JP3950559B2 - Electrophotographic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic apparatus such as a copying machine or a printer using an electrophotographic photosensitive member based on an electrophotographic system.
[0002]
[Prior art]
In the electrophotographic method, as shown in US Pat. No. 2,297,691, the electric resistance changes depending on the dose received during image exposure, and in the dark, a support coated with an insulating material is used. A photoconductive material is used. As basic characteristics required for an electrophotographic photoreceptor using this photoconductive material,
(1) It can be charged to an appropriate potential in the dark.
(2) Less potential dissipation in the dark,
(3) Dissipate charges quickly by light irradiation,
Etc.
[0003]
Conventionally, as an electrophotographic photosensitive member, an inorganic photosensitive member having a photosensitive layer mainly composed of an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide has been widely used. However, these satisfy the above conditions (1) to (3), but are not necessarily satisfactory in terms of thermal stability, moisture resistance, durability, and productivity.
[0004]
In order to overcome the drawbacks of inorganic photoreceptors, electrophotographic photoreceptors based on various organic photoconductive compounds as main components have been actively developed in recent years. For example, US Pat. No. 3,378,851 discloses a photoreceptor having a charge transport layer containing triallylpyrazoline, US Pat. No. 3,871,880 discloses a charge generation layer comprising a derivative of perylene pigment, and a condensate of 3-propylene and formaldehyde. A photoconductor comprising a charge transport layer comprising, is known.
[0005]
Furthermore, the organic photoconductive compound can freely select the photosensitive wavelength range of the electrophotographic photosensitive member depending on the compound. For example, for azo pigments, JP-A 61-272754 and JP-A 56-167759. The substances disclosed in the gazette are disclosed to exhibit high sensitivity in the visible region, and the compounds disclosed in JP-A-57-19576 and JP-A-61-228453 are sensitive to the infrared region. It is recommended to have
[0006]
Among these materials, those showing sensitivity in the infrared region are used in laser beam printers (hereinafter abbreviated as LBP) and LED printers that have made remarkable progress in recent years, and the demand frequency thereof is increasing.
[0007]
Electrophotographic photoreceptors using these organic photoconductive compounds are used as function-separated photoreceptors in which a charge transport layer and a charge generation layer are laminated in order to satisfy both electrical and mechanical properties. There are many cases. On the other hand, as a matter of course, the electrophotographic photosensitive member is required to have sensitivity, electrical characteristics, and optical characteristics according to the applied electrophotographic process.
[0008]
In particular, in electrophotographic photoreceptors that are used repeatedly, electrical and mechanical external forces such as corona or direct charging, image exposure, toner development, transfer process, and surface cleaning are directly applied to the surface of the electrophotographic photoreceptor. , Durability against them is also required.
[0009]
Specifically, it can be used for electrical degradation caused by ozone and nitrogen oxides during charging, mechanical discharge in which the surface is worn or scratched due to discharge during charging, or rubbing of the cleaning member, and electrical degradation. Durability is required.
[0010]
Mechanical degradation is particularly different from inorganic photoreceptors. Organic photoreceptors that are often soft in material are inferior in durability against mechanical degradation, and improvement in durability is particularly desired.
[0011]
In recent years, direct charging systems such as those disclosed in Japanese Patent Application Laid-Open Nos. 57-17826 and 58-40566 have been mainly used, in which a voltage is directly applied to a charging member and electric charges are applied to an electrophotographic photosensitive member. is there.
[0012]
This is a method in which a roller-shaped charging member made of conductive rubber or the like is directly brought into contact with the electrophotographic photosensitive member to apply a charge. Compared with a scorotron or the like, the amount of ozone generated is significantly smaller. About 80% of the current flowing through the device is wasted because it flows to the shield, whereas direct charging does not have this wasted amount and is very economical.
[0013]
However, direct charging has a drawback that charging stability is very poor because it is charged by discharge according to Paschen's law. As a countermeasure, a method of irradiating light before charging or substantially simultaneously, or a so-called AC / DC charging method in which an AC voltage is superimposed on a DC voltage has been devised (Japanese Patent Laid-Open No. 63-149668).
