JP2922051B2 - Electrostatic latent image developer and image forming method - 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 an electrostatic latent image developer used in a developing process in electrostatic printing and the like, and an image forming method using the same.

[0002]

2. Description of the Related Art F. Since the invention of electrophotography by Carlson (U.S. Pat. No. 2,297,691),
Various two-component developers have been proposed (U.S. Pat. Nos. 2,618,551 and 2,618,52).
No. 2, No. 2,573,881 and No. 2,638,416) and after the invention of the magnetic brush developing method (U.S. Pat. No. 2,786,439). Attempts have been made to apply a resin coat to the carrier of a two-component developer to improve charging characteristics, toner scattering and moisture resistance.

A two-component developer is composed of a two-component system of a toner and a carrier. The carrier charges the toner and transports the toner to a developing zone. Only the toner adheres to the electrostatic latent image and is developed to form a visible image. Is formed.

Typical carrier (non-coated carrier)
Consists of magnetic particles such as iron, magnetite, and ferrite. Although this magnetic powder carrier has a simple structure and good durability, it has a relatively small electric resistance, so that the toner tends to be poorly charged, and the toner is liable to be scattered or fogged. Further, since the toner is heavy, the toner component adheres to the carrier due to the impact due to the stirring in the developing device, and there is a problem that the spent is easily generated.

[0005] When the spent occurs, the charging ability of the carrier is reduced, which has an adverse effect on the image quality such as generation of fog and reduction in image density. For this reason, the life of the developer is shortened, and periodic replacement of the developer is inevitable.

On the other hand, a magnetic powder carrier (coated carrier) in which the surface of magnetic particles is coated with a resin or the like has a high resistance, so that the chargeability of the toner becomes good,
It is possible to prevent the toner from scattering in the machine and fogging. However, it is inevitable that the coating peels off with repeated use, and in that case, scattering and fogging in the machine occur. In particular, in a small-sized machine in which the developing unit is made compact, a large shearing force is applied at the time of mixing and stirring with the toner, so that the coating is peeled off and the durability is easily deteriorated.

[0007] A small-diameter magnetic resin carrier in which magnetic fine particles are dispersed in a binder resin is also known (Japanese Patent Laid-Open No. Sho 47/47).
Nos. 13954, 49-51950, 5
However, since the resistance is increased by the resin, the charging property to the toner is excellent. There is also a report that the use of a resin carrier reduces the stress applied to the carrier and prolongs the life of the developer.
eport, Vol. 26, no. 4, Aug. , (1
982)). However, since the specific gravity (true density) of the magnetic resin carrier is small, the magnetic resin carrier is attached and transported on the photoconductor together with the toner at the time of development, so that so-called "carrier pulling" is likely to occur.

Further, by combining a magnetic resin carrier obtained by dispersing magnetic fine powder in a binder resin, a magnetic powder carrier comprising ferromagnetic particles, and an insulating toner into a developer, a soft developer is obtained. It has been reported that a magnetic brush of ears is formed and that aggregation of a magnetic powder carrier is prevented (Japanese Patent Laid-Open No. Sho 59-192262). However, since ordinary insulating toner is used as the toner, spent printing occurs and image deterioration due to continuous printing occurs.

It has been proposed to prevent carrier deterioration by adding a third substance other than the toner and the carrier (Journal of the Society of Electrophotography, Vol. 23, No. 1, 1984).
Year: PFP method and high quality of copy image, Makoto Sumida), also in this case, since the third substance is developed, it is difficult to keep the obtained image density constant.

Further, in a developing system in which toner is attracted to a carrier by electrostatic force, the bonding force between the carrier and the toner fluctuates due to a change in environment, and particularly under high humidity, the toner scatters inside the printer and causes scatter inside the machine. Cheap. It is considered that the cause of this is that the toner component is spent on the surface of the carrier, and the bonding force between the carrier and the toner is insufficient due to poor charging of the toner and generation of the oppositely charged toner.

