JP2018017960A - Developer carrier, processing cartridge, and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably suppress a fog amount with time in a low-humidity environment and in a high-humidity environment as well while maintaining an excellent development property, and attain an excellent image.SOLUTION: The developer carrier includes a base material, an elastic layer 14b1, and a surface layer 14b2 in that order. The surface layer is an aluminum oxide film containing a chemical bond (i) expressed by a specific expression (1) and at least one chemical bond (ii) selected from the group of a chemical bond expressed by a specific expression (2-1) and a chemical bond expressed by a specific expression (3-1).SELECTED DRAWING: Figure 4

Description

  The present invention relates to a developer carrier, a process cartridge, and an electrophotographic apparatus.

In an electrophotographic apparatus such as a laser printer using an electrophotographic process, a contact developing system using a developing roller having an elastic layer has been proposed as a conventional developing system using a single component toner.
FIG. 2 is a schematic diagram showing a configuration of an electrophotographic apparatus that employs a contact developing system using a developing roller (developer carrying member) having an elastic layer. The developing roller 14 carries a non-magnetic developer, and development is performed by bringing the developing roller 14 into contact with the surface of the photoreceptor 1 which is an electrophotographic photoreceptor. The developer is supplied to the developing roller 14 by a supply roller 15 that is in contact with the developing roller 14. The supply roller 15 carries the developer from the inside of the developing container 13, adheres to the developing roller 14, and also has a function of temporarily removing the developer remaining on the developing roller 14. Charge regulation by developer layer regulation and frictional charging of the developer adhered on the developing roller 14 is performed by bringing the toner regulating member 16 into contact with the developing roller 14. As the toner regulating member 16, it has been proposed to use a blade-shaped member that cantilever-supports a thin metal plate and abuts the abdominal surface of the opposed portion against the developing roller 14. The developer coated on the developing roller 14 by the toner regulating member 16 develops the electrostatic latent image formed on the photoreceptor 1 by the bias potential applied on the developing roller 14 (Patent Document 1). .

JP 62-118372 A

  It is known that the charge imparting property of the toner is lowered in a high humidity environment. In particular, in the one-component contact development method in which charging is applied to the toner by frictional charging with the toner regulating member, the toner has very few opportunities to obtain electric charge, and thus the effect of lowering the charging property of the toner is large. As a result, a problem due to a decrease in charge imparting property to the toner, for example, an increase in the fog amount occurs. The fog is an image defect in which toner is slightly developed in a white portion (non-printing portion) that is not originally printed and appears like a background stain, and is a problem caused by a decrease in charge imparting property to the toner.

In a region where the photosensitive member and the developing roller are in contact with each other via the toner, a voltage that applies a force from the photosensitive member to the developing roller is applied to the charged toner in the non-printing portion. According to Patent Document 1, in the voltage application region where the photosensitive member and the developing roller are in contact, the voltage applied as described above causes the toner charge to escape toward the developing roller, and the fog amount due to the toner charge attenuation is reduced. It is considered to increase. As a suppression method, it has been proposed to increase the volume resistance of the developing roller. However, when the volume resistance is simply increased, developability such as density reduction is caused.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a developer carrying body that stably suppresses fogging while maintaining developability, and the developer carrying body. A process cartridge and an electrophotographic apparatus.

According to the present invention,
A developer carrier having a base, an elastic layer and a surface layer in this order,
The surface layer is
(I) a chemical bond represented by the following formula (1);
(Ii) An aluminum oxide film having a chemical bond represented by the following formula (2-1) and at least one chemical bond selected from the group consisting of a chemical bond represented by the following formula (3-1) A developer carrier is provided.

(In Formula (2-1), Formula (2-2) is a bidentate ligand, and X ¹ represents a carbon atom that forms a cyclic structure together with oxygen atoms in Al ³⁺ and the bidentate ligand. The number of carbon atoms is 2 to 5, and at least one of the carbon atoms has an alkyl group having 1 to 18 carbon atoms as a substituent.

(In Formula (3-1), Formula (3-2) is a bidentate ligand, and X ² represents a carbon atom that forms a cyclic structure with Al ³⁺ and an oxygen atom in the bidentate ligand. The number of carbon atoms is 2 to 5, and at least one of the carbon atoms has an alkyl group having 1 to 18 carbon atoms as a substituent.

According to the present invention, the developing means having the developer carrying member and at least one means selected from the group consisting of an electrophotographic photosensitive member, a charging means, and a transferring means are integrally supported, and electrophotographic A process cartridge that is detachable from the apparatus main body is provided.
Further, according to the present invention, there is provided an electrophotographic apparatus having a developing means having the developer carrying member, an electrophotographic photosensitive member, a charging means, an exposing means, and a transferring means.

  According to the present invention, it is possible to provide a developer bearing member and an electrophotographic apparatus that stably suppress fogging over time while maintaining developability.

1 is a schematic view of an electrophotographic apparatus according to the present invention. 2 is a schematic view of a process cartridge according to Embodiment 1. FIG. 6 is a schematic diagram of a process cartridge according to Embodiment 2. FIG. It is the schematic of the developing roller which concerns on this invention. It is the schematic explaining the volume average resistance measurement of a roller. FIG. 6 is a schematic diagram illustrating a change in toner charge before and after passing through a developing nip portion.

  FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to the present invention. The electrophotographic apparatus shown in FIG. 1 is a full-color laser printer that uses an electrophotographic process. The overall schematic configuration of the electrophotographic apparatus according to the embodiment of the present invention will be described below. However, the dimensions, materials, shapes, and relative arrangements of the components described in the embodiments described below are intended to limit the scope of the present invention only to those unless otherwise specified. It is not a thing.

<< Embodiment 1 >>
An electrophotographic apparatus applied to Embodiment 1 to which the present invention is applied is shown in FIGS.
FIG. 2 is a schematic configuration diagram of the process cartridge according to the first embodiment of the present invention. A photoreceptor 1 (electrophotographic photoreceptor) which is an image carrier carries an electrostatic latent image. A developing roller 14 that is a developer carrying member is disposed in contact with the photosensitive member 1. The developing device 4 serving as a developing unit includes a developing roller 14, and supports the developer on the developing roller 14, and develops the electrostatic latent image on the photoreceptor 1 with the developer. More details are as follows.

In this electrophotographic apparatus, the photosensitive member 1 is rotated in the direction of an arrow (counterclockwise direction) and is charged to a uniform potential Vd by a charging roller 2 as a charging unit.
Next, exposure is performed with laser light from a laser optical device 3 serving as exposure means, and an electrostatic latent image is formed on the surface of the photoreceptor 1. The electrostatic latent image is developed by the developing device 4 and visualized as a toner image.

The visualized toner image on the photoreceptor 1 is transferred to the intermediate transfer member 6 by the primary transfer device 5 (transfer means), and then transferred to the paper 8 as a recording medium by the secondary transfer device 7.
Untransferred toner remaining on the photoreceptor 1 without being transferred is scraped off by a cleaning blade 9 which is a cleaning device. The cleaned photoreceptor 1 repeats the above-described operation to form an image.
On the other hand, the toner image transferred to the paper 8 is fixed on the paper 8 by the fixing device 10. Thereafter, the paper 8 is discharged out of the machine.