[0014]
Although the charging stability has been improved by this charging method or the like, the charging voltage must be increased in order to compensate for the decrease in charging ability caused by the pre-charging exposure. In addition, in the method of superimposing AC, the amount of discharge on the surface of the electrophotographic photosensitive member is greatly increased, and dielectric breakdown occurs due to minute defects of the electrophotographic photosensitive member, resulting in image defects. Electrophotographic photoreceptors are required to have a higher withstand voltage than before.
[0015]
In the case of a function-separated type photoreceptor composed of a charge generation layer and a charge transport layer, the micro defects of the electrophotographic photoreceptor are mainly present in the charge transport biolayer. This is one in which minute bubbles present in the coating material of the charge transport layer are taken in at the stage of manufacturing the charge transport layer.
[0016]
In addition, as one method for improving the mechanical durability of the electrophotographic photosensitive member, it is effective to reduce the friction coefficient of the electrophotographic photosensitive member. As a means for this, the surface layer of the electrophotographic photosensitive member is lubricated. A method of adding is proposed. Specifically, JP-A Nos. 52-117134, 53-107841, 54-26740, 54-27434, 54-86340, 54-143142, 54-143148, 56-9345, 56-126838, 57-14845, 57-74748, 57-35863, 57-76553, 58-44444, 58-70229, 58- No. 102949, No. 58-163958, No. 59-97042, No. 62-272281, No. 63-30850, No. 63-56658, No. 63-58352, No. 63-58450, No. 63-61255 63-61256, 63-65449, 63-65450, 63-65451, 63-73267 , The 63-221355 JP, same 63-249152 JP, those proposed in such same 63-311356 JP.
[0017]
As the lubricant, fluorine resin powder such as polytetrafluoroethylene is particularly suitable.
[0018]
[Problems to be solved by the invention]
However, in order to contain the fluororesin powder in the surface layer of the electrophotographic photoreceptor, it is necessary to uniformly disperse it in the coating material of the surface layer. As this method, it is effective to use a surfactant as a dispersion aid, but this makes it easier for fine bubbles to be taken into the paint, so that the electrophotographic apparatus using the direct charging method as described above. When an electrophotographic photosensitive member having this surface layer is used, there arises a problem that dielectric breakdown occurs from the minute defects and becomes image defects.
[0019]
An object of the present invention is to provide an electrophotographic apparatus that can prevent the occurrence of image defects due to leakage of an electrophotographic photosensitive member in a direct charging method and can stably supply a high-quality image having a long durability life.
[0020]
[Means for Solving the Problems]
That is, the present invention relates to an electrophotographic apparatus that forms an image by applying an image forming process including a step of charging the surface of the charged body to the charged body by a charging processing unit.
It said member to be charged is, a charge transport layer formed by the charge generating layer and a dip coating on a conductive substrate laminated in this order, a charge transport layer formed by the dip coating is a electrophotographic photoreceptor which is a surface layer And
The surface layer contains a charge transport material, a binder resin and a silicone-based antifoaming agent, the silicone-based antifoaming agent is dimethylpolysiloxane, and the content of dimethylpolysiloxane in the surface layer is 0 with respect to the binder resin. 0.002 to 0.01% by weight,
The electrification processing means for the object to be charged is achieved by an electrophotographic apparatus which is a direct charging device for charging the surface of the object to be charged by bringing a charging member to which a voltage is applied into contact with the object to be charged.
[0021]
The electrophotographic photosensitive member used in the present invention has particularly excellent withstand voltage and durability.
[0022]
In the present invention, the electrophotographic photosensitive member contains dimethylpolysiloxane having excellent defoaming property in the surface layer of the photosensitive member, thereby eliminating the fine bubbles of the paint at the time of coating the photosensitive layer. It is estimated that it has improved.
[0023]
In particular, it is effective in an electrophotographic photosensitive member containing a fluororesin powder as a lubricant in the surface layer.
