JP3418555B2 - Coated metal particles and toner for electrophotography using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to polymer-coated metal particles and an electrophotographic toner using the same. In particular,
TECHNICAL FIELD The present invention relates to polymer-coated metal particles that can be used as a toner used when forming an electric circuit wiring or a metal pattern formed on a ceramics sintered body by electrophotography.

[0002]

2. Description of the Related Art Conventionally, a printed wiring board has been prepared by coating a photosensitive material on a substrate such as a phenol resin on which a conductive foil such as copper is stretched,
It was produced by using an optical photomechanical technique in which the photosensitive material was exposed to a predetermined pattern, baked, and then etched.

However, the production of a wiring board by such an optical photolithography technique is problematic because it involves a large number of steps and the subsequent waste liquid treatment involves complicated etching and cleaning steps.

Further, electrodes or conductor wirings for semiconductor integrated circuits, electronic parts, etc. have been generally produced by screen printing and firing a so-called "thick film paste". This thick film paste is made of fine particles of glass such as lead borosilicate glass and Au, Pt, Pd.Ag, Pt.
It is prepared by mixing a fine metal powder such as Ag, Cu or Ni with an appropriate ratio and dispersing the mixture in a vehicle composed of an organic binder, a plasticizer, a solvent and the like.

However, in the preparation of such a thick film paste, a high shearing force is applied under high viscosity, but the agglomerated fine particle metal powder is not easily dissociated into primary particles and the dispersibility is poor. Will be enough. Even if the paste having such non-uniform dispersion of metal fine particles is printed and then fired, a dense and smooth metal film is not formed, and the sintering temperature characteristic originally depends on the particle size of the metal powder. Fluctuates greatly due to the influence of agglomerated particles, causing variations, making it difficult to form a metal film at an appropriate sintering temperature, causing the electrical characteristics of the metal film to fall below the set values, and the mechanical strength of the metal film. Or a decrease in the bonding strength between the base material and the metal film has been a problem.

In recent years, as an alternative to the production of a printed wiring board by the above-mentioned optical photomechanical process, by utilizing electrophotographic technology, a dry method which does not include a problematic etching step or cleaning step, that is, exposure is performed. A technique for forming a printed circuit wiring pattern in three steps of developing, transferring and transferring has also been proposed (Chemical Review, No. 48 (1)
985), "Ultrafine particles-science and application", edited by The Chemical Society of Japan,
Published by Academic Publishing Center, page 149).

This is because the electrophotographic photosensitive layer on the photosensitive plate is first charged, the circuit original plate is irradiated and exposed to form this optical image on the photosensitive layer by electrostatic charging, and then the electrophotographic developing method is used. Toner is attached to this optical image portion to form a conductor pattern. The toner used has a particle size of 3 to 10 μm.
Mixtures of m Pb, Sn or alloys thereof with thermoplastic resin powders such as polystyrene or acetyl cellulose are used. After that, a printed circuit board obtained by coating a substrate such as Bakelite or acrylic resin with a thermoplastic resin is brought into close contact with a photosensitive plate having the conductor pattern formed on the surface and heated, thereby transferring and fixing toner to the printed circuit board. This ends the circuit production.

However, since the toner used in such a method is conventionally obtained by simply mixing and pulverizing fine metal particles and a thermoplastic resin as described above, the dispersibility of the fine metal particles in the toner particles varies. However, the electrical characteristics of the conductor circuit formed by fixing such toner particles may not be at a satisfactory level. Further, since there is a large variation in the amount of the thermoplastic resin present on the surface of the toner particles, whether or not the metal particles are exposed, the charging characteristics of the toner in the electrophotographic method are not sufficient, and the reproducibility of the image, It also causes problems in resolution, etc. Furthermore, since the metal particles and the thermoplastic resin are only physically attached, the mechanical strength of the toner particles is not sufficient, and the toner particles are not easily transferred or triboelectrically charged. In such cases, the metal particles and the thermoplastic resin may be separated from each other to further deteriorate the characteristics.

Further, in JP-A-8-259844, at least one selected from a metal powder, an organic thiol, a radical-reactive compound and an addition-reactive compound.
Disclosed is a modified metal powder obtained by mixing a modifying substance of a kind with a metal particle under a milling condition where a new surface appears, and performing a mechanochemical reaction. It has been proposed to produce such thick film pastes. As described above, the modifying substance is bound to the surface of the metal particles by the mechanochemical reaction to improve the cohesiveness and dispersibility of the metal particles, thereby attempting to uniformly disperse the metal particles in the thick film paste.

