JP2002268371A - Developing unit and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing unit, which simultaneously satisfies toner releasability and wear resistance of developing roller, enables obtaining a stable thin layer of toners and to obtain images of high image quality which are freely of after-images and an imaging device. SOLUTION: The developing unit 22 of the imaging device is a one-component developing unit 22, which has the developing roller 40 for conveying the toners into an image carrying member 12 by moving, while transporting the toners on its surface and a deposition thickness regulating member 44 for regulating the deposition thickness of the toners by abutting against the developing roller 40 across the toners deposited on the developing roller 40 and visualizes the latent image on the image transporting member 12 by the toners transported by the developing roller 40. At least the surface of the developing roller 40 comprises a material, containing a polyimide denatured silicone resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component developing apparatus and an image forming apparatus used for an image forming apparatus such as a copying machine, a facsimile, a printer, and the like.

[0002]

2. Description of the Related Art A so-called electrophotographic image forming apparatus performs printing by the following process.

That is, the surface of the photoreceptor is uniformly charged by a charging device, and an electrostatic latent image based on image information by an optical system is formed on the surface. Next, when the electrostatic latent image passes through a position facing the developing device, the latent image is visualized by toner adhesion, is superimposed on a recording material that is conveyed in a timely manner, and is transferred using a transfer device. Then, the toner image is transferred to the recording material. The transferred toner image is fixed on the recording material by passing through a fixing device. On the other hand, the photoreceptor after the transfer process has the residual toner removed by the cleaning device, and the residual charge on the photoreceptor is discharged by the discharging device.

[0004] As one of the developing devices used in such an image forming apparatus, a one-component developing system using one-component toner is generally used.

A typical example of the one-component developing system will be described.

First, a one-component toner triboelectrically charged at a contact portion between a developing roller and a replenishing roller rotating in the same direction or in the opposite direction while being pressed against the developing roller with a predetermined bite amount is supplied to the developing roller and the replenishing roller. Adheres to the developing roller due to the sliding friction of. Further, the one-component toner adhering to the developing roller is further frictionally charged at a contact portion between the developing roller and a thin layer forming member provided in contact with the surface of the developing roller, and the thickness of the toner layer is regulated. ,
A uniform thin toner layer is formed on the developing roller. The thin toner layer is supplied to the photoconductor while being held by the developing roller. Thereafter, at the opposing portion between the developing roller and the photoconductor, the one-component toner supplied from the developing roller is developed by being attracted to an electrostatic latent image on the photoconductor surface due to a potential difference between the developing roller and the photoconductor, and developed. Imaged.

The one-component developing systems are broadly classified into a contact developing system and a non-contact developing system according to the contact state between the developing roller and the photosensitive member.

In the case of the former method, it is particularly necessary to impart flexibility to one or both structures or materials in order to stably contact the developing roller and the photosensitive member. For this reason, an endless or endless belt has been used as the photosensitive member, and a flexible material or structure such as rubber or sponge has been used as the developing roller.

However, from the viewpoint of apparatus cost, the use of a drum as a photoreceptor can reduce the cost more than the use of a belt. Therefore, it has been required to impart more flexibility to the developing roller.

Since the surface member of the developing roller used in the developing device is always in contact with the toner, it is required to have excellent releasability from the toner and abrasion resistance with little deterioration in physical properties. Conventionally, several materials have been proposed. Have been.

As an example of using a material excellent in abrasion resistance, a resin in which carbon fibers are dispersed and reinforced (JP-A-61-231)
No. 71), an example in which a glass powder is contained in a ceramic paint (Japanese Patent Application Laid-Open No. 4-75568), a silicone rubber containing a specific silica (Japanese Patent Application Laid-Open No. 9-292768), and an example in which the surface is coated with polyamide ( JP-A-6-14
Many materials have been proposed.

An example in which a phenolic resin surface coating film containing conductive carbon and graphite is formed (Japanese Patent Laid-Open No. 3-12676) as an improved mold release property, Examples using a coupling agent (JP-A-4-19761), examples containing a fluorine-based surfactant (JP-A-4-22979), and examples using a solid lubricant (JP-A-8-21726). Gazette).

As an example in which both characteristics are to be solved, an example in which a crystalline and an amorphous polyamide resin are mixed (Japanese Unexamined Patent Publication No.
-247478).

[0014]

However, in the above-mentioned prior art, those having excellent toner releasability have a surface for preventing the toner from being fixed by gradually abrading the surface. It was difficult to balance the characteristics.

[0015] The present invention is intended to solve these problems which cannot be solved by the conventional techniques.