On the other hand, in recent years, a photoconductor using an amorphous silicon (a-Si) photoconductor layer has been receiving attention in addition to the conventional Se photoconductor and organic optical semiconductor. The a-Si-based photoconductor has no problem in terms of safety as compared with the Se-based photoconductor,
Further, it has excellent durability and has a longer life than the device unit. However, on the other hand, the a-Si-based photoreceptor tends to leak charge after a long-term use, and tends to cause so-called "image deletion".

The use of abrasives as a countermeasure against such image deletion has been known for a long time. For example, the addition of strontium titanate fine particles to a developer (Japanese Patent Application Laid-Open No. 61-1986)
No. 2,788,861), use of a cleaning member having a Mohs' hardness of 2.5 to 7.0 (Japanese Patent Application Laid-Open No. 59-88776), and a method of using abrasives and fine particles of the same level as the surface layer of an a-Si drum (particularly, US Pat. And the like, and it has been reported that alkaline earth metals, carbonates, and the like are effective for image flow of an a-Si photoreceptor (Japanese Patent Application Laid-Open No. SHO 61-61). 231564).

However, each of the above-mentioned polishing methods has a weak polishing force, and the effect of preventing the image flow of the a-Si photosensitive member is insufficient. In addition, if an attempt is made to increase the polishing force, the size of the image forming apparatus becomes large and cannot be adopted for a small machine.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developer and an image forming method capable of preventing the occurrence of spent of a carrier and stably forming an image.

[0015]

According to the present invention, there is provided a developer for an electrostatic latent image comprising: (a) a magnetic resin carrier in which magnetic fine particles are dispersed in a binder resin; and (b) a magnetic resin substantially comprising magnetic particles themselves. It is characterized by containing a powder carrier and (c) an abrasive magnetic toner having abrasive particles fixed on the surface.

Further, according to the image forming method of the present invention, an electrostatic latent image is formed on an a-Si photosensitive member having an amorphous silicon (a-Si) photosensitive layer while being conveyed.
(A) a magnetic resin carrier in which magnetic fine particles are dispersed in a binder resin, (b) a magnetic powder carrier substantially consisting of magnetic particles themselves, and (c) abrasive particles fixed to the surface. After developing with an electrostatic latent image developer containing the obtained abrasive magnetic toner, and then transferring the abrasive magnetic toner that forms a toner image on the surface of the photoconductor, it remains on the conveyed photoconductor. The pressing member is pressed against the partially untransferred abrasive magnetic toner, and the surface of the a-Si photosensitive member is polished by the polishing force of the abrasive magnetic toner and the pressing force of the pressing member.

Further, a toner image is formed on the a-Si photosensitive layer by using the above-mentioned developer, and then the toner image is transferred to a material to be transferred. And the surface of the photoreceptor can be polished with the remaining toner, and the polishing effect is further improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In the developer of the present invention, (a) a magnetic resin carrier and (b) a magnetic powder carrier are used in combination.

(A) The magnetic resin carrier is obtained by dispersing magnetic fine particles in a binder resin. Positive or negative chargeable fine particles may be fixed on the surface of the carrier, or a surface coating layer may be provided. it can. (A)
The charging characteristics such as the polarity of the magnetic resin carrier can be controlled by the material of the binder resin, the chargeable fine particles, and the type of the surface coating layer.

Examples of the binder resin used in the magnetic resin carrier include thermoplastic resins such as vinyl resins represented by polystyrene resins, polyester resins, nylon resins and polyolefin resins, and curable resins such as phenol resins. Is done.

Examples of the magnetic fine particles include magnetite, spinel ferrite such as gamma iron oxide, and metals other than iron (M
n, Ni, Mg, Cu, etc.), and magnetoplumbite-type ferrites such as spinel ferrite and barium ferrite, and iron and alloy particles having an oxide layer on the surface. The shape may be any of a granular shape, a spherical shape, and a needle shape. In particular, when high magnetization is required, it is preferable to use ferromagnetic fine particles such as iron. In consideration of chemical stability, it is preferable to use ferromagnetic fine particles of magnetite, spinel ferrite containing gamma iron oxide, and magnetoplumbite ferrite such as barium ferrite. By appropriately selecting the type and content of the ferromagnetic fine particles, a magnetic resin carrier having a desired magnetization can be obtained. The magnetic fine particles are suitably added to the magnetic resin carrier in an amount of 50 to 90% by weight.

