JPH11202525A - Electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic image forming device for preventing the deterioration of an image such as image flow for a long period by introducing an electrification system having improved ecological characteristics of preventing the generation of ozone. SOLUTION: The device is provided with an electrophotographic photoreceptor, a means for electrifying the photoreceptor, a means for forming a latent image with exposure, a means for developing the latent image, a means for transferring the developed image to a transfer material and a means for fixing the image on the transfer material. In this case, the photoreceptor is provided with a photosensitive layer and a surface protecting layer on a supporting body, and the surface protecting layer contains colloidal silica and siloxane resin, and a contact injection electrification system is introduced in the electrifying means, and also, the photoreceptor is equipped with a drum heater constituted of a planar heat generating body in the inside.

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, such as a black-and-white, mono-color or full-color electrophotographic copying machine.
There are a printer and various other recording devices.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors are required to have required sensitivity and electrical characteristics in accordance with an electrophotographic process to be applied. The photoreceptor is required to have durability against electrical or mechanical external forces such as corona charging, toner development, transfer to paper, and cleaning. On the other hand, there is a problem that toner adheres to the surface layer due to repetition of toner development and cleaning. To solve this problem, the cleaning property of the surface layer of the photoconductor must be improved.

In order to satisfy the characteristics required for the surface layer of the photoreceptor as described above, it has been proposed to provide a protective layer mainly composed of a resin on the photosensitive layer.

[0004] With the recent higher quality of copied images,
Electrophotographic photoreceptors having a protective layer having more excellent properties in terms of conductivity, transparency, etc. as well as mechanical strength are being studied.

On the other hand, in an image forming apparatus of an electrophotographic type or an electrostatic recording type, an image bearing member such as an electrophotographic photosensitive member such as selenium, cadmium sulfide, zinc oxide, amorphous silicon and an organic photoconductor, and an electrostatic recording dielectric member. Corona chargers have been used as the body charging processing means, but in recent years, because of their advantages such as low ozone and low power, contact charging devices, that is, charging members that apply a voltage to a member to be charged are used. 2. Description of the Related Art Apparatuses of a type in which an object to be charged is charged by being brought into contact have been put to practical use. In particular, a roller charging type device using a conductive roller as a charging member is preferably used in terms of charging stability.

[0006] In the contact charging system of the roller charging system, a conductive elastic roller as a charging member is brought into pressure contact with a member to be charged, and a voltage is applied to the member to charge the member.

More specifically, since charging is performed by discharging from the charging member to the member to be charged, the charging is started by applying a voltage higher than a certain threshold value.

For example, the thickness of a member to be charged is 25 μm.
In the case where the charging process is performed by pressing the charging roller against the organic photoconductor (OPC photoconductor) of m, the surface potential of the photoconductor can be obtained by applying a voltage of about 640 V or more to the charging roller. Begins to rise, and thereafter, the photoconductor surface potential linearly increases with a slope of 1 with respect to the applied voltage. Hereinafter, this threshold voltage is defined as a charging start voltage Vth.

That is, in order to obtain the photosensitive member surface potential Vd required for electrophotography, the charging roller needs to have Vd + Vth
Therefore, a DC voltage higher than required is required. The contact charging method in which only the DC voltage is applied to the contact charging member to charge the member to be charged in this manner is referred to as a “DC charging method”.

However, in the DC charging method, Vth changes when the resistance value of the contact charging member changes due to environmental changes or the like and the film thickness changes due to the shaving of the photosensitive member as the member to be charged. It was difficult to set the potential to a desired value.

For this reason, as disclosed in Japanese Patent Application Laid-Open No. 63-149669, a peak-to-peak voltage of 2 × Vth or more is applied to a DC voltage corresponding to a desired Vd in order to further uniform charging. An “AC charging method” is used in which a charged object is charged by applying an oscillating voltage having a superposed AC component to a contact charging member. This is for the purpose of the potential smoothing effect of the AC, and the potential of the member to be charged converges to Vd, which is the center of the peak of the AC voltage, and is not affected by disturbances such as the environment.