That is, a first object of the present invention is to provide a developing unit and an image forming apparatus which simultaneously satisfy the toner releasing property and abrasion resistance of a developing roller and can obtain a stable thin toner layer. .

It is a second object of the present invention to provide a developing unit and an image forming apparatus capable of obtaining a high-quality image without an afterimage.

It is a third object of the present invention to provide a high quality and high durability image forming apparatus.

[0019]

According to a first aspect of the present invention, there is provided a developing unit comprising: a developing roller which moves while carrying toner on a surface thereof and conveys the toner onto an image carrier; A carrying-thickness regulating member (thin-layer regulating member) that abuts on the developing roller via the toner carried on the developing roller and regulates the carrying thickness of the toner. In a one-component developing unit for visualizing a latent image on the image carrier using a toner, at least the surface of the developing roller is made of a material containing a polyimide-modified silicone resin.

According to the first aspect of the present invention, by using a polyimide-modified silicone resin having excellent releasability and abrasion resistance on the surface of the developing roller, toner sticking does not occur and abrasion resistance is reduced. By virtue of this, it is possible to obtain a developing unit in which the chargeability and uniformity of the thin layer of the toner are stable.

Further, the invention of the developing unit according to claim 2 is as follows.
The developing roller includes a plurality of layers, at least a surface layer of which is made of a material containing the polyimide-modified silicone resin, and a layer other than the surface layer having an elastic layer.

According to the second aspect of the present invention, especially when the photosensitive member is a drum, the developing roller can be provided with flexibility and a developing nip necessary for contact developing can be secured, and stable contact developing can be achieved. A developing unit that can be used can be obtained.

Further, the invention of the developing unit according to claim 3 is as follows.
The volume resistance of the portion composed of the material containing the polyimide-modified silicone resin is 10 ¹² Ω · cm or less. Here, the portion composed of the material containing the polyimide-modified silicone resin refers to the surface or surface layer composed of the material containing the polyimide-modified silicone resin or the inner or inner layer composed of the material containing the polyimide-modified silicone resin. .

According to the third aspect of the present invention, there is provided a developing unit capable of providing a high quality image by eliminating the triboelectric charge existing in the vicinity of the developing roller surface after the development, and eliminating the afterimage caused by the residual charge. Obtainable.

Further, the invention of the developing unit according to claim 4 is as follows.
The site composed of the material containing the polyimide-modified silicone resin may be one or both of a quaternary ammonium salt-containing maleimide resin and a quaternary ammonium base-containing methacrylimide resin, with respect to 100 parts by mass of the polyimide-modified silicone resin. It is characterized by containing not less than parts by mass.

According to the above construction of the fourth aspect of the present invention, it is possible to obtain a developing unit which not only can uniformly control the resistance but also can control the toner charging property of the developing roller at the same time.

Further, the invention of the image forming apparatus according to claim 5 is as follows.
The image forming apparatus includes the developing unit, the charging unit, the exposure unit, the transfer unit, the cleaning unit, and the electrophotographic photosensitive member as an image carrier.

According to the fifth aspect of the present invention, a high quality and high durability image forming apparatus can be obtained.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic apparatus as an image forming apparatus will be described below.

First, a schematic configuration of the electrophotographic apparatus according to the present embodiment will be described with reference to FIG.

An electrophotographic apparatus (image forming apparatus) 10 is disposed adjacent to the upper surface of a drum-shaped photoconductor (electrophotographic photoconductor) 12 and along a circumference thereof in a counterclockwise direction in a counterclockwise direction. 14. Charging charger (charging unit) 1
6, eraser 18, image exposure unit (exposure unit) 20,
Developing device (developing unit) 22, pre-transfer charger 2
4. Transfer charger (transfer unit) 26, separation charger 28, separation claw 30, charger 3 before cleaning
2. A fur brush 34 and a cleaning brush 36 are sequentially provided. Further, a registration roller 38 for feeding the transfer paper 38 between the photoconductor 12 and the transfer charger 26 and the separation charger 28 is provided.

In the electrophotographic method using the above-described electrophotographic apparatus 10, the photosensitive member 12 rotates counterclockwise,
The electrostatic latent image is charged negatively (or positively) by the charging charger 16, and the electrostatic latent image is
Form on top.

The photoreceptor 12 is composed of a drum-shaped conductive support and a photosensitive layer adhered to the upper surface thereof.

As the transfer means, generally, the above-mentioned charger can be used. However, as shown in FIG. 1, a combination of a transfer charger and a separation charger is effective.

