JPH04143767A - Electrostatic charge image developing developer and image forming device - Google Patents

Abstract

PURPOSE:To obviate the generation of toner fusion on a photosensitive body and to suppress the toner fusion by incorporating negatively charged resin particles having 0.03 to 1.0mum average grain size and 10<3> to 10<12>OMEGA.cm specific electric resistance into the above developer. CONSTITUTION:This developer contains the negatively charged spherica resin particles having 0.03 to 1.0mum average grain size and 10<3> to 10<12>OMEGA.cm specific electric resistance and substantially prevents the fusion of the toners to the surface of the photosensitive body. Namely, one of the causes that the toners fuse to the surface of the photosensitive body includes the flaws generated when the surface of the photosensitive body is rubbed by the inorg. particles and contact member. The fusion of the toners to the photosensitive body is effectively prevented by removing the free inorg. particles in order to prevent the generation of such flaws on the surface of the photosensitive body. The negatively charged resin particles have the effect of adsorbing the free inorg. particles onto the surface. This effect is evident when observed by a scanning type electron microscope. The good copied images are obtd. without allowing the fusion of the toners to the photosensitive body even when copying is continued over a long period of time.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a developer, an image forming apparatus, and an image forming apparatus for visualizing electrostatic images in image forming methods such as electrophotography, electrostatic recording, and electrostatic printing. Regarding methods etc.

More specifically, the present invention relates to a developer, an image forming apparatus, an image forming method, etc. used in electrophotography, which includes a charging step in which a charging member to which a voltage is externally applied is brought into contact with a member to be charged.

[Background technology]

Conventionally, a corona discharger is known as a charging means in an electrophotographic apparatus. Corona dischargers have the problems of having to apply high voltage (and generating a large amount of ozone).

Nearby, consideration is being given to using contact charging means without using a corona discharger. Specifically, while applying a voltage to a conductive roller that is a charging member, the roller is brought into contact with an object to be charged, such as a photoreceptor, and the surface of the object to be charged is charged to a predetermined potential. If such contact charging means is used, the voltage can be lowered compared to a corona discharger, and the amount of ozone generated can also be reduced.

For example, in Japanese Patent Publication No. 50-13661, it is possible to charge photosensitive paper by applying a low voltage by using a roller whose core metal is coated with a dielectric material made of nylon or polyurethane comb.

However, in the conventional example described above, the roller whose core metal is coated with nylon does not have the elasticity of rubber, so it cannot maintain sufficient contact with the object to be charged, and tends to cause charging failure. On the other hand, when the core metal is coated with polyurethane rubber, the softening agent impregnated in the comb gradually seeps out. Therefore, when a photoreceptor is used as a charged object,
There is a problem in that when the photoreceptor is stopped, the charging member sticks to the photoreceptor at the contact portion, or the image blurs in the area of the contact portion. If the softening agent in the rubber material of the charging member seeps out and adheres to the surface of the photoreceptor, the resistance of the photoreceptor decreases, causing image deletion, and in severe cases, it may become unusable or the toner remaining on the surface of the photoreceptor may become charged. It may also adhere to the surface of the member and cause a filming phenomenon. When a large amount of toner adheres to the surface of the charging member, the surface of the charging member becomes insulated, the charging ability of the charging member is lost, and the surface of the photoreceptor becomes non-uniformly charged, which affects the toner image. This is because the residual toner is more strongly pressed against the surface of the photoreceptor by the charging member, which makes it easier for the residual toner to stick to the charging member or the surface of the charged object and to damage or scrape the surface of the photoreceptor.

In a contact charging device, a DC voltage or a DC voltage superimposed with an AC voltage is applied to the charging member. At this time, in the vicinity of the contact portion between the charging member and the photosensitive drum, abnormal charging and flying motion of the residual toner particles, which are small in particle size and light in weight, are repeated. For this reason, residual toner is likely to be electrostatically attracted to or embedded in the surface of the charging member or the photosensitive drum, and contact charging means is very different from conventional non-contact charging means using a corona discharger.

On the other hand, in recent years, small and inexpensive personal use copying machines and racer printers have appeared. In these small machines, from the viewpoint of maintenance-free operation, it is preferable to use a cartridge system in which components such as a photoreceptor, a developing device, and a cleaning device are integrated. Furthermore, it is preferable to use a one-component dry type magnetic developer since the structure of the developing device can be easily constructed.

Methods using magnetic toner include, for example, the magnetry method using conductive toner described in U.S. Pat. Transfer method, JP-A-54-42] No. 41, JP-A-55-18656
There is a method of developing a latent image by causing toner particles to fly against it, as disclosed in Japanese Patent Application No.

In a method using such a dry magnetic developer, in order to form a visible image of good quality, the developer needs to have high fluidity and uniform chargeability. Conventionally, fine silicic acid powder has been added and mixed to toner powder. Fine silicic acid powder (i.e., phosphoric acid) itself is hydrophilic, and therefore, developers to which it is added may aggregate due to moisture in the air, resulting in decreased fluidity, or in extreme cases, the fine silicic acid powder may deteriorate. Moisture absorption reduces the charging performance of the developer.

Therefore, the use of hydrophobized silicic acid fine powder has been proposed in JP-A-46-5782, JP-A-48-47345, and JP-A-48-47346. Specifically, for example, fine silicic acid powder is made hydrophobic by reacting fine silicic acid powder with an organosilicon compound such as dimethylcyclosilane to replace the 7-ranol groups on the surface of the fine silicic acid powder with an organic group. ing.

The magnetic toner itself has a polishing effect. In an image forming process in which a photoconductor with a low surface hardness such as an organic photoconductor (OPC) is pressed against a photoconductor, especially when a developer containing a mixture of magnetic toner and inorganic fine powder is used, the pressure contact member and the surface of the photoconductor may be damaged. Scraping of both surfaces tends to cause white spots, damage to the pressure contact member and the photoreceptor, and contamination of the photoreceptor such as toner fusion and filming.

JP-A-60-186854 and others propose adding polymer particles smaller than toner particles.

When a developer was prepared in a similar manner and examined, it was found to have no effect on toner fusion on the photoreceptor, and in devices using contact charging, it tended to contaminate the contact charging device and cause charging unevenness.

As the performance of host computers has improved in recent years, there has been a demand for racer hem printers with fast printing speeds. From the standpoint of the office environment, there is a long-awaited desire for an image forming apparatus that does not generate osone.

Generally, in contact charging, as the process speed increases, it is necessary to increase the applied voltage and AC frequency in order to stabilize the charging on the photoreceptor. At the same time, there is a problem in that the developer is more likely to fuse to the photoreceptor.

In recent years, requirements for image quality have become increasingly strict, and it is now necessary to faithfully reproduce even the finest latent images without distortion or interruption.

Along with this, the particle size of toner is also becoming smaller.

For example, JP-A-1-112253 proposes a developer having a volume average particle diameter of 4 to 9 μm.

In general, the smaller the particle size of the toner, the larger the specific surface area of the toner, so when such toner is used, it is more likely to cause contamination of the contact member and photoreceptor, and furthermore, the cohesiveness of the toner increases, resulting in poor fluidity. In order to ensure this, it is necessary to add more inorganic fine powder, and as a result, white spots occur due to scraping of the surface of the pressure contact member and photoreceptor, toner fusion occurs due to scratches on the pressure contact member and photoreceptor, and
This tends to encourage filming and the like, resulting in image defects.

[Purpose of the invention]

The purpose of the present invention is to prevent toner fusion from occurring on the photoreceptor;
Another object of the present invention is to provide a developer for developing electrostatic images in which toner fusion is suppressed.

An object of the present invention is to provide a developer and an image forming apparatus that can produce toner images with high density and no fog.

An object of the present invention is to provide a developer that is less likely to contaminate a contact charging device.

An object of the present invention is to provide an image forming apparatus that is less likely to cause uneven charging of a photoreceptor by a contact charging device.

An object of the present invention is to provide a developer that can stably supply a sharp, high-density visible image that is faithful to the latent image.

An object of the present invention is to provide an image forming apparatus having at least a contact charging means and a developing means for developing with the developer of the present invention.

[Summary of the invention]

That is, the present invention uses a toner and an average particle size of 0.0.
3 to 1.0 μm and specific electrical resistance of 106 to 10"
The present invention relates to a developer for developing electrostatic images characterized by containing negatively chargeable resin fine particles having a diameter of Ω·cm.

Further, the present invention provides a contact charging means for charging a photoreceptor while contacting it for carrying an electrostatic charge image, and a toner having an average particle size of 0.03 to 1.0 μm and a volume electric resistance of 10.
An image forming apparatus comprising a developing means for developing an electrostatic image formed on a photoreceptor with an electrostatic image developing developer containing negatively charged spherical resin fine particles of 6 to 1012 Ω·cm. Regarding.