Such a magnetic resin carrier can be manufactured, for example, by the following method. (1) The magnetic fine particles and the insulating binder resin are melted and mixed, and then cooled and finely pulverized. (2) A melt spray drying method in which a molten mixture of magnetic fine particles and an insulating binder resin is sprayed.

(3) A monomer or prepolymer is reacted and cured in an aqueous medium in the presence of magnetic fine particles,
A method for producing a magnetic resin carrier in which magnetic fine particles are dispersed in a condensation type binder.

It is also possible to modify the surface by fixing positively or negatively chargeable fine particles or conductive fine particles to the surface of the obtained carrier particles, or to control the chargeability of the magnetic resin carrier by coating with a resin. it can. As the surface coating material, a silicone resin, an acrylic resin, an epoxy resin, a fluorine-based resin, or the like is used. By coating these resins on the surface and curing the resin to form a coat layer, the charge applying ability can be improved. .

The chargeable fine particles or the conductive fine particles are fixed to the surface of the magnetic resin carrier by, for example, uniformly mixing the magnetic resin carrier and the fine particles, attaching the fine particles to the surface of the magnetic resin carrier, and then mechanically mixing the fine particles. -It is performed by applying a thermal impact force and driving the fine particles into the magnetic resin carrier and fixing them. In this case, the fine particles are not completely embedded in the magnetic resin carrier, but are fixed so that a part thereof protrudes from the surface of the magnetic resin carrier. This fixing method is the same as the method of fixing the abrasive fine particles to the toner described later.

As the chargeable fine particles, organic and inorganic insulating materials are used. Specifically, as the organic material, it is possible to use organic insulating fine particles such as polystyrene, a styrene-based copolymer, an acrylic resin, various acrylic copolymers, nylon, polyethylene, polypropylene, a fluororesin, and a crosslinked product thereof. As for the charging level and polarity, a desired level of charging and polarity can be obtained depending on the material, polymerization catalyst, surface treatment and the like.

As the inorganic material, negatively chargeable inorganic fine particles such as silica and titanium dioxide, and positively chargeable inorganic fine particles such as alumina are used. The conductive fine particles include carbon black, tin oxide, conductive titanium oxide (a conductive material coated on titanium oxide),
It is desirable to use silicon carbide or the like, which does not lose conductivity due to oxidation by oxygen in the air.

The average particle size of the magnetic resin carrier is 10 to 10
0 μm is suitable, preferably 20 to 80 μm, and more preferably 30 to 70 μm.

(B) As the magnetic powder carrier, a magnetic powder such as iron, magnetite, or ferrite is used as in the case of the magnetic fine particles described above. In particular, the ferrite-based carrier has an extremely hard surface and is not polished by the abrasive toner itself. As the magnetic powder carrier, a non-coated carrier using the magnetic powder as it is is preferable from the viewpoint of durability stability, but a coated carrier obtained by coating the magnetic powder with a resin can also be used.

The average particle size of the magnetic powder carrier is 10 to 10
0 μm is suitable, preferably 20 to 80 μm, and more preferably 30 to 70 μm. The magnetic force of the carrier is desirably about 50 to 80 emu / g, more preferably about 60 to 70 emu / g in saturation magnetization at 5 KOe for both the resin carrier and the powder carrier.

In the present invention, a magnetic resin carrier and a magnetic powder carrier are used in combination, but the functions are separated from each other.
That is, the magnetic resin carrier mainly performs a charge imparting (charging) action to the toner particles. The magnetic powder carrier has a function of transporting and mixing the developer.

