JPH09269648A - Production of developing roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the frictional resistance with a member in contact with a roller surface, to maintain a stable amt. of a toner carried in the initial stage of printing, and to stably obtain a high quality image by treating the surface of a developing roller with a dispersion liquid containing dispersion of specified fine particles. SOLUTION: The surface of a developing roller 11 is treated with a dispersion liquid 4 in which fine particles 3 having <=30μm average particle size are dispersed, so that the fine particles 3 are uniformly distributed on the roller surface. Namely, the developing roller 11 produced by forming an elastic layer 2 around a shaft 1 is dipped in dispersion liquid prepared by dispersing fine particles 3 in a solvent 4. The roller is drawn up and dried to uniformly distribute the fine particles on the roller surface. The drying conditions are controlled according to the kind and density of the fine particles in the dispersion liquid, and 70 to 110 deg.C and 2 to 6 hours for drying is preferable to completely remove the solvent 4 and to fix only the fine particles 3 on the developing roller 11. Thus, the developing roller 11 with which a high quality image can be formed can be completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a developing roller in an electrophotographic device such as a copying machine or a printer, an electrostatic recording device or the like.

[0002]

2. Description of the Related Art In recent years, with the progress of electrophotographic technology, there has been an increasing demand for a conductive member used in each electrophotographic process, and in particular, a developing roller used in a developing device has been attracting attention. The characteristic required for such a developing roller is not only a predetermined electric resistance value, but also a characteristic suitable for various developing mechanisms needs to be added.

Conventionally, as a developing method in the case of using a non-magnetic one-component developer as a developer (hereinafter referred to as toner), toner is supplied to a photosensitive drum holding a latent image to form a latent image on the photosensitive drum. A developing method (pressure developing method) in which a toner is attached to visualize a latent image is known. According to this method, since a magnetic material is unnecessary, the device can be simplified and downsized, and It is easy to color toner.

In this pressure developing method, a developing roller carrying toner is brought into contact with an electrostatic holding member holding an electrostatic latent image, such as a photosensitive drum, and toner is attached to the latent image on the electrostatic holding member. Therefore, it is necessary to form the developing roller with an elastic body having conductivity.

That is, in this pressure developing method, for example, as shown in FIG.
As shown in FIG. 2, a toner applying roller 14 for supplying toner and a photosensitive drum 15 holding an electrostatic latent image.
While the developing roller 11 is in contact with the photosensitive drum 15, the developing roller 11, the photosensitive drum 15 and the toner applying roller 14 rotate in the directions of the arrows in the figure, so that the toner 16 is applied with toner. Roller 14
Supplied to the surface of the developing roller 11 by the toner 1
6 is formed into a uniform thin layer by the stratifying blade 17, and in this state, the developing roller 11 rotates while contacting the photosensitive drum 15, so that the toner 16 formed in the thin layer is transferred from the developing roller 11 to the photosensitive drum 15. Attached to the latent image,
The latent image is made visible. In the figure, reference numeral 18 denotes a transfer portion, which is adapted to transfer the toner image onto a recording medium such as paper, and 19 denotes a cleaning portion, which is cleaned by a cleaning blade 20 of the surface of the photosensitive drum 15 after transfer. The residual toner is removed.

In this case, the developing roller 11 must rotate while securely holding the state in which the developing roller 11 is in close contact with the photosensitive drum 15. For this reason, silicone rubber is attached to the outer circumference of the shaft made of a highly conductive material such as metal. Elastic rubber such as NBR and EPDM, elastomer material such as polyurethane, and
Each sponge body or the like has a structure in which a conductive agent is mixed to form an elastic layer having conductivity.

[0007]

However, the above-mentioned conventional developing roller has the following drawbacks. 1. Elastic rubber such as silicone rubber, NBR, EPDM,
Alternatively, when the elastic layer is formed of an elastomer material such as polyurethane, a layer pressure regulating blade in contact with the developing roller,
Alternatively, the frictional resistance with the photoconductor is large, and when incorporated in an electrophotographic apparatus, there is a shake in driving, and density waviness called jitter occurs. 2. At the initial stage when the developing roller is installed, the toner conveyance amount becomes large, and sometimes an image defect occurs.

The present invention has been made in view of the above circumstances, and reduces the frictional resistance with a member in contact with the surface of the developing roller, and further secures a stable toner conveyance amount in the initial stage of printing, thereby ensuring stable operation. An object of the present invention is to provide a method for manufacturing a developing roller that can obtain a high-quality image.