However, even in such a contact charging system, the essential charging mechanism uses a discharge phenomenon from the charging member to the member to be charged, so that the voltage required for charging as described above is used. Requires a value higher than the surface potential of the member to be charged, and a small amount of ozone is generated.

When the AC charging system is used for uniform charging, the amount of ozone is further generated, and the vibration noise (AC charging noise) between the charging member and the member to be charged due to the AC voltage electric field.
And the deterioration of the surface of the member to be charged due to the discharge becomes remarkable, which is a new problem.

[0014] For this reason, charging by direct injection of charges into the member to be charged has been desired.

The method of applying a voltage to a contact conductive member of a charging roller and injecting a charge into a trap level on the surface of a member to be charged to perform contact injection charging is described in Japan Hardco.
py92, page 287, "Contact Charging Characteristics Using a Conductive Roller", and the like. However, these methods use a low-resistance, low-voltage, voltage-applied photoreceptor to be charged. Is a method for performing contact charging using the charging member described above, which requires that the resistance value of the charging member be low and that a material (conductive filler or the like) for imparting conductivity to the charging member be sufficiently exposed on the surface. Was.

However, when such a charging member having a low resistance value is actually used, an excessive leakage current flows from the contact member to a low-voltage defect such as a flaw or a pinhole generated on the surface of the photoreceptor. Charging failure, enlargement of pinholes, and destruction of electrification of the charging member occur.

In order to prevent this, the resistance of the charging member needs to be about 1 × 10 ⁴ Ω or more. However, the charging member having this resistance lowers the charge injecting property to the photoreceptor and causes the charging to fail. There is a contradiction of not being done.

Therefore, it has been found that by providing a charge injection layer on the surface layer of the photoreceptor, it is possible to inject charges even with a medium-resistance contact charging member, and the problem with the low-resistance charging member can be considerably improved.

However, even in a photoreceptor provided with a charge injection layer, if the resistance of the charge injection layer is lowered in order to perform sufficient charge injection, the electrostatic latent image formed by image exposure laterally flows in a high humidity environment. However, there is a problem that the developed image is blurred. On the other hand, when a charge injection layer having a high resistance range that does not cause image blur is provided, charging failure due to charge injection failure may occur, which is particularly remarkable in a low humidity environment.

The most effective means for preventing charge failure in the charge injection layer having a resistance range that does not cause image blurring in a high humidity environment even in a low humidity environment is to increase the contact probability between the charging member and the charge injection site. It is effective.

For example, in a magnetic brush charging member in which conductive brushes and magnetic particles are arranged in a cylindrical magnet shape, it is expected that the contact probability is improved by increasing the density of the brush or increasing the rotation speed of the brush. I have. Further, if a direct injection charging method using a magnetic brush is used for the charging means, the toner remaining on the photoreceptor after the image is transferred to paper or the like by the transfer means can be collected by the charging means. There is an advantage that cost can be reduced.

[0022]

In recent years, such an electrophotographic image forming apparatus has been widely used even in a high temperature and high humidity climate region such as Southeast Asia.

Also, it has been said that an image forming apparatus using an injection charging method using a magnetic brush does not involve a discharge phenomenon, so that image deletion due to a discharge product does not occur.

However, the paper mainly used for image output in the high-temperature and high-humidity climatic areas described above often contains paper powder such as talc, and the paper adhered to the surface of the photoreceptor while the image forming apparatus was stopped. Since the powder absorbs moisture and lowers the resistance of the surface layer of the photoreceptor, there is a problem that a latent image formed on the photoreceptor laterally flows, so-called image deletion.

An object of the present invention is to solve the above-mentioned problems and to use a charging method which does not generate ozone and has excellent ecological properties.
An object of the present invention is to provide an electrophotographic image forming apparatus in which image deterioration such as image deletion does not occur for a long time.

