JP2000284509A - Image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device which suppresses the adverse effect of image flowing and can form a stable high-grade image. SOLUTION: In the image forming device in which developing bias is applied to a developer carrier to make a latent image visible by development, an image carrier 1 has a photosensitive layer on an electrically conductive substrate and the photosensitive layer contains at least one polycarbonate resin (I) having a viscosity average molecular weight of <=1.5×104 and at least one polycarbonate resin (II) having a viscosity average molecular weight of >1.5×104. The polycarbonate resin (I) is contained by 30-95 wt.% of the total amount of the polycarbonate resins (I) and (II). The amount of a developer applied to a developing region on the developer carrier 1 after regulation with a regulating member 9 is <=1.5 mg/cm2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and a process cartridge used for a copying machine, a page printer, a facsimile, and the like.

[0002]

2. Description of the Related Art An electrophotographic image forming apparatus of an electrophotographic type such as a laser beam printer or a copying machine uses a powdery developer, for example, a toner.

[0003] The toner is accommodated in a developing container, transported to a toner carrier by toner transport means, and held on the toner carrier. Then, a predetermined charge is applied by a toner layer thickness regulating member, for example, a doctor blade, and moves to an electrostatic latent image forming section on the image carrier that carries the image, thereby visualizing the electrostatic latent image on the photoconductor. Thereafter, the visible image is transferred to a transfer material such as paper by a transfer unit, and fixed by a fixing device. The toner remaining on the image carrier without being transferred to the transfer material is peeled off from the image carrier by a cleaning device in contact with the image carrier and sent to a cleaning container.
Thus, a series of image forming processes is completed, and the user can obtain a desired image.

As one of the developing methods, a jumping developing method for developing a latent image on an image carrier while holding a developer carrier of the image forming apparatus in non-contact with the image carrier is known. I have. As an example of an image forming apparatus employing the jumping development method, an image forming apparatus shown in FIG. 1 will be described.

In the image forming apparatus shown in FIG. 1, the toner contained in the developing container 3 is held on a developer carrier, for example, a developing sleeve 10, and the developing sleeve 10 rotates in the direction of arrow b in FIG. The held toner 8 is conveyed toward a development area facing the photoconductor 1 as an image carrier. During the transportation, the toner 8 is regulated by the doctor blade 9 in contact with the developing sleeve 10 and is applied on the developing sleeve 10 in a thin layer. In the developing area, the developing sleeve 10 and the photoconductor 1 are held with a gap of 50 to 500 μm, and the developing power is applied to the developing sleeve 10 by the bias power supply 12 so that the developing bias is superimposed on the direct current. The toner 8 applied in a thin layer on the sleeve 10 flies onto the electrostatic latent image on the photoreceptor 1,
Upon attachment, the latent image is visualized as a toner image.

[0006]

There is a problem of image deletion in a high-temperature and high-humidity environment. "Image deletion" means that a low-resistance substance adheres to the photosensitive drum, and charges in a charged portion on the image carrier flow into the latent image portion, and an image is lost. Although this image deletion may occur due to dew condensation on the surface of the photosensitive drum, talc or OHT (Over Head) contained in the transfer material is often used.
d Thin film) occurs because the surfactant contained in the thin film adheres to the surface of the photosensitive drum.

[0007] Talc, which is often contained in general transfer materials, is composed of an oxide generated by ozone generated from a charging device and moisture due to high humidity, and a low-resistance substance is formed on the image carrier. Ozone product is generated, causing image deletion.

As described above, the above problem is easily affected by the transfer material, and it has been difficult for conventional image forming apparatuses to solve all of high resolution and high definition images, durability stability and image deletion.

Further, the surface of the photosensitive drum is easily scraped,
Proposals have also been made so that good images can be formed for a long period of time (Japanese Patent Publication No. 4-78984, and Japanese Patent Application Laid-Open No. 1-20).
6348). However, the problem of preventing image deletion cannot be sufficiently solved only by designing the material of the photosensitive drum.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of suppressing an adverse effect of image deletion and forming a stable high-quality image.

It is another object of the present invention to provide an image forming apparatus capable of stably forming high-quality images while improving the image density while suppressing the adverse effects such as image deletion and passing of external additives. That is.

It is a further object of the present invention to provide a process cartridge which can suppress adverse effects such as image deletion and slip-through of external additives, stably form high-quality images, and which does not require maintenance. It is.

[0013]

The above object is achieved by an image forming apparatus and a process cartridge according to the present invention.

That is, the present invention provides at least an image carrier, a developer, a developer carrier for carrying the developer and transporting the developer to a development area, and contacting the developer carrier with the developer carrier. A regulating member for regulating the amount of developer applied, wherein the developer carrying member carries the developer and conveys the developer to the developing area, and forms an electrostatic latent image formed on the image carrying member. In an image forming apparatus for developing and visualizing by applying a developing bias to the developer carrier, the image carrier has a photosensitive layer on a conductive substrate, and the photosensitive layer has a size of 1.5 × 10 ⁴ or less. It contains at least one kind of polycarbonate resin (I) having a viscosity average molecular weight and at least one kind of polycarbonate resin (II) having a viscosity average molecular weight of more than 1.5 × 10 ⁴ , wherein the polycarbonate resin (I) is a polycarbonate resin. Resin (I) (II) in a ratio of 30% by weight to 95% by weight based on the total amount of the developer. The present invention relates to an image forming apparatus characterized in that the amount is not more than 0.5 mg / cm ² .

