JP3402960B2 - Electrophotographic photoreceptor, process cartridge and electrophotographic apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor, and more specifically, an electrophotographic photoreceptor having a surface layer containing a specific resin, and The present invention relates to a process cartridge having an electrophotographic photosensitive member and an electrophotographic apparatus.

[0002]

2. Description of the Related Art An electrophotographic method is disclosed in US Pat. No. 229769.
As shown in Japanese Patent Laid-Open No. 1, a photoconductive material is used which comprises a support whose electric resistance changes according to the amount of irradiation received during image exposure and which is coated with an insulating material in a dark place. The basic characteristics required for an electrophotographic photosensitive member using this photoconductive material are (1) being able to be charged to an appropriate potential in a dark place, (2) having a small potential dissipation in a dark place, and (3) ) Promptly dissipating the charge by light irradiation and the like.

Conventionally, selenium has been used as an electrophotographic photoreceptor.
Inorganic photoreceptors having a photosensitive layer containing an inorganic photoconductive compound such as zinc oxide and cadmium sulfide as a main component have been widely used. However, although these satisfy the above conditions (1) to (3), they are not always satisfactory in thermal stability, moisture resistance, durability and productivity.

In recent years, electrophotographic photoreceptors containing various organic photoconductive compounds as main components have been actively developed in order to overcome the drawbacks of inorganic photoreceptors. For example, US Pat.
No. 851 discloses a photoreceptor having a charge transport layer containing triallylpyrazoline, and US Pat. No. 3,871,880 discloses a charge generation layer comprising a derivative of a perylene pigment and 3
A photoconductor or the like comprising a charge transport layer made of a condensation product of propylene and formaldehyde is known.

Further, the organic photoconductive compound can freely select the photosensitive wavelength region of the electrophotographic photosensitive member depending on the compound. For example, in the case of an azo pigment, it is disclosed in JP-A-61-27.
2754 and JP-A-56-167759 disclose substances having high sensitivity in the visible region, and JP-A-57-19576 and JP-A-61-22.
Japanese Patent No. 8453 discloses compounds having sensitivity in the infrared region.

Of these materials, those exhibiting sensitivity in the infrared region are used in laser beam printers (hereinafter abbreviated as LBP) and LED printers, which have made remarkable progress in recent years, and their demand frequency is increasing.

Electrophotographic photoreceptors using these organic photoconductive compounds are used as function-separated photoreceptors in which a charge transport layer and a charge generating layer are laminated in order to satisfy both electrical and mechanical characteristics. Often. 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 electrophotographic process applied.

Particularly in an electrophotographic photosensitive member that is repeatedly used, an electric or mechanical external force such as corona or direct charging, image exposure, toner development, transfer process and surface cleaning is directly applied to the surface of the electrophotographic photosensitive member. For,
Durability against them is also required.

Specifically, electrical deterioration due to ozone and nitrogen oxides at the time of charging, mechanical deterioration at the time of charging at the time of discharging, rubbing of a cleaning member and scratches on the surface, and electrical deterioration. Durability is required.

The electrical deterioration is particularly problematic in that carriers are retained in the light-irradiated portion and a potential difference is generated between the light-irradiated portion and the light-unirradiated portion, which occurs as a photo memory.

Organic photoreceptors, which are different from inorganic photoreceptors and are often soft in terms of material, have poor durability against mechanical deterioration and are particularly eagerly desired to have improved durability.

Various attempts have been made to satisfy the durability characteristics required for the above-mentioned photoreceptor.

Polycarbonate resin having bisphenol A as a skeleton has been attracting attention as a resin which is often used for the surface layer and has good wear properties and electric characteristics. However, it is not possible to solve all the problems mentioned above and It has such a problem.

(1) It has poor solubility and shows good solubility only in a part of halogenated aliphatic hydrocarbons such as dichloromethane and 1,2-dichloroethane, and these solvents have a low boiling point. When a photoconductor is manufactured using a coating solution prepared with the above solvent, the coated surface is easily whitened. It also takes time to manage the solid content of the coating liquid.