[0026]

The above problem is a phenomenon caused by moisture absorption of paper powder attached to the photosensitive drum. Because it is impossible to completely remove paper dust,
It is necessary to remove the moisture absorbed by the paper powder by thermal means and prevent the surface layer of the photoreceptor from lowering its resistance. Therefore, in the present invention, the temperature of the photosensitive drum is raised by operating the planar heating element provided inside the photosensitive member between the time when the main switch of the image forming apparatus is turned on and before the image formation is started. By blowing off the moisture, the image flow due to the lowering of the resistance of the surface layer is prevented.

That is, the present invention provides an electrophotographic photosensitive member, means for charging the photosensitive member, means for forming a latent image by exposure, means for developing the latent image, means for transferring the developed image to a transfer material. And an electrophotographic image forming apparatus having means for fixing an image on a transfer material, wherein the photoreceptor has a photosensitive layer and a surface protective layer on a support, and the surface protective layer contains colloidal silica and a siloxane resin. An electrophotographic image forming apparatus, wherein the charging means is of a contact injection charging type, and the photoreceptor has a drum heater formed of a planar heating element therein.

The siloxane resin described in the present invention is:
It means a silicone resin or a partially condensed oligomer obtained by condensation of a silicon compound having three hydrolyzable groups such as an OH group and an OR group per silicon atom.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The surface protective layer of the electrophotographic photosensitive member of the present invention comprises
Contains colloidal silica and siloxane resin,
The composition for an electrophotographic photoreceptor surface protective layer used in the present invention is formed by applying the composition to the surface of the electrophotographic photoreceptor, drying and curing. The composition for a surface protective layer of an electrophotographic photoreceptor used in the present invention comprises at least the following (a) to (c):
Consists of components. (A) Colloidal silica (b) Siloxane resin formed by partial condensation of R-Si (OR ') ₃ (where R is an alkyl group having 1 to 3 carbon atoms, a vinyl group, C _n F _{2n + 1} C ₂ H ₄ — group (n = 1 to 1)
8) represents at least one group selected from the group consisting of a γ-glycidoxypropyl group and a γ-methacryloxypropyl group. R 'represents at least one group selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 3 carbon atoms. (C) at least one solvent selected from the group consisting of lower aliphatic alcohols and water. The composition for a surface protective layer of an electrophotographic photoreceptor is a mixed solution of colloidal silica and a siloxane resin of 1 to 50% by weight of a lower alcohol-water. Those dispersed therein are preferred. If the solids content exceeds 50% by weight, the composition is liable to be deteriorated, and it is difficult to form a good coating film due to gelation or the like. If it is less than 1% by weight, the strength of the formed surface protective layer tends to be insufficient.

The proportion of the colloidal silica in the solid content is preferably from 10 to 70% by weight, and the content of the siloxane resin is preferably from 30 to 90% by weight. If the ratio of the siloxane resin to the solid content is less than 30% by weight, the film tends to be brittle and a good film is not easily formed and cracks and the like tend to be easily formed. If the ratio of the colloidal silica is less than 10% by weight, the formed surface protective layer has Hardness tends to be insufficient.

As the colloidal silica, a commercially available aqueous dispersion type is used (trade names “Ludox” and “Na”).
lcoag "). The particle size is preferably from 5 to 150 nm, and from the viewpoint of dispersion stability and optical characteristics, from 10 nm to 30 nm.
nm is more preferable. As colloidal silica, the content of an alkali metal oxide such as Na ₂ O is preferably less than 2% by weight. As the dispersing solvent, a mixed solvent system of water and a lower aliphatic alcohol such as methanol, ethanol, isopropanol, t-butanol and n-butanol is preferable, but other water-soluble solvents such as glycol and acetone may be further added. Good.

The composition for the surface protective layer of the electrophotographic photoreceptor has a pH of from 3.0 to 6.0 by using an inorganic acid or an organic acid.
It is preferably adjusted to an acidic state of 0. If a strong acid is used, the stability of the composition and the like are likely to be unfavorably affected.
Is adjusted to an acidic state.