Further, the present invention provides at least an image carrier, a developer, a developer carrier for carrying the developer and transporting the developer to a development area, and the developer abutting on the developer carrier. A regulating member for regulating the amount of application of the developer, wherein the developer carrier carries the developer and conveys the developer to the developing area, and develops the electrostatic latent image formed on the image carrier into the developing device. In a process cartridge integrated with means for applying a developing bias to a developer carrier to perform development and visualization, and detachably attached to the image forming apparatus main body, the image carrier comprises a photosensitive layer on a conductive substrate. And the photosensitive layer has a thickness of 1.5
And at least one of a polycarbonate resin (I) having a viscosity-average molecular weight of × 10 ⁴ or less, and contains at least one kind of polycarbonate resin (II) having a 1.5 × 10 ⁴ larger viscosity average molecular weight, the polycarbonate resin ( I) is contained at a ratio of 30% by weight to 95% by weight based on the total amount of the polycarbonate resins (I) and (II).
The present invention relates to a process cartridge, wherein an amount of a developer applied to a development area after being regulated by the regulating member is 1.5 mg / cm ² or less.

In the structure of the present invention, even if talc contained in the transfer material, which is a main cause of image deletion, adheres to the surface of the photosensitive drum, it is possible to determine whether the molecular weight of the polycarbonate resin as the material of the surface layer of the photosensitive drum is high or low. Mix,
By reducing the amount of applied toner on the developing sleeve, the scraping of the surface layer of the photosensitive drum is promoted, and talc is scraped off together with the surface layer of the photosensitive drum, so that image deletion can be prevented.

Further, when inorganic fine powder is externally added to the toner, the externally added fine powder particles serve as an abrasive, further promoting the shaving of the photosensitive drum surface layer, and greatly preventing image flow. Bring effect. It also contributes to the prevention of the phenomenon that the toner is fused in the circumferential direction on the surface of the photosensitive drum (filming) and the phenomenon that the external additive slips through the cleaning blade and causes a cleaning failure.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing an example of an LBP using an electrophotographic process to which the present invention is applied. Although FIG. 1 is used in the description of the related art, since the image forming process itself is the same as the related art, this drawing is used.

Reference numeral 1 denotes an electrophotographic photosensitive member, for example, a photosensitive drum, which is composed of an OPC photosensitive member. The rotation speed of the photosensitive drum, that is, the process speed is 100 mm / sec.
At c, it rotates in the a direction. The charging roller 2 uniformly charges the photosensitive drum 1. Next, laser scanner 4
Is exposed according to the image signal. The laser scanner 4 scans the blinking of the semiconductor laser with a polygon scanner, and forms an image on the photosensitive drum 1 by an optical system. This creates an electrostatic latent image. The created electrostatic latent image is developed in the developing container 3. For development, a developing method such as jumping development is used, and in a place where recording is performed, a laser is turned on, image exposure that eliminates the charge of the latent image, and reversal development that attaches toner to the less charged one is used. .

The developed image is transferred to a transfer material 102. The transfer material 102 is contained in a cassette 100 and is fed one by one by a paper feed roller (not shown). When a print signal is sent from the host, paper is fed by a paper feed roller, and the transfer roller 13 transfers a toner image onto a transfer material. The transfer roller 13 is a conductive elastic body, and is electrostatically transferred by a bias electric field at a nip formed by the photosensitive drum 1 and the transfer roller 13.

The transfer material 102 onto which the image has been transferred is fixed by the fixing device 101. On the other hand, the transfer residual toner is cleaned by the cleaning blade 7.

On the developing sleeve, the amount of toner applied to the developing area after the regulation by the developing blade is reduced by 1.5.
mg / cm ² or less, the charge of the toner is reliably and stably provided between the developing sleeve and the developing blade, and the unstable toner remaining after the transfer is reduced.
Reduce the amount of toner that also works as a lubricant at the cleaning blade contact part, and promote the shaving of the photosensitive drum surface layer,
The talc is scraped off along with the surface layer of the photosensitive drum, so that image deletion can be prevented.

FIG. 2 is a diagram showing in detail the photosensitive drum 1 used in the present invention.

The photosensitive drum 1 comprises a substrate 21, a charge generation layer 2
2 and the charge transport layer 23. As the base 21, a cylindrical cylinder or a film of metal such as aluminum or stainless steel, paper, plastic, or the like is used.

The charge generation layer 22 contains 0.5% of the charge generation pigment.
It is well dispersed with a binder resin and a solvent in an amount of up to 4 times by a method such as a homogenizer, an ultrasonic wave, a ball mill, a vibrating ball mill, a sand mill, an attritor, and a roll mill, and is coated and dried. Its thickness is 0.1 ~
It is about 1 μm.

