JPH07319176A - Electrostatic latent image holding body, image forming method and device using the same - Google Patents

Abstract

PURPOSE:To provide an image forming method capable of obtaining a high- quality image high in image density and little in surface staining. CONSTITUTION:A substance whose contact angle of its surface to pure water is within a range form 70 deg. to 110 deg. is used as the electrostatic latent image holding body 1. Then, magnetic toner 7 is magnetically stuck to the holding body 1 and carried to a recovery part by moving the holding body 1, and the magnetic toner stuck to the non-image part of the holding body 1 is recovered by an electrode roller 9 to which electrostatic force and magnetic force are given. In such a case, frictional force and sliding property between the magnetically stuck toner and the holding body 1 are varied by the surface material of the holding body 1, so that a toner amount to be carried and fed to the electrode roller part and toner electrostatic charge amount generated by triboelectrification become different. When such amounts are appropriate, the solid image density is lowered and the surface staining of the non-image part is caused.

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 in an electrophotographic apparatus such as a copying machine, a printer or a facsimile, a method for forming an image using the electrostatic latent image carrier, and an apparatus therefor, and particularly This enables the formation of high quality images.

[0002]

2. Description of the Related Art In recent years, electrophotographic apparatuses have been noted for their advantages such as high speed, low noise, high image quality, and ability to record on plain paper. It is also rapidly becoming popular. In addition, as a recent trend, especially in the field of printers and facsimiles, the mode of use is shifting from office use to personal use, which matches such usage patterns.
There is also a demand for a technique that realizes further downsizing, cost reduction, maintenance-free, and the like for an electrophotographic apparatus.

Generally, 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 an exposure unit to form an electrostatic latent image. continue,
In the developing step, the electrostatic latent image formed on the photoconductor is visualized with toner, which is colored powder, and the toner is transferred and fixed on a copy sheet to form a copy image. on the other hand,
After the residual toner after the transfer is removed by the cleaning process, the photoconductor is neutralized if necessary, and is repeatedly used again in the image forming process.

As described above, the electrophotographic process comprises at least the steps of charging, exposing, developing, transferring and cleaning. The electrostatic latent image carrier used in this process must have excellent electrostatic properties and be a photoreceptor suitable for the electrophotographic process and electrophotographic apparatus in which it is used.

As an electrophotographic photoreceptor, an organic photoreceptor containing an organic photoconductive substance has recently been developed and put into practical use, which has advantages such as easy film formation, inexpensiveness, and no pollution. There is. In particular, in a laser beam printer or a facsimile using a semiconductor laser as an exposure light source, the characteristic of the organic photoconductor having high sensitivity is suitable for the long wavelength region, so that its use is remarkable. Most of the practically used organic photoconductors are laminated organic photoconductors in which a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance are laminated, and a large amount is obtained depending on the constitution of function separation. The characteristics are improved.

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

Further, as an improved technique for 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 installed on the toner carrier with a minute gap from the carrier. Then, the regulating blade regulates the toner in a thin layer and conveys it to the developing portion, where the toner is attached to the image portion of the photoconductor by an AC bias. The technical idea of Japanese Patent Publication No. 63-42256 differs from the above-mentioned US 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 drawbacks. In the cascade development method, the reproducibility of a solid image is poor and the apparatus becomes large and complicated. Further, the developing method described in U.S. Pat. No. 3,866,574 has the drawbacks that the apparatus is required to have high accuracy, its configuration is complicated, and the cost is high. Further, in the jumping developing method, it is necessary to form an extremely uniform thin toner layer on the toner carrier, which is difficult. The developing characteristics of this developing method depend on the toner layer thickness, and if this layer thickness is not formed to be a uniform thin layer, the history of the previous image remains in the toner thin layer on the toner carrier and So-called sleeve ghost development occurs in which an afterimage appears. It also has the drawback that the device is complicated and the cost is high.

Therefore, we have proposed an electrophotographic method and a device therefor capable of realizing high-performance development at a low cost with a small device (for example, Japanese Patent Application No. 3-34).
No. 5990 (Japanese Patent Laid-Open No. 5-72890).