As shown in FIG. 2, the photosensitive member 1, the charging roller 2, the developing device 4, and the cleaning blade 9 are integrally configured as a cartridge 11 that can be attached to and detached from the main body of the electrophotographic apparatus. .
As shown in FIG. 1, four mounting portions for the cartridge 11 are prepared in the main body. A cartridge 11 filled with toners of yellow, magenta, cyan, and black is mounted from the upstream side in the moving direction of the intermediate transfer body 6, and the four color toners are sequentially transferred to the intermediate transfer body 6 to perform color transfer. An image can be formed.

The photoreceptor 1 is formed by laminating an organic photoreceptor on which a positive charge injection preventing layer, a charge generation layer, and a charge transport layer are laminated in this order on an aluminum cylinder as a substrate. Further, polyarylate resin was used as the charge transport layer of the photoreceptor 1, and the thickness of the charge transport layer was adjusted to 23 μm.
The charge transport layer is formed by dissolving a charge transport material together with a binder in a solvent. Examples of organic charge transport materials include acrylic resins, styrene resins, polyester resins, polycarbonate resins, polyarylate resins, polysulfone resins, polyphenylene oxide resins, epoxy resins, polyurethane resins, alkyd resins, and unsaturated resins. It is done. These charge transport materials can be used alone or in combination of two or more.

The charging roller 2 is provided with a semiconductive rubber layer on a metal core which is a conductive support, and this charging roller is about 10 ⁵ Ω when a voltage of 200 V is applied to the conductive drum. The electrical resistance is shown.
The developing device 4 includes a toner 12 that is a developer, a developing container 13 that is a developer container, a developing roller 14 that is a developer carrier, a supply roller 15 that supplies the toner 12 to the developing roller 14, and a restriction. A blade 16. The regulating blade 16 is a developer regulating member that regulates the toner on the developing roller 14.
The developing roller 14 as a developer carrying member has a base, an elastic layer, and a surface layer in this order. Details regarding the developing roller 14 will be described later.

The supply roller 15 rotates in contact with the developing roller 14, and one end of the regulating blade 16 is in contact with the developing roller 14.
The supply roller 15 is provided with a foamed urethane layer 15b around a cored bar electrode 15a having an outer diameter of φ5.5 (mm) which is a conductive support. The outer diameter of the entire supply roller 15 including the urethane foam layer 15b is φ13 (mm). The intrusion amount of the supply roller 15 and the developing roller 14 is 1.2 mm.

  The supply roller 15 rotates in a direction in which the speeds of the supply roller 15 and the developing roller 14 are opposite to each other. The powder pressure of the toner 12 existing around this acts on the urethane foam layer 15b, and the supply roller 15 rotates, whereby the toner 12 is taken into the urethane foam layer. The supply roller 15 including the toner 12 supplies the toner 12 to the developing roller 14 at a contact portion with the developing roller 14, and further rubs the toner 12 to give a preliminary triboelectric charge to the toner 12. On the other hand, the supply roller 15 that supplies toner to the developing roller 14 also has a role of peeling off toner remaining on the developing roller 14 without being developed in the developing unit.

  The toner 12 supplied from the supply roller 15 to the developing roller 14 reaches the regulating blade 16 and is adjusted to a desired charge amount and toner layer thickness. The regulating blade 16 is a SUS blade having a thickness of 80 μm, and is disposed in the direction against the rotation of the developing roller 14. The regulating blade 16 regulates the toner 12 on the developing roller 14 to obtain a uniform toner layer thickness and obtain a desired charge amount by frictional charging by rubbing. Further, a voltage having a potential difference of −200 V with respect to the developing roller 14 was applied to the regulating blade 16. This potential difference is for stabilizing the toner coat layer.

The toner layer formed on the developing roller 14 by the regulating blade 16 is transported to the developing unit in contact with the photoreceptor 1 and reverse development is performed in the developing unit.
At the contact position, the amount of penetration of the developing roller 14 into the photoreceptor 1 is set to 40 μm by a roller (not shown) at the end of the developing roller 14. When the surface of the developing roller 14 is deformed by being pressed against the photoreceptor 1, a developing nip portion is formed, and development can be performed in a stable contact state. The developing roller 14 rotates in the same direction with a peripheral speed ratio of 117% with respect to the photosensitive member 1 at the developing nip portion with the photosensitive member 1. The reason for providing such a peripheral speed difference has a role of stabilizing the amount of toner to be developed. The development nip portion means a contact portion between the developing roller 14 and the photoreceptor 1.

Next, specific voltages in the present embodiment will be described. By applying −1050 V to the charging roller, the surface of the photoreceptor 1 is uniformly charged to −500 V, thereby forming a dark potential (Vd). The printing unit is −100 V by a laser as an exposure unit. It was adjusted to (bright potential · Vl). At this time, by applying a voltage (Vdc) of −300 V to the developing roller 14, the negative polarity toner is transferred to a bright potential to perform reversal development.
Also, | Vd−Vdc | was called Vback, and Vback was set to 200V.

Toner 12 (one-component non-magnetic toner) as a developer was adjusted to include a binder resin and a charge control agent, and was prepared to have a negative polarity by adding a fluidizing agent or the like as an external additive. . The toner 12 was prepared by a polymerization method, and the volume average particle diameter was adjusted to about 5 μm.
Furthermore, the amount of toner filled in the developing device was set to an amount that can print 5000 sheets of an image with a 5% image ratio. A specific example of a horizontal line with an image ratio of 5% means an image in which 19 dot line non-printing is repeated after printing 1 dot line.

  In the image forming process, the photosensitive member 1 is rotationally driven in the direction of arrow r in the figure by the electrophotographic apparatus at a speed of 120 mm / second. In addition, the electrophotographic apparatus has a low speed mode with a process speed of 60 mm / second in order to secure a heat quantity for fixing when a thick recording paper (thick paper) is passed. In this embodiment, the operation is performed only in two types of process modes. However, a plurality of process modes may be provided depending on the recording paper, and control corresponding to each process mode can be executed. May be.

<< Embodiment 2 >>
FIG. 3 is a schematic configuration diagram of a process cartridge according to the second embodiment of the present invention. The image recording apparatus of the present embodiment is a laser printer using a transfer type electrophotographic process and a toner recycling process (cleanerless system). The same points as those of the image recording apparatus of the first embodiment, such as the photoreceptor 1 as an image carrier, the developing roller 14 as a developer carrier, and the developing device 4 as a developing unit, will not be described again. Describe the differences. A characteristic point in this embodiment is that the drum cleaner 9 is discarded and the transfer residual toner is recycled. The transfer residual toner is circulated so as not to adversely affect other processes such as charging, and the toner is collected in the developing device. Specifically, the following configuration is changed with respect to the first embodiment.

  For charging, the same charging roller 2 as that of the first embodiment is used. In this embodiment, the charging roller 2 includes a charging roller contact member 17 for the purpose of suppressing toner contamination of the charging roller. Even when the charging roller 2 is contaminated with toner of the opposite polarity (positive polarity) to its charging polarity, the toner charge is charged from plus to minus, quickly discharged from the charging roller, and simultaneously developed by the developing device. It can be recovered by cleaning.

The contact member 17 used a 100 μm polyimide film and contacted the charging roller 2 at a linear pressure of 10 (N / m) or less. Polyimide was used because it has a triboelectric charge property that gives a negative charge to the toner.
Further, in order to improve toner recoverability in the developing device, the absolute value of the non-exposure potential Vd and the value of Vback were set large. Specifically, the surface of the photoreceptor 1 was set to a uniform potential Vd = −800 V by setting the voltage applied to the charging roller to −1350 V. Further, by setting the developing bias to −300V, Vback = 500V was set.