The composition for the surface protective layer of the electrophotographic photosensitive member applied to the surface of the electrophotographic photosensitive member is dried and then heat-cured to exhibit hardness, strength, low surface energy and discharge resistance. Thermal curing proceeds more completely at higher temperatures,
It is selected in a range that does not adversely affect the characteristics of the electrophotographic photosensitive member. The thermosetting is preferably carried out at 80 to 180 ° C, more preferably at 100 to 150 ° C.

The longer the thermal curing time, the more the curing proceeds, but the thermal curing time is selected within a range that does not adversely affect the characteristics of the electrophotographic photosensitive member at the processing temperature. The heat curing treatment time is generally about 10 minutes to 12 hours.

The surface protective layer obtained by drying and then heat curing contains at least a component represented by SiO ₂ as colloidal silica and a siloxane resin represented by RSiO _3/2 .

Here, R is an alkyl group having 1 to 3 carbon atoms,
Vinyl _{group, C n F 2n + 1 C} 2 H 4 - group (n = 1~18),
represents at least one group selected from the group consisting of a γ-glycidoxypropyl group and a γ-methacryloxypropyl group.

The thickness of the surface protective layer is preferably 0.1 to 4 μm. If the thickness is less than 0.1 μm, the surface hardness and strength are not sufficient, and the durability tends to decrease. If the thickness exceeds 4 μm, the contrast potential formed by a latent image during development tends to deteriorate. More preferably, it is 0.2 to 3 μm.

The surface protective layer preferably has a low surface energy in order to satisfy the cleaning property and the stain resistance, and the low surface energy measured by the contact angle of water is preferably 90 ° or more. If the angle is less than 90 degrees, a charge product, toner, or falling off from paper is liable to adhere to the surface due to repeated use in the electrophotographic process, and deterioration of a latent image (image deletion) due to poor cleaning or a decrease in surface resistance is likely to occur. It is more preferably at least 95 degrees.

Further, as a feature of the surface protective layer, since it contains colloidal silica and a siloxane resin, an extremely high surface hardness can be obtained as compared with ordinary organic compounds. The surface hardness is appropriately selected from the balance with various physical properties depending on the content of the colloidal silica and the structure of the siloxane resin, and the pencil hardness of the film formed on the glass plate is preferably 5H or more. If it is less than 5H, the toner and paper powder used in the electrophotographic process are apt to cause scratches and scraping.

The volume resistance of the surface protective layer is 1 × 10 ⁹ to 1 ×.
It is preferably 10 ¹⁵ Ωcm. 1 × 10 ⁹ Ωcm
If it is less than 1 × 10 ¹⁵ Ωcm, the charge of the latent image formed is liable to be diffused, and if it exceeds 1 × 10 ¹⁵ Ωcm, the charge cannot move sufficiently until development after exposure as an electrophotographic photoreceptor, and apparently the sensitivity is lowered. , The residual potential tends to be high.

Further, not only the potential resistance but also the remaining hydrolyzable group such as a silanol group tends to increase the residual potential. Therefore, it is desirable that the residual potential is minimized. Preferably, the ratio of the hydrolyzable group in terms of SiOH group is 0.1% by weight or less, more preferably 0.01% by weight or less.

For the surface protective layer, a resin composition containing colloidal silica and a siloxane resin as essential components is used.
These are described in US Pat. No. 4,270,073 and US Pat.
It can be produced by the method described in 944702.

The silicone hard coat resin comprises a hydrolytic condensate of a polyfunctional organosilicon compound having a hydrolyzable group in the molecule. The greater the number of functional groups, the higher the strength, and the resulting resin becomes harder. Among them, 4
In the case of using colloidal silica in place of the functional organosilicon and using trifunctional organosilicon, the hardness is adjusted by adjusting the particle size of colloidal silica, the amount of colloidal silica added, and the hydrolytic condensation of the trifunctional organosilicon. A resin which is high and excellent in film forming properties can be obtained. A preferred colloidal silica has an average particle diameter of 5 to 150 nm, which is dispersed in a lower alcohol containing water within the above-described range, and a trifunctional organosilicon compound having a hydrolyzable group is acidified or alkalinized. It is produced by hydrolysis in the presence. After completion of the reaction, a lower alcohol, a curing catalyst, a leveling agent and the like are further added as necessary. This is coated on a plastic substrate by dip, spray, bar coating, spin coating, or the like. After removing the solvent, a coating is generally formed by heating and curing at 80 to 150 ° C. The curing temperature is preferably performed at a temperature equal to or lower than the thermal deformation temperature of the coated base plastic. The siloxane resin thus formed has a pencil hardness of several H-9.
H hardness can be exhibited. Depending on the applied substrate material, the hard coat resin may be subjected to a surface treatment with a silane compound called a silane coupling agent, or a chemical or physical method, for the purpose of improving adhesion to the substrate surface. It is common practice to modify the surface to improve adhesion.

