JP3155093B2 - Developing roller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing roller of a developing device employing a one-component non-magnetic system.

[0002]

2. Description of the Related Art In a developing device employing a one-component non-magnetic system, a developing roller has a large effect on image quality. The reason for this is that in a one-component non-magnetic developing device, the developing roller plays a role of giving an appropriate amount of charge to the toner, which is a major factor in determining the image quality.
In this one-component non-magnetic developing device, the surface of the developing roller is repeatedly subjected to friction by a toner regulating blade and toner, and the outermost layer of the developing roller is required to have excellent wear resistance.

Heretofore, consideration has been given to selecting the most appropriate raw rubber, a conductivity-imparting agent, various fillers, and the like as the elastic material used for the developing roller, and keeping the compounding composition of the rubber material suitable. Was. However, in the case of printing using a conventional developing roller using such an elastic material, particularly in printing using an uncharged toner, the background fog becomes large and the print quality is deteriorated. Sometimes fluctuated due to environmental changes.

Further, a developing roller made of a material such as silicone rubber contains a low-boiling siloxane, and this substance may migrate onto the surface of the developing roller due to blooming, and this may cause the toner to adhere to the photosensitive member or the photosensitive member. This is one of the causes of inconvenience such as loss of function.
In the developing device having the silicone rubber developing roller, the developing roller is set in contact with the photoconductor, and the low-boiling siloxane easily adheres to the photoconductor,
In particular, when the photoconductor is not used for a long time, a considerable amount of low-boiling siloxane easily adheres to the photoconductor at the contact portion of the photoconductor with the developing roller. As a result, the portion of the photoreceptor loses its function and may not be able to form an electrostatic latent image. That is, white streaks sometimes appear horizontally on the paper at a pitch corresponding to the circumferential length of the photoconductor.

[0005]

Under the conditions required for a one-component non-magnetic developing roller, the surface of the developing roller is subject to repeated friction by a toner regulating plate or toner, and the outermost layer is abrasion resistant. It is required to have excellent properties. It is also necessary that the material used for the outermost layer of the developing roller does not contain an additive such as a plasticizer which easily causes blooming, and that the outermost layer of the developing roller does not cause blooming. Also, if the dielectric constant or electrical resistance of the developing roller material changes due to temperature and humidity changes, the effective developing bias changes and affects the developing characteristics.Therefore, the material of the outermost layer of the developing roller also needs environmental stability. is there.

Incidentally, a developing roller composed of a silicone rubber alone component in the material of the developing roller, a developing roller composed of silicone rubber coated with silicone resin, a developing roller composed of urethane rubber sole component, and a developing roller composed of urethane rubber coated with urethane resin have been studied. However, none of the above-mentioned conditions required for a one-component non-magnetic developing roller were satisfied.

That is, the silicone rubber has a problem that the plasticizer blooms on the outermost layer of the developing roller, a problem that it is inferior in wear resistance and has no durability, and a problem that background fog occurs. In addition, when urethane resin is used for a one-component non-magnetic developing roller, fine particles of toner adhere to a developed product, so-called background fogging occurs, and the roller is easily worn and has no durability. There is a problem that water is easily absorbed and there is no moisture resistance.

Further, when urethane rubber is used for a one-component non-magnetic phenomenon roller, it is satisfactory in abrasion resistance, but it has a problem of charging ability to toner and environmental resistance, especially moisture resistance. However, there is a problem in that the background fogging occurs.

The present invention solves the above-mentioned problems of the conventional developing roller, and provides a developing roller for a phenomenon device employing a one-component non-magnetic system, which is excellent in moisture resistance and abrasion resistance and causes blooming. It is an object of the present invention to provide a developing roller which does not cause background fogging.

[0010]

To this end, the developing roller of the present invention is applied to a developing device employing a one-component non-magnetic system. The outermost layer of the developing roller was composed of a butadiene-based polymer represented by the following general formula.

Embedded image n represents a repeating unit, and 1,000 ≦ number-average molecular weight ≦ 10,000.

[0011]

According to the present invention, as described above, the developing roller
It is applied to a developing device employing a one-component non-magnetic system.
The outermost layer of the developing roller was composed of a butadiene-based polymer represented by the following general formula.

