JP3372617B2 - Electrostatic image developing developer, image forming method and electrophotographic apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a developer for developing an electrostatic charge image for visualizing an electrostatic charge image in an image forming method such as electrostatic printing, an image forming method using the electrostatic charge image developer, and an electrophotographic apparatus.

More specifically, the electrostatic latent image formed on the surface of the electrostatic image carrier is developed with a developer to form a developed image, and a transfer means is brought into contact with the surface of the electrostatic image carrier via a transfer material. The present invention relates to an electrostatic charge image developing developer used in an image forming method having a step of electrostatically transferring the developed image to a transfer material, an image forming method using the developer, and an electrophotographic apparatus.

[0003]

2. Description of the Related Art In an image forming apparatus including a step of electrostatically transferring a transferable developed image formed on the surface of an electrostatic charge image carrier to a sheet-like transfer material composed mainly of paper, a rotary cylinder, Using an electrostatic charge image carrier that runs endlessly such as an endless belt, press the biased transfer means against the transfer means to pass the transfer material between them, and develop the developed image on the electrostatic charge image carrier side. Those configured to transfer to a transfer material,
For example, a device as disclosed in Japanese Patent Laid-Open No. 59-46664 has already been proposed.

In such an apparatus, the transfer material is adjusted by adjusting the pressure contact force of the roller as the transfer means to the electrostatic image carrier, as compared with the transfer means using corona discharge which has been widely used in the past. Of the electrostatic charge image carrier can be expanded, and the transfer material is positively pressed and supported at the transfer site. Therefore, the transfer material is not transferred due to a synchronization failure or a loop or curl existing in the transfer material. There is little risk of misalignment, the generation of ozone due to discharge is significantly suppressed, the transfer material conveyance path is shortened with the recent miniaturization of this type of image forming apparatus, the electrostatic charge image carrier is miniaturized, and the office environment is good. Although it is easy to meet the demands for higher efficiency and ecology, on the other hand, in a device that performs transfer by contact, transfer current is supplied from the contact part, so some pressure is transferred. It is necessary to pressurize the location. When the contact portion pressure is applied, the developed image on the surface of the electrostatic charge image bearing member is also applied with pressure and aggregation occurs.

Further, when the surface of the electrostatic charge image carrier is made of resin, close contact occurs between the developer agglomerates and the electrostatic charge image carrier, which hinders the transfer to the transfer material, resulting in an extreme In such a case, a phenomenon occurs in which the portion of the developer having strong adhesion is not transferred at all and the image is lost.

This phenomenon becomes particularly noticeable in the line portion of 0.1 to 2 mm. This is because the line portion is edge-developed, the amount of developer is large, aggregation due to pressure is likely to occur, and defects due to transfer are likely to occur. The image output at this time is a copy in which the image is formed only on the contour portion, and is called "transfer void". With reference to FIGS. 1 and 2, voids in transfer will be described with an example. FIG. 1 is an image transferred by corona transfer, and FIG. 2 is a hollow image transferred by roller contact transfer.

The "transfer void" is particularly noticeable on a thick paper of 100 g / cm ² or more, an OHP film having a high smoothness, a second side copy, and the like. It is conceivable that since the transfer material is thick in thick paper and film, the effect on the transfer electric field is small and the pressure is strong so that the hollow portion may be easily lost.

When copying the second side, when passing through the fixing device when forming the image on the first side, a releasing agent contained for preventing offset from the fixing device is attached to the transfer material, and toner is used when copying the second side. It is considered that since the contact between the transfer material and the transfer material is hindered, hollow defects are likely to occur.

As described above, in the case of the transfer device using the contact member, there are many advantages such as miniaturization and low power consumption, but the conditions for the transfer material are narrowed.