Further, in Japanese Patent Laid-Open No. 9-278598, multi-twin metal ultrafine particles having a particle size of about 1 to 200 nm prepared by vacuum vapor deposition on the surface of an alkali halide crystal or the like are adsorbed to a metal surface such as alkanethiol. There is disclosed micelle-type metal fine particles in which molecular chains of organic substances are bonded to the surface of a metal surface in a micelle state by mixing with a solution of an organic substance having a.

Japanese Unexamined Patent Publication Nos. 8-259844 and 9
No. 278598, if the surface of metal particles is modified with an organic compound, the dispersibility of the metal particles in various matrices such as a binder or an aqueous solution can be improved, but stable dispersibility over a long period of time is expected. In addition, such modification with an organic compound did not significantly modify other physical properties such as electrical characteristics of the metal fine particles. Furthermore, even if the dispersibility in a matrix such as a resin is improved, for example,
When uniform and stable adhesion of a relatively small amount of substance is a problem, such as when coating the surface of a metal particle with a resin, satisfactory results can be obtained only by modifying the surface of the metal particle as described above. It was not there.

[0012]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel modified metal fine particle which solves the above problems in the prior art. Another object of the present invention is to provide coated metal fine particles having excellent uniformity and stability of the coating layer. Further, the present invention can exhibit a stable charge amount over a long period of time and has high reproducibility,
An object of the present invention is to provide an electrophotographic toner capable of forming a high quality image pattern. A further object of the present invention is to provide an electrophotographic toner useful for forming a conductor pattern such as circuit wiring.

[0013]

Means for Solving the Problems The present invention, which achieves the above-mentioned various objects, comprises a polymer comprising a metallic core particle and a polymer coating layer for coating the outer surface thereof, the polymer constituting the polymer coating layer. The coated metal fine particles are characterized in that the compound is chemically bonded to the surface of the metal core particles.

The present invention is further obtained by treating the metal core particles with a mercapto compound and mixing the treated metal core particles with the polymer or a monomer or oligomer thereof. It shows the coated metal fine particles described.

The present invention, which achieves the above-mentioned various objects, is also an electrophotographic toner comprising the coated metal fine particles according to the present invention.

The present invention further uses the above-mentioned electrophotographic toner according to the present invention, and after the electrophotographic toner is adhered in a predetermined pattern on the surface of a substrate by electrophotographic development, it is heat-treated, By removing the polymer compound component contained in the coated metal particles constituting the toner,
1 shows a method for forming a metal pattern, which comprises forming a metal pattern on the surface of a base material.

The present invention also shows a method for forming a metal pattern, wherein the base material is a ceramic green sheet, and the heat treatment is performed when the green sheet is heated and sintered.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments. The polymer-coated metal fine particles according to the present invention,
It is characterized by comprising a metal core particle and a polymer coating layer coating the outer surface thereof, and the polymer constituting the polymer coating layer is chemically bonded to the surface of the metal core particle. It is a thing.

Therefore, the polymer-coated metal fine particles according to the present invention have a high affinity with an organic solvent or resin and are easily dispersed, and by controlling the amount of the coated polymer, electrical resistance such as electric resistance can be improved. It is possible to control the mechanical properties, and because the coating polymer is chemically bonded to the metallic core particles, it has the mechanical strength that can withstand the treatment such as severe dispersion. It can be usefully used in all fields.

The metal core particles used in producing the polymer-coated metal fine particles of the present invention are not particularly limited, and examples thereof include gold, platinum, palladium,
Noble metals such as silver, ruthenium, rhodium, osmium, and iridium, and noble metal alloys containing 50% or more of these noble metals, iron, nickel, cobalt, copper, zinc, lead, aluminum, titanium, vanadium, chromium, manganese,
Zirconium, molybdenum, indium, antimony,
Examples include base metals such as tungsten, and alloys of these noble metals with base metals.

As will be described later, when the polymer-coated metal fine particles according to the present invention are used as an electrophotographic toner to form a conductor pattern such as circuit wiring, the metal fine particles include copper and nickel. , Gold, silver, platinum, palladium, ruthenium, molybdenum, tungsten, and the like, it is desirable to use a substance that exhibits good electric conductivity in the metal state. Of these, copper is particularly easy to oxidize and reduce, and as will be described later. It is desirable because it has good reactivity (complex formation) with other mercapto compounds and it is easy to finally chemically bond to a polymer.

