8-
The substances exemplified in 4 and 8-5 are preferred, and among them, acetylacetone, 4,4,4-trifluoro-
1-phenyl-1,3-butanedione, benzoylacetone, dibenzoylmethane, 5,5-dimethyl-1,3-cyclohexanedione, oxine, oxine-5-sulfonic acid, dimethylglyoxime, 1-nitroso-2-naphthol , salicylaldehyde, 2,2'-dipyridyl, and 1,10-phenanthroline are particularly preferred. Of course, it is also possible to use substances that have the properties of (e) and other properties such as (b), (c), and (d). The proportion of the copper compound used in the present invention is 0.1 to 30% by weight as the copper content of the copper compound to the metal copper powder,
The content is preferably 0.2 to 10% by weight. The proportion of the dihydroxybenzene ring used in the present invention is preferably 80% by weight or more, particularly preferably 95% by weight or more, based on the amount sufficient to reduce all the copper in the copper compound. There is no particular restriction on the upper limit, but generally the proportion of non-volatile components excluding the metallic copper powder used in the present invention is 95% by weight.
It is as follows. The proportion of the resin part used in the present invention is from 5 to 50% relative to the total non-volatile content of the composition used in the present invention.
60% by weight, preferably 8-45% by weight. In addition, among the substances (c) and (c) that are suitable for the present invention, that is, the substances (2), (4), (6), and (7), which are combined with (d), Particularly preferable are substances such as (6) and (7) above, in which (c) is used in a certain form.If substances in other forms, such as (2) and (4), are used, the conductive properties of the present invention are After curing the composition, when performing soldering in practical applications, 260
No abnormalities are observed when immersed in a solder bath at 300°C for about 10 seconds, but under severe conditions such as immersion in a solder bath at 300°C for 10 seconds, abnormalities such as blistering may occur. The resin used as the resin part in the present invention may be solid in itself, but it must not become substantially or apparently liquid by itself or in the presence of an organic solvent, water, plasticizer, etc. during curing. Good to have.
Usage forms of resin include solvent type dissolved in organic solvent, water soluble type, water emulsion type, solvent emulsion type, 100% liquid resin type, and 100% solid resin type that becomes liquid at the temperature during curing. Any of the following may be used, and there is no particular restriction. The following methods may be used to cure each of these resins. That is, if these are cured while evaporating volatile substances by drying, such as room temperature drying type resins (Latzker type), or if they have (a) thermosetting properties, depending on the type, ( 1) cured by heat or (2) for resins cured by vinyl polymerization, such as unsaturated polyester resins and acrylate resins, azobisisobutyronitrile, di-t-
In the case of epoxy resins, triethylenetetramine, polyamide polyamine, diaminodicyclohexylmethane, diaminodiphenylmethane, adipic acid dihydrazide, imidazole derivatives, dicyandiamide, etc. , boron trifluoride/ethylamine complex,
Using known curing agents such as polymercapto compounds, polyhydric carboxylic acids and their anhydrides, hexamethylenetetramine in the case of phenolic resins,
By using a curing agent or curing accelerator such as paraformaldehyde or P-toluenesulfonic acid, or in the case of an oxidative curing type resin, by using a known dryer such as lead naphthenate or cobalt octylate. , (b) for thermoplastics,
What is necessary is just to harden by a well-known means, respectively, by cooling after heating. In short, the resin may be cured by any known means depending on the type and nature of the resin. Note that the reducing action in the present invention is preferably exerted at the stage of curing the resin, and if this reduction reaction is too rapid or slow compared to the curing, the purpose obtained by the method of the present invention may be impaired. Since it affects the durability of the conductivity of the material, the reduction temperature is usually set at
The temperature is 250°C or less, preferably room temperature to 200°C, particularly preferably 50°C to 180°C. Therefore, a substance containing a dihydroxybenzene ring moiety, a metallic copper powder, a copper compound, a resin, a basic substance, etc. may be selected so as to satisfy such conditions. Incidentally, it is preferable that a basic substance such as a substance containing an amino group be present in the composition of the present invention. Further, in the present invention, the atmosphere in which the reducing action is caused may be any atmosphere such as nitrogen, an inert gas such as carbon dioxide, or air, and there is no particular restriction on the atmosphere. When curing the resin in the method of the present invention,
Various known additives such as those listed below may be added in advance. For example, molecular weight regulators such as mercaptopropionic acid, carbon tetrabromide, stabilizers such as P-benzoquinone, phenothiazine, reactive diluents such as butyl glycidyl ether, phenyl glycidyl ether, dibutyl phthalate, tricresyl phosphate, etc. Noble metals belonging to group B and groups of the periodic table such as gold, silver, palladium and their compounds, inorganic bases such as lithium hydroxide, potassium hydroxide, dimethylbenzylamine, ethanolamine, tris(N,N - amino compounds such as (dimethylaminomethyl)phenol, N,N-dimethylaniline, acids such as acetic acid, oxalic acid, benzoic acid, pH regulators such as sodium orthophosphate, borax, potassium acetate, polyvinyl alcohol, polyvinylpyrrolidone. Viscosity modifiers such as potassium oleate,