Since the magnetic resin carrier has a smaller true specific gravity and an apparent specific gravity than the magnetic powder carrier, the magnetic resin carrier has a large surface area per unit weight, and has a large ability to impart a charge to toner particles even in a small amount. Further, even in a developing device of a small printer in which a large shearing force is applied at the time of mixing and stirring, the generation of spent is reduced, and the impact during stirring of the magnetic powder carrier can be reduced. Further, even if the magnetic resin carrier has been subjected to surface treatment such as surface coating, since the stress at the time of stirring is relatively small, the surface coating material (surface treatment material) is hardly polished and peeled off by the abrasive toner. Therefore, in addition to controlling the surface state by adding a charge control agent to the resin carrier, a constant charge can be stably applied to the toner by performing a surface coating and a surface treatment.

On the other hand, by using the magnetic powder carrier, "carrier pulling" of the magnetic resin carrier can be prevented. When the magnetic resin carrier is used alone, "carrier pulling" tends to occur because the specific gravity is small, the charge per weight (specific charge Q / M) is large, and the magnetic force is relatively weak. In particular, in order to take advantage of the characteristics of the magnetic resin carrier, it is desirable to set the particle size to a small diameter (for example, 100 μm or less). However, when the particle size is reduced, “carrier pulling” is more likely to occur. When the particle size of the magnetic resin carrier becomes large, the image quality becomes coarse and the toner density cannot be increased to a certain level or more. On the other hand, if a magnetic powder carrier that reflects the magnetic properties of the ferromagnetic material is used as it is, the ears from the sleeve become ears centered on the magnetic powder carrier, and when leaving the development zone,
The magnetic resin carrier is attracted to the magnetic powder carrier,
The magnetic resin carrier does not move to the photoconductor together with the toner.

The mixing ratio between the magnetic resin carrier and the magnetic powder carrier is determined according to the charge level of the toner. That is, when the charge level of the toner is low, the Q / M of the entire developer can be controlled by increasing the ratio of the magnetic resin carrier having the opposite charge to the toner. The mixing ratio of the (a) magnetic resin carrier and the (b) magnetic powder carrier is preferably in a range of (a) / (b) = 5 to 75/95 to 25, more preferably 5 to 50/50 by weight ratio. 95-50
It is. When a carrier system composed of only a magnetic resin carrier is formed, carrier pulling occurs and whitening occurs in an image.

FIG. 1 is a model diagram of the toner of the present invention.
Toner 11 has abrasive fine particles 1 on the surface of toner base particles 13.
5 are fixedly formed.

To fix the abrasive fine particles 15 to the surface of the toner base particles 13, for example, the toner base particles 13 and the abrasive fine particles 15 are uniformly mixed, and the abrasive fine particles 15 adhere to the surface of the toner base particles 13. After that, a mechanical / thermal impact force is applied to fix the abrasive particles 15 into the toner base particles 13. The abrasive fine particles 15 are not completely embedded in the toner base particles 13, but are fixed so that a part thereof protrudes from the toner base particles 13.

Such a fixing device for the abrasive fine particles 15 is commercially available as a surface reforming device or system, and examples thereof are as follows. (1) Dry mechanochemical method: Mechanochemical (Okada Seiko Co., Ltd.) Mechanofusion system (Hosokawa Micron Co., Ltd.)

(2) High-speed impact method in airflow: Hybridization system (Nara Machinery Co., Ltd.) Kryptron system (Kawasaki Heavy Industries, Ltd.)

(3) Wet method: Dispercoat (Nissin Flour Milling Co., Ltd.) Coatmizer (Freund Sangyo Co., Ltd.)

(4) Heat treatment method: Surfusing (Nippon Pneumatic Industries, Ltd.) (5) Others: Spray dry (Okawara Kakoki Co., Ltd.)

As the abrasive fine particles 15, fine particles having high hardness, for example, fine particles of a metal oxide such as alumina and zirconia are used. Also, as the surface protection layer 21, Si
Considering the application to an a-Si photoconductor provided with C,
Since the Mohs hardness of the C layer is about 8, the Mohs hardness is 8
As described above, preferably 8 to 9 fine particles are preferable.

The size of the abrasive particles 15 is preferably D / d = 10 to 50, more preferably 10 to 50, where D is the average particle size of the toner base particles 33 and d is the average particle size of the abrasive particles. It is in the range of 40. Thereby, the abrasive particles 15 are firmly fixed to the surface of the toner base particles 13,
Further, the polishing effect by the abrasive fine particles 15 increases.

