JP2780168B2 - Electrostatic latent image carrier and image forming method and apparatus using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image carrier used for an electrophotographic apparatus such as a copying machine, a printer and a facsimile, and a method and an apparatus for forming an image using the same. This enables formation of a high-quality image.

[0002]

2. Description of the Related Art In recent years, electrophotographic apparatuses have attracted attention because of their advantages such as high speed, low noise, high image quality, and the ability to record on plain paper. It is also spreading rapidly. In addition, as a recent trend, particularly in the field of printers and facsimile machines, the mode of use has been shifting from office use to personal use.
There is also a demand for a technique for realizing smaller size, lower cost, maintenance free, and the like for the electrophotographic apparatus.

In general, electrophotographic image formation is performed in the following order. First, an electrophotographic photosensitive member, which is an electrostatic latent image holding member, is uniformly charged, and then an image signal is written on the photosensitive member by exposure means to form an electrostatic latent image. continue,
In the developing step, the electrostatic latent image formed on the photoreceptor is visualized with toner, which is a colored powder, and the toner is transferred and fixed on copy paper to form a copy image. on the other hand,
After the residual toner after the transfer is removed by the cleaning process, the photosensitive member is charged if necessary, and is repeatedly used in the image forming process again.

As described above, the electrophotographic process is constituted by at least the steps of charging, exposing, developing, transferring and cleaning. The electrostatic latent image holder used in this process must have excellent electrostatic characteristics and be a photosensitive member suitable for an electrophotographic process and an electrophotographic apparatus in which it is used.

In recent years, an organic photoconductor containing an organic photoconductive material has been developed and put to practical use, which has advantages such as easy film formation, low cost and no pollution. I have. Particularly, in a laser beam printer or a facsimile using a semiconductor laser as an exposure light source, the characteristic of having high sensitivity in a long wavelength region of an organic photoreceptor is adapted, so that the use thereof is remarkably expanding. Most of the organic photoreceptors that have been put into practical use are stacked organic photoreceptors in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated, and the structure of function separation greatly increases The characteristics are improved.

In the electrophotographic image forming method, a cascade developing method, a touch-down developing method, a jumping developing method and the like are known as developing methods for visualizing an electrostatic latent image. Among them, the cascade development method is a development method used in a first practical copying machine for electrophotography, in which a developer is directly sprayed on a photoreceptor.
No. 5770. The touch-down development method is a method in which an AC bias is applied to a development roller to cause one-component toner to fly and develop the image.
No. 74. In this developing method, it is described that the AC bias applied to the developing roller is used for activating the movement of the toner, and the toner flies to the image portion and returns to the middle in the non-image portion.

Further, as an improvement of the technique of applying the AC bias, there is a jumping development disclosed in Japanese Patent Publication No. 63-42256. In this jumping development method, toner is carried on a toner carrier, and a rigid or elastic regulating blade is provided on the toner carrier with a small gap from the carrier. Then, the toner is regulated to a thin layer by the regulating blade and transported to the developing section, where the toner is attached to the image area of the photoconductor by an AC bias. The technical idea of Japanese Patent Publication No. 63-25656 is different from the above-mentioned U.S. Pat. No. 3,866,574 in that the toner reciprocates in the image portion and the non-image portion.

However, each of these developing methods has a disadvantage. In the cascade developing method, solid image reproducibility is poor, and the apparatus becomes large and complicated. Further, the developing method described in U.S. Pat. No. 3,866,574 has disadvantages in that high precision is required for the apparatus, the configuration thereof is complicated, and the cost is high. Further, in the jumping development method, it is necessary to form an extremely uniform thin toner layer on a toner carrier, but this is difficult. The developing characteristics of this developing method depend on the thickness of the toner layer. If the layer thickness is not uniform, the history of the previous image remains in the thin toner layer on the toner carrier, and So-called sleeve ghost development occurs in which an afterimage appears. It also has the disadvantage that the device is complicated and the cost is high.

Accordingly, we have proposed an electrophotographic method and an apparatus capable of realizing high-performance development at a low cost with a small apparatus (for example, Japanese Patent Application No. 3-34).
No. 5990 (JP-A-5-72890).

