JP2000112230A - Developing blade for electrophotographic device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high-quality images without irregularity in images or stripes and to obtain stable blade characteristics and triboelectric charge characteristics by forming this device in a multi-layered structure in which a coating layer having uniform film thickness is provided with a polyurethane elastomer having excellent wear resistance on the surface of a rubber elastic member made of silicone rubber having a short molding cycle and good fluidity of a material and making the structure of a pressing face convex face. SOLUTION: A rubber elastic body 2 having a semi-circular convex face is fixed to a spring metal thin plate 1, and further, an elastic coating layer 3 is provided on the surface of the rubber elastic body 2 to make it a multilayered rubber elastic body. The rubber elastic body 2 is fixed into one body with the metal thin plate 1 by chemical adhesion with an adhesive or by physical adhesion by biting on the metal thin plate. The metal thin plate 1 is preferably copper or a copper alloy or a steel material such as stainless steel having corrosion resistance. The hardness of the rubber elastic body 2 is properly selected from a range of 20 to 90 in the JIS-A type, more preferably 30 to 80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller used in a developing section in a printing apparatus using an electrophotographic system and a developing blade used in pressure contact with the developing roller.

[0002]

2. Description of the Related Art A developing blade used in a developing section of an electrophotographic printing apparatus such as a copying machine or a laser beam printer removes toner particles excessively adhering to a developing roller to make the adhering amount uniform. It works.

[0003] In a conventional early developing blade, a flat elastic body was integrally formed on a metal plate as shown in FIG.
Therefore, at the time of press contact, the elastic plate comes into contact with the outer periphery of the developing roller in a shape, and the contact portion is planar (FIG. 5).

[0004] Thereafter, as the toner particles are made finer and the printing resolution is improved, it is necessary to make the toner particles adhere to the developing roller thinly and uniformly, and the developing blade is required to be uniformly pressed against the developing roller. In the initial surface contact, uniform pressure contact with the developing roller in the axial direction is difficult, and the amount of toner particles attached tends to vary, and there is a limit to the adjustment of the charge imparting property and the thickness of the toner particles. Image defects such as streaks have come to be detected.

Therefore, in recent years, as shown in FIG. 6, a developing blade is integrally formed with a rubber-like elastic body having a convex curved surface on a long thin metal plate having a spring property, and the convex curved portion is pressed against the outer periphery of the developing roller. Attempts have been made to create a line contact with the developing roller, to make the toner particles adhere thinly and more uniformly by a uniform pressing force, thereby obtaining an image with uniform charge imparting property, image unevenness and no streaks. I have.

The rubber-like elastic material of the developing blade is required to have abrasion resistance, hydrolysis resistance, ozone resistance, low distortion, triboelectric charging, toner resistance, surface smoothness, and the like. Liquid or millable polyurethane elastomers are used.

[0007]

However, conventionally used rubber-like elastic polyurethane elastomers are liquid-type polyurethane elastomers, which are expensive in material, have a long molding cycle, and are expensive. In such a case, the fluidity of the material is poor and it is difficult to form the material into a desired shape or surface state, and there is a problem that a desired line contact cannot be obtained.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has abrasion resistance, hydrolysis resistance, ozone resistance, low distortion, triboelectric charging, toner resistance, and surface smoothness. An object of the present invention is to provide a developing blade for an electrophotographic apparatus, which satisfies all of the above requirements and is low in cost and excellent in productivity.

Therefore, in the present invention, the rubber-like elastic portion of the developing blade is formed of a low-cost rubber-like elastic material, and a coating layer having necessary characteristics is provided on the surface.
That is, the developing blade for electrophotography according to the present invention forms a convex curved surface with a rubber-like elastic material having a short molding cycle and good material flowability on a springy metal sheet, and the rubber-like elastic body portion Characterized in that a multi-layer structure is provided by providing an elastic coating layer having a uniform film thickness with excellent wear resistance on the surface of the film.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the springy metal sheet used for the developing blade of the present invention, steel materials such as copper and copper alloys and stainless steel having corrosion resistance are preferable. This production is not particularly limited, for example, a method of improving performance by quenching and tempering after hot working, a method of giving desired properties by cold working, and a method of using heat treatment in combination with cold working. The thickness of the metal sheet is preferably 0.05 to 0.30 mm, which is suitable for etching or punching with a press.