The light sources used in the image exposure section 20, the static elimination lamp 14, and the like include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (LD). EL) or the like can be used. To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used. Such a light source or the like can be used even when a photoreceptor is irradiated with light by providing a transfer step, a cleaning step, or a pre-exposure step using light irradiation in combination.

In the developing device 22, the electrostatic latent image is developed by attaching toner onto the photoreceptor 12, and the charged state of the toner image is adjusted by the charger 24 before transfer. Transfer the toner image,
The electrostatic charger between the photoconductor 12 and the transfer paper 38 is eliminated by the separation charger 28, and the transfer paper 38 is separated from the photoconductor 12 by the separation claw 30. After the transfer paper 38 is separated,
The surface of the photoconductor 1 is cleaned by the pre-cleaning charger 32, the fur brush 34, and the cleaning brush 36 (cleaning unit). This cleaning can also be performed by removing the remaining toner with only the cleaning brush 36.

When the photosensitive member 12 is negatively (or positively) charged and subjected to image exposure, a negative (or positive) electrostatic latent image is formed on the photosensitive member 12. If this is developed with positively (or negatively) charged toner (electrostatic detection fine particles), a positive image can be obtained, and if it is developed with negatively (or positively) charged toner, a negative image can be obtained. A known method can be applied to such a developing unit, and a known method is also used for the charge removing unit.

In this example, the conductive support of the photoreceptor is shown as a drum, but a sheet or an endless belt can be used. As the pre-cleaning charger, known charging means such as a corotron, a scorotron, a solid state charger (solid state charger), a charging roller and the like can be used. The above-mentioned charging means can be usually used for the transfer charger and the separation charger, and a charger in which the transfer charger and the separation charger are integrated is efficient and preferable. Further, as the cleaning brush, a known brush such as a fur brush, a mag fur brush or the like can be used.

The internal structure of the developing device 22 will be further described with reference to FIG. FIG. 2 shows a state in which the apparatus shown in FIG. 1 is viewed from the back side of the paper.

The toner is sent to the developing roller 40 by an agitator (not shown). That is, it moves as indicated by the white arrow in FIG. 2 and moves to the toner pool formed at the press contact portion between the supply roller 42 and the developing roller 40. The supply roller 42 performs frictional charging of the toner by rotating while being in contact with the developing roller 40, and the charged toner is carried on the developing roller 40 and is transferred to the thin layer regulating member (supported thickness regulating member) 44. Moving. When the developing roller 40 rotates, the thin layer regulating member 44
, And the toner layer is transported to the developing area after being adjusted to an appropriate and uniform toner layer thickness (carrying thickness). Then, development is performed by transferring toner to the photosensitive drum 12 on which the latent image has been written by the exposure device (image exposure unit 20).

In FIG. 2, the photosensitive drum 12 and the developing roller 4
Although it is in a non-contact state with 0, it is also possible to develop by contacting both. In this case, the photosensitive member is formed in a belt shape instead of a drum, or an elastic member is used for a developing roller. It is common to secure a development area.

The surface of the supply roller 42 is desirably formed of a foamed elastic material. As the foamed elastic body, for example, foamed polyurethane having a cell diameter of 50 μm and Asker C hardness of 30 ° can be used. It is also possible to add carbon black or the like to make the conductive material.
By forming a bias electric field with 0, it is possible to control the toner supply property to the developing roller 40, the charging property, and the like.

Next, the developing roller 40 of the present invention will be described.

FIG. 3 shows a conductive support (an axis denoted by reference numeral 46 and a reference number 4) represented by a metal such as Al or SUS.
This is an example in which a surface layer 50 of the present invention is provided on a metal core indicated by reference numeral 8). FIG. 4 shows an example in which an elastic layer 50 is further provided on the cored bar 48, and the surface layer 50 of the present invention is provided on the elastic layer 50. The conductive support may have a hollow structure in order to reduce the weight.

The developing roller 40 can be provided with a special functional layer such as an oil-resistant layer or an adhesive layer between the respective layers as required.

The polyimide-modified silicone resin used on at least the surface of the developing roller 40 can be represented by the following general formula.

[0047]

Embedded image (In the formula, X is a tetravalent aromatic ring or an aliphatic ring group, R is a divalent organic group, and n is an integer of 5 or more.) Generally, polyimide is known as a high-strength and rigid resin. Introducing a siloxane structure into the main chain provides flexibility, and also has the advantage of improving the releasability. Therefore, by including the above-mentioned material at least on the surface, it becomes possible to satisfy the abrasion resistance of the developing roller and the toner releasability.

Such a polyimide-modified silicone resin can be produced using a mixture of siloxane diamine, aromatic diamine and tetracarboxylic dianhydride as a raw material.