The abrasive fine particles 15 may be subjected to a surface treatment for the purpose of charge adjustment and hydrophobicity. Further, for the purpose of adjusting the fluidity or the like, other fine particles may be used in combination.

Further, the toner 11 of the present invention is provided with magnetism. This magnetism can be provided by adding a magnetic substance such as magnetite or ferrite to the inside of the toner base particles 13 or by fixing the magnetic body to the surface of the toner base particles 13 in the same manner as the abrasive fine particles 15.

The abrasive magnetic toner of the present invention preferably has a saturation magnetization of 2 to 20 emu / g at 5 KOe, more preferably 3 to 15 emu / g, and still more preferably 5 to 10 emu / g. If the magnetic force is too small, scattering inside the machine cannot be effectively prevented, while if the magnetic force is too large, a sufficient image density cannot be obtained.

As the toner base particles 13, those having the same constitution as the conventional toner itself are used, and for example, a binder resin, a magnetic substance, a colorant, a charge control agent, an offset preventing agent, and the like can be compounded. As the binder resin, a vinyl resin represented by a polystyrene resin such as a styrene-acryl copolymer, a polyester resin, or the like is used.

Magnetic substances include magnetite and ferrite; colorants include carbon black and various pigments and dyes; charge control agents include quaternary ammonium compounds, nigrosine, nigrosine base, crystal violet, and triphenylmethane. Compounds and the like; olefin waxes such as low molecular weight polypropylene, low molecular weight polyethylene or modified products thereof can be used as an anti-offset agent and a fixing improving aid.

The toner base particles of the present invention can be obtained by a conventional method, for example, by melt-kneading the components with a twin-screw extruder, a kneader, or the like, followed by pulverizing with a jet mill or the like and classification. Generally, the average particle size of the toner is preferably 20 μm or less, and more preferably 15 μm or less.

When such a toner 11 is used, the toner 11 polishes the surface of the magnetic powder carrier when stirring and mixing the developer, and removes the spent material fused to the powder carrier surface. Therefore, the spent does not deposit or grow more than a certain amount, and stable image quality can be obtained over a long period of time.

For the spent, the amount of spent for both carriers is determined from the resistance value and the total carbonaceous material. If the resin used in the resin carrier is insoluble in the solvent, see "Study of Magnetic Brush Developing Machine", Takafumi Arimura, Journal of the Society of Electrophotography, Vol. 9,
No. 2 (1981). Further, the measurement accuracy can be improved by quantifying a specific element in the carrier.

Further, by combining a carrier-based abrasive magnetic toner using two types of magnetic carriers, the toner is bonded to the carrier by electrostatic force and magnetic force due to charging, and scattering inside the machine, especially inside the environment under environmental changes. Effectively prevented.

In particular, the developer of the present invention is suitable for application to an a-Si photosensitive member. That is, in an image forming system using an a-Si photoconductor, a relatively low photoconductor charging potential and a developing bias voltage are set due to restrictions on the photoconductor characteristics. It will be difficult. Further, since the SiC layer forming the surface layer of the a-Si photosensitive drum has a strong activity and easily attaches the toner physically, the toner adheres particularly at a high temperature and fog is easily generated. On the other hand, if the toner is held by a strong electrostatic force, the toner passes through the cleaning blade and toner adheres to the photosensitive drum.

Further, at the same time, the toner 11
When the toner 11 comes into contact with and rubs against the surface layer of the photoreceptor as in the case of development or cleaning, the surface of the photoreceptor is effectively polished, and the SiC layer is used as the surface layer. It is effective for a-Si type photoreceptors.

FIG. 2 is a sectional view showing the layer structure of the photosensitive layer of the a-Si photosensitive member 21. On the conductive substrate 23,
Light absorbing layer 25 made of Si: Ge: H or the like, Si: H:
A carrier injection blocking layer 27 made of B: O or the like, a carrier excitation / transport layer 29 (photoconductive layer) made of Si: H or the like, and a surface protection layer 31 are sequentially laminated.

