JP2002244342A - Electrostatic charge image developer and electrically conductive wiring pattern forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge image developer with which a high density and high precision wiring pattern is printed by an electrostatic recording system or an electrophotographic method and a high accurate and low resistant electrically conductive pattern free from voids, defects, etc., is formed, and to provide an electrically conductive wiring pattern forming method using the developer. SOLUTION: The electrostatic charge image developer comprises a carrier and capsulated particles for electrostatic charge image developing having at least fine metal particles and insulating resin films which encapsulate the fine metal particles. The absolute value of the quantity of electric charges of the capsulated particles measured with a device for measuring the distribution of the quantity of electric charges is |1.8-3.8| (femtoC/10 μm), the standard deviation of the quantity of electric charges is <=2.5 and capsulated particles charged to the same polarity are contained by >=95 number %.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel capsule in which a fine powder of a metal such as copper, silver, gold, platinum or tungsten is encapsulated with an insulating resin, which is preferably used for printing a wiring pattern. And a method for forming a conductive wiring pattern using the same. In particular,
Caps for electrostatic charge image development by forming a wiring pattern by dry or wet electrostatic recording method or electrophotography and then sintering to form a conductive wiring pattern. The present invention relates to an electrostatic image developer comprising activated particles and a carrier.

[0002]

2. Description of the Related Art Conductive wiring patterns used for electrodes, sensors, antennas, and the like for electric circuits and capacitors for mounting ICs and LSIs are formed on an insulating inorganic substrate by electrostatic recording or electrophotography. In some cases,
Resin particles obtained by coating metal fine particles with an insulating resin are used.

[0003] The resin particles containing the fine metal particles have excellent developing characteristics that enable high-density and high-precision wiring patterns to be printed by electrostatic recording or electrophotography. In order to obtain a conductive circuit with low resistance by sintering, it is developed in a state in which resin particles in which metal fine particles are coated with an insulating resin are packed in a close-packed state. A step of completely burning and removing is performed, and in that case, it is required that metal fine particles contained in the resin be closest packed.

In order to satisfy these characteristics, (a) the metal fine particle surface is uniformly encapsulated with a thin resin film, and (b) the encapsulated particles have a sufficient charge amount,
Further, the charge amount distribution is sharp and uniformly charged, (c) the particle size distribution of the encapsulated particles is sharp, the shape of the particles is infinitely spherical, and the particle size is small, etc. is necessary.

[0005] However, conventional resin particles obtained by coating metal fine particles for forming a conductive wiring pattern with an insulating resin cannot hold a sufficient charge because the metal portion is exposed. Resin particles having poor charging characteristics. Also, even if the metal part is completely covered and the charge amount can be maintained, on the contrary, the insulating resin coating film is too thick and the resin is completely burned by sintering and disappears Even after this, the space occupied by the resin could not be filled with the molten metal fine particles, which often resulted in voids in the conductive circuit, resulting in defective conductive wiring patterns. . Furthermore, in the prior art, although the total charge amount of the resin particles for forming a conductive pattern as a whole is mentioned, it is necessary to faithfully and electrostatically develop an electrostatic latent image in electrophotography. No consideration is given to conditions such as an appropriate charge amount, a sharp charge amount distribution, and a low content ratio of oppositely charged particles.

As described above, conventional resin particles obtained by coating metal fine particles for forming a conductive wiring pattern with an insulating resin are:
Sufficient studies have not been made on the characteristics as an electrostatic charge image developer for printing a high-precision wiring pattern, and a device for obtaining a low-resistance conductive path by close packing.

For example, Japanese Patent Application Laid-Open No. H11-298119,
Japanese Patent Application Laid-Open No. H11-265089 discloses a method in which a resin and metal particles are kneaded, and then a particle in which the metal particles are dispersed in the resin is produced by a pulverization method. In the resin-coated metal particles obtained by these pulverization methods, the metal particles are exposed on the particle surface, the charge level is low because the charge leaks, and the metal content cannot be increased because the metal surface is exposed. . Therefore, when developed by the electrophotographic method, fogging is large, and a fine and low-resistance conductive pattern cannot be stably formed.

Further, Japanese Patent Application Laid-Open No. H11-193402,
JP-A-11-194526 discloses a method for producing resin particles in which metal fine particles are coated with an insulating resin by directly polymerizing a monomer on the surface of the metal particles. In the manufacturing method disclosed by these, it is difficult to uniformly coat the particle surface with a resin film having a uniform thickness, and it is easy to generate coarse particles due to aggregation of the particles, and as a result, the particle size distribution Tends to be wide.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide an electrostatic charge developer having excellent development characteristics capable of printing a high-density and high-precision wiring pattern by an electrostatic recording method or an electrophotographic method and a method of forming a conductive wiring pattern using the same. . Another object of the present invention is to provide an electrostatic charge image including encapsulated particles for electrostatic charge development coated with a fine metal powder by an insulating resin that enables high-density filling when a wiring pattern is printed. An object of the present invention is to provide a developer and a method for forming a conductive wiring pattern using the same. Further, another object of the present invention is to sinter the printed wiring pattern and completely burn the insulating resin, thereby filling the metal particles in a close-packed manner, and having high accuracy and low voids and defects. An object of the present invention is to provide an electrostatic image developer containing an encapsulated particle for electrostatic charge development capable of forming a conductive pattern of resistance, and a method of forming a conductive wiring pattern using the same.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have developed an electrostatic image development having at least metal fine particles and an insulating resin film encapsulating the metal fine particles. A developer comprising encapsulated particles for use and a carrier, wherein the absolute value of the charge amount of the encapsulated particles measured by a charge amount distribution measuring device is | 1.8 to 3.
8 | (femtoC / 10 μm), the standard deviation of the charge amount distribution is 2.5 or less, and 95% by number or more of encapsulated particles charged to the same polarity are contained. The agent is provided.

Further, the present invention provides a method for printing a wiring pattern on an insulating inorganic substrate using an electrostatic image developer, and thereafter,
In the method of forming a conductive wiring pattern of a metal on the insulating inorganic substrate by sintering the wiring pattern, the developer has at least metal fine particles and a coating of an insulating resin that encapsulates the metal fine particles. A developer composed of encapsulated particles for electrostatic image development and a carrier, wherein the absolute value of the charge amount of the encapsulated particles measured by a charge amount distribution measuring device is | 1.8 to 3.8 | (femt
oC / 10 μm) and the standard deviation of the charge amount distribution is 2.
5 or less, and the number of encapsulated particles charged to the same polarity is 95 or less.
An object of the present invention is to provide a method for forming a conductive wiring pattern, wherein the conductive wiring pattern is contained in an amount of at least several percent.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As described in the prior art, in order to develop a high-definition wiring pattern by electrophotography, three elements, that is, an appropriate charge amount, a sharp charge amount distribution, and a small number of oppositely charged particles are essential. The charge characteristics of such a developer can be measured by a charge amount distribution measuring device. In the present invention, the charge amount of the encapsulated particles, the standard deviation of the charge amount distribution, and the content ratio of the oppositely charged particles are values measured by an E-spurt analyzer (manufactured by Hosokawa Micron Corporation) which is a charge amount distribution measuring device.

The E-Spurt analyzer vibrates the toner particles by causing the toner particles to fall between two electrodes having opposite acoustic vibration polarities, and also moves the toner particles to the electrodes by the electric field action of the electrodes. At this time, the particle frequency and the charge amount of each particle are calculated by simultaneously measuring the frequency and the moving distance of the toner by the laser Doppler method. According to the present apparatus, it is possible to measure the charge amount distribution of the particles in a specific particle diameter range and easily measure the total charge of the particles. E
-For details of the principle of measuring the amount of toner charge by a spurt analyzer, see "Japan Hardcopy '
90 papers, pages 101-104, by Hosokawa Micron Corporation.

The charged amount of the encapsulated particles of the present invention has an absolute value of | 1.8 to 3.8 | (femtoC / 10 μm).
m). The value of the charge amount is a value calculated by an E-spurt analyzer, and is a converted value when the average particle size of the encapsulated particles whose charge amount is measured is 10 μm. In order to print wiring patterns with higher accuracy,
The absolute value of the charge amount is | 1.8 to 3.5 | (femtoC /
10 μm), particularly | 2.0-3.
0 | (femtoC / 10 μm). The absolute value of the charge amount is | 1.8 | (femtoC / 10
If the average particle diameter is smaller than (μm), the encapsulated particles are powders having a relatively large specific gravity and cannot be retained in the carrier, causing a scattering phenomenon, fogging and the like, which is liable to cause contamination of the non-image area. If there is a lot of fog, a short circuit occurs in the conductive pattern, and it cannot be used as a conductive pattern. On the other hand, if the absolute value of the charge amount is higher than | 3.5 | (femtoC / 10 μm), the transfer amount to the insulative inorganic substrate as the transfer material decreases, and a conductive line having a sufficient line width or thickness is formed. It cannot be secured.