The charge transporting layer 23 is applied on the charge generating layer by dissolving a blend composition of the charge transporting substance and the aforementioned polycarbonate resins (I) and (II) in a solvent. The mixing ratio of the charge transporting substance and the polycarbonate resin blend composition is about 2: 1 to 1: 2. Examples of the solvent include ketones such as cyclohexanone, esters such as methyl acetate and ethyl acetate, ethers such as THF, and chlorinated hydrocarbons such as chlorobenzene, chloroform and carbon tetrachloride.

In general, the strength (abrasion resistance and hardness) of a resin increases with an increase in molecular weight. However, when the molecular weight further exceeds a certain level, even if the molecular weight increases, the strength no longer increases and shows a constant value. On the other hand, when the molecular weight decreases, the strength gradually decreases, and when the molecular weight further decreases, the strength sharply decreases.

In the case of a polycarbonate resin, the molecular weight at which the strength rapidly decreases is 1.5 × 10 ^{4 to} 2.0 × 10 ^4.
Therefore, by containing a resin having a lower molecular weight to some extent, appropriate abrasion can be imparted.

Since the photosensitive layer containing such a polycarbonate resin has a suitable abrasion property, low-resistance deposits such as ozone products are easily removed due to minute abrasion on the surface of the photosensitive layer, and the surface is cleaned. , It is difficult to cause image quality deterioration. However, the surface that does not contain low molecular weight components tends to be weak against mechanical external forces such as rubbing, and the parts that wear a lot and the parts that wear only a small amount when image formation is repeated are repeated. In some cases, low resistance deposits may not be completely removed in a portion where a small amount of wear occurs, resulting in a slightly disadvantageous direction for image deletion.

The composition ratio of the blend composition of the polycarbonate resins (I) and (II) in the present invention is such that the polycarbonate (I) having a viscosity average molecular weight of 1.5 × 10 ⁴ or less is used.
Is preferably 30% to 95% by weight based on the aforementioned blend composition.

If the content of the polycarbonate (I) is less than 30% by weight, a suitable abrasion cannot be provided, and the above-mentioned effects cannot be obtained. On the other hand, if it exceeds 95% by weight, there are problems such as excessive wear and a decrease in viscosity. The molecular weight of the polycarbonate (I) is desirably 1.5 × 10 ⁴ or less, at which a sharp change in strength occurs, as described above.

The measurement of the viscosity average molecular weight of the polycarbonate resin is performed as follows.

0.5 g of a sample is precisely weighed and dissolved in 100 ml of methylene chloride, and the specific viscosity at 25 ° C. is measured using an Ubbelohde viscometer. The intrinsic viscosity is determined from this specific viscosity, and the viscosity average molecular weight is calculated by the Mark-Houwink viscosity formula.

The viscosity average molecular weight of the polycarbonate resin (I) is more preferably 1 × 10 ⁴ or less, and 4 × 10 ³ to
A range of 1 × 10 ⁴ is particularly preferred. The viscosity average molecular weight of the polycarbonate resin (II) is particularly preferably 8 × 10 ⁴ or less.

A preferred polycarbonate resin used in the present invention is a resin containing a linear polymer containing one or more kinds of repeating units represented by the following general formula (A).

[0036]

[Outside 1] (In the formula, R ₁ and R ₂ are each a hydrogen atom, an alkyl group or an aromatic group. Further, R ₁ and R ₂ may form a cyclic structure together with the carbon atom bonded thereto. X _1, X _2,
X ₃ and X ₄ each represent a hydrogen atom, a halogen atom, an alkyl group or an aryl group. )

As the charge transporting substance, triarylamine compounds, hydrazone compounds, stilbene compounds,
Examples include pyrazoline-based compounds, oxazole-based compounds, triallylmethane-based compounds, and thiazole-based compounds.

Next, FIG. 3 shows a cross-sectional view of an example of a developing device for reducing the amount of toner coating at the developing position of the developing sleeve to 1.5 mg / cm ² or less.

An elastic developing blade 9 serving as a developer regulating member is brought into contact with the developing sleeve 10. The developing sleeve 10 is a nonmagnetic aluminum sleeve having a diameter of 16 mm and a surface having a surface roughness Ra of 1.0 μm coated with a resin layer containing conductive particles.

The developing blade 9 has a rubber hardness of 4 according to JISA.
The silicone rubber at 0 ° is brought into contact with the developing sleeve 10 at a contact force P (contact load gf / cm per cm in the longitudinal direction of the sleeve) of 35 gf / cm.
Installed in the developer container. The contact width (nip) between the developing sleeve 10 and the developing blade 9 is 1.0 mm, and the distance from the most upstream position (upstream in the rotation direction of the developing sleeve 10) to the free end of the developing blade 9 is 1.7 mm. .

A magnet roll 11 is fixedly arranged in the developing sleeve 10. The one-component magnetic toner 8 is contained in the developing container 3, is sent to the vicinity of the developing sleeve 10 by stirring, and is supplied to the developing sleeve 10 by the action of a magnetic field formed by the magnet roll 11, and is conveyed with the rotation of the developing sleeve 10. Is done. Thereafter, the toner is conveyed to the developing area under the application of a tribo at the contact portion with the developing blade 9 and the regulation of the layer thickness.

