JPH11194526A - Elerctrophotographic image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print and form a conductor pattern on a green sheet with high precision, and form the conductor pattern having excellent conductiveness after baking and having high reliability by using an insulation surface-treated metal particle having both a high metal particle ratio and a high insulation property, and by making electrostatic charge uniform by the high insulation property. SOLUTION: In this image forming method, used is a developer comprising an insulation surface-treated metal particle in which the surface of a metal particle is covered to be insulated with a thermoplastic insulating material, and of which mean particle size is within the range of 2-20 μm, and carrier particles having 40-120 μm of mean particle size. The surface-treated metal particle is charged by the carrier particle, and an electrostatic latent image formed on a photosensitive member by electrophotography is contact-developed to form a clear image comprising the surface-treated metal particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming method using insulated surface-treated metal particles in which metal particles are surface-treated and insulated, and the image forming method includes forming a conductive pattern on a ceramic green sheet. Used for

[0002]

2. Description of the Related Art Conventionally, in forming a conductor pattern such as an electrode of a ceramic multilayer capacitor or the like, a metal such as copper or tungsten is coated on a thin green sheet composed of a ceramic powder such as silica / alumina and an organic binder. The particle paste was formed into a pattern by screen printing and fired to form an electrode pattern.
However, in this method, a screen composed of a mesh-like mesh is used, so that the printing accuracy is reduced due to dripping of the screen after durability, the material loss for creating a screen for each pattern, and the material loss adhering to the mesh. There was a problem that would occur.

In order to solve the above-mentioned drawbacks, Japanese Patent Laid-Open Publication No.
JP-A-189617, JP-A-59-202682, JP-A-60-137886, and JP-A-60-160690 describe that an electrode pattern of conductive particles is formed by electrophotography, and the electrode is fired. I have.
Specifically, for example, a tungsten powder and a styrene acrylic resin are kneaded, pulverized and classified to obtain 10 to 20 μm printing particles (toner). An electrode pattern is formed. However, since the printing particles in these systems have low resistance and easily leak electric charges, it has been difficult to reproduce a pattern with high precision in an electrophotographic apparatus, and to form a reliable conduction path.

[0004]

The above-mentioned conventional printing particles have a particle structure that does not lead to the formation of high-resistance particles, resulting in non-uniform charging. That is, if sufficient metal powder for forming a conductive path is added to the particles after firing, the amount of resin relatively decreases, the amount of metal powder exposed on the particle surface increases, and the particles have low resistance. On the other hand, when the resistance is increased by increasing the amount of the resin, the number of metal particles is reduced, and it is difficult to form a conductive path, which is the original purpose. Therefore, in the conventional method using printing particles, it is difficult to form an image by an electrophotographic method in which the particles are controlled as charged particles. Therefore, an object of the present invention is to form a conductor pattern with higher precision and higher reliability than a conventional system using electrophotography.

[0005]

According to the electrophotographic image forming method of the present invention, the surface of a metal particle is coated with a thermoplastic insulating material to be insulated, and the insulated surface having an average particle size in a range of 2 to 20 μm is provided. Treated metal particles, average particle size 40 to 120 μm
Using a developer consisting of carrier particles, the carrier particles charge the insulated surface-treated metal particles, and the electrostatic latent image formed on the photoreceptor by electrophotography is contact-developed,
It is characterized in that a visible image is formed from the insulated surface-treated metal particles. The insulated surface-treated metal particles used in the present invention can contain a large amount of metal particles, and since the surface is firmly covered with a thermoplastic resin, the particles are an insulator, and are stably and uniformly charged. There is no charge leakage. Therefore, it can be suitably used as a toner in a developer for electrophotography, and is particularly suitable for printing a conductor pattern on a ceramic green sheet.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The insulated surface-treated metal particles used in the present invention are obtained by coating the surfaces of metal particles with a thermoplastic insulator. As the metal particles, any one can be used,
When a conductor pattern is to be printed on a ceramic green sheet, copper, tungsten, nickel, silver, or the like is used. The selection of the metal is determined by conditions such as the firing temperature. For example, when the inorganic material used for the green sheet is silica, copper is suitable as the conductive metal, and when the inorganic material is alumina, tungsten is suitable. Various synthetic resins are used as the thermoplastic insulator. When a conductor pattern is to be printed on a ceramic green sheet, it is necessary to eliminate the ceramic green sheet during firing, and a polyolefin resin such as polyethylene is preferable.