Next, the structure of the photosensitive member used in the present invention will be described.

The support may be any material having conductivity, such as metal such as aluminum and stainless steel, metal provided with a conductive layer, plastic and paper. Film-like and the like.

When an image input such as LBP is a laser beam, a conductive layer may be provided for the purpose of preventing interference fringes due to scattering or covering a substrate. This can be formed by dispersing conductive powder such as carbon black and metal particles in a binder resin. The thickness of the conductive layer is 5
It is preferably 40 μm, more preferably 10 to 30 μm.

An intermediate layer having an adhesive function is provided thereon. Examples of the material of the intermediate layer include polyamide polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, and polyether urethane. These are applied by dissolving in an appropriate solvent. The thickness of the intermediate layer is preferably 0.1 to 5 μm,
More preferably, it is 0.3-1 μm.

On the intermediate layer, a coating liquid in which a charge generation material such as a phthalocyanine pigment, an azo pigment, and an anthrone pigment is dissolved in a binder resin dissolved in a solvent is applied.
Dry to form a charge generation layer. As the binder resin used here, for example, polyester resin, polyacryl resin, polyvinyl carbazole resin, phenoxy resin,
Polycarbonate resins, polystyrene resins, polyvinyl acetate resins, polysulfone resins, polyarylate resins, vinylidene chloride, acrylonitrile copolymers, polyvinyl benzal resins, and the like are mainly used.
The ratio of the pigment to the binder resin is preferably from 1/1 to 10/1, and more preferably from 1.5 / 1 to 3/1.

The charge transport layer is formed by applying a coating material in which a charge transport material and a binder resin are dissolved in a solvent and then drying the coating material. Examples of the charge transport material to be used include various triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.

Examples of the binder resin include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylate, methacrylate, vinylidene fluoride and trifluoroethylene, polyvinyl alcohol, polyvinyl acetal, and polycarbonate. , Polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, epoxy resin and the like.

When the photosensitive layer is of a single type, the above-mentioned substances can be used. In particular, as the charge transporting material, a charge transfer complex comprising a combination of poly-N-vinylcarbazole and trinitrofluorene or the like is further used. It can also be used.

In the present invention, an intermediate layer can be provided between the photosensitive layer and the protective layer in order to further improve the adhesiveness, coatability and the like. Materials used include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, alcohol-soluble polyamide, polyurethane, gelatin, aluminum oxide and the like.

The structure of the charging member used in the present invention is shown below.

In the present invention, a magnetic brush using magnetic particles as a charging member is preferably used. As the magnetic particles, a resin and a magnetic material such as magnetite are kneaded and formed into particles, or a mixture of conductive carbon or the like for resistance adjustment, sintered magnetite, ferrite, or a reduction treatment of these. It is possible to use those in which the resistance value is adjusted by applying a resin coating, or those in which the resistance value is adjusted by plating these magnetic particles. 10 ⁴ to 10 ⁷ Ωc as the resistance value of the magnetic particles
m is used. If it is less than 10 ⁴ Ωcm, leakage of the photoreceptor and adhesion of magnetic particles to the photoreceptor will occur. If it exceeds 10 ⁷ Ωcm, the charge will not be sufficiently injected and poor charging will occur. In order to form a charging member using magnetic particles as a magnetic brush, the charging member is held by a magnetic force on a conductive magnet roll or a non-magnetic conductive sleeve containing the magnet roll.