(2) For solvents other than halogenated aliphatic hydrocarbons, it is partially soluble in tetrahydrafuran, dioxane, cyclohexanone or a mixed solvent thereof, but the solution gels in a few days. Is inferior in aging,
Not suitable for photoconductor manufacturing.

(3) Further, 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.

(4) In addition, in the conventional polycarbonate resin, since the coating formed by the resin has no lubricity, the photoconductor is easily scratched, and the cleaning setting is set to reduce the abrasion amount of the electrophotographic photoconductor. Image defects such as toner fusion may occur, and cleaning failure or toner fusion may occur due to early deterioration of the cleaning blade.

Regarding the solution stability mentioned in the above (1) and (2), a polycarbonate Z resin having a bulky cyclohexylene group as a structural unit of the polymer is used, or it is copolymerized with bisphenol Z or bisphenol C. Has been solved by.

Solvent cracks can also be solved by using a siloxane-modified polycarbonate or an ether-modified polycarbonate as disclosed in JP-A-6-51544 and JP-A-6-75415. . However, compared to conventional polycarbonate resins, these modified polycarbonates have a structure that has flexibility against internal stress in the polymer in order to prevent solvent cracks, and as a result, the mechanical properties of the polymer body are reduced. There was a drawback that the strength was reduced.

Further, in recent years, a direct charging system as disclosed in JP-A-57-17826 and JP-A-58-40566, in which a voltage is directly applied to a charging member to apply a charge to an electrophotographic photosensitive member. Is becoming mainstream.

This is a method in which a roller-shaped charging member made of a conductive rubber or the like is directly brought into contact with an electrophotographic photosensitive member to apply an electric charge, and the amount of ozone generated is much smaller than that of a scorotron. About 80% of the current passed through the charger is wasted because it flows through the shield, whereas direct charging has the merit that it is very economical without this wasted amount.

However, the direct charging has a drawback that the charging stability is very poor because it is charged by the discharge according to Paschen's law. As a countermeasure against this, 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).

Although this charging method improves the stability during charging, the amount of discharge on the surface of the electrophotographic photosensitive member is greatly increased due to the superposition of AC, and the scraped amount of the electrophotographic photosensitive member is increased. New defects have arisen, and not only mechanical strength but also electrical strength is required.

[0024]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems of having a conventional polycarbonate resin as a surface layer, to have excellent solvent crack resistance, strong mechanical strength, and direct An object of the present invention is to provide an electrophotographic photosensitive member that has good electric resistance characteristics due to charging and is easy to manufacture.

[0025]

Means for Solving the Problems That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer on an electroconductive substrate, constituting the surface layer of the electrophotographic photosensitive member, represented by the following formula (2) An electrophotographic photosensitive member characterized by containing a polymer having units.

[0026]

[Chemical 2]

(In the formula, R _{21 to} R ₂₄ are —CH ₂ —CH═C.
H ₂ , a hydrogen atom, a halogen atom, an optionally substituted alkyl group, a cycloalkyl group, an aryl group or an aralkyl group is shown, at least one of R _{21 to} R ₂₄ is an allyl group, and R _{25 to} R ₄₀ are A hydrogen atom, a halogen atom, an optionally substituted alkyl group, a cycloalkyl group, an aryl group or an aralkyl group is shown. p, q, r and s are integers of 0 or 1, p + q ≧ 1, r + s ≧ 1 , p + q + r
+ S ≦ 3 . ) Further, the present invention is a process cartridge and an electrophotographic apparatus, each of which has the electrophotographic photosensitive member.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION In the formula (2), examples of the halogen atom include a fluorine atom, chlorine atom and bromine atom, and examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group and a butyl group. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group, examples of the aryl group include a phenyl group, a naphthyl group and an anthryl group, and examples of the aralkyl group include a benzyl group and a phenethyl group. Examples of the substituent that may be mentioned include the above-mentioned halogen atom, alkyl group and aryl group.

