JP3740460B2 - Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus, and more specifically, an electrophotographic photosensitive member having a surface layer containing a specific resin, and a process having the electrophotographic photosensitive member. The present invention relates to a cartridge and an electrophotographic apparatus.
[0002]
[Prior art]
In the electrophotographic method, as shown in U.S. Pat. No. 2,297,691, the electrical resistance changes depending on the amount of irradiation received during image exposure, and in the dark place is a photoconductive material comprising a support coated with an insulating material. Use materials. Basic characteristics required for an electrophotographic photosensitive member using this photoconductive material are (1) that it can be charged to an appropriate potential in a dark place, (2) little potential dissipation in a dark place, and (3 ) Quickly dissipate charges by light irradiation.
[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 and 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 disadvantages 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]
Further, the organic photoconductive compound can freely select the photosensitive wavelength range of the electrophotographic photosensitive member depending on the compound. For example, in the case of an azo pigment, Japanese Patent Laid-Open Nos. 61-272754 and 56-167759 are disclosed. The gazette discloses substances having high sensitivity in the visible region, and JP-A 57-19576 and JP-A 61-228453 show compounds having sensitivity up to the infrared region. Yes.
[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 frequency of demand thereof has increased.
[0007]
Electrophotographic photoreceptors using these organic photoconductive compounds are sometimes used as functionally separated photoreceptors in which a charge transport layer and a charge generation layer are laminated in order to satisfy both electrical and mechanical properties. Many. 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 is also required.
[0009]
Specifically, electrical deterioration due to ozone and nitrogen oxides during charging, discharge during charging, mechanical deterioration in which the surface is worn or scratched by rubbing of the cleaning member, durability against electrical deterioration Is required.
[0010]
The electrical deterioration is particularly problematic in that a carrier stays in a portion irradiated with light and a potential difference occurs from a portion not irradiated with light, which occurs as a photo memory.
[0011]
Unlike the inorganic photoreceptors, organic photoreceptors that are often soft in material are inferior in durability against mechanical deterioration and are particularly desired to be improved in durability.
[0012]
Various attempts have been made to satisfy the durability characteristics required for the photoreceptor as described above.
[0013]
Polycarbonate resin with bisphenol A as a skeleton is attracting attention as a resin that is often used for the surface layer and has good wear and electrical properties. Has a point.
[0014]
(1) It has poor solubility and exhibits good solubility only in a part of halogenated aliphatic hydrocarbons such as dichloromethane and 1,2-dichloroethane, and these solvents have low boiling points. When a photoreceptor is manufactured using the prepared coating solution, the coated surface is likely to be whitened. It also takes time to manage the solid content of the coating liquid.
[0015]
(2) Solvents other than halogenated aliphatic hydrocarbons are partially soluble in tetrahydrafuran, dioxane, cyclohexanone or mixed solvents thereof, but the solution gels in several days. Inferior in properties and unsuitable for photoconductor production.
[0016]
(3) Furthermore, even if the above formulas (1) and (2) are improved, solvent cracks are likely to occur in the polycarbonate resin having bisphenol A as a skeleton.
[0017]
(4) In addition, with conventional polycarbonate resins, the film formed with the resin has no lubricity, so the photoreceptor is easily damaged, and toner fusion is used in a cleaning setting that reduces the amount of wear of the electrophotographic photoreceptor. In some cases, such as image defects such as, or cleaning defects due to early deterioration of the cleaning blade may occur.
[0018]
The solution stability mentioned in the above (1) and (2) can be solved by using a polycarbonate Z resin having a bulky cyclohexylene group as a polymer structural unit, or by copolymerizing with bisphenol Z, bisphenol C or the like. I came.
[0019]
Solvent cracks can also be solved by using silicone-modified polycarbonate or ether-modified polycarbonate, as disclosed in JP-A-6-51544 and JP-A-6-75415. However, these modified polycarbonates have a structure that is more flexible against internal stress in the polymer in order to prevent solvent cracks than conventional polycarbonate resins, resulting in the mechanical properties of the polymer body. There was a drawback that the strength decreased.
[0020]
Further, in recent years, a direct charging method in which a voltage is directly applied to a charging member and a charge is applied to an electrophotographic photosensitive member as disclosed in Japanese Patent Application Laid-Open Nos. 57-17826 and 58-40566 has become mainstream. It's getting on.
[0021]
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. Around 80% of the current flowing through the capacitor is wasted because it flows through the shield, whereas direct charging has the merit of being very economical because there is no waste.