An alternating voltage obtained by superimposing a direct current and an alternating current is applied to the developing sleeve 10 by a power supply 12 to form a developing electric field between the developing sleeve 10 and the photosensitive drum 1, and the electrostatic latent image is developed in accordance with the electric field. DC voltage: Vdc = −
At 500 V, AC: square wave Vpp = 1600 V, f = 1
A developing bias superimposed with 800 Hz is applied. The developing sleeve 10 and the photosensitive drum 1 face each other with a gap of 300 μm at the closest position. Photosensitive drum 1 is uniformly charged to charging potential Vd = -700 V, part thereof becomes V ₁ = -150 V is exposed by a laser in accordance with image signals. Reversely develops the V ₁ parts of negatively chargeable toner.

Further, in order to promote the scraping of the surface of the photosensitive drum and to more effectively prevent the image deletion, it is effective to externally add fine powder particles acting as an abrasive to toner as a developer. It is.

Among the fine powder particles as external additives, metal oxidation
The material particles have much higher hardness than the toner 8.
The cleaning blade 7 of the cleaning device
In the contact portion of the drum 1, the metal oxide particles
And promotes scraping of the surface layer of the photosensitive drum 1. Ma
In addition, as metal oxide particles, strontium titanate is
Because it is a strongly positive substance, it can be used in image forming equipment for reversal development.
Is easy to develop on a white background. In particular, the developing sleeve
1.5 mg / cm of the coating amount of the toner 8 on ^TwoLess than
The developing sleeve 10 and the developing blade
The charging of the toner 8 at the contact portion 9 is reliably performed.
Therefore, strontium titanate has a high positive charge
As a result, the developing power on the white background increases.

Since only a small amount of reversible toner adheres to the white background, the amount of talc directly adhering to the surface of the photosensitive drum 1 is larger than that in the printing area, and the image is liable to flow. For this reason, by using a strong positive material as in this embodiment, it is possible to develop on a white background and scrape talc adhered to the surface of the photosensitive drum 1, thereby preventing image deletion. Further, since an image to be printed usually has many characters, the area of a white background portion in one transfer material 102 is overwhelmingly large. If the material is positive, it is developed on the white background to promote the scraping of the surface layer of the photosensitive drum 1,
The surface of the photosensitive drum 1 can be uniformly scraped off, and no image unevenness occurs.

Further, in the case of the negative toner, the negative charge of the toner is quickly performed by contact with the positive fine powder particles, and the toner is stabilized. It also has the effect of stabilizing the concentration.

The same effect as described above can be obtained with other strongly positive materials such as zinc oxide.

If the particle size of the fine powder particles is too small,
The fine powder particles adhering to the surface of the photosensitive drum 1 after the transfer are not scraped off by the cleaning blade 7 and slip through, so that a cleaning defect that causes a thin vertical stripe on a white background image is likely to occur. In order to prevent the occurrence of this cleaning failure and also to prevent the image deletion, the particle size should be 5 × 1.
It is desirable that the thickness be 0 ^-3 μm to ³ μm.

The particle diameter of the fine powder particles was determined by randomly extracting 100 to 200 particles from a photograph taken with an electron microscope, measuring the major diameter of each particle using a measuring instrument such as a caliper, and averaging the number averaged number. Value.

Further, it has been found that when the content of the fine powder particles is large, a phenomenon that the toner is fused along the circumferential direction of the photosensitive drum 1 (hereinafter referred to as filming) occurs. If the content is large, the fine powder particles aggregate and damage the surface of the photosensitive drum, and the toner adheres to the surface. As a result of the study, it was found that the content of the fine powder particles should be 0.1% by weight to 5.0% by weight in order to prevent the filming and to prevent the occurrence of the image deletion.

As preferred fine powder particles, silica, strontium titanate, cerium oxide, aluminum oxide, zinc oxide and the like are used.

The toner 8 preferably has an MI of 3 to 30 and a weight average particle size of 3.5 to 7.0 μm.

MI is a melt index and is a flow test method for thermoplastics according to Japanese Industrial Standard JIS K72.
The measurement is performed by the manual cutting method using the apparatus described in No. 10 under the following measurement conditions. At this time, the measured value is converted into a 10-minute value.

Measurement temperature: 125 ° C. Load: 10 kg Sample filling amount: 5 to 10 g

Example 1 (Photosensitive Drum) The photosensitive drum shown in FIG. 2 was used.

The base 21 is an aluminum cylinder having a diameter of 30 mm. The charge generation layer 22 was formed as follows. A dispersion composed of 4 parts (by weight) of oxytitanium phthalocyanine as a charge generating pigment, 2 parts of polyvinyl butyral (trade name: Eslec BM2, manufactured by Sekisui Chemical) and 60 parts of cyclohexanone is applied to the surface of an aluminum cylinder by a dipping method, and dried. Thus, a charge generation layer having a thickness of 0.3 μm was formed.