As shown in FIG. 1, the apparatus comprises a photosensitive drum 1 as an electrostatic latent image holding member, a magnet 2 fixed coaxially with the photosensitive member 1, and a corona charger for charging the photosensitive member 1. 3
A grid electrode 4 for controlling the charging potential of the photoconductor 1,
A toner reservoir 6 for storing a magnetic toner 7, an electrode roller 9 having a magnet 10 coaxially fixed therein, and a smooth flow of the toner in the toner reservoir 6. The toner is crushed by its own weight and exposed to light. A damper 8 for preventing clogging between the body 1 and the electrode roller 9; an AC high-voltage power supply 11 for applying a voltage to the electrode roller 9; a scraper 12 for scraping toner on the electrode roller 9; And a transfer corona charger 13 for transferring the upper toner image onto the image receiving paper 14. Note that reference numeral 5 in FIG. 1 represents signal light for exposure.

At the time of development, the photoreceptor 1 of this apparatus is rotated in the direction of the arrow, the surface of the photoreceptor is charged to -500 V using a corona charger 3, and then irradiated with a laser beam 5. An electrostatic latent image corresponding to the image signal is formed on the surface of the photoconductor. The photoconductor 1 rotates in contact with the magnetic toner 7 in the toner reservoir 6, and in this process, the magnetic toner 7 adheres to the surface of the photoconductor 1 by the magnetic force of the fixed magnet 2. The magnetic toner carried on the photoreceptor 1 then passes in front of the electrode roller 9 rotating in the direction of the arrow.

The electrode roller 9 is applied with an AC voltage of 750 V _0-p (frequency 1 kHz) on which a DC voltage of -350 V is superimposed from an AC high voltage power supply 11. Therefore, the magnetic toner carried on the photoconductor 1 is collected toward the electrode roller 9, and a negative-positive toner image is left only on the image portion on the photoconductor 1. The toner adhered to the electrode roller 9 is scraped off by the scraper 12 by the rotation of the electrode roller 9, returned to the toner reservoir 6 again, and used for the next image formation.

The toner image formed on the photoreceptor 1 is transferred to an image receiving paper 14 by a transfer corona charger 13 and then fixed to form a print image.

As described above, in this apparatus, the photoreceptor containing the fixed magnet, the toner reservoir disposed to face the surface of the photoreceptor, and the fixed magnet built-in opposed to the photoreceptor with a predetermined gap therebetween are provided. Using an electrode roller, the magnetic toner supplied from the toner reservoir is attracted by the magnetic force of the fixed magnet to be carried on the surface of the photoconductor, and then the unnecessary toner in the non-image area on the photoconductor is collected by the electrode roller. Developing.

According to this developing method, a solid image can be faithfully reproduced, no sleeve ghost is generated, and the apparatus can be reduced in size, simplified, and reduced in cost.

[0016]

In this developing system, the structure of the apparatus such as the magnetic flux density of the fixed magnets inside the photoconductor and the electrode roller, the magnetic pole angles of the two fixed magnets facing each other, or the gap between the photoconductor and the electrode roller. The above conditions, or the setting conditions in development, such as the charging potential of the photoreceptor and the voltage applied to the electrode roller, and the physical properties of the magnetic toner, such as the fluidity of the magnetic toner, the amount of charge, or the particle size, are formed. It has a significant effect on the image quality. Therefore, the image quality is optimized by adjusting and selecting these conditions and physical properties. However, it has also been found that the surface properties of the photoreceptor greatly affect the solid image density and the occurrence of toner adhesion (so-called background fogging) in non-image areas.

The present invention has been made in view of such a viewpoint. In the above-described image forming method, the image forming method has a high image density and has a surface property capable of obtaining high image quality with little fogging. Provided is an electrostatic latent image holder, and an image forming method and an image forming method capable of realizing higher image quality, miniaturization, simplification, and cost reduction of an apparatus by using the electrostatic latent image holder. It is intended to provide a device.

[0018]

Therefore, in the present invention, the electrostatic latent image holding member on which the electrostatic latent image has been written carries the magnetic toner magnetically attached to the collection unit, and the electrostatic force and the magnetic force are reduced. The contact angle of pure electrostatic water on the surface of the electrostatic latent image holder used in the developing method for recovering the magnetic toner attached to the non-image portion of the electrostatic latent image holder with the given electrode roller from 70 ° to 1 °.
It is set in the range of 10 °.