Further, the present invention provides a photoreceptor, a contact charging means, a toner, an average particle size of 0.03 to 1.0 μm, and a volume electric resistance of 1.
A developing means for developing an electrostatic image formed on a photoreceptor with a developer for developing an electrostatic image containing negatively charged spherical resin particles of 06 to 1012 Ω·cm, the contact charging means and the developing device. The present invention relates to an apparatus unit characterized in that the means integrally supports the photoreceptor to form a unit, and forms a single unit that can be freely attached to and detached from the apparatus main body.

Furthermore, the present invention includes an electrophotographic apparatus and a receiving means for receiving image information from a remote terminal, and the electrophotographic apparatus includes a contact for charging a photoreceptor while contacting the photoreceptor for carrying an electrostatic image. A charging means, a toner and an average particle size of 0.
03~1.0μm and volume electrical resistance 106~1012Ω
- A facsimile machine characterized by being an image forming apparatus having a developing means for developing an electrostatic image formed on a photoreceptor with an electrostatic image developing developer containing negatively charged spherical resin particles of Cm. Regarding equipment.

[Detailed description of the invention]

The developer of the present invention contains negatively charged spherical resin particles with an average particle size of 0.03 to 1 μm and a volumetric electrical resistance of 106 to 10'2 Ω·cm. is fused.

The reason why the negatively charged resin particles are effective in preventing toner from adhering to the photoreceptor is considered to be as follows.

One of the causes of toner being fused to the surface of a photoreceptor is scratches that occur when the surface of the photoreceptor is rubbed by inorganic fine particles and a contact member. In order to prevent the occurrence of scratches on the surface of the photoreceptor, removal of free inorganic fine powder is effective in preventing photoreceptor fusion. The negatively charged resin particles of the present invention have a function of adsorbing this free inorganic fine powder to the surface, and this function is clear when observed with a scanning electron microscope.

In an image forming apparatus equipped with a contact charging device,
It is thought that the negatively charged resin particles that have slipped through the cleaning blade are adsorbed by the contact charging means, and the free inorganic fine powder that has slipped through the cleaning plate is further adsorbed onto the surface, thereby protecting the surface of the photoreceptor.

The negatively charged resin fine particles used in the present invention have a primary average particle size of 0.03 to 1.0 μm, preferably 0.05 to 0.8 μm.
A micrometer one is used. If the particle size is larger than 1.0 μm, the specific surface area is small, and it is not suitable for adsorbing free inorganic fine powder (for example, silica), and the effect of preventing toner fusion is small. If the average particle size is less than 0.03 μm, cleaning defects are likely to occur.

The negatively charged spherical resin fine particles have a specific electrical resistance of 106 to 1.
012 Ω·cm is used. If a resistor with a resistance lower than 106 Ω·cm is used, the amount of charge of the developer will be decreased, resulting in a decrease in image density. If the resistance is higher than 1012 Ω·cm, the fluidity of the developer will deteriorate, resulting in images with a lot of fog.

The negatively charged spherical fine particles have a triboelectric charge of 150 μc/g.
~-400μc/g (more preferably -50μc/g
-300 μc/g) is preferable.

If the triboelectric charge amount of the negatively charged resin particles is less than 150 μC/g, the effect of preventing photoreceptor fusion is small and image density tends to decrease, while if it is more than −400 μC/g, fluidity deteriorates.

The amount of tribocharge of the negatively charged spherical resin particles used in the present invention is measured as follows.

0.2 g of fine resin particles left overnight in an environment with a temperature of 25°C and a humidity of 50 to 60% RH and carrier iron powder not coated with resin (for example, Nippon Steel) with a main particle size of 200 to 300 mesh. Kousha EFV200/300)9
9.8 g in an aluminum pot with a volume of approximately 200 cc under the above environment, mixed for 60 minutes, and then heated to a blowing pressure of 0.5 kg/c+rf using an aluminum cell with a 400 mesh screen. hand,
The triboelectric charge amount of the resin particles is measured by the blow-off method.

For measurement of number average particle diameter, Coulter Counter N4 (Nikikaki tM) (measurement range o, oos ~ 3 μm)
Measurement is performed in a state in which the substance is dispersed in a solvent using ultrasonic waves.

It may be measured using CAPA-5000 model (manufactured by Horiba Seisakusho). Practically monodispersed materials obtained by emulsion polymerization etc. have a magnification of 7,500 to 50,000 times (preferably 7,500 times).
Scanning micrograph (SEM
The number average particle diameter may be measured by randomly extracting 20 to 50 spherical particles from the photograph.

The electrical resistivity (volume resistivity) in the present invention is measured using, for example, the apparatus shown in FIG. 4 at a temperature of 23.5°C.
The test is carried out in an environment with a humidity of 65% RH. In the figure, reference numeral 41 indicates a pedestal, and reference numeral 42 indicates a pressing means, which is connected to a hand press and has a pressure gauge 43 attached thereto. 44 has a diameter of 3.1
Sample 45 is placed in a 00 cm hard glass cell.

46 is a brass press ram with a diameter of 4.266 cm and an area of 14.2857 cr&o 47 is a stainless steel push rod with a radius of 0.397 cm and an area of 0.496 crd, which applies pressure from the press ram 46 to the sample 45. 48 is a brass base, 49 and 50 are Bakelite insulation plates. 51
is a resistance meter connected to the press ram 46 and the stand 48, and 52 is a dial gauge.

In the device shown in Figure 4, the hand press has a hydraulic pressure of 20 kg/
When a pressure of crrf is applied, the sample has a pressure of 576 kg/c+
A pressure of d is applied. The applied voltage is IOV, and the resistance meter 51
The resistance is read from , multiplied by the cross-sectional area of the sample, and divided by the height of the sample read from the dial cane 52 to determine the volume resistivity.

The negatively charged spherical resin fine particles used in the present invention are preferably spherical, and specifically, the resin fine particles have a ratio of the short axis to the long axis (major axis/breadth axis) of 1.0 to 1.02. is excellent in preventing photoreceptor fusion.

The resin fine particles are produced by an emulsion polymerization method, a spray drying method, or the like.

Preferably, the glass transition point obtained by copolymerizing monomer components used in toner binder resins such as styrene, acrylic acid, methyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate by an emulsion polymerization method. resin particles show good effects.

In the present invention, the resin particle surface may be crosslinked with a crosslinking agent such as divinylbenzene, and the surface of the resin particle may be treated with a metal, metal oxide, pigment, surfactant, etc. in order to adjust the specific electrical resistance and tribocharge amount. is a preferred form.

The toner contained in the developer of the present invention has a volume average particle size of 3
It is preferable to have a diameter of ~20 μm (preferably 4 to 15 μm).

When the toner contained in the developer of the present invention is a magnetic toner, it is preferable that the volume average particle diameter of the magnetic toner be 4 to 8 (preferably 6 to 8) μm to improve the resolution and fog suppression of the developer. It's very good. Furthermore, in the case of a developer containing magnetic toner, the BET specific surface area is 18 to 3. sn(/g
It is further preferable that the loose apparent density be 04 to 0.52 g/cm and the true density be 45 to 1.8 g/cm from the viewpoint of developer resolution and fog suppression.

The BET specific surface area of the developer of the present invention determined by the nitrogen gas adsorption method is preferably 1.8 to 3.5 rd/g; within this range, the developer of the present invention has a quick rise, good developer efficiency, and a high surface area on the photoreceptor. It is also highly effective in preventing toner adhesion to.

It is preferable that the true specific gravity of the developer of the present invention is 1.45 to 1.8, and within this range, the developer of the present invention can be applied in an appropriate amount to the latent image during development. On the other hand, a faithful high-density image can be obtained without becoming thick or thin. If the true specific gravity is less than 45, the inside of the apparatus will be contaminated due to developer scattering, and toner fusion on the photoreceptor will likely occur due to increased fog.

The loose apparent density of the developer of the present invention is 04 to 052 (g/
cm3), and is characterized by a small loose apparent density compared to the true specific gravity. The porosity calculated from true specific gravity and loose apparent density is preferably 62 to 75%.

The porosity (εa) is calculated by the following formula.

The solidified apparent density of the magnetic toner is preferably in the range of 0.8 to 1.0, and the porosity (ε,) in this case is preferably 40 to 50%.

Within this range, the developer of the present invention does not cause developer clogging inside the developing device and replenishes the developer to the developing section smoothly, so that it always maintains a stable density without causing white spots. Furthermore, it is possible to prevent the toner from leaking or scattering, and even after many printing tests, the toner does not change in quality, and the toner is prevented from fusing onto the photoreceptor.