Further, in recent years, with the widespread use of image forming apparatuses such as electrophotographic copying machines, their applications have been widespread and the demands on their image quality have become strict. When copying images such as ordinary documents and books, it is required to reproduce extremely fine and faithfulness without breaking even fine characters.
Is a problem that needs to be improved.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developer for developing an electrostatic charge image, an image forming method using the developer and an electrophotographic apparatus which can solve the above-mentioned conventional problems. And

That is, in the present invention, the electrostatic latent image formed on the surface of the electrostatic charge image carrier is developed with a developer to form a developed image, and a transfer means is formed on the surface of the electrostatic charge image carrier through a transfer material. A developer for developing an electrostatic charge image, which is faithful to the electrostatic charge latent image and can obtain a high-quality image when an image is formed by electrostatically transferring the developed image to a transfer material by bringing it into contact with the transfer material. An object is to provide an image forming method using a developer and an electrophotographic apparatus.

According to the present invention, the electrostatic latent image formed on the surface of the electrostatic charge image carrier is developed with a developer to form a developed image, and the electrostatic charge image carrier is transferred to the surface of the electrostatic charge image carrier through a transfer material. For electrostatic charge image development in which development such as "dropout in transfer" does not occur or the development is suppressed when the developed image is electrostatically transferred to a transfer material by abutting against An object is to provide a developer, an image forming method using the developer, and an electrophotographic apparatus.

Further, in the present invention, the electrostatic latent image formed on the surface of the electrostatic image carrier is developed with a developer to form a developed image, and a transfer means is provided on the surface of the electrostatic image carrier via a transfer material. When an image is formed by electrostatically transferring the developed image to a transfer material by contacting it, even if various transfer materials such as thick transfer paper are used, the development such as "dropout in transfer" does not occur, or the development It is an object of the present invention to provide an electrostatic charge image developing developer capable of suppressing the above phenomenon, an image forming method using the developer, and an electrophotographic apparatus.

[0015]

The developer for developing an electrostatic charge image of the present invention has a contact pressure of 20 g between the electrostatic charge image carrier and the transfer means contacting via the transfer material in the transfer step.
/ Cm or more, which is a developer used in an image forming method, i) contains a binder resin and a magnetic material, and has a weight average particle diameter.
Magnetic toner particles but Ru 7~10μm der, ii) magnetic toner particles 100 parts by weight of metal nitride fine particles and having an average particle size of 0.5 to 5.0μm 0.01 to 5.0 parts by weight with respect to iii) By containing the silica fine powder, the above-mentioned object can be achieved.

The image forming method of the present invention comprises a step of forming an electrostatic latent image on the surface of an electrostatic image carrier, a step of developing the electrostatic latent image with a developer to form a developed image, and the developed image. In the image forming method, there is provided a transfer step of electrostatically transferring the developed image to the transfer material while contacting the transfer means with a contact pressure of 20 g / cm or more on the surface of the electrostatic charge image carrier having developer, i) contains a binder resin and a magnetic material, the weight average particle size of 7~10μm der Ru magnetic toner particles, ii) 0.01 to 5.0 relative to the magnetic toner particles 100 parts by weight The above object is achieved by including parts by weight of metal nitride fine particles having an average particle diameter of 0.5 to 5.0 μm and iii) silica fine powder.

The electrophotographic apparatus of the present invention comprises an electrostatic charge image carrier, an electrostatic charge latent image forming means for forming an electrostatic charge latent image on the surface of the electrostatic charge image carrier, and developing the electrostatic charge latent image. A developing unit that holds a developer for forming a developed image, and a contact pressure of 20 g / cm or more via the transfer material to the electrostatic image carrier for electrostatically transferring the developed image to the transfer material. In an electrophotographic apparatus having a transfer means provided so as to be capable of contacting, the developer held in the developing means is i)
Contains a binder resin and a magnetic material, and has a weight average particle size of 7 to 1
0μm der Ru magnetic toner particles, ii) 0 to 0.01 to 5.0 parts by weight per 100 parts by weight of the magnetic toner particles.
The above object is achieved by including metal nitride fine particles having an average particle diameter of 5 to 5.0 μm and iii) silica fine powder.

The reason why the developer for developing an electrostatic image of the present invention can achieve the above-mentioned object is not clear, but it is presumed as follows.