The polarity at the time of charging of the encapsulated particles is as follows.
Either positive charge or negative charge may be used. However, since the insulating resin used in the present invention is preferably a resin containing an acidic group, it is preferable to use encapsulated particles having negative charge.

The standard deviation of the charge distribution in the encapsulated particles of the present invention is 2.5 or less, more preferably 2.0 or less. If the standard deviation is larger than 2.5, the distribution of the charge amount becomes broad, the development is not performed uniformly, and unevenness occurs in the printed image. Further, selective development of the encapsulated particles occurs, and the durability of the developer deteriorates. Also,
In the encapsulated particles of the present invention, the content of particles charged to the same polarity is 95% by number or more. It is more preferably at least 97% by number. This means that, for example, when the encapsulated particles of the present invention are negatively chargeable particles, the number of negatively chargeable particles is 95% by number or more of all particles,
This means that the number of positively charged particles that are oppositely charged is 5% by number or less. If the number of the oppositely charged encapsulated particles is 5% by number or more, scattering is likely to occur, and fogging tends to occur.

The encapsulated particles for developing an electrostatic image of the present invention are encapsulated particles having fine metal particles and a coating of an insulating resin for encapsulating the fine metal particles, and have an average circularity of 0.
It is preferable that the encapsulated particles have a shape close to 97 true spheres (spherical or substantially spherical). When the average circularity is 0.97 or more, the fluidity of the encapsulated particles is improved. Further, because of the shape close to a true sphere, for example, resin particles having an acidic group, resin particles containing a charge control agent in a resin having an acidic group, or a normal toner used for electrostatic image developing toner Inorganic compounds such as silica and alumina can be uniformly attached or fixed to the surface of the encapsulated particles. As a result, it is possible to obtain an electrostatic image developer having a good charge rise and excellent triboelectric characteristics. In addition, in order to show good fluidity, the two-component developer using the encapsulated particles for developing an electrostatic image of the present invention is used when the replenishment of the encapsulated particles into the developing device is repeated in long-time printing. However, it is not instantaneously mixed with the carrier and does not impair the quality of the printed image.

The encapsulated particles for electrostatic image development in which metal fine particles are coated with an insulating resin have a high specific gravity, and a large force is applied to the contact surface between the charged particles when the particles are filled in a developing device. Therefore, poor fluidity or poor charging due to poor fluidity is likely to occur.However, the encapsulated particles for electrostatic image development of the present invention have a uniform particle size, and have a shape close to a true sphere that is easily moved by external force. Therefore, good fluidity and charging characteristics can be exhibited.

Furthermore, since the encapsulated particles for developing an electrostatic image of the present invention have a shape close to a true sphere, when the encapsulated particles are developed on an insulating inorganic substrate, the encapsulated particles are closely packed with each other. A pattern can be formed. By doing so, when the printed wiring pattern is sintered and the insulating resin is completely burned, the metal fine particles contained in the encapsulated particles are packed closest and the voids and defects are reduced. It is possible to form a conductive pattern with no high precision and low resistance.

The circularity of the encapsulated particles is a value defined by (perimeter of a circle having the same area as the projected area of the particles) / (perimeter of the projected image of the particles), and the average circularity is the circularity of each particle. It is an average value. The average circularity, and circularity, is the S of the encapsulated particles.
It can also be determined by taking an EM (scanning electron microscope) photograph, measuring and calculating the same, but in the present invention, the flow particle image analyzer FPIP-1000 manufactured by Toa Medical Electronics Co., Ltd. is used. The measured value was defined as the average circularity or circularity.

The average circularity of the encapsulated particles for developing an electrostatic image of the present invention is more preferably 0.98 or more.
As the average circularity is 0.98 or more and the shape is closer to a true sphere, the filling of the encapsulated particles in the wiring pattern becomes denser, and a smooth and dense conductive path can be formed after sintering.

The number of encapsulated particles having a circularity in the range of 0.98 to 1.00 is 80% by number or more, and the number of encapsulated particles in the circularity of 0.95 or less is 6% by number or less. It is preferred that

The volume average particle diameter of the encapsulated particles for developing an electrostatic image of the present invention is preferably in the range of 0.5 to 20 μm, more preferably 2 to 10 μm. In particular, it is preferable that the volume average particle diameter is in the range of 2 to 8 μm, since it is possible to develop a high-definition and dense wiring pattern.

As for the particle size distribution, (50% volume average particle size / 50% number average particle size) is 1.25 or less, more preferably 1.20 or less, further preferably 1.15 or less, And have a particle size distribution in which the square root (hereinafter abbreviated as GSD) of (84% volume particle size / 16% volume particle size) is 1.30 or less, more preferably 1.25 or less, and still more preferably 1.20 or less. Is necessary for developing good chargeability and forming a high-quality printed image without fog. By satisfying such a sharp particle size distribution,
Since the encapsulated particles can be arranged at a high density without gaps, it is advantageous for forming a conductive pattern having a low resistance value. The particle size distribution of the present invention was measured using Coulter Multisizer II.

Incidentally, the value of (50% volume average particle diameter / 50% number average particle diameter) becomes smaller when a large number of fine particles having a particle diameter smaller than the average particle diameter are present, resulting in a larger value. On the other hand, the value of (84% volume average particle size / 16% volume average particle size) becomes larger when a large number of coarse particles having a particle size larger than the average particle size exist, resulting in a larger value. In each case, the closer the value is to 1, the sharper the particle size distribution is. The closer the value is to 1, the closest packing of the encapsulated particles is performed during development.

The encapsulated particles for developing an electrostatic image of the present invention preferably have a structure in which one encapsulated particle contains a plurality of fine metal particles. When a plurality of metal fine particles having a small particle size compared to the particle size of the encapsulated particles are included in the encapsulated particles, when the wiring pattern printed by electrophotography or electrostatic recording is sintered Thus, a smoother and denser conductive path can be formed.

"Encapsulation" in the present invention means that the insulating resin has a structure in which the metal fine particles are completely covered. Therefore, the metal fine particles are not exposed on the surface of the encapsulated particles, and as a result, no electric charge leaks on the particle surface. As a result, the encapsulated particles for developing an electrostatic image of the present invention can have high charging performance, and a high-definition wiring pattern can be printed even when printing a large number of sheets. Whether the metal fine particles are not exposed on the surface of the encapsulated particles for electrostatic image development of the present invention can be easily determined by, for example, observing the cross section of the particles with an SEM (electron microscope). More specifically, the section obtained by embedding the encapsulated particles in a resin and cutting with a microtome is referred to as SE.
When observed with M, it can be confirmed that the metal fine particles are completely included in the particles and are not exposed on the surface of the encapsulated particles.

The volume average particle diameter of the metal fine particles is preferably 1/2 to 1/100 of the obtained encapsulated particles. More specifically, the smoothness of the conductive pattern,
In order to ensure denseness, the range is preferably 0.1 μm to 6 μm, and more preferably 0.5 to 4 μm.
The particle size of fine particles such as metal fine particles can be measured using a Microtrac Ultrafine Particle Analyzer, Coulter Multisizer, or the like.

Further, in the encapsulated particles for developing an electrostatic image of the present invention, the weight ratio of the insulating resin to the total weight of the encapsulated particles is preferably 20% or less.
If the amount of resin is large, when sintering the developed wiring pattern, a large space is created in the trace where the resin burns and disappears,
Small holes may be generated in the conduction path, or the conduction path may be lost. As a result, the resistance value of the conduction circuit increases or conduction failure occurs. In order to prevent small holes or breakage in the conduction path, the amount of resin must be 20 or less.
% By weight or less, particularly preferably 15% by weight or less.
% By weight or less.

The metal fine particles usable in the present invention include:
^Fine metal particles mainly composed of a metal having a specific electrical resistance at 20 ° C. of 1 × 10 ⁻⁴ Ω · cm or less are preferably used. Examples of metals include precious metals such as gold, platinum, palladium, silver, ruthenium, rhodium, osmium, and iridium, and precious metal alloys containing these precious metals in an amount of 50% by weight or more, nickel, cobalt, copper, zinc, lead, aluminum, Titanium,
Examples include base metals such as vanadium, chromium, manganese, zirconium, molybdenum, indium, antimony, and tungsten, and alloys of these noble metals and base metals.

Particularly preferred metals as metal fine particles for forming conductive wiring patterns for electronic circuits are copper, silver,
It is at least one metal selected from gold, nickel, tungsten, platinum, palladium, ruthenium, and molybdenum, but also has a specific electrical resistance of 9 × 10 ⁻⁶ Ω ·
Those containing a metal of cm or less as a main component are particularly preferable as metal fine particles for forming a conductive pattern. These metals may have oxidized surfaces. It is also possible to perform sintering of the wiring pattern under conditions in which the oxide is reduced, and a metal oxide can be used without any problem as a material for forming a conductive wiring pattern.