The BET specific surface area of magnetic toner is QUANTACHROM
Specific surface area meter manufactured by E Company Specific surface area meter manufactured by Autoso Company Determined by the Autosorb method.

The loose apparent density in the present invention was measured using a fine-circle micron powder tester and a container attached to the powder tester according to the procedure in the instruction manual of the powder tester.

In the measurement of true density in the present invention, when measuring fine powder,
The following method was adopted as an accurate and simple method.

A cylinder made of stainless steel with an inner diameter of 10 mm and a length of about 5 cm, and an outer diameter of about 10 m that can be inserted tightly into it.
m.

A disk (A) with a height of 5 mm and an outer diameter of about 10 mm.
, prepare a piston (B) with a length of about 8 cm. Place the disk (A) at the bottom of the cylinder, then add approximately 1 g of the sample to be measured.
and gently push in the piston (B). A force of 400 kg/crrr was applied to this using a hydraulic press, and the product was compressed for 5 minutes and taken out. The diameter (Dcm) and height (L cm ) of the compressed sample are measured by weighing (wg) L/micrometer, and the true density is calculated using the following formula.

In the magnetic toner according to the present invention, the volume average particle diameter is 4
~8 (preferably 6-8) μm, preferably 5 μm
17 to 60% by number of magnetic toner particles having a particle size of not more than m is contained, and 5 to 50% by number of magnetic toner particles having a particle size of 6.35 to 10.081 tm are contained; 12.
Magnetic toner particles having a particle size of 7 μm or more are contained at 2.0% by volume or less, and magnetic toner particles having a particle size of 5 μm or less are contained in the following formula % [where N is magnetic toner particles having a particle size of 5 μm or less]. (2) represents the volume % of magnetic toner particles having a particle size of 5 μm or less, and k represents a positive number from 4.6 to 6.7. However, N represents a positive number from 17 to 60. ] It is preferable that the LX0 magnetic toner has a particle size distribution that satisfies the following. If the volume average particle diameter of the LX0 magnetic toner is less than 4 μm, the amount of toner applied on the transfer paper will be small (the image density will be low) in applications with a high image area ratio such as graphic images. (This is easy to happen.
This is thought to be due to the same reason as the reason why the density inside the edge portion of the latent image decreases, which will be described later. moreover,
If the volume average particle diameter of the magnetic toner is less than 4 μm, toner fusion tends to occur on the photoreceptor.

When the volume average particle size of the magnetic toner exceeds 8 μm,
The resolution is not good and the image quality tends to deteriorate due to durability. When the number of magnetic toner particles with a particle size of 5 μm or less is less than 17% by number, there are few magnetic toner particles effective for high image quality.
In particular, as the toner is used by continuing to print out, the effective magnetic toner particle component decreases, the variation in particle size distribution of the magnetic toner as shown in the present invention worsens, and the image quality gradually deteriorates. . 60 pieces%
If the magnetic toner particles exceed the above range, aggregation of magnetic toner particles tends to occur, resulting in toner lumps larger than the original particle size, resulting in rough image quality, lowering resolution, and increasing the density between the edges and the inside of the latent image. The difference becomes thick (the image tends to be hollow), and toner fusion on the photoreceptor tends to occur.

It is preferable that the number of particles in the range of 6.35 to 10.08 μm is 5 to 50% by number or less, and preferably 8 to 40% by number. When the number is more than 50%, the image quality deteriorates and
There is a tendency for more development than necessary (that is, too much toner is applied), resulting in a decrease in fine line reproducibility and an increase in toner consumption. On the other hand, if it is less than 5% by number, it becomes difficult to obtain high image density. N/V
=-0,05N+, and 4.6≦≦6.
Indicates a positive number in the range of 7. Preferably 4.6≦≦6.2
, more preferably 4.6≦ and ≦5.7. As indicated above, 17≦N≦60, preferably 25≦N≦6
0, more preferably 30≦N≦60.

1 (< 4.6, the number of magnetic toner particles with a particle size smaller than 5.0 μm is small, resulting in poor image density, resolution, and sharpness. The presence of an appropriate amount of magnetic toner particles contributes to the close packing of toner during development and the formation of a uniform image without roughness.Especially by uniformly filling in fine lines and image contours. , which further enhances visual sharpness.K of 4.6 is inferior in these characteristics due to the lack of this particle size distribution component.

From another point of view, in terms of production, it is necessary to cut a large amount of fine powder by classification or the like in order to satisfy the condition of k<4.6, which is disadvantageous in terms of yield and toner cost.

k〉67, due to the presence of more fine powder than necessary (the image density tends to decrease as printouts are continued).Such a phenomenon is caused by excessive fine powder magnetism with more charge than necessary It is thought that this occurs when toner particles are charged and adhered to the developing sleeve, preventing normal magnetic toner from being carried on the developing sleeve and being charged.Furthermore, when k > 6.7, toner fusion on the photoconductor occurs. Easy to occur.

2. Magnetic toner particles with a particle size of 12.7 μm or more. It is preferably at most Q volume %, more preferably at most 1.0 volume %, even more preferably at most 0.5 volume %. If it is more than 20% by volume, it tends to interfere with fine line reproduction.

The particle size distribution of toner can be measured by various methods.
In the present invention, a Coulter counter was used.

A Coulter Counter TA-n type (Coulter Co., Ltd.!M) was used as the measuring device, and an interface (manufactured by Nikkaki) that outputs the number distribution and volume distribution and a CX-1 burner computer (manufactured by Canon) were connected. As the electrolytic solution, an approximately 1% NaCl aqueous solution is prepared using primary sodium chloride. The measurement method is as follows: 100 to 150 m of the electrolytic aqueous solution
1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, as a dispersant, and further 2 to 20 mg of the sample to be measured. The electrolytic solution in which the sample was suspended is dispersed for about 1 to 3 minutes using an ultrasonic disperser, and then used as an aperture using the Coulter Counter TA-n type. Using a 00μ aperture, 2
The particle size distribution of particles of ~40μ is measured and the value according to the invention is determined therefrom.

The toner contained in the developer of the present invention usually consists of a binder resin and a magnetic material or a colorant.
).

As the binder resin of the toner according to the present invention, monopolymers of styrene and its substituted products such as polystyrene and polyvinyltoluene, styrene-propylene copolymers, styrene-propylene copolymers, and
Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, Styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer , styrenic copolymers such as styrene maleate copolymers, polymethyl methacrylate, polybutyl methacrylate,
Polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, paraffin wax, carnauba wax, etc. Can be mentioned. These can be used alone or in combination.

Pigments or dyes can be used as colorants that can be added to the toner according to the invention. For example, conventionally known carbon black, copper phthalocyanine, etc. can be used.

As the magnetic fine particles contained in the magnetic toner according to the present invention, a substance that is magnetized when placed in a magnetic field is used.

For example, powders of ferromagnetic metals such as iron, cobalt, and nickel; or alloys and compounds such as iron-based alloys, nickel-based alloys, magnetite, γ-Fe 203 , and ferrite can be used.

These magnetic fine particles preferably have a BET specific surface area of 1 to 20 d/g, especially 2.5 to 12 by nitrogen adsorption method.
fI? /g and a Mohs hardness of 5 to 7 is preferred. The content of this magnetic powder is preferably 10 to 70% by weight based on the weight of the toner.

The toner according to the present invention preferably has negative chargeability, and may contain a charge control agent if necessary. Further, the magnetic toner according to the present invention has a volume resistivity of 101° Ω·cm or more, particularly 10 12 Ω·c.
m or more (preferable from the viewpoint of strong triboelectric charge and electrostatic transferability). The volume resistivity referred to here means that the toner is loO
It is defined as the value calculated from the current value after 1 minute has elapsed after molding with a pressure of kg/crrf and applying an electric field of 100 V/cm to this.

The binder resin of the toner contained in the developer of the present invention contains 3 to 20 parts by weight of a polymerizable monomer unit having an acid group consisting of a carboxyl group or its acid anhydride in 100 parts by weight of the binder resin. It is particularly preferable to use a binder resin having an acid value of 1 to 70.

Various resins can be used as the binder resin having an acid group, but the molecular weight distribution of the tetrahydrofuran (THF) soluble portion determined by Köl permeation chromatography (GPC) is based on the weight average molecular weight/number average molecular weight (M w
/Mn)≧5, and the molecular weight is from 2,000 to less than 15,000 (preferably from 2,000 to 10,000).
0) and has a molecular weight of 15,000 to 1
A resin having a peak or shoulder in the 00,000 region is preferred. This is mainly due to the THF-insoluble content, which has anti-offset properties.
THF-soluble components with a molecular weight of less than 15,000, particularly 10,000 or less, mainly affect blocking properties, adhesion to photoreceptors, and filming properties, and THF Molecular weight of soluble component: 10.000
This is based on the fact that the components above 15,000 in particular mainly affect the fixing performance.