The charge transport layer 23 was formed as follows. As the charge transport material, 9 parts of an amine compound represented by the following structural formula, 9.5 parts of a polycarbonate resin, 2 parts of polytetrafluoroethylene (trade name: Lubron L-2, manufactured by Daikin, particle size: 0.5 μm), mono Chlorobenzene 5
A coating composed of 0 parts and 50 parts of dichloromethane was applied on the charge generating layer by an immersion method and dried to form a charge transporting layer having a thickness of 20 μm.

[0058]

[Outside 2]

The following two kinds of polycarbonate resins were used.

Polycarbonate resin (I): a resin represented by the general formula (A), wherein X ₁ = CH ₃ , X ₂ = H, X ₃ =
CH ₃ , X ₄ = H, R ₁ = CH ₃ and R ₂ = CH ₃ ;
Polycarbonate resin (II) having a viscosity average molecular weight of 5 × 10 ³ , a resin represented by the general formula (A), wherein X ₁ = CH ₃ , X ₂ = H, X ₃ = CH ₃ , X ₄ =
H, R ₁ = CH ₃ and R ₂ = CH ₃ , the viscosity average molecular weight is 2 × 10 ⁴ , the content of the polycarbonate resin (I) is 40 parts by weight when the total amount of the polycarbonate resin is 100 parts by weight,
That is, it is 40% by weight.

(Developer) As the toner 8, a negatively chargeable magnetic one-component toner is used. Styrene n- as binder resin
100 parts by weight of a butyl acrylate copolymer, 80 parts by weight of magnetic particles, 2 parts by weight of a monoazo iron complex negative charge control agent, and 3 parts by weight of low molecular weight polypropylene as a wax, a biaxial extruder heated to 140 ° C. The kneaded material that has been melted and kneaded in the above is coarsely pulverized with a hammer mill, the coarsely pulverized material is finely pulverized with a jet mill, and the obtained finely pulverized material is classified by wind power to obtain a classified powder having a weight average particle size of 5.0 μm I got Henschel mixer, a mixer having 1.0 part by weight of hydrophobic silica fine powder and high-speed stirring blades in a classified product having an average particle size of 5.0 μm; “Henschel” manufactured by Mitsui Miike Kakoki Co., Ltd.
l Mixer "(Trademark), manuf
acted byMitsumiimikekako
Mix with uki Kabushiki Kaisha,
A developer was obtained. The fixing property index MI (melt index) is 20.

The developing blade 9 is placed in a pre-heated mold.
A 60 μm-thick stainless steel coated with a silicone primer is placed, and LTV silicone rubber (LSR SE6744; manufactured by Dow Corning Toray) is placed on the stainless steel.
Was injected with a LIM injection molding machine, removed from the mold after 5 minutes at 150 ° C., heat-treated at 200 ° C. for 4 hours, and integrally molded to obtain a silicone rubber blade having a rubber hardness of 40 °.

Using the photosensitive drum, the developer and the developing blade described above, image deletion in a high-temperature and high-humidity (30 ° C., 80% RH) environment was evaluated by the apparatus shown in FIGS. .

As the transferred transfer material, a paper containing talc was used, and a horizontal line pattern having a printing rate of 4% was used as an image sample when the paper was passed.

The evaluation was performed when the photosensitive drum 1 according to the present embodiment has a coating amount of the toner 8 on the developing sleeve 10 which is a conventional developing device is 2.5 mg / cm ² , and the present invention according to the present embodiment. In the case of 1.0 mg / cm ² obtained from the developing device, the evaluation was made based on the degree of streaking in the character portion in each of the 4% printed alphabet and kanji patterns. 1000 in Table 1
The evaluation results when zero sheets are passed are shown.

[0066]

[Table 1]

As shown in Table 1, when the coating amount of the toner 8 on the developing sleeve 10 was large, the image deletion occurred from 3000 sheets. The reason is as follows. When the amount of toner coating on the developing sleeve 10 is large, the amount of toner developed on the photosensitive drum 1 increases. Since the toner 8 includes a large amount of the toner 8 having no appropriate charge, the toner 8 that does not fly to the transfer material 102 during transfer and remains on the photosensitive drum 1 increases. This much transfer residual toner will be separated by the cleaning blade 7 in the cleaning device. In this case, a lot of toner is interposed in the contact portion between the cleaning blade 7 and the photosensitive drum 1, and a part of the toner acts as a lubricant for the cleaning blade 7, so that the action of scraping the photosensitive drum 1 is reduced, and This is due to the fact that talc adhered to one surface and image deletion occurred. When the coating amount on the developing sleeve 10 was 2.5 mg / cm ² , the shaving amount of the surface layer of the photosensitive drum 1 was 0.8 μm per 1,000 sheets.

On the other hand, when the coating amount on the developing sleeve 10 is 1.0 mg / cm ² , although image deletion occurs from 6000 sheets, this is a practically acceptable level.
There was no further deterioration up to 000 sheets. At this time, the abrasion amount of the surface layer of the photosensitive drum 1 is 1.1 μm per 1000 sheets, the amount of toner interposed in the contact portion between the cleaning blade 7 and the photosensitive drum 1 is reduced, and the photosensitive amount corresponding to the action of preventing image flow is reduced. It was confirmed that the shaving amount of the drum 1 could be obtained.