Specific examples of the structural unit represented by the formula (2) are shown in Table 2, but not limited to these.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

In Table 2, preferred examples are the structural unit examples 2-1, 2-2, 2-3 and 2-5, and the structural unit examples 2-1 and 2-5 are particularly preferred.

The polymer having the constitutional unit represented by the formula (2) used in the present invention is a mixture of terephthalic acid chloride and isophthalic acid chloride in order to increase the solubility of bisphenol represented by the following formula (4). And can be synthesized by interfacial polymerization with stirring in a solvent / water system under alkali.

The ratio of terephthalic acid chloride and isophthalic acid chloride is determined in consideration of the solubility of the polymer, and there is no established theory. However, either chloride is 30mo
It is necessary to note that the solubility of the synthesized polymer is extremely lowered when the content is 1% or less. Usually, it is preferable to synthesize at a ratio of 1/1.

[0038]

[Chemical 3]

(In the formula, R _{21 to} R ₂₄ are —CH ₂ —CH═C.
H ₂ , a hydrogen atom, a halogen atom, an optionally substituted alkyl group, a cycloalkyl group, an aryl group or an aralkyl group is shown, at least one of R _{21 to} R ₂₄ is an allyl group, and R _{25 to} R ₄₀ are A hydrogen atom, a halogen atom, an optionally substituted alkyl group, a cycloalkyl group, an aryl group or an aralkyl group is shown. p, q, r and s are integers of 0 or 1, p + q ≧ 1, r + s ≧ 1 , p + q + r
+ S ≦ 3 . ) In the formula (4), a halogen atom,
Specific examples of the alkyl group, cycloalkyl group, aryl group and aralkyl group, and examples of the substituent which these groups may have are the same as the specific examples in the formula (2).

In the electrophotographic photosensitive member of the present invention, even a polymer composed of the same constituent unit represented by the formula (2) is composed of two or more kinds of different constituent units represented by the formula (2). It may be a copolymer.

Further, a copolymer may be formed with other general bisphenols such as bisphenol Z, bisphenol A, bisphenol C and bisphenol AF in consideration of solubility at the time of polymerization. However, in this case, the constitutional unit represented by the formula (2) is 20 to 99 mol% of the total polymer.
It is preferably present, more preferably 50-99 mo
1%.

The electrophotographic photosensitive member according to the present invention has particularly excellent solvent crack resistance, mechanical strength, and electric resistance characteristics under AC charging, and has good electrophotographic characteristics.

The polymer according to the present invention has an allyl group in the constitutional unit, and has a three-dimensional network and is durable by being heated and condensed during the formation of the electrophotographic photosensitive member.

Due to this three-dimensionalization, it is presumed that even if a chemical which causes a solvent crack enters, the internal stress is maintained and the crack does not occur.

The mechanical strength is strengthened by taking a three-dimensional structure, and the same is done with a polycarbonate resin, which is disclosed in JP-A-5-323630.

In terms of electric resistance, even if molecular breakage due to electrical deterioration occurs due to three-dimensionalization, a sudden decrease in film strength does not easily occur. Furthermore, as compared with a carbonate bond, an ester bond of an aryl group is a current caused by AC charging. Strong and especially resistant to electricity. Although the reason for this has not been confirmed, it is presumed that the carbonate bond has a large dipole moment due to the presence of oxygen atoms on both sides of the carboxy group and is weak against electric energy.

The constitution of the electrophotographic photosensitive member used in the present invention will be described below.

The electrophotographic photosensitive member of the present invention may be a single layer type in which the photosensitive layer contains the charge transport material and the charge generating material in the same layer, or a laminated type in which the charge transport layer and the charge generating layer are separated. Although it is good, the laminated type is preferable in terms of electrophotographic characteristics.