The magnetic brush constructed as described above is arranged so as to be in contact with the photosensitive member and is rotated as necessary. The direction of rotation may be either forward or reverse with respect to the photoreceptor, but reverse rotation may be more advantageous because the contact probability increases due to a difference in peripheral speed.

[0057]

The present invention will be described below with reference to examples. In the examples, "parts" indicates parts by weight.

Specific examples of the preparation of the coating liquid used for forming the surface protective layer of the present invention are shown below.

Preparation Example 1 30.0 g of an aqueous dispersion of colloidal silica (solid content: 40% by weight) was placed in a flask, and a mixture of 21.5 g of methyltrimethoxysilane and 3.5 g of acetic acid was stirred while stirring.
/ 3 was added. After the addition, the mixed solution was heated to 55 ° C. Immediately after a sharp exotherm was observed, the mixture was cooled with ice, and the remaining mixture was added while maintaining the temperature in the flask at 50 to 60 ° C. Cool the reaction solution to 20 ° C. and stir for 30 minutes when the temperature stabilizes. Thereafter, the reaction solution was diluted with 17.8 g of isopropyl alcohol, 2.8 g of dibutyltin di-2-ethylhexoate was gradually added, and benzyltrimethylammonium acetate 2.4 was used as a curing catalyst.
g, and then 0.16 g of a 10% by weight solution of polyether-modified dimethyl silicone in ethanol. The resulting reaction mixture was free of precipitate.

Preparation Example 2 3.9 g of an aqueous dispersion of colloidal silica (solid content: 40% by weight) was placed in a flask, and 26.8 g of an isopropyl alcohol dispersion of colloidal silica (solid content: 30% by weight) was added to the flask while stirring. 1.5 g of ethoxysilane, γ
1.9 g glycidoxypropyltrimethoxysilane,
3,3,4,4,5,5,6,6,6-Nonafluorohexyltrimethoxysilane 2.4 g and acetic acid 3.1 g were added. After the addition, the mixed solution is heated to 65-70 ° C,
The reaction was performed for 2 hours. Then, isopropyl alcohol 2
The mixture was diluted with 3.3 g, 2.4 g of benzyltrimethylammonium acetate was added as a curing catalyst, and 0.16 g of a 10% by weight ethanol solution of polyether-modified dimethyl silicone was added. [Example 1] A 30φ, 260mm aluminum cylinder was used as a support, and a coating composed of the following materials was applied on the support by a dip coating method.
The composition was thermally cured at 30 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm.

Conductive pigment: tin oxide-coated titanium oxide 10 parts Resistance controlling pigment: titanium oxide 10 parts Binder resin: phenol resin 10 parts Leveling agent: silicone oil 0.001 part Solvent: methanol / methyl cellosolve = 1/1 ... 20 parts Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymerized nylon in 65 parts of methanol and 30 parts of n-butanol was applied thereon by dip coating. Then, an intermediate layer having a thickness of 0.5 μm was formed. Next, C
uKα characteristic X-ray diffraction Bragg angle 2θ ± 0.2 ° 2
Disperse 4 parts of oxytitanium phthalocyanine (TiOPc) having strong peaks at 3.9 ° and 27.1 °, 2 parts of polyvinyl butyral (trade name: SREC BM-2, manufactured by Sekisui Chemical) and 80 parts of cyclohexanone for 4 hours using a sand mill. After that, 115 parts of methyl ethyl ketone was added to obtain a dispersion for a charge generation layer. This was applied on the intermediate layer by a dip coating method to form a charge generation layer having a thickness of 0.3 μm.

Next, the following structural formula

[0063]

Embedded image Is dissolved in a mixed solution of 20 parts of dichloromethane and 40 parts of monochlorobenzene, and this solution is applied on the charge generation layer by a dip coating method,
After drying at 120 ° C. for 60 minutes, a charge transport layer having a thickness of 18 μm was formed.