As the siloxane diamine compound, H_TwoN-R₁-(-SiR_TwoR_Three-O-) n-SiR_FourR_Five-R₆-NH_Two  (R₁, R₆Is a divalent organic group, R_Two~ R_FiveIs an alkyl group, phenyl
Represents a group or a substituted phenyl group, and n is an integer of 5 to 50.
Is shown as a general formula, and specifically, bis (3-
Aminopropyl) tetramethyldisiloxane, bis (1
0-aminodecamethylene) tetramethyldisiloxane,
Dimethylsiloxane with aminopropyl end groups 4
, Octamer, bis (3-aminophenoxymethyl) tet
Lamethyldisiloxane and the like.

The aromatic diamine used in the present invention includes, for example, (1) biphenyl diamine compounds, diphenyl ether diamine compounds, benzophenone diamine compounds, diphenyl sulfone diamine compounds, diphenylmethane diamine compounds, 2,2-bis (phenyl) diamine compounds. ) Diphenylalkane diamine compounds such as propane, 2,2-bis (phenyl) hexafluoropropane diamine compounds, diphenylene sulfone diamine compounds, (2) di (phenoxy) benzene diamine compounds, di (phenyl) benzene Based diamine compound,
(3) di (phenoxyphenyl) hexafluoropropane diamine compound, bis (phenoxyphenyl)
Aromatic diamines mainly containing "aromatic diamine compounds having two or more aromatic rings (such as benzene rings), particularly 2 to 5 aromatic rings" such as propane-based diamine-based compounds can be used. Alternatively, they can be used as a mixture.

As the aromatic diamine, in particular,
Diphenyl ether diamine compounds such as 4-diaminodiphenyl ether and 1,3-diaminodiphenyl ether; di (phenoxy) benzene such as 1,3-di (4-aminophenoxy) benzene and 1,4-bis (4-aminophenoxy) benzene Based diamine compound, 2,
2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy)
[Phenyl] propane, etc., and bis (phenoxyphenyl) propane-based diamine-based compounds.

Next, specific examples of the tetracarboxylic dianhydride used in the present invention include pyromellitic dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride. Dianhydride, 3,3 ',
4,4′-benzophenonetetracarboxylic dianhydride,
3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3', 3,4'-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride 4,4'-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, ethylene glycol bistrimellitate dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl]
Propane dianhydride and the like, ', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3', 4,4'-
Biphenyltetracarboxylic dianhydride, 2,3 ', 3
4'-biphenyltetracarboxylic dianhydride and the like.

The polyimide-modified silicone resin used in the present invention can be produced by a known method using the compounds described above. For example, in an organic solvent, if necessary, by heating in the presence of a catalyst such as tributylamine, triethylamine, triphenyl phosphite or the like to directly obtain a polyimide, a tetracarboxylic dianhydride and a diamine are reacted in an organic solvent. After obtaining a polyamic acid which is a precursor of polyimide, a method of obtaining a polyimide by adding a dehydration catalyst such as p-toluenesulfonic acid as necessary and performing imidation by heating, or a method of obtaining the polyamic acid by acetic anhydride A method of adding an acid anhydride such as propionic anhydride or benzoic anhydride, a dehydrating ring-closing agent such as a carbodiimide compound such as dicyclohexylcarbodiimide and, if necessary, a ring-closing catalyst such as pyridine, isoquinoline, imidazole or triethylamine to chemically close the ring. There is.

The developing roller of the present invention only needs to comprise at least the surface of a polyimide-modified silicone resin.
If necessary, it can be used as a mixture with another organic or inorganic material. An example is specifically described. [Addition of Resistance Control Agent] By making the developing roller of the present invention conductive, it is possible to quickly eliminate the triboelectric charge remaining near the surface of the developing roller after development. FIG. 5 shows a case of a negatively charged toner as an example. In this case, the opposing charge generated by the frictional charging with the toner remains near the surface of the developing roller after the development of the toner. If this stays until the next development, it appears as a (negative) afterimage. In order to eliminate the residual charge, there is also a means of contacting the charge removing member with the surface of the developing roller to cause a leak, but there is a problem that it has a bad influence on abrasion of the thin toner layer and the surface layer.

According to the present invention, the volume resistance of the surface layer containing the polyimide-modified silicone resin of the developing roller is made to be 10 ¹² Ω · cm or less, so that the residual charges can be easily eliminated and the occurrence of an afterimage is prevented. When the volume resistance exceeds 10 ¹² Ω · cm, the residual charge cannot be quickly eliminated, and an afterimage occurs.