The surface protection layer 31 is typically formed of SiC. This SiC layer (surface protective layer 31) is not smooth, has many fine protrusions (cones), has strong hydrophilicity, and adheres ion products generated by corona discharge. Therefore, when continuous printing is repeated or printing is started under high humidity conditions, toner adheres to the photosensitive drum and toner filming occurs.
Adhesion of a hydrophilic compound such as ammonium nitrate as an ion product occurs, and the charge of the photoconductor leaks, so-called "image deletion" occurs. Moreover, these products have a strong tendency to accumulate between the minute projections of the SiC layer, which is the surface protective layer 31, so that "image deletion" cannot be prevented by ordinary cleaning.

On the other hand, the abrasive toner of the present invention comprises:
The fine abrasive particles 15 polish the tip of the minute projections to smooth the surface of the photoreceptor, and at the same time, remove ion products deposited between the minute projections to prevent image flow. As a result, development stability is also ensured. Moreover, the toner of the present invention having such an effect can be used even when polished with a cleaning blade, a rubbing roller, or the like.
The surface of the a-Si photosensitive member is not greatly damaged.

Next, an image forming method using the toner of the present invention will be described with reference to FIG. FIG. 3 is the same as the conventional general image forming apparatus except that a rubbing roller (pressing member) 49 is provided.

As a surface protective layer, S of about 0.3 to 1 μm
Around the drum-shaped a-Si photosensitive member 21 having the iC layer, a corona charger 41, an LED head 43 (exposure device), a developing roller 45, a transfer device 47, a rubbing roller 49,
A cleaning blade 51 is provided. After uniform charging of the surface of the photoconductor 21 by the corona charger 41 and formation of an electrostatic latent image by selective image exposure by the LED head 43, the developer 61 is supplied to the surface of the photoconductor 21 by the developing roller 45, and toner is 11 is formed. At this time, the surface of the photoconductor 11 is rubbed by the toner 11 in the developer 61, and the SiC layer on the surface is polished. Further, since the abrasive fine particles 15 are firmly fixed to the toner base particles 13, they do not fall off and do not cause poor development, image defects or the like.

The toner 11 on the surface of the photoreceptor 21 is transferred to a paper 63 (transfer material) by a transfer device 47, and then fixed on the paper 63 by a fixing device (not shown).

In the transfer step, not all the toner 11 on the surface of the photoreceptor 21 is transferred to the paper 63,
Part of the toner 11 (residual toner) remains on the photoconductor 21. The residual toner 11 is pressed against the surface of the photoconductor 21 by the rubbing roller 49 to polish the SiC layer, and the polishing effect of the abrasive particles 15 of the toner 11 increases.

Next, the remaining toner 11 on the photoreceptor 21 is
Is removed from the surface of the photoconductor 21 by the cleaning blade 51.
By the mechanical force applied between the photoconductor 1 and the photoconductor 21,
The surface SiC layer of the photoconductor 21 is polished by the abrasive fine particles 15 of the toner 11.

As the rubbing roller 49, an elastic roller is used. The rubbing roller 49 is pressed against the surface of the photoreceptor 21, and is rotated so that a shear stress is applied to the photoreceptor 21, whereby the photoreceptor 21 is rotated. Is polished and cleaned. Further, by attaching a heater to the inner surface of the photoreceptor 21 and heating it, the effect of preventing image flow can be further improved.

In the above description, an a-Si-based photoreceptor having a SiC layer as a surface layer has been mainly described. However, other types of surface layers or other types of photoreceptors may be used.
The hardness of the abrasive particles may be adjusted according to the hardness of the photoconductor surface layer.

[0064]

According to the present invention, the required charge amount can be arbitrarily set by using a magnetic resin carrier and a magnetic powder carrier in combination, and mixing the abrasive magnetic toner with the carrier to form a developer. To the toner in a stable manner. In addition, the generation of spent is prevented, and as a result, the occurrence of fogging and image defects is prevented, a good image can be formed for a long time, and the replacement of the developer is not required for a long time.