That is, in the developer for developing an electrostatic charge image of the present invention, metal nitride fine particles having an average particle size of 0.5 to 5.0 μm (preferably 0.7 to 4.5 μm) are added to 100 parts by weight of magnetic toner particles. One of the features is that the content is 0.01 to 5.0 parts by weight (preferably 0.03 to 3.5 parts by weight). Since the metal nitride particles adhere to the surface of the toner particles in the developer in the transfer step when the image formation according to the present invention is performed and the metal nitride fine particles have almost no triboelectrification ability, an electrostatic charge image carrier Prevents adhesion between the toner particles and the toner particles due to electrostatic attraction, and improves the releasability of the toner particles from the electrostatic image carrier, so that the transfer means can contact the surface of the electrostatic image carrier through the transfer material. Even if it is provided, it is considered that the developed image formed on the surface of the electrostatic image bearing member can be satisfactorily transferred to the transfer material. Further, since the transfer is good, no load is applied to the cleaner, and scratches on the surface of the electrostatic charge image bearing member do not occur.

When the average particle diameter of the metal nitride fine particles according to the present invention is less than 0.5 μm, the function as the spacer particles between the electrostatic image carrier and the toner particles as described above becomes extremely weak. The effect on "transfer failure" is not so remarkable, and when it is larger than 5.0 µm, the toner particles are less likely to be present on the electrostatic image carrier, and the effect on "transfer failure" is reduced.

The amount of the metal nitride fine particles added to the developer is 0.01 with respect to 100 parts by weight of the toner particles.
If it is less than 5 parts by weight, the effect against "blurring during transfer" is small, and if it is more than 5.0 parts by weight, the amount of charge of the developer becomes unstable and fogging occurs in white areas of the image. In addition, so-called “scattering”, which is a state in which toner particles are scattered on the image, occurs.

The average particle size of the metal nitride fine particles according to the present invention can be defined by various methods, but in the present invention, electron micrographs were used.

That is, a photograph is taken with an electron microscope S800 (manufactured by Hitachi, Ltd.) at a magnification of 10000 to 20000 times, and 100 to 200 pieces are randomly extracted from the metal nitride fine particles of the photographed photograph, and a caliper or the like is used. The respective diameters were measured using a measuring instrument and the averaged value was defined as the average particle size of the metal nitride fine particles.

The metal nitride fine particles according to the present invention are prepared by a method of treating fine metal powder in nitrogen at a high temperature, a method of heating a mixture of metal oxide powder and carbon to 1000 to 1200 ° C. in nitrogen, and the like. Alternatively, a so-called nitriding furnace, a Franck-Caro type nitriding furnace, an N-type furnace, a D-type furnace or the like may be used.

The particle size of the metal nitride fine particles is controlled by a method of controlling the particle size of the metal oxide powder used as a raw material and crushing after nitriding with a ball mill or the like.

The metal nitride fine particles according to the present invention include various metal nitrides such as titanium nitride fine particles, vanadium nitride fine particles, zirconia nitride fine particles, and chromium nitride fine particles. The metal nitride fine particles may be surface-treated with various coupling agents or the like.

As the binder resin for the toner particles according to the present invention, homopolymers of styrene such as polystyrene and polyvinyltoluene and their substitution products; styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-
Vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer Polymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer Polymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer Styrene-based copolymers such as coalesce: Methyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, tempel resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, Paraffin wax, carnauba wax and the like can be used alone or in combination.

As the magnetic fine particles as a magnetic material contained in the magnetic toner according to the present invention, a substance that is magnetized by being placed in a magnetic field is used, and a powder of a ferromagnetic metal such as iron, cobalt or nickel, Or magnetite, γ-F
Alloys and compounds such as e ₂ O ₃ and ferrite can be used.

The toner according to the present invention may contain a charge control agent, if necessary.

As the negative charge control agent, a metal complex salt of a monoazo dye, a metal complex salt of salicylic acid, an alkylsalicylic acid, a dialkylsalicylic acid, or a naphthoic acid can be used.

As the positive charge control agent, nigrosine and its modified product, tributylbenzylammonium-1.
-Quaternary ammonium salt such as hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, dibutyltin oxide, dioctyltin oxide, diorganotin oxide such as dicyclohexyltin oxide, dibutyltin borate, dioctyltin borate, dicyclohexyltin borate And the like diorgano tin borate can be used.