As shown in FIG. 1, this apparatus comprises a photosensitive drum 1 which is an electrostatic latent image holding member, a magnet 2 which is fixed coaxially with the photosensitive member 1, and a corona charger which charges the photosensitive member 1. Three
And a grid electrode 4 for controlling the charging potential of the photoconductor 1,
The toner reservoir 6 for accumulating the magnetic toner 7, the electrode roller 9 having the magnet 10 fixed coaxially therein, the toner flow in the toner reservoir 6 is made smooth, and the toner is crushed by its own weight to be exposed. 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 off the toner on the electrode roller 9, and a photoconductor. A transfer corona charger 13 that transfers the toner image on the image receiving sheet 1 to the image receiving paper 14 is provided. In addition, 5 in FIG. 1 represents signal light for exposure.

At the time of development, the photosensitive member 1 of this apparatus is rotated in the direction of the arrow, the surface of this photosensitive member is charged to -500 V by using the corona charger 3, and then the laser beam 5 is irradiated. 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 photoconductor 1 then passes in front of the electrode roller 9 rotating in the arrow direction.

An alternating voltage of 750 V _0-p (frequency of 1 kHz) superposed with a DC voltage of −350 V is applied to the electrode roller 9 from an AC high voltage power source 11. Therefore, the magnetic toner carried on the photoconductor 1 is collected toward the electrode roller 9, and a negative-positive inverted toner image remains only on the photoconductor 1 on the photoconductor 1. The toner attached 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 photoconductor 1 is transferred to the image receiving paper 14 by the transfer corona charger 13 and then fixed to form a print image.

As described above, in this apparatus, the photoconductor containing the fixed magnet, the toner reservoir arranged so as to face the surface of the photoconductor, and the built-in fixed magnet facing the photoconductor with a predetermined gap therebetween. By using the electrode roller, the magnetic toner supplied from the toner reservoir is attracted by the magnetic force of the fixed magnet and 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, a sleeve ghost does not occur, and the apparatus can be downsized, simplified, and reduced in cost.

[0016]

In this developing method, the magnetic flux density in the fixed magnets inside the photoconductor or the electrode roller, the magnetic pole angles of the two fixed magnets facing each other, the gap between the photoconductor and the electrode roller, and the like are constituted. The above conditions, setting conditions in development such as the charging potential of the photosensitive member and the applied voltage of the electrode roller, and the physical properties of the magnetic toner such as the fluidity of the magnetic toner, the amount of charged electric charge, and the particle size are formed. It has a great influence on the image quality. Therefore, the image quality is optimized by adjusting and selecting these conditions and physical properties. However, other than that, it has been found that the surface properties of the photoconductor have a great influence on the solid image density and the occurrence of toner adhesion (so-called background fog) in the non-image area.

The present invention has been made in view of these viewpoints, and in the above-mentioned image forming method, a static image having a surface physical property capable of obtaining high image density and high image quality with less background fog is provided. An image forming method and an image forming method, which provide an electrostatic latent image holder and which can realize high image quality, downsizing, simplification, and cost reduction of an apparatus by using the electrostatic latent image holder. The purpose is to provide a device.

[0018]

Therefore, in the present invention, an electrostatic latent image holding member on which an electrostatic latent image is written carries magnetic toner adhered magnetically to a collecting portion, so that electrostatic force and magnetic force are generated. The contact angle of pure water on the surface of the electrostatic latent image holder used in the developing method for collecting the magnetic toner adhered to the non-image portion of the electrostatic latent image holder from 70 ° to 1
It is set in the range of 10 °.

The electrostatic latent image carrier is composed of a cylindrical conductive support, a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance, which are laminated on the support. I am configuring.

At least a part of the electrostatic latent image holding member is formed of an organic photoconductor.

Further, at least a phthalocyanine pigment is contained in the charge generation layer of this electrostatic latent image carrier.

The charge transport layer of this electrostatic latent image carrier is composed of an organic resin layer containing a charge transport substance and a binder resin.