Further, the electrostatic latent image holding member is formed by a cylindrical conductive support, a charge generation layer containing a charge generation material laminated thereon, and a charge transport layer containing a charge transport material. Make up.

Further, at least a part of the electrostatic latent image holding member is formed of an organic photoreceptor.

The charge generation layer of the electrostatic latent image carrier contains at least a phthalocyanine pigment.

Further, the charge transport layer of the electrostatic latent image holding member is constituted by an organic resin layer containing a charge transport substance and a binder resin.

Further, in an image forming method for forming an electrostatic latent image on an electrostatic latent image holding member and forming the electrostatic latent image with a magnetic toner, the electrostatic latent image holding member may be provided with pure water on its surface. A magnetic toner is magnetically attached to an electrostatic latent image holding member on which an electrostatic latent image is written by using a member having a contact angle of 70 ° to 110 ° with respect to the electrostatic latent image. By moving the body, the magnetic toner is conveyed to the collection unit, and the magnetic toner attached to the non-image portion of the electrostatic latent image holding member is collected by an electrode roller that applies electrostatic force and magnetic force.

Further, as the electrostatic latent image holding member, a cylindrical conductive support, a charge generation layer containing a charge generation material laminated thereon, and a charge transport layer containing a charge transport material are provided. The provided electrostatic latent image holder is used.

Further, as the electrostatic latent image holding member, an electrostatic latent image holding member containing at least an organic photosensitive member as a part thereof is used.

Further, as the electrostatic latent image holder, an electrostatic latent image holder containing at least a phthalocyanine pigment is used for the charge generation layer.

Further, as this electrostatic latent image holder, an electrostatic latent image holder whose charge transport layer is made of an organic resin layer containing a charge transport material and a binder resin is used.

Further, in an image forming apparatus including an electrostatic latent image holding member that holds and moves an electrostatic latent image and a unit that images the electrostatic latent image with magnetic toner, the electrostatic latent image holding member The contact angle of pure water on pure water from 70 ° to 110 °
, A fixed magnet that applies a magnetic field to the surface of the electrostatic latent image holder, a toner reservoir having an opening facing the surface of the electrostatic latent image holder, and a surface of the electrostatic latent image holder. An electrode roller rotating at a position facing the electrode roller, a magnet included in the electrode roller, and voltage applying means for applying an electrostatic force to the electrode roller, and an electrostatic latent image holder on which an electrostatic latent image is written Magnetic toner is magnetically attached to the surface of the electrostatic latent image holding member, and the magnetic toner attached to the non-image portion of the electrostatic latent image holding member is collected by the electrode roller applied with electrostatic force and magnetic force. ing.

Further, as the electrostatic latent image holding member, an electrostatic latent image holding member having the above-mentioned respective constituent elements is used.

[0030]

The magnetic toner is magnetically adhered to the electrostatic latent image holding member on which the electrostatic latent image is written, and the magnetic toner is carried to the collection unit by moving the electrostatic latent image holding member, and the static toner is moved. When a method of recovering and developing the magnetic toner attached to the non-image portion of the electrostatic latent image holding member by using an electrode roller that provides electric power and magnetic force is employed, the magnetically attached toner and the electrostatic latent image holding member The frictional force or the slipperiness varies depending on the surface properties of the electrostatic latent image holding member. If the surface properties are different, the amount of toner carried and transported to the electrode roller portion or the amount of charged toner generated by frictional charging will be different. If these amounts are not appropriate, the solid image density will be reduced, or the background will be fogged in the non-image area, and the image quality will be reduced. In other words, when toner larger than the toner collecting capacity of the electrode roller is carried and transported by the electrostatic latent image holding member, ground fogging occurs. On the contrary, when the amount of toner carried and transported is small, the solid image density is reduced. Is thought to decrease.

In the present invention, by setting the contact angle of the surface of the electrostatic latent image holding member to pure water in the range of 70 ° to 110 °, the amount of toner carried and conveyed by the electrostatic latent image holding member is optimized. Is becoming As a result, even under various developing conditions of the above-described image forming method, it is possible to obtain a high-quality image having a high image density and little background fog.

