JP2001317539A - Highly precise roller and image forming device having it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly precise roller capable of equalizing a charging amount, a developing electric field, or the like of toner existing on recessed and projecting parts on the surface of the roller, and suppressing and preventing problems of fog, a void, a ghost, or the like, and an image forming device having it. SOLUTION: This highly precise roller has a semi-conductive elastic body layer 2 around a conductive shaft body 1, and satisfies 50<Tp(50%)<100 when a load length ratio of the surface of the elastic body layer 2 is assumed to be Tp(C) (C is cutting level %).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-definition roll and an image forming apparatus provided with the same, and more particularly, to a photosensitive machine such as a copying machine, a laser beam printer (LBP), and a facsimile for forming an image by an electrophotographic system. The present invention relates to a high-definition roll optimally used as a charging roll, a developing roll, a transfer roll, and the like used around a drum, and an image forming apparatus including the same.

[0002]

2. Description of the Related Art In an electrostatic recording device employing a non-magnetic component contact developing method, specifically, a copying machine, a printer, a facsimile, etc., a toner is carried in a thin layer state on the surface of a developing roll in a developing process. The toner is brought into contact with a photosensitive drum having an electrostatic latent image, and the toner is transferred by Coulomb force under an appropriate developing bias to visualize the image. The developing roll is opposed to the photosensitive drum and functions to supply a necessary amount of toner having an appropriate charge amount. The toner is carried on the surface of the developing roll and is positively or negatively charged, but is mainly charged by friction with the toner supply roll and friction with the layer thickness regulating blade (frictional charging). Such a toner is required to be thinly and uniformly carried on the surface of the developing roll in a state of uniform charge amount in order to cope with the current high speed and high definition.

[0003] Generally, the characteristics of a developing roll are as follows.
It is defined by the thickness of the toner layer carried on the surface and the charge amount. Specifically, the toner charge amount per unit weight
(Q / M) and the toner weight per unit area (Q / A) are used. These conditions are determined by the device conditions such as the pressure of the layer thickness regulating blade, the shape and material of the toner supply roll, and the developing bias. If they are the same, it depends strongly on the physical shape (surface roughness), charging characteristics, friction coefficient, and resistance value of the outermost shell surface of the developing roll. How do you combine these factors,
The most important point in controlling the development of the developing roll is whether or not the developing property is controlled.

Conventionally, when controlling the above-mentioned surface roughness and friction coefficient, various shapes of organic and inorganic fillers are added in addition to polishing conditions for polishing the outermost layer of the developing roll. In addition, a quaternary ammonium salt or the like is added to control the charging characteristics, and a conductive agent such as carbon black or lithium perchlorate is added to control the surface resistance.

[0005]

The characteristics of the conventional developing roll are influenced by the above four factors. Among these, the surface roughness is particularly important because it greatly affects both the toner conveying force and the charge amount. Although the surface roughness of this developing roll is controlled by the polishing conditions at the time of polishing the outermost shell layer, the shape and amount of the filler to be added, the coating amount, the outermost shell layer coating, etc. Many of the parts have an acute angle. Such a shape
There is no problem when the toner layer is relatively thick, but when the toner layer is made thinner in order to improve the image quality and improve the development efficiency, the difference in the behavior of the toner in the concave and convex portions of the developing roll surface Is a problem.

That is, since the toner in the concave portion and the convex portion on the surface of the developing roll has a different spatial distance and a contact area with the opposing layer thickness regulating (or triboelectric) blade and the photosensitive drum, the stress received therefrom is different. This causes a difference in electric force, which causes non-uniformity in the toner charge amount and the developing electric field, thereby causing problems such as fog, white spots, and ghosts in the image. Especially for color,
Since a predetermined color is generated by superimposing Y (yellow), M (magenta), C (cyan), and B (black), if the behavior of the toner becomes unstable due to the above-mentioned causes, color unevenness and bleeding are likely to occur. . Such a phenomenon is caused when the surface roughness and the variation in the surface roughness are large, and the peak of the convex portion is sharper, in other words, the total contact area with the blade or the photosensitive drum is smaller and the point contact portion is larger. Is remarkable.