[Means for Solving the Problems]

The method of manufacturing a developing roller according to claim 1 of the present invention is the method of manufacturing a developing roller in which an elastic layer is formed on the outer periphery of a good conductive shaft, wherein the surface of the developing roller has an average particle diameter of 30 μm or less. It is characterized in that it is treated with a dispersion liquid in which fine powder is dispersed.

The method of manufacturing a developing roller according to a second aspect of the present invention is characterized in that a resin layer is formed on the surface of the elastic layer and then treated with the dispersion liquid.

The developing roller manufacturing method according to a third aspect of the present invention is characterized in that the fine powder is a charge control agent.

BEST MODE FOR CARRYING OUT THE INVENTION

That is, the inventors of the present invention have made extensive studies on the surface condition of the developing roller, and as a result, the surface of the developing roller is treated with a dispersion liquid in which fine particles having an average particle diameter of 30 μm or less are dispersed to obtain a fine powder. The body can be evenly arranged on the surface of the developing roller, the frictional resistance with the member in contact with the surface of the developing roller can be reduced, and a stable toner conveyance amount can be secured in the initial stage of printing, so that a stable toner amount can be obtained. The present inventors have completed the present invention by finding that a high quality image can be obtained.

Further, by forming at least one resin layer on the surface of the elastic layer of the developing roller and then treating the surface with the dispersion before the resin is completely cured,
Since the resin and the fine powder can be physically fixed, a high quality image can be maintained for a long period of time.

By using the fine powder as the charge control agent, the charge amount of the toner can be controlled relatively arbitrarily depending on the charge polarity of the charge control agent used.

A method of manufacturing the developing roller 11 of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of surface treatment of the developing roller 11 of the present invention. Here, the developing roller having the elastic layer 2 formed on the outer periphery of the shaft 1 in advance by a known molding method is immersed in a dispersion liquid in which the fine powder 3 is dispersed in the solvent 4, and then the developing roller is pulled up and dried. The fine powder 3 is uniformly arranged on the surface of the developing roller. Further, as other processing methods, known coating film forming methods such as a spray coating method and a blade coater method can also be adopted. The drying condition after immersion varies depending on the type and concentration of the fine powder 3 in the dispersion liquid, but is preferably 70 to 110 ° C. for 2 to 6 hours. By satisfying this condition, the solvent 4 can be completely removed. Only the fine powder 3 can be removed and adhered to the developing roller, and the developing roller 11 can obtain a high quality image. Further, as will be described later, in the case where the resin layer is formed on the surface of the elastic layer 2 and then the surface treatment is performed with the above-mentioned dispersion liquid, it may be before or after the resin layer is completely cured. From the viewpoint of forming a high-quality image for a long period of time, it is preferable that the resin is not cured, and the resin causes swelling or the like due to the dispersion liquid, and after the fine powder 3 adheres to the resin, heating and curing causes the resin and The powder 3 can be physically fixed.

In the developing roller of the present invention, as shown in FIG. 1, an elastic layer 2 having conductivity is formed on the outer circumference of a shaft 1 of good conductivity. Here, as the shaft 1, any one can be used as long as it has good conductivity, but normally, a cored bar made of a solid metal body or a metal cylinder hollowed out inside A metal shaft such as a body is used.

For the elastic layer 2, an elastomer such as conductive rubber or polyurethane or a foam material can be used as a base material.

First, the case where the elastic layer 2 is a conductive rubber will be described. In this case, as the rubber material forming the non-foamed conductive rubber, nitrile butadiene rubber, natural rubber, butyl rubber, nitrile rubber, isoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene- Ordinary rubber such as propylene-diene terpolymer rubber (EPDM), chloroprene rubber, acrylic rubber, polynorbornene rubber or styrene-butadiene-styrene (SB
S), styrene-butadiene-styrene hydrogenated product (SEB
It is possible to use thermoplastic rubbers such as S) and mixtures thereof.

As the foamed conductive rubber, ethylene-propylene-diene terpolymer rubber (EPDM),
Chloroprene rubber, a mixture of chlorosulphonated polyethylene with a conductive agent , a foam of epichlorohydrin and ethylene oxide copolymer rubber, or a foam of a mixture of epichlorohydrin and ethylene oxide with a conductive agent can be preferably used. .