As the resistance controlling agent used for the developing roller of the present invention, a general resistance controlling agent can be used. Specific examples include materials such as carbon black such as Ketjen black and acetylene black, metal fine powder such as Ni powder, metal oxides such as titanium oxide and zinc oxide, quaternary ammonium bases, carboxylic acid groups, and sulfonic acid. Group, sulfate group,
Organic compounds or polymers containing a phosphate ester group or the like, ether ester amide or ether amide imide polymer, ethylene oxide-epihalohydrin copolymer, methoxypolyethylene glycol acrylate, etc. An organic antistatic agent such as an organic antistatic agent such as a compound can be used. [Addition of Charge Control Agent] The developing roller of the present invention can improve the charge characteristics of the toner by adding a charge control agent suitable for the charge polarity of the toner. For example, as the charge control agent used for the positively chargeable toner, a metal complex salt dye represented by an azo-chromium complex salt dye, a metal complex salt compound or a metal salt of a hydroxybenzoic acid derivative or an aromatic dicarboxylic acid, or an anthranilic acid derivative may be used. Compounds, organic boron compounds and biphenol compounds or oligomers.

The polyimide-modified silicone resin used in the present invention is located slightly negatively on the triboelectric series because it contains a siloxane component in the structure. Therefore, when a negatively chargeable toner is used, it is particularly effective to add a positively chargeable charge control agent to increase the toner chargeability. The positively chargeable charge control agent means that it is located on the positively chargeable side in the triboelectric series with respect to the polyimide-modified silicone resin, and the triboelectric series triboelectrically charges both, and the charge polarity of the cyclic polyolefin ( And the charging potential) can be easily known by measuring with a surface voltmeter.

For example, when the material used is a polymer,
A roller provided with a polyimide-modified silicone resin on the surface is installed in a developing device represented by FIG. 2, and is slid and rotated with a blade on which a material used on the surface is applied or adhered, so that the charging polarity (potential) of the roller is changed. It can be found by measuring. (At that time, other members are not in sliding contact with the developing roller such as the toner and the supply roller.) In the case of powder or liquid, the material is added to the cyclic polyolefin used for the developing roller, and the powder is placed on the blade surface. Similarly, it can be known by measuring the charging polarity of the roller. Examples of the charge control agent preferably used for the negatively chargeable toner include azine dyes represented by nigrosine, basic dyes represented by triphenylmethane dye, laked pigments of basic dyes, Metal complex dyes having a quaternary ammonium residue introduced into the mother skeleton;

Particularly preferred additives are maleimide resins containing quaternary ammonium bases and methacrylimide resins containing quaternary ammonium bases as shown in the following representative examples.

[0060]

Embedded image This is characterized by not only showing excellent positive charging property by containing quaternary ammonium but also being electrically conductive. Further, since it is an imide-based material similar to the polyimide-modified silicone resin used in the present invention, it has affinity and can be suitably used as an organic conductive agent. By using these materials, the conductivity can be controlled uniformly without variation in resistance.

The above materials are preferably added in an amount of 15 parts by mass or more based on 100 parts by mass of the polyimide-modified silicone resin. If the addition amount is less than 15 parts by mass, the resistance does not sufficiently decrease.

The layer containing at least the polyimide-modified silicone resin of the present invention can be used by mixing with various organic and inorganic materials as required in addition to the resistance control agent and the charge control agent.

Other organic resin materials that can be mixed include alkyd resin, chlorinated polyether, chlorinated polyethylene, epoxy resin, fluororesin, phenolic resin, polyamide, polycarbonate, polyethylene, methacrylic resin, polypropylene, and polystyrene. resin,
Polyurethane, polyvinyl chloride, polyvinylidene chloride,
Silicone resin and the like can be mentioned. These can be used by dissolving them in a solvent, or one of them can be mixed in the state of fine resin particles.

A general material for the elastic layer can be used.

Specifically, polyurethane, butyl rubber,
Use of nitrile rubber, epichlorohydrin rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, fluoro rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, chloroprene rubber, acrylic rubber, and mixtures thereof Can be done. These rubber materials are usually insulative except for a part, but when applying a bias voltage as described above, it is also possible to add the above-mentioned resistance control agent and make it conductive.