The electrostatic latent image holding member was constituted by a cylindrical conductive support, a charge generation layer containing a charge generation material laminated thereon, and a charge transport layer containing a charge transport material. It has good and stable electrophotographic properties.

When the photosensitive portion of the electrostatic latent image holding member is made of an organic photosensitive member, it is easy to form a film, does not require cost, and is manufactured without using a substance that causes pollution. be able to.

Further, as a charge generating substance of the organic photoreceptor,
When a phthalocyanine pigment is used, an electrostatic latent image holder having high sensitivity in a long wavelength region of a semiconductor laser beam can be obtained.

[0035]

In the present invention, the contact angle of the surface with pure water is 7
As long as the electrostatic latent image holding member is in the range of 0 ° to 110 °, any structure of the electrophotographic photosensitive member can be used, but in the examples, the electrophotographic characteristics are good and stable. Therefore, on a cylindrical conductive support, as a photoreceptor, a stack type electrophotograph in which an organic charge generation layer containing a charge generation substance and a charge transport layer of an organic substance containing a charge transport substance are sequentially laminated. The photoconductor will be described.

The charge generating substance to be added to the charge generating layer includes phthalocyanine, azo, squarylium,
Organic pigments such as perylene and cyanine can be used.
In particular, many phthalocyanine pigments have sensitivity up to long wavelengths in the near infrared region, and are suitable for laser beam printers and laser facsimile machines using a semiconductor laser as an exposure light source. Examples of the phthalocyanine pigment include metal-free phthalocyanines and various metal phthalocyanines, specifically, α-type copper phthalocyanine, β-type copper phthalocyanine, ε-type copper phthalocyanine, τ-type metal-free phthalocyanine, X-type metal-free phthalocyanine, α-type titanyl phthalocyanine. And β-type titanyl phthalocyanine.

The charge generating layer is formed by dispersing the charge generating substance and a suitable binder resin in a solvent, applying the prepared coating solution by a usual coating method, and drying. At this time, the film thickness after drying is 1 μm in terms of electrophotographic characteristics such as sensitivity and repetition stability.
Hereafter, it is desirable to form it to preferably about 0.5 μm or less.

Examples of the charge transporting substance to be added to the charge transporting layer include compounds having an electron donating group such as an alkyl group, an alkoxy group, an amino group, and an imide group;
Polycyclic aromatic compounds such as pyrene and phenanthrene or derivatives containing them, heterocyclic compounds such as oxazole, carbazole, pyrazoline and indole or derivatives containing them, hydrazone compounds and stilbene compounds can be used. The charge transport layer dissolves at least these charge transport substances and a binder resin in a suitable solvent,
It is formed by coating and drying by a normal coating method. The thickness of the charge transport layer after drying is preferably several μm to several tens μm, and more preferably 5 to 25 μm.

The binder resin used for forming the charge generation layer and the charge transport layer is added for the purpose of improving the adhesion to other layers, improving the uniformity of the coating film, and adjusting the fluidity during coating. Specifically, known thermoplastic resins or thermosetting resins such as polyvinyl chloride resin, polyvinyl butyral resin, polyvinyl acetate resin, polycarbonate resin, polyarylate resin, polyester resin, acrylic resin, and silicone resin can be used. As the solvent, any type of solvent can be used as long as it can dissolve the charge transporting substance or the binder resin. Usually, ketones such as methyl ethyl ketone, ethers such as tetrahydrofuran, methylene chloride, carbon tetrachloride, and the like can be used. And halogenated hydrocarbons such as benzene, and aromatic hydrocarbons such as toluene.

As the conductive support of the electrostatic latent image holding member, a conventionally known conductive plate or drum can be used. For example, a metal plate such as aluminum or aluminum alloy can be used. Or metal drum, tin oxide,
A plate or a drum of a metal oxide such as indium oxide, or a material obtained by attaching the metal or the metal oxide to various plastic films or drums by vapor deposition, sputtering, laminating, coating, or the like can be used.

In addition, between the conductive support and the photosensitive layer,
An adhesive layer, a barrier layer, or a conductive layer may be provided as in the case of a normal electrophotographic photosensitive member.