When a one-component toner is used, it is preferable to use a metal exhibiting ferromagnetism such as iron, nickel and cobalt, or an alloy of these metals.

The particle size of such metal core particles is not particularly limited because it depends on the intended use of the polymer-coated metal fine particles to be finally obtained, but is not particularly limited. It is desirable that the particle size is 0.1 to 500 μm, more preferably about 1 to 50 μm. Further, each particle is uniform and has a sharp particle size distribution, specifically, for example, the value of number average particle diameter / volume average particle diameter is 1 to
It is desirable to have a characteristic such as 3.

The number of metal core particles is usually one per coated metal fine particle finally obtained, but a plurality of metal core particles can be used if necessary. In such an embodiment in which a plurality of core particles are used for each final particle, for example, before or during the coating treatment of the core particles with a polymer compound as described later, or during the treatment, the fine particles are appropriately sized. It may be carried out under the condition that the aggregated particles are treated with a polymer compound as it is.

Further, such a metallic core particle is subjected to a treatment for removing the surface oxide layer, if necessary, prior to the treatment with a mercapto compound or the like as described later, so that a chemical bond or a complex formation of the mercapto compound is formed. It can be in a state where it easily occurs.

In order to form a coating layer by chemically bonding a polymer compound to the surface of such metal core particles, first, a compound that forms a complex with a metal, for example, a mercapto compound as described below is used. Then, a functional group or structure having reactivity or affinity with the polymer compound is introduced on the surface of the metal core particle, and the reactivity or affinity between the introduced functional group or structure and the polymer compound. By using
This polymer compound is bound to the surface of the metallic core particles. In addition to the mercapto compound, for example, various silane coupling agents, it is also possible to introduce a functional group capable of chemically bonding to a polymer compound, a structure on the surface of the metal core using a compound such as a titanate coupling agent. is there.

The mercapto compound that can be used in the present invention has at least one thiol group capable of forming a chemical bond (complex formation) with the surface of the metallic core particles, and is reactive with a polymer compound as described below. Or a compound having a functional group or structure having affinity, particularly a polyfunctional mercapto compound, which is not particularly limited, and examples thereof include 1,6-dimethylmercaptohexane, dimercaptodiethyl ether, and 1,5. -Or 2,7-dimercaptonaphthalene, 2,2-dimercaptodiethyl sulfide, 2-dibutylamino-4,6-
Dimercapto-S-triazine, 2-phenylamino-
4,6-dimercapto-S-triazine, 2-anilino-4,6-dimercapto-S-triazine, 2-phenoxy-4,6-dimercapto-S-triazine, 2-diphenylamino-4,6-dimercapto-S. -Triazine, 2-benzylamino-4,6-dimercapto-S-
Triazine, 2-octylamino-4,6-dimercapto-S-triazine, 2-allylamino-4,6-dimercapto-S-triazine, 2-cyclohexylamino-4,6-dimercapto-S-triazine, 2-morpholino- 4,6-dimercapto-S-triazine, 2-t
-Butylphenylamino-4,6-dimercapto-S-
Triazine, 2- (p-methylamino) anilino-4,
6-dimercapto-S-triazine, 2-octadecylamino-4,6-dimercapto-S-triazine, 2-
Phenylethylamino-4,6-dimercapto-S-triazine, 2-phenylbenzylamino-4,6-dimercapto-S-triazine, 2-naphthoxy-4,6-
Dimercapto-S-triazine, 2-methoxy-4,6
-Dimercapto-S-triazine, 2-thioglycol-4,6-dimercapto-S-triazine, 2,4,6
-Trimercapto-s-triazine, 1,4-dimercapto-2,3-butanediol, 2,5-dimercapto-1,3,5-thiadiazole, 3,4-dimercaptotoluene, or other polyvalent mercapto compounds or these Alkali metal salt or alkaline earth metal salt of 2,4-dicyclohexylamino-6-mercapto-S
-Triazine, 2,4-diphenoxy-6-mercapto-S-triazine, 2,4-diethoxy-6-mercapto-S-triazine, 2,4-diphenyl-6-mercapto-S-triazine, 2-anilino-4 -Diphenylamino-6-mercapto-S-triazine, 2-anilino-4-octadecylamino-6-mercapto-S-triazine, 2-anilino-4-phenoxy-6-mercapto-S-triazine, 2-anilino-4 Examples include monomercapto compounds such as naphthoxy-6-mercapto-S-triazine and 2-dibutylamino-4-naphthoxy-6-mercapto-S-triazine. Of these, a triazine-based compound having a substituted thiol group is preferable, and a triazine-based compound having two to three substituted thiol groups is particularly preferable.