Further, in the image forming method of forming an electrostatic latent image on the electrostatic latent image holder and forming the electrostatic latent image with magnetic toner, pure water on the surface is used as the electrostatic latent image holder. A contact angle with respect to is in the range of 70 ° to 110 ° is used, and magnetic toner is magnetically attached to the electrostatic latent image holder on which the electrostatic latent image is written. By moving the body, the magnetic toner is carried to the collecting portion, and the magnetic toner attached to the non-image portion of the electrostatic latent image holding member is collected by the electrode roller which is given an electrostatic force and a magnetic force.

As the electrostatic latent image holding member, a cylindrical conductive support, a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance, which are laminated on the cylindrical conductive support, are provided. The electrostatic latent image carrier provided is used.

As the electrostatic latent image holder, an electrostatic latent image holder containing at least an organic photoconductor as a part thereof is used.

As this electrostatic latent image carrier, an electrostatic latent image carrier containing at least a phthalocyanine pigment in its charge generation layer is used.

Further, as this electrostatic latent image carrier, an electrostatic latent image carrier whose charge transport layer is composed of an organic resin layer containing a charge transport substance and a binder resin is used.

Further, in the image forming apparatus provided with an electrostatic latent image holding member which holds and moves the electrostatic latent image, and means for forming the electrostatic latent image with magnetic toner, the electrostatic latent image holding member is provided. Contact angle of pure water on the surface of 70 to 110 degrees
Set to the range of the above, a fixed magnet that exerts a magnetic field on 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, and the surface of the electrostatic latent image holding member. An electrostatic latent image holder on which an electrostatic latent image is written, provided with an electrode roller that rotates at a position facing the electrode roller, a magnet included in the electrode roller, and a voltage applying unit that applies an electrostatic force to the electrode roller. Magnetic toner is magnetically adhered to the electrode roller and is carried to the position of the electrode roller, and the magnetic toner adhered to the non-image portion of the electrostatic latent image holding member is collected by the electrode roller to which electrostatic force and magnetic force are applied. ing.

As the electrostatic latent image holding member, the electrostatic latent image holding member having the above-mentioned respective constitutional requirements is used.

[0030]

The magnetic toner is magnetically attached to the electrostatic latent image holder on which the electrostatic latent image is written, and the electrostatic latent image holder is moved to carry the magnetic toner to the collecting section and to stop it. When the method of collecting and developing the magnetic toner adhered to the non-image portion of the electrostatic latent image holding member by the electrode roller to which electric power and magnetic force are applied, the magnetically adhered toner and the electrostatic latent image holding member are The frictional force or slipperiness between them varies depending on the surface physical properties of the electrostatic latent image carrier. If the surface physical properties are different, the amount of toner carried and conveyed to the electrode roller portion or the toner charge amount generated by frictional charging is also different. If these amounts are not proper, the solid image density will be reduced, or background fog will occur in the non-image portion, and the image quality will be degraded. That is, when a toner larger than the toner collecting ability of the electrode roller is carried and carried by the electrostatic latent image carrier, background fog occurs, and conversely, when the carried and carried toner is small, the solid image density is increased. Is considered to decrease.

In the present invention, the contact angle of pure water on the surface of the electrostatic latent image carrier is set in the range of 70 ° to 110 ° to optimize the amount of toner carried and conveyed by the electrostatic latent image carrier. It has become. As a result, it is possible to obtain a high-quality image with high image density and less background fog even under various developing conditions of the image forming method described above.

This electrostatic latent image carrier is composed of a cylindrical conductive support, a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance, which are laminated on the support. In this case, the electrophotographic characteristics are good and stable.

When the photosensitive portion of the electrostatic latent image holding member is composed of an organic photosensitive member, the film formation is easy, the cost is low, and it is manufactured without using a substance that causes pollution. be able to.

As the charge generating substance of the organic photoconductor,
When the phthalocyanine pigment is used, an electrostatic latent image carrier having high sensitivity in the long wavelength region of semiconductor laser light can be obtained.