The contact angle of the surface of the laminated electrophotographic photosensitive member with respect to pure water depends on the material composition and surface roughness of the charge transporting layer as the surface layer, drying conditions at the time of coating, and the like. This contact angle can be regarded as a numerical value representing the lubricity of the surface. When the contact angle is small, the lubricity is poor, and when the contact angle is large, the lubricity is good. The contact angle is measured at a temperature of 22 ° C. using an automatic contact angle meter manufactured by Kyowa Interface Science Co., Ltd. The measurement of the contact angle by this instrument is to calculate the contact angle from the droplet shape of pure water. As shown in FIG. 2, when the height of the droplet is h and the radius of the droplet is r, The angle (the angle with the tangent of the droplet) θ is θ = 2 tan ⁻¹ (h /
r).

The contact angle with respect to pure water on the surface of the electrostatic latent image holding member is set in the range of 70 ° to 110 °. If the contact angle is 110 ° or more, a sufficient solid image density cannot be obtained, and if the contact angle is 70 ° or less, the background fog increases. This is because when the contact angle of the surface is 110 ° or more, the frictional force between the toner adhered to the surface of the electrostatic latent image holding member and the electrostatic latent image holding member is small, and the lubricating property is too good. It is considered that the amount of toner adhered to the image carrier and conveyed is reduced, and as a result, the solid image density is reduced. On the other hand, when the contact angle of the surface is 70 ° or less, the amount of the toner adhered to the electrostatic latent image holding member increases, and the amount exceeds the toner collecting ability at the electrode roller. Conceivable.

For image formation, the aforementioned Japanese Patent Application No. 3-345
No. 990, the electrostatic latent image is formed on an electrostatic latent image holding member containing a fixed magnet, and then the magnetic toner is brought into contact with the electrostatic latent image to magnetically adhere the magnetic toner. In this state, the magnetic toner is carried and transported to the electrode roller section.
On the other hand, an AC bias is applied to the electrode roller to remove the magnetic toner attached to the non-image portion on the electrostatic latent image holding member by electrostatic force and magnetic force, and develop the toner.

The magnetic toner used for image formation contains at least a binder resin and a magnetic material as components, and if necessary, a colorant, a charge control agent, a release agent, a fluidizing agent, a second external additive Is added. As the binder resin, a styrene acrylic resin, a polyester resin, or the like can be used, and if necessary, other known polymers or copolymers can be used. Further, as the magnetic material to be blended, metal powders such as iron, manganese, nickel, and cobalt, and ferrites such as iron, manganese, nickel, cobalt, and zinc can be used. The addition amount of the magnetic material is 20 to
60% by weight is preferable, and when the addition amount is 20% by weight or less, the toner scattering tends to increase.

Examples of the coloring agent and charge controlling agent include carbon black, iron black, graphite, nigrosine, metal complexes of azo dyes, phthalocyanine blue, celco oil blue, Dupont oil red, aniline blue, benzidine yellow, rose bengal and the like. Pigments or dyes such as mixtures thereof can be used.

The release agent is polyethylene or polypropylene, and the external additives are hydrophobic silica, titania,
Inorganic fine powders such as alumina and zirconia, and tin oxide, strontium titanate, barium titanate, and tungsten carbide can be used as abrasives and fluidity aids. Fine powders of organic materials and other types of additives may be incorporated for the purpose.

Next, specific examples of the electrostatic latent image holding member, the image forming method and the apparatus for implementing the same will be described in detail.

Example 1 Two parts by weight of a τ-type metal-free phthalocyanine (manufactured by Toyo Ink Manufacturing Co., Ltd.) and 2 parts by weight of a polyvinyl butyral resin (trade name: SLEX BL-1 manufactured by Sekisui Chemical Co., Ltd.) were used. In addition to 96 parts by weight of butanol, the mixture was dispersed in a ball mill for 4 hours. This dispersion was applied onto an aluminum drum having an outer diameter of 30 mm by dip coating, and air-dried to form a charge generation layer having a thickness of about 0.2 μm.

Next, 1,1-bis (p-diethylaminophenyl) -4,4-diphenyl-1,3 butadiene 1
1 part by weight of a polycarbonate resin (trade name: Iupilon Z-300, manufactured by Mitsubishi Gas Chemical Industry Co., Ltd.) was dissolved in 9 parts by weight of methylene chloride, and a paint was applied on the charge generating layer by dip coating. Drying for 2 hours, film thickness about 20μm
Was formed to obtain a laminated electrophotographic photosensitive member.