The shape of the metal fine particles is such that the ratio of the long axis average diameter / the short axis average diameter is 1.5 or less, more preferably 1.2 or less, and the average circularity is 0.95 or more, and more preferably 0.5 mm or less. 97 or more, most preferably 0.98 or more approximately spherical
It is preferably spherical. Needle-shaped metal particles,
Spindle-shaped or other irregular shaped particles may generate particles that are not sufficiently encapsulated, and even if encapsulated, the smoothness and denseness after sintering are impaired Therefore, it is not preferable.

In order to uniformly coat the metal fine particles with the insulating resin without exposing the metal fine particles to the surface of the encapsulated particles,
It is preferable to perform encapsulation after introducing a polar group on the surface of the metal fine particles. In particular, when using an acidic group-containing resin as the insulating resin, it is effective to easily wet the surface of the metal fine particles by treating the metal fine particles with a nitrogen-containing compound that causes an acid-base reaction with an acidic group. Yes,
Thereby, a uniform resin film can be formed without exposing the metal fine particles with a small amount of resin.

Suitable examples of the surface treatment agent for metal fine particles include, for example, a nitrogen-containing silane coupling agent, an aminosilane coupling agent,
β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane , Γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-aminopropyldimethoxymethylsilane and the like. As the aluminum coupling agent, γ-aminopropyltrimethoxyaluminum, γ-aminopropyltriethoxyaluminum,
γ-aminopropyldimethoxymethylaluminum and the like. Also, as a titanium coupling agent,
γ-aminopropyltrimethoxytitanium, γ-aminopropyltriethoxytitanium, γ-aminopropyldimethoxymethyltitanium and the like.

As a method of treating the surface of the metal fine particles with the above-mentioned surface treating agent, for example, a fixed ratio of water, isopropyl alcohol, and aminosilane coupling agent in a range of 60 to 90
Minutes, after hydrolyzing the aminosilane coupling agent, mixed with metal fine particles, immersed for 12 to 24 hours, to adsorb aminosilane on the metal fine particle surface,
Dehydration condensation may be performed at 120 ° C. for about 2 hours.

The insulating resin that can be used for producing the encapsulated particles for developing an electrostatic image of the present invention is a vinyl copolymer resin such as a polystyrene resin, a styrene acrylic resin, or a styrene butadiene resin. Further, a polyester resin, an epoxy resin, a butyral resin, a xylene resin, a coumarone indene resin, a polyurethane resin, and the like can be given. Among these, a non-water-soluble resin having a functional group that becomes hydrophilic by neutralization is used. In addition, a self-water-dispersible resin which becomes self-dispersible by neutralizing a part or all of the functional groups of the resin is preferably used.

In the insulating resin containing an acidic group, a part or all of the acidic group is neutralized by a base. By doing so, it is possible to form encapsulated particles that are stably dispersed in an aqueous medium (self-water dispersibility) without using an emulsifier or a dispersion stabilizer. Hereinafter, the insulating resin containing the acidic group having such characteristics is referred to as “self-water dispersible resin”. When such a self-water-dispersible resin is dispersed in an aqueous medium together with metal fine particles, a hydrophobic portion of the resin is adsorbed on the metal fine particles, and a hydrophilic portion is localized at an interface with the aqueous medium. Thereby, encapsulated particles in which metal fine particles are included in the particles can be generated. During the production of the encapsulated particles, the interfacial tension difference between the resin or the organic solvent solution of the resin and the aqueous medium is large, so that the capsule particles are simultaneously made spherical.

The encapsulated particles of the present invention have excellent charging performance because the hydrophilic groups of the self-water-dispersible resin are localized on the particle surface. In addition, since the encapsulation is carried out using only a self-water dispersible resin neutralized with a base without using an emulsifier or a dispersion stabilizer, they remain on the surface of the encapsulated particles and adversely affect the chargeability. Has no effect.

Examples of the functional group which can be made hydrophilic by neutralization include a carboxyl group, a phosphoric acid group, a sulfonic acid group and a sulfuric acid group. Among them, a resin containing a carboxyl group is preferable. More specifically, a styrene (meth) acrylic acid-based resin obtained by polymerizing a monomer having a carboxyl group and a polyester resin are preferable. Such a styrene (meth) acrylic resin containing an acidic group contains a styrene monomer as an essential component, and radically polymerizes a polymerizable monomer containing an acidic group and another polymerizable vinyl monomer. Can be obtained.

(A) Examples of the styrene monomer include styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, chlorostyrene and the like.

(B) Examples of the polymerizable monomers containing an acidic group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monobutyl itaconate, monobutyl maleate, and acid phosphonate. Oxyethyl methacrylate, acid phosphooxypropyl methacrylate, 3-chloro-2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl methacrylate and the like can be mentioned.

(C) Other polymerizable monomers include:
For example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-acrylate Octyl, decyl acrylate or dodecyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, alpha methyl methyl acrylate, methyl methacrylate, propyl methacrylate,
N-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate, dodecyl methacrylate, 2-chloroethyl methacrylate, methacrylic acid Phenyl,
Acrylic acid or methacrylic acid derivatives such as alpha-chloromethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone, N-vinyl pyrrole , N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone, and the like.

As a method for producing a copolymer of styrene- (meth) acrylate containing an acidic group, a usual polymerization method can be adopted, and a polymerization catalyst such as solution polymerization, suspension polymerization, bulk polymerization and the like can be used. A method in which a polymerization reaction is carried out in the presence of an organic solvent.

As the polymerization catalyst, for example, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-yl)
(Carbonitrile), benzoyl peroxide, dibutyl peroxide, butyl peroxybenzoate, and the like, and the amount used is 0.1 to 10.
0% by weight is preferred.

The above-mentioned styrene (meth) acrylic resin can be used as it is, but if necessary, a part of the resin may be crosslinked. By performing such cross-linking, the film of the encapsulated particles is not destroyed by friction or collision between the encapsulated particles or between the encapsulated particles and the carrier particles in the electrophotographic developing device.

As a method for crosslinking the insulating resin, it is preferable to encapsulate the metal fine particles and then react the functional group in the resin with a crosslinking agent. For example, when the functional group of the resin is a carboxyl group, an aminoplast resin, a compound having an average of two or more glycidyl groups per molecule as a crosslinking agent that reacts with the carboxyl group to crosslink the resin, 1,3-dioxolan-2
A compound having an average of two or more -on-4-yl groups in one molecule; a compound having an average of two or more carbodiimide groups in one molecule (for example, carbodilite; a carbodiimide group-containing cross-linking agent of Nisshinbo Co., Ltd.); oxazoline in one molecule Examples thereof include compounds having an average of two or more groups, and metal chelate compounds. When the functional group of the resin is a hydroxyl group, examples of the crosslinking agent that reacts with the hydroxyl group include aminoplast resins, polyisocyanate compounds, and blocked polyisocyanate resins.

As a method for introducing a carboxyl group which reacts with the crosslinking agent into the insulating resin, the above-mentioned component (B) may be copolymerized with the component (A) and, if necessary, with the component (C). In the case where the functional group is a hydroxyl group, the polymerizable monomer having a hydroxyl group as the functional group is used as the above (A), (B)
It can be easily produced by copolymerizing with the component and, if necessary, the component (C).

Examples of the polymerizable monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate,
-Hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, "Placcel F
Lactone compounds such as "M-2" and "Placcel FA-2" (manufactured by Daicel Chemical Industries, Ltd.)
Acrylic monomers; polyethylene glycol mono (meth) acrylate monomers, polypropylene glycol mono (meth) acrylate monomers, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, and the like.

A preferred example of crosslinking the insulating resin is a combination of a resin having a carboxyl group as a functional group and a compound having an average of two or more glycidyl groups in one molecule. Compounds having an average of two or more glycidyl groups in one molecule include, for example, bisphenol A
Glycidyl ethers of phenols such as epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, cresol novolac type, etc .; neopentyl glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, polypropylene dipropylene Glycidyl ether,
Glycidyl ethers of various glycols and polyols such as trimethylolpropane diglycidyl ether and sorbitol polyglycidyl ether; glycidyl esters such as diglycidyl adipate and diglycidyl phthalate; glycidyl groups such as glycidyl (meth) acrylate A vinyl copolymer obtained by copolymerizing a polymerizable monomer having: epoxidized polybutadiene;
Glycidylamine compounds such as diglycidylaniline, triglycidylparaaminophenol, triglycidylmethaminophenol, and tetraglycidylaminodiphenylmethane.