A copolymer containing an acid group consisting of a carboxyl group or its acid anhydride group may be included in both molecular weight distribution regions of any given L%11.In the present invention, GPC
The molecular weight of the peak and/or shoulder of the chromatogram (gel permeation chromatography) is measured under the following conditions.

The column was stabilized in a heat chamber at 40°C, and tetrahydrofuran was added as a solvent to the column at this temperature at 1 mj/min! The sample concentration was 0.05.
A THF sample solution of resin adjusted to ~066% by weight was added to 50%
Inject ~200 μl and measure. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithm value and the count number of a calibration curve prepared from several types of monodisperse polystyrene standard sample numbers. As a standard polystyrene sample for creating a calibration curve, for example, P r e s
S ur e Ch e m i c a IC
o, or manufactured by Toyo Tsudani Gyo Co., Ltd., with a molecular weight of 6X102゜2, 1X10", 4X10", 1.75X10', 5.
lX1O'.

1, lX10', 3.9X10', 8.6X10', 2
X10'.

It is appropriate to use a polystyrene sample measuring 4.48 x 10' and at least 10 standard polystyrene samples.

An R1 (refractive index) detector is used as a detector.

As a column, in order to accurately measure the molecular weight range of 103 to 4 x 10', it is recommended to combine a plurality of commercially available polystyrene gel columns.
p-styragel 500.10", 10
4.105 combination and 5hodex manufactured by Showa Denko
KF-80M, KF-802, 803, 804, 8
05 combination or TSKgel manufactured by Toyo Soda
G100OH, G2000H.

G2500H, G3000HXG4000H, G500
0H, G6000H.

A combination of G700OH and GMH is preferred. .

The weight percent of the binder resin of the present invention having a molecular weight of 10,000 or less is the molecular weight of 10 in the chromatogram determined by GPC.
,000 or less, and calculate the weight ratio with the cutouts having a molecular weight of 10,000 or more, and calculate the weight % with respect to the entire binder resin.

Examples of the polymerizable monomer having an acid group that can be used in the present invention include the following.

α, β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid; α, β-unsaturated carboxylic acids such as maleic acid, butyl maleate, octyl maleate, fumaric acid, and butyl fumarate;
Unsaturated nocarboxylic acids or half esters thereof: n-
Examples include alkenylcarphonic acids such as butenylsuccinic acid, n-offtail succinic acid, butyl n-butenylsuccinate, n-butenylmalonic acid, n-butenylsuccinic acid, and half esters thereof.

In this case, the amount of the polymerizable monomer containing acid groups is preferably 3 to 30 parts by weight based on the total amount of the binder resin, and the acid value of the entire binder resin is preferably 1 to 70, more preferably 5 to 50. .

The method for measuring acid value used in the present invention is shown below.

The acid value is measured according to JIS K-0670.

Sample 2~log 200~300mj! into an Erlenmeyer flask, and add about 50 mA of a mixed solvent of ethanol and benzene = 1.2 to dissolve the resin. If the solubility is poor, a small amount of acetone may be added. Pre-standardized N/1 using phenolphthalein indicator
Titrate from 0-potassium to ethanol solution, calculate the acid value (m g K
OH/g).

Acid value = KOH (number of rrl) x N x 56.1/sample weight・
(3) (N is a factor of N/10 KOH) Examples of comonomers for obtaining the binder resin having acid groups according to the present invention include the following.

For example, styrene: 0-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p
-Phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-
Butylstyrene, pn-hexylstyrene, pn-
Styrene derivatives such as octyl styrene, p-n nonylstyrene, p-n-decylstyrene, and p-n dodecylstyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; unsaturated polyenes such as butadiene; vinyl chloride, vinylidene chloride, vinyl bromide, vinyl chloride such as concentrated vinyl,
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate: methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-methacrylate
α-methylene aliphatic compounds such as butyl, isobutyl methacrylate, n-octyl methacrylate, dodenyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and ethylaminoethyl methacrylate. Monocarboxylic acid esters; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate,
Dodecyl acrylate, 2-ethylhexyl acrylate,
stearyl acrylate, 2-chloroethyl acrylate,
Acrylic acid esters such as phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hequinole ketone, and methyl isopropenyl ketone; N-vinylpyrrole, N
- N-vinyl compounds such as vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone Vinylnaphthalenes: Examples include acrylic acid derivatives or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

These vinyl monomers may be used alone or in combination with the acid group-containing monomers described above.

Among these, combinations of monomers that result in styrene copolymers and styrene-acrylic copolymers are preferred.

As the crosslinking monomer, monomers having two or more polymerizable double bonds are mainly used.

The vinyl copolymer used in the present invention is preferably a polymer crosslinked with a crosslinkable monomer as exemplified below.

Aromatic divinyl compounds (e.g. divinylbenzene, divinylnaphthalene); diacrylate compounds linked with alkyl chains (e.g. ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1
．． 4-butanediol diacrylate, 1.5-bentanediol diacrylate, 1.6-hexanediol diacrylate, neopentyl glycol diacrylate, and the above compounds in which the acrylate is replaced with methacrylate); alkyl containing an ether bond Chained diacrylate compounds (e.g. diethylene glycol cyacrylate-L/-), diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol #400 diacrylate,
polyethylene glycol #600 diacrylate, dipropylene glycol diacrylate, and the above compounds in which the acrylate is replaced with methacrylate); chain-linked diacrylate compounds containing aromatic groups and ether bonds [e.g., polyoxyethylene (2)-2,
2-bis(4-hydroxyphenyl)propane diacrylate, polyoxyethylene(4)-2,2-bis(4
-hydroxyphenyl)propane diacrylate, and those in which the acrylate of the above compound is replaced with methacrylate]; and furthermore, polyester type diacrylate compounds [for example, trade name MANDA (Nippon Kayaku)].

Examples of polyfunctional crosslinking agents include pentaerythritol triacrylate, trimethylolethane triacrylate,
Examples include trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and nitriallyl cyanurate and triallyl trimellitate obtained by replacing the acrylate of the above compounds with methacrylate.

These crosslinking agents are used in an amount of 0.00 parts by weight based on 100 parts by weight of other monomer components. It is preferable to use about 1 to 5 parts by weight (more preferably about 0.03 to 3 parts by weight) of O.

Among these crosslinking monomers, aromatic divinyl compounds (particularly divinylbenzene),
Mention may be made of chain diacrylate compounds containing aromatic groups and ether linkages.

The method for synthesizing the binder resin according to the present invention basically consists of two steps.
A method of synthesizing more than one type of polymer or copolymer is preferred.

This is a method in which a first polymer or copolymer that is soluble in THF and soluble in a polymerization monomer is dissolved in a polymerization monomer, and the monomers are polymerized to obtain a resin composition.

In this case, a composition is formed in which the former and latter polymers or copolymers are uniformly mixed.

The first polymer or copolymer soluble in THF is preferably subjected to solution polymerization or ionic polymerization, and the second polymer or copolymer for producing a THF-insoluble component is preferably polymerized by solution polymerization or ionic polymerization. It is preferable to synthesize the polymer or copolymer by suspension polymerization or bulk polymerization in the presence of a crosslinking monomer under conditions in which the polymer or copolymer of No. 1 is dissolved. The first polymer or copolymer is used in an amount of 10-120 (preferably 2
It is preferable to use 0 to 100 parts by weight.

Solvents used in solution polymerization include xylene, toluene,
Cumene, acid cellosolve, isopropyl alcohol, benzene, etc. are used. In the case of styrene monomers, xylene, toluene or cumene are preferred. It is appropriately selected depending on the polymer to be polymerized. In addition, the initiator is
ert-butyl peroxide, tert-butyl peroxybenzoate, benzoyl peroxide, 2.2
'-azobisisobutyronitrile, 2,2'-azobis(2,4 dimethylvaleronitrile), etc. are monomers of 100%
0.1 parts by weight or more (preferably 0.4 to 0.4 parts by weight)
15 parts by weight). The reaction temperature is
Although it varies depending on the solvent, initiator, and polymer to be polymerized, it is preferable to carry out the reaction at a temperature of 70°C to 180°C. In solution polymerization, it is preferable to use 30 to 400 parts by weight of monomer per 100 parts by weight of solvent.