On the other hand, as an index representing the surface roughness, R
Although a (arithmetic average) and Rz (ten-point average) are generally used, they give a certain amount of knowledge about the height of the surface, but are extremely insufficient to grasp the shape. However, if the shape of the top of the convex portion cannot be grasped more accurately and the shape cannot be designed to meet the purpose, it is impossible to respond to the recent high definition of an image.

The present invention has been made in view of the above, and aims at equalizing the charge amount and the developing electric field of the toner on the concave and convex portions on the roll surface, and suppressing and preventing defects such as fog, white spots, and ghosts. It is an object of the present invention to provide a high-definition roll capable of performing the same and an image forming apparatus provided with the same.

[0009]

According to the first aspect of the present invention, in order to achieve the above object, a semiconductive elastic layer is formed around a conductive shaft body. When the load length ratio of the surface of the body layer is defined as Tp (C) (C: cutting level%), 50 <Tp (50%) <100 is satisfied. According to a second aspect of the invention, there is provided a high-definition roll according to the first aspect, in order to achieve the above object.

That is, in order to achieve the above object, the present inventors have found that the surface of a roll such as a developing roll has many surface contact portions in contact with a blade or a photosensitive drum.
The present inventors have found that it is sufficient to provide a roll surface shape that increases the total contact area, and completed the present invention. In order to impart such a surface shape, the surface of the roll is finely filled with a spherical filler on the surface of the elastic layer, the surface of the elastic layer is coated with a coating agent having a good leveling property, or the surface of the elastic layer is coated. In other words, a method of intentionally shaving off the top portion of the unevenness, in other words, the acute angle portion may be adopted. In particular, the last method is effective as a means for securing the toner conveying force due to the roughness and obtaining the surface shape of the roll having a large contact area with the blade or the photosensitive drum. In addition, by removing the acute angle portion by using these methods, it is possible to avoid a change in the development characteristics due to the removal of the apex of the convex portion during durability.

As an index representing the surface shape of the roll,
The optimum load length ratio is Tp (C) (C: cutting level%). Here, the load length ratio is, as shown in FIG. 1, a certain reference length L is extracted from the roughness curve of the roll surface, is parallel to the average line, and is below the highest peak by the cutting level C. The length of the cut portion of the surface cut along a straight line is expressed as a percentage of the total length L. The cutting level C according to the present invention is in accordance with the% method expressed as a percentage% when the highest peak is 0% and the lowest valley is 100%.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. A high-definition roll and an image forming apparatus provided with the same according to the present embodiment, as shown in FIG. The roll is composed of a conductive shaft 1 and a semiconductive elastic layer 2 formed on the outer periphery of the shaft 1, and the load length ratio of the surface of the elastic layer 2 is Tp (C). (C: cutting level%), 50 <Tp (50%) <100
To be satisfied. Then, such a high-definition roll is rotatably incorporated in the image forming apparatus of FIG. 3 and used as the charging roll 3, the developing roll 4, the transfer roll 5, and the like.

The shaft 1 is made conductive by mixing a shaft formed of a conductive metal such as iron, stainless steel, an aluminum alloy, or brass with a shaft molded of a thermoplastic resin or a thermosetting resin with a conductivity imparting agent. What is molded into a shaft with resin is used.

The composition of the elastic layer 2 is silicone rubber,
Polyurethane, chloroprene rubber, butyl rubber, polyisoprene rubber, polybutadiene rubber, nitrile rubber, styrene-butadiene rubber, ethylene-propylene rubber,
Ethylene-propylene-diene rubber, acrylic rubber, or a combination of two or more of natural rubber, if necessary, reinforcing silica filler such as fumed silica, precipitated silica, and conductive carbon black, nickel Metal powders such as aluminum, copper, etc., metal oxides such as zinc oxide and tin oxide, barium sulfate, titanium oxide, tin oxide, etc .; conductivity imparting agents such as potassium titanate; spherical silica, pulverized silica, silicone range A cross-linked polymethyl methacrylate, cross-linked polybutyl methacrylate, cross-linked polyacrylic acid ester, one or more selected from surface roughness imparting agents such as cross-linked acrylic particles are mixed at a predetermined ratio, peroxide, Vulcanizing agents and extenders necessary for vulcanization and curing of hydrogen siloxane, isocyanate, etc. in the presence of platinum catalyst Pressure to be produced. In mixing the above components, a known compound kneading method using a pressure kneader, a Banbury mixer, a mixing roll, a planetary mixer, or the like is employed.