In the present invention, the reaction between the insulating resin and the crosslinking agent is preferably carried out in an aqueous medium, and therefore, the crosslinking reaction is carried out at a temperature lower than the boiling point of water. In particular, in order to avoid fusion between the encapsulated particles, it is preferable to carry out the reaction near the glass transition temperature of the insulating resin. As such a crosslinking agent capable of reacting with a carboxyl group under relatively low temperature conditions, a glycidylamine compound having a glycidyl group represented by the following general formulas (1) and (2) is preferable. General formula (1)

[0051]

Embedded image General formula (2)

[0052]

Embedded image (In the above general formulas (1) and (2), R ₁ and R ₂ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aromatic ring group which may have a substituent or an alicyclic group. , R ₃ represents an alkyl group having 1 to 4 carbon atoms.)

Examples of the crosslinking agent having the above structure include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylbenzylamine, N, N-diglycidyl-α-phenylethylamine, N, N, N ′, N′-tetraglycidylisophoronediamine, and the like.

The reaction ratio in the case where the insulating resin is reacted with the crosslinking agent is not particularly limited. For example, in the case where the functional group is a carboxyl group, the reaction ratio is 1.0 equivalent to the carboxyl group. Glycidyl group is 0.001-1.
It is preferable to use a compound having a glycidyl group in an amount in the range of 0 equivalents. When the amount of the glycidyl group is less than 0.001 equivalent relative to 1.0 equivalent of the carboxyl group, the polymerization or crosslinking becomes insufficient. Not preferred.

When a glycidylamine compound or other glycidyl group-containing compound is used as a crosslinking agent,
A known catalyst such as methylimidazole may be used, or a secondary monoamine such as dibutylamine may be added to a part of the glycidyl group to give the glycidyl group-containing compound an autocatalytic ability.

The acid value of the styrene (meth) acrylic resin is preferably from 10 to 150, more preferably from 30 to 100, even more preferably from 40 to 80. If the acid value is lower than 10, the desired charge amount cannot be obtained, and the dispersibility in an aqueous medium is reduced, which causes a problem in producing encapsulated particles. Further, when a cross-linking reaction is carried out using a carboxyl group in the insulating resin, it is not preferable because the molecular weight of the resin does not progress or the cross-link density decreases. On the other hand, if the acid value is higher than 150, the hygroscopicity of the encapsulated particles increases, which is not preferable.

The styrene (meth) acrylic resin used in the present invention preferably has a glass transition temperature of 50 ° C. or higher as measured by DSC (differential scanning calorimeter).
The temperature is more preferably in the range of not less than 110 ° C and not more than 110 ° C. When the glass transition temperature is lower than 50 ° C., the thermal stability of the obtained encapsulated particles tends to deteriorate, which is not preferable.

Before the crosslinking reaction of the styrene (meth) acrylic resin, the weight average molecular weight of the THF-soluble component (measured by gel permeation chromatography in terms of polystyrene) is preferably in the range of 5,000 to 300,000. More preferably, the range is from 000 to 150,000. If the weight average molecular weight is less than 5,000, the amount of resin dissolved in the aqueous medium after dispersion in the aqueous medium increases,
This is not preferable because the yield of encapsulated particles tends to decrease, and the crosslinking reaction does not proceed sufficiently and the resin strength tends to be insufficient. In addition, the weight average molecular weight is 300,
If it is larger than 000, it is not preferable because it tends to be difficult to disperse in an aqueous medium.

The styrene (meth) acrylic resin may be a system in which resins having different weight average molecular weights are blended, if necessary. For example, as a low molecular weight resin, a low molecular weight resin having a weight average molecular weight of 5,000 to 10,000 and a weight average molecular weight of 100,000 to 300,000
When the encapsulated particles are produced by blending the resin of the above in a ratio of 5/95 to 95/5, the dispersion is facilitated and the particle size distribution is improved. Further, it is easy to control the thickness of the resin coating the metal fine particles.

In the present invention, a polyester resin obtained by reacting a polyhydric alcohol with a polybasic acid or an ester derivative thereof can also be suitably used as the insulating resin.

Examples of polybasic acids include terephthalic acid,
Aromatic carboxylic acids such as isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid, maleic anhydride, fumaric acid, succinic acid,
Examples include aliphatic carboxylic acids such as alkenyl succinic anhydride and adipic acid, and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. One or more of these polybasic acids can be used. In addition, a combination of sulfoisophthalic acid, sulfoterephthalic acid, sulfophthalic acid, sulfosalicylic acid, sulfosuccinic acid, an alkyl ester of the above-mentioned sulfoacid, and a sodium salt may be appropriately mentioned.

Examples of polyhydric alcohols include aliphatic diols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and glycerin, and fatty acids such as cyclohexanediol, cyclohexanedimethanol and hydrogenated bisphenol A. Aromatic diols such as cyclic diols, bisphenol A ethylene oxide adducts, and bisphenol A propylene oxide adducts are exemplified. One or more of these polyhydric alcohols can be used.

The glass transition temperature of the polyester resin is 50
C. or higher, more preferably 60 ° C. or higher. If the temperature is lower than 50 ° C., heat resistance becomes insufficient, which is not preferable.

The content of the carboxyl group in the polyester resin is adjusted by controlling the mixing ratio of the polybasic acid and the polyhydric alcohol and the reaction rate to adjust the number of carboxyl groups present at the terminal of the polyester resin. Can be. Alternatively, by using trimellitic anhydride as the polybasic acid component, a branched resin having a carboxyl group in the main chain of the polyester resin can be obtained. The acid value of the polyester resin is preferably from 1 to 30, and more preferably from 2 to 20. By using a polyester resin having an acid value in this range, a charge amount suitable as an encapsulated particle for electrostatic image development can be easily obtained.

The weight average molecular weight (value measured by gel permeation chromatography in terms of polystyrene) of the THF-soluble portion of the polyester resin is 3,000 to 200,
000 is preferable, and 5,000 to 100,000
Is more preferable. If the weight average molecular weight is less than 3,000, the amount of resin dissolved in the aqueous medium after dispersion in the aqueous medium increases, the yield of encapsulated particles tends to decrease, and the crosslinking reaction does not proceed sufficiently, It is not preferable because the resin strength tends to be insufficient. If the weight average molecular weight is larger than 200,000, encapsulation becomes difficult, which is not preferable.

As the polyester resin, any type of linear, branched or crosslinked resin can be used. Here, a resin using a polyhydric carboxylic acid or polyhydric alcohol which is soluble in tetrahydrofuran and has three or more functional groups is referred to as a branched resin, and a resin not using the same is referred to as a linear resin. Further, a resin having a portion insoluble in tetrahydrofuran is referred to as a crosslinked resin. If necessary, a part of the insulating resin may be cross-linked after forming the encapsulated particles. In order to crosslink the polyester resin after the formation of the encapsulated particles, various glycidyl compounds and crosslinkers having a carbodiimide group described in the description of the means for crosslinking the styrene (meth) acrylic resin can be used.

Further, the polyester resin may be a system in which resins having different weight average molecular weights are blended, if necessary. For example, as a low molecular weight resin, a low molecular weight resin having a weight average molecular weight of 3,000 to 10,000 and a resin having a weight average molecular weight of 100,000 to 200,000 are mixed in 5/9.
When the encapsulated particles are produced by blending at a ratio of 5 to 95/5, the dispersion is facilitated and the particle size distribution is improved. Further, it is easy to control the thickness of the resin coating the metal fine particles.

The encapsulated particles of the present invention in which metal fine particles are coated with an insulating resin may contain other additives as necessary or may be externally added. For example, a charge control agent or a release agent (such as wax) commonly used in a dry developer by an electrostatic printing method is contained in the encapsulated particles of the present invention, or a glass frit, hydrophobic silica, titanium oxide or the like is used. And inorganic fine particles, or organic fine particles.

Examples of the charge controlling agent include nigrosine dyes, quaternary ammonium salts, Cr-containing dyes, Zn-containing dyes, Fe-containing dyes, Zr-containing dyes, molybdate chelate dyes, and fluorine-modified quaternary ammonium salts. And the like are appropriately selected and used according to the charging polarity.

Examples of the wax include a polypropylene wax, a polyethylene wax, a carnauba wax, a sasol wax and the like, and encapsulation of a regulating member (blade) and a developer carrier (developing roller) in a non-magnetic one-component developing device. This has the effect of reducing the problem of particles sticking.

The glass frit is included or externally added, and plays a role of baking metal fine particles and the like in encapsulated particles on the insulating inorganic substrate when sintering a wiring pattern printed on the substrate. It is in a dissolved or semi-dissolved state at the time of sintering, and is completely solidified when cooled to room temperature, and has an effect of immobilizing a metal or the like on the substrate.