As the coloring material which can be further added to the toner particles according to the present invention, conventionally known carbon black, copper phthalocyanine, etc. can be used.

The developer of the present invention is a silicic acid fine powder (silica).
Mosquito fine powder) Ru with added. As the silicic acid fine powder, both so-called dry process produced by vapor phase oxidation of a silicon halogen compound or dry silica called fumed silica and so-called wet silica produced from water glass can be used. , fewer silanol groups on the inner surface and the fine silica powder, and Na ₂ O, is more dry silica without producing residues such as SO _^2-3 preferred.

Further, in the case of dry silica, it is possible to obtain a composite fine powder of silica and another metal oxide by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound in the manufacturing process. And includes them.

The particle size is 0.0 as the average primary particle size.
The particle size is preferably in the range of 01 to 2 μm, and particularly preferably, fine silica powder in the range of 0.002 to 0.2 μm is used.

For the hydrophobizing treatment, conventionally known hydrophobizing agents and methods such as silicone oil are used.

The developer of the present invention may further contain other additives such as a fixing aid (for example, low molecular weight polyethylene) or a metal such as tin oxide as a conductivity-imparting agent, as long as it does not have a substantial adverse effect. An oxide or the like may be added.

In the production of the toner particles according to the present invention, the constituent materials are well kneaded by a heat kneader such as a hot roll, a kneader or an extruder, and then mechanically ground,
A method of obtaining by classification, or a method of obtaining a material by dispersing the material in a binder resin solution and then spray-drying, or a method of mixing a predetermined material with a monomer that constitutes the binder resin to obtain an emulsion suspension. After that, each method can be applied, such as a polymerization method for obtaining a toner by polymerizing the toner.

The magnetic toner particles according to the present invention have a weight average particle diameter of 7 to 10 μm. In order to efficiently achieve homogenization of the developer layer, it is preferable that the magnetic toner particles having a particle diameter of 5 μm to 10.8 μm are included in an amount of 50 to 95% by number.

The method for measuring the particle size distribution of the magnetic toner according to the present invention will be described below.

The particle size distribution can be measured by various methods, but in the present invention, a Coulter counter multisizer was used.

That is, a Coulter counter Multisizer II type (manufactured by Coulter) is used as a measuring device, and an interface (manufactured by Nikkaki) for outputting number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) are connected. Then, as the electrolyte, a 1% NaCl aqueous solution is prepared using special grade or primary grade sodium chloride.
As the measuring method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and measurement was performed using a Multisizer II type Coulter Counter using a 100 μm aperture as an aperture. The volume and number of magnetic toner particles were measured to calculate the volume distribution and number distribution. Then, the weight-based weight average diameter (D4) was determined from the volume distribution.

In the transfer step according to the present invention, the contact pressure of the transfer means contacting the electrostatic charge image carrier through the transfer material is such that the linear pressure calculated by the following equation is 20 g / cm or more.
There is .

[0044]

[Chemical 1]

If the linear pressure as the relevant contact pressure is less than 20 g / cm, transfer failure of the transfer material and transfer failure due to insufficient transfer current may occur, which is not preferable.

Examples of the transfer means used in the present invention include a transfer roller as shown in FIG. FIG. 3 is a schematic side view of a main part of an apparatus used for a typical image formation of this type. The apparatus shown in FIG.
A cylindrical electrostatic charge image carrier (hereinafter referred to as a photoconductor) 101 that rotates in the direction of arrow A, and a conductive transfer roller 103 as a transfer unit that abuts on this are arranged.

A primary charger for uniformly charging the surface of the photoconductor 101, and an optical image such as image-modulated laser light or reflected light from the original are projected on the charged surface. There are provided an exposure unit that attenuates the potential of the portion to form an electrostatic latent image, a developing unit, a cleaning member that removes residual toner remaining on the surface of the photoconductor after transfer, and other members necessary for image formation. Needless to say, they are all omitted.