[Developer carrier]
In the electrophotographic apparatus of the present invention, the developer carrying member carrying the developer has a role of contacting the image carrying member carrying the electrostatic latent image and developing the electrostatic latent image with the developer. Hereinafter, the developer carrier of the present invention will be described in detail with a developing roller as a typical form of the developer carrier.
As shown in FIG. 4, the developing roller has at least a conductive substrate, a conductive elastic layer, and an aluminum oxide film described later as a surface layer.

(Conductive substrate)
The material of the cored bar electrode 14a is not particularly limited as long as it is conductive, and can be appropriately selected from carbon steel, alloy steel, cast iron, and conductive resin. Examples of the alloy steel include stainless steel, nickel chromium steel, nickel chromium molybdenum steel, chromium steel, chromium molybdenum steel, nitriding steel to which Al, Cr, Mo and V are added.

(Conductive elastic layer)
FIG. 4 shows a developer carrier 14 used in Example 1 described later. The conductive elastic layer 14b1 contains at least a resin and conductive particles. The conductive elastic layer 14b1 is provided to give the developing roller the elasticity required in the apparatus to be used. As a specific configuration, either a solid body or a foam may be used. Further, the elastic layer may be a single layer or a plurality of layers. For example, the developer carrying member is always in pressure contact with the photosensitive member and the toner, and therefore an elastic layer having characteristics of low hardness and low compressive strain is provided to reduce mutual damage between these members. It is done.

(Conductive elastic layer material)
Examples of the material for the conductive elastic layer include the following. Urethane rubber, chloroprene rubber, isoprene rubber, butadiene acrylonitrile, epichlorohydrin rubber, ethylene propylene rubber, hydrin rubber fluoro rubber, natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene -One type selected from propylene rubber, chloroprene rubber, acrylic rubber, and the like, and a mixture of two or more thereof. In particular, urethane rubber, chloroprene rubber, butadiene acrylonitrile, epichlorohydrin rubber and the like can be mentioned as preferable materials. These can be used alone or in combination of two or more.

[Conductive particles]
Examples of the material of the conductive particles include the following. Conductive carbon such as carbon black and acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, color carbon subjected to oxidation treatment, pyrolytic carbon, indium doped tin oxide Metals such as (ITO), tin oxide, titanium oxide, zinc oxide, copper, silver, germanium, and conductive polymers such as metal oxide, polyaniline, polypyrrole, and polyacetylene. Moreover, there exists an ionic electroconductivity substance as an electroconductivity imparting agent, for example, the following can be mentioned. Inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, as well as modified fatty acid dimethylammonium ethosulphate, ammonium stearate acetate, laurylammonium acetate, octadecyltrimethylammonium perchloric acid Organic ionic conductive substances such as salt.

[Surface layer]
The surface layer includes (i) a chemical bond represented by the following formula (1),
(Ii) An aluminum oxide film having a chemical bond represented by the following formula (2-1) and at least one chemical bond selected from the group consisting of a chemical bond represented by the following formula (3-1) .

(In Formula (2-1), Formula (2-2) is a bidentate ligand, and X ¹ represents a carbon atom that forms a cyclic structure together with oxygen atoms in Al ³⁺ and the bidentate ligand. The number of the carbon atoms is 2 to 5, and at least one of the carbon atoms has an alkyl group having 1 to 18 carbon atoms as a substituent).

(In Formula (3-1), Formula (3-2) is a bidentate ligand, and X ² represents a carbon atom that forms a cyclic structure with Al ³⁺ and an oxygen atom in the bidentate ligand. The number of carbon atoms is 2 to 5, and at least one of the carbon atoms has an alkyl group having 1 to 18 carbon atoms as a substituent.
The number of carbon atoms forming a cyclic structure together with oxygen atoms in Al ³⁺ and the bidentate ligand is the shortest ring bonded between one oxygen atom coordinated to Al ³⁺ and another oxygen atom. It is the number of carbon atoms that form the formula structure, and is preferably 2 to 5 because of high coordination stability. Further, X ¹ and X ² are more preferably composed of three carbon atoms from the viewpoint of further stability of coordination.

In the case of a monodentate ligand or a tridentate or higher ligand, a skeleton that forms an oxygen octahedral structure is difficult to form. In order to assist the formation of an oxygen octahedral structure centered on stable aluminum (III) ions and to form a stable aluminum oxide film, it is necessary to be a bidentate ligand.
In addition, the number of bidentate ligands that assist in the formation of an oxygen octahedral structure centered on aluminum (III) ions is 1 as shown in Formula (2-1) or in Formula (3-1) It must be 2 as shown.

  The chemical bond represented by the formula (2-1) is preferably a chemical bond represented by the following formula (4). The chemical bond represented by the formula (3-1) is preferably a chemical bond represented by the following formula (5).

(In Formula (4), R < ¹ > -R < ³ > represents a hydrogen atom, an alkyl group, or an alkoxy group each independently, and at least ^{1 of} R < ¹ > -R < ³ > is a C1-C18 alkyl group. Represents).

(In Formula (5), R < ⁴ > -R < ⁶ > represents a hydrogen atom, an alkyl group, or an alkoxy group each independently, and at least 1 of R < ⁴ > -R < ⁶ > is a C1-C18 alkyl group. Represents).

It is preferable that the substituent which the carbon atom which forms a cyclic structure with the oxygen atom in Al3 ⁺ and a bidentate ligand has is a C1-C3 alkyl group.
When the substituent is an alkyl group having 1 to 3 carbon atoms, the solubility in alcohol as a solvent is sufficient, and the stability of the coating liquid and coating film is also sufficient. Further, since the ratio of the organic component to the Al atom is appropriate, the charge imparting ability to the toner does not decrease.

It is preferable that the decomposition temperature of the bidentate ligand is sufficiently higher than the temperature zone and the use temperature zone in the developing roller manufacturing process. This is because when the decomposition starts at a temperature lower than the upper limit value of these temperature zones, the formation of the oxygen octahedron structure centering on aluminum (III) ions cannot be sufficiently performed.
Specifically, the decomposition temperature of the bidentate ligand is preferably higher than 80 ° C, more preferably 150 ° C or higher.

[Aluminum oxide film]
The aluminum oxide film can be formed by preparing an alumina sol solution containing at least an aluminum alkoxide and a multidentate ligand and coating the surface of various developing rollers. Moreover, methods, such as a dipping method, a spray method, a ring method, can be used for the coating method.
After coating, heat treatment or UV irradiation may be performed as appropriate in order to improve the film formability of the aluminum oxide film.

[Aluminum alkoxide]
Examples of the aluminum alkoxide that can be used in the present invention include the following. Aluminum (III) n-butoxide, Aluminum (III) sec-butoxide, Aluminum (III) sec-butoxide bis (ethyl acetoacetate), Aluminum (III) t-butoxide, Aluminum (III) di-sec-butoxide ethyl acetoacetate, Aluminum (III) diisopropoxide ethyl acetoacetate, Aluminum (III) ethoxide, Aluminum hexafluoropentandionate, Aluminum (III) 3-hydroxy-2-methyl-4-pyronate, Aluminum (III) isopropoxide, Aluminum -9-octadecenyl acetoacetate diisopropoxide, aluminum (III) 2,4-pentandionate, aluminum phenoxide, aluminum (III) 2,2,6,6 butane dionate like to tetramethyl-3,5. These compounds may be used alone or in combination of two or more.