[0035]

EXAMPLES In the present invention, the contact angle of pure water on the surface is 7
An electrophotographic photoconductor of any structure can be used as long as it is an electrostatic latent image carrier in the range of 0 ° to 110 °, but in the examples, the electrophotographic characteristics are good and stable. Therefore, a laminated electrophotography in which a charge generating layer of an organic material containing a charge generating substance and a charge transporting layer of an organic material containing a charge transporting substance are sequentially laminated as a photoreceptor on a cylindrical conductive support. The photoconductor will be described.

The charge generating substance added to the charge generating layer includes phthalocyanine type, azo type, squarylium type,
Organic pigments such as perylene type and cyanine type 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 facsimiles using a semiconductor laser as an exposure light source. Examples of the phthalocyanine-based pigment include metal-free phthalocyanine and various metal phthalocyanines, specifically α-type copper phthalocyanine, β-type copper phthalocyanine, ε-type copper phthalocyanine, τ-type metal phthalocyanine, X-type metal phthalocyanine, and α-type titanyl phthalocyanine. , Β-type titanyl phthalocyanine and the like.

The charge generating layer is formed by adding these charge generating substances and a suitable binder resin to a solvent and dispersing them, and applying the prepared coating solution by a usual coating method and drying. From the viewpoint of electrophotographic characteristics such as sensitivity and repeatability, the film thickness at this time was 1 μm after drying.
Hereafter, it is desirable to form it to preferably about 0.5 μm or less.

As the charge transport material added to the charge transport layer, a compound having an electron donating group such as an alkyl group, an alkoxy group, an amino group or an imide group, althracene,
A polycyclic aromatic compound such as pyrene or phenanthrene or a derivative containing them, a heterocyclic compound such as oxazole, carbazole, pyrazoline, or indole or a derivative containing them, a hydrazone compound, a stilbene compound or the like can be used. The charge transport layer is obtained by dissolving 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 of μm, 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 adhesiveness with other layers, improving the uniformity of the coating film, adjusting the fluidity during coating, and the like. 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. Further, as the solvent, any kind of solvent can be used as long as it dissolves the charge transport substance or the binder resin, but usually, ketones such as methyl ethyl ketone, ethers such as tetrahydrofuran, methylene chloride, carbon tetrachloride. And halogenated hydrocarbons such as benzene, and aromatic hydrocarbons such as toluene are used.

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. Or metal drum, tin oxide,
A plate or a drum of a metal oxide such as indium oxide, or a metal or metal oxide obtained by attaching the metal or metal oxide to various plastic films or drums by vapor deposition, sputtering, laminating, coating, or the like can be used.

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 photoreceptor.

The contact angle of the surface of this laminated electrophotographic photosensitive member with pure water depends on the material composition and surface roughness of the charge transport layer, which is the surface layer, and the drying conditions during coating. This contact angle can be grasped as a numerical value showing 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. This 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 calculates 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 contact angle is The angle (angle with the tangent to the droplet) θ is θ = 2 tan ⁻¹ (h /
r).

The contact angle of pure water on the surface of the electrostatic latent image carrier is set in the range of 70 ° to 110 °. If the contact angle is 110 ° or more, it is not possible to obtain a sufficient solid image density, 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 adhering to the surface of the electrostatic latent image carrier and the electrostatic latent image carrier is small, and the lubricity is too good. It is considered that the amount of toner that adheres to the image carrier and is conveyed decreases, resulting in a decrease in solid image density. On the other hand, when the contact angle of the surface is 70 ° or less, the amount of toner adhering to the electrostatic latent image holding member increases, and the amount exceeds the toner collecting ability of the electrode roller, so that the fog increases. Conceivable.

For image formation, the above-mentioned Japanese Patent Application No. 3-345 is used.
The method proposed in No. 990 is used. After the electrostatic latent image is formed on the electrostatic latent image holder containing the fixed magnet, the magnetic toner is brought into contact with the magnetic latent toner to magnetically adhere the magnetic toner. In this state, the magnetic toner is carried and conveyed to the electrode roller portion.
On the other hand, an AC bias is applied to the electrode roller to remove the magnetic toner adhering to the non-image portion on the electrostatic latent image holder by electrostatic force and magnetic force, and develop.