Surfactants such as sodium dodecylbenzenesulfonate, polyoxyethylene lauryl ether, and tadecyl pyridinium chloride, solvents such as water, toluene, methyl ethyl ketone, and ethylene glycol monoethyl ether, paraffin wax, carbon black, methyl ethyl ketoxime, and lubricants. , flame retardants, colorants, blowing agents, thixotropic agents, etc. When curing the composition of the present invention, various substrates such as polysulfone resin sheets, phenolic resin laminates, epoxy resin laminates, polyimide films, organic materials such as non-woven fabrics, glass, inorganic materials such as alumina, painted iron plates, coatings, etc. It may be applied or printed on an aluminum plate or the like and cured, or it may be formed by placing it in a mold. The conductive cured product obtained by curing the composition of the present invention may be subjected to various known protective treatments as described below, taking into consideration the intended use, environment of use, enhancement of reliability, etc. That is, such treatments include electrical or chemical plating with nickel, copper, etc., coating with epoxy resin, phenolic resin, rosin-based substances, polyethylene film, etc., surface treatment with imidazole-based processing agents, silicone-based processing agents, etc. There is. The composition of the present invention can be used in paints, adhesives, printing inks, molded products, etc. In the electrical and electronic industrial fields, it is used in conductive circuits, crossover circuits, high frequency protection circuits, heat dissipation circuits, and through-hole parts. It has a wide range of practical applications, such as filling, adhesion of parts, etc. in the automobile industry, dew condensation prevention circuits on windows, and heaters in the housing field, and is extremely useful industrially. One example of the application of the composition of the present invention is printed circuit boards by screen printing; in this case, compared to conventional silver-based printing inks, there is no short circuit between circuits due to so-called silver migration. Enhances the practical value of the present invention. Examples will be described below. Parts and % hereinafter mean parts by weight and % by weight, respectively, and concentrations described in the examples represent the proportion of the component in all components in % by weight. The "printed material by screen printing method" in the examples described below was formed by the following method. An S-shaped linear printing material having a total length of 200 mm and a width of 0.5 mm with an interval of 0.5 mm was formed on the surface of the printing material by the following method. That is, a film was made using a straight line method using a photographic engraving method on a 180-mesh Tetron screen so that the film thickness of the entire screen was 145 μm, and the structure was such that the screen was closed except for the necessary image lines. A screen for screen printing was created, and the conductive composition used in each experiment was adjusted to rubber hardness No.
After hand-printing onto the printing surface using a squeegee using No. 70 urethane rubber, the printed material was shaped by curing under the curing conditions of each experiment. In addition, the resistance value and specific resistance value listed as a guide for conductivity are measured using a tester (manufactured by Yokogawa Electric Corporation, Type
-3201), Wheatstone Bridge (manufactured by Yokogawa Electric Corporation,
Type-2755) was used to contact both ends of the cured product of the printed material to measure the resistance value, and the thickness, length, and width of the cured product were measured to calculate the specific resistance value. The durability tests in the examples described below were carried out using a constant temperature and humidity tester (ETAC's tabletop temperature and humidity tester JLH).
-400-40 type) under the conditions of 50℃, RH95%, and 1000 hours. After each time, the printed material was taken out and left at room temperature for 1 hour, and the resistance value and appearance changed. was measured. Example 1 Each of the liquid compositions obtained in Experiments 1 and 2 below was printed by the above-mentioned "screen printing method" on the surface of each of six glass plates (thickness 1.7 mm) whose one surface had been cleaned with ethyl acetate. Each printed body obtained in this way was pre-dried at 100℃ for 20 minutes in a thermostat in an air atmosphere, and then the experimental number was -1
For printed matter, heat cure at 150℃ for 60 minutes,
For the printed bodies of experiment numbers 2, 3, 4, 5, and 6, the cured coatings obtained by heating and curing at 165℃ for 90 minutes were left to cool at room temperature, and the resistance and specific resistance values of each were measured. Subsequently, the same test specimen was subjected to a durability test, and the results are shown in Table 1. Experiment number-1 (comparative example) (a) Industrial copper powder (amorphous, average 15μ, copper oxide approximately 2.0
(b) 23 parts of alcohol-soluble resol-type phenolic resin (resol-type phenolic resin obtained from 1 mole of phenol and 3 moles of formalin) with a nonvolatile content of 80% after curing, (c) 2- Hydroxy-3-phenoxypropyl phosphite 20
(iv) 4 parts of dimethylaminoethanol, (e) 29 parts of a mixed medium consisting of diacetone alcohol and ethylene glycol monomethyl ether (1:1), and (f) 2 parts of acetic acid. Experiment No. 2 (Example of the present invention) (a) 110 parts of industrial copper powder (amorphous, average particle size 15μ, containing about 2.0% copper oxide), (b) 80% resin dissolved in ethylene glycol monobutyl ether 42 parts of hydroquinone-modified resol type phenolic resin (obtained by reacting 2 moles of hydroquinone, 0.5 moles of phenol, and 6 moles of formalin in the presence of an ammonia catalyst), (c) tris(NN'-dimethylaminomethyl)phenol 0.2 parts, (d)ethyl acetoacetate
A liquid composition made by mixing 12 parts. Experiment No. 3 (Example of the present invention) (A) and (B) of Experiment No. 2 above are the same; (C) is 0.5 part of N,N'-dimethylaniline; (D) is 4;
4,4-trifluoro-1-phenyl-1,3-
A liquid composition consisting of 8 parts of butanedione and 5 parts of (e)diethylene glycol monomethyl ether. Experiment No. 4 (Example of the Present Invention) A liquid composition comprising 5 parts of 2,2'-dipyridyl as (d) in Experiment No. 3 above, and the same composition. Experiment No. 5 (Example of the present invention) (a) 25 parts of industrial flaky copper powder (average particle size 20μ, copper oxide content approximately 3.5%) and industrial electrolytic copper powder (average particle size 15μ, copper oxide content) 0.5%), (b) 10 parts of methylated methylolmelamine resin, (c) 7 parts of catechol, (d) 18 parts of 2-methylhydroquinone, (e) 15 parts of diethylene glycol monomethyl ether, (f) hexamethylene. 2 parts of tetramine, (g) industrial silver powder (wood)

