JP2001323925A - Semi-conductive roll and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing roll such as an electrophotographic printer hardly causing the printing failure due to a negative afterimage and a positive afterimage, and to provide a developing device using the same. SOLUTION: The relation among the mean roughness Rz of ten points in the surface of semi-conductive rolls 10 and 20 to be used for developing roll, a mean space Sm of projecting parts and recessed parts, and a coefficient of the dynamic friction μ satisfies a formula, 0.1<=(1/Sm)×((Sm/2)2+(Rz)2)1/2×μ<=1.0, (Sm=10-200×10-6m, Rz=1-20×10-6m, μ=0.1-1.2). The developing roll of a developing device is formed of a semi-conductive roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a toner carrier layer having a conductor and an elastic semiconductive layer located outside the toner carrier, and is supported in a thin layer on the outer periphery of the carrier. The present invention relates to a semiconductive roll used as a developing roll in a developing device for visualizing an electrostatic latent image formed on a latent image carrier by frictionally charged toner, and a developing device using the same.

[0002]

2. Description of the Related Art A toner carrier layer having an electric conductor and an elastic semiconductive layer located outside thereof is provided, and a triboelectrically charged toner carried in a thin layer on the outer periphery of the carrier is provided by:
In a developing device such as an electrophotographic system for visualizing an electrostatic latent image formed on a latent image carrier, a conductive, environmental resistance, and low hardness are used for a semiconductive roll used as a developing roll. , Triboelectric charging characteristics, toner transportability and the like are required.

In response to such demands, urethane rubber,
Rolls made of NBR, silicone rubber or the like and made semiconductive by adding an ion conductive substance or an electron conductive substance as a conductivity imparting agent are well known. When controlling the conductivity, a compound such as a resin or a rubber filled with carbon black, conductive metal particles, metal oxide particles and the like is used as the conductivity imparting agent.

[0004] These rolls are required to have initial printing characteristics and aging printing characteristics in addition to mechanical characteristics. The print characteristics include, in particular, the level of an afterimage as an independence with respect to the print history, in addition to the print density due to the toner transportability, the fog and fine line reproducibility due to the toner charging characteristics, and the like.

[0005]

In the conventional semiconductive roll, for example, if the ten-point average roughness Rz of the surface of the elastic material according to the JIS system is increased, the toner transportability is improved, but the fog tends to increase. At the same time, there is a problem that the graininess tends to decrease. Therefore, Rz
Although a method of controlling the friction coefficient of the surface instead of increasing the friction coefficient has been proposed, if the friction coefficient is too low, the toner transportability is insufficient, the density becomes insufficient, and if the friction coefficient is too high, Since the charging of the toner cannot be increased to a sufficient level, there has been a problem that fog tends to increase. At the same time, the frictional energy applied to the toner is large, and the toner is likely to be deteriorated.

[0006] Further, as the quality of printed images has been improved,
Image density unevenness called image retention caused by printing history (image density decreases (hereinafter referred to as negative image retention) or increases (hereinafter referred to as positive image retention) in the print portion of the second and subsequent rotations of the portion printed by the roller in the first rotation. ) Is more problematic than in the past.

The object of the present invention is to solve the above-mentioned conventional problems, and optimize the relationship among the Rz of the developing roll surface, the average interval Sm of the unevenness of the developing roll surface according to the JIS system, and the dynamic friction coefficient μ of the developing roll surface. Accordingly, it is an object of the present invention to provide a developing roll such as an electrophotographic printer and a developing device using the same, in which printing defects due to a negative afterimage and a positive afterimage hardly occur due to improvement in toner transportability and peelability. .

[0008]

According to the present invention, there is provided a semiconductive roll comprising a conductive shaft and an elastic semiconductive layer located outside the conductive shaft, wherein the semiconductive roll comprises: The relationship among the ten-point average roughness Rz of the surface of the roll, the average interval Sm of irregularities, and the dynamic friction coefficient μ is 0.1 ≦ (1 / Sm) × ((Sm
/ 2) ² + (Rz) ² ) ^1/2 × μ ≦ 1.0, where Sm = 10 to 200 × 10 ⁻⁶ m, Rz = 1 to 20
× 10 ⁻⁶ m, μ = 0.1 to 1.2.