[Multidentate ligand]
Examples of the ligand coordinated to aluminum include β-diketones, β-ketoesters, salicylaldehydes, and the like. More specific examples of β-diketones include the following. Acetylacetone (2,4-pentanedione), propionylacetone (2,4-hexanedione), 2,4-heptanedione, 2,4-octanedione, 2,4-decanedione, 3,5-heptanedione, 2- Methyl-3,5-heptanedione, 2,2-dimethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, dipivaloylmethane (2,2,6,6-tetra Methyl-3,5-heptanedione), benzoylacetone (1-phenyl-1,3-butanedione), 1,3-diphenyl-1,3-propanedione, trifluoroacetylacetone (1,1,1-trifluoro-) 2,4-pentanedione), hexafluoroacetylacetone (1,1,1,5,5,5-hexafluoro-2,4-pentanedione) and the like.

More specific examples of β-ketoesters include the following. Methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, isopropyl acetoacetate, butyl acetoacetate, pentyl acetoacetate, octyl acetoacetate, decyl acetoacetate, dodecyl acetoacetate, octadecyl acetoacetate, ethyl 2-acetopropionate, 2-aceto Ethyl butyrate, ethyl 2-acetovalerate, ethyl propionyl acetate, ethyl 3-one-caproate and the like.
Specific examples of salicylaldehydes include the following. Examples include salicylaldehyde and 4-methoxysalicylaldehyde. In addition, 2-hydroxyphenyl ketone, 2-hydroxybenzoic acid ester and the like.

Example 1
The developing roller used in this example shown in FIG. 4 was produced as follows.
A conductive elastic layer 14b1 mixed with a conductivity-imparting agent is provided around a cored bar electrode 14a having an outer diameter of φ6 (mm), which is a conductive support, and the outer diameter of the developing roller 14 is φ11.5 (mm ). Here, as the material of the elastic layer 14b1, silicon rubber, urethane rubber, EPDM (ethylene / propylene copolymer), hydrin rubber, rubber mixed with these, or generally rubber can be used. In Example 1, the elastic layer 14b1 was formed by forming a silicon rubber layer of 2.5 mm and a urethane layer of 10 μm.

  Further, as the conductivity-imparting agent, a desired electric resistance value can be obtained by dispersing carbon particles, metal particles, ion conductive particles, and the like. In this example, carbon particles were used. Further, in order to adjust the hardness of the entire developing roller, a developing roller having a desired hardness was prepared by adjusting the amount of silicon rubber and the amount of silica as a filler.

Next, an alumina sol solution was prepared, and a surface layer 14b2 as an aluminum oxide film was formed to 2.1 μm by dipping on the elastic layer 14b1 described above.
The used alumina sol solution was prepared as follows.
Stir and mix aluminum-sec-butoxide (Al (O-sec-Bu) 3), which is an aluminum alkoxide, and isopropyl alcohol in a weight ratio of 1: 5,
The acetylacetone as a ligand is mixed so that the molar ratio with respect to the aluminum alkoxide is 0.5,
Stir at room temperature for 5 hours.

  In this example, the surface of the developing roller substrate was irradiated with UV before dipping, thereby improving the coating property and adhesion of the alumina sol solution. After forming the surface layer 14b2 of the aluminum oxide film, drying was performed at a temperature of 140 ° C. for 15 minutes.

<< Measurement of aluminum oxide film >>
The produced aluminum oxide film was analyzed by infrared spectroscopy (IR). Specifically, using an IR analyzer manufactured by Shimadzu Corporation, peaks 1598 cm ⁻¹ (attributed to C—O bond) and 1533 cm ⁻¹ (C) appearing when the ligands acetylacetone and aluminum alkoxide coexist. The analysis was carried out from the integrated intensity (assigned to -C bonds). First, in order to calculate the content of acetylacetone relative to aluminum, the change in the integrated peak intensity ratio relative to the blending ratio of the acetylacetone and aluminum alkoxide solution was measured, and a calibration curve was derived.

Using the above calibration curve, it was confirmed that the content ratio of acetylacetone relative to the aluminum atoms in this example was substantially equal to the stitch amount (input amount).
Further, even after the heat treatment at 200 ° C., which is sufficiently higher than the boiling point of acetylacetone 140 ° C., the above IR peak remains, and therefore, it is firmly bonded to aluminum (III), and the following formula (2- It was judged that the bond shown by 1) and (3-1) was formed.

Specifically, they are coordinated as in the following formulas (4) and (5), R ¹ , R ³ , R ⁴ and R ⁶ are methyl groups, and R ² and R ⁵ are hydrogen atoms. It was judged.

<< Measurement of hardness >>
(Average hardness of developing roller)
The Asker C hardness of the developing roller 14 was measured using an Asker-C hardness type spring type rubber hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) in accordance with Japan Rubber Association Standard SRIS0101 (1968). The measurement was performed 30 seconds after the contact with a force of 10 N, and the three longitudinal points were measured three times to obtain an average value for all. The measurement was carried out in the same environment by placing the measurement sample in an environment of a temperature of 23 ° C. and a relative humidity of 50% for 24 hours.
In the present embodiment, the developing roller 14 having an average hardness of 45 degrees to 70 degrees (Asker C) or less is preferably used. If the average hardness is 70 degrees (Asker C) or less, the toner is not easily melted by the rubbing of the developing roller 14, and it is difficult to cause blade fusion or roller fusion. Further, the contact state between the developing roller 14 and the photoreceptor 1 tends to be stable. If the average hardness is 45 degrees (Asker C) or more, permanent deformation due to compression set occurs, and use as the developing roller 14 does not become difficult.
In Example 1, the developing roller 14 having an average hardness of 55 degrees (Asker C) was used.

The volume resistance value of the developing roller 14 is preferably 2 × 10 ⁴ Ω to 5 × 10 ⁶ Ω. This is because if it is 2 × 10 ⁴ Ω or more, the current flowing through the elastic layer does not increase too much, and the necessary amount of current does not increase too much. Further, if it is 5 × 10 ⁶ Ω or less, the current flowing during development is not easily inhibited.
In Example 1, the one having a volume resistance value of 5 × 10 ⁵ Ω was used.

(Measurement method of volume resistance of developing roller)
A method for measuring the volume resistance of the developing roller 14 will be described.
FIG. 5 is a diagram illustrating a method for measuring the volume resistance of the developing roller 14 in the present embodiment.
As shown in FIG. 4, the developing roller 14 to be measured is a composite roller composed of a cored bar electrode 14a made of stainless steel, an elastic layer 14b1 formed on the outer periphery thereof, and a surface layer 14b2 formed on the outer periphery thereof. It has a layer structure. The width of the developing roller 14 in the longitudinal direction is about 230 mm.
In this measuring method, a cylindrical member G1 which is stainless steel of φ30 mm and rotates at a speed of about 48 mm / second in the direction of the arrow is used. When measuring the resistance, the developing roller 14 is driven to rotate as the cylindrical member G1 rotates.

An end roller (not shown) is fitted to the end of the developing roller 14 to restrict the amount of penetration into the cylindrical member 14 to 40 μm (in order to make the contact area between the developing roller 14 and the cylindrical member G1 constant). Is done. The end roller has a cylindrical shape. The outer diameter of the end roller is 80 μm smaller than the outer diameter of the developing roller 14.
F shown in FIG. 5 indicates a load applied to both ends of the developing roller 14 (both ends of the cored bar electrode 14a). In the measurement, the development is performed with a load of 500 g on one side and a load of 1 kg in total. The roller 14 is pressed toward the cylindrical member G1 side.