As the conductive agent to be blended with these rubber compositions, powdery examples will be given. Conductive carbon such as Ketjenblack EC and acetylene black, and SA.
F, ISAF, HAF, FEF, GPF, SRF, F
Carbon for rubber such as T and MT, carbon for color (ink) that has been subjected to oxidation treatment, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, Examples thereof include metals such as germanium and metal oxides, and conductive polymers such as polyaniline, polypyrrole, and polyacetylene. The compounding amount thereof may be 3 to 100 parts by weight, particularly 5 to 50 parts by weight, based on 100 parts by weight of all rubber components, whereby the volume resistivity of the elastic layer 2 is 10 ² to 10 parts by weight.
It can be adjusted to ¹⁰ Ω · cm.

Next, the case where the elastic layer 2 is polyurethane will be described. In this case, the polyurethane foam or elastomer may be any one produced by various methods, for example, a method of blending carbon black into a polyurethane prepolymer and subjecting the prepolymer to a crosslinking reaction, and blending a conductive material with a polyol. The polyol can be obtained by a method such as a method of reacting this polyol with polyisocyanate by a one-shot method.

The urethane used as the base material when the elastic layer 2 is polyurethane is a polyhydroxyl compound, a polyol used in the production of general flexible polyurethane foams and urethane elastomers, for example, having a polyhydroxyl group at the end. Examples include polyether polyols, polyester polyols, and polyether polyols that are copolymers of both, so-called polyolefins such as polybutadiene polyols and polyisoprene polyols, so-called obtained by polymerizing ethylenically unsaturated monomers in polyols. Common polyols such as polymer polyols can be used. Also,
As the polyisocyanate compound, similarly, polyisocyanates used for producing general flexible polyurethane foams and urethane elastomers, that is, tolylene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI, Aliphatic polyisocyanate having 2 to 18 carbon atoms, 4 to carbon atoms
No. 15 alicyclic polyisocyanates and mixtures and modified products of these polyisocyanates, for example, prepolymers obtained by partially reacting with polyols and the like are used.

As the conductive agent to be blended with these polyurethanes, the same conductive agent as in the case of the above rubber composition and an ionic conductive agent made of an inorganic ionic substance such as lithium perchlorate or an organic ionic substance such as a quaternary ammonium salt are used. Agents, cationic surfactants, anionic surfactants, zwitterionic surfactants such as various betaines, and nonionic antistatic agents such as hydrophilic polyethers and polyesters may be used in combination. In the case of urethane, it is also preferable that the polyol component is prepolymerized with isocyanate.
The blending amount is 0.5 to 100 parts by weight of urethane.
It can be 50 parts by weight, particularly 1 to 30 parts by weight, whereby the volume resistivity of the elastic layer 2 is 10 ² to 10 ¹⁰ Ω.
cm. Other conductive agents include tetracyanoethylene, tetracyanoquinodimethane,
Benzoquinone, chloranil, anthraquinone, anthracene, dichlorodicyanobenzoquinone, ferrocene,
An electron accepting substance capable of forming a charge transfer complex such as phthalocyanine can be blended, and the blending amount in that case is 0.001 to 20 parts by weight, particularly 0.01 to 1 part by weight, relative to 100 parts by weight of urethane. Can be

The hardness of the elastic layer 2 is not particularly limited,
According to JIS-A scale, it is preferably 60 ° or less, particularly 10 to 55 °. In this case, if the hardness exceeds 60 °, the contact area with the photosensitive drum and the like may be small, and good development may not be performed. On the contrary, if the hardness is too low, the compression set becomes large, and the development may be difficult for some reason. When the roller is deformed or eccentric, uneven density of the image occurs. Therefore, even when the hardness of the elastic layer 2 is low, it is preferable that the compression set be as small as possible, specifically, 20% or less.

As the dispersion liquid for treating the surface of the developing roller, a fine powder 3 to be adsorbed and held is dispersed in water or a solvent 4 such as alcohols, ketones or aromatics. A dispersion liquid in which the concentration of the fine powder is adjusted to 1 to 50% by weight is preferable, and this concentration is 1% by weight.
If it is less than 50% by weight, the treatment effect does not appear, and if it exceeds 50% by weight, the viscosity of the dispersion liquid increases or the fine powder 3 precipitates, which makes it difficult to perform uniform treatment, which is not preferable.

