JP3477063B2 - Electrophotographic image forming method - Google Patents

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 obtained by surface-treating metal particles to insulate them. Used for.

[0002]

2. Description of the Related Art Conventionally, in the formation of a conductor pattern such as an electrode of a ceramic multilayer capacitor or the like, a metal such as copper or tungsten is placed on a thin green sheet made of ceramic powder such as silica / alumina and an organic binder. An electrode pattern was formed by forming a paste of particles in a pattern by screen printing and firing the paste.
However, since this method uses a screen composed of a mesh net, the printing accuracy decreases due to screen sagging after endurance, material loss for creating the screen for each pattern, and material loss that adheres to the mesh. There was a problem of causing.

In order to solve the above-mentioned drawbacks, JP-A-59-59
No. 189617, No. 59-202682, No. 60-137886, No. 60-160690 and the like describe that an electrode pattern of conductive particles is formed by an electrophotographic method, and the pattern is baked. There is.
Specifically, for example, tungsten powder and styrene acrylic resin are kneaded, pulverized, and classified to obtain particles for printing (toner) having a particle size of 10 to 20 μm. An electrode pattern is formed. However, since the printing particles in these methods have low resistance and easily leak electric charges, it has been difficult to reproduce a highly accurate pattern in an electrophotographic apparatus, and it is difficult to form a reliable conductive path.

[0004]

In the above-mentioned conventional printing particles, the composition of the particles has not yet formed high resistance particles, and the charging becomes non-uniform. That is, when a sufficient amount of metal powder to form a conductive path after firing is mixed in the particles, the amount of resin is relatively decreased, the amount of metal powder exposed on the surface of the particles is increased, and the resistance of the particles is lowered. On the other hand, when the amount of resin is increased to increase the resistance, the amount of metal particles is decreased, and it becomes difficult to create the conductive path, which is the original purpose. Therefore, in the conventional method using printing particles, it is difficult to form an image by the electrophotographic method in which the particles are controlled as charged particles. Therefore, it is an object of the present invention to form a conductor pattern with higher accuracy and higher reliability as compared with a system using a conventional electrophotographic method.

[0005]

Electrophotographic image forming method of the present invention, in order to solve the problem] is the coating obtained by polymerizing a direct mode Nomar a metal particle surface of a thermoplastic insulator, it said thermoplastic insulating material occupying in grains Is less than 20% by weight, and the particle resistance value is 1
0 12 ohms · cm or more, and a surface-treated metal particles having an average particle size in the range of 2 to 20 [mu] m, an average particle diameter 40~120μ
The carrier particles are used to charge the surface-treated metal particles, and the electrostatic latent image formed on the photoreceptor by electrophotography is contact-developed. It is characterized by forming a visible image.
The surface-treated metal particles used in the present invention can enclose a large amount of metal particles, and since the surface is firmly covered with the thermoplastic resin, the particles are an insulator, and the particles are stably uniformly charged and have a uniform charge. There is no leak. 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 formed by coating the surfaces of the metal particles with a thermoplastic insulator. As the metal particles, any may be used,
Copper, tungsten, nickel, silver, etc. are used when printing a conductor pattern on a ceramic green sheet. The selection of the metal is determined by the 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 it is alumina, tungsten is suitable. Various synthetic resins are used as the thermoplastic insulator. When it is assumed that the conductor pattern is printed on the ceramic green sheet, the ceramic green sheet needs to be erased 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 coat the surface of the metal particles without substantially exposing the surface of the metal particles, and this method can be realized by a small amount of thermoplastic insulator. Is preferred. As this method, for example, there is a method in which a monomer is directly polymerized on the surface of metal particles to form a thermoplastic resin layer. Specifically, for example, a catalyst is adsorbed on the surface of metal particles, ethylene gas or the like is supplied, and this monomer gas is directly polymerized on the surface of the metal particles to form a polyethylene resin film. Although this method is a method for producing carrier particles, it is disclosed in JP-A 2-1.
It is described in detail in No. 87770, No. 2-187771, etc., and can be directly applied to the production of the insulated surface-treated metal particles of the present invention.