When such a mercapto compound is used, the amount added to the metallic core particles is 0.0001 to 20 parts by weight, preferably 0.001 to 10 parts by weight, based on 100 parts by weight of the metallic core particles. It is a department.

The reaction between the metallic core particles and the mercapto compound is carried out, for example, by dispersing the metallic core particles in a solution containing a predetermined amount of the above-mentioned mercapto compound and chemically bonding (complexing) the mercapto compound on the surface of the fine metal particles. Formation), the mixture is stirred and mixed for a predetermined time.

As a method for coating the metal core fine particles treated with the mercapto compound with the polymer compound, the reactivity with the functional group of the mercapto compound bonded to the surface of the metal core fine particles is utilized. And a method of utilizing the affinity with the mercapto compound.
The coating treatment with the polymer compound is performed, for example, by dispersing the metal fine particles treated with the mercapto compound as described above in a solution containing a substance having reactivity or affinity with the mercapto compound, and utilizing the reaction or the affinity. It is carried out by binding and depositing a polymer compound on the surface of the metal core particles, and uniformly coating the metal core fine particles with the polymer compound.

The most efficient method is to coat the polymer compound by chemically bonding it by utilizing the reactivity with the functional group of the mercapto compound.

The polymer used to obtain the coated metal fine particles of the present invention includes a functional group or structure introduced on the surface of the metal core particle as a result of treating the metal core particle with a mercapto compound or the like as described above. , Must have reactivity or affinity. As the functional group or structure, for example, in the case of using a polyvalent mercapto compound, a thiol group mainly located at a position different from the thiol group involved in the chemical bond with the metal core particles is mainly used. However, other substituents, functional groups, and atomic groups can also be targeted. When a monomercapto compound is used, the substituents other than the thiol group possessed by the compound, functional groups and atomic groups are targeted.

[0033] For example, in embodiments having a thiol group as a functional group introduced into the processing result metallic core particle surface a metal core particle mercapto compounds, for example, a thiol group and an epoxy group, the oxazolidinedione phosphorus group Ring-opening addition reaction, substitution reaction of thiol group with halogen group, crosslinking reaction for unsaturated bond of thiol group, bonding reaction of thiol group to radical generated by hydrogen abstraction reaction from ethylene group by peroxide, and thiol group Since it is possible to use an esterification reaction with a carboxyl group for chemical bonding between the polymer compound and the metallic core particles, the polymer compound that can be used is specifically, for example, one in the molecule. polymers having the above epoxy groups or oxazolidinedione phosphate group; vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, Polymers such as vinylidene chloride, chlorinated polyolefins, halogen group-containing polymers such as poly-4-fluoroethylene; homopolymers of vinyl acetate, ethylene, propylene, styrene, butadiene, isoprene, (meth) acrylonitrile, (meth) acrylic acid ester, etc. Polymer or copolymer; rubber such as fluororubber, chlorinated rubber, chloroprene rubber, epicrylhydrin rubber, polybutadiene, styrene / butadiene copolymer rubber, styrene / isoprene copolymer rubber, acrylonitrile / butadiene copolymer rubber, isoprene rubber, natural rubber Examples thereof include elastomers, other acrylic resins, terephthalic acid resins and unsaturated polyesters.

Further, if a polymer compound chemically bonded to the metallic core particles can be finally formed, a monomer, an oligomer or the like can be used during the reaction.

When the metal core particles treated with the mercapto compound or the like as described above are reacted with the polymer having reactivity with the functional group introduced on the surface of the metal core particles by such treatment, For the purpose of accelerating the reaction, it is possible to add heating or a reaction accelerator.

As the reaction accelerator, when the functional group is a thiol group, MgO, CaO, BaO, ZnO, C
An acid acceptor such as aCO ₃ and BaCO ₃ , a polyoxyethylene, an amine, a quaternary ammonium salt, a benzothiazole sulfide, a sulfinamide, a benzoyl peroxide, and a peroxide such as cumene peroxide can be appropriately used.