Here, the fine powder 3 is not particularly limited, and the average particle diameter is 30 μm or less, more preferably 3 to 30 μm.
As long as it is a toner, a charge control agent, an inorganic oxide, carbon black, silica, a silicone resin, a fluorine resin, a polyamide resin and the like can be mentioned. In particular, when a toner is used for the fine powder 3, even if the fine powder 3 adsorbed and held is mixed in the toner box, no problem occurs, and good developing characteristics can be obtained even in long-term operation. It is preferably used. When an inorganic oxide is used as the charge control agent in the fine powder 3, the toner charge amount can be controlled relatively arbitrarily depending on the charge polarity of the charge control agent used. When silica, silicone resin or fluorine resin is used for the fine powder, the tackiness of the surface can be improved.

When the average particle size is 30 μm or more,
The uneven gap due to the particles adsorbed and held on the surface becomes large, and the toner charge amount becomes uneven, so that an image defect occurs in a normal electrophotographic process.

As described above, when the fine powder 3 is adsorbed and held on the surface, the friction coefficient on the surface of the developing roller is reduced, and when the fine powder 3 is incorporated in an electrophotographic apparatus, smooth driving becomes possible and jitter or the like occurs. A high quality image can be obtained, and the toner transfer amount is large because the frictional electrification amount between the roller and toner is large in the initial stage, but using this method, stable toner is obtained even in the initial stage. The transport amount can be obtained.

Here, the reason why the toner carrying amount becomes stable is that holding the fine powder 3 makes the surface state smooth and the physical initial toner carrying amount decreases. Further, when toner is used as the fine powder, the toner is triboelectrically charged through the attracted / held toner, so that the toner charge amount is reduced. It is considered that this reduces the toner transport amount in the initial stage.

If the toner conveyance amount is too large, that is, the toner layer on the roller becomes thick, the following problems will occur.

When the toner layer becomes thicker, the toner particles themselves are charged, so that the charge of the entire toner layer becomes large, so that a high surface potential is developed in the toner surface layer close to the photoreceptor. It will be. That is, in the developing process, when a predetermined developing bias is applied to the developing roller to cause the toner to fly to the photoconductor,
The surface layer has a high potential equal to or higher than the developing bias because the electric charge of the entire toner layer is excessive, and in some cases, for example, in the reversal developing process, the developing roller surface potential is exposed to light. The image does not fall between the dark decay potential on the body and the charging potential, and the potential becomes higher than the charging potential of the photoconductor, so that the toner flies to the white printed portion, so-called image fogging occurs.

The developing roller of the present invention can be incorporated in an ordinary developing device using a magnetic or non-magnetic one-component developer. Specifically, as shown in FIG. 2, it is for toner application for supplying toner. Between the roller 14 and the photosensitive drum 15 holding the electrostatic latent image, the developing roller 11 of the present invention is not in contact with or in contact with the photosensitive drum 15, and is in contact with or slightly apart from the toner applying roller 14. Is arranged,
By rotating the developing roller 11, the photosensitive drum 15, and the toner applying roller 14 in the directions of the arrows in the drawing, the toner 16 is supplied to the surface of the developing roller 11 by the toner applying roller 14, and this toner is used as a layering blade. The toner is formed into a uniform thin layer by 17, and in this state, the developing roller 11 rotates in contact with the photosensitive drum 15, so that the toner formed in the thin layer adheres from the developing roller 11 to the latent image on the photosensitive drum 15. The latent image is visualized. Note that the details of FIG. 2 have been described in the related art, and thus description thereof will be omitted.

[0033]

EXAMPLES The present invention will now be described specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. [Example 1] 100 parts of polyether polyol (OH number 33) (Exenol (registered trademark) 828 manufactured by Asahi Glass Co., Ltd.) having a molecular weight of 5000 by adding propylene oxide and ethylene oxide to glycerin MDI NCO% = 23% (Sumijour (registered trademark) PF manufactured by Sumitomo Bayer Urethane Co., Ltd.) 25.0 parts-1, 4-butanediol 2.5 parts-dibutyltin dilaurate 0.01 part-4th grade 0.25 parts of ammonium salt (KS-555 manufactured by Kao Corporation)

These were stirred, then poured into a mold heated to 110 ° C., and cured for 2 hours to form an elastic layer 2 on the outer circumference of a metal shaft to obtain a developing roller 11. The surface of the obtained developing roller was polished to a predetermined surface condition. The roller manufactured in this way is charged with a negative charge control agent 5 g.
(Average particle size 7 μm, Copy Charge NEG manufactured by Hoechst
VP2036) was immersed in a dispersion liquid in which 100 g of methanol (solvent) was dispersed for 1 minute to adsorb and hold the fine powder 3 on the surface of the roller.