In addition, the measurement circuit G2 is used for this measurement method. The measurement circuit G2 includes a power source Ein, a resistor Ro, and a voltmeter Eout. In this measurement method, measurement was performed with Ein: 300 V (DC). A resistor having a resistance value of 100Ω to 10 MΩ can be used as the resistor Ro. Since the resistance Ro is for measuring a weak current, it is preferable to use a resistance value 10 ⁻² to 10 ⁻⁴ times the resistance of the developing roller 14 to be measured. That is, if the resistance value of the developing roller 14 is about 1 × 10 ⁶ Ω, the resistance value of the resistor Ro may be about 1 kΩ.
When this measuring circuit G2 is used, the resistance value Rb of the developing roller 14 is calculated by the following equation (Equation 1). In addition, Eout measured the value 10 seconds after applying a voltage.
(Equation 1) Rb = Ro × (Ein / Eout−1) [Ω]
The average film thickness of the surface layer in Example 1 was 2.1 μm.

Next, the cause of fogging in a high humidity environment is described. The occurrence of fog is mainly caused by the loss of toner charge at the contact portion (development nip portion) between the developing roller 14 and the photosensitive member 1, and the toner cannot be controlled by the electric field. Is thought to be due to metastasis.
To verify fog, turn off the main body power during solid white paper, measure the toner charge amount distribution on the developing roller, and each developing roller before and after passing through the developing nip where the photosensitive member and the developing roller contact each other This was done by measuring the charge amount distribution of the above toner and evaluating the amount of change.

FIG. 6 is a graph showing the charge amount of the toner coat layer on the developing roller 14 before and after passing through the developing nip portion in Example 1 and Comparative Example 1.
The vertical axis in FIG. 6 indicates the frequency of toner. The total number of toners counted was 3,000 before and after passing through the development nip.
The horizontal axis in FIG. 6 represents Q / d [fC / μm]. Q is the charge amount of one toner and d is the toner particle diameter, which were measured with an E-SPART analyzer manufactured by Hosokawa Micron Corporation. The toner charge amount is attenuated particularly when the strength of the electric field formed between the photosensitive member and the developing roller is larger, and the toner charge amount is attenuated and the fog amount is increased. Similarly to the electric field strength, the slower the process speed, the more the toner charge attenuation amount increases and the fogging amount increases. The reason is that the time when the toner on the developing roller passes between the developing nip portions where the photosensitive member and the developing roller are in contact with each other is increased, and the toner charge is further attenuated.
The lower part of FIG. 6 shows the charge amount distribution on the developing roller before and after passing through the developing nip when the developing roller of Comparative Example 1 described later is used. In Comparative Example 1, it can be seen that the charge amount of the toner is greatly reduced after passing through the developing nip portion than before passing.

(Comparative Example 1)
The comparative example 1 will be described with respect to differences from the first embodiment. The developing roller used in Comparative Example 1 was produced as follows.
A conductive silicon rubber layer in which a conductivity-imparting agent is blended is provided around a cored bar electrode 14a having an outer diameter of φ6 (mm), which is a conductive support, and the silicon rubber layer is coated with rough particles and a conductive layer as a coating layer. The urethane resin in which the property-imparting agent was dispersed was coated with 10 μm. The outer diameter of the entire developing roller 14 having the elastic layer 14b1 formed by coating the silicone rubber layer with urethane resin was φ11.5 (mm).
The resistance value of the developing roller was about 10 ⁵ Ω, and the average hardness (Asker C) was 55 degrees.

(Comparative Example 2)
About the comparative example 2, a different point from Example 1 is described. The developing roller used in Comparative Example 2 was produced as follows.
A conductive silicon rubber layer containing a conductivity-imparting agent was provided around a cored bar electrode 14a having an outer diameter of φ6 (mm), which is a conductive support. As a coating layer, 10 μm of a urethane resin in which rough particles and a conductivity-imparting agent are dispersed is coated. The outer diameter of the entire developing roller 14 having the elastic layer 14b1 formed by coating the silicone rubber layer with urethane resin was φ11.5 (mm).

Next, a colloidal alumina solution was prepared, and the developing roller base having the elastic layer 14b1 was dipped into the colloidal alumina solution to form an alumina surface layer 14b2 having a thickness of 1.5 μm. Here, the colloidal alumina solution used was prepared by stirring and mixing an alumina sol solution 520 (volume average particle size 20 nm, boehmite) manufactured by Nissan Chemical and ethanol so that the volume ratio was 1: 4.
After forming the alumina surface layer 14b2, drying was performed at a temperature of 140 ° C. for 15 minutes. The resistance value of the developing roller was about 10 ⁶ Ω, and the average hardness (Asker C) was 55 degrees.

(Example 2)
About Example 2, the difference from Example 1 is that 3-methyl-2,4-pentanedione was used as a polydentate ligand. In the same manner as in Example 1, it was confirmed from the IR calibration curve that the content ratio of 3-methyl-2,4-pentanedione with respect to aluminum atoms was substantially equal to the stitch amount.

(Example 3)
Example 3 differs from Example 1 in that ethyl acetoacetate was used as the polydentate ligand. In the same manner as in Example 1, it was confirmed from the IR calibration curve that the content ratio of ethyl acetoacetate with respect to aluminum atoms was substantially equal to the stitch amount.

<< Evaluation method >>
Below, the evaluation method in Embodiment 1 is described.

(Measurement of charge amount)
The toner charge amount was measured by the above-mentioned E-SPART analyzer manufactured by Hosokawa Micron Co., Ltd. and calculated by the average Q / d [nC / μm]. The measurement was carried out in a high-humidity environment (temperature 30 ° C., relative humidity 80%) and a low-humidity environment (temperature 15 ° C., relative humidity 10%), and after standing for 24 hours after printing was completed. The printing test was performed by continuously passing a horizontal line of recorded images having an image ratio of 5%. Here, as the horizontal line with an image ratio of 5%, specifically, an image in which 19-dot line non-printing is repeated after 1-dot line printing is used.

(Evaluation of initial fog and fog after endurance in high humidity environment)
The fog is an image defect that appears slightly as a background stain when the toner is slightly developed in a white portion (unexposed portion) that is not originally printed. The fog amount was evaluated as follows.
While printing a solid white image, the electrophotographic apparatus is stopped. After development, the toner on the photoconductor before transfer is once transferred to a transparent tape, and the tape with the toner attached thereto is attached to a recording paper or the like. Also, a tape to which no toner is attached is attached to the same recording paper at the same time. From the top of the tape affixed to the recording paper, the optical reflectivity is measured by a green filter with an optical reflectometer (TC-6DS manufactured by Tokyo Denshoku). The reflectance amount of fog was determined by subtracting from the rate and evaluated as the amount of fog. The fog amount was measured at three or more points on the tape and the average value was obtained.

A: The fog amount is less than 1.0%.
B: The fog amount is 1.0% or more and less than 3.0%.
C: The fog amount is 3.0% or more and less than 5.0%.
D: The fog amount is 5.0% or more.

The fog evaluation was carried out in an environment of a temperature of 30 ° C. and a relative humidity of 80%, and after leaving 100 sheets and 5000 sheets, after standing for 24 hours. The printing test was performed by continuously passing a horizontal line of recorded images having an image ratio of 5%. Here, as the horizontal line with an image ratio of 5%, specifically, an image in which 19-dot line non-printing is repeated after 1-dot line printing is used. Further, continuous paper feeding was performed at a normal speed (120 mm / second), and fogging evaluation was performed in a low speed mode (60 mm / second).
Further, the image evaluation after 100 sheets passed was set as the initial image evaluation after 5000 sheets and after endurance (after long-term use).