Further, in the above evaluation, the occurrence level of the image flow with respect to the coating amount of the toner 8 on the developing sleeve 10 on 10,000 sheets was evaluated, and the results are as shown in Table 2.

[0070]

[Table 2]

As can be seen from Table 2, the reason why the effect of suppressing the image deletion and obtaining the effect to the extent that there is no practical problem is obtained is that the coating amount of the toner 8 on the developing sleeve 10 is 1.5 mg /
cm ² or less.

Further, in the configuration of the present invention, normal temperature and normal humidity (25 ° C., 60% RH), low temperature and low humidity (15 ° C., 10% RH)
H), as a result of performing a durability test in a high-temperature and high-humidity (30 ° C., 80% RH) environment, there is no adverse effect associated with the configuration of the present invention, and a high-quality image can be stably obtained in any environment. It was confirmed.

As described above, a photosensitive drum containing a polycarbonate resin having a high average molecular weight and a low average molecular weight is used, and the amount of applied toner in the developing area after the regulation by the developing blade on the developing sleeve is 1%. 0.5mg
/ Cm ² or less, promotes the scraping of the photosensitive drum surface layer, talc adhering to the photosensitive drum surface is scraped off together with the photosensitive drum surface layer, preventing image deletion and obtaining a stable image. it can.

Embodiment 2 In this embodiment, fine powder particles are externally added to the classified toner of Embodiment 1, and the coating amount of the toner on the developing sleeve is 1.5 mg / cm ² or less.

More specifically, strontium titanate having a primary particle diameter of 1.8 μm and 2.0% by weight as metal oxide particles was added to the classified product of the toner 8 used in the first embodiment. It was mixed and externally added with a Henschel mixer.

Using the toner 8 as described above, the coating amount of the toner 8 on the developing sleeve 10 is set to 1.0 mg / cm ²
The evaluation of image deletion for the presence or absence of strontium titanate as fine powder particles was performed. Other image forming conditions are the same as in the first embodiment.

Table 3 shows the evaluation results.

[0078]

[Table 3]

As described in the first embodiment, by reducing the coating amount of the toner 8 on the developing sleeve 10,
The amount of scraping of the surface layer of the photosensitive drum 1 was promoted, and it was possible to reach a level of practically no problem up to 10,000 sheets.
Further, by externally adding strontium titanate, which is fine powder particles, to the toner, the surface layer of the photosensitive drum could be more uniformly shaved, and as shown in Table 3, no image deletion occurred even after passing through 10,000 sheets. At this time, the abrasion amount of the surface layer of the photosensitive drum was 1.5 μm per 1,000 sheets, and 1.1 μm was obtained without fine powder particles.

As described above, by using fine powder particles externally added to the toner 8 in the structure of the present invention, the externally added fine powder particles act as an abrasive, and the surface layer of the photosensitive drum 1 is formed. It promotes shaving and has a great effect on preventing image deletion. In addition, external addition of fine powder particles can both prevent filming in which toner fuses in the circumferential direction on the surface of the photosensitive drum 1 and prevent the external additive from slipping through the cleaning blade 7 and causing a phenomenon of poor cleaning. Can also.

Embodiment 3 This embodiment relates to a process cartridge provided with a photosensitive drum and a developing device.

FIG. 4 is a sectional view of the process cartridge of this embodiment.

The photosensitive drum 1 used in Example 1, a charging device 2 for charging the surface of the photosensitive drum 1, and the photosensitive drum 1
A developing device 3 for visualizing the latent image on the surface and a cleaning device 14 for cleaning the toner 8 remaining on the photosensitive drum 1 without being transferred after the transfer are integrated, and are detachable from the image forming apparatus main body. . The image forming process conditions are the same as in the first embodiment.

In general, the surface of the photosensitive drum 1 is deteriorated due to the discharge caused by the charging of the charging device 2, and the photosensitive drum 1 is easily scraped. Therefore, the new photosensitive drum 1 is hard to be scraped at the beginning of use. For example, in Example 1, X ₁ = CH ₃ , X ₂ =
H, X ₃ = CH ₃ , X ₄ = H, R ₁ = CH ₃ and R ₂ = CH
₃ polycarbonate resin (viscosity average molecular weight 4 × 10 ⁴ )
The transition of the shaving amount of the photosensitive drum 1 for every 1000 sheets using the method shown in FIG. The amount of shaving up to 1000 sheets from the initial stage is small, and thereafter it is stable. Therefore, in the early stage of use when the amount of scraping of the surface layer of the photosensitive drum 1 is small, image deletion easily occurs.

Therefore, the coating amount of the toner 8 on the developing sleeve 10 as described in the second embodiment is set to 1.5 mg / cm ²
In the following, by adding a positive material having high hardness to the toner 8, the shaving amount of the surface layer of the photosensitive drum 1 can be stabilized.

This is because the external additive used as the polishing agent reduces the coating amount of the toner 8 on the developing sleeve 10 by 1.5.
When a thin layer having a thickness of less than mg / cm ² is used, a large amount of charge is imparted to the toner, and the developing power is increased. This is because they cut as much as they did.