Next, the above-mentioned preparation liquid 1 was applied on the above-mentioned charge transport layer by a dip coating method and dried at 120 ° C. for 2 hours to form a surface protective layer having a thickness of 2 μm. [Example 2] In the same manner as in Example 1, coating was performed on an aluminum cylinder up to the charge transport layer, and Preparation Solution 2 was applied on the charge transport layer by dip coating, and dried at 120 ° C for 2 hours.
A surface protective layer having a thickness of 3 μm was formed. <Preparation of Charging Member> 100 parts of magnetite was added to a polystyrene resin, kneaded and pulverized to obtain magnetic particles having a particle diameter of 30 μm and a resistance value of 1 × 10 ⁶ Ω.

The magnetic particles were coated on a magnet roller with a thickness of 1 mm to form a magnetic brush, and a charging nip having a width of about 2 mm was provided between the magnetic roller and the photosensitive member. The magnetic brush was rotated so as to rub in the opposite direction at a speed one time faster than the peripheral speed of the surface of the photoconductor, so that the photoconductor and the magnetic brush were uniformly contacted. <Example of Image Forming Apparatus> FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus. The image forming apparatus of this embodiment is a laser beam printer using a transfer type electrophotographic process.

Reference numeral 1 denotes a magnetic brush charger serving as a contact charging member that is in contact with the photosensitive member.
A DC bias of 00V is applied, and the outer peripheral surface of the photoconductor is charged to approximately -680V.

Exposure device 3
As a result, a laser beam corresponding to the image signal is emitted, and a latent image is formed on the photosensitive drum 2. The latent image is reversely developed as a toner image by a reversal developing device 4 using a magnetic one-component insulating negative toner. On the other hand, a transfer material P as a recording material is supplied from a paper supply unit (not shown), and is introduced at a predetermined timing into a press nip (transfer portion) between the rotary photosensitive member 2 and the transfer roller 5. A transfer bias voltage is applied to the transfer roller 5. In this embodiment, the roller resistance value is 5 × 1
Using the transfer roller 5 0 ⁸ Omega, it was transferred by applying a DC voltage of + 2000V. Transfer material P introduced into the transfer section
The transfer unit is conveyed in a sandwiched manner, and the toner image formed and carried on the surface of the rotary photoreceptor 2 is sequentially transferred to the front side by electrostatic force and pressing force. The transfer material P to which the toner image has been transferred is separated from the surface of the photoreceptor 2 and introduced into a fixing device such as a heat fixing method (not shown) to fix the toner image and to form an image formed product (print or copy). It is discharged outside the device.

FIG. 2 is a schematic view of a sheet heating element. A heating pattern (not shown) is printed on the planar heating element 6.
By applying a voltage thereto, heat is generated by the heat generation pattern of the planar heating element. In this embodiment, the device is driven at 13 V, and the time required to reach 50 ° C. is 10 seconds. This sheet heating element has an adhesive sheet on the back side of the heating pattern, and since this adhesive portion is attached and mounted on the inner surface of the photosensitive drum, there is no air gap between the photosensitive element 2 and the heating element. It is possible to efficiently transfer the generated heat to the photoconductor. In FIG. 2, the sheet heating element is shown protruding from the photoconductor for the explanation of the embodiment, but in fact, the sheet heating element is entirely hidden inside the photoconductor.

The electrophotographic photosensitive member having the layer which also functions as the surface protective layer and the charge injection layer in Examples 1 and 2 was mounted on the image forming apparatus of this example, and an image was output. Transfer materials include JK-BOND paper, JK-Copier paper and Xero
The image deterioration was examined after leaving the image forming apparatus in a high-temperature and high-humidity environment (32.5 ° C., 80% RH) overnight after outputting 1000 sheets of x4024 paper.

Since the operation of the sheet heating element needs to be completed before the start of image formation, the sheet heating element is driven at 13V. At this time, the temperature rises from 32.5 ° C to 50 ° C.
C., which is 10 seconds, which is sufficiently shorter than the time required until the start of image formation (FIG. 3). After the start of image formation, the temperature in the image forming apparatus rises due to the driving of the fixing unit and the like, and there is no further moisture absorption.