Example 2 Melamine resin (Super Beckamine, manufactured by Dainippon Ink and Chemicals, Inc.) as the main material of the resin layer
And alkyd resin (Beckosol, manufactured by Dainippon Ink and Chemicals, Inc.) were mixed at 5: 5 to prepare a MEK: toluene: methanol = 7: 2: 1 solvent so that the resin concentration was 20%. Then, it was heated to 50 ° C. with stirring to dissolve it. In this dispersion, as a carbon, Printex 3
5 (manufactured by Degussa) was mixed in a resin concentration of 20 phr and dispersed for 1 hour with a sand grinder to obtain a coating material. Next, the developing roller obtained in Example 1 was dipped in this paint to form a resin layer on the surface thereof.

Finally, the prepared roller is made of titanium oxide 7 g.
(Average particle diameter 5 μm, trade name “FT500W” (manufactured by Ishihara Sangyo Co., Ltd.) inorganic oxide) was immersed in a dispersion liquid in which 100 g of methyl ethyl ketone (solvent) was dipped for 2 minutes, and fine powder 3 was formed on the surface of the developing roller. Was adsorbed and retained.

Comparative Example 1 The developing roller obtained with the composition of Example 1 was used as it was without holding the fine particles 3.

The following image characteristic test and roller characteristic test were conducted on the developing rollers obtained in Examples 1 and 2 and Comparative Example 1 above. The results are shown in Table 1.

(1) Image Fogging Each roller is attached as a developing roller to the developing unit shown in FIG. 2, and non-magnetic one-component toner having an average particle diameter of 7 μm is used, and the roller is rotated at a peripheral speed of 60 mm / sec. The initial image quality (especially the image fog)
Was evaluated. (2) Roller surface potential Each roller was mounted as a developing roller in the developing unit portion shown in FIG. 2 and rotated at a peripheral speed of 50 mm / sec to form a uniform thin toner layer on the surface of the developing roller. An external power source applied -500 V to this roller shaft, and the roller surface potential at that time was measured. (3) Toner transport amount As in (2), a uniform thin toner layer is formed on the roller,
This thin toner layer was wiped off with a non-woven fabric of known weight, and the weight was measured. (4) Toner charge amount The toner carried on the surface of the developing roller was measured using a Faraday gauge. (5) Friction coefficient HEIDON-14 manufactured by HEIDON was used to measure the coefficient of dynamic friction when friction was made perpendicular to the longitudinal direction of the roller, and the value for the roller of Comparative Example 1 was set to 1, and the ratio is shown in Table 1.

[0040]

[Table 1]

[0041]

[0042]

As described above, according to the present invention, by adsorbing and holding the fine powder on the surface of the developing roller,
It is possible to provide a method for manufacturing a developing roller that can stably obtain a high-quality image by reducing the frictional resistance with a member in contact with the roller and by ensuring a stable toner conveyance amount in the initial stage of printing. Become.

[Brief description of drawings]

FIG. 1 is an example of a surface treatment of a developing roller of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of a developing device.

[Explanation of symbols]

 Reference Signs List 1 shaft 2 elastic layer 3 fine powder 4 solvent 11 developing roller 14 toner applying roller 15 photosensitive drum (latent image holding member) 16 toner (non-magnetic one-component developer) 17 blade 18 transfer section 19 cleaning section 20 cleaning blade

Claims (3)

[Claims] 1. A method of manufacturing a developing roller having an elastic layer formed on the outer periphery of a good conductive shaft, wherein the surface of the developing roller is treated with a dispersion liquid in which fine powder having an average particle diameter of 30 μm or less is dispersed. A method of manufacturing a developing roller, comprising: 2. The method of manufacturing a developing roller according to claim 1, wherein a resin layer is formed on the surface of the elastic layer and then treated with the dispersion liquid. 3. The method of manufacturing a developing roller according to claim 1, wherein the fine powder is a charge control agent.