In the coated metal fine particles according to the present invention, the thickness of the coating layer made of the polymer compound chemically bound to the metallic core particles in this manner is not particularly limited. 0.1 to 50 μm, more preferably 0.3 to 30 μm. The electric resistance can be controlled by controlling the thickness of the coating layer, that is, the amount of the polymer compound.

As described above, the coated metal fine particles according to the present invention have a high affinity for various media and can be easily dispersed, the electric resistance of the metal can be controlled, and the mechanical strength and the like can be controlled. Since it has excellent physical properties, it can be usefully used in various fields. For example, semiconductor integrated circuits, electrodes formed on wiring boards, conductor patterns such as wiring, or metal pattern patterns formed on the surface of decorative plates, etc. Can be particularly preferably used as toner particles in the case of forming by applying an electrophotographic method.

The coated metal fine particles prepared as described above can be used as such toner particles as they are, but if necessary, coated with additives such as a charge control agent, a fluidizing agent and the like. It is possible to add it externally or internally to the polymer layer.

Examples of the charge control agent include nigrosine, monoazo dye, zinc, hexadecyl succinate,
Alkyl ester or alkyl amide of naphthoic acid,
Examples include nitrohumic acid, N, N-tetramethyldiamine benzophenone, N, N-tetramethylbenzidine, triazine, and salicylic acid metal complex.

Examples of the fluidizing agent include inorganic fine particles such as colloidal silica, hydrophobic silica, hydrophobic titania, hydrophobic zirconia, and talc, and organic fine particles such as polystyrene beads and (meth) acrylic resin beads. Can be used.

Depending on the case, various known colorants may be further added.

Further, as a substrate on which a desired pattern is formed by toner, a ceramic green sheet, a sintered ceramic sheet, or the like is used as described later,
In the embodiment in which the organic component (polymer compound) contained in the toner is removed by further heating after fixing the toner, in the case where the metal component (metal core particle) of the toner is adhered to the ceramics after such organic component removal. from the viewpoint of enhancing the gender, the toner, if necessary, PbO-SiO ₂ -
_{B 2 O 3, PbO-SiO} 2 -Al 2 O 3 -ZnOP
It is also possible to have arranged a glass component such as _{bO-ZnO-B 2 O 3} .

When used as such a toner, the surface resistance value is preferably about 10 ¹¹ to 10 ¹³ Ω / □, though not particularly limited thereto.

The method for forming a metal pattern using the electrophotographic toner according to the present invention is carried out through the steps of exposure, development and transfer, similarly to the usual electrophotographic method. That is, the electrophotographic photosensitive layer on the photosensitive plate is charged, the original plate having a desired pattern is irradiated and exposed to form this optical image (electrostatic latent image) on the photosensitive layer by electrostatic charging, and electrophotographic development is performed. By the method, toner is attached to the optical image portion to form (develop) a visible image of the toner on the photosensitive layer. After that, the substrate is brought into close contact with the photosensitive plate having the visible image formed on the surface thereof and heated, thereby transferring and fixing the toner to the substrate.

The fixed image of the predetermined pattern fixed on the substrate in this manner shows conductivity or metallic luster as it is, and the substrate is made of, for example, a resin material having poor heat resistance. In this case, the treatment may be completed as it is, but in order to form a metal layer which is more stably fixed on the substrate and exhibits excellent conductivity, the heat treatment is further applied to the coated metal fine particles constituting the toner. It is desirable to decompose or burn off the polymer compound component contained in and to perform a process of fusing the metal fine particles together. The temperature in such heat treatment cannot be specified unconditionally because it depends on the type of metal species used for the coated metal fine particles, the type of substrate used, and the like. , Ni, Ag
, Etc., a temperature of about 800 to 900 ° C.,
When Au, Pt, Pd, Ru, Mo, W or the like is used, the temperature is about 1500 to 1600 ° C.

In the metal pattern forming method of the present invention, a ceramic green sheet, that is, an unsintered ceramic sheet can be used as the substrate.