Inorganic fine particles such as hydrophobic silica and titanium oxide, or organic fine particles are externally added to the encapsulated particles, and when used as a dry developer by an electrostatic printing method, physical properties such as fluidity and chargeability. Has the effect of improving
In the present invention, it is particularly preferable to use hydrophobic silica treated with silicone oil externally added to the surface of the encapsulated particles. By externally adding the silica, powder fluidity,
Transferability is improved, and a high-definition image can be obtained. This is because externally adding the fine powder to the particle surface reduces the contact area and reduces the adhesive force. The higher the sphericity of the encapsulated particles, the more uniform external addition becomes possible, Is significantly improved. It is particularly preferable that the silica is a hydrophobic silica treated with silicone oil, whereby the charging stability is improved and a high-definition image can be obtained.

As the hydrophobic silica treated with various silicone oils, for example, dimethyl silicone oil,
Hydrophobic silica treated with alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, fluorine-modified silicone oil, olefin-modified silicone oil, and the like. The external addition method is processed using a known and commonly used model. For example, a Henschel mixer, a super Henschel mixer, a hybridizer and the like can be mentioned.

The encapsulated particles for electrostatic image development of the present invention can be produced by dispersing metal fine particles and an insulating resin containing an acidic group in an aqueous medium in the presence of a base. More specific and preferred methods for producing the encapsulated particles of the present invention include, for example, a metal fine particle and an insulating resin containing an acidic group, and further, a mixture of an organic solvent in the presence of a base. A method of emulsifying in an aqueous medium to form encapsulated particles. A melt-kneaded product of an insulating resin containing an acidic group and metal fine particles is heated to a temperature higher than the softening point of the insulating resin, and is further pressurized, and mechanically stirred in an aqueous medium in the presence of a base. A method of forming encapsulated particles by emulsifying with the use of And the like. In order to completely encapsulate the metal fine particles by encapsulating the metal fine particles with the insulating resin, any of the above-mentioned manufacturing methods can be used, but the method for manufacturing the encapsulated particles for electrostatic image development of the present invention Is particularly preferred. According to the production method of (1), since a high shear by a mechanical stirring means is not applied when generating the encapsulated particles, the particle diameter of the produced encapsulated particles becomes more uniform.

In order to produce encapsulated particles by the production method described above, a self-water-dispersible resin, which is an insulating resin containing an acidic group, is dissolved in an organic solvent, and fine metal particles are added thereto. , Ball mill, bead mill,
By using a general mixer / disperser such as a sand mill and a continuous bead mill, a mixture in which metal fine particles are finely dispersed in a resin solution is produced. Next, the mixture is emulsified by mixing with an aqueous medium in the presence of a basic neutralizing agent, and further the organic solvent is removed under reduced pressure. The aqueous medium of the encapsulated particles in which the metal fine particles are coated with a resin ( Suspension). Thereafter, the encapsulated particles in which the metal fine particles are coated with the resin are separated from the aqueous medium and dried to obtain a dry powder of the encapsulated particles.

The mixture of the metal fine particles, the self-water-dispersible resin, and the organic solvent is mixed with the organic solvent solution of the self-water-dispersible resin, if the particle diameter of the metal fine particles is 3 μm or more, and the mixture is stirred by a stirring blade. It is possible to disperse by mixing. On the other hand, when the particle size of the metal fine particles is 1 μm or less, the cohesiveness becomes strong. Therefore, it is preferable to knead the fine particles by a wet method to obtain the above mixture.

The method for neutralizing the acidic group of the self-water dispersible resin in the above step with a base includes the following steps: (2) a method of preparing a mixture containing a self-water dispersible resin, metal fine particles and an organic solvent, followed by neutralization with a base, and (3) a method of preparing a neutralizing agent in an aqueous medium. A method in which the self-water-dispersible resin and the metal fine particles are mixed and charged therein, and the like can be mentioned.

The base used to neutralize the acidic group (carboxyl group) of the self-water dispersible resin is not particularly limited, and examples thereof include inorganic bases such as sodium hydroxide, potassium hydroxide and ammonia, and diethylamine and triethylamine. And an organic base such as isopropylamine.

The following can be used as the organic solvent for dissolving the self-water dispersible resin used in the present invention. For example, pentane, hexane, heptane,
Hydrocarbons such as benzene, toluene, xylene, cyclohexane and petroleum ether; halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene and carbon tetrachloride; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone , Ethyl acetate,
Esters such as butyl acetate are used. These solvents can be used alone or in combination of two or more. The organic solvent is preferably a polar solvent that dissolves the self-water dispersible resin and has an affinity for water.

Among the above-mentioned organic solvents, those having a solubility in water of 5 to 30% by weight are preferable, and those having a relatively low toxicity and a low boiling point which are easy to remove the solvent in the subsequent steps are preferable. An example of such a solvent is methyl ethyl ketone, which is particularly preferable as the organic solvent used in the present invention.

In the production method of the present invention, when a mixture of a self-water-dispersible resin, fine metal particles and an organic solvent added as required is mixed with an aqueous medium in the presence of a base and emulsified, It is preferable to add a phase inversion accelerator. The phase inversion accelerator referred to here has a different function from the emulsifier and the dispersion stabilizer. That is, the emulsifier and the dispersion stabilizer have a function of adsorbing on the surface of the encapsulated particles and having a function of stably dispersing the formed particles in an aqueous medium without fusing or agglomerating each other.

On the other hand, the phase inversion promoter used in the production method of the present invention refers to a substance having a phase inversion promoting function. That is, in the step of adding an aqueous medium (water or a liquid medium containing water as a main component) to a mixture of a self-water dispersible resin, metal fine particles, and an organic solvent added as needed, By gradually adding water to the phase, a discontinuous phase of Water in Oil is generated, and by adding additional water, the phase is changed to a discontinuous phase of Oil in Water, and the phase is converted into an aqueous medium. A suspension is formed in which the mixture is suspended as particles (droplets). At this time, Water in O
A substance having a function of smoothly promoting the phase inversion from a discontinuous phase of il to a discontinuous phase of Oil in Water is referred to as a phase inversion promoter.

The self-water-dispersible resin used in the present invention can be dispersed in an aqueous medium without using a phase inversion accelerator. However, in the present invention, by using the phase inversion accelerator, it becomes easy to produce suitable encapsulated particles having an average particle size, a particle size distribution, and the like.

The following can be used as the phase inversion accelerator in the present invention. Alcohol solvent Metal salt compound

Examples of the alcohol solvent include methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, t-butanol and sec.
-Butanol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether and the like can be used. Of course, other materials can be used. Among them, preferred are isopropanol, which is dissolved in water and has a low boiling point,
n-Propanol is preferred. The amount of the alcohol solvent used is generally 10 to 50 per 100 parts by weight of the resin solids.
It is on the order of parts by weight, but of course is not limited to this amount.

As the metal salt compound, known and commonly used ones can be used, but a divalent or higher valent metal salt which is soluble in water is preferred. For example, barium chloride, calcium chloride, cuprous chloride, cupric chloride, ferrous chloride, ferric chloride and the like can be mentioned. The amount of the metal salt compound used is the resin solid content 1
The amount is generally about 0.01 to 3 parts by weight per 00 parts by weight, but is not limited to this amount, of course.

In the production method of the present invention, when dispersing the metal fine particles and the self-water-dispersible resin in an aqueous medium, a homomixer (Tokusai Kika Kogyo Co., Ltd.), a slasher (Mitsui Mining Co., Ltd.), a Cavitron ( High shear emulsifying and dispersing machines such as Microfluidizer (Mizuho Industry Co., Ltd.), Menton-Gaulin Homogenizer (Gaulin Co., Ltd.), Nanomizer (Nanomizer Co., Ltd.), Static Mixer (Noritake Company) and continuous type Emulsifying and dispersing machines can also be used.

However, by using a phase inversion accelerator, encapsulated particles having a more uniform particle size can be obtained with stirring at a low shear than that obtained by a method with a high shear. As a method of low shear stirring, for example, using a stirrer, an anchor blade, a turbine blade, a Faudler blade, a full zone blade, a max blend blade, a half moon blade and the like as disclosed in JP-A-9-113535, The peripheral speed of the stirring blade is 0.2 to 5 m / s, more preferably 0.5 to 5 m / s.
A method of dropping water while stirring at a low shear of 4 m / s is preferred.

The dispersion of encapsulated particles obtained by coating the metal fine particles obtained by the above-described production method with a self-water-dispersible resin is obtained by first removing the organic solvent by means such as distillation.
The particles are separated from the aqueous medium and dried to obtain a powder of encapsulated particles.