Pure water is dropped on the surface of the electrophotographic photosensitive member manufactured as described above, and the contact angle of the pure water at a temperature of 22 ° C. is measured using an automatic contact angle meter CA-Z manufactured by Kyowa Interface Science Co., Ltd. did. As a result, the contact angle was 85 °.

Using this electrophotographic photosensitive member as the electrostatic latent image holder 1 of the image forming apparatus shown in FIG. 1, an image was formed.

As the magnetic toner, a negatively chargeable magnetic one-component toner having an average particle diameter of about 7 μm using a styrene acrylic resin as a binder was used. The composition of this magnetic one-component toner is 70 parts by weight of styrene acrylic resin, 25 parts of ferrite.
Parts by weight, 3 parts by weight of carbon black, and 2 parts by weight of a metal complex of oxycarboxylic acid.
0.4 parts by weight of colloidal silica is externally added.

The magnetic flux density on the surface of the photoreceptor 1 by the magnet 2 is 600 Gs, and the magnetic pole angle of both the magnet 2 and the magnet 10 is 15
Set to degree. The photoconductor 1 is rotated at a peripheral speed of 65 mm / s in the direction of the arrow in the figure, the electrode roller 9 is set to a diameter of 16 mm, and at a peripheral speed of 40 mm / s, the direction opposite to the traveling direction of the photoconductor. (In the direction of the arrow in the figure). The gap between the photoconductor 1 and the electrode roller 8 is 300 μm.
Set to.

At the time of image formation, the photoreceptor 1 of this image forming apparatus is charged to -500 V by a corona charger 3 (applied voltage of -5.3 kV, voltage of grid 4 of -500 V). Light 5 was irradiated to form an electrostatic latent image. At this time, the potential of the photoconductor 1 after the exposure is -70 V
Met. The magnetic one-component toner in the toner reservoir 6 adheres to the surface of the photoconductor 1 by the magnetic force of the fixed magnet 2. At this time, the toner was charged to about −3 μC / g.

Next, the toner layer adhering to the photoreceptor 1 passes before the electrode roller 9 which rotates in the direction of the arrow in FIG. At this time, an 800 V _op (peak-to-peak 1.6 kV) obtained by superimposing a -300 V DC voltage from the AC high-voltage power supply 11 is applied to the electrode roller 9.
AC voltage (frequency 2 kHz) is applied. The toner layer on the photoreceptor 1 moves between the photoreceptor 1 and the electrode roller 9, and the toner adhered to the non-image portion is gradually collected by the electrode roller 9, and the image on the photoreceptor 1 is negative-positive only in the image portion. A toner image is left. The toner collected by the rotating electrode roller 9 is scraped by the scraper 12 and returned to the toner reservoir 6 for reuse in the next image formation. The movement of the toner in the toner reservoir 6 is indicated by a broken line in FIG.

The toner image thus formed on the photoreceptor 1 was transferred to an image receiving paper 14 by a transfer charger 13 and then thermally fixed by a fixing device (not shown) to obtain a print image.

The image quality of the image formed by such a method was evaluated by a copy test. In this copy test, a solid black image was used as a document, and copying was repeated until the number of copies reached 10,000, the image density of the 10,000th copied image was measured with a reflection densitometer (Macbeth), and the image quality was visually evaluated. did. As a result, the copied solid black image was uniform, a high-density image having a density of 1.4 or more could be obtained, and no background fogging occurred in the non-image portion.

(Example 2) The binder resin of the charge transport layer in the laminated electrophotographic photosensitive member was changed from polycarbonate resin to acrylic resin (Dianal BR-80, trade name, manufactured by Mitsubishi Rayon Co., Ltd.). Under the same conditions as in Example 1, a laminated electrophotographic photosensitive member was produced.
The contact angle of the surface of the photoreceptor with pure water was 92 °.

Using this electrophotographic photosensitive member as an electrostatic latent image holder, an image was formed under the same conditions as in Example 1, and a copy test was carried out. As a result, the solid black image was uniform and had a density of 1.0. 4
The above high-density image was obtained. No fogging of the non-image portion occurred.