[0024]
The structure of the electrophotographic photoreceptor used in the present invention will be described below.
[0025]
As the silicone-based antifoaming agent, dimethylpolysiloxane is excellent, and the addition amount is 0.002 to 0.01% by weight with respect to the binder resin .
[0026]
Fluorine resin powders include tetrafluoroethylene resin, trifluoroethylene resin, tetrafluoroethylene-6fluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluoroethylene chloride, and their A typical example is a copolymer.
[0027]
The electrophotographic photosensitive member in the present invention may be a single layer type in which the photosensitive layer contains the charge transport material and the charge generation material in the same layer, or a stacked type in which the charge transport layer and the charge generation layer are separated. In view of photographic characteristics, a laminated type is preferable.
[0028]
Any conductive substrate may be used as long as it has conductivity. Examples thereof include metals such as aluminum and stainless steel, metals provided with a conductive layer, paper, and plastics. Examples of the shape include sheets and cylinders. .
[0029]
When image input such as LBP is laser light, a conductive layer may be provided for the purpose of preventing interference fringes due to scattering or covering a scratch on the 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 to 40 μm, preferably 10 to 30 μm.
[0030]
An intermediate layer having an adhesive function is provided thereon. Examples of the material for the intermediate layer include polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, and polyether urethane. These are dissolved in an appropriate solvent and applied. The thickness of the intermediate layer is 0.05 to 5 μm, preferably 0.3 to 1 μm.
[0031]
A charge generation layer is formed on the intermediate layer. Examples of the charge generation material used in the present invention include selenium-tellurium, pyrylium, thiapyrylium dyes, phthalocyanine, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone, and asymmetric quinocyanine pigments. It is done. In the case of the functional separation type, the charge generation layer is composed of the charge generation material 0.3 to 4 times the amount of binder resin and solvent, homogenizer, ultrasonic dispersion, ball mill, vibration ball mill, sand mill, attritor, roll mill, and liquid collision. It is well dispersed by a method such as a mold type high-speed disperser, and the dispersion is applied and dried. The film thickness of the charge generation layer is 5 μm or less, preferably 0.1 to 2 μm.
[0032]
The charge transport layer is formed by applying and drying a paint in which a charge transport material, a binder resin, and dimethylpolysiloxane are mainly dissolved in a solvent.
[0033]
If necessary, a fluororesin powder is dispersed and used as a lubricant.
[0034]
Examples of the charge transport material include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, thiazole compounds, and the like.
[0035]
Examples of the binder resin include resins selected from acrylic resins, styrene resins, polyesters, polycarbonate resins, polyarylate, polysulfone, polyphenylene oxide, epoxy resins, polyurethane resins, alkyd resins, and unsaturated resins.
[0036]
These are combined with 0.5 to 2 times the amount of the binder resin, coated and dried to form a charge transport layer. The thickness of the charge transport layer is 5 to 40 μm, preferably 15 to 30 μm.
[0037]
Further, the charge generation layer or the charge transport layer can contain various additives such as an antioxidant and an ultraviolet absorber.
[0038]
A specific example of the electrophotographic apparatus of the present invention is shown in FIG. In this apparatus, a roller-shaped charging member 2, an image exposure means 3, a developing device 4, a paper feed roller and paper feed guide 5, a transfer roller 6, a cleaner 7, and a pre-exposure means 8 are provided on the peripheral surface of the electrophotographic photosensitive member 1. It has an arranged configuration.
[0039]
In the image forming method, first, a voltage is applied to the charging member 2 disposed in contact with the electrophotographic photosensitive member 1 to charge the surface of the electrophotographic photosensitive member 1, and the image corresponding to the original is exposed by the image exposure unit 3. The body 1 is image-exposed to form an electrostatic latent image. Next, the electrostatic latent image on the electrophotographic photosensitive member 1 is developed (visualized) by attaching toner in the developing device 4 to the electrophotographic photosensitive member 1.