The developer of the present invention preferably contains a hydrophobic inorganic fine powder as an additive. The hydrophobic inorganic fine powder is preferably a hydrophobic metal oxide fine powder, and hydrophobic silicic acid (
It is more preferable that the silica is a fine powder.

Among the above-mentioned inorganic fine powders, those having a BET specific surface area due to nitrogen adsorption measured by the BET method within the range of 70 to 300 rrr/g give good results. The hydrophobic silica fine powder is preferably used in an amount of 0.1 to 3.0 parts by weight, preferably 0.2 to 2.0 parts by weight, per 100 parts by weight of toner.

As the hydrophobic silica fine powder, negatively charged hydrophobic silica fine powder is preferable.

The hydrophobic silica fine powder used in the present invention has a tribocharge amount of -
Those having I00 μC/g to −300 μC/g are preferably used. If the amount of triboelectric charge is less than 1,100 μc/g, the amount of tribocharge of the developer itself tends to decrease, and the humidity characteristics tend to deteriorate.

If it exceeds 300 .mu.c/g, the memory of the developer carrier will be promoted, the developer will be more susceptible to silica deterioration, etc., and its durability will tend to be impaired.

If the BET specific surface area is finer than 300 rrr/g, the effect of adding it to the developer will be small, and 70 IT? /g, the probability of existence of coarse particles as free substances is high, and this tends to cause uneven distribution of silica and the occurrence of black spots due to silica aggregates.

The tribo value of negatively charged silica fine powder is measured by the following method. 0.2 g of fine silica powder left overnight in an environment of 23.5°C and 60% RH and carrier iron powder (e.g., Japanese iron powder) that is not coated with resin and has a main particle size of 200 to 300 mm. EFV200/300)
9.8g under the above environment, approximately 50c, c,
Mix thoroughly (hold in hand and shake up and down approximately 50 times for approximately 20 seconds) in a wide-mouth polyethylene bottle with a lid having a volume of . Next, as shown in FIG. 3, approximately 0.5 g of the mixture is placed in a metal measuring container 32 with a 400-mesh screen 33 at the bottom and a metal lid 34 is placed. The weight of the entire measuring container 32 at this time is measured as W+(g). Next, in the suction device 31 (at least the part in contact with the measurement container 32 is an insulator), suction is performed from the suction port 37 and the air volume control valve 3
6 to adjust the pressure of the vacuum gauge 35 to 250 mm Hg.
shall be. In this state, suction is applied sufficiently to remove the silica. The potential of the electrometer 39 at this time is assumed to be V (volt). Here, 38 is a capacitor, and the capacitance is C (μF).

The weight of the entire measurement container after suction is weighed and is defined as W2 (g).

The amount of triboelectric charge (μc/g) of this silica is calculated as shown in the following formula.

The silicic acid fine powder used in the present invention is dry silica (
Alternatively, both fumed silica) and wet silica made from water glass or the like can be used. There are few silanol groups on the surface and inside the silicic acid fine powder, and Na
20. Dry silica without residues such as So 3''- is preferable to wet silica.

For dry silica, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halide compounds such as aluminum chloride or titanium chloride together with silicon halide compounds in the manufacturing process. These are also included.

The average primary particle size of the particles is preferably within the range of 0.001 to 2μ, particularly preferably 0.02μ.
It is preferable to use silica fine powder within the range of ~0.2μ.

For the degree of hydrophobicity of the inorganic fine powder in the present invention, a value measured by the following method is used. Other measurement methods can also be applied while referring to the measurement method of the present invention.

200 mj of sealed type! Add 10 ml of ion-exchanged water to the separating funnel.
0ml and 0.1g of sample were added, and I
Shake for 0 minutes. After shaking for 10 minutes and allowing the inorganic powder layer to separate from the aqueous layer, 20 to 30 ml of the lower aqueous layer was collected, placed in a 10 mm cell, and subjected to ion exchange using a blank containing no fine powder at a wavelength of 500 nm. The transmittance is measured using water as a standard, and the value of the transmittance is taken as the degree of hydrophobicity of the inorganic fine powder.

The degree of hydrophobicity of the hydrophobic inorganic fine powder in the present invention is 60%.
or more (more preferably 90% or more).

If the degree of hydrophobicity is less than 60%, it is difficult to obtain a high-quality image due to moisture adsorption of the inorganic fine powder under high humidity.

For the hydrophobization treatment, conventionally known hydrophobization treatment agents and methods are used.

For example, examples of the hydrophobizing agent include a silane coupling agent, silicone oil, and silicone varnish.

Silicone oil and silicone varnish are more preferable than silane coupling agents in terms of hydrophobicity and lubricity.

The silicone oil or silicone varnish used in the present invention is generally represented by the following formula, [R:C+~
3 alkyl group R': alkyl, halogen-modified alkyl, phenyl, modified phenyl, etc. silicone oil-modified group R': C1-3 alkyl group or alkoxy group] For example, dimethyl silicone oil, alkyl-modified silicone oil, α-methyl Examples include styrene-modified silicone oil, chlorphenyl silicone oil, and fluorine-modified silicone oil.

The silicone oil preferably has a viscosity of about 50 to 1000 centistokes at 25°C. Silicone oil with a molecular weight that is too low may generate volatile matter when subjected to heat treatment, etc., and a silicone oil with a molecular weight that is too high may have too high a viscosity, making it difficult to perform treatment operations.

Known techniques can be used for silicone oil treatment.

For example, fine silica powder and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a method may be used in which silicone oil is sprayed onto the base silica. Hydrophobic silica may be prepared by dissolving or dispersing silicone oil in a suitable solvent, mixing it with the base silica fine powder, and then removing the solvent.

More preferably, the inorganic fine powder used in the present invention is first treated with a silane coupling agent and then treated with silicone oil or silicone varnish.

In general, with silicone oil treatment alone, a large amount of silicone oil is needed to cover the surface of the fine powder, making it easy for fine powder aggregates to form during the treatment, and when applied to a developer, the fluidity of the developer may deteriorate. , it is necessary to be very careful about the silicone oil treatment process. Therefore, in order to remove aggregates of fine powder while maintaining good moisture resistance, it is better to treat fine silicic acid powder with a silane coupling agent and then with silicone oil to fully demonstrate the treatment effect of silicone oil. That's what it means.

The silane coupling agent used in the present invention is hexamethyldisilazane or the general formula % formula % R: alkoxy group or chlorine atom m: an integer Y of 1 to 3, an alkyl group, a vinyl group, a glycidoxy group, a methacryl group. Containing hydrocarbon group n: represented by an integer of 3 to 1, typically dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlorosilane, vinyltrichlorosilane, etc. Ethoxysilane, γ
-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, dimethylvinylchlorosilane and the like. .

The fine powder is treated with a silane coupling agent by stirring the fine powder into a cloud shape and reacting with the vaporized silane coupling agent, or by dispersing the fine powder in a solvent and dropping the silane coupling agent. It can be processed using a wet method.

The amount of silicone oil or silicone varnish used in the present invention is preferably 1 to 35 parts by weight, more preferably 2 to 30 parts by weight, per 100 parts by weight of the inorganic fine powder.

If the amount of Soricon oil or Noricon varnish treated is too small, the moisture resistance will not improve and the fine powder will absorb moisture under high humidity, making it impossible to obtain high-quality copy images. If too much Noricon oil or silicone varnish is used,
Since aggregates of inorganic fine powder are likely to form, and free silicone oil or gluecon varnish is formed, there may be a problem that fluidity cannot be improved when applied to a developer.

In the present invention, when a combination of negatively chargeable spherical resin particles and hydrophobic inorganic fine powder is used in a developer, the content of 8 parts by weight of the hydrophobic inorganic fine powder is equal to the content A of the negatively chargeable spherical resin particles. It is preferable that the amount is greater than parts by weight.

The negatively charged spherical resin particles are a developer (excluding carrier).
It is preferable to use the hydrophobic inorganic fine powder in an amount of 0.01 to 1.0 (more preferably 0.03 to 0.5) parts by weight per 100 parts by weight, and the hydrophobic inorganic fine powder contains 0.1 to 3.0 (preferably 0.00 parts by weight).
It is preferable to use 2 to 2.0 parts by weight, more preferably 0.6 to 1.6 parts by weight.

If the content A of the negatively chargeable spherical resin fine particles is more than 1.0 part by weight, the image density tends to decrease, and if the content A is less than 0.01 part by weight, the toner on the surface of the photoreceptor is The effect of preventing fusion is weak. If the content A is in parts by weight or greater than the content B in parts by weight, the fluidity of the developer is reduced and fogging is likely to occur.