A latent image carrier for carrying an electrostatic latent image; a charging roll for charging the latent image carrier; and a developing device for supplying toner to the electrostatic latent image carried on the latent image carrier. A developing device comprising a roll and a cleaning mechanism for removing unnecessary toner carried on the latent image carrier, wherein the developing roll comprises the semiconductive roll.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an elastic semiconductive roll according to the present invention will be described with reference to FIGS. FIG.
Shows an embodiment of a semiconductive roll according to the present invention,
(A) is a cross-sectional view showing a state in which an elastic semiconductive layer (solid) is provided outside the conductive shaft, (b) is a cross-sectional view of a roll shown in (a) in which a coating material layer is formed, (C)
FIG. 4 is a cross-sectional view of a structure in which an elastic semiconductive layer (sponge) and a coating material layer are provided outside a conductive shaft. FIG. 2 shows an embodiment of the developing device according to the present invention, and is a schematic view of a developing device provided with the semiconductive roll shown in FIG. 1 as a developing roll.

First, a semiconductive roll according to an embodiment of the present invention will be described with reference to FIG. The semiconductive roll 10 shown in FIGS. 1A and 1B includes an elastic semiconductive layer (solid) 12 outside a conductive shaft 11, and a coating material layer 13 formed outside the layer. . A semiconductive roll 20 shown in FIG. 1 (c) includes an elastic semiconductive layer (sponge) 22 instead of the elastic semiconductive layer (solid) 12 in FIGS. 1 (a) and 1 (b). It is. In addition, at least one elastic semiconductive layer may be used.

Next, the developing device according to the embodiment of the present invention shown in FIG. 2 will be described. The developing device 30 is an electrophotographic developing device using the semiconductive roll shown in FIG. 1 as a developing roll, and the toner 32 stirred by the stirrer 31 is transferred to the toner carrier layer by the toner transport roll 33. When the toner 32 charged between the toner transport roll and the developing roll adheres to the surface of the toner carrier layer and is transported to the position of the frictional charging blade 35, and the charge amount is further increased, At the same time, a thin layer of toner 32 is formed. The photoreceptor on the surface of the photoreceptor drum 36 is uniformly charged by a charging roll 37, and a light image of an original image is projected on the photoreceptor and converted into an electrostatic latent image having a surface potential changed in accordance with light and darkness of light. Then, the toner 32 corresponding to the charge of the electrostatic image adheres to the photosensitive member from the toner carrier layer of the developing roll 34 to form a toner image. A recording paper 38 is superimposed on the toner image, and an electric field is applied to the back of the recording paper 38 so that the toner 32 moves to the recording paper 38. Then, the toner image on the recording paper 38 is fused and fixed to the recording paper 38 by heating. The developing device 30 further includes a transfer roll 40,
A cleaning roll 41, an LED array 39, and the like are provided.

In the developing device 30, a toner carrier layer having a volume resistivity of 10 ¹ to 10 ⁹ Ω · cm is used. If the volume resistivity is out of the above range, problems such as generation of fog, reduction in transfer efficiency, inconsistency in print density, and dielectric breakdown of the organic photoreceptor are likely to occur.

Next, each member provided in the developing device 30 will be described. The conductive shaft body 11 is not particularly limited as a conductive material,
The so-called "core metal" made of iron, aluminum, SUS, or brass, or the one obtained by plating a thermoplastic resin or a thermosetting resin core, or a thermoplastic resin and / or a thermosetting resin As the conductivity-imparting agent, a core compounded with carbon black, metal powder, or the like is used.

The elastic semiconductive layer 12 of the developing roll 34
Include silicone rubber, ethylene-propylene-diene rubber, polyurethane, chloroprene rubber, natural rubber, butyl rubber, polyisoprene rubber, polybutadiene rubber,
Styrene-butadiene rubber, nitrile rubber, ethylene-
Propylene rubber, acrylic rubber, and mixtures thereof,
Filler such as fumed silica, precipitated silica, reinforcing carbon black, etc., and metal powder such as conductive carbon black, nickel, aluminum, copper, zinc oxide, tin oxide, etc. Metal oxide, core filler such as barium sulfate, titanium oxide or potassium titanate is blended with conductive fillers coated with tin oxide, and peroxides, hydrogen siloxane, isocyanate, etc. in the presence of platinum catalyst are added. What is kneaded together with a sulfuric acid is used.

When the kneaded product is formed, the conductive shaft 11 and the rubber or elastomer composition are integrated and separated using an extruder using a crosshead, and then a gear oven or IR. After primary vulcanization in a furnace, or after setting the conductive shaft in a mold,
A method of injecting the silicone rubber composition and performing primary vulcanization at room temperature or under heating, or a method of simultaneously heating and compression molding the conductive shaft 11 and the silicone rubber composition in a mold is used. Further, thereafter, the physical properties can be stabilized by performing secondary vulcanization for a certain period of time in a gear oven or the like.