[0040]
Further, the toner image formed on the electrophotographic photosensitive member 1 is transferred by a transfer roller 6 onto a transfer material such as paper fed through a paper supply roller and a paper supply guide 5, and is not transferred to the transfer material by a cleaner 7. The residual toner remaining on the electrophotographic photosensitive member 1 is collected. In the case where residual charges remain inside the electrophotographic photosensitive member 1, it is better to remove the charge by applying light to the photosensitive member 1 by the pre-exposure means 8. On the other hand, the transfer material on which the toner image is formed is sent to a fixing device (not shown) by the transport unit 9 to fix the toner image.
[0041]
In this electrophotographic apparatus, the light source of the image exposure means 3 can use halogen light, fluorescent light, laser light, or the like. Moreover, you may add another auxiliary | assistant process as needed.
[0042]
【Example】
This will be described in accordance with the following examples.
[0043]
Example 1
4 parts of conductive carbon was melt-kneaded with 100 parts of urethane rubber, and a roller-shaped charging member was formed so as to have a diameter of 16 mm × 320 mm with a stainless steel core having a length of 5 mm and a length of 350 mm as a central axis.
[0044]
Next, an electrophotographic photoreceptor was prepared as follows.
[0045]
A 30φ357.5 mm Al cylinder was used as a support, and a coating material composed of the following materials was applied on the support by a dipping method and thermally cured at 140 ° C. for 30 minutes to form a 15 μm conductive layer.
[0046]
Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: Titanium oxide 2 parts Binder resin: Phenol resin 6 parts Leveling material: Silicone oil 0.001 part Solvent: Methanol, methoxypropanol 0.2 / 0.8 20 copies [0047]
Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol was applied by a dipping method to form a 0.5 μm intermediate layer.
[0048]
Next, TiOPc4 part and polyvinyl butyral (trade names) whose diffraction angles 2θ ± 0.2 ° in the X-ray diffraction spectrum of CuKα have strong peaks at 9.0 °, 14.2 °, 23.9 °, and 27.1 °. : ESREC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were dispersed in a sand mill using φ1 mm glass beads for 4 hours, and then 100 parts of ethyl acetate was added to prepare a dispersion for a charge generation layer. This was applied by a dipping method to form a charge generation layer having a thickness of 0.3 μm.
[0049]
Next, 9 parts of an amine compound of the following structural formula:
[Chemical 1]
[0051]
1 part of amine compound of the following structural formula
[Chemical 2]
[0053]
A polycarbonate resin (trade name Panlite L-1250: manufactured by Teijin Chemicals Ltd.) and 10 parts of silicone antifoaming agent according to the present invention di-methyl polysiloxane (trade name SH200: Dow Corning Toray Silicone Co., 0.0002 parts) was dissolved in a mixed solvent of 30 parts monochlorobenzene and 70 parts dichloromethane.
[0054]
This paint was applied by a dipping method and dried at 120 ° C. for 2 hours to form a 30 μm charge transport layer.
[0055]
Next, evaluation will be described.
[0056]
The device used was a modified LBP “LBP-930” manufactured by Canon. The prepared electrophotographic photosensitive member was subjected to paper passing durability at 30 ° C. and 80% RH with this apparatus. The sequence was an intermittent mode that stopped once for each printed sheet.
[0057]
The toner was replenished when the toner ran out, and durability was maintained until a problem occurred in the image. The results are shown in Table 1.
[0058]
(Example 2 )
In Example 1, except that the 0.001 parts of di-methyl polysiloxane was evaluated to create the electrophotographic photosensitive member in the same manner as in Example 1. The results are shown in Table 1.
[0059]
(Comparative Example 1)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that no silicone antifoaming agent was used in the charge transport layer. The results are shown in Table 1.
[0060]
[ Table 1 ]
[0061]
(Example 3 )
A 30φ357.5 mm Al cylinder was used as a support, and a coating material composed of the following materials was applied on the support by a dipping method and thermally cured at 140 ° C. for 30 minutes to form a 15 μm conductive layer.