Next, a method for manufacturing the developing roller of the present invention will be described. [Method of Forming Conductive Layer] In forming the developing roller of the present invention, a press forming method of simultaneously heating and pressing a conductive support and a rubber composition for forming an elastic layer in a mold, a conductive support and a rubber After extruding the composition integrally using a crosshead with an extruder, an extrusion molding method of primary vulcanization in a gear oven or an infrared furnace, a conductive support is set in a molding die, and then the An injection molding method in which the above composition is injected and heated is used, and the surface can be polished if necessary. [Method of dissolving a polyimide-modified silicone resin in a solvent and coating and molding] When a polyimide-modified silicone resin is dissolved in a solvent to form a developing roller, it can be carried out according to a conventional method. Can be carried out by casting a liquid composition dissolved or dispersed in an appropriate carrier (support), and then drying and removing the solvent.

The carrier is not particularly limited and those used in a general solution casting method are used. Examples thereof include a metal roller such as SUS and Al, a conductive resin roller, and a rubber roller. it can.

As the solvent, for example, N-methyl-2-
Pyrrolidone, N, N-dimethylacetamide, N, N-
Dimethylformamide, dimethylsulfoxide, sulfolane, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidone, hexane, benzene, toluene, xylene, methylethylketone, acetone, diethylether, tetrahydrofuran, dioxane, 1,2
-Dimethoxymethane, diethylene glycol dimethyl ether, methyl cellosolve, cellosolve acetate, methanol, ethanol, propanol, isopropanol, methyl acetate, ethyl acetate, acetonitrile, methylene chloride, chloroform, carbon tetrachloride, chlorobenzene,
Examples thereof include dichlorobenzene, dichloroethane, and trichloroethane, and the type and amount thereof are appropriately selected and used so that each component is dissolved and dispersed.

The concentration of the polyimide-modified silicone resin in the solvent is appropriately selected according to the film thickness to be produced, but is usually 0.1 to 60% by mass, preferably 1 to 50% by mass, more preferably 5 to 45% by mass. % By mass. When the concentration of the cyclic olefin-based polymer is within this range, the film thickness can be easily adjusted and the film-forming property is excellent, which is preferable.

The method of casting the liquid composition on the carrier is not particularly limited, but it can be carried out using, for example, a doctor knife, Meyer bar, roll coat, or the like. The liquid composition can be cast by spraying, brushing, rolling, spin coating, dipping, or the like. If the desired film thickness cannot be obtained by one coating, the coating can be repeated.

[0071]

The present invention will be further described with reference to Examples and Comparative Examples. The present invention is not limited to the embodiments described below. [Example 1] <Developing roller surface layer forming component> Polyimide-modified silicone resin (X-22-8917; Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Cyclohexanone 100 parts by mass Methyl ethyl ketone 100 parts by mass A SUS plate (0.1 mm thick) ), And left in a thermostat at 200 ° C. for 1 hour to prepare a sample plate (film thickness: 20 μm). <Evaluation of thin layer regulating member> Toner releasability test A sample plate was brought into contact with a toner (Ricosian toner type 4100) as shown in FIG. 9 and was subjected to 980 kPa, 50 ° C., 1 hr using a simple press machine for a laboratory. Heating and pressurizing were performed under the following conditions. After the test, the toner was blown off with air at 294 kPa, and the toner residual state was visually evaluated as follows.

Releasability Rank Rank 8 Very Easy Removal of Toner 7 Takes Some Time but Completely Removes Toner 6 Slight (Several% or Less) Toner Remains 5 Some% to ３ 4 Residual toner of about 1/3 to 2/3 3 Residual toner of 2/3 or more 2 Residual toner on entire surface (present as toner particles) 1 Residual toner on entire surface (Toner The particles are not present as particles, but are fused together.) Spin-off test The same component for forming the surface layer of the developing roller is spray-coated on a 16 mmφ Al core, left in a constant temperature bath at 200 ° C. for 1 hour, taken out, and gradually cooled. The surface was polished to form a developing roller. This was mounted on the developing device shown in FIG. 2, and a running test for 100 hours was performed. The following members were used for each member of the developing device.

Toner Ricosian Toner Type 4100 Thin blade SUS 100 μm thick Supply roller Conductive urethane sponge Linear speed Developing roller = 100 mm / sec, Supply roller = 120 mm / sec Potential Developing roller = ground, Supply roller = −150 V, Thin layer Restriction member = float During the idle rotation, a thin layer state of the toner was observed. After idling, the toner on the developing roller is blown by air, and the residual toner on the surface is transferred to a tape. This is affixed to blank paper, and the image density is measured (measurement device: X-Rite 938 Spee).
trodensitometer). The density of the blank was also measured, and the difference was used as the index value ΔI of the filming toner amount.
D (filming).