The transfer roller 103 comprises a core metal 103a and a conductive elastic layer 103b, and the conductive elastic layer 103b has a volume resistance of about 10 ⁶ to 10 ¹⁰ Ω · cm such as urethane and EPDM in which a conductive material such as carbon is dispersed. Made of elastic material. A bias is applied to the core metal 103a by a constant voltage power supply 114. The bias conditions are a current value of 0.1 to 50 μA and a voltage (absolute value) of 100 to 50.
00V (more preferably 500 to 40,000V) is preferable. The pressure of the transfer means onto the photoconductor 101 is normally 1
This is done by pressurizing the end bearing of 03a.

The present invention is particularly effective for an image forming apparatus in which the surface of the photoconductor (electrostatic image bearing member) is an organic compound.

When the organic compound forms the surface layer of the photoconductor, the adhesiveness to the binder resin contained in the toner particles is better than that of other photoconductors using the inorganic material, and particularly, This is because when a material of the same quality is used for the surface layer, chemical bonding is likely to occur at the contact, and thus the transferability tends to be lower.

Photoreceptor used in the present invention (electrostatic image bearing member)
Examples of the surface substance include silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate, but are not limited thereto, and other monomers or Copolymerization, blending, etc. between the exemplified resins can also be used.

The magnetic developer of the present invention can faithfully reproduce even the fine lines of the latent image formed on the photoconductor, and can also reproduce halftone dots and dot latent images such as digital ones. It provides an image with excellent gradation and resolution.

FIG. 4 is an explanatory view schematically showing the structure of the electrophotographic apparatus of the present invention, and only one example of the electrophotographic apparatus and the image forming method of the present invention will be described with reference to the explanatory view.

The surface of the photoconductor is negatively charged by the charging means 102 having the power supply section (voltage applying means) 115, and a digital latent image is formed by image scanning by exposure 105 with laser light as an electrostatic latent image forming means. . The latent image is reversely developed with a negatively chargeable one-component magnetic developer 110 in a developing device (developing means) 109 having a developing sleeve 104 containing a magnetic blade 111 and a magnet. In the developing section, an AC bias, a pulse bias and / or a DC bias are applied between the conductive substrate of the photoconductor 101 and the developing sleeve 104 by the bias applying means 112. When the transfer paper P as the transfer material is conveyed and reaches the transfer portion, the transfer roller 10 as the transfer means is formed.
The developing image on the surface of the photoconductor is electrostatically transferred onto the transfer paper P by being charged by the voltage applying unit 114 from the back surface (the side opposite to the photoconductor side) of the transfer paper P by 3. Photoconductor 101
The transfer paper P separated from is a heating and pressure roller fixing device 1
At 07, a fixing process is performed to fix the transferred developed image on the transfer paper P.

The one-component developer remaining on the photoreceptor 101 after the transfer step is removed by the cleaning device 108 having a cleaning blade. Photoconductor 1 after cleaning
No. 01 is erased by the erase exposure 106, and the process starting from the charging process by the charging member 102 is repeated again.

The photosensitive member (electrostatic image bearing member) 101 has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. The non-magnetic cylindrical developing sleeve 104, which is a toner carrier, rotates so as to move in the same direction as the surface of the photoconductor 101 in the developing section.
Inside the developing sleeve 104, a multi-pole permanent magnet (magnet roll) which is a magnetic field generating means is arranged so as not to rotate. The one-component insulating magnetic developer 110 in the developing device 109 as a developing unit is applied on the non-magnetic cylindrical surface, and the friction between the surface of the developing sleeve 104 and the toner particles causes the toner particles to have a negative triboelectric charge, for example. Is given. Furthermore, iron magnetic doctor blade 111
Close to the cylindrical surface (spacing 50 μm to 500 μm),
The developer layer is made thin (30 μm to 300 μm) by arranging it so as to face one magnetic pole position of the multi-pole permanent magnet.
m) and uniformly regulate the photosensitive member 101 in the developing unit.
And a developer layer thinner than the gap between the developing sleeve 104 and the developing sleeve 104 is formed so as not to contact with each other. By adjusting the rotational speed of the developing sleeve 104, the surface speed of the sleeve is made substantially equal to or close to the speed of the electrostatic image holding surface. Instead of iron as the magnetic doctor blade 111, a permanent magnet may be used to form the opposing magnetic poles.