Furthermore, in the present invention, negatively charged spherical resin particles,
The use of a combination of hydrophobic inorganic fine powder and fatty acid metal salt fine powder in the developer reduces the generation of ozone when the developer of the present invention is used in an image forming apparatus equipped with contact charging means. This is preferable because it prevents or suppresses the adhesion of toner to the photoreceptor.

The fatty acid metal salt fine powder used in the present invention is preferably positively chargeable and difficult to be transferred, and has a -order average particle size of Il, 1 m.
The following are preferred, and the number of carbon atoms in the fatty acid is preferably 12 or more. Specific examples include zinc stearate and aluminum stearate. The fatty acid metal salt fine powder is preferably used in an amount of 0.01 to 1 part by weight, more preferably 0.05 to 0.67 parts by weight, still more preferably 0.05 to 0.3 parts by weight, per 100 parts by weight of toner particles.

In the present invention, when the content of the fatty acid metal salt fine powder is C parts by weight, parts by weight A, parts by weight C <8 parts by weight and 4X parts by weight
It is preferable to use C so as to satisfy the condition of 8 parts by weight.

If parts by weight A≧parts by weight B, the fluidity of the developer decreases, and if parts by weight 4XC≧parts by weight B, the developer comes into contact with a developer carrier such as a sleeve, a photoreceptor, or a photoreceptor. Contamination is likely to occur on the members to be used, resulting in a decrease in image density and image unevenness.

Other additives may be added to the developer of the present invention as long as they do not have a substantial effect. For example, a fixing aid (for example, low molecular weight polyethylene) and a metal oxide such as tin oxide may be added as a conductivity imparting agent.

In producing the toner of the present invention, the constituent materials are thoroughly kneaded using a thermal kneader such as a hot roll, kneader, or extruder, and then mechanically crushed and classified, and the materials are dispersed in a binder resin solution. A toner can be obtained by spray-drying the binder resin, or by mixing a specified material with the monomers that constitute the binder resin to form an emulsified suspension, and then polymerizing the monomers to obtain the toner. Each manufacturing method can be applied.

Hereinafter, the contact charging process of the present invention applicable to the developer and image forming method of the present invention will be specifically explained.

FIG. 1 is a schematic diagram of a contact charging device showing an embodiment of the present invention. Reference numeral 1 denotes a photoconductor drum which is an object to be charged, and is made by forming an organic photoconductor (○PC) lb as a photoconductor layer on the outer peripheral surface of an aluminum drum base 1a. Rotate with. In this embodiment, the photosensitive drum 1 has an outer diameter of 30 mmφ. A charging roller 2 is a charging member that is brought into contact with the photosensitive drum 1 with a predetermined pressure, and a metal core 2a is provided with a conductive rubber layer 2b, and a surface layer 2c that is a releasable film is provided on the circumferential surface of the roller. This is provided. The conductive rubber layer has a thickness of 0.5 to 10 mm.
(preferably 1 to 5 mm).

The surface layer in this example is a releasable film, and it is preferable to provide a releasable film in view of matching with the developer and image forming method of the present invention. However, if the resistance is too high, the photoreceptor drum 1 will not be charged, and if the resistance is too small, too much voltage will be applied to the photoreceptor drum 1, causing damage to the drum and the formation of pinholes. It is good to have a resistance value (preferably a volume resistivity of 10' to IQ+4 Ωm).

The thickness of the releasable film at this time is preferably within 30 pm (preferably 10 to 30 μm). The lower limit of the thickness of the release film is preferably 5 μm as long as the film does not peel or crease.
It is thought that about.

In this embodiment, the outer diameter of the charging roller 2 is 12 mmφ, and the conductive rubber layer 2b having a thickness of about 3.5 mm is made of ethylene-propylene-diene terpolymer (EPDM).
), a nylon resin (specifically, methoxymethylated nylon) having a thickness of 10 μm was used for the surface layer 2c.

The hardness of the charging roller 2 is 54.5° (ASKER-C
). E is a power supply unit that applies voltage to this charging roller 2, and a predetermined voltage is applied to the core metal 2a (diameter 5
mm). In FIG. 1, E indicates a DC voltage, but it is preferable to use an AC voltage superimposed on a DC voltage.

In order to adjust the electrical resistance value, it is preferable to disperse conductive fine powder such as carbon fine particles in the conductive rubber layer and/or the mold release coating.

Preferred process conditions in this case are shown below.

Contact pressure: 5-500 g/cm AC voltage
: 0,5~5 K V pp AC frequency : 50~3
000H2 DC voltage, -200 to -900v FIG. 2 is a schematic diagram of a contact charging member showing another embodiment of the present invention. Components common to those of the device shown in FIG. 1 are designated by the same reference numerals and will not be described again.

The contact charging member 3 of this embodiment is a blade-shaped member brought into contact with the photoreceptor drum 1 in the forward direction with a predetermined pressure.
This blade 3 has a conductive rubber 3b supported by a metal support member 3a to which a voltage is supplied, and a surface layer 3c serving as a releasable film is provided 6 at the portion in contact with the photoreceptor drum 1. Nylon with a thickness of 10 μm was used as the surface layer 3C. According to this embodiment, there are no problems such as adhesion between the blade and the photoreceptor drum, and the same effects as in the previous embodiment can be obtained.

In the above-described embodiments, a roller-shaped or blade-shaped charging member is used, but the present invention is not limited to this, and the present invention can be practiced with other shapes as well.

In this embodiment, the charging member is composed of a conductive rubber layer and a release coating; however, the charging member is not limited to this, and a high-resistance layer is formed between the conductive rubber layer and the surface layer of the release coating to prevent leakage to the photoreceptor. For example, it is preferable to form a hydrin rubber layer that is subject to small environmental fluctuations.

Polyvinylidene fluoride (PVDF) and polyvinylidene chloride (PVD) are used instead of nylon resin as a release film.
C) may also be used. As the photoreceptor, amorphous silicon, selenium, znO, etc. other than the OPC photoreceptor can also be used. In particular, when amorphous silicon is used for the photoreceptor, compared to when other materials are used, if even a small amount of the softener in the conductive rubber layer adheres to the photoreceptor, image fading will become severe. The effect of applying an insulating film is significant.

In the cleaning process according to the present invention, after the toner image has been transferred, the photosensitive drum is generally cleaned by a cleaning member such as a cleaner blade or roller to remove residual toner and other contaminants, and the surface is repeatedly cleaned. and then subjected to image formation.

It is also possible to perform such a cleaning process simultaneously during a charging process, a developing process, or a transfer process related to electrophotography.

The present invention is particularly effective for an image forming apparatus equipped with a latent image carrier whose surface is formed with an organic compound. When an organic compound forms the surface layer, the binder resin contained in the toner tends to adhere to the surface layer, and toner fusion tends to occur at the contact points, especially when the same material is used. .

The surface material of the latent image carrier used in the present invention includes silicone resin, vinylidene chloride resin, ethylene-vinyl chloride resin,
Examples include styrene-acrylonitrile resin, styrene-methyl methacrylate resin, styrene resin, polyethylene terephthalate resin, and polycarbonate resin. Without being limited to these, other monomers or
Copolymerization, blending, etc. of the exemplified resins can also be used.

The present invention is particularly effective for image forming apparatuses in which the diameter of the latent image carrier is 50 mm or less. This is because in the case of a small diameter drum, the curvature is large even if the linear pressure is the same, so pressure tends to concentrate at the contact area.

It is thought that the same phenomenon occurs with belt photoreceptors, and it is also effective for image forming apparatuses in which the radius of curvature at the transfer section is 25 mm or less.

Further, the image forming method and apparatus of the present invention will be explained with reference to FIG.

A contact charger 502 having a voltage applying means 515 charges the surface of the photoreceptor to a negative polarity, and a digital latent image is formed by image scanning through exposure 505 with laser light.
The latent image is reversely developed using a negatively chargeable component-based magnetic developer 510 in a developing device 509 equipped with a magnetic blade 511 and a developing sleeve 504 containing a magnet. In the developing section, the conductive substrate of the photosensitive drum 501 and the developing sleeve 5
04, an alternating bias, a pulse bias and/or a DC bias is applied by the bias applying means 512. When the transfer paper P is conveyed and reaches the transfer section, the transfer means 503 charges the transfer paper P from the back side (the opposite side to the photosensitive drum side), thereby transferring the developed image (toner image) on the surface of the photosensitive drum. It is electrostatically transferred onto paper P. The transfer paper P separated from the photosensitive drum 501 is subjected to a fixing process to fix the toner image on the transfer paper P by a heating and pressure roller fixing device 507.