(Evaluation of initial fog and low fog after durability in low humidity environment)
This evaluation method basically uses the same evaluation criteria as described above, but differs in the following points.
This fog evaluation was performed in an environment of a temperature of 15 ° C. and a relative humidity of 10%, and after standing for 100 sheets and 5000 sheets, after standing for 24 hours. Further, continuous paper feeding and fogging evaluation were performed at a normal speed (120 mm / second).
Also, the image evaluation after 100 sheets passed was set as the initial image evaluation after 5000 sheets after the endurance.

(Evaluation of solid density difference)
The solid density difference evaluation was performed after 100 sheets were printed after the electrophotographic apparatus was allowed to stand for 24 hours in an environment of a temperature of 15 ° C. and a relative humidity of 10%, and adapted to the environment. The printing test for 100 sheets was performed by continuously passing a horizontal line recorded image having an image ratio of 5%. For the image evaluation, one solid black image was output, and the density difference between the output leading edge and the trailing edge of the solid image was obtained using a Spectrodensitometer 500 (manufactured by X-Rite) and evaluated based on the following criteria. The print test and the evaluation image were monochromatic and were output at a normal paper speed (120 mm / second).
A: Density difference between paper leading edge and paper trailing edge is less than 0.1 B: Density difference between paper leading edge and paper trailing edge is 0.1 or more and less than 0.2 C: Density between paper leading edge and paper trailing edge The difference is 0.2 or more

Below, the evaluation method in Embodiment 2 is described.
(Evaluation of initial fog at cleanerless)
This evaluation conforms to the initial fog evaluation in the first embodiment.

(Initial halftone density evaluation when cleaner is not used)
In this evaluation, the electrophotographic apparatus was allowed to stand for 24 hours in an environment of a temperature of 30 ° C. and a relative humidity of 80%. The printing test for 100 sheets was performed by continuously passing a horizontal line recorded image having an image ratio of 5%. The image evaluation was performed by printing one halftone image. Next, 20 sheets of vertical band images having a width of 2 cm were continuously passed, and the halftone image density was printed on the 21st sheet by continuous passing. And it evaluated according to the following references | standards. The print test and the evaluation image were monochromatic and were output at a normal paper speed (120 mm / second).

A: In the halftone images of the first and 21st sheets, the density difference cannot be recognized visually.
B: The density difference can be visually recognized in the first and 21st halftone images.
In this evaluation, the halftone image means a striped pattern in which one line in the main scanning direction is recorded and then four lines are not recorded, and the halftone density is expressed as a whole.
Hereinafter, each evaluation result is shown in Table 1.
Table 1 (b) shows the results of the evaluation performed with the process cartridge described as the first embodiment, and Table 1 (c) shows the results of the evaluation performed with the process cartridge described as the second embodiment. In Tables 1 and 2, “HH” means an environment having a temperature of 30 ° C. and a relative humidity of 80%, “LL” means an environment having a temperature of 15 ° C. and a relative humidity of 10%, and “HT” is an intermediate value. Means halftone.

<< Comparison between Example 1-1 and Comparative Example 1-1 >>
First, the superiority of the present invention over Comparative Example 1-1, which is the prior art, will be described. In the evaluation results in Embodiment 1, Comparative Example 1-1 shows an increase in the amount of fog after endurance in a high humidity environment. The reason for this is considered that the toner deterioration has progressed and the fog amount has increased as the chargeability of the toner has decreased.
On the other hand, in Example 1-1 which is the present invention, the amount of fog is suppressed even after the durability test. The reason for this is that even when the toner deterioration progresses and the charge amount of the toner decreases, the aluminum oxide film of the present invention has a high negative charge imparting property to the toner. The increase can be remarkably suppressed.

<< Comparison between Example 1-2 and Comparative Example 1-2 >>
Next, the evaluation result in Embodiment 2 will be described. Since this embodiment does not have a cleaning blade, the toner that remains on the photosensitive member without being transferred is negated when it passes through the charging roller, and is set so as to be collected by the developing device at the developing nip portion. It is. Further, in this example, Vback is set to a large value of 500 V in order to improve the return toner recovery performance at the development nip. In Comparative Example 1-2 in the second embodiment, Vback is large, so that the toner charge is attenuated when passing through the developing nip portion, and a slight increase in the fog amount is observed from the beginning.

  Further, in Comparative Example 1-2, since the charge amount of the toner is low, in addition to the increase of the fog amount, the amount of toner remaining without being transferred is large. The reason why the transferability is lowered is considered to be that when the charge amount of the toner is small, the amount of toner that cannot be electrically controlled increases, so that the toner cannot be transferred and tends to remain on the photoreceptor. Toner remaining on the photoconductor without being fogged or transferred reaches the contact portion between the charging roller and the photoconductor, but when the amount of toner reached is large, the amount of toner accumulated on the surface of the charging roller increases, so-called Toner contamination occurs and the desired charging performance cannot be maintained. As a result, the charging potential changes, causing a change in halftone image density.

On the other hand, in Example 1-2 which is the present invention, a good image can be obtained also in the second embodiment. The reason is that the aluminum oxide surface layer in the present invention has a high resistivity, so that the toner charge attenuation and fog increase are effectively suppressed even in the state where the Vback is large and the toner is easily attenuated in the developing nip portion. Can do. On the other hand, in the present invention, since the average resistance of the developing roller has an appropriate resistance value of 2 × 10 ⁴ Ω to 5 × 10 ⁶ Ω, it suppresses toner charge attenuation while maintaining developability. By doing so, a good image can be stably obtained.

  Furthermore, in the present invention, appropriate charge can be imparted to the toner at the same time, so that in addition to suppressing the amount of fog toner, high transferability can be obtained. The reason for the high transferability is that in the case of a toner having an appropriate charge, the transfer force is excellent in controllability of electric force. By suppressing the amount of fog and the amount of toner remaining without being transferred, toner contamination on the surface of the charging roller is remarkably reduced, so that a good halftone image density can be obtained.

  As described above, in the present invention, a stable and good image can be obtained in any of the embodiments. In the cleanerless system as in the second embodiment, the image cannot be transferred onto the photoreceptor. Since the amount of residual toner can be remarkably suppressed, charging roller contamination can be suppressed. In order to improve the recoverability, the amount of fogging can be suppressed even when Vback is set to a large value, so that the toner remaining without being transferred can be effectively recovered in the developing device.

<< Comparison between Example 1 and Comparative Example 2 >>
Comparative Example 2 is an example in which colloidal aluminum oxide having charge imparting properties and insulating properties was formed, as in the present invention. First, the evaluation results in a high humidity environment are described.
The initial fog evaluation results in a high-humidity environment are good for both Comparative Examples 2-1 and 2-2. However, after endurance, the amount of fogging in a high humidity environment increases. In the colloidal aluminum oxide layer formation of Comparative Example 2, the binding due to the cohesive force of the colloidal particles is dominant.

  Originally, in order to reinforce the bonding strength of the layer formed of colloidal particles, high temperature treatment is required. However, when formed on an elastic body of an organic material as in the present invention, high temperature treatment becomes difficult. . As a result, the layers were formed by low-temperature treatment as in Comparative Examples 2-1 and 2-2, and the binding force due to the cohesive force of the colloidal particles was dominant, and the external force (contact with the photoreceptor, contact with the regulating member) Since the cracking and scraping are promoted by contact and contact with the supply member, the durability of the film is low. In addition, in the developing roller (developer carrier) of the present invention, the Asker C hardness is 45 to 70 degrees in order to stably contact each contact body and to suppress excessive toner deterioration. Is set.