When the toner particles are transferred in the developing portion, the toner particles are transferred to the photosensitive member 1 by the action of the electrostatic force on the surface of the photosensitive member 101 and the AC bias or the pulse bias.
01 is transferred to the electrostatic image side.

Instead of the magnetic doctor blade 111,
The developer may be applied to the surface of the photoreceptor by controlling the layer thickness of the developer layer by pressing with an elastic blade formed of an elastic material such as silicon rubber.

[0059]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention.
All parts in the following formulations are parts by weight.

Example 1 Styrene / butyl acrylate copolymer (copolymerization ratio 82/18, number average molecular weight (Mn) 6000, weight average molecular weight (Mw) 16000) 30 parts styrene / butyl acrylate copolymer (Copolymerization ratio 80/20, number average molecular weight (Mn) 31,000, weight average molecular weight (Mw) 140,000) 70 parts-Magnetite 90 parts-Chromium complex of dialkylsalicylic acid 2 parts-Low molecular weight polypropylene 3 parts

The above materials were mixed and melt-kneaded with a roll mill. After cooling, the mixture was pulverized and classified to obtain a black powder having a weight average diameter of 8.5 μm. An average particle size of 2.1 is added to 100 parts of this black powder.
0.5 parts of titanium nitride fine particles of μm and 0.6 parts of hydrophobic silica fine powder treated with hexamethyldisilazane as a fluidizing agent were externally added by a Henschel mixer to obtain a developer 1.

A digital copying machine G manufactured by Canon Inc. is used as the developer.
The P-55 was used in the electrophotographic apparatus shown in FIG. 4, which was modified as a transfer means using a transfer roller that abuts against the electrostatic image carrier as shown in FIG. 3, and the temperature / humidity was low at 25 ° C./5% Rh. Under the environment, images were continuously printed on 10,000 sheets.

The developing conditions were as follows.

○ The closest gap between the photosensitive member and the developing sleeve:
Approximately 300 μm ○ Closest gap between magnetic blade and developing sleeve: Approximately 23
0 μm ○ Thickness of developer on developing sleeve: About 100 μm ○ Development bias: AC bias (Vpp 1600V, frequency 1800Hz), DC bias (-600V)

The transfer conditions were as follows.

○ Surface rubber hardness of transfer roller: 24 ° ○ Transfer current: 2.5 μA ○ Transfer voltage: +2000 V ○ Contact pressure: 60 g / cm (linear pressure) ○ Conductive elastic layer of transfer roller: Conductive carbon Dispersed EPDM ○ Volume resistance of conductive elastic layer: 10 ⁸ Ω · cm

The results are shown in Table 1 as follows:
The image densities were high on both sheets, and as shown in FIG. 1, there was no occurrence of "blurring of transfer", and there was no fog or scattering. Further, a high-quality halftone image was obtained without scratches on the photoconductor even after printing 10,000 images.

The evaluation of "blank transfer" was made by printing on an OHP film.

Example 2 Developer 2 was obtained in the same manner as in Example 1, except that the addition amount of the titanium nitride fine powder was changed to 3 parts. Table 1 shows the results of evaluations performed in the same manner as in Example 1.

Example 3 In Example 1, the amount of titanium nitride fine powder added was 0.05.
Developer 3 was obtained in the same manner as in Example 1 except that the parts were changed. The results of evaluation of this in the same manner as in Example 1 are shown in Table 1.
Shown in.

Example 4 A developer 4 was obtained in the same manner as in Example 1 except that the titanium nitride fine particles having an average particle diameter of 2.1 μm were replaced with titanium nitride fine particles having an average particle diameter of 4.5 μm. . Table 1 shows the results of evaluations performed in the same manner as in Example 1.

Example 5 A developer 5 was obtained in the same manner as in Example 1, except that the titanium nitride fine particles having an average particle diameter of 2.1 μm were replaced with titanium nitride fine particles having an average particle diameter of 0.7 μm. . Table 1 shows the results of evaluations performed in the same manner as in Example 1.