If necessary, the molded product is subjected to a cylindrical grinding machine, a shot blaster, a sand blaster, a lapping machine,
A desired surface condition, preferably Rz is 3 to 1 by buffing or the like.
It can be processed to 5 × 10 ⁻⁶ m and Sm of 3 to 30 × 10 ⁻⁶ m. Further, in order to improve the durability of the surface-treated molded article, a coating material layer 13 in which a protective coating material is coated with a uniform thickness may be formed on the surface of the molded article.

The resin and / or elastomer used for the coating material layer 13 is not particularly limited, but those having an amino group and / or a hydroxyl group are preferred. Examples include alkyd resins, alkyd resin modifications such as phenol-modified or silicone-modified, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluororesins, phenolic resins, polyamide resins, urethane resins, and mixtures thereof. . In addition, a crosslinking agent such as an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, and a hydrogen siloxane compound is used for the crosslinking. Further, the coating material layer 13 may be formed by uniformly applying a coating material containing only these resins and elastomers. However, a conductive powder or an ion-conductive substance may be added to these resins or elastomers. It is even better if the coating material itself is semiconductive.

The conductive shaft 11 has one end grounded or a bias voltage applied thereto to charge the electrostatic latent image carrier, inject charge into the toner, adsorb the toner,
The electrostatic latent image can be developed, charged, and transferred by transferring the toner to the electrostatic latent image carrier, and is a support for the elastic semiconductive layer 12 formed on the outer periphery.

The elastic semiconductive layer 12 functions as an electrode in the developing step and an electrode for contact charging and charge injection to the toner.
A uniform developing electric field is formed between the photosensitive member and the photosensitive member. The coating material layer 13 formed on the elastic semiconductive layer 12 carries the toner 32 on the surface of the developing roll 34 and conveys it by the unevenness of the surface, van der Waals force, mirror image force, Coulomb force and the like. Is what you do.

Therefore, the R on the surface of the elastic semiconductive layer 12
The relationship among z, Sm, and μ is 0.1 ≦ (1 / Sm) × ((Sm
/ 2) ² + (Rz) ² ) ^1/2 × μ ≦ 1.0, where Sm = 10 to 200 × 10 ⁻⁶ m, Rz = 1 to 20
By setting to ^10-6 m and μ = 0.1 to 1.2, the afterimage can be controlled by controlling the toner transporting property and the releasability, and at the same time, the charge is charged by the functional group contained in the resin of the coat layer 13. Therefore, a high-quality printed image free from printing defects can be maintained for a long period of time.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a conductive shaft 11, a shaft having a diameter of 10 mm and a length of 250 mm, which is formed by electroless nickel plating on a SUM 22 represented by a metal material according to JIS, is used. 16
(Shin-Etsu Chemical Co., Ltd.) was applied and baked at 150 ° C. for 10 minutes in a gear oven.

As the conductive rubber composition, 100 parts by weight of KE-78VBS (trade name of Shin-Etsu Chemical Co., Ltd.) which is a raw rubber of methyl vinyl silicone, and KE-76VBS (trade name of Shin-Etsu Chemical Co., Ltd.) which is a raw rubber of dimethyl silicone are used. 10 parts by weight of Asahi Thermal Co., Ltd. (trade name of Asahi Carbon Co., Ltd.) and 10 parts by weight of Aerosil 200 (trade name of Nippon Aerosil Co., Ltd.) as a fumed silica filler Parts, 0.5 parts by weight of a platinum catalyst C-19A (trade name of Shin-Etsu Chemical Co., Ltd.)
2.4 parts by weight of hydrogen siloxane C-19B (trade name of Shin-Etsu Chemical Co., Ltd.) was added and kneaded with a pressure kneader to prepare a silicone rubber composition.

Next, the silicone rubber composition was integrated and extruded using a crosshead with an extruder, and then heated and vulcanized at 300 ° C. for 15 minutes in a gear oven, and then vulcanized to a diameter of 20 mm together with the shaft. It was formed by sulfur bonding. Thereafter, secondary vulcanization was performed in a gear oven at 200 ° C. for 4 hours, and polished with a cylindrical grinder to produce a roll having a diameter of 16 mm, a rubber portion length of 210 mm, and a hardness of 50, and was used as a sample of Example 1.