Embedded image n represents a repeating unit, and 1,000 ≦ number-average molecular weight ≦ 10,000. In this case, when the degree of moisture resistance of the developing roller in which the outermost layer of the roller is coated with the butadiene-based polymer is measured, the water supply rate is 0.1% or less. Also, when the degree of wear of the developing roller is measured, it is found that the developing roller has excellent wear resistance. Then, when the degree of background fogging occurring in the developed product manufactured using the developing roller is measured, it is found that the background fogging is extremely small. Further, even when the developing roller was not used for a long time, blooming did not occur.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. In a developing roller for a developing device adopting a one-component non-magnetic system, the outermost layer is made of polyamide, so that it has excellent abrasion resistance, does not cause blooming, and has background fog. Can never be. Further, as the polyamide which is the material of the outermost layer of the developing roller, a copolymer composed of 6 nylon, 6,6 nylon, 6,10 nylon, or a polyamide composed of 6 nylon, 6,6 nylon, 6,10 nylon, 12 nylon Copolymers are used. Number average molecular weight of the polyamide,
5,000 to 50,000, preferably 10,
2,000 to 25,000. The reason is that if the number average molecular weight is too small, the stability over time (particularly, moisture resistance) of the film will be low, and if the number average molecular weight is too large, there will be a problem in solubility in a solvent. Therefore, by using the polyamide, solubility can be improved and coating can be facilitated. In order to achieve the object of the present invention, in a developing roller for a developing device employing a one-component non-magnetic system, an outermost layer is formed of a butadiene-based polymer represented by the following general formula.

Embedded image

The number average molecular weight of the butadiene polymer in the present invention is 1,000 ≦ number average molecular weight ≦ 10,000.
Is preferred. The reason is that the number average molecular weight <1,000
If it is 0, the water absorption exceeds 0.5% and there is a problem in water resistance (moisture resistance). If its number average molecular weight is more than 10,000, it becomes difficult to obtain a uniform film due to an increase in the viscosity of the coating solution.
This is because workability is also poor.

Further, the 1.4 type and 1..
The ratio with type 2 is 60% for type 1.4 which affects rubber elasticity.
In the following, the rubber elasticity is low, and the adhesion to the base rubber is deteriorated. in this case,
Since the outermost layer of the developing roller is composed of a special butadiene-based polymer specifically prepared in the present invention, it has excellent moisture resistance, and has excellent abrasion resistance, without blooming,
In addition, a developing roller having no background fog can be provided.

[0015]

Example 1 100 parts by weight of dimethylpolysiloxane raw rubber (manufactured by Toray Dow Corning Silicone Co., Ltd.) having both molecular chains terminated with dimethylvinylsiloxy groups and fumed silica (Toray Dow Corning Silicone Co., Ltd.) 20 parts by weight) were uniformly mixed to prepare a silicone rubber stock. Next, carbon black (manufactured by Denki Kagaku KK, surface area 70 m ² / g) was added to 100 parts of the silicone rubber stock.
Was added, and at the same time, 0.5 parts by weight of dibutyl-t-butyl peroxide (manufactured by Toray Dow Corning Silicone Co., Ltd.) was blended and uniformly kneaded. The kneaded material in the form of a plate is fitted into a mold with a metal shaft in between,
After press vulcanization at 170 ° C. and 200 kg / cm ² for 10 minutes, secondary vulcanization was performed at 200 ° C. for 6 hours to obtain a developing roller base material.

On the other hand, the following solutions were prepared as coating agents for coating the developing roller base material.
25 parts by weight of soluble nylon CM8000 (manufactured by Toray Industries, Inc.) was dissolved in 100 parts by weight of a mixed solvent of methanol / chloroform (methanol: chloroform = 90: 10 by weight). The solution viscosity was 370 centipoise at 20 ° C. Next, the developing roller base material was immersed in this solution, pulled up at a pulling rate of 20 mm / min, and dried. The thickness was 20-25 μm.

The developing roller prepared by the above method is
After running 30,000 sheets continuously in 4 sizes, the change in image quality and the state of wear were examined. As a comparative example, the same continuous operation was applied to a developing roller containing only silicone rubber without coating. FIG. 1 is a graph in which the degree of wear of the developing roller of the first embodiment is measured, in which the horizontal axis represents the number of printed sheets and the vertical axis represents the surface roughness. The comparative example uses a silicone rubber developing roller without a coating. According to FIG. 1, it can be seen that the developing roller of the first embodiment is much more excellent in abrasion resistance than the developing roller without the coating of the comparative example.

The developing roller of the first embodiment did not cause blooming even when it was not used for a long time. FIG. 2 is a graph in which the degree of background fogging which occurs in a developed product manufactured using the developing roller of Example 1 is measured. The horizontal axis indicates the number of printed sheets, and the vertical axis indicates the occurrence of background fogging. It is plotted by taking%. In the comparative example, a silicone rubber developing roller having no coating and a polyester urethane rubber developing roller having no coating were used. FIG. 2 shows that the development roller of the first embodiment has very little background fog.

The developing roller coated with the coating of Example 1 has good image density, background fog and resolution from the initial printing to the end of 15,000 sheets. There was no deterioration in image quality due to the wear as described above. The polyamide used in Example 1 was 6 nylon,
It is a copolymer of 6,6 nylon, 6,10 nylon, and 12 nylon. By using the copolymer, solubility was improved and coating was facilitated. In addition, copolymers of 6 nylon, 6,6 nylon, and 6,10 nylon exhibited similar good workability and abrasion resistance.