(Comparative Example 1) The binder resin of the charge transport layer in the laminated electrophotographic photosensitive member was changed from a polycarbonate resin to a urethane resin (trade name: Olestar NL2249E, manufactured by Mitsui Toatsu Chemicals, Inc.). Under the same conditions as in Example 1, a laminated electrophotographic photosensitive member was produced. The contact angle of the photoreceptor surface with pure water is 68 °.
Met.

Using this electrophotographic photosensitive member as an electrostatic latent image holder, an image was formed under the same conditions as in Example 1, and a copy test was carried out. As a result, the solid black image was uniform and had a density of 1 An image with a high density of 0.4 or more was obtained, but background fogging occurred in the non-image area.

Comparative Example 2 Except that 0.5 part by weight of a fluorine-based coating modifier (Aron GF-300, trade name, manufactured by Toa Gosei Chemical Industry Co., Ltd.) was added to the charge transport layer of the laminated electrophotographic photosensitive member. Produced a laminated electrophotographic photosensitive member under the same conditions as in Example 1. The contact angle of the surface of the photoreceptor with pure water was 112 °.

Using this electrophotographic photosensitive member as an electrostatic latent image holder, an image was formed under the same conditions as in Example 1, and a copy test was carried out. As a result, the density of the solid black image was only 1.2. No image was obtained, and the image was of low density.

From these comparisons, it can be seen that the contact angle of the surface of the photoreceptor with pure water greatly affects the density of the image and the occurrence of background fog. In an image forming method including a developing step of adhering a magnetic toner to a photoreceptor by magnetic force and removing extra magnetic toner on the photoreceptor using the magnetic force and electrostatic force, the contact angle is set to 70 ° to 110 °. When set in the range, a clear image with high image density and no ground fog can be obtained. This image forming method
The present invention can be applied to an optical printer such as a copying machine and a laser printer, a laser fax, and the like, and enables high-quality image formation in them.

[0066]

As is apparent from the above description of the embodiments, the electrostatic latent image holder of the present invention has a surface contact angle with pure water of 70 ° to 110 °.
Magnetic toner is magnetically attached to the electrostatic latent image holding member,
This is carried to the magnetic toner collecting section by the movement of the electrostatic latent image holding member, and electrostatic force and magnetic force are applied to an electrode roller arranged opposite to the electrostatic latent image holding member, thereby causing a non-contact on the electrostatic latent image holding member. When developing by a method of collecting the magnetic toner attached to the image area, an appropriate amount of magnetic toner is carried on the electrostatic latent image holding member, and a high-density, high-quality image without background fog is obtained. Can be formed.

Further, in the case where the photosensitive member of the electrostatic latent image holding member is configured by laminating a charge generation layer and a charge transport layer,
Electrophotographic characteristics are good and stable.

Further, when these photoreceptors are formed of an organic substance, they have advantages such as low cost, easy film formation, and no pollution. Further, since the photoreceptor has a high sensitivity in a semiconductor laser light region, a high-precision image can be obtained in a device using a semiconductor laser as an exposure light source such as a laser printer or a laser facsimile.

Further, in the image forming method of the present invention, the image quality can be prevented from deteriorating due to the introduction of the simple developing step having the above-described configuration by using the electrostatic latent image holder, and the cost can be reduced by using a small apparatus. , And high image quality with high density and low fog can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main part of an electrophotographic apparatus for performing an image forming method of the present invention;

FIG. 2 is a conceptual diagram showing a principle of measuring a contact angle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor drum 2 Fixed magnet included in photoreceptor 3 Corona charger 4 Grid electrode 5 Signal light 6 Toner reservoir 7 Magnetic toner 9 Electrode roller 10 Magnet installed inside electrode roller 11 AC high voltage power supply 12 Scraper 13 Transfer electrification Container 14 Receiving paper

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G03G 21/10 G03G 21/00 312 (72) Inventor Masatoshi Maeda 1006 Ojidoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. ( 72) Inventor Tsumugi Kobayashi 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-60-260045 (JP, A) JP-A-1-269945 (JP, A) JP-A Hei 1-243067 (JP, A) JP-A-63-43162 (JP, A) JP-A-5-72890 (JP, A) (58) Fields studied (Int. Cl. ⁶ , DB name) G03G 5 / 00-5/16 G03G 13/08 G03G 15/08-15/08 507