Further, the deterioration of the developer due to agitation is small, the durability stability is good, and a high quality image can be stably obtained over a long period of time. Furthermore, by using two types of magnetic carriers, a resin carrier and a powder carrier, and combining them with an abrasive magnetic toner, the toner is held by electrostatic force and magnetic force, effectively preventing scattering inside the machine even under environmental changes. In addition, it is possible to prevent "carrier pulling" that occurs when a magnetic resin carrier is used.

Further, an excellent polishing effect on the surface of the photosensitive member can be obtained. Therefore, the image forming apparatus can be designed to be compact, and there is no need to incorporate a special system such as a cleaning brush. In particular, a small machine using a small-diameter photosensitive drum, the hardness of the surface layer is large, and the cleaning brush becomes large It is suitable for an a-Si type photoreceptor which easily causes the above.

[0067]

【Example】

(1) Production of a resin carrier According to the method described in JP-A-2-220068, phenol and formalin are condensed in an aqueous medium in the presence of magnetite, and from 85% by weight of magnetite and 15% by weight of phenol resin. Carrier particles (resistance 1
0 ⁶ Ω · cm) was obtained. The carrier particles were coated with 3% by weight of a silicone resin and dried and cured to form a coat layer, thereby producing a magnetic resin carrier. This resin carrier had an average particle diameter of 60 μm, a saturation magnetization of 68 emu / g at 5 KOe, a resistance of 10 ¹⁰ Ω · cm, and a specific gravity of 3.0.

(2) Production of Powder Carrier Using Fe ₂ O ₃ .CuO.ZnO-based ferrite, an average particle size of 60 μm and a saturation magnetization of 68 emu /
g, a non-coated magnetic powder carrier having a resistance of 10 ⁸ Ω · cm was produced.

(3) Production of abrasive magnetic toner Styrene / n-butyl acrylate copolymer (copolymerization ratio 80/20) 83 parts by weight Magnetite (EPT-1000, manufactured by Toda Kogyo KK) 5 parts by weight Carbon Black (MA-100, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) 5 parts by weight Polypropylene wax (Viscol 550P, manufactured by Sanyo Kasei Kogyo Co., Ltd.) 5 parts by weight Charge control agent (Copy Blue PR, manufactured by Hoechst) 2 parts by weight

The toner materials having the above mixing ratios were sufficiently kneaded with a high-speed mixer, pulverized, and classified to obtain toner base particles having an average particle diameter of 10 μm.

Alumina (abrasive) fine particles (average particle size: 0.4 μm) of 5% by weight were added to the toner base particles.
After mixing, the surface modification device (hybridizer,
(Manufactured by Nara Machinery Co., Ltd.) to obtain an abrasive magnetic toner having alumina fine particles fixed on the surface. The alumina fine particles have a Mohs hardness of 9 and a surface having abrasiveness. The abrasive magnetic toner had a saturation magnetization of 4.0 emu / g at 5 KOe.

On the other hand, a toner for comparison (a toner without an abrasive) was produced without using magnetite, fixing the magnetic alumina fine particles, and using the toner base particles as they were.

(4) Preparation of Developer The above carrier and toner are mixed at the following ratio,
The following developers were prepared. Example 1: Magnetic resin carrier 20 wt% + magnetic powder carrier 75 wt% + abrasive magnetic toner 5 wt%

Comparative Example 1: Magnetic resin carrier 20 wt% +
Magnetic powder carrier 75wt% + abrasiveless toner 5wt
Comparative Example 2: 95% by weight of magnetic powder carrier + 5% by weight of toner without abrasive

(5) Evaluation of Spent 30 points were measured using the Kyocera LED printer FS-1500.
Ten thousand continuous prints were made, and the spent amount for each developer was measured and calculated with a total carbon meter, and is shown in FIG. Further, the image quality and print characteristics after the initial printing of 100,000 sheets and after printing of 200,000 sheets were evaluated under the environmental conditions of 35 ° C. and 85% RH based on the following criteria.
It was shown to.