[0022]
However, direct charging has a drawback that charging stability is very poor because of charging by discharge according to Paschen's law. As a countermeasure, a so-called AC / DC charging system in which an AC voltage is superimposed on a DC voltage has been devised (Japanese Patent Laid-Open No. 63-149668).
[0023]
Although this charging method has improved the stability during charging, the amount of discharge on the surface of the electrophotographic photosensitive member is greatly increased due to the superimposition of AC, so that the amount of abrasion of the electrophotographic photosensitive member is increased. As a result, not only mechanical strength but also electrical strength has been required.
[0024]
[Problems to be solved by the invention]
The object of the present invention is to solve the problems in the case of having a conventional polycarbonate resin as a surface layer, to have excellent solvent crack resistance without impairing mechanical strength, and to have good electric resistance by direct charging. It is an object of the present invention to provide an electrophotographic photosensitive member with little photo memory, which can be easily manufactured, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.
[0025]
[Means for Solving the Problems]
That is, the present invention is an electrophotographic photosensitive member having a photosensitive layer on a conductive support, and a contact charging means for charging the electrophotographic photosensitive member with a charging member brought into contact with the electrophotographic photosensitive member. In an electrophotographic photosensitive member for an electrophotographic apparatus having
The photosensitive layer is a photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order from the conductive support side, the surface layer of the electrophotographic photoreceptor is the charge transport layer, and the surface of the electrophotographic photoreceptor An electrophotographic photoreceptor, wherein the layer contains a polymer having a structural unit represented by the following formula (1).
[0026]
[Chemical 2]
[0031]
DETAILED DESCRIPTION OF THE INVENTION
The polymer having the structural unit represented by the formula (1) used in the present invention is usually an alkaline solution with a mixture of terephthalic acid chloride and isophthalic acid chloride to improve the solubility of the bisphenol represented by the following formula (2). Can be synthesized by interfacial polymerization by stirring in a solvent / water system.
[0032]
[Chemical 3]
[0034]
The ratio of terephthalic acid chloride to isophthalic acid chloride is determined in consideration of the solubility of the polymer, and there is no established theory. However, if any chloride is less than 30 mol%, the solubility of the synthesized polymer is extremely lowered, so care must be taken. Usually, it is preferable to synthesize at a ratio of 1/1.
[0035]
Further, a copolymer with other general bisphenols such as bisphenol Z, bisphenol A, bisphenol C, and bisphenol AF may be prepared in consideration of solubility during polymerization. However, in this case, it is preferable that the structural unit represented by the formula (1) is present in an amount of 5 to 90 mol%, more preferably 10 to 50 mol%, of the total polymer.
[0036]
The electrophotographic photosensitive member of the present invention containing a polymer having a structural unit represented by the formula (1) has particularly good electrophotographic characteristics, including solvent crack resistance, mechanical strength, and electric resistance in AC charging. It is what you have.
[0037]
The polymer having the structural unit represented by the formula (1) contains a unit having rigidity in the structural unit, and the unit is partially vitrified at the time of forming the electrophotographic photosensitive member, whereby the entire polymer film is formed. Increases durability.
[0038]
In addition, the partial vitrification inside the molecule increases the intramolecular density and combines the amorphous part and the crystalline part in the same molecule. Therefore, it is presumed that even if chemicals that cause solvent cracks enter, the internal stress is maintained and cracks do not occur.
[0039]
It is presumed that the mechanical strength becomes stronger due to the presence of the amorphous part.
[0040]
In terms of electrical resistance, molecular cleavage due to electrical degradation does not have active protons in the central skeleton, and the arylate structure, which is an ester bond of an aryl group compared to the carbonate bond, is particularly resistant to electric current due to AC charging. Is considered to have risen. The reason for this has not been confirmed, but it is presumed that the carbonate bond has oxygen atoms on both sides of the carboxy group, so that the dipole moment is large and weak against electric energy.
[0041]
Hereinafter, the structure of the electrophotographic photosensitive member used in the present invention will be described.
[0042]
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.
[0043]
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, plastics, and the like. .
[0044]
When the 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 support. This can be formed by dispersing conductive powder such as carbon black and metal particles in a binder resin. The film thickness of the conductive layer is preferably 5 to 40 μm, more preferably 10 to 30 μm.
[0045]
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 film thickness of the intermediate layer is preferably 0.05 to 5 μm, more preferably 0.3 to 1 μm.
[0046]
A charge generation layer is formed on the intermediate layer. Examples of the charge generating 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 function 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 type. It is well dispersed by a method such as a high-speed disperser, and is formed by applying and drying the dispersion. The film thickness of the charge generation layer is preferably 5 μm or less, more preferably 0.1 to 2 μm.