The magnetic toner used for this image formation contains at least a binder resin and a magnetic material as constituent components, and if necessary, a colorant, a charge control agent, a release agent, a fluidizing agent, and a second external additive substance. Is added. A styrene acrylic resin, a polyester resin, or the like can be used as the binder resin, and if necessary, other known polymers or copolymers can also be used. Further, as the magnetic material to be mixed, metal powder such as iron, manganese, nickel and cobalt, and ferrite such as iron, manganese, nickel, cobalt and zinc can be used. The amount of magnetic material added 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, and when the addition amount is 60% by weight or more, the toner charge amount decreases and the image quality tends to deteriorate.

As the colorant and the charge control agent, carbon black, iron black, graphite, nigrosine, a metal complex of azo dye, phthalocyanine blue, cerco oil blue, DuPont oil red, aniline blue, benzidine yellow, rose bengal or Pigments or dyes such as mixtures thereof can be used.

The release agent may be polyethylene or polypropylene, and the external additive may be hydrophobic silica, titania,
Inorganic fine powder such as alumina and zirconia, and tin oxide, strontium titanate, barium titanate, tungsten carbide and the like can be used as an abrasive and a fluidity aid, and further, an electrification aid, a cleaning aid and the like. Fine powders of organic materials and other types of additives can also be added for the purpose.

Next, specific examples of the electrostatic latent image carrier, the image forming method and the apparatus for carrying out the method will be described in detail.

Example 1 Two parts by weight of 2 parts by weight of τ type metal-free phthalocyanine (manufactured by Toyo Ink Mfg. Co., Ltd.) and 2 parts by weight of 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 by a ball mill for 4 hours, the dispersion was dip-coated on an aluminum drum having an outer diameter of 30 mm, 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
Parts by weight and 1 part by weight of polycarbonate resin (trade name Iupilon Z-300 manufactured by Mitsubishi Gas Chemical Industry Co., Ltd.) in 9 parts by weight of methylene chloride are dip-coated on the charge generation layer at 110 ° C. Film thickness of about 20μm after drying for 2 hours
The charge-transporting layer was formed to obtain a laminated electrophotographic photosensitive member.

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

An image was formed by using this electrophotographic photosensitive member as the electrostatic latent image carrier 1 of the image forming apparatus shown in FIG.

As the magnetic toner, a negatively chargeable magnetic one-component toner having a styrene-acrylic resin as a binder and having an average particle diameter of about 7 μm was used. The composition of this magnetic one-component toner is 70 parts by weight of styrene-acrylic resin and 25 parts of ferrite.
Parts by weight, carbon black 3 parts by weight, metal oxycarboxylic acid complex 2 parts by weight, and further having a particle size of 0.02 μm
0.4 part by weight of colloidal silica is externally added.

The magnetic flux density on the surface of the photosensitive member 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 in degrees. Further, the photoconductor 1 is rotated at a peripheral speed of 65 mm / s in the direction of the arrow in the drawing, the electrode roller 9 is set to have a diameter of 16 mm, and the peripheral speed is 40 mm / s in a direction opposite to the traveling direction of the photoconductor. It is rotated 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 the corona charger 3 (applied voltage -5.3 kV, grid 4 voltage -500 V), and then the photoreceptor 1 is laser-charged. Light 5 was irradiated to form an electrostatic latent image. At this time, the potential of the photoreceptor 1 after exposure is -70V.
Met. The magnetic one-component toner in the toner reservoir 6 is attached 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 attached to the photoconductor 1 passes in front of the electrode roller 9 which rotates in the direction of the arrow in the figure due to the rotation of the photoconductor. At this time, 800 V _op (peak-to-peak 1.6 kV) in which a DC voltage of -300 V was superposed on the electrode roller 9 from the AC high-voltage power supply 11.
AC voltage (frequency 2 kHz) is applied. The toner layer on the photoconductor 1 moves between the photoconductor 1 and the electrode roller 9, and the toner adhering to the non-image portion is gradually collected by the electrode roller 9, and the negative-positive reversal is made only on the image portion on the photoconductor 1. A toner image is left behind. The toner collected by the rotating electrode roller 9 is reused for the next image formation, and is scraped off by the scraper 12 and returned to the toner reservoir 6. The movement of the toner in the toner reservoir 6 is shown by the broken line in FIG.