  Therefore, each contact portion repeats microdeformation on the surface of the developing roller, but the surface layer made of colloidal particles as in Comparative Examples 2-1 and 2-2 does not have the flexibility to follow the deformation, so it cracks. And sharpening is promoted. Therefore, in the second half of the endurance (after a long period of use), the charge imparting property to the toner is lowered and the resistance is reduced by cracking, which causes a remarkable increase in the amount of fogging. The amount of fog increases. On the other hand, in Example 1, an increase in the amount of fog is suppressed regardless of the first and second embodiments.

  The present invention uses a multidentate ligand that is easily coordinated to an aluminum (III) ion. Therefore, at the same time that a strong bond to aluminum (III) ions is generated, flexibility can be obtained by the organic component of the multidentate ligand, and the followability to microdeformation on the surface of the developing roller is high. As a result, flexibility can be imparted at the same time as strengthening the bonding of the aluminum oxide film, the durability of the film can be improved, and the increase in the amount of fog after durability is remarkably suppressed. In particular, it can be seen that, even at the time of high Vback as in the second embodiment, the increase in the amount of fog is suppressed, so that the decrease in surface resistance due to cracks and the like is effectively suppressed.

Further, as a verification, the microhardness of the aluminum oxide film of Comparative Example 2 and the aluminum oxide film of Example 1 was measured. For measurement of micro hardness, TriboScope manufactured by HYSITRON was used. Measurement conditions were calculated from the change in load by displacing the Belkovic indenter (tip R150 nm) from no load to the maximum load in 5 seconds, and maintaining the state from the maximum load to no load in 5 seconds. The maximum load at this time was the load amount when 10% of the average film thickness of the surface layer was displaced.
The micro hardness of the aluminum oxide film of Example 1 was confirmed to be lower than the micro hardness of the aluminum oxide film of Comparative Example 2.

In addition, when the thickness of the aluminum oxide film after printing a predetermined number of sheets is measured from the SEM cross section and the film thickness reduction rate is calculated, the film thickness reduction rate of Example 1 is suppressed more than the film thickness reduction rate of Comparative Example 2. Therefore, it is considered that the flexibility of the film is improved.
On the other hand, due to the presence of the organic component of the multidentate ligand, it is conceivable that the properties of imparting charge to the negative toner and the high resistance inherent in the aluminum oxide are inhibited or reduced. However, since the characteristics of aluminum oxide are maintained in the multidentate ligand used in the present invention, a stable and good image can be obtained.

  The reason is considered to be the following factors. Commonly known highly insulating aluminum oxide is α-alumina, boehmite, or the like. In these crystal systems, six oxygen atoms are bonded around aluminum (III) ions to form an octahedral structure of oxygen centering on aluminum (III) ions. I believe you can get However, in order to form such a crystal system, a high temperature treatment that damages the organic elastic body is required.

On the other hand, it is considered that the polydentate ligand used in the present invention assists the formation of an oxygen octahedral structure centered on aluminum (III) ions during low-temperature treatment. Therefore, even if an organic component such as a ligand is mixed, the charge imparting property and high resistance to the negative toner, which are inherent characteristics of aluminum oxide, can be obtained. For the above verification, ²⁷ Al-NMR measurement of the aluminum sol solution used in Example 1 was performed.

  As a result, the aluminum sol solution without a ligand has 4, 5, and 6 bonded atoms around Al, but the aluminum sol solution used in Example 1 has approximately the bonded number of atoms around Al. 6. From this, the role of the polydentate ligand is to assist in the formation of an oxygen octahedral structure centered on aluminum (III) ions, and to maintain the charge imparting property and high resistance to the original negative toner of aluminum oxide. It is thought that there is.

  As described above, the ligand decomposition temperature is preferably 150 ° C. or higher. The ligand used in Example 1 was confirmed to be partially desorbed and decomposed at 200 ° C. from a heat test and a decrease in the absorption peak of the ligand that absorbs infrared rays. That is, it was confirmed that the ligand used in the present invention sufficiently assists the formation of an oxygen octahedron structure centered on aluminum (III) ions in the developing roller manufacturing process.

In addition, a vibration peak derived from keto-enol of the carbonyl group was observed by measuring an infrared absorption spectrum, and it was confirmed that the ligand formed a coordination structure.
As described above, in the present invention,
-The coordination structure formed by the multidentate ligand and the aluminum (III) ion can provide charge imparting properties and high resistance to the original negative toner of aluminum oxide, and
-Increased binding strength between polydentate ligands and aluminum (III) ions and flexibility of organic components contained in multidentate ligands improves the binding strength and flexibility of aluminum oxide films, resulting in wear resistance And good image formation can be performed even after durability.
Next, the evaluation results in a low humidity environment are described.

  In Comparative Example 2, there is a density difference between the leading edge and the trailing edge of the solid image. This reason is considered to be because the charge imparting property to the toner is very high in a low humidity environment as shown in Table 1. For details, we infer the following mechanism. When the charge amount of the toner is high, it becomes difficult to peel off the toner on the developing roller with a physical force. For this reason, the charge on the toner coat layer is changed between the state where the toner on the developing roller is not consumed, such as during non-printing, and the state where the toner on the developing roller is consumed. A difference occurs in the amount and the coating amount, and a difference occurs in the amount of toner developed on the photoreceptor. As a result, it is considered that there is a difference in density between the leading edge of the solid image (for the first round of the developing roller) and the trailing edge of the solid image (for the second and subsequent rounds of the developing roller), resulting in an image defect.

  Further, in Comparative Example 2, the amount of fogging after endurance increases compared to Comparative Example 1. This is also because the charge amount of the toner is high. As described above, when the charge amount of the toner is large, the toner on the developing roller is difficult to physically peel off. For this reason, the toner remaining on the developing roller is acceleratedly deteriorated due to the rubbing of each contact member. As a result, deposits and fused products due to the toner component are deposited on the developing roller. As a result, a film having the same charge polarity is generated, the charge imparting to the toner is remarkably inhibited, a toner having a small charge amount is generated, and the fog amount is increased.

  The reason why the toner charge amount is large in the low humidity environment in Comparative Example 2 will be described. Since colloidal aluminum oxide can be easily coated on the surface layer, it is relatively easy to form the surface layer. However, colloidal aluminum oxide is a hydrate of aluminum oxide called boehmite, and a colloidal solution can be obtained from the nature that it is easily compatible with water. On the other hand, the property of being easily adapted to water remains as it is in the low-temperature treatment, so that the aluminum oxide film in Comparative Example 2 has high hygroscopicity. Therefore, the charge imparting ability is equivalent to that of the present invention in a high humidity environment, but the charge imparting ability to the negative toner is remarkably increased in a low humidity environment because the influence of moisture desorption is large. As a result, there is a density difference between the leading edge and the trailing edge of the solid image.

  On the other hand, in the present invention, it is considered that the influence of moisture adsorption / desorption is suppressed by using a hydrophobic multidentate ligand. By coordinating the multidentate ligand to the aluminum alkoxide, there is a function of suppressing water reaction, that is, hydrolysis and condensation reaction. Since the aluminum sol liquid used in the present invention is stable for a long period of time, the reaction with moisture in the air is suppressed. When there is no multidentate ligand, the aluminum sol solution reacts with moisture in the air, and becomes cloudy and settles. Since moisture adsorption is suppressed even after the aluminum oxide film is formed, a stable charge amount from a high humidity environment to a low humidity environment is obtained as shown in Table 1, and the difference in charge amount between the environments is also reduced. Yes. As a result, it is possible to suppress the toner charge amount from becoming too high and to obtain a stable and stable image even in a low humidity environment.