The ceramic green sheet is made by mixing fine ceramic powder with a polymer binder and molding it into a sheet, and is fired by heat treatment.
Sintered into a hard ceramic sheet.
Although the constituent material of the ceramic green sheet is not particularly limited, for example, alumina, silica,
Inorganic powders made of oxides or complex oxides such as zirconia, mullite, forsterite, cordierite, amorphous substances such as glass, nitrides such as aluminum nitride and silicon nitride, metals such as stainless steel and stellite, or alloys, or the like. Inorganic mixed powder is used as the main antibiotic agent, and (meth) acrylic resin, butyral resin, cellulose resin, polyvinyl alcohol resin, urethane resin,
It is formed by blending a binder composed of a styrene-maleic acid copolymer resin, wax or the like alone or in a mixture.

The method for producing the green sheet is not particularly limited, and for example, a slurry obtained by uniformly mixing the above-mentioned inorganic powder and binder with a solvent by a ball mill or the like is formed into a sheet by extrusion molding or the like. Alternatively, it can be obtained by casting on a polymer film, etc. and then drying it. At this time, if necessary, a sintering aid, a deflocculant, a plasticizer, a lubricant, an antifoaming agent, etc. are added. It is also possible to do so.

When such a ceramic green sheet is used as a substrate, the toner according to the present invention is fixed to the substrate in a predetermined pattern by the electrophotographic method as described above, and then the substrate, that is, the ceramic green sheet is fixed. At the time of heating and sintering, at the same time, the organic component (polymer compound) contained in the fixed toner is decomposed or burned and removed to form a desired metal pattern or conductor pattern.

When, for example, gold, copper, palladium / gold, etc. are used as the metal core particles of the coated metal fine particles to be the toner according to the present invention, a metal pattern having an extremely low conductor resistance can be obtained. However, in this case, using a combination of ceramic green sheets having a relatively low sintering temperature as a substrate prevents deformation of a desired pattern due to excessive melting of metal during sintering. Desired in.

Examples of such low temperature sinterable ceramics include, but are not limited to, glass ceramics composed of alumina and borosilicate crystallized glass, BaSn (BO ₃ ) _{2 and the} like. is not.

In the method for forming a metal pattern of the present invention, the substrate is not limited to such a ceramic green sheet, and for example, a sintered ceramic sheet,
Various resin substrates and various other substrates can be used.

The method for forming a metal pattern of the present invention can be used for various purposes. For example, conductor formation and firing in integrated circuit production by the ceramic lamination method using the above-mentioned ceramic green sheet as a substrate. Electronic component manufacturing fields such as conductor formation in the production of integrated circuits using bonded ceramic sheets, conductor formation in the production of various IC or LSI packages, formation of electrodes or wiring patterns on the surface of various elements, or formation of metal patterns on various substrates It can be preferably used in the field of manufacturing ornaments such as.

[0055]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the following description, the amounts (parts) of each component are all parts by weight.

Example 1 100 parts of copper particles having a volume average particle size of 6 μm were placed in an aqueous solution consisting of 50 parts of a 1% sulfuric acid aqueous solution and 100 parts of deionized water and treated for 30 minutes with uniform stirring.

Next, the copper particles were allowed to settle to remove the sulfuric acid aqueous solution, the copper particles were thoroughly washed with water, and finally washed with methanol.

300 parts of a 1% methanol solution of 2,4,6-trimercapto-s-triazine was added to the copper particles, and the reaction was carried out at room temperature (25 ° C. ± 5 ° C.) for 3 hours with uniform stirring.

Unreacted 2,4,6-trimercapto-s
The triazine was washed off with methanol and finally with toluene. The oxazoline group-containing acrylic polymer (isopropenyl oxazoline / methyl maythacrylate / n-butyl acrylate = 20/60/20, Mw = 15.0) was added to the copper particles treated with the mercapto compound.
40 parts of a 25% toluene solution of 00) and 150 parts of toluene were added, and the reaction was carried out at room temperature for 5 hours with uniform stirring.

Unreacted polymer was removed by washing with toluene, and finally with methanol, and then dried with a hot air dryer at 50 ° C. for 24 hours to obtain copper particles (1).

The polymer coating amount of the obtained copper particles (1) was measured by Shimadzu Thermal Analysis System DTA-50 (high sensitivity TG) (manufactured by Shimadzu Corporation), and the polymer coating amount was 5.9%.
Met.

The average particle diameter of the copper particles (1) was measured by Coulter Multisizer Ii (manufactured by Coulter Co.), and the volume average particle diameter was 6,8 μm.