The one-component developer remaining on the photosensitive drum after the transfer process is
It is removed by a cleaning device 508 having a cleaning blade. The photosensitive l-ram 501 after cleaning is
The charge is removed by the erase exposure 506, and the charger 50
The steps starting from the charging step in step 2 are repeated.

The electrostatic image carrier (photosensitive drum) has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. A non-magnetic cylindrical developing sleeve 504 serving as a toner carrier rotates in the developing section so as to move in the same direction as the surface of the electrostatic image holder. Inside the nonmagnetic cylindrical sleeve 504, a multipolar permanent magnet (magnet roll) serving as a magnetic field generating means is arranged so as not to rotate. One-component insulating magnetic developer 510 in developing device 509
is applied onto a non-magnetic cylindrical surface, and the toner particles are given, for example, a negative triboelectric charge by rapid rubbing between the surface of the sleeve 504 and the toner particles. Furthermore, a magnetic doctor blade 511 made of iron is placed close to the cylindrical surface (with a spacing of 50
μm to 500 μm), the thickness of the developer layer can be reduced by placing it opposite to one magnetic pole position of a multipolar permanent magnet.
30 μm to 300 μm) and uniformly, a developer layer thinner than the gap between the electrostatic image carrier 501 and the toner carrier 504 in the developing section is formed so as not to be in contact with each other.

By adjusting the rotational speed of the toner carrier 504, the sleeve surface speed is substantially equal to or close to the speed of the electrostatic image holding surface. Instead of iron, a permanent magnet may be used as the magnetic doctor blade 511 to form opposing magnetic poles. In the developing section, an AC bias or a pulse bias may be applied between the toner carrier 504 and the electrostatic image holding surface by the bias means 512. This AC bias has f of 2 (10-4, OO
It is sufficient if OHz XV p p is 500 to 3,000 OOV.

When the toner particles are transferred to the developing area, the toner particles are transferred to the electrostatic image side by the action of the electrostatic force of the electrostatic image holding surface and the alternating current bias or pulse bias.

Instead of the magnetic doctor blade 511, an elastic blade made of an elastic material such as silicone rubber may be used to control the thickness of the developer layer by pressing and apply the developer onto the developer carrier.

An electrophotographic apparatus is constructed by combining a plurality of components such as the above-mentioned photoreceptor, developing means, and cleaning means into an apparatus unit, and this unit is configured to be detachable from the apparatus main body. It's okay. For example, at least one of the charging means, the developing means, and the cleaning means may be integrally supported with the photoreceptor to form a single unit that can be attached to and detached from the main body of the apparatus, and a guide means such as a rail of the main body of the apparatus may be used. It may be configured to be detachable. At this time, the above-mentioned device unit may include a charging means and/or a developing means.

When the image forming apparatus of the present invention is used as a facsimile printer, the optical image exposure 505 is exposure for printing received data. FIG. 6 is a block diagram showing an example of this case.

The controller 611 controls the image reading unit 610 and the printer 6.
Controls 19. The entire controller 611 is the CPU6
17. The read data from the image reading unit is transmitted to the partner station through the transmitting circuit 613.

Data received from the partner station is sent to a printer 619 through a receiving circuit 612. Predetermined image data is stored in the image memory. A printer controller 618 controls a printer 619. 614 is a telephone.

The image received from the line 615 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 612, and then the CPU 617 decodes the image information and sequentially stores it in the image memory 616. Ru. Then, once at least l pages of images are stored in memory 616,
Record an image of that page. The CPU 617 reads one page of image information from the memory 616 and sends the decoded one page of image information to the printer controller 618. When the printer controller 618 receives one page of image information from the CPU 618, it controls the printer 619 to record the image information of that page.

The CPU 617 receives the next page while the printer 619 is recording.

As described above, images are received and recorded.

The basic configuration and features of the present invention have been described above, and the method of the present invention will be specifically explained below based on Examples. However, this does not limit the embodiments of the present invention in any way. Parts in the examples are parts by weight.

Example 2 200 parts of cumene was placed in a reactor and the temperature was raised to reflux temperature. To this were added 85 parts of styrene monomer, 15 parts of acrylic acid monomer and 8.5 parts of di-tert-butyl peroxide.
parts were mixed. Furthermore, under cumene reflux (146℃~156℃
The solution polymerization was completed at 10°C (°C) and the cumene was removed by increasing the temperature.

The obtained styrene-acrylic acid copolymer is soluble in THF, Mw=3,500, Mw/Mn=2.
52, the molecular weight where the main peak of GPC is located is 3.3
,00, Tg=56°C.

30 parts of the above copolymer was dissolved in the following monomer mixture to prepare a mixed solution.

Add 0% of the partially saponified polyvinyl alcohol to the above mixed solution.
170 parts of water in which 1 part was dissolved was added to form a suspension dispersion. The suspension dispersion was added to a reactor containing 15 parts of water and purged with nitrogen, and a suspension polymerization reaction was carried out at a reaction temperature of 70 to 95° C. for 6 hours. After the reaction was completed, the mixture was filtered, dehydrated, and dried to obtain a copolymer composition. In the composition, a styrene-acrylic acid copolymer and a styrene-acrylic acid-n-butyl acrylate copolymer were uniformly mixed. The obtained resin composition has TH
When the molecular weight distribution of the F-soluble component was measured, there were peaks at approximately 3,500 and 31,000 positions in the GPC chart, Mn = 5,100, M w = 115.
, OOO, M w / M n =22.5, and the molecular weight of 10,000 or less was 27 wt%. Furthermore, the Tg of the resin is 5
The temperature was 9°C, and the glass transition point Tg+ of the components of 10,000 or less separated by GPC was 57°C.

The acid value of this copolymer was 22.0.

200 parts of cumene was placed in a reactor and heated to reflux temperature. The following mixture was subjected to solution polymerization under refluxing of cumene, and after the reaction was completed, the temperature was raised to remove cumene. The obtained styrene-acrylic acid n-
Butyl copolymer has Mw=6,900, Mw/L
It had a main peak at i.sub.2.36, molecular weight 7,200, and Tg=64.degree.

30 parts of the above styrene-maleic acid n-butyl half ester copolymer was dissolved in the following monomer mixture to form a mixture, and the same procedure as in Synthesis Example] was carried out.
A composition of a butyl half ester copolymer and a styrene-n-butyl acrylate-n-butyl maleate half ester copolymer was obtained.

The acid value of this copolymer was 20.6.

200 parts of cumene was placed in a reactor, and the temperature was raised to reflux temperature. To this was added a mixture of 78 parts of styrene monomer, 15 parts of n-butyl acrylate monomer, 7 parts of n-butyl maleate half ester, 0.3 parts of divinylbenzene, and 1.0 parts of tert-butyl peroxide under refluxing of cumene. The mixture was added dropwise over 4 hours, the polymerization reaction was continued for another 4 hours, and then the solvent was removed by ordinary vacuum distillation to obtain a copolymer. The obtained copolymer has M w = 250,000, M w /
M n = 11, 0, Tg = 60°C.

The acid value of this copolymer was 19.5.

Synthesis Example 3 was carried out in the same manner as in Synthesis Example 3, except that 82 parts of styrene monomer and 18 parts of n-butyl acrylate monomer were used, and n-butyl maleate half ester was not used.

The acid value of this copolymer was 0.4.

Synthesis Example 3 was repeated except that 82 parts of the styrene monomer and 3 parts of n-butyl maleate half ester were used.

The acid value of the obtained copolymer was 7.3.

Synthesis Example 3 was carried out in the same manner as in Synthesis Example 3 except that the styrene monomer was changed to 70 parts and the maleic acid n-butyl half ester was changed to 15 parts.

The acid value of the obtained copolymer was 48.

- 100 parts of the resin composition of Synthesis Example 1 - 100 parts of magnetic fine powder (BET value 8.6 bo/g) - 1.1 parts of negative charge control agent (monoazo dye-based chromium complex) - 3 parts of low molecular weight polypropylene (M w
= 6,000) The above mixture was melt-kneaded with a twin-screw extruder heated to 140°C, the cooled kneaded product was coarsely ground with a hammer mill, and the coarsely ground product was pulverized with a wet mill, and the obtained The finely pulverized powder is classified by air, and then ultra-fine powder and coarse powder are simultaneously strictly classified and removed using a multi-division classifier that utilizes the Coanda effect (elbow classifier manufactured by Nippon Steel Mining Co., Ltd.), resulting in negative particles with a volume average particle size of 64 μm. Chargeable insulating magnetic toner (I)
(7g, 57°C) was obtained.

・Resin composition of Synthesis Example 2 100 parts ・Magnetic fine powder (BET value 8.6 rrr/g) 110 parts ・Negative charge control agent 1.1 parts (monoazo dye-based chromium complex) ・Low Molecular weight polypropylene 3 parts (M w
= 6,000) The above mixture was treated in the same manner as in Production Example 1 to obtain negatively charged insulating magnetic toners (II) and (III) having different average particle sizes.