The method of coating the surface of the metal particles is not particularly limited, but it is desirable to completely cover the surface of the metal particles without substantially exposing the surface, and moreover, a method capable of realizing this with a small amount of thermoplastic insulating material. Is preferred. As this method, for example, there is a method in which a monomer is polymerized directly on the surface of a metal particle to form a thermoplastic resin layer. Specifically, for example, a catalyst is adsorbed on the surface of the metal particle, ethylene gas or the like is supplied, and the monomer gas is polymerized directly on the surface of the metal particle to form a polyethylene resin film. Although this method is a method for producing carrier particles, Japanese Patent Application Laid-Open No.
It is described in detail in JP-A-87770, JP-A-2-187777, and the like, and can be directly applied to the production of the insulated surface-treated metal particles of the present invention.

In the present invention, the average particle size of the insulated surface-treated metal particles is 2 to 20 μm, preferably 3 to 10 μm. If the average particle size is too large or too small, it is difficult to control electrostaticity, and ground fog or the like occurs, and the image level is reduced. When the average particle size is large, fine pattern printing cannot be performed. The insulated surface-treated metal particles used in the present invention are mixed with a carrier as a toner and used as an electrophotographic developer. In the electrophotographic method, the toner is controlled mainly by an electrostatic force, so that it is required to stably and uniformly charge the toner. Therefore, the insulated surface-treated metal particles of the present invention are required to be insulators, and the resistance value of the particles is preferably 10 ¹² Ω · cm or more, more preferably 10 ¹³ Ω · cm or more. If the particle resistance value is less than 10 ¹² Ω, fogging of the ground and poor transfer tend to occur. In order to increase the insulating property, it is conceivable to increase the total amount of the insulator. However, if the amount is excessively increased, the amount of the conductor after firing decreases, and it becomes difficult to obtain conduction of the conductor pattern. In general, the thickness of the conductive path on the pattern is required to be 15 μm or more, and considering the specific gravity difference between the metal and the insulator, the filling rate of particles on the sheet after transfer, the amount of particles that can be controlled by electrophotography, etc. The amount of the insulator in the insulated surface-treated metal particles is preferably 20% by weight or less, more preferably 15% by weight or less. In order to ensure a pattern thickness of 15 μm or more after firing, the layer thickness of the insulated surface-treated metal particles (toner particles) formed after development is preferably 20 to 50 μm, and more preferably 25 to 50 μm.
μm. If the layer thickness is too large, problems such as bleeding occur.

The insulated surface-treated metal particles (toner particles) of the present invention are mixed with a carrier to form a developer, and an electrophotographic printing method using a two-component developing method is applied. In this case, the particle size of the carrier is preferably from 40 to 120 μm, more preferably from 40 to 100 μm. If the particle size of the carrier is too small, the carrier will be developed, while
If it is too large, the charge of the particles will decrease, and fog will occur. As the carrier, an iron powder carrier, a ferrite carrier or the like is used. The content of the insulated surface-treated metal particles of the present invention in the developer is preferably from 2 to 20% by weight, more preferably from 3 to 10% by weight. If this content is less than 2% by weight, the carrier is developed, while if it exceeds 20% by weight, background fog occurs.

FIG. 1 shows an electrophotographic apparatus used in the present invention, which is not different from a general apparatus. That is, a drum-shaped photoconductor 11 such as an amorphous silicon
Around the charging member 13, the image signal exposure member 15, the developing member 17, the transfer member 19, the cleaning blade 2
1. An overall exposure member 23 is provided. By using an amorphous silicon-based photoreceptor with excellent printing durability,
Maintenance is facilitated, and an apparatus with less material loss is provided. In the present invention, a developer containing the insulating surface-treated metal particles of the present invention as a toner is supplied to the developing member 17. An electrostatic latent image of a conductor pattern is formed by the image signal exposure member 15 on the photoreceptor 11 uniformly charged in the dark by the charging member 13, and the electrostatic latent image is developed by contact with the developing member 17 to form Is formed on the surface of the photoconductor 11. The linear speed between the rotation speed of the drum-shaped photoreceptor 11 and the rotation speed of the developing member 17 with respect to the developing sleeve is 1.0 to 5.0, preferably 1.5 to 5.0. If the rotation speed of the developing sleeve is too low, the amount of development is insufficient, while if it is too high, bleeding or the like occurs.