Next, the diameter of the developing roller was measured with a laser microcage (LS3100; manufactured by KEYENCE CORPORATION), and the wear amount (μm) was calculated from the difference between before and after idling. Example 2 Samples and rollers were prepared in the same manner except that the polyimide-modified silicone resin (X-22-8917) used in Example 1 was changed to a polyimide-modified silicone resin (X-22-8904; Shin-Etsu Chemical). The same evaluation was performed. [Example 3] <Synthesis of polyimide-modified silicone resin> 791 g of dehydrated and purified N-methyl-2-pyrrolidone (NMP) was placed in a four-necked flask equipped with a dry nitrogen gas inlet tube, a cooler, a thermometer, and a stirrer. And while flowing nitrogen gas, 10
After stirring vigorously for 2 minutes, 2,2-bis (4- (4-aminophenoxy) phenyl) propane (BAPP) 0.1
0 mol, diaminopolydimethylsiloxane (X-22
-161AS; Shin-Etsu Chemical Co., Ltd.) was added, and the system was heated to 60 ° C and stirred until uniform. Next, the system was cooled to 5 ° C. or lower in an ice water bath, and trimellitic anhydride 0.4 was added.
2 mol was added and stirring was continued for 3 hours thereafter. During this time, the flask was kept at 5 ° C. or lower. Thereafter, the nitrogen gas inlet tube and the condenser were removed, a Dean-Stark tube filled with xylene was attached to the flask, and 198 g of xylene was added to the system. The system was heated to about 175 ° C. in place of an oil bath, and generated water was removed from the system. After heating for 4 hours, generation of water from the system was no longer observed, the system was cooled, and the reaction solution was poured into a large amount of methanol to precipitate a resin. After the solid content was filtered, the residue was dried under reduced pressure at 80 ° C. for 12 hours to remove the solvent, thereby obtaining a silicone-modified polyimide resin A.

A sample and a roller were prepared from the obtained resin in the same manner as in Example 1, and the same evaluation was performed. Comparative Example 1 <Developing Roller Surface Layer Forming Component> Polyimide resin (UPILEX S: Ube Industries, Ltd.) 100 parts by mass N-methyl-2-pyrrolidone 500 parts by mass A sample and a roller were prepared using the above materials in the same manner as in Example 1. The same evaluation was performed. Comparative Example 2 <Developing Roller Surface Layer Forming Component> Silicone resin (SR2411; Toray silicone) 100 parts by mass Toluene 100 parts by mass A sample and a roller were prepared from the above materials in the same manner as in Example 1, and the same evaluation was performed. . Comparative Example 3 <Developing Roller Surface Layer Forming Component> Epoxy-Modified Silicone Resin (SR2115; Toray Silicone) 100 parts by mass Aminosilane Coupling Agent (SH6020; Toray Silicone) 5 parts by mass Toluene 100 parts by mass Similarly, a sample and a roller were prepared, and the same evaluation was performed.

Table 1 shows the results.

[0077]

[Table 1] Example 4 <Developing Roller Surface Layer Forming Component> Polyimide-modified silicone resin (X-22-8904; Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Cyclohexanone 100 parts by mass Methyl ethyl ketone 100 parts by mass Carbon black (Black Pearl L; Degussa) 0 , 15, 22, 30, 45 parts by mass The above carbon black was added to the surface layer forming component used in Example 2, and the mixture was dispersed in a ball mill for 72 hours. This was spray-coated to obtain a developing roller in the same manner as in Example 2. The thickness of the surface layer is 15 μm.

The volume resistance of the developing roller is set to DC 100 V
Was calculated from the resistance value after 1 minute using the following equation.

Volume resistance R (Ω · cm) = (measured resistance R
') × ln {(2πL) / (a / b)} L: main electrode width, a: developing roller diameter, b: core metal diameter The results of the carbon black addition amount and the volume resistance are shown in FIG.

Next, this was mounted on the same developing device as in Example 1, and the image lag was measured using an image forming apparatus using a belt photoreceptor.

Evaluation of image persistence A pattern image as shown in FIG. 7 was output to evaluate the image persistence. That is, after developing the solid black band in FIG. 7 (shown by a satin finish in FIG. 7), the halftone dots are developed, and the image density ( _IDl ) of the halftone dot corresponding to the position of the solid black band and the portion other than the black solid band equivalent portion The image density (ID _h ) of the halftone dot was measured with a Macbeth densitometer, and the afterimage was evaluated based on the ratio (ID ₁ / ID _h ). In other words, if the ratio is 1, no afterimage is generated and the image quality is good, but as the ratio deviates from 1, the degree of the afterimage becomes worse.
The allowable range of the persistence is 1 ± 0.1.