[Table] A liquid composition made by mixing 10 parts of branched, average particle size 1μ). Experiment No. 6 (Example of the Present Invention) A liquid composition obtained by further adding 10 parts of acetylacetone to the composition of Experiment No. 5 above. Experiment No.-7 (Comparative Example) In Experiment No.-5, instead of 7 parts of catechol and 18 parts of 2-methylhydroquinone, 0.01 part of catechol (based on methylolated melamine resin) was used.
A liquid composition was obtained in the same manner as Experiment No. 5 except that 1000 ppm ^* ) was used, and then printed by screen printing and heat cured in the same manner as Experiment No. 5. When the initial resistance value (Ω) was measured, it was ∞, and no conductivity was observed. The reason for this is thought to be that the copper oxide on the surface of the copper powder was not reduced due to the small amount of the reducing agent catechol added. ( ^*
About the amount of reducing agent to reduce copper in the copperide used.
(equivalent to 0.5% by weight) In Table 1, the presence or absence of the scalding phenomenon of the liquid composition means that 100 parts of the liquid composition obtained in each experiment number was placed in a wide-mouth glass bottle with an internal volume of 100 ml, the bottle was tightly stoppered, and the liquid composition was left standing. This is the result of observing changes over time. Furthermore, in Example 1, the liquid compositions of experiment numbers -2 and -5 were used instead of the glass plate.
After screen printing and heat curing on the surface of a 1.5 mm epoxy resin laminate using the method described above, it was immersed in a 260°C solder bath for 10 seconds.
The conductive cured products obtained from Experiment No. 2 and -5 did not cause any abnormalities such as blistering, but when separately immersed in a 300°C solder bath for 10 seconds,
No abnormality occurred in the conductive cured product obtained from the composition of experiment number-2, whereas experiment number-2
Slight blistering occurred in the conductive cured product obtained from composition No. 5. Example 2 In the composition of Experiment No. 2 of Example 1, (d) instead of 12 parts of ethyl acetoacetate, a liquid composition was prepared by mixing chelate-forming substances of the type and amount shown in Table-2. Example 1 was used except for the heat curing conditions.
A cured coating film was prepared in the same manner as in Example 1 and tested in the same manner as in Example 1. Table 3 shows the test results and the heat curing conditions for producing the cured coating. Furthermore, the table-
In the liquid compositions of Experiment Nos. 14 and 15 of 12, ethylene glycol monobutyl ether was not added.

【table】

【table】

Claims (1)

[Claims] 1 (a) Metallic copper powder, (b) copper compound, (c)
[Formula] Contains a part with a structure selected from the group consisting of A conductive composition characterized by containing 80% by weight or more of copper, based on an amount sufficient to reduce all of the copper. 2 (a) Metallic copper, (b) copper compound, (c)
Contains a part with a structure selected from the group consisting of [Formula] (excluding those from urushiol), (d) a resin part, and (e) a chelate-forming substance part, and a combination of the above (c) part. The amount is based on the amount sufficient to reduce all the copper in the copper compound,
A conductive composition characterized by containing 80% by weight or more.