When the self-water dispersible resin containing an acidic group is neutralized with a basic neutralizing agent, after forming the encapsulated particles and removing the organic solvent, for example, hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, Reverse neutralization treatment to return the hydrophilic group neutralized by the basic compound on the particle surface to the original functional group with an acidic neutralizing agent such as oxalic acid, further reducing the hydrophilicity of the functional group on the particle surface It is preferable to employ a method in which the powder is dried after drying.

As a method for separating the encapsulated particles from the aqueous medium, a natural sedimentation method utilizing a specific gravity difference, various centrifugal separators utilizing centrifugal force, or a filter cloth such as a filter press by decompression or pressurization. This is performed by filtration or the like.

For drying, any known and commonly used method can be employed. For example, drying may be performed under normal pressure or reduced pressure at a temperature at which the encapsulated particles do not fuse or aggregate, or freeze-drying may be performed. Drying may be performed using a continuous instantaneous air-flow dryer or a spray dryer. Examples of the drying apparatus described above include a Nauta mixer (manufactured by Hosokawa Micron), a ribocorn (manufactured by Okawara Seisakusho), and a flash jet dryer.

In the case where classification for adjusting the particle size distribution of the produced encapsulated particles or for removing coarse particles or fine particles is necessary, a known air-flow classifier is used after completion of drying. Classification can be performed by a conventional method. In addition, at the stage where the encapsulated particles are dispersed in the aqueous medium, using a method of classifying a water slurry of the encapsulated particles by a centrifugal separator, utilizing a difference in sedimentation depending on the particle size, or using a liquid cyclone or the like. It can also be carried out by a method of classifying the particles. For the removal of coarse particles,
It can be performed by filtering the water slurry of the encapsulated particles with a filter, a wet vibrating sieve, or the like. Since the encapsulated particles produced by the method of the present invention have a uniform particle size, encapsulated particles having a uniform particle size can be obtained without using these classification means, and even when used, by decantation. .

The electrostatic image developer of the present invention comprises encapsulated particles and a carrier, preferably a magnetic carrier whose surface is coated with a resin. As the core agent (magnetic carrier) of the carrier used in the present invention, iron powder, magnetite, ferrite and the like used in a normal two-component developing system can be used. Among them, the true specific gravity is low, the resistance is high, and the environmental stability is low. Excellent,
Ferrite or magnetite having good fluidity is preferably used. The shape of the core agent can be used without any particular limitation, such as a spherical shape and an irregular shape, but a spherical core agent is preferable. The average particle size is generally 10 to 500 μm, but for printing a high-resolution image, it is 30 to 100 μm.
Is preferred.

Examples of coating resins for coating these core agents include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether polyvinyl ketone, and vinyl chloride. / Vinyl acetate copolymer, styrene / acrylic copolymer, straight silicone resin comprising organosiloxane bond or its modified product, fluororesin, (meth) acrylic resin, polyester, polyurethane, polycarbonate, phenolic resin, amino resin, melamine resin , Benzoguanamine resin, urea resin, amide resin, epoxy resin and the like can be used. Among these, silicone resin and (meth) acrylic resin are particularly excellent in charge stability, coating strength and the like, and can be more preferably used.

The charge characteristics of the developer comprising the encapsulated particles and the carrier may be determined by measuring the amount of the resin covering the carrier, or by treating the surface of the core agent of the carrier with a silane coupling agent or by coating the carrier with carbon black or the like. Varies depending on the method of inclusion in the resin. The resin-coated carrier suitably used in the present invention uses ferrite or magnetite as a core agent and is coated with at least one resin selected from a silicone resin and a (meth) acrylic resin. Is a resin-coated magnetic carrier whose surface is treated with a silane coupling agent or the like, and the charge amount of the encapsulated particles, the charge amount distribution, and the amount of the oppositely charged particles are preferably adjusted by the above-described means.

The method of coating the surface of the carrier core material with the resin is not particularly limited. However, a dipping method of dipping in a solution of the coating resin, a spray method of spraying the coating resin solution onto the surface of the carrier core material, or a carrier method is used. Fluidized bed method in which the carrier is sprayed while being floated by flowing air, a kneader coater method in which a carrier core material and a coating resin solution are mixed in a kneader coater, and a solvent is removed.

The solvent used in the coating resin solution is not particularly limited as long as it dissolves the coating resin. For example, toluene, xylene, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane and the like can be used. The thickness of the coating layer on the carrier surface is usually 0.1
〜3.0 μm.

The carrier preferably used in the present invention, which is coated with a resin, is subjected to a heat treatment as required. In particular, when coated with a resin containing a cross-linking component, the film is reinforced by a heat cross-linking reaction, so that a more durable carrier is preferable. Further, when the heat treatment is performed, the charge amount when mixed with the toner can be controlled depending on the temperature condition. Generally, the higher the heating temperature, the higher the charge amount tends to be.
Usually, the heat treatment is performed at a temperature of 100 ° C to 300 ° C for 10 minutes to 5 hours. After the heat treatment, the carriers may be fixed to each other, so that stress may be applied to loosen the carrier particles.

The weight ratio between the encapsulated particles and the resin-coated magnetic carrier is not particularly limited, but the specific gravity of the encapsulated particles may be high. 30% by weight, more preferably 1%
0 to 25% by weight. If the amount is less than 5% by weight, the charge amount increases and the number of oppositely charged particles decreases, but the transfer amount decreases, which is not preferable. On the other hand, when the content is more than 30% by weight, triboelectric charging becomes insufficient, tending to lower the rise of charging and increasing the number of oppositely charged particles, which is not preferable.

To form a conductive wiring pattern for an electronic circuit on an insulating inorganic substrate using the encapsulated particles of the present invention, the encapsulated particles are used as a developer for developing an electrostatic image. A wiring pattern is printed on the insulating inorganic substrate by electrophotography. Thereafter, the wiring pattern is sintered to produce a metal conductive wiring pattern. At this time, since the particle diameter of the metal fine particles contained in the encapsulated particles is small, a smooth and dense conduction path is obtained, and low resistance is achieved.

[0102]

EXAMPLES The present invention will be described in more detail with reference to resin synthesis examples and examples, but the present invention is not limited to these examples. In the following, “parts” means “parts by weight”, and “water” means “deionized water”.

(Synthesis Example 1 of Insulating Resin) 114 parts of methyl ethyl ketone, 12 parts of isopropyl alcohol and water 2
After placing 4 parts in a reaction vessel and heating to 80 ° C., a mixture of the following monomers was charged at once in a nitrogen stream to start the reaction. Acrylic acid 54.0 parts Styrene 364.8 parts Butyl acrylate 181.2 parts "Perbutyl O" 0.6 parts

After 3 hours from the start of the reaction, every 1 hour,
About 10 parts of the reaction resin solution was sampled, diluted with the same amount of methyl ethyl ketone, and the viscosity was measured with a Gardner viscometer. When the viscosity became MN, a mixed solvent consisting of 567 parts of methyl ethyl ketone and 63 parts of isopropyl alcohol was added. The residual monomer ratio at this time was determined by gas chromatography to calculate the polymerization ratio.
1%. After heating the temperature of the reaction solution to 80 ° C,
A mixture of the following monomers was added dropwise over 1 hour. Acrylic acid 54.0 parts Styrene 456.6 parts Butyl acrylate 89.4 parts "Perbutyl O" 18.0 parts

After the completion of the dropwise addition, 2 parts of “Perbutyl O” (a catalyst manufactured by NOF Corporation) were added 3 times every 3 hours.
The reaction was continued for another 4 hours. After completion of the reaction, the resin solution was heated to remove the solvent, thereby obtaining a solid resin. This resin has a molecular weight distribution of two peaks, and its weight average molecular weight is 1
10,000 (a value measured by gel permeation chromatography in terms of polystyrene). When the two peaks are separated by a peak boundary, the weight average molecular weight is 3
Can be split into two parts 5,000 and 360,000,
The ratio was 78:22. The acid value of this resin is 70,
The glass transition temperature was 60 ° C. Hereinafter, this resin is referred to as R
Abbreviated as -1.

(Synthesis Example 2 of Insulating Resin) 450 parts of methyl ethyl ketone was placed in a reaction vessel and heated to 80 ° C.
A mixture having the following ratio was dropped in a nitrogen stream over 2 hours to carry out a reaction. 9.0 parts of acrylic acid 282.0 parts of styrene 9.0 parts of butyl acrylate 15.0 parts of “perbutyl O” 13.0 parts of “perbutyl O” Then, after completion of the dropping, 3 parts of perbutyl O were added 3 times every 3 hours. The reaction was continued for another 4 hours. Thereafter, the solvent was removed to obtain a solid resin. The resin has a glass transition temperature of 60 ° C. and a weight average molecular weight of 510.
The acid value was 0. Hereinafter, this resin is abbreviated as R-2.