Next, Nipporan 3022, which is a urethane-based paint, is coated on the surface of the roll produced in the same manner as described above.
100 parts by weight of Nippon Polyurethane Co., Ltd. and 20 parts by weight of Techpolymer MB20X-5 (trade name of Sekisui Plastics Co., Ltd.), which is a crosslinked polymethyl methacrylate-based bead, as a surface roughness adjusting material. Add, 8 in pot mill
After stirring and dispersing for a time, Coronate-L, a polyisocyanate-based crosslinking agent (trade name of Nippon Polyurethane Co., Ltd.)
After adding 5 parts by weight and spray coating, 15
Roll prepared by heating and curing at 0 ° C. for 30 minutes in Example 2
Sample.

A roll was prepared in the same manner as in Example 2 except that the amount of the techpolymer MB20X-5, which was crosslinked polymethyl methacrylate beads, was 30 parts by weight and 40 parts by weight. And the samples of Examples 3 and 4.

(Comparative Example) As a comparative example, a roll prepared by the same method as that of the sample of the above-mentioned Example 1 and having only the surface roughness increased was prepared. Further, in Example 2, instead of adding the Techpolymer MB20 × -5, which is a crosslinked polymethyl methacrylate-based bead, a roll having 15 parts by weight of coronate-L, which is a polyisocyanate-based crosslinker, was used. A sample of Comparative Example 2 was manufactured.

Each of the rolls prepared above was mounted as a developing roll on an electrophotographic printer using a commercially available negatively charged toner, and a printing test was performed.

The method of measuring the measured items is shown below. (1) Surface roughness Both Rz and Sm were measured for roughness in the circumferential direction according to the method of JIS BO601 1994. (2) Dynamic friction coefficient As shown in FIG. 3, a friction tester (3K made by HEIDON)
-34B / HEIDON-14 (product name))
Using RICHO 6200 A4T mesh (width 50 mm) (product name) as PC paper, friction speed is 600 mm
/ Min, the vertical load was 100 g, and the tangential friction coefficient of the outer peripheral surface of the roll was measured. In the figure, 51 is a load cell,
52 is a slide table, 53 is a weight, 54 is a V block, 55 is a sample roller, and 56 is PPC paper. (3) Afterimage The roll sample of the example is built into an electrophotographic printer after the initial and endurance tests, and black solid, halftone dot, 5% duty, white background printing, etc. are repeated to print black with a width of 10 mm and a length of 34.9 mm. Using the Macbeth densitometer, the Macbeth densitometer is used to measure the Macbeth density in the black print area and the black print area between the black print area and the black print area of the test print pattern provided with a solid black print area behind the black print area. The image was measured, and the difference was defined as an afterimage. (4) Toner adhesion amount The developing roll of the above-described embodiment is incorporated in a commercially available printer,
The printer was turned off during printing at a duty of 5%, the toner layer of the untransferred portion on the photosensitive drum was peeled off with a cellophane tape, and the amount of toner adhering per unit area was measured using an electronic balance. (5) Roll resistance A rubber roll is placed on a gold-plated electrode 5 mm longer than the entire length of the rubber, a 500 g weight is applied to both ends of the roll, and a voltage of 100 V is applied to apply a voltage of 100 V to the resistance between the rubber roll shaft and the rubber surface. Was measured. (6) Print density The roll sample prepared in the above example was incorporated into an electrophotographic printer after the initial and endurance tests,
Halftone dots, 5% duty, white background printing, etc. were repeated, and the Macbeth density of the black solid printed portion was measured using a Macbeth densitometer. (7) Fog The roll sample prepared in the above example was incorporated into an electrophotographic printer after the initial and endurance tests, and
Halftone dots, 5% duty, white background printing, and the like were repeated, and the Macbeth density of a 5% duty white background was measured using a Macbeth densitometer. (8) Black solid unevenness The roll sample prepared in the above example was incorporated into an electrophotographic printer after the initial and endurance tests,
Halftone dots, 5% duty, white background printing, etc. were repeated, and the presence or absence of uneven printing density in the solid black portion was visually determined.

The pass / fail judgment for each measurement item will be described below. (1) Print density Both initial and post-durability densities less than 1.3 are rejected. (2) Fog Both the initial and post-durability concentrations exceeding 0.015 were rejected. (3) Afterimage For negative afterimages, the acceptable range is -0.05 to +0.01. For positive afterimages, -0.05 to +0.05.
Was regarded as the acceptable range. (4) Uneven black solids If the black solid density was uneven both in the initial stage and after the endurance, it was rejected. (5) Toner fixation The roll surface after the durability test was observed with a microscope.