For example, FIG. 6 shows the amount of strontium titanate developed on the photosensitive drum every 1000 sheets when the strontium titanate externally added toner used in Example 2 was passed at a printing rate of 4%. Indicated. Positive materials, such as strontium titanate, are likely to be developed in large quantities at the beginning because they tend to fly to white areas, and thereafter the amount of development is reduced because the amount of strontium titanate contained in the toner is reduced. To go.

As described above, a large amount of abrasive is used in the initial stage when the photosensitive drum 1 is difficult to be scraped, and when the photosensitive drum 1 is easily scraped, the amount of the abrasive is suppressed to thereby reduce the sharpness of the photosensitive drum 1. That is, the amount can be stabilized.

In this embodiment, the amount of scraping of the photosensitive drum 1 was confirmed using the toner 8 to which strontium titanate was added at 1.5% by weight. The result is the solid line in FIG.
Approximately, the scraping amount of the photosensitive drum 1 was stable until the service life. In addition, image deletion was evaluated, and it was confirmed that no occurrence occurred up to 10,000 sheets.

Therefore, in order to obtain the above effects, a combination of a new photosensitive drum and a new developing device is required. Therefore, by providing a process cartridge in which at least the photosensitive drum and the developing device are integrated as in this embodiment, it is possible to provide the user with a form in which the amount of shaving on the photosensitive drum surface is optimized.

Example 4 An image deletion evaluation test was performed in the same manner as in Example 1 except that the following polycarbonate resins (I) and (II) were used.

Polycarbonate resin (I): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ and R ₂ form a cyclohexane ring together with the bonding carbon atoms, and have a viscosity average molecular weight of 4 × 10 ³ .

Polycarbonate resin (II): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ and R ₂ form a cyclohexane ring together with the bonding carbon atoms, and have a viscosity average molecular weight of 1.6 × 10 ⁴ .

The results are shown in the following table.

[0095]

[Table 4]

Example 5 An image deletion evaluation test was performed in the same manner as in Example 1 except that the following polycarbonate resins (I) and (II) were used.

Polycarbonate resin (I): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ = CH ₃ , and R ₂ = C ₆ H ₆ ,
The viscosity average molecular weight is 1 × 10 ⁴ .

Polycarbonate resin (II): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ = CH ₃ , and R ₂ = C ₆ H ₆ ,
The viscosity average molecular weight is 8 × 10 ⁴ .

The results are shown in the following table.

[0100]

[Table 5]

Example 6 An image deletion evaluation test was performed in the same manner as in Example 1 except that the following polycarbonate resins (I) and (II) were used.

Polycarbonate resin (I): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ = CH ₃ , and R ₂ = CH ₃ , and the viscosity average molecular weight is 7 × 10 ³ .

Polycarbonate resin (II): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ = CH ₃ , and R ₂ = CH ₃ , and the viscosity average molecular weight is 2 × 10 ⁴ . The polycarbonate resin (I) was 30% by weight, and (II) was 70% by weight.

The results are shown in the following table.

[0105]

[Table 6]

Example 7 An image deletion evaluation test was performed in the same manner as in Example 1 except that the following polycarbonate resins (I) and (II) were used.

Polycarbonate resin (I): a resin represented by the general formula (A), wherein X ₁ = CH ₃ , X ₂ = H, X ₃ =
CH ₃ , X ₄ = H, R ₁ = CH ₃ , and R ₂ = CH ₃ , and the viscosity average molecular weight is 5 × 10 ³ .

Polycarbonate resin (II): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ and R ₂ form a cyclohexane ring in cooperation with the bonding carbon atom, and have a viscosity average molecular weight of 2 × 10 ⁴ .

The results are shown in the following table.

[0110]

[Table 7]

Example 8 In Example 1, the following polycarbonate resins (I) and (II) were used, and the content of (I) was 6
An image deletion evaluation test was performed in the same manner as in Example 1 except that the amount was set to 0% by weight.

Polycarbonate resin (I): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ and R ₂ form a cyclohexane ring in cooperation with the bonding carbon atom, and have a viscosity average molecular weight of 8 × 10 ³ .

Polycarbonate resin (II): a resin represented by the general formula (A), wherein X ₁ = H, X ₂ = H, X ₃ =
H, X ₄ = H, R ₁ and R ₂ form a cyclohexane ring together with the bonding carbon atoms, and have a viscosity average molecular weight of 4 × 10 ⁴ .

The results are shown in the following table.

[0115]

[Table 8]

[0116]

As described above, according to the present invention,
Even if talc contained in the transfer material, which is the main cause of image deletion, adheres to the surface of the photosensitive drum, it mixes high and low molecular weight polycarbonate resin of the surface layer of the photosensitive drum, and applies the toner on the developing sleeve. By reducing the surface roughness, the scraping of the surface layer of the photosensitive drum is promoted, and talc is scraped off together with the surface layer of the photosensitive drum, so that image deletion can be prevented.

Further, when fine powder particles are externally added to the toner used in the present invention, a great effect can be obtained in preventing image deletion.