(Surface Treatment Method D-1 for Metal Fine Particles) The metal fine particles are charged into a hot air drier and heated at 100 ° C. for 30 minutes to oxidize the surface of the metal fine particles. Next, water / isopropyl alcohol / aminosilane coupling agent (SH6020) (manufactured by Toray Dow Corning) was added to 93 /
The weight ratio is adjusted to 5/2, and the mixture is left for 90 minutes to hydrolyze the silane coupling agent. Thereafter, the same amount of metal fine particles as the aminosilane hydrolysis solution is charged and immersed for 18 hours to adsorb aminosilane on the surface of the metal fine particles. After completion of the immersion, solid-liquid separation is performed by suction filtration or the like, dehydration condensation reaction is performed in a hot air dryer at 120 ° C. for 2 hours, and further, aggregates are crushed by a Henschel mixer, and coarse particles are removed by a sieve. To obtain a surface-treated product. The above surface treatment method is designated as D-1.

(Surface Treatment Method D-2 for Metal Fine Particles)
Isopropyl alcohol / aminosilane coupling agent (SH6020) (manufactured by Toray Dow Corning Co., Ltd.)
, And left for 90 minutes to hydrolyze the silane coupling agent. Thereafter, the same amount of metal fine particles as the aminosilane hydrolysis solution was charged and immersed for 18 hours.
Aminosilane is adsorbed on the surface of metal fine particles. After completion of the immersion, solid-liquid separation is performed by suction filtration or the like, a dehydration condensation reaction is performed at 120 ° C. for 2 hours by a hot air drier, and aggregates are crushed by a Henschel mixer, and coarse particles are removed by a sieve. To obtain a surface-treated product. The above surface treatment method is referred to as D-2.

Table 1 shows the fine metal particles treated by the above surface treatment method.

[0110]

[Table 1]

The average long axis / short axis diameter of the metal fine particles is represented by S
It was shown as an average value of 100 pieces from the EM photograph. The average circularity is measured by a flow-type particle image analyzer FP manufactured by Toa Medical Electronics Co., Ltd.
It measured using IP-1000. The volume average diameter was measured using a Coulter Multisizer (2).

(Production Example 1 of Encapsulated Particles) R-1 Resin 1
35 parts of R-2 resin and 15 parts of methyl ethyl ketone 278
Parts of a resin solution, 150 parts of C-1 copper powder, 25.8 parts of 1N aqueous sodium hydroxide solution, and 54.9 parts of isopropyl alcohol as a phase inversion accelerator were charged into a reaction vessel. After sufficiently stirring until dissolution, 120 parts of water is added and the mixture is further stirred, and the temperature is adjusted to 30 ° C. Thereafter, 30 parts of water was added dropwise while stirring at a peripheral speed of 1.05 m / sec to perform phase inversion emulsification, and further diluted with 300 parts of water to obtain a dispersion of encapsulated particles in which copper particles were encapsulated. Next, the organic solvent is removed by distillation under reduced pressure, and then P
H was set to 3. Next, after the encapsulated particles containing no copper powder were removed by a centrifuge, the encapsulated particles were separated from the aqueous phase and washed with water. The obtained wet cake was dried with a vacuum drier to obtain a powder of encapsulated particles. The volume average particle size of these particles is 7.7 μm
The amount of the insulating resin coating resin was 7.0% by weight.
Here, a water slurry of the encapsulated particles was transferred to an optical microscope (6).
When the state of encapsulation was observed with transmitted light, the individual copper particles were completely encapsulated with the resin. In addition, it was confirmed that the shape was almost spherical. Hereinafter, it is described as MC-1.

(Example 2 of preparation of encapsulated particles) 1 of R1 resin
To a solution of 50 parts in 291 parts of methyl ethyl ketone, 300 parts of C-4 silver powder, "TETRAD-X"
7.5 parts of (N, N, N ', N'-tetraglycidylmethaxylenediamine manufactured by Mitsubishi Gas Chemical Industry; average number of glycidyl functional groups 4, glycidyl group equivalent 100 g / eq),
28.5 parts of a 1N aqueous sodium hydroxide solution and 52.5 parts of isopropyl alcohol as a phase inversion promoter were charged into a reaction vessel, and 500 parts of water was added dropwise with stirring to emulsify the phase to emulsify the silver particles. A dispersion of encapsulated particles was obtained. Next, after removing the organic solvent by distillation under reduced pressure, a crosslinking reaction was carried out at 70 ° C. for 4 hours while stirring.

After cooling, 1N hydrochloric acid was added to adjust the pH of the liquid medium.
After that, the silver encapsulated particles were separated from the aqueous phase by a centrifugal separator, washed with water, and dried by a freeze dryer to obtain a powder of encapsulated silver powder. The volume average particle size of the particles was 3.8 μm as measured by a Coulter Multisizer, and the amount of coating resin was measured using a carbon analyzer “HORIBA EMIA-110” to be 6.8% by weight. . In addition, these particles were
(Scanning electron microscope), it was almost spherical. Here, when the water slurry of the encapsulated particles was observed with transmitted light using an optical microscope (600 times), each of the silver particles was completely encapsulated with the resin. Even when these particles were added to methyl ethyl ketone, no dissolution or swelling of the resin coating layer was observed. Hereinafter, it is referred to as MC-2.

Table 2 shows the properties and treatment methods of the encapsulated particles produced. MC-3 to MC-5 are MC-1
It was manufactured in the same manner as described above.

[0116]

[Table 2]

The amount of the resin in Table 2 is the amount of the insulating resin in the encapsulated particles, and is the same as “Carbon Analyzer E” manufactured by Horiba, Ltd.
MIA-110 ". The particle size and particle size distribution were measured using a Coulter Multisizer II manufactured by Coulter Beckman. Dv50 is the 50% volume average diameter, and Dv50 / Dn50 is the ratio of the volume and the 50% average diameter of the number. GSD is the square root of the value obtained by dividing the 84% volume average diameter by the 16% volume average diameter. The circularity distribution was measured by a flow-type particle image analyzer FPIP-10 manufactured by Toa Medical Electronics Co., Ltd.
00 was measured. The encapsulation state was observed by a transmitted light using an optical microscope (magnification: 600) in a state where the encapsulated particles were dispersed in water.の も の indicates that the resin layer contained some water droplets, △ indicates that no metal fine particles were exposed, but water droplets were captured in the resin layer,
Those with exposure were evaluated as x.

(External Addition of Hydrophobic Silica) To 100 parts of each encapsulated particle of MC-1 to 0.5, 0.5 part of hydrophobic silica (H-1018) treated with silicone oil manufactured by Clariant was added to Henschel. Externally added with a mixer.

(Preparation of developer) Encapsulated particles MC-1
Developing agents of Examples 1 to 5 and Comparative Examples 1 to 3 below were prepared using samples in which hydrophobic silica was externally added to Nos. 1 to 5.
The conditions for preparing the developer are as follows.・ Mixing container: made of polypropylene with a volume of 250 ml ・ Mixing conditions: 120 rpm with a ball mill, mixing time 30
Minutes

(Example 1) Externally added encapsulated particles of MC-1, a manganese ferrite as a core agent, a dimethyl silicon resin as a coating resin, and a carrier 1 having a particle diameter of 60 microns and a surface of the core agent treated with an aminosilane coupling agent. 20/80 (wt%) encapsulated particles / carrier using
Of a developer was prepared.

(Example 2) Externally added encapsulated particles of MC-2, manganese ferrite as a core agent, dimethylsilicone resin as a coating resin, and a carrier 2 having a particle diameter of 60 microns and a surface of the core agent treated with an aminosilane coupling agent. 24/76 (wt%) encapsulated particles / carrier using
Of a developer was prepared. Carrier 2 has a treatment amount of an aminosilane coupling agent that is 比 べ that of Carrier 1
It has become.

(Example 3) Using the encapsulated particles externally added of MC-3 and the carrier 1 used in Example 1, a developer was prepared at a ratio of encapsulated particles / carrier of 21/79 (% by weight). Prepared.

(Example 4) Using the encapsulated particles externally added of MC-4 and the carrier 2 used in Example 2, the developer was added at a ratio of 21/79 (% by weight) of encapsulated particles / carrier. Prepared.

Example 5 Using the encapsulated particles externally added to MC-5 and the carrier 2 used in Example 2, the developer was added at a ratio of 20/80 (% by weight) of encapsulated particles / carrier. Prepared.

(Comparative Example 1) Using the encapsulated particles externally added of MC-1 and the carrier 1 used in Example 1, the developer was used at a ratio of 4/96 (% by weight) of encapsulated particles / carrier. Prepared.