The rubber-like elastic body used in the present invention is:
It is a rubber-like elastic body, and its hardness is preferably appropriately selected from the range of 20 to 90 in the JIS-A type, and more preferably 30 to 8 in order to match the design and pressing force of the equipment.
A range of 0 is desirable. Further, as the raw material, a material having a low molecular weight or a material having low plasticity at the time of molding is preferable in consideration of moldability and material fluidity, and examples thereof include a liquid polymer, silicone rubber, and a thermoplastic elastomer. Above all, the vulcanization time is short, the characteristics are not affected by the environmental temperature,
Silicone rubber having excellent weather resistance and high rebound resilience is desirable. The surface of the rubber-like elastic portion had a multilayer structure in which a polyurethane elastomer coating layer was formed to obtain abrasion resistance and charging characteristics.

[0012] The hardness of polyurethane elastomer is JIS
-A type 60 or more is preferable, and if the JIS-A hardness is less than 60, the wear resistance is extremely poor because of softness. The thickness of the coating layer is preferably 5 μm or more, and characteristics such as abrasion resistance, hydrolysis resistance, ozone resistance, low distortion, triboelectric charging, toner resistance, and surface smoothness can be obtained. Considering the mass production stability of the coating layer with uniform thickness,
A range of 50 μm is preferred.

[0013] In the production method of the present invention, when silicone rubber is used for the rubber-like elastic body, after molding the silicone rubber,
The surface of the silicone rubber is surface-modified by a short-wavelength ultraviolet irradiation treatment, a plasma discharge treatment, a flame treatment method or the like, and a coating layer made of a polyurethane elastomer is applied to the surface-modified portion. If the polyurethane elastomer is coated directly on the silicone rubber, the adhesion as a blade body cannot be obtained, and the polyurethane elastomer layer is peeled off by friction with the developing roller, which is not preferable. This problem could be avoided by surface modification. Examples of the method of applying the coating material include a method of applying a polyurethane elastomer diluted with a liquid type or a solvent by painting or dipping.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a developing blade for an electrophotographic apparatus according to the present invention has a rubber-like elastic body 2 having a semicylindrical convex curved surface fixed to a springy metal thin plate 1.
Is provided with an elastic coating layer 3 on the surface thereof to form a rubber elastic body having a multilayer structure. The rubber-like elastic body 2 is integrally fixed to the metal sheet 1 by chemical bonding with an adhesive or physical bonding by biting to the metal sheet. Integral molding is
A method in which a thin metal plate coated with an adhesive is positioned in a mold having a cavity for an elastic body cut into a shape similar to that shown in FIG. 2, a method in which a biting hole or the like is previously formed in a thin metal plate and a rubber-like elastic body is integrally formed can be used.

SUS304-CSP H,
The material having a thickness of 0.15 mm was processed into a shape that can be attached to the printer cartridge by etching. A silicone rubber adhesive primer (manufactured by Toray Dow Corning, SH2260) was applied to one end of the metal sheet. As the silicone rubber, a general-purpose type millable silicone rubber hardness JIS-A60 (manufactured by Tore Dow Corning, SH861U) was used. The metal sheet subjected to the bonding process is positioned and fixed in a transfer die cut into a shape having a curved surface, and silicone rubber is caused to flow from an injection gate. Molding at 165 ° C is 5
The mixture was subjected to pressure hardening for 5 minutes to produce a blade member.

The surface of the blade member thus produced is irradiated with a short-wavelength ultraviolet ray, and the surface of the treated silicone rubber is coated with 100 parts by weight of polyol and 25 parts of isocyanate.
Polyurethane elastomer paint composed of a blended material of 12 parts by weight of silica and 12 parts by weight of silica (JIS-
(AHs = 97) was coated by a spray method and dried and solidified at 150 ° C. for 30 minutes in a drying oven.