[0062]
Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: Titanium oxide 2 parts Binder resin: Phenol resin 6 parts Leveling material: Silicone oil 0.001 part Solvent: Methanol, methoxypropanol 0.2 / 0.8 20 copies [0063]
Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol was applied by a dipping method to form a 0.5 μm intermediate layer.
[0064]
Next, the structural formula [0065]
[Chemical 3]
[0066]
10 parts of the azo pigment, 5 parts of polyvinyl butyral (trade name ELEX BL-S: manufactured by Sekisui Chemical Co., Ltd.) and 600 parts of cyclohexanone were dispersed in a sand mill apparatus using glass beads to obtain a coating for a charge generation layer. This paint was dipped on the undercoat layer and dried at 120 ° C. for 20 minutes to obtain a 0.15 μm charge generation layer.
[0067]
Next, 6.3 parts of an amine compound having the following structural formula:
[Formula 4]
[0069]
2.7 parts of amine compound of the following structural formula
[Chemical formula 5]
[0071]
Bisphenol Z type polycarbonate resin (trade name Z-400: manufactured by Mitsubishi Gas Chemical Company) 9 parts of the present invention as a silicone anti-foaming agent according to di-methyl polysiloxane (trade name SH200: Dow Corning Toray Silicone Co., Ltd. ) 0.0002 part was dissolved in a mixed solvent of 30 parts monochlorobenzene and 20 parts dichloromethane.
[0072]
Further, a solution obtained by dispersing 2 parts of fluororesin powder (trade name: Lubron L-2: manufactured by Daikin Industries) in 10 parts of monochlorobenzene by sand mill dispersion was added to the above solution. At this time, 0.1 part of a surfactant (trade name GF-300: manufactured by Toagosei Co., Ltd.) as a dispersion aid was added to stabilize the dispersion of the powder. The charge transport coating material was dipped on the charge generation layer and dried at 120 ° C. for 2 hours to form a 28 μm thick charge transport layer.
[0073]
Next, evaluation will be described.
[0074]
The apparatus used was a modified Canon “NP-6035” copier. The prepared electrophotographic photosensitive member was subjected to paper passing durability at 30 ° C. and 80% RH with this apparatus. The intermittent mode is set to stop once for each sheet.
[0075]
(Example 4 )
In Example 3, except that the 0.001 parts of di-methyl polysiloxane was evaluated to create the electrophotographic photosensitive member in the same manner as in Example 3. The results are shown in Table 2 .
[0076]
(Comparative Example 2)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 3 except that no silicone antifoaming agent was used in the charge transport layer. The results are shown in Table 2.
[0077]
[ Table 2 ]
[0078]
【The invention's effect】
As described above, the electrophotographic photosensitive member used in the electrophotographic apparatus of the present invention has good electrical resistance against discharge by direct charging, provides a good image, has high durability, and is good for a long period of time. An image can be formed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging means 3 Image exposure means 4 Developing means 5 Paper feed means 6 Transfer means 7 Cleaning means 8 Pre-exposure means 9 Fixing means

Claims (2)

In an electrophotographic apparatus that forms an image by applying an image forming process including a step of charging the surface of the object to be charged by a charging unit to the object to be charged.
It said member to be charged is, a charge transport layer formed by the charge generating layer and a dip coating on a conductive substrate laminated in this order, a charge transport layer formed by the dip coating is a electrophotographic photoreceptor which is a surface layer And
The surface layer contains a charge transport material, a binder resin and a silicone-based antifoaming agent, the silicone-based antifoaming agent is dimethylpolysiloxane, and the content of dimethylpolysiloxane in the surface layer is 0 with respect to the binder resin. 0.002 to 0.01% by weight,
2. The electrophotographic apparatus according to claim 1, wherein the charge processing means of the charged body is a direct charging device that charges a charged body surface by bringing a charging member to which a voltage is applied into contact with the charged body.   The electrophotographic apparatus according to claim 1, wherein the surface layer contains a silicone-based antifoaming agent and a fluorine-based resin powder.