(I) Carrier pulling ：: Not generated at all △: Slightly generated ×: Image defect occurs

(Ii) Fog ：: No fog occurs Δ: Slight fog ×: Fog is clearly observed

(Iii) Scattering inside the machine ○: No dirt is seen in the printer at all △: Slight dirt is seen ×: Dirt is severe and the back of the paper is dirty

[0079]

[Table 1]

(6) Evaluation of Image Deletion Using the developer of Example 1 and Comparative Example 1, 300,000 sheets of continuous printing were performed using the apparatus shown in FIG. The flow was evaluated, and the thickness of the surface SiC layer after printing 300,000 sheets was measured by XPS. The results are shown in Table 2.

As the photoreceptor, a light absorbing layer (Si: Ge: H, 0.2 to 5 μm) and a carrier injection blocking layer (Si: H: B: O, 0.2 to 4 μm) are formed on a conductive substrate. ), Carrier excitation / transport layer (Si: H, 15 to 30 μm), S
The thickness of the SiC surface protective layer was unified to 5,000 ° using an a-Si based photoreceptor in which an iC surface protective layer was sequentially laminated.

The surface of the a-Si photosensitive member was scanned with a scanning electron microscope (S) both at the initial stage and after printing 300,000 sheets.
Observation at 5,000 times using EM) revealed that after printing 300,000 sheets compared to the initial stage, the number of cones was reduced and the surface was smoothed.

(I) Black spots ：: Black spots are not seen at all △: Black spots are seen a little ×: Many black spots

(Ii) Image deletion ：: No image deletion occurs Δ: Slight image deletion ×: Image deletion occurs over the entire surface

[0085]

[Table 2]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a model sectional view showing an embodiment of a toner of the present invention.
is there. FIG. 2 is a diagram illustrating an example of a layer configuration of an a-Si photoconductor.
It is sectional drawing. FIG. 3 shows an example of an image forming apparatus for carrying out the present invention.
FIG. FIG. 4 is a graph showing the relationship between the number of prints and the amount of spent.
It is. DESCRIPTION OF SYMBOLS 11 Toner 13 Toner base particle 15 Fine abrasive particles 21 Photoconductor 23 Conductive substrate 25 Light absorption layer 27 Carrier injection blocking layer 29 Carrier excitation / transport layer 31 Surface protection layer 41 Corona charger 43 LED head 45 Development Roller 47 Transfer device 49 Rubbing roller 51 Cleaning blade 61 Developer 63 Paper

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/08 507L (72) Inventor Noriaki Sakamoto 704, Matabe, Noshino, Noshina, Tamaki-cho, Mie Prefecture Mie Prefecture 19 Mie Tamaki Factory, Kyocera Corporation (56) References JP-A-1-285954 (JP, A) JP-A-60-229037 (JP, A) JP-A-61-29856 (JP, A) JP-A-63-244054 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 9/08 G03G 9/083 G03G 9/107 G03G 9/113 G03G 5/08 105 G03G 15/08 507

Claims (3)

(57) [Claims] (A) a magnetic resin carrier in which magnetic fine particles are dispersed in a binder resin; (b) a magnetic powder carrier substantially consisting of magnetic particles themselves; and (c) abrasive particles fixed on the surface. A developer for an electrostatic latent image, comprising: an abrasive magnetic toner; 2. The developer for an electrostatic latent image according to claim 1, wherein the abrasive magnetic toner has a saturation magnetization of 2 to 20 emu / g at 5 Kl Oersted. 3. An electrostatic latent image is formed on an a-Si photosensitive member having an amorphous silicon (a-Si) photosensitive layer while being conveyed. A magnetic resin carrier in which magnetic fine particles are dispersed in a binder resin; (b) a magnetic powder carrier substantially consisting of magnetic particles themselves; and (c) an abrasive magnetic toner having abrasive fine particles fixed on the surface. After developing with an electrostatic latent image developer, and then transferring the abrasive magnetic toner that forms a toner image on the surface of the photoreceptor, partially untransferred abrasive magnetism remaining on the conveyed photoreceptor An image forming method, wherein a pressing member is pressed against a toner, and the surface of the a-Si photosensitive member is polished by the polishing force of the abrasive magnetic toner and the pressing force of the pressing member.