Example 2 To 100 parts of copper particles coated with the polymer obtained in the same manner as in Example 1 was added 15 parts of methanol in which 3 parts of the charge control agent Kayacharge N-1 (manufactured by Nippon Kayaku) was dissolved. Then, while kneading in a mortar, methanol was evaporated to uniformly fix the charge control agent to the copper particles.

The copper particles (2) thus obtained were placed in a grounded metal container so that the surface was smooth, and were forcibly charged by corona charge, and the change in surface potential was measured for 5 minutes. The rate was 94%, which was very good.

20 parts of the silicon-coated ferrite carrier was shake-mixed with 1 part of the copper particles (2), and the charge amount was measured by the blow-off method. The result was -8 μc / g.

Using the copper particles (2) as a toner, an image was formed on a ceramic green sheet of A4 size and a thickness of 25 μm by a commercially available copying machine.

This ceramic green sheet was heated to 900 ° C. at 0.5 ° C./minute in a reducing atmosphere, and then heated to 2 ° C. at the same temperature.
As a result of holding for a time and firing / sintering, an image containing copper as a main component was firmly fixed on the sintered ceramic sheet.

Then, electrical continuity was confirmed at arbitrary portions of the image which were continuously connected.

Comparative Example 1 In Example 1, 2,4,6-trimercapto-s-
Copper particles (C1) were obtained in the same manner as in Example 1 except that the treatment with triazine was not performed.

The obtained copper particles (C1) were evaluated in the same manner as in Example 1. As a result, the SEM photographs showed almost no copper particles coated with the polymer.

The coating amount of the polymer was 0.3%, and the charge retention rate was measured in the same manner as in Example 2.
The retention rate was 4%.

Comparative Example 2 Copper particles (C2) were prepared in the same manner as in Example 1 except that the oxazoline group-containing acrylic polymer of Example 1 was not added.
Got

The obtained copper particles (C2) were evaluated in the same manner as in Example 1. As a result, the SEM photographs showed almost no copper particles coated with the polymer.

The coating amount of the polymer was 0.1%, and the charge retention rate was measured in the same manner as in Example 2.
The retention rate was 1%.

[0075]

As described above, the coated metal fine particles according to the present invention have a high affinity with an organic solvent or resin and can be easily dispersed, and the electric resistance can be controlled by controlling the amount of the coating polymer. It is possible to control electrical properties such as, and because the coating polymer is chemically bonded to the metallic core particles,
It has mechanical strength that can withstand treatments such as harsh dispersion, and can be usefully used in all fields where metal fine particles are used. In particular, an electrophotographic method for forming a metal pattern or a conductor pattern is used. The toner can be preferably used as a toner in the case of applying.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-259844 (JP, A) JP-A-4-237062 (JP, A) JP-A-3-163172 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 9/08 H05K 3/00 C09C 3/00

Claims (5)

(57) [Claims] 1. A metal core particle and a polymer coating layer coating the outer surface of the core particle are provided, and the polymer compound constituting the polymer coating layer is chemically bonded to the surface of the metal core particle. Coated metal fine particles, wherein the metal core particles are treated with a mercapto compound,
Mixing the metal core particles with the polymer compound
A coated metal fine particle obtained by. 2. The bond comprises a thiol group and an epoxy group.
Ring-opening addition reaction with oxazoline group or thiol group
For substitution reaction with rogen group and unsaturated bond of thiol group
Cross-linking reaction, hydrogenation from ethylene group by peroxide
Of the thiol group to the radical generated by the scavenging reaction
The binding reaction and the reaction between the thiol group and the carboxyl group
At least one selected from the group consisting of stealization reactions
It is formed by the following.
Coated metal fine particles. 3. The polymer compound has one or more molecules in the molecule.
Polymers containing epoxy or oxazoline groups
The cover according to claim 1 or 2, characterized in that
Covered metal particles. 4. The device according to claim 1, wherein
After the electrophotographic toner is adhered in a predetermined pattern on the surface of the base material by electrophotographic development using the electrophotographic toner using the fine particles of the metal covering , the heat treatment is performed to coat the metal forming the toner. A method for forming a metal pattern, which comprises forming a metal pattern on the surface of a base material by removing a polymer compound component contained in fine particles. 5. The method for forming a metal pattern according to claim 4, wherein the base material is a ceramic green sheet, and the heat treatment is performed when the green sheet is heated and sintered.