Example 2 A developing roller base material was manufactured by the same manufacturing method as in Example 1. On the other hand, the following solutions were prepared as coating agents for coating the developing roller base material. That is, hydroxyl-terminated polybutadiene (Idemitsu Petrochemical Co., Ltd.)
100 parts by weight of polybd R-15HT (trade name), 57 parts by weight of methylene diisocyanate (Millionate-MTL: trade name, NCO content 28%, manufactured by Nippon Polyurethane Industry Co., Ltd.), and dibutyltin dilaurate (Kyodo Chemical ( 0.05 parts by weight of toluene 400
It dissolved in parts by weight. The solution viscosity is 400 centipoise (2
0 ° C).

The developing roller base material is immersed in this solution,
The coating was carried out at a lifting speed of 20 mm / min. The film thickness was 20 μm. As a comparative example, a developing roller substrate coated with polyamide was prepared. Preparation of the coating solution was performed as follows. Soluble nylon CM8000 (manufactured by Toray Industries, Inc.) 2
5 parts by weight were dissolved in 100 parts by weight of a mixed solvent of methanol / chloroform (methanol: chloroform = 90: 10 weight ratio). The solution viscosity was 370 centipoise at 20 ° C. Next, the developing roller base material was immersed in this solution, pulled up at a pulling rate of 20 mm / min, and dried. The film thickness was 20 μm.

FIG. 3 is a graph showing the degree of moisture resistance of the developing roller of Example 2 in which a butadiene-based polymer was coated on the outermost layer of the roller. Is plotted.
The comparative example uses a polyester-based urethane rubber developing roller and a polyether-based urethane rubber developing roller. According to FIG. 3, the water absorption of the polyester-based urethane rubber developing roller and the polyether-based urethane rubber developing roller exceeds 0.5%, whereas the water absorption of the butadiene-based polymer is 0.1% or less. It can be seen that the developing roller of Example 2 is extremely excellent in moisture resistance.

FIG. 4 is a graph showing the degree of abrasion of the developing roller of Example 2 in which the outermost layer of the roller was coated with a butadiene-based polymer. The number of prints is plotted on the horizontal axis, and the surface roughness is plotted on the vertical axis. Is plotted.
The comparative example uses a silicone rubber developing roller without a coating. FIG. 4 shows that the developing roller using the butadiene-based polymer of Example 2 for the outermost layer of the roller has excellent abrasion resistance.

FIG. 5 is a graph showing the degree of background fogging occurring in a developed product manufactured using the developing roller of the second embodiment. The horizontal axis represents the number of printed sheets, and the vertical axis represents the background. This is plotted by taking the percentage of occurrence of fogging. In the comparative example, a silicone rubber developing roller having no coating and a polyester urethane rubber developing roller having no coating were used. FIG. 5 shows that the developing roller of the second embodiment has very little background fog.

The blooming of the developing roller of Example 2 did not occur even when the developing roller was not used for a long time.

[0027]

As described in detail above, according to the present invention, the developing roller is applied to a developing device employing a one-component non-magnetic system. The outermost layer of the developing roller was composed of a butadiene-based polymer represented by the following general formula.

Embedded image n represents a repeating unit, and 1,000 ≦ number-average molecular weight ≦ 10,000. In this case, the film has excellent moisture resistance and abrasion resistance, does not cause blooming even when the developing roller is not used for a long time, and has very little background fog.

[Brief description of the drawings]

FIG. 1 is a graph showing abrasion resistance tests of a developing roller in which the polyamide of Example 1 is coated on the outermost layer of the roller and an uncoated developing roller.

FIG. 2 is a graph showing the background fog of the developing roller having the outermost layer coated with the polyamide of Example 1 and the developing roller of the comparative example.

FIG. 3 is a graph showing a moisture absorption test of a developing roller having a butadiene-based polymer of Example 2 coated on the outermost layer of the roller and a developing roller of a comparative example.

FIG. 4 is a graph of a wear resistance test of a developing roller having a butadiene-based polymer of Example 2 coated on the outermost layer of the roller and a developing roller of a comparative example.

5 is a graph showing a background fogging test of a developing roller having a butadiene-based polymer of Example 2 coated on the outermost layer of the roller and a developing roller of a comparative example. FIG.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takao Mizutani 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Tohru Ishihara 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (56) References JP-A-60-45272 (JP, A) JP-A-56-89766 (JP, A) JP-A-56-110941 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 13/08-13/095 G03G 15/08-15/095 G03G 15/02 101 G03G 15/16 103 G03G 21/06 F16C 13/00

Claims (1)

(57) [Claims] 1. A developing roller for a developing device employing a one-component non-magnetic system, wherein an outermost layer of the developing roller is formed of a butadiene-based polymer represented by the following general formula. Embedded image n represents a repeating unit, and 1,000 ≦ number-average molecular weight ≦ 10,000.