Table 1 shows the results of Examples 1 to 4 and Comparative Examples 1 and 2 in which the measurement and the pass / fail judgment were carried out by the above-mentioned measuring methods.

[0032]

[Table 1]

In Embodiments 1 to 4, 60
As a result of confirming the printing characteristics after the printing of 00 sheets, as shown in Table 1, there was no afterimage at the initial stage and over time, and a high-quality printed image was obtained. At the same time, microscopic observation of the surface of the semiconductive roll was carried out, but no abnormality such as toner fixation and deterioration of the roll material was found.

The elastic semiconductive layer is shown in FIG.
Similarly, good printing characteristics were obtained with a sponge having an elastic semiconductive layer as shown in (c).

Further, the same tests as in the above example were conducted on Comparative Examples 1 and 2, and as shown in Table 1, the pass / fail judgment was failed.

[0036]

According to the present invention, the dynamic friction coefficient on the roll surface is controlled.
By setting several μ to 0.1 to 1.2, the print density and
It has good image characteristics such as blur and afterimage, and
A semiconductive roll free of adhesion is obtained. Furthermore, low
Surface average roughness Rz, average spacing Sm of irregularities and dynamic
The coefficient of friction μ is 0.1 ≦ (1 / Sm) × ((Sm / 2)
² + (Rz)² )^1/2 × μ ≦ 1.0, where Sm
= 10-200 × 10^{− 6}m, Rz = 1-20 × 10
^-6m, μ = 0.1 to 1.2,
A more preferable semiconductive roll is obtained. Also mentioned above
Using a semiconductive roll with excellent properties as a developing roll
Is provided.

[Brief description of the drawings]

1A and 1B show an embodiment of a semiconductive roll according to the present invention, in which FIG. 1A is a cross-sectional view showing a state in which an elastic semiconductive layer (solid) is provided outside a conductive shaft, and FIG. Sectional view of a roll having a coating material layer formed on the roll shown in FIG.
(C) is a cross-sectional view of one provided with an elastic semiconductive layer (sponge) and a coating material layer outside the conductive shaft.

FIG. 2 shows an embodiment of a developing device according to the present invention, and FIG.
1 is a schematic view of a developing device provided with a semiconductive roll shown in FIG. 1 as a developing roll.

FIG. 3 is a schematic diagram of a friction tester for explaining measurement of a tangential dynamic friction coefficient on a roll outer peripheral surface.

[Explanation of symbols]

 10, 20 semiconductive roll 11, 21 conductive shaft body 12 elastic semiconductive layer (solid) 13, 23 coating material layer 22 elastic semiconductive layer (sponge) 30 developing device 31 stirrer 32 toner 33 toner transporting roll 34 developing roll 35 frictional charging blade 36 photosensitive drum 37 charging roll 38 recording paper 39 LED array 40 transfer roll 41 cleaning roll 50 friction tester 51 load cell 52 slide 53 weight 54 V block 55 sample roller 56 PPC paper

Continued on the front page (72) Inventor Kazuya Nakada 300-5 Toyohara, Motohara, Kanagawa-cho, Kodama-gun, Saitama F-term in Shin-Etsu Polymer Co., Ltd. Kodama Plant 2H077 AD06 AD13 AD17 AE02 AE03 AE10 FA01 FA12 FA22 FA26 FA27 3J103 AA02 AA13 AA14 AA15 AA51 BA41 FA07 FA18 FA23 FA30 GA02 GA52 GA58 HA03 HA04 HA05 HA12 HA15 HA18 HA20 HA32 HA33 HA36 HA37 HA41 HA48 HA52 HA53 HA54

Claims (2)

[Claims] 1. A semiconductive roll provided with a conductive shaft and an elastic semiconductive layer located outside the conductive shaft, wherein a ten-point average roughness of the surface of the semiconductive roll is provided. Rz, the average interval Sm of the irregularities and the dynamic friction coefficient μ are 0.1 ≦
(1 / Sm) × ((Sm / 2) ² + (Rz) ² )
^1/2 × μ ≦ 1.0, where Sm = 10 to 200 × 1
0 ⁻⁶ m, Rz = 1 to 20 × 10 ⁻⁶ m, μ = 0.1 to
1.2, a semiconductive roll. 2. A latent image carrier for carrying an electrostatic latent image, a charging roll for charging the latent image carrier, and a developing device for supplying toner to the electrostatic latent image carried on the latent image carrier A developing device comprising a roll and a cleaning mechanism for removing unnecessary toner carried on the latent image carrier, wherein the developing roll is constituted by the semiconductive roll according to claim 1. Developing device.