Claims (15)

(57) [Claims] 1. An electrostatic latent image holder on which an electrostatic latent image is written conveys magnetically adhered magnetic toner to a collection unit, and an electrostatic roller and an electrode roller provided with an electrostatic force apply the electrostatic latent image to the collection unit. An electrostatic latent image holding member used in a developing method for recovering a magnetic toner attached to a non-image portion of an image holding member, wherein a contact angle of the surface of the image holding member with pure water is in a range of 70 ° to 110 °. Characteristic electrostatic latent image holder. 2. The electrostatic latent image holding member comprises: a cylindrical conductive support; a charge generation layer containing a charge generation material laminated thereon; and a charge transport layer containing a charge transport material. The electrostatic latent image holder according to claim 1, further comprising: 3. The image forming apparatus according to claim 1, wherein the electrostatic latent image holding member includes at least an organic photoconductor as a part thereof.
3. The electrostatic latent image holding member according to item 1. 4. The electrostatic latent image holder according to claim 2, wherein the charge generation layer of the electrostatic latent image holder contains at least a phthalocyanine pigment. 5. The electrostatic latent image according to claim 2, wherein the charge transport layer of the electrostatic latent image holding member is constituted by an organic resin layer containing a charge transport material and a binder resin. Holding body. 6. An image forming method in which an electrostatic latent image is formed on an electrostatic latent image holding member and the electrostatic latent image is imaged with a magnetic toner. Use a contact angle with water in the range of 70 ° to 110 °,
A magnetic toner is magnetically attached to the electrostatic latent image holding body on which the electrostatic latent image is written, and the magnetic toner is carried to the collection unit by moving the electrostatic latent image holding body, and an electrostatic force is applied. And recovering the magnetic toner adhered to the non-image portion of the electrostatic latent image holding member by an electrode roller having a magnetic force. 7. The electrostatic latent image holding member includes a cylindrical conductive support, a charge generation layer containing a charge generation material laminated thereon, and a charge transport layer containing a charge transport material. 7. The image forming method according to claim 6, wherein the electrostatic latent image holder provided is used. 8. The image forming method according to claim 6, wherein an electrostatic latent image holding member including at least an organic photoconductor is used as the electrostatic latent image holding member. 9. The image forming method according to claim 7, wherein an electrostatic latent image holding member containing at least a phthalocyanine pigment is used in the charge generation layer as the electrostatic latent image holding member. 10. The electrostatic latent image holder, wherein the charge transport layer is an electrostatic latent image holder made of an organic resin layer containing a charge transport material and a binder resin. 8. The image forming method according to item 7. 11. An image forming apparatus comprising: an electrostatic latent image holder that holds and moves an electrostatic latent image; and a unit that images the electrostatic latent image with a magnetic toner. The contact angle of the body surface to pure water is 70
° to 110 °, a fixed magnet that applies a magnetic field to the surface of the electrostatic latent image holding member, a toner reservoir having an opening facing the surface of the electrostatic latent image holding member, An electrode roller that rotates at a position facing the surface of the latent image holding member; a magnet included in the electrode roller; and a voltage applying unit that applies an electrostatic force to the electrode roller. The magnetic toner is magnetically adhered to the electrostatic latent image holding member and carried to the position of the electrode roller, and the electrostatic roller and the non-image portion of the electrostatic latent image holding member are applied with electrostatic force and magnetic force. An image forming apparatus for collecting the magnetic toner attached to the image forming apparatus. 12. The electrostatic latent image holding member comprises a cylindrical conductive support, a charge generation layer containing a charge generation material laminated thereon, and a charge transport layer containing a charge transport material. The image forming apparatus according to claim 11, further comprising: 13. The image forming apparatus according to claim 11, wherein the electrostatic latent image holding member includes at least an organic photoconductor as a part thereof. 14. The charge generation layer of the electrostatic latent image holder,
The image forming apparatus according to claim 12, further comprising at least a phthalocyanine pigment. 15. The charge transport layer of the electrostatic latent image carrier,
The image forming apparatus according to claim 12, comprising an organic resin layer containing a charge transport material and a binder resin.