<< Comparison of Examples 1 to 3 >>
Furthermore, the superiority in the present invention will be described by comparing the examples.
In Examples 1 to 3, the evaluation results under a high humidity environment are stable and good. In Example 1 in a low-humidity environment, an increase in the amount of fog after endurance and a slight difference in density between the leading edge and the trailing edge of the initial solid image occur.
The reason for this is considered to be that the charge imparting property of the toner in the low humidity environment is higher in Example 1 than in Examples 2 and 3 as shown in Table 1. As a result, although not as much as Comparative Example 2, it is considered that a slight image defect occurs in a low humidity environment. The reason why the environmental fluctuation of Example 1 is large compared to Examples 2 and 3 is presumed to be because the hydrophobicity of the ligand used is slightly lower. The ligands used in Examples 2 and 3 are both more hydrophobic than the ligand used in Example 1, and the difference in the average value of the toner charge amount in a high and low humidity environment. Is considered small. As a result, in Examples 2 and 3, a stable and stable image from high humidity to low humidity could be obtained.
As described above, in the present invention, stable images from high humidity to low humidity can be obtained by using a highly hydrophobic ligand.
Next, the content ratio of the ligand to the aluminum (III) ion will be described.

(Examples 4 to 7)
The same procedure as in Example 2 was performed except that methylacetylacetone (3-methyl-2,4-pentanedione), which is a ligand, was mixed so that the molar ratio with respect to aluminum alkoxide was as shown in Table 2.
In Examples 4 to 7, as in Example 1, it was confirmed from the IR calibration curve that the content ratio of 3-methyl-2,4-pentanedione with respect to aluminum atoms was almost equal to the stitch amount.

<< Evaluation method >>
(Evaluation of initial fog and fog after endurance in high humidity environment)
This evaluation method conforms to the initial fogging and post-durability fogging evaluation in the high humidity environment in the first embodiment.
(Evaluation of initial fog and low fog after durability in low humidity environment)
This evaluation method is in accordance with the initial fogging and post-durability fogging evaluation in the low-humidity environment in the first embodiment.
The evaluation results are shown in Table 2 below.

<< Evaluation results >>
In Examples 4 and 7, a slight increase in the amount of fog occurs. In Example 4, the amount (molar ratio) of the ligand to the aluminum (III) ion is as small as 0.1. When the number of ligands is reduced, the function of assisting the formation of an oxygen octahedral structure centered on aluminum (III) ions is reduced, and the binding power and flexibility of the aluminum oxide film are reduced along with a decrease in charge imparting ability. It is considered that cracks and the like occur after durability. After the endurance, the amount of fogging slightly increased particularly in a high humidity environment where the toner deterioration progresses and the toner charging ability decreases.

  On the other hand, in Example 7, although the ligand was sufficiently mixed with 1.7 mol with respect to the aluminum (III) ion, the fog amount increased in the high and low humidity environments after the endurance. did. The reason is considered to be that the nature of the ligand itself has become apparent. In a high humidity environment, it is considered that the amount of fogging increased after the endurance as a result of an increase in the ligand ratio and a decrease in the ability to impart charge to the toner.

On the other hand, in a low-humidity environment, it is considered that the adhesion force increased due to an increase in the ligand ratio, resulting in toner contamination and external additive contamination. When toner contamination or external additive contamination progresses, the chargeability changes to the same polarity as that of the toner base, so that the negative charge imparting property to the toner is lowered and the fog amount is considered to be slightly increased.
On the other hand, Examples 2, 5, and 6 were able to obtain stable and stable images from high humidity to low humidity.
In Examples 2, 5, and 6, since the ligand is in an appropriate ratio of 0.3 to 1.5 mol with respect to the aluminum (III) ion, it is considered that stable and good images could be obtained. .

1: Photosensitive member 2: Charging roller 3: Laser optical device 4: Developing device 5: Primary transfer device 6: Intermediate transfer member 7: Secondary transfer device 8: Paper 9: Cleaning blade 10: Fixing device 11: Cartridge 12: Toner 13: developing container 14: developing roller 14a: cored bar electrode 14b1: elastic layer 14b2: surface layer 15: supply roller 15a: cored bar electrode 15b: urethane foam layer 16: regulating blade

Claims (11)

A developer carrier having a base, an elastic layer and a surface layer in this order,
The surface layer is
(I) a chemical bond represented by the following formula (1);
(Ii) An aluminum oxide film having a chemical bond represented by the following formula (2-1) and at least one chemical bond selected from the group consisting of a chemical bond represented by the following formula (3-1) A developer carrier characterized by:
(In Formula (2-1), Formula (2-2) is a bidentate ligand, and X ¹ represents a carbon atom that forms a cyclic structure together with oxygen atoms in Al ³⁺ and the bidentate ligand. The number of carbon atoms is 2 to 5, and at least one of the carbon atoms has an alkyl group having 1 to 18 carbon atoms as a substituent).
(In Formula (3-1), Formula (3-2) is a bidentate ligand, and X ² represents a carbon atom that forms a cyclic structure with Al ³⁺ and an oxygen atom in the bidentate ligand. The number of carbon atoms is 2 to 5, and at least one of the carbon atoms has an alkyl group having 1 to 18 carbon atoms as a substituent). The developer carrier according to claim 1, wherein the chemical bond represented by the formula (2-1) is a chemical bond represented by the following formula (4):
(In Formula (4), R < ¹ > -R < ³ > represents a hydrogen atom, an alkyl group, or an alkoxy group each independently, and at least ^{1 of} R < ¹ > -R < ³ > is a C1-C18 alkyl group. Represents). The developer carrier according to claim 1 or 2, wherein the chemical bond represented by the formula (3-1) is a chemical bond represented by the following formula (5):
(In Formula (5), R < ⁴ > -R < ⁶ > represents a hydrogen atom, an alkyl group, or an alkoxy group each independently, and at least 1 of R < ⁴ > -R < ⁶ > is a C1-C18 alkyl group. Represents).   The developer carrier according to claim 1, wherein the substituent of the carbon atom contained in the atomic group is an alkyl group having 1 to 3 carbon atoms.   The developer carrying member according to any one of claims 1 to 4, wherein a decomposition temperature of the bidentate ligand is 150 ° C or higher.   The developer carrier according to claim 1, wherein a content ratio of the bidentate ligand to the aluminum atom in the aluminum oxide film is 0.3 to 1.5.   The developer carrier according to claim 1, wherein the developer carrier is a developer carrier capable of charging one-component negatively chargeable toner.   The developer carrying member according to claim 1, wherein the developer carrying member has an Asker C hardness of 45 to 70 degrees. The developer carrier according to claim 1, wherein the developer carrier has a volume resistance value of 2 × 10 ⁴ Ω to 5 × 10 ⁶ Ω.   A developing unit having the developer carrying member according to any one of claims 1 to 9, and at least one unit selected from the group consisting of an electrophotographic photosensitive member and a charging unit are integrally supported, and an electron A process cartridge which is detachable from a main body of a photographic apparatus. An electrophotographic apparatus comprising: a developing unit having the developer carrying member according to claim 1, an electrophotographic photosensitive member, a charging unit, an exposure unit, and a transfer unit.