Comparative Example 1 Developer 6 was obtained in the same manner as in Example 1 except that the titanium nitride fine particles were not used. Table 1 shows the results of evaluations performed in the same manner as in Example 1.

Example 6 In Example 1, the titanium nitride fine particles had an average particle size of 1.2 μm.
A developer 7 was obtained in the same manner as in Example 1, except that the number of zirconia fine particles of m was changed. Table 1 shows the results of evaluations performed in the same manner as in Example 1.

Example 7 Styrene / butyl acrylate copolymer (copolymerization ratio 81/19, number average molecular weight (Mn) 8000, weight average molecular weight (Mw) 18000) 75 parts styrene / butyl acrylate copolymer (Copolymerization ratio 75/25, number average molecular weight (Mn) 40000, weight average molecular weight (Mw) 200,000) 25 parts ・ Magnetite 90 parts ・ Nigrosine dye 3 parts ・ Low molecular weight polypropylene 3 parts

The above materials were mixed and a black powder having a weight average diameter of 8.7 μm was obtained in the same manner as in Example 1. To 100 parts of this black powder, 0.5 part of titanium nitride fine particles having an average particle size of 2.1 μm and 0.6 part of hydrophobic silica fine powder treated with amino-modified silicone oil as a fluidizing agent are externally added by a Henschel mixer. Then, a developer 8 is used.

The developer is used as a copy machine NP202 manufactured by Canon.
0 was used in an electrophotographic apparatus modified into a transfer means using a transfer roller in contact with an electrostatic charge image carrier, at 25 ° C./5%
Images were continuously printed on 5000 sheets in a low humidity environment of Rh.

The developing conditions were as follows.

The closest gap between the photoconductor and the developing sleeve:
Approximately 300 μm ○ Closest gap between magnetic blade and developing sleeve: Approximately 23
0 μm ○ Thickness of developer on developing sleeve: 100 μm ○ Development bias: AC bias (Vpp1300V, frequency 1800Hz), DC bias (-230V)

The transfer conditions were as follows.

Surface rubber hardness of transfer roller: 24 ° Transfer current: 2.0 μA Transfer voltage: −2000 V Contact pressure: 40 g / cm (linear pressure) Conductive elastic layer of transfer roller: Conductive carbon Dispersed EPDM ○ Volume resistance of conductive elastic layer: 10 ⁸ Ω · cm

As a result, the image density is high even at the initial and durability 5000th sheets (initial 1.35th, 5000th sheet 1.
33), “Blank void in transfer” did not occur at all, and there was no fog, and a good image without scattering was obtained.

Further, after printing 5,000 sheets, the photoconductor was not scratched and a good halftone image was obtained.

Comparative Example 2 A developer 9 was obtained in the same manner as in Example 7, except that the titanium nitride fine particles in Example 7 were not used, and this was evaluated under the same conditions as in Example 7.

As a result, "dropout in transfer" occurred from the beginning,
Image density is also slightly low (initial 1.29, 5,000th sheet 1.
27), the fog and scattering were also inferior to those of Example 7.

Further, many scratches were generated on the photosensitive member, and the scratch marks were found on the halftone image.

[0087]

[Table 1]

[0088] According to the image forming method and an electrophotographic apparatus using an electrostatic charge image developer and the developer of the present invention, the developer is, i) contains a binder resin and a magnetic material, weight average
Magnetic toner particles Hitoshitsubu size Ru 7~10μm der, ii) 0.01 to 5 relative to 100 parts by weight of the magnetic toner particles.
Since it contains 0 part by weight of metal nitride fine particles having an average particle diameter of 0.5 to 5.0 μm and iii) silica fine powder, it has the following effects.

The electrostatic latent image formed on the surface of the electrostatic charge image bearing member is developed with a developer to form a developed image, and the surface of the electrostatic charge image bearing member is brought into contact with transfer means via a transfer material to develop the image. When an image is electrostatically transferred onto a transfer material to form an image, it is possible to obtain a high-quality image that is faithful to the electrostatic latent image.