Table 1 shows the relationship between the drum surface temperature and the image for the photosensitive members of Example 1 and Table 2 for Table 2.
The temperature of the surface of the planar heating element is about 4 ° C. higher than the surface temperature of the drum. A character image was output, and the level of image deterioration was evaluated in five levels.

1. 1. No output (all latent images are flowing sideways) 2. Level of horizontal flow (some characters cannot be distinguished) 3. During horizontal flow level (horizontal and vertical lines of characters are attached) 4. Small horizontal flow level (thicker characters) Same as the initial image (no image degradation) JK-BOND paper or J
When a paper having a large amount of talc such as K-Copier paper is used as a transfer material, if the apparatus after image output is left in a high-temperature and high-humidity environment, the paper powder absorbs moisture and lowers resistance. However, in the case of Xerox 4024 paper, the degree of image deletion was such that characters were crushed, and did not deteriorate so much. Next, by mounting a drum heater inside the photoconductor and raising the drum surface temperature,
By removing the moisture adsorbed by the paper dust, the image deletion could be restored. From the table, JK-BON with much paper dust
In the case of D paper or JK-Copier paper, it was found that the drum surface temperature needs to be higher than the ambient temperature by 10 ° C. or more in order to keep the image quality at the same level as the initial image output.

Next, a durability deterioration test was performed using this apparatus. The amount of abrasion of the surface layer after outputting 4000 images was 0.33 μm in the photoreceptor of Example 1, and 0.46 μm in the photoreceptor of Example 2, which was a small amount of abrasion, and sufficiently functioned as a surface protective layer. Further, even after the output of 4000 sheets, the photoconductor surface potential of the photoconductor 1 of the first embodiment is -67 with respect to the application of the voltage of the magnetic brush charger of -700 V.
0 V and -675 V for the photoreceptor of Example 2, and the charge injecting property was also very good.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

As described above, in an image forming apparatus using a magnetic brush charger as a charger, the surface layer of an electrophotographic photosensitive member having a photosensitive layer on a conductive support is charged by charge injection from a charging member. A charge injection layer and a surface protective layer, wherein the surface protective layer is made of a resin having colloidal silica and a siloxane bond, and a JK-BOND
It is possible to provide an image forming apparatus capable of obtaining a high-quality image without image deletion even when a transfer material having a large amount of paper dust, such as paper or JK-Copier paper, is used.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an electrophotographic photosensitive member used in Examples and an electrophotographic image forming apparatus having the same.

FIG. 2 is a schematic view of a drum heater composed of a planar heating element.

FIG. 3 is a diagram showing a temperature change of a drum heater.

Continuation of the front page (72) The inventor ▲ Taka ▼ Tadashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (3)

[Claims] 1. An electrophotographic photosensitive member, means for charging the photosensitive member, means for forming a latent image by exposure, means for developing the latent image, means for transferring the developed image to a transfer material, and An electrophotographic image forming apparatus having a means for fixing the image of (1), wherein the photosensitive member has a photosensitive layer and a surface protective layer on a support, the surface protective layer contains colloidal silica and a siloxane resin, and the charging means Is a contact injection charging system,
And an electrophotographic image forming apparatus, wherein the photosensitive member has a drum heater made of a sheet heating element inside. 2. An electrophotographic image forming apparatus according to claim 1, wherein said contact injection charging method is such that a magnetic brush is brought into contact with a photoconductor and a voltage is applied to inject and charge the photoconductor. 3. The following formula (I) RSiO _3/2 (I) wherein R is an alkyl group having 1 to 3 carbon atoms, a vinyl group, a C group, wherein the protective layer is condensed in the presence of colloidal silica.
_{n F 2n + 1 C 2 H} 4 - represents a group (n = 1~18), γ- glycidoxypropyl group and .gamma.-methacryloxypropyltrimethoxysilane oxypropylate 0 at least one group selected from the group consisting of Le group. 3. The compound according to claim 1, which comprises a compound represented by the formula:
2. The electrophotographic photoreceptor of claim 1.