Next, a thin sheet (green sheet) composed of a ceramic powder such as silica or alumina and an organic binder is supplied between the photoreceptor 11 and the transfer member 19, and a toner image is formed on the ceramic green sheet. Is transferred. In the present invention, since the insulated surface-treated metal particles used as the toner have high resistance and can be stably and uniformly charged, the control in the development process and the transfer process is easy, and a high-precision pattern is formed on the green sheet. printing,
Can be formed. The members around the photoconductor 11 in FIG. 1 can be variously changed. For example, a conductive brush or a conductive roller can be used as the charging member 13 instead of the corona charging device.

The green sheet on which the pattern is formed is
Heating to an appropriate temperature, for example, 800 ° C. or more, and sintering, the insulator is eliminated to obtain a conductor pattern. Although the insulated surface-treated metal particles of the present invention have a high resistance value and can be uniformly charged, since there are many portions occupied by the metal particles,
After firing, a conductive pattern with good conduction and high reliability can be obtained. In addition, utilizing the fact that the insulator of the insulated surface-treated metal particles is thermoplastic, a suitable amount of heat (for example, 200 ° C. or less) is applied during the period from forming the pattern on the green sheet to firing. It is also possible to make a provisional attachment, or to temporarily fix the adhesive by spraying it onto the pattern on the green sheet.

[0013]

According to the electrophotographic image forming method of the present invention, uniform charge can be achieved by high insulating properties by using insulating surface-treated metal particles having both a large metal particle ratio and high insulating properties. Thus, a conductor pattern can be printed and formed on the green sheet with great precision, and a highly reliable conductor pattern having good conduction after firing can be formed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Using the electrophotographic image forming apparatus shown in FIG.
A conductor pattern was printed on the ceramic green sheet. Here, an amorphous silicon photosensitive member having a photosensitive layer thickness of 25 μm was used as the photosensitive member. As the insulated surface-treated metal particles used as the toner, an ethylene monomer is directly polymerized on copper powder, and silica is applied to particles having an average particle diameter of 6 μm coated with copper powder with a polyethylene resin having a weight ratio of 6% by weight. Externally added toner particles (metal particles) were used. A toner consisting of ferrite particles having an average particle diameter of 70 μm was mixed with the toner particles (metal particles) at a content of 8% by weight to form a developer, and an image of a conductor pattern was formed. Image forming conditions were set as follows. Photoconductor charge potential: 350 V After exposure Potential: 15 V Current image potential: 120 V Photoconductor drum linear speed: 60 mm / sec Current image linear speed: 120 mm / sec Developing sleeve rotation speed (linear speed ratio to photoconductor drum rotation speed) : 2.0 times

After the formed conductor pattern is formed on a green sheet containing silica as a main component by electrophotography, it is sintered at 900 ° C. for 1 hour in a reducing atmosphere to form a copper on a ceramic substrate. A conductor pattern was formed. Under the above conditions, the following experiment was performed as a base, and the influence of each condition parameter was confirmed. (1) Carrier Particle Size Image formation was performed by changing the carrier particle size between 30 and 130 μm, and the image characteristics were evaluated. The results are shown in Table 1. It can be seen that a good pattern is formed at 40 to 120 μm, especially at 40 to 100 μm. (2) Content of Metal Particles (Toner Particles) in Developer The content of metal particles (toner particles) in the developer is 1 to
The image characteristics were evaluated by changing the range of 23% by weight, and the results are shown in Table 2. Metal particle content of 2 to 20% by weight
And a good pattern was formed.

(3) Resistance Value of Metal Particles The thickness of the polyethylene resin layer formed on the metal particles is adjusted to change the resistance of the insulated surface-treated metal particles (toner particles) to evaluate image characteristics. Table 3 shows the results. It can be seen that an excellent pattern image is formed by setting the resistance to 10 ¹² Ω or more. (4) Content of insulator in metal particles The amount of insulator contained in insulated surface-treated metal particles (toner particles) in which the amount of polyethylene resin formed on metal particles is adjusted is controlled and formed after firing. The specific resistance of the conductor pattern was measured, and the results are shown in Table 4. It can be seen that by setting the insulator content to 20% by weight or less, stable conduction after firing can be obtained.

(5) Number of rotations of developing sleeve The number of rotations of the developing sleeve with respect to the photosensitive drum was changed to form toner images of various thicknesses (thickness after development), and the pattern thickness and pattern specific resistance after firing were evaluated. Table 5 shows the results. A good pattern was obtained when the rotation speed of the developing sleeve was in the range of 1.0 to 5.0 times the linear speed ratio with respect to the rotation speed of the photosensitive drum. At this time, the film thickness of the developer after development is 20 to 50 μm.
A pattern of 5 to 38 μm was formed, and stable conduction was obtained.