The composition of the elastic layer 2 is crosslinked and vulcanized into a roll at the same time as the shaft 1 by a method such as extrusion molding, press molding, injection molding, or casting. If necessary, after molding, secondary vulcanization is performed for a certain period of time in a gear oven or the like. The surface of the vulcanized or secondary vulcanized composition of the elastic layer 2 is polished by a cylindrical grinder. When a coating is applied to the surface of the elastic layer 2,
In some cases, surface treatment is performed with a coupling agent or the like as a primer. This process may be performed by a normal method.
As the coupling agent, a silane coupling agent, a titanate coupling agent, or the like is used. These coupling agents are diluted with a solvent at a ratio specified by the manufacturer and applied.

The means for surface coating is not particularly limited, but a method of applying a resin in a solution state is generally used. When applying the resin, a general-purpose coating machine such as a roll coater, a gravure coater, or a spray coater may be used, or a dipping method in which the resin is directly immersed in a resin solution may be employed. However, the method of forming the resin layer is not limited to these. In short, it is sufficient that the resin component can be applied to the surface of the elastic layer 2. For example, the resin may be formed into a cylindrical shape in advance by an extrusion molding method or a press molding method, and then press-fitted into the elastic layer 2. .

As the resin used for the surface coating,
Examples include urethane resins, fluorine resins, acrylic resins, silicone resins, silicone-urethane resins, acryl-urethane resins, polyamide resins, alkyd resins, epoxy resins, phenolic resins, and mixtures thereof. For the crosslinking, an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, a hydrogen siloxane compound or the like is used. These resins are not used singly, but may be used as a mixture of several types.To add surface roughness, spherical silica, pulverized silica, silicone resin, cross-linked polymethyl methacrylate, cross-linked polymethacrylic acid It is possible to mix and use fillers such as butyl, crosslinked polyacrylate, crosslinked acrylic particles and the like.

As a method of forming the top of the convex portion on the surface of the elastic layer 2 into a smooth surface, a spherical filler such as silica is finely filled in the surface of the elastic layer 2 or the surface is excellent in leveling property. A method of applying a coating agent and the like can be mentioned. However, if the surface of the elastic layer 2 is polished again with a film having a number of about 2,000 to 4,000 after finish polishing and surface coating, the conditions of the present invention can be relatively easily satisfied. According to this method, the top of the convex portion on the surface of the elastic layer 2 is intentionally scraped off. However, the shape of the filler, the wettability, the particle size distribution, the coating type,
Since variations in surface roughness due to coating conditions can be absorbed, there is an advantage that both good images and stable processes can be satisfied.

[0019]

EXAMPLES Examples of the high-definition roll according to the present invention will be described below together with comparative examples. Example 1 First, a mixture of silicone-based primers No. 23 and No. 4 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) at a ratio of 1: 1 was applied to a shaft that is a conductive shaft 1, and the mixture was placed in a gear oven. At 150 ° C. for 10 minutes. The shaft has a size of 10 mm in diameter and 400 mm in length by electroless nickel plating on the SUM 22.

As a conductive silicone rubber composition, an organic peroxide-reactive silicone raw rubber, KE-78VB
S [Shin-Etsu Chemical Co., Ltd. product name] 100 parts by weight, carbon black thermal black [Asahi Carbon Co., Ltd. product name] 10 parts by weight, fumed silica-based filler Aerosil 200 [Nippon Aerosil Co., Ltd. [Product name] 25 parts by weight, kneaded with a pressure kneader, and further added 2.0 parts by weight of organic peroxide-based vulcanizing agent C-8 [Shin-Etsu Chemical Co., Ltd. product name] Got ready. This was vulcanized and bonded to the shaft body 1 at 175 ° C. for 10 minutes using a compression mold having a cylindrical cavity with an inner diameter of 20 mm, and subjected to secondary vulcanization in a gear oven at 200 ° C. for 7 hours. Then, it was polished with a cylindrical grinder to produce a roll-shaped molded article having a diameter of 18 mm and a rubber part length of 320 mm provided with a solid elastic layer 2 around the shaft 1.