In the present invention, the insulating surface-treated metal particles have an average particle size of 2 to 20 μm, preferably 3 to 10 μm. If this average particle size is too large or too small, electrostatic control becomes difficult, and fog on the ground occurs and the image level decreases. If 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 mainly controlled by electrostatic force, so that it is required to be stably and uniformly charged. Therefore, the insulated surface-treated metal particles of the present invention are required to be an insulator, 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, background fog and transfer failure are likely to occur. Further, it is conceivable to increase the total amount of the insulating material in order to increase the insulating property. However, if it is increased too much, the amount of the conductive material after firing decreases, and it becomes difficult to obtain conduction of the conductive pattern. Generally, the thickness of the conductive path on the pattern needs to be 15 μm or more. Considering the difference in specific gravity between the metal and the insulating material, the packing rate of particles on the sheet after transfer, the amount of particles that can be controlled by an electrophotographic technique, etc. The amount of the insulating material in the insulated surface-treated metal particles is preferably 20% by weight or less, more preferably 15% by weight or less. In order to secure the pattern thickness of 15 μm or more after firing, the layer thickness of the insulating surface-treated metal particles (toner particles) formed after development is preferably 20 to 50 μm, and preferably 25 to 50 μm.
μm. If this layer is too thick, problems such as bleeding will 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 by a two-component developing method is applied. In this case, the particle size of the carrier is preferably 40 to 120 μm, more preferably 40 to 100 μm. If the particle size of the carrier becomes too small, the carrier is also developed, while
If it becomes too large, the electrostatic charge on the particles is reduced, causing fog on the ground. 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 2 to 20% by weight, more preferably 3 to 10% by weight. If the content is less than 2% by weight, even 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 no different from a general apparatus. That is, the drum-shaped photosensitive member 11 of amorphous silicon type or the like
The charging member 13, the image signal exposing member 15, the developing member 17, the transfer member 19, and the cleaning blade 2 around the
1. The whole surface exposure member 23 is provided. By using an amorphous silicon-based photoconductor with excellent printing durability,
An apparatus is provided that facilitates maintenance and reduces material loss. In the present invention, the 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 exposing member 15 on the photoconductor 11 uniformly charged in the dark by the charging member 13, and the electrostatic latent image of the conductor pattern is contact-developed by the developing member 17 so that the electrostatic surface-treated metal particles A toner image (visual image) is formed on the surface of the photoconductor 11. The linear velocity between the rotational speed of the drum-shaped photoconductor 11 and the rotational speed of the developing member 17 and the developing sleeve is 1.0 to 5.0, and preferably 1.5 to 5.0. If the rotation speed of the developing sleeve is too low, the amount of development will be insufficient, while if it is too large, bleeding will occur.

Next, a thin sheet (green sheet) made of 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 transcribed. In the present invention, the insulating surface-treated metal particles used as the toner have high resistance and can be uniformly and stably charged, so that the development process and the transfer process can be easily controlled, and a highly accurate pattern can be formed on the green sheet. printing,
Can be formed. The members around the photoconductor 11 in FIG. 1 can be changed in various ways. For example, as the charging member 13, a conductive brush or a conductive roller can be used instead of the corona charging device.

The green sheet on which the pattern is formed is
A conductor pattern is obtained by heating at an appropriate temperature, for example, 800 ° C. or higher and firing to eliminate the insulator. The insulated surface-treated metal particles of the present invention have a high resistance value and can be uniformly charged, but since the metal particles occupy many portions,
After firing, a conductive pattern having good continuity and high reliability can be obtained. By utilizing the fact that the insulator of the insulated surface-treated metal particles is thermoplastic, appropriate heat (for example, 200 ° C. or less) is applied between the formation of the pattern on the green sheet and the firing. Hypothetical attachment can be performed, or an adhesive can be sprayed onto the pattern on the green sheet and temporarily fixed.

[0013]

According to the electrophotographic image forming method of the present invention, by using the insulating surface-treated metal particles having both a large metal particle ratio and a high insulating property, it is possible to uniformly charge due to the high insulating property. As a result, a conductor pattern can be printed and formed on the green sheet with high accuracy, and a conductor pattern having good continuity and high reliability after firing can be formed.

[0014]

EXAMPLE Using the electrophotographic image forming apparatus shown in FIG.
A conductor pattern was printed on the ceramic green sheet. Here, as the photosensitive member, an amorphous silicon photosensitive member having a photosensitive layer thickness of 25 μm was used. The insulating surface-treated metal particles used as a toner are obtained by directly polymerizing ethylene monomer on copper powder and coating the copper powder with a polyethylene resin in a weight ratio of 6% by weight, and then adding silica to particles having an average particle size of 6 μm. Externally added toner particles (metal particles) were used. An image of a conductor pattern was formed by using a carrier composed of ferrite particles having an average particle diameter of 70 μm and incorporating the toner particles (metal particles) in a content ratio of 8% by weight to prepare a developer. The image forming conditions were set as follows. Photoconductor charge potential: 350V After exposure After exposure: 15V Current image potential: 120V Photoconductor drum linear velocity: 60mm / sec Current image linear velocity: 120mm / sec Development sleeve rotation speed (linear velocity ratio to the rotation speed of the photoconductor drum) : 2.0 times

A conductive pattern formed by electrophotography is formed on a green sheet containing silica as a main component, which is then sintered in a reducing atmosphere at 900 ° C. for 1 hour to form copper on a ceramic substrate. A conductor pattern was formed. Under the above conditions, the following experiments were conducted as a base to confirm the influence of each condition parameter. (1) Carrier particle size The image characteristics were evaluated by changing the carrier particle size in the range of 30 to 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 in the range of 40 to 120 μm, especially 40 to 100 μm. (2) Metal particle (toner particle) content rate in the developer The metal particle (toner particle) content rate in the developer is 1 to
The image characteristics were evaluated by changing within the range of 23% by weight, and the results are shown in Table 2. Metal particle content is 2 to 20% by weight
A good pattern was formed.