Further, by integrating the photosensitive drum and the developing device in the process cartridge of the present invention, it is possible to provide the user with the amount of shaving on the photosensitive drum optimized.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an image forming apparatus according to the present invention.

FIG. 2 is a sectional view of a photosensitive drum according to the present invention.

FIG. 3 is a side sectional view of the developing device according to the present invention.

FIG. 4 is a side sectional view of a process cartridge according to the present invention.

FIG. 5 is a graph showing a change in the amount of scraping of the photosensitive drum.

FIG. 6 is a graph showing changes in the weight ratio of consumed external additives.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum (image carrier) 2 Charging roller 3 Developing container 7 Cleaning blade 8 Toner (developer) 9 Developing blade (regulating member) 10 Developing sleeve (developer carrier) 11 Magnet roll 12 Power supply 13 Transfer roller 100 Transfer material Cassette 101 Fixing device 102 Transfer material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G03G 15/08 504 G03G 15/00 556 (72) Inventor Masahiro Yoshida 3- 30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Yusuke Nakazono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Seiichi Shinohara 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside the corporation

Claims (13)

[Claims] At least an image carrier, a developer, a developer carrier for carrying the developer and transporting the developer to a development area, and applying the developer by abutting on the developer carrier. A regulating member for regulating the amount, wherein the developer carrying member carries the developer and conveys the developer to the developing area, and transfers the electrostatic latent image formed on the image carrying member to the developer carrying member. In an image forming apparatus for developing and visualizing by applying a developing bias to a body, the image carrier has a photosensitive layer on a conductive substrate, and the photosensitive layer has a viscosity average molecular weight of 1.5 × 10 ⁴ or less. At least one of the polycarbonate resins (I)
At least one polycarbonate resin (II) having a viscosity average molecular weight of greater than 10 ⁴ , wherein the polycarbonate resin (I) is in a range of 30% by weight to 95% by weight based on the total amount of the polycarbonate resins (I) and (II).
% On the developer carrier, and the amount of the developer applied to the developing region after the regulation by the regulating member is 1.5 mg / cm.
An image forming apparatus, wherein the number is ² or less. 2. A fine powder particle is externally added to a developer, and at least one of the fine powder particles has a particle diameter of 5%.
2. The image forming apparatus according to claim 1, wherein the thickness is from 10 ⁻³ μm to ³ μm, and 0.1 to 5.0 wt% is externally added. 3. The image forming apparatus according to claim 2, wherein at least one kind of charging characteristics of the fine powder particles externally added to the developer has a polarity opposite to that of the charging characteristics of the developer. 4. The image forming apparatus according to claim 2, wherein at least one of the fine powder particles externally added to the developer is an inorganic fine powder particle. 5. The image forming apparatus according to claim 2, wherein at least one of the fine powder particles externally added to the developer is a metal oxide particle. 6. The image forming apparatus according to claim 1, wherein the viscosity average molecular weight of the polycarbonate resin (I) is 1 × 10 ⁴ or less. 7. The polycarbonate resin (I) has a viscosity average molecular weight of 4 × 10 ³ to 1 × 10 ⁴ , and the polycarbonate resin (II) has a viscosity average molecular weight of 8 × 10 ⁴ or less. Item 2. The image forming apparatus according to Item 1. 8. The image forming apparatus according to claim 5, wherein the metal oxide particles are strontium titanate. 9. An image carrier, a developer, a developer carrier for carrying the developer and transporting the developer to a development area, and an amount of the developer applied to the developer carrier in contact with the developer carrier. The developer carrier carries the developer and transports the developer to the development area, and transfers the electrostatic latent image formed on the image carrier to the developer carrier. Means for applying a developing bias to the developing and visualizing means, and the process cartridge detachably mounted to the image forming apparatus main body, wherein the image carrier has a photosensitive layer on a conductive substrate. Wherein the photosensitive layer comprises at least one polycarbonate resin (I) having a viscosity average molecular weight of 1.5 × 10 ⁴ or less;
And at least one polycarbonate resin (II) having a viscosity average molecular weight of greater than × 10 ⁴ , wherein the polycarbonate resin (I) is contained in an amount of 30 to 95% by weight based on the total amount of the polycarbonate resins (I) and (II).
% On the developer carrier, and the amount of the developer applied in the developing area after the regulation by the regulating member is 1.5 mg / cm.
A process cartridge characterized by being ² or less. 10. A fine powder particle is externally added to the developer, and at least one of the fine powder particles has a particle size of 5%.
The process cartridge according to claim 9, wherein the process cartridge has a size of × 10 ⁻³ μm to ³ μm and is externally added at 0.1% by weight to 5.0% by weight. 11. The charge characteristic of at least one of the fine powder particles externally added to the developer is different from the charge characteristic of the developer.
The process cartridge according to claim 7, wherein the process cartridge has a reverse polarity. 12. The process cartridge according to claim 10, wherein at least one of the fine powder particles externally added to the developer is an inorganic fine powder particle. 13. The process cartridge according to claim 10, wherein at least one of the fine powder particles externally added to the developer is a metal oxide particle.