As Comparative Example 1, a rubber-like elastic body was made of a millable urethane rubber material, and as Comparative Example 2, a silicone rubber material was produced. In addition, the measurement of the amount of wear described in Table 1 was performed using a grinding wheel H-
22, measured at a load of 1 kgf × 2 and a number of rotations of 1,000. [Table 1] Example 1 Comparative Example 1 Comparative Example 2 Abrasion amount (mg) 20 45 2,000 Toner fixed Non-fixed Non-fixed Non-fixed Productivity (1 mold surface) 60 pieces / h 42 pieces / h 60 pieces / h

Further, as Embodiments 2 and 3,
The surface of the silicone rubber treated with the plasma discharge of the blade member was coated with about 1.5% of the polyurethane elastomer of the above formulation.
A rubber-like elastic material was manufactured by drying and solidifying each of those immersed once and twice in the double-diluted solution for about 10 seconds at 150 ° C. for 30 minutes in a drying furnace.

Further, as comparative examples, those having a thin coating film were produced as Comparative Example 3, and those having a large coating film were produced as Comparative Examples 4 and 5. In these Examples and Comparative Examples, the image and the surface state of the coating layer in the actual machine were determined, and the results are shown in Table 3. The coating thickness was measured using a projector by cutting the blade member at equal intervals at five locations in the longitudinal direction. The image unevenness in the actual machine was determined by visually observing a solid image printed with a blade member attached to a developing unit of a printer (Phaser560PJ, manufactured by Sony Tektronix), and the results are shown in Table 2. [Table 2] Example (comparative example) 1 2 3 (3) (4) (5) Film thickness 8 to 12 μm 20 to 24 μm 42 to 48 μm 2 to 4 μm 50 to 60 μm 5 5 to 68 μm Solvent dilution 2 times 1 1.5 times 1.5 times 3 times 2 times-Coating method Coating Technics Coating Coating Coatings Technick Number of application times 1 1 2 1 5 1 (Yes) (Repelling the membrane)

[0020]

The developing blade for electrophotography of the present invention has a uniform molding thickness on the surface of the rubber-like elastic portion of silicone rubber having a short molding cycle and good fluidity, and a polyurethane elastomer having excellent wear resistance. With a multilayer structure provided with a coating layer, and the shape of the pressure contact surface is a convex curved surface, the contact with the developing roller becomes linear at the time of pressure contact, and the toner particles are thinly adhered by uniform pressure, and thereby uniform. In addition to the effect of providing charge imparting properties and realizing high quality images without image unevenness and streaks, it is easy to process and has long-term stable blade characteristics, triboelectric charging characteristics, low cost and excellent productivity. became.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view showing a contact state between a developing blade and a developing roller according to the embodiment of the present invention.

FIG. 3 is a sectional view of an embodiment of the present invention.

FIG. 4 is a cross-sectional view of the prior art.

FIG. 5 is a cross-sectional view of a conventional contact state between a developing blade and a developing roller.

FIG. 6 is a cross-sectional view showing a contact state between another conventional developing blade and a developing roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal thin plate 2 Rubbery elastic body 3 Coating layer 4 Convex curved surface

Claims (4)

[Claims] 1. An electrophotographic apparatus characterized by comprising a multi-layer rubber-like elastic body in which a rubber-like elastic body having a convex curved surface is provided with an elastic coating layer on a thin metal plate having a spring property. Development blade. 2. The developing blade according to claim 1, wherein the elastic coating layer is made of a polyurethane elastomer. 3. The developing blade for an electrophotographic apparatus according to claim 1, wherein the rubber-like elastic body is made of silicone rubber. 4. After an elastic body made of silicone rubber is integrally formed on a springy metal thin plate, the surface of the elastic body is subjected to at least one treatment selected from a short-wavelength ultraviolet irradiation treatment, a plasma discharge treatment, and a flame treatment. A method for producing a developing blade for an electrophotographic apparatus, wherein the surface is modified by a method, and a coating material comprising a polyurethane elastomer is applied to the surface-modified portion.