The toner image thus formed on the photoreceptor 1 was transferred to the image receiving paper 14 by the transfer charger 13 and then heat-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, using a solid black image as an original, copying was repeated until the number of copies reached 10,000, and the image density of the 10,000th copy image was measured with a reflection densitometer (Macbeth Co.), and the image quality was visually evaluated. did. As a result, the solid black image copied was uniform, a high-density image having a density of 1.4 or more could be obtained, and no background fog was generated in the non-image area.

(Example 2) The binder resin of the charge transport layer in the laminated electrophotographic photosensitive member was changed from polycarbonate resin to acrylic resin (trade name DIANAL BR-80 manufactured by Mitsubishi Rayon Co., Ltd.), and all other points were used. A laminated electrophotographic photosensitive member was produced under the same conditions as in Example 1.
The contact angle of pure water on the surface of this photoreceptor was 92 °.

Using this electrophotographic photosensitive member as an electrostatic latent image carrier, an image was formed under the same conditions as in Example 1, and a copying test was carried out. The result is that a solid black image is uniform and the density is 1. Four
The above high density image was obtained. Further, the background fog in the non-image area did not occur.

Comparative Example 1 The binder resin of the charge transport layer in the laminated electrophotographic photosensitive member was changed from polycarbonate resin to urethane resin (Orestar NL2249E, trade name, manufactured by Mitsui Toatsu Chemicals, Inc.), and all other points were used. A laminated electrophotographic photosensitive member was produced under the same conditions as in Example 1. The contact angle of pure water on the surface of this photoconductor is 68 °.
Met.

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

Comparative Example 2 0.5 parts by weight of a fluorine-based coating modifier (trade name: Aron GF-300 manufactured by Toagosei Kagaku Kogyo Co., Ltd.) was added to the charge transport layer of the laminated electrophotographic photoreceptor. A multilayer electrophotographic photosensitive member was manufactured under the same conditions as in Example 1. The contact angle of pure water on the surface of this photoreceptor was 112 °.

Using this electrophotographic photoreceptor as an electrostatic latent image carrier, an image was formed under the same conditions as in Example 1 and a copy test was carried out. The result is that the solid black image has a density of 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 photoconductor to pure water has a great influence on the image density and the occurrence of background fog. In the image forming method including a developing step in which magnetic toner is attached to the photoconductor by magnetic force and excess magnetic toner on the photoconductor is removed by using magnetic force and electrostatic force, the contact angle is 70 ° to 110 °. When the range is set to, the image density is high and a clear image without background fog can be obtained. This image forming method is
It can be applied to a photocopier, an optical printer such as a laser printer, a laser fax, and the like, and enables high-quality image formation in them.

[0066]

As is clear from the above description of the embodiments, the electrostatic latent image carrier of the present invention has the contact angle of pure water on the surface in the range of 70 ° to 110 °.
Magnetic toner is magnetically attached to the electrostatic latent image carrier,
This is carried to the magnetic toner collecting portion by the movement of the electrostatic latent image holding member, and electrostatic force and magnetic force are applied to the electrode roller arranged facing the electrostatic latent image holding member to apply the non-contact When developing by the method of collecting the magnetic toner attached to the image area, an appropriate amount of magnetic toner is carried on the electrostatic latent image holder, resulting in a high-quality image with high density and no background fog. Can be formed.

Further, in the case where the photosensitive member of the electrostatic latent image holding member is constituted by laminating the charge generating layer and the charge transporting layer,
The electrophotographic characteristics are good and stable.

Further, when these photoconductors are made of an organic substance, there are advantages such as cost reduction, easy film formation, and no pollution. Further, since this photosensitive member has a high sensitivity in the semiconductor laser light region, it is possible to obtain a highly accurate image in a device such as a laser printer or a laser facsimile using a semiconductor laser as an exposure light source.