(3) Resistance value of metal particles By adjusting the thickness of the polyethylene resin layer formed on the metal particles, the resistance of the insulating surface-treated metal particles (toner particles) is changed to evaluate the image characteristics. The results are shown in Table 3. It can be seen that an excellent pattern image is formed by setting the resistance value to 10 ¹² Ω or more. (4) Content of Insulator in Metal Particles Formed after firing by controlling the amount of insulator contained in the insulating surface-treated metal particles (toner particles) in which the amount of polyethylene resin formed on the metal particles is adjusted. 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 insulating material content to 20% by weight or less, stable conduction after firing can be obtained.

(5) Number of revolutions of developing sleeve The number of revolutions of the developing sleeve with respect to the photosensitive drum is changed to form toner images of various thicknesses (thickness after development), and the pattern thickness and pattern specific resistance after firing are evaluated. The results are shown in Table 5. A good pattern was obtained when the number of rotations of the developing sleeve was 1.0 to 5.0 times the linear velocity ratio with respect to the number of rotations of the photosensitive drum. At this time, the film thickness of the developer after development is 20 to 50 μm, and when this is baked, the thickness is 1
A pattern of 5 to 38 μm was formed, and stable conduction was obtained.

[0018]

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

[0019]

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

[0020]

[Table 3]

[0021]

[Table 4] Table 4: Insulator content rate in metal particles Insulator content rate (%) Pattern specific resistance (Ω · cm) 4 3.0 × 10 ⁻⁶ (with conduction) 6 2.4 × 10 ⁻⁶ (Conducted) 8 1.7 × 10 ^-6 (Conducted) 15 3.4 × 10 ^-6 (Conducted) 20 1.7 × 10 ^-4 (Conducted) 25 3.0 × 10 ⁶ (No conduction) )

[0022]

[Table 5] Table 5: Development amount at development sleeve rotation speed and pattern thickness / specific resistance Development sleeve Thickness after development Pattern thickness Pattern specific rotation speed (times) (μm) (μm) Resistance (Ω · cm) 0.8 16.5 11.0 3.0 × 10 ^-2 (without continuity) 1.0 20.8 15.5 1.7 × 10 ^-5 (with continuity) 1.5 26.4 21.1 2.0 × 10 ^-6 (with continuity) 2.0 29.0 24.2 2.4 × 10 ^-6 (with continuity) 3.0 35.5 28.4 3.4 × 10 ^-6 (Continuous) 5.0 50.0 38.0 5.0 × 10 ^-6 (Continuous) 5.5 52.0 39.2 (Fog occurs) 5.0 × 10 ^-6 (Continuous)

[Brief description of drawings]

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

[Explanation of symbols]

11 photoconductor 13 Charging member 15 Image signal exposure member 17 Developing member 19 Transfer member 21 cleaning blade 23 Full surface exposure member

Continuation of the front page (56) Reference JP 60-127787 (JP, A) JP 59-191395 (JP, A) JP 59-123848 (JP, A) JP 59-40597 (JP , A) JP 56-167388 (JP, A) JP 9-281806 (JP, A) JP 7-263841 (JP, A) JP 6-51628 (JP, A) JP 4-237062 (JP, A) JP-A-4-78191 (JP, A) JP-A-4-70850 (JP, A) JP-A-2-187771 (JP, A) JP-A-2-187770 (JP, A) A) HYBRIDS, 1992, VOL. 8, No. 5 (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (5)

(57) [Claims] 1. A method of directly polymerizing a monomer on the surface of a metal particle
The thermoplastic insulating material is coated , the content of the thermoplastic insulating material in the particles is 20% by weight or less, the resistance value of the particles is 10 12 Ω · cm or more, and the average particle diameter is 2 to 20 μm.
Surface-treated metal particles having an average particle size of 40 to 12
Using a developer composed of 0 μm carrier particles, the surface-treated metal particles are charged with the carrier particles, and the electrostatic latent image formed on the photoreceptor by electrophotography is contact-developed,
An electrophotographic image forming method comprising forming a visible image from surface-treated metal particles. 2. The electrophotographic image forming method according to claim 1, wherein copper, tungsten, nickel or silver is used as the metal particles. As 3. A photoconductor, electrophotographic imaging process according to any one of claims 1-2 using an amorphous silicon photosensitive member. 4. An electrophotographic imaging process according to any one of claims 1 to 3 the layer thickness of the visible image is 20~50μm formed from the surface-treated metal particles. 5. A photosensitive drum that rotates is used as the photosensitive member, and a developing sleeve that magnetically holds a carrier to rotate is used as a developing unit, and the rotational speed of the developing sleeve relative to the rotational speed of the photosensitive drum is changed. Linear velocity ratio is 1.0
An image forming process according to any one of claims 1-4 for developing is set to 5.0.