[0047]
The charge transport layer is formed by applying and drying a paint in which a charge transport material and a binder resin containing the polymer used in the present invention are dissolved in a solvent. Examples of the charge transport material used include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.
[0048]
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 preferably 5 to 40 μm, more preferably 15 to 30 μm.
[0049]
FIG. 1 shows a schematic configuration of an electrophotographic apparatus having a process cartridge having the electrophotographic photosensitive member of the present invention.
[0050]
In the figure, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotated about a shaft 2 in the direction of an arrow at a predetermined peripheral speed. In the rotation process, the photosensitive member 1 is uniformly charged at a predetermined positive or negative potential on its peripheral surface by the primary charging unit 3, and then from an image exposure unit (not shown) such as slit exposure or laser beam scanning exposure. The image exposure light 4 is received. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoreceptor 1.
[0051]
The formed electrostatic latent image is then developed with toner by the developing unit 5, and the developed toner developed image is rotated between the photosensitive member 1 and the transfer unit 6 from a sheet feeding unit (not shown). The image is sequentially transferred by the transfer means 6 to the transfer material 7 that is synchronously taken out and fed.
[0052]
The transfer material 7 that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means 8, and subjected to image fixing, thereby being printed out as a copy (copy).
[0053]
After the image transfer, the surface of the photoreceptor 1 is cleaned by removing the transfer residual toner by the cleaning unit 9 and further subjected to charge removal processing by the pre-exposure light 10 from the pre-exposure unit (not shown), and then repeatedly. Used for imaging. When the primary charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not always necessary.
[0054]
In the present invention, a plurality of components such as the electrophotographic photosensitive member 1, the primary charging unit 3, the developing unit 5 and the cleaning unit 9 described above are integrally coupled as a process cartridge. May be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 3, the developing unit 5, and the cleaning unit 9 is integrally supported together with the photosensitive member 1 to form a cartridge, and can be attached to and detached from the apparatus main body using guide means such as a rail 12 of the apparatus main body. The process cartridge 11 can be obtained.
[0055]
Further, when the electrophotographic apparatus is a copying machine or a printer, the image exposure light 4 is a reflected light or transmitted light from a document, or a signal is read out from a document by a sensor, and a laser beam performed according to this signal. Light emitted by scanning, LED array driving, liquid crystal shutter array driving, and the like.
[0056]
On the other hand, when used as a facsimile printer, the image exposure light 4 becomes exposure light for printing received data. FIG. 2 is a block diagram showing an example of this case.
[0057]
The controller 14 controls the image reading unit 13 and the printer 22. The entire controller 14 is controlled by the CPU 20. The read data from the image reading unit 13 is transmitted to the other station through the transmission circuit 16. Data received from the partner station is sent to the printer 22 through the receiving circuit 15. Predetermined image data is stored in the image memory. The printer controller 21 controls the printer 22. 17 is a telephone.
[0058]
An image received from the line 18 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 15, and then the image information is decoded by the CPU 20 and stored in the image memory 19 sequentially. When at least one page image is stored in the memory 19, the CPU 20 records the image of the page. The CPU 20 reads one page of image information from the image memory 19, and the printer controller 21 decodes the one page image. Send image information. When the printer controller 21 receives image information of one page from the CPU 20, the printer controller 21 controls the printer 22 to record the image information of the page. The CPU 20 receives the next page during recording by the printer 22.
[0059]
In this way, the image is received and recorded.
[0060]
The electrophotographic photosensitive member of the present invention can be used not only in electrophotographic copying machines but also widely in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.
[0061]
A description will be given below in accordance with examples. The middle part of the examples represents parts by weight.
[0062]
[Example 1]
A 30 mm, 254 mm 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 and thermally cured at 140 ° C. for 30 minutes to form a 15 μm conductive layer.
[0063]
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 [0064]
Next, a solution in which 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon were dissolved in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol was applied by dip coating, and a 0.5 μm intermediate layer was applied. Formed.
[0065]
Next, 4 parts of oxytitanium phthalocyanine (TiOPc) in which the Bragg angle 2θ ± 0.2 ° of CuKα characteristic X-ray diffraction has strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° And 2 parts of polyvinyl butyral (trade name: ESREC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were dispersed in a sand mill apparatus using φ1 mm glass beads for 4 hours, and then 100 parts of ethyl acetate was added to prepare a dispersion for charge generation layer. Prepared. This was applied by a dip coating method to form a 0.3 μm charge generation layer.