(Comparative Example 2) Encapsulated particles having externally added MC-1, a core agent of manganese ferrite, a coating resin of dimethyl silicon resin, and a carrier 3 containing carbon black in the coating resin and having a particle diameter of 60 microns. Thus, a developer was prepared at a ratio of encapsulated particles / carrier of 20/80 (% by weight).

(Comparative Example 3) Encapsulated particles / carrier was 20% using externally added encapsulated particles of MC-1, a carrier 4 having a core agent of manganese ferrite and a coating resin of dimethyl silicon resin having a particle diameter of 60 microns. A developer was prepared at a ratio of / 80 (% by weight). Using the developers of Examples 1 to 5 and Comparative Examples 1 to 3, measurement was performed under the following conditions.

(Measurement of Charging Characteristics) Using an E-SPART analyzer, the charge amounts of the encapsulated particles contained in the developers of Examples 1 to 5 and Comparative Examples 1 to 3, the standard deviation of the charge amount distribution, and the reverse. The proportion of charged particles was measured. The measurement conditions are as follows. -Measurement conditions of E-SPART analyzer:-Blow pressure: 0.02 MPa-Number of counted particles: 3000-Potential difference between electrodes: 100 V The true specific gravity of the encapsulated particles required for calculation was determined as follows. True specific gravity value of encapsulated particles: The true specific gravity of the encapsulated particles was determined by the following method because the true specific gravity varies depending on the amount of resin.
5 g of the encapsulated particles are placed in a 10 mmφ molding machine, compression-molded at a pressure of about 20 MPa, and the weight is precisely weighed (A). Pour 5 ml of water into a 10 ml graduated cylinder, put the molded product in it,
The volume of the molded article is determined (B). The true specific gravity is obtained by A / B. Table 3 shows the measurement results.

(Evaluation of Developer Image) The developer composed of the externally added resin particles and the carrier obtained in Examples and Comparative Examples was filled in a two-component copying machine (MF-530, manufactured by Ricoh Company), and a wiring pattern was prepared. Was printed, and the printed image was evaluated. The print image was evaluated for edge reproducibility, fog, and fine line reproducibility. The reproducibility of the edge indicates the smoothness of the conductor interface when baked after printing, and it is not preferable in a printed image having a distorted edge because the resistance value in a high frequency region when the conductor is formed becomes high.も の indicates that the edge was reproduced clearly, △ indicates that the edge was slightly disturbed, and X indicates that the edge was remarkably disturbed.

(Evaluation of fog) If there is a lot of fog, a short circuit may occur when a conductive pattern is formed.も の indicates that there was little fog and there was no possibility of short-circuit, Δ indicates that the fog was slightly covered, and x indicates that there was much fog and there was a possibility of short-circuit. Table 3 shows the evaluation results.

(Fine Line Reproducibility) The fine line reproducibility indicates the resolution of the conductive pattern, and those having inferior fine line reproducibility are not preferable because they may not conduct.も の indicates that the fine line was reproduced clearly, △ indicates that there was slight disturbance, and X indicates that there was significant disturbance.

[0132]

[Table 3]

From Table 3, it can be seen that all of the developers of Examples 1 to 5 of the present invention have good print image reproducibility and no problem. On the other hand, Comparative Example 1 has a high charge amount,
The transfer amount is reduced, and the edges and thin lines are blurred.
Good images were not reproduced. In Comparative Example 2, since the charge amount was low and the number of particles of the opposite charge was large, the image was fogged, and both the edge portion and the thin line portion became unclear. Comparative Example 3 has a broad charge amount distribution with a wide standard deviation of the charge amount distribution. As a result, the entire image reproducibility became nonuniform, and image unevenness occurred.

As can be seen from the evaluation results in Table 3,
It can be seen that a good printed image of a conductive pattern can be obtained by the charging characteristics of the developer, particularly, an appropriate charge amount, a sharp charge amount distribution, and a small amount of oppositely charged particles. As a result, good conduction can be obtained even when the conduction path is formed by sintering the pattern. After the solid image is developed, 15
After performing hypothetical deposition by heat treatment at 0 ° C. for 2 hours, the operations of development and hypothetical deposition were further repeated twice to produce a thick film on which a solid image was laminated, and the image was cut to obtain a fractured surface. SEM
Upon observation, the particles were densely packed. This is due to the sharp particle size distribution and high sphericity of the encapsulated particles, which is suitable for good conduction after termination.

[0135]

The developer of the present invention has a charge characteristic of the developer,
In particular, since the charge amount is appropriate, the distribution of the charge amount is sharp, and the number of oppositely charged particles is small, it has excellent developing characteristics that enable high-density and high-precision wiring pattern printing by an electrostatic recording method or an electrophotographic method. Further, it is possible to print a wiring pattern in which the encapsulated particles are densely filled. Furthermore,
When the printed wiring pattern is sintered and the insulating resin is completely burned, the metal fine particles are packed most closely to form a high-precision, low-resistance conductive pattern with no voids or defects. Is possible.

Claims (15)

[Claims] 1. A developer comprising at least an encapsulated particle for electrostatic charge image development having at least a metal fine particle and a coating of an insulating resin for encapsulating the fine particle, and a carrier, wherein the developer is measured by a charge amount distribution measuring device. The absolute value of the charge amount of the encapsulated particles is | 1.8 to 3.8 | (femtoC / 1
0 μm), the standard deviation of the charge amount distribution is 2.5 or less, and 95% by number or more of encapsulated particles charged to the same polarity are contained. 2. The method according to claim 1, wherein the metal fine particles are gold, platinum, palladium, silver, ruthenium, rhodium, osmium, iridium, nickel, cobalt, copper, zinc, lead, aluminum, titanium, vanadium, chromium, manganese, zirconium, molybdenum, indium. 2. The electrostatic image developer according to claim 1, wherein the developer is at least one metal selected from the group consisting of antimony, tungsten, and tungsten. 3. The encapsulated particles, wherein (1) the (a) volume average particle diameter of the encapsulated particles is 0.5 to 20.
(b) 50% volume average particle size / 50% number average particle size is 1.25 or less, and (c) (84% volume average particle size / 16% volume average particle size) has a square root of 1 (2) (a) the ratio of the encapsulated particles contained in the range of the circularity of 0.98 to 1.00 is 80% by number or more, and (b) the circularity is 0.95 or less. The number% of the range is 6
% Or less, the electrostatic image developer according to claim 1. 4. The electrostatic image developer according to claim 1, wherein a ratio of the insulating resin to the encapsulated particles is 20% by weight or less. 5. The method according to claim 1, wherein the insulating resin is an acidic group-containing resin.
Item. The electrostatic image developer according to item 1. 6. The electrostatic image developer according to claim 1, wherein the insulating resin is a cross-linked resin. 7. The method according to claim 1, wherein hydrophobic silica treated with silicone oil is attached to the surface of the encapsulated particles.
Item. The electrostatic image developer according to item 1. 8. The electrostatic image developer according to claim 1, wherein the encapsulated particles are negatively chargeable particles. . 9. A wiring pattern is printed on an insulating inorganic substrate using an electrostatic charge image developer, and thereafter, the wiring pattern is sintered to form a metal conductive wiring pattern on the insulating inorganic substrate. In the method for forming, the developer is a developer comprising encapsulated particles for electrostatic image development having at least metal fine particles and a coating of an insulating resin for encapsulating the metal particles, and a carrier, and a charge amount distribution measuring device The absolute value of the charge amount of the encapsulated particles measured by | 1.8-3.8 | (femtoC / 10μ
m), wherein the standard deviation of the charge amount distribution is 2.5 or less, and 95% by number or more of encapsulated particles charged to the same polarity are contained. 10. In the encapsulated particles, (1)
(A) the volume average particle diameter of the encapsulated particles is 0.5 to 2;
0 μm, (b) 50% volume average particle diameter / 50% number average particle diameter is 1.25 or less, and (c) (84% volume average particle diameter / 16% volume average particle diameter) has a square root of 1 (2) (a) the ratio of the encapsulated particles contained in the range of the circularity of 0.98 to 1.00 is 80% by number or more, and (b) the circularity is 0.95 or less. 10. The method according to claim 9, wherein the number% of the range is 6% or less. 11. The method for forming a conductive wiring pattern according to claim 9, wherein a ratio of the insulating resin to the encapsulated particles is 20% by weight or less. 12. The method for forming a conductive wiring pattern according to claim 9, wherein the insulating resin is an acidic group-containing resin. 13. The method for forming a conductive wiring pattern according to claim 9, wherein the insulating resin is a cross-linked resin. 14. The method according to claim 9, wherein hydrophobic silica treated with silicone oil is adhered to the surface of the encapsulated particles. A method for forming a conductive wiring pattern. 15. The method according to claim 9, wherein the encapsulated particles are negatively chargeable particles.
15. The method for forming a conductive wiring pattern according to any one of 13 and 14.