[0018]

Table 1: Relationship between carrier particle size and image characteristics Carrier particle size (μm) Image characteristics 30 Carrier development occurs 40 ５０ 50 ７０ 70 １００ 100 110 △ to １２０ 120 △ to △ 130 Fog occurrence / fading ( Occurrence)

[0019]

Table 2: Relationship between content of metal particles in developer and image characteristics Metal particle content (%) Image characteristics 1 Carrier development 2 ○ 3 ○ 6 ○ 15 ○ 20 ○ 23 Ground fog occurrence

[0020]

[Table 3]

[0021]

Table 4: Insulator content in metal particles Insulator content (%) Pattern specific resistance (Ω · cm) 4 3.0 × 10 ⁻⁶ (with conduction) 6 2.4 × 10 ⁻⁶ (With conduction) 8 1.7 × 10 ⁻⁶ (with conduction) 15 3.4 × 10 ⁻⁶ (with conduction) 20 1.7 × 10 ⁻⁴ (with conduction) 25 3.0 × 10 ⁶ (without conduction) )

[0022]

[Table 5] Table 5: Development Amount and Pattern Thickness / Resistivity at Development Sleeve Rotation Developing Sleeve Thickness after Development Pattern Thickness Pattern Specific Rotation (times) (μm) (μm) Resistance (Ω · cm) 0.8 16.5 11.0 3.0 × 10 ^-2 (without conduction) 1.0 20.8 15.5 1.7 × 10 ^-5 (with conduction) 1.5 26.4 21.1 2.0 × 10 ^-6 (with conduction) 2.0 29.0 24.2 2.4 × 10 ^-6 (with conduction) 3.0 35.5 28.4 3.4 × 10 ^-6 (with conduction) 5.0 50.0 38.0 5.0 × 10 ^-6 (with conduction) 5.5 52.0 39.2 (fog generation) 5.0 × 10 ^-6 (with conduction)

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an electrophotographic image forming apparatus used in the present invention.

[Explanation of symbols]

 Reference Signs List 11 photoconductor 13 charging member 15 image signal exposure member 17 developing member 19 transfer member 21 cleaning blade 23 entire surface exposure member

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshio Ozawa 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Office

Claims (8)

[Claims] An insulating surface-treated metal particle having a metal particle surface coated with a thermoplastic insulator to be insulated and having an average particle size in a range of 2 to 20 μm;
Insulating surface-treated metal particles are charged by the carrier particles using a developer consisting of μm carrier particles, and the electrostatic latent image formed on the photoreceptor is contact-developed by electrophotography, resulting in insulating surface treatment. An electrophotographic image forming method comprising forming a visible image from metal particles. 2. The electrophotograph according to claim 1, wherein the amount of the thermoplastic insulator in the insulated surface-treated metal particles is 20% by weight or less, and the resistance value of the particles is 10 ¹² Ω · cm or more. Image forming method. 3. The electrophotographic image forming method according to claim 1, wherein copper, tungsten, nickel or silver is used as the metal particles. 4. Insulated surface-treated metal particles obtained by polymerizing a monomer directly on the surface of a metal particle to form a coating made of a thermoplastic insulating material on the surface of the metal particle.
An electrophotographic image forming method according to any one of claims 1 to 3. 5. The electrophotographic image forming method according to claim 1, wherein an amorphous silicon photoconductor is used as the photoconductor. 6. The electrophotographic image forming method according to claim 1, wherein a layer thickness of a visible image formed from the insulated surface-treated metal particles is 20 to 50 μm. 7. A rotating photosensitive drum is used as the photosensitive member, and a developing sleeve rotating while holding a carrier magnetically is used as a developing means, wherein a rotating speed of the developing sleeve with respect to a rotating speed of the photosensitive drum is used. Linear speed ratio of 1.0
The electrophotographic image forming method according to any one of claims 1 to 6, wherein the development is performed at a setting of from 5.0 to 5.0. 8. A conductive pattern formed on a ceramic green sheet after transferring a visible image formed of the insulated surface-treated metal particles formed in any one of claims 1 to 7 onto a ceramic green sheet. A method for forming a conductive pattern on a ceramic substrate, comprising: forming a conductive pattern on a ceramic substrate;