Further, in the image forming method of the present invention, the deterioration of the image quality due to the introduction of the simple developing process having the above-mentioned constitution can be avoided by using the electrostatic latent image holding member, and the small apparatus can reduce the cost. It is possible to realize both the image formation in step 1 and the high image quality with high density and low background fog.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of an electrophotographic apparatus for carrying out 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]

 1 Photoconductor drum 2 Fixed magnet contained in the photoconductor 3 Corona charger 4 Grid electrode 5 Signal light 6 Toner reservoir 7 Magnetic toner 9 Electrode roller 10 Magnet installed inside the electrode roller 11 AC high voltage power supply 12 Scraper 13 Transfer charge Container 14 Receiving paper

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G03G 15/08 507 C 21/10 (72) Inventor Masatoshi Maeda 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita (72) Inventor Tsumugi Kobayashi 1006, Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (15)

[Claims] 1. An electrostatic latent image carrier on which an electrostatic latent image is written conveys magnetic toner magnetically adhered to a collecting portion, and the electrode roller to which electrostatic force and magnetic force are applied is the electrostatic latent image. An electrostatic latent image carrier used in a developing method for recovering magnetic toner adhered to a non-image portion of an image carrier, the contact angle of pure water on the surface of which is in the range of 70 ° to 110 °. Characteristic electrostatic latent image holder. 2. The electrostatic latent image carrier comprises a cylindrical conductive support, a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance, which are laminated on the cylindrical conductive support. The electrostatic latent image holder according to claim 1, further comprising: 3. The electrostatic latent image carrier comprises at least an organic photoconductor as a part thereof.
The electrostatic latent image carrier according to item 1. 4. The electrostatic latent image carrier according to claim 2, wherein the charge generation layer of the electrostatic latent image carrier 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 carrier is composed of an organic resin layer containing a charge transport substance and a binder resin. Holding body. 6. An image forming method, wherein an electrostatic latent image is formed on an electrostatic latent image holding member, and the electrostatic latent image is imaged by magnetic toner. In the image forming method, the electrostatic latent image holding member has a pure surface. Use a contact angle with water in the range of 70 ° to 110 °,
Magnetic toner is magnetically attached to the electrostatic latent image holder on which the electrostatic latent image is written, and the electrostatic latent image holder is moved to carry the magnetic toner to the collecting portion, and electrostatic force is applied. An image forming method, characterized in that the magnetic toner adhered to the non-image portion of the electrostatic latent image holding member is collected by an electrode roller which is given a magnetic force. 7. A cylindrical conductive support, a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance, which are stacked on the cylindrical conductive support, as the electrostatic latent image holding member. The image forming method according to claim 6, wherein an 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 as a part thereof is used as the electrostatic latent image holding member. 9. The image forming method according to claim 7, wherein, as the electrostatic latent image carrier, an electrostatic latent image carrier containing at least a phthalocyanine pigment in its charge generation layer is used. 10. The electrostatic latent image holding member is used as the electrostatic latent image holding member, wherein the charge transporting layer is an organic resin layer containing a charge transporting substance and a binder resin. 7. The image forming method described in 7. 11. An image forming apparatus comprising: an electrostatic latent image holding member that holds and moves an electrostatic latent image; and a unit that forms the electrostatic latent image with magnetic toner. The contact angle of pure water on the body surface is 70
Is set in the range of 90 ° to 110 °, a fixed magnet that exerts a magnetic field on 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, and the electrostatic 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 are provided to write an electrostatic latent image. The magnetic toner is magnetically attached to the electrostatic latent image holder and carried to the position of the electrode roller, and the non-image portion of the electrostatic latent image holder is held by the electrode roller to which electrostatic force and magnetic force are applied. An image forming apparatus, which collects magnetic toner attached to an image forming apparatus. 12. The electrostatic latent image carrier comprises a cylindrical conductive support, a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance, which are laminated on the cylindrical conductive support. The image forming apparatus according to claim 11, further comprising: 13. The image forming apparatus according to claim 11, wherein the electrostatic latent image carrier includes at least an organic photoconductor as a part thereof. 14. The charge generation layer of the electrostatic latent image carrier,
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 comprises:
The image forming apparatus according to claim 12, comprising an organic resin layer containing a charge transport material and a binder resin.