As the resin layer, urethane paint Nipporan 3
022, curing agent Coronate L (both trade names manufactured by Nippon Polyurethane Co., Ltd.), spherical silicone resin KMP-
590 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) to 100:
A paint was prepared by blending at 5:16, and applied to a surface of a roll-shaped molded product coated with Primer C (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) to a film thickness of 15 μm using a spray coater. After that, the roll was dried and cured at 140 ° C. for 30 minutes in a gear oven to produce a high-definition roll according to the present invention. The following measurement items were tested, and the results were summarized in Table 1 and evaluated. .

Measurement Items (1) Load Length Rate Tp (C) The load length rate Tp (50%) of the roll surface was measured using Surfcom 590A manufactured by Tokyo Seimitsu Co., Ltd. This measurement was performed five times at different points. Then, evaluation was performed using the average value, and those satisfying 50 <Tp (50%) <100 were regarded as acceptable. (2) Fog A continuous printing test with an electrophotographic printer showed that
Repeat halftone, 5% duty, white printing, etc. 5%
The Macbeth density on a white background portion of the duty image was measured using a Macbeth densitometer. Those having a measured value of 0.015 or less were regarded as acceptable.

Example 2 The spherical spherical dry silica of Example 1 was crushed into silica NIPGEL.
AZ-200 (trade name of Nippon Silica Co., Ltd.), and the roll surface after coating was polished with a Noritake film (trade name: MAXIMA CG # 4000). Otherwise, a high-definition roll according to the present invention was produced in the same manner as in Example 1, and a test was carried out for the above-mentioned measurement items. Example 3 In Example 1, the coating was not performed, and the surface of the roll was coated with a film made of Noritake [trade name: MAXIMA CG # 4]
000]. Otherwise, a high-definition roll according to the present invention was produced in the same manner as in Example 1, and a test was carried out for the above-mentioned measurement items.

Comparative Example 1 The spherical silicone resin KMP-590 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) of Example 1 was crushed with silica NIPGE.
LAZ-200 (trade name, manufactured by Nippon Silica Co., Ltd.). Except for this, a high-definition roll was produced in the same manner as in Example 1, and tests were carried out on the above measurement items. Table 1 summarizes the results. As a result of the evaluation, unlike Examples 1, 2, and 3, both the load length ratio Tp (50%) and fog were rejected. Comparative Example 2 A high-definition roll was prepared in the same manner as in Example 1 except that the coating was not performed, and a test was carried out for the above measurement items. Table 1 summarizes the results. As a result of the evaluation, unlike Examples 1, 2, and 3, both the load length ratio Tp (50%) and fog were rejected.

[0025]

[Table 1]

[0026]

As described above, according to the present invention, the charge amount and the developing electric field of the toner on the concave and convex portions of the roll surface are made uniform, and problems such as fog, white spots, and ghosts are suppressed. There is an effect that it can be prevented. When the high-definition roll according to the present invention is used in an image forming apparatus, a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph illustrating a load length ratio of a high-definition roll according to the present invention.

FIG. 2 is a perspective explanatory view showing an embodiment of a high-definition roll according to the present invention.

FIG. 3 is an explanatory sectional view showing an embodiment of an image forming apparatus provided with a high-definition roll according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft 2 Elastic layer 3 Charging roll 4 Developing roll 5 Transfer roll

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G03G 15/16 103 G03G 15/16 103 F term (reference) 2H003 BB11 CC05 2H032 AA05 BA19 BA23 2H077 AD06 FA01 FA13 FA22 FA25 3J103 AA02 AA13 AA14 AA72 BA41 EA02 EA20 FA30 GA02 GA57 GA58 GA60 GA74 HA03 HA04 HA05 HA12 HA20 HA22 HA32 HA33 HA36 HA37 HA41 HA43 HA47 HA48 HA53 HA54

Claims (2)

[Claims] 1. A high-definition roll in which a semiconductive elastic layer is formed around a conductive shaft body, wherein the load length ratio of the surface of the elastic layer is Tp (C) (C: cutting A high-definition roll characterized by satisfying 50 <Tp (50%) <100, when (% level). 2. An image forming apparatus comprising the high-definition roll according to claim 1.