The electrostatic latent image formed on the surface of the electrostatic image carrier is developed with a developer to form a developed image, and the surface of the electrostatic image carrier is brought into contact with a transfer means via a transfer material to develop the image. When an image is electrostatically transferred to a transfer material to form an image, does the phenomenon such as "dropout in transfer" or scratches on the electrostatic image carrier occur?
Alternatively, this phenomenon can be suppressed.

The electrostatic latent image formed on the surface of the electrostatic charge image carrier is developed with a developer to form a developed image, and a transfer means is brought into contact with the surface of the electrostatic charge image carrier through a transfer material to develop the image. When electrostatically transferring an image to a transfer material to form an image, even if various transfer materials such as thick transfer paper are used, phenomena such as "dropout in transfer" and scratches on the electrostatic image carrier will not occur, or This phenomenon can be suppressed.

[Brief description of drawings]

FIG. 1 is a good image with no voids during transfer.

FIG. 2 is a defective image in which voids occur during transfer.

FIG. 3 is a schematic view of a transfer unit having a transfer roller according to the present invention.

FIG. 4 is a schematic view showing a specific example of the electrophotographic apparatus of the present invention.

[Explanation of symbols]

101 electrostatic charge image carrier 102 charging means 103 transfer means 104 developing sleeve 105 electrostatic charge latent image forming means 106 erase exposure 107 Heat and pressure roller fixing device 108 Cleaning device 109 developing means 110 developer 111 Magnetic Doctor Blade 112 bias applying means 114 voltage applying means 115 Power Supply Unit of Charging Means P transfer material

Continued front page    (72) Inventor Takaaki Uetaki               3-30-2 Shimomaruko, Ota-ku, Tokyo               Within Canon Inc.                (56) Reference JP-A-4-113366 (JP, A)                 JP-A-2-2575 (JP, A)                 JP-A-4-204659 (JP, A)                 JP-A-60-179748 (JP, A)                 JP 62-17755 (JP, A)                 Japanese Patent Laid-Open No. 3-50562 (JP, A)                 Japanese Patent Laid-Open No. 1-177063 (JP, A)                 JP-A-3-59568 (JP, A)

Claims (3)

(57) [Claims] 1. The contact pressure between the electrostatic charge image carrier and the transfer means contacting via the transfer material in the transfer step is 20 g / c.
A developer used for an image forming method having a size of m or more, i) containing a binder resin and a magnetic material, and having a weight average particle size of 7
~10μm der Ru magnetic toner particles, ii) metal nitride particles and iii have an average particle size of 0.5 to 5.0μm 0.01 to 5.0 parts by weight per 100 parts by weight of the magnetic toner particles) A developer for developing an electrostatic charge image, which contains fine silica powder. 2. A step of forming an electrostatic latent image on the surface of an electrostatic image carrier, a step of developing the electrostatic latent image with a developer to form a developed image, and an electrostatic image having the developed image. A transfer means is applied to the surface of the carrier through a transfer material with a contact pressure of 20 g /
In the image forming method having a transfer step of electrostatically transferring the developed image onto a transfer material while abutting at a distance of cm or more, the developer contains i) a binder resin and a magnetic material, and has a weight average particle diameter.
Magnetic toner particles but Ru 7~10μm der, ii) magnetic toner particles 100 parts by weight of metal nitride fine particles and having an average particle size of 0.5 to 5.0μm 0.01 to 5.0 parts by weight with respect to iii) An image forming method characterized by containing fine silica powder. 3. An electrostatic charge image carrier, electrostatic charge latent image forming means for forming an electrostatic charge latent image on the surface of the electrostatic charge image carrier, and for developing the electrostatic charge latent image to form a developed image. Developing means for holding the developer, and 20 g of the electrostatic charge image carrier for electrostatically transferring the developed image to the transfer material via the transfer material.
In the electrophotographic apparatus having a transfer unit provided so as to be contactable with a contact pressure of / cm or more, the developer held in the developing unit contains i) a binder resin and a magnetic material , 0 weight average particle diameter of 7~10μm der Ru magnetic toner particles, ii) with respect to 100 parts by weight of the magnetic toner particles.
An electrophotographic apparatus comprising 01 to 5.0 parts by weight of metal nitride fine particles having an average particle diameter of 0.5 to 5.0 μm and iii) silica fine powder.