1 point higher" - Resin composition of Synthesis Example 3 100 parts - Magnetic fine powder (BET value 8.6 d/g) 80 parts - Negative charge control agent 1.1 parts (monoazo dye-based chromium complex) - Low Molecular weight polypropylene 3 parts (M w
= 6,000) The above mixture was treated in the same manner as in Production Example 1 to obtain a negatively charged magnetic toner (rV).

1 "French" The same procedure as Production Example 1 was carried out except that the resin composition of Synthesis Example 4.5 was used instead of the resin composition of Synthesis Example 3, and the negatively charged insulating magnetic toner (V) and (VD were Obtained.

"Lsen" manufactured by Hii 1 - 100 parts of the resin composition of Comparative Synthesis Example 1 - 90 parts of magnetic fine powder (BET value 7.7 rrr/g) - 1.1 parts of negative charge control agent (chromium salicylate) complex) ・3 parts of low molecular weight polypropylene (M w
= 6,000) A negatively charged magnetic toner (
■) (7g, 55°C) was obtained.

The particle size distribution of the above toner is shown in Table 1 below.

゛・0 1~8 Ratio 1~4 True spherical negatively charged spherical resin fine particles with a major axis/minor axis ratio of about 1 and hydrophobic silica are added to the magnetic toner and mixed in a Hennel mixer, and a developer is prepared. And so.

This developer was applied to an image forming apparatus (canon LBP-8II modified machine) having a contact charging device as shown in FIG.
An actual photographic test was carried out at normal temperature and normal humidity (25° C., 60% RH) in which toner images were continuously formed by a reversal development method at a speed of 16 sheets per minute by applying 00 Hz, 2000 Vpp).

As described above (the charging roller 2 has a diameter of 12 mm, the core metal has a diameter of 5 mrn, and the conductive rubber layer 2b has a diameter of about 3.5 mrn).
The release coating made of methoxymethylated nylon has a thickness of 20 μm and a total pressure of 1.2 kg.
(linear pressure of 55 g/cm) and pressed against the OPC photoreceptor.

A schematic diagram of the image forming apparatus is shown in FIG. In the image forming apparatus, the toner layer thickness on the sleeve is 130 μm, the closest gap between the sleeve and the OPC photoreceptor is 300 μm, and DC bias (-500 V) and AC bias (18
A surface exposure test was conducted without applying a voltage of 0 Hz and 1600 Vpp to the developing sleeve.

The results are shown in Table 5. The image density in Table 5 is the average of the densities of a solid black square image of 5 mm on a side measured at 5 points, and the minute dot reproducibility is as shown in Fig. The reproducibility of an image of a 50 μm checker pattern was observed and evaluated using a microscope, focusing on the sharpness of the image and the scattering in non-image areas. Toner fusion to the OPC photoreceptor was evaluated by observing the surface of the OPC photoreceptor and toner images after 10,000 images were printed. .

The PC photoreceptor used had a surface abrasion property of 2.5 x I 0-2c tri as measured by a taper abrasion tester.

Table 2 shows the physical properties of the negatively charged resin particles, Table 3 shows the physical properties of the hydrophobic silica, Table 4 shows the physical property values of the developer, and Table 5 shows the composition and evaluation results of the developer.

The evaluation criteria are shown below.

Fogging ○... is very bad △... fogging but usable ×... not practical Photoreceptor fusion ○... no fusion at all ○△... 1~1 in A4 peta black 3 white spots caused by toner fusion △ ... 3 to 10 white spots caused by toner fusion on A4 solid black X ... 10 or more toner fusion spots on A4 solid black Reproducibility of caused white dots (out of 100) ○ ... 2 or less defects ○ △ ... 3 to 5 defects △ ... 6 to 10 defects × ... 11 or more defects" L animals j - 100 parts of the resin composition of Synthesis Example 1 - 60 parts of magnetic fine powder (BET value 8.6 bo/g) - 1 part of negative charge control agent (monoazo dye-based chromium complex) - 3 parts of low molecular weight polypropylene ( Mw
= 6,000) The above mixture was melt-kneaded with a twin-screw extruder heated to 140°C, the cooled kneaded product was coarsely ground with a hammer mill, and the coarsely ground product was pulverized with a jet mill to obtain the The finely pulverized powder was classified by air to obtain a negatively charged insulating magnetic toner (■) (7 g, 57° C.) having a volume average particle diameter of 12 μm.

111] - Resin composition of Synthesis Example 2 100 parts - Magnetic fine powder (BET value 8.6 rrr/g) 6 parts - Negative charge control agent 1 part (monoazo dye-based chromium complex) - Low molecular weight polypropylene 3 part (Mw=
6,000) The above mixture was prepared in the same manner as in Production Example 6 to produce magnetic toner (IX).
I got it.

・Resin composition of Synthesis Example 3 100 parts ・Magnetic fine powder (BET value 8.6 rrr/g) 60 parts ・Negative charge control agent 1 part (monoazo dye-based chromium complex) ・Low molecular weight polypropylene Part 3 (Mw
= 6, OOO) The above mixture was treated in the same manner as in Production Example 6 to obtain a magnetic toner (X).

JJ2JU made by Kujibori - 100 parts of the resin composition of Comparative Synthesis Example 1 - 60 parts of magnetic fine powder (BET value 7.7 rrr/g) - 3 parts of negative charge control agent (salicylic acid-based chromium complex) - Low molecular weight polypropylene 3 Department (M w
= 6,000) A magnetic toner Oa) was obtained using the above components in the same manner as in Production Example 1.

Manufacturing Example 8 was repeated except that the resin composition of Synthesis Example 4.5 was used instead of the resin composition of Synthesis Example 3, and magnetic toner π
, got a store.

9-17 and 5-7 Negatively charged spherical resin particles and hydrophobic silica fine powder or silica fine powder are added to the above magnetic toner and mixed in a Henschel mixer to form negatively charged spherical resin particles and hydrophobic silica fine powder or A developer containing a toner in which fine silica powder was mixed (externally added) was obtained.

Next, each of the prepared negatively chargeable component-based magnetic developers was applied to a DC voltage (-700 V) using an image forming apparatus (Canon LBP-8I [modified machine]) having a contact charging device shown in No. 111J. ) and AC voltage (600Hz.

A real photo test was carried out at room temperature (25°C, 60% RH) in which a toner image was formed continuously using a reversal development method at a printing speed of 16 sheets (A4)/min by applying 1500 VI) P), and the printout image was evaluated. At the same time, the charging member (
(roller type) and the physical properties of water sampling warp force on the surface of the photosensitive drum,
Table 7 shows the composition of the developer and the evaluation results. The charging device used was the roller type shown in FIG. 1 in all cases, except for the blade type shown in FIG. 2 in Example 15.

Claims (4)

[Claims] (1) Toner and average particle size of 0.03 to 1.0 μm
And the specific electrical resistance is 10^6 to 10^1^2 Ω・c
1. A developer for developing an electrostatic image, characterized by containing negatively chargeable resin fine particles of m. (2) A contact charging means for charging a charged object while contacting it to carry an electrostatic charge image, and a toner and an average particle size of 0.03 to 1.01 μm and a volume electric resistance of 10^6 to 1.
It is characterized by having a developing means for developing an electrostatic charge image formed on a charged body with a developer for developing an electrostatic charge image containing negatively chargeable spherical resin fine particles of 0^1^2 Ω·cm. Image forming device. (3) An object to be charged, a contact charging means, a toner, an average particle size of 0.03 to 1.0 μm, and a volume electric resistance of 10^6 to 1
a developing means for developing an electrostatic charge image formed on a charged body with a developer for developing an electrostatic charge image containing negatively chargeable spherical resin fine particles of 0^1^2 Ω·cm; An apparatus unit characterized in that the means and the developing means are integrally supported together with the object to be charged to form a unit, forming a single unit that can be freely attached to and detached from the apparatus main body. (4) The electrophotographic apparatus includes a receiving means for receiving image information from an electrophotographic apparatus and a remote terminal, and the electrophotographic apparatus includes a contact charging means for charging an object to be charged while contacting it to carry an electrostatic charge image. and a toner with an average particle size of 0.03 to 1.0 μm and a volume electrical resistance of 1
A developer for developing an electrostatic charge image containing negatively chargeable spherical resin fine particles of 0^6 to 10^1^2 Ωcm, and having a developing means for developing an electrostatic charge image formed on a charged object. A facsimile device characterized in that it is an image forming device.