[0066]
Next, 9 parts of an amine compound of the following structural formula,
[0067]
[Formula 4]
1 part of an amine compound of the following structural formula
[Chemical formula 5]
And Example 2 in Table 2. 10 parts of the polymer shown in 1 was dissolved in a mixed solvent of 30 parts of monochlorobenzene and 70 parts of dichloromethane.
[0069]
This polymer has the formula a bisphenol (0.003 mol) and bisphenol Z needed to create a structural unit represented by (1), sodium hydroxide (0.8 g), tetramethylammonium chloride (1 g) Dissolve in 100 ml of water and put into a 1 liter mixer, and stir a solution of terephthalic acid chloride (0.005 mol) and isophthalic acid chloride (0.005 mol) in 1,2-dichloroethane (30 ml). Then, the mixture was stirred at high speed for 10 minutes and allowed to stand for 2 hours. Then, a 1,2-dichloroethane liquid was recovered, and a large amount of hexane was added to recover the polymer. In addition, after collection | recovery, what performed the purification process by water washing | cleaning, chloroform dissolution, and methanol dripping was used .
[0070]
This paint was applied by a dip coating method and dried at 120 ° C. for 2 hours to form a 25 μm charge transport layer.
[0071]
Next, evaluation will be described.
[0072]
The apparatus used was a modified Hewlett-Packard LBP "Laser Jet 4plus" (process speed 71 mm / sec). In the modification, the primary charging control is constant current control and the constant voltage control is used. The prepared electrophotographic photoreceptor was subjected to paper passing durability (HH durability) at 28 ° C. and 90% RH with this apparatus. The sequence was an intermittent mode that stopped once for each printed sheet.
[0073]
If the toner runs out, it is replenished and it lasts until there is a problem with the image. Further, it was worn for 15 minutes using a Taber abrasion tester using an abrasive tape, and the weight loss at that time was measured.
[0074]
Further, 3000 Lux, 20 minutes of white fluorescent light was applied to a part of the electrophotographic photosensitive member and left for 4 minutes, and then the bright part potential was measured to determine how much the bright part potential was lowered before the light was applied.
[0075]
Further, the solvent cracking property was defined as “X” when the sebum was attached to the surface and left for 48 hours, and the presence or absence of the solvent crack was observed by microscopic observation.
[0076]
The results are shown in Table 3.
[0077]
[Table 2]
The mixing ratio of terephthalic acid chloride and isophthalic acid chloride was 1: 1 by molar ratio. The molecular weight was measured by gel permeation chromatography.
[0079]
[Table 3]
[0080]
[Comparative Examples 1-4]
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the binder of the charge transport layer used in the conditions 1 to 4 in Table 4 was used. The results are shown in Table 5.
[0081]
[Table 4]
[0082]
[Table 5]
[0083]
【The invention's effect】
The electrophotographic photosensitive member of the present invention has excellent solvent crack resistance without impairing mechanical strength, and further has high mechanical strength and good electric resistance against discharge due to direct charging. Therefore, it is possible to provide an electrophotographic photosensitive member suitable for direct charging that is easy to perform, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus having a process cartridge having an electrophotographic photosensitive member of the present invention.
FIG. 2 is a diagram showing an example of a block diagram of a facsimile having the electrophotographic photosensitive member of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrophotographic photosensitive member 2 Axis 3 Primary charging means 4 Image exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Image fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Rail 13 Image reading unit 14 Controller 15 Reception circuit 16 Transmission circuit 17 Telephone 18 Line 19 Image memory 20 CPU
21 Printer controller 22 Printer

Claims (3)

An electrophotographic photosensitive member having a photosensitive layer on a conductive support, the electrophotographic photosensitive member having contact charging means for charging the electrophotographic photosensitive member with a charging member in contact with the electrophotographic photosensitive member In the electrophotographic photosensitive member of
The photosensitive layer is a photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order from the conductive support side, the surface layer of the electrophotographic photoreceptor is the charge transport layer, and the surface of the electrophotographic photoreceptor An electrophotographic photoreceptor, wherein the layer contains a polymer having a structural unit represented by the following formula (1).
  The electrophotographic photosensitive member according to claim 1 and a contact charging means for charging the electrophotographic photosensitive member are integrally supported by a charging member brought into contact with the electrophotographic photosensitive member. A process cartridge that is detachable.   The electrophotographic photosensitive member according to claim 1, comprising a charging unit, a charging unit, an image exposing unit, a developing unit, and a transfer unit, wherein the charging unit is brought into contact with the electrophotographic photosensitive unit by a charging member. An electrophotographic apparatus comprising a contact charging means for charging.