FIG. 8 shows the results of the resistance and the degree of persistence. [Example 5] <Elastic layer forming component> Silicone rubber (SH831U; Toray silicone) 100 parts by mass Carbon black / thermal black (manufactured by Asahi Carbon Co.) 12 parts by mass Vulcanizing agent (C8; Shin-Etsu Chemical) 2 parts by mass Is kneaded with two rolls, and together with an 8φ SUS core metal to which an adhesive primer has been applied beforehand, at 175 ° C and 10 ° C in a molding die.
The mixture was vulcanized and adhesively molded with the core metal for minutes. Thereafter, secondary vulcanization was performed in an oven at 200 ° C. for 4 hours, followed by polishing with a cylindrical grinder to obtain a conductive elastic layer having a layer thickness of 4 mm. (Electrical resistance about 10
⁵ Ω) The developing roller surface layer forming component (carbon black content: 30 parts by mass) used in Example 4 was spray-coated on the elastic layer, and a developing roller was obtained in the same manner. The thickness of the surface layer is 10 μm. This was mounted on the image forming apparatus using the drum photoreceptor shown in FIG. 1, and a paper passing test of 100,000 sheets was performed. Table 2 shows the results of measurement of the afterimage before and after the test, the ΔID releasability after the test, the amount of abrasion, and the crack (observation with a microscope).

[0083]

[Table 2] Example 6 <Components for Forming Developing Roller Surface Layer> Polyimide-modified silicone resin (X-22-8904; Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Cyclohexanone 100 parts by mass Methyl ethyl ketone 100 parts by mass Maleimide resin containing quaternary ammonium base (Leolex AS170) ; Daiichi Kogyo Seiyaku) 0, 5, 10, 15, 25, 45 parts by mass The surface layer forming component is formed on the elastic layer in the same manner as in Example 5, and the volume resistance and ΔID (ground contamination), the toner charge amount, The amount of adhesion and the afterimage were measured. The results are shown in Table 3.

[0084]

[Table 3] ΔID (ground stain); measuring device; X-Rite 938
Stain density measured with Spectrodensitometer Toner charge amount, adhesion amount; suction method

According to the present invention, there is provided a developing unit (developing device) having a developing roller excellent in toner releasing property and abrasion resistance by containing at least a polyimide-modified silicone resin on the surface.

Further, the image forming apparatus using the developing device of the present invention can provide a high-quality image without an afterimage for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an electrophotographic apparatus according to an embodiment.

FIG. 2 is a schematic diagram of a developing device according to the exemplary embodiment.

FIG. 3 is a schematic view of an example of a developing roller according to the exemplary embodiment.

FIG. 4 is a schematic view of another example of the developing roller according to the exemplary embodiment.

FIG. 5 is a diagram for explaining the behavior of the toner.

FIG. 6 is a graph showing the relationship between the added amount of carbon black and the volume resistance.

FIG. 7 is a diagram showing a pattern image output to evaluate the afterimage.

FIG. 8 is a graph showing the relationship between resistance and the degree of afterimage.

FIG. 9 is a view showing a test plate in contact with a toner used in a toner release property test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electrophotographic apparatus 12 Photoreceptor 14 Static elimination lamp 16 Charging charger 20 Image exposure part 22 Developing device 26 Transfer charger 34 Fur brush 36 Cleaning brush 40 Developing roller 42 Supply roller 44 Thin layer regulating member 46 Shaft 48 Core metal 50 Surface layer 52 Rubber layer

Claims (5)

[Claims] A developing roller that moves while carrying the toner on the surface and conveys the toner onto the image carrier; and a developing roller that contacts the developing roller via the toner carried on the developing roller. And a carrying thickness regulating member that regulates the carrying thickness of the developing roller. A developing unit characterized in that at least the surface is made of a material containing a polyimide-modified silicone resin. 2. The developing roller comprises a plurality of layers, at least a surface layer made of a material containing the polyimide-modified silicone resin, and a layer other than the surface layer having an elastic layer. The developing unit according to claim 1. 3. The volume resistance of a portion composed of a material containing the polyimide-modified silicone resin is 10 ¹² Ω · cm.
3. The developing unit according to claim 1, wherein: 4. The method according to claim 1, wherein the portion composed of the material containing the polyimide-modified silicone resin is either one or both of a quaternary ammonium salt-containing maleimide resin and a quaternary ammonium salt-containing methacrylimide resin, and 100 parts by mass of the polyimide-modified silicone resin. The developing unit according to claim 1, wherein the developing unit is contained in an amount of 15 parts by mass or more per part. 5. An electrophotographic photosensitive member as a developing unit, a charging unit, an exposure unit, a transfer unit, a cleaning unit, and an image carrier according to claim 1. Image forming apparatus.