The conductive support to be used may be one having conductivity, and a metal such as aluminum or stainless steel,
Alternatively, a metal, paper, plastic, or the like provided with a conductive layer may be used, and the shape may be a sheet shape, a cylindrical shape, or the like.

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 scratches on the support. 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
〜40μm is preferred, more preferably 10 ~ 30μm
Is.

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 dissolved in a suitable solvent and applied.
The thickness of the intermediate layer is preferably 0.05 to 5 μm, more preferably 0.3 to 1 μm.

A charge generation layer is formed on the intermediate layer.
Examples of the charge generating substance used in the present invention include selenium-tellurium, pyrylium, thiapyrylium dyes, phthalocyanine, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone and asymmetric quinocyanine pigments. To be In the case of the function-separated type, the charge generation layer includes a homogenizer, ultrasonic dispersion, ball mill, vibrating ball mill, sand mill, attritor, roll mill, and liquid collision type together with 0.3 to 4 times the amount of the charge generation material as the binder resin and solvent. Disperse well using a method such as a high-speed disperser, and apply the dispersion.
It is formed by drying. The thickness of the charge generation layer is preferably 5 μm or less, more preferably 0.1 to 2 μm.

The charge transport layer is mainly formed by coating 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.

These are combined with 0.5 to 2 times the amount of binder resin and 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.

Further, in the polymer having the constitutional unit represented by the formula (2) contained in the surface layer of the electrophotographic photoreceptor constituting the present invention, the crosslinking reaction by the allyl group of the polymer is sufficiently conducted. In order to do so, heating, light irradiation with ultraviolet rays or the like, electron beam irradiation, or the like can be performed during drying. At this time, various suitable polymerization initiators can be used to accelerate the reaction.

FIG. 1 shows a schematic structure of an electrophotographic apparatus having a process cartridge having the electrophotographic photosensitive member of the present invention.

In the figure, reference numeral 1 is a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven around a shaft 2 in a direction of an arrow at a predetermined peripheral speed. The photoconductor 1 rotates during the rotation process.
The peripheral surface of the primary charging means 3 is uniformly charged with a predetermined positive or negative potential, and then image exposure light 4 from an image exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoconductor 1.

The formed electrostatic latent image is then developed by the developing means 5.
The toner-developed image is developed by the toner, and the developed toner-developed image is taken out from a paper feeding unit (not shown) between the photoconductor 1 and the transfer means 6 in synchronization with the rotation of the photoconductor 1 and fed to the transfer material 7, The images are sequentially transferred by the transfer means 6.

The transfer material 7 having undergone the image transfer is separated from the surface of the photoconductor and introduced into the image fixing means 8 to undergo the image fixing, so that it is printed out to the outside of the apparatus as a copy.

The surface of the photoconductor 1 after the image transfer is cleaned by the cleaning means 9 by removing the transfer residual toner, and further pre-exposure light 10 from pre-exposure means (not shown).
It is used for repeated image formation after being neutralized by. If the primary charging means 3 is a contact charging means using a charging roller or the like, pre-exposure is not always necessary.

In the present invention, among the above-mentioned electrophotographic photosensitive member 1, primary charging means 3, developing means 5, cleaning means 9 and the like, a plurality of components are integrally combined as a process cartridge, The process cartridge may be detachably attached to the main body of the electrophotographic apparatus such as a copying machine or a laser beam printer. For example, a process in which at least one of the primary charging unit 3, the developing unit 5, and the cleaning unit 9 is integrally supported with the photoconductor 1 to form a cartridge, and the cartridge can be attached to and detached from the apparatus main body by using a guide unit such as a rail 12 of the apparatus main body. It can be the cartridge 11.

When the electrophotographic apparatus is a copying machine or a printer, the image exposure light 4 is reflected light or transmitted light from the original, or the original is read by a sensor, converted into a signal, and the image exposure is performed according to this signal. Laser beam scanning,
It is the light emitted by the driving of the LED array and the driving of the liquid crystal shutter array.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines but also in laser beam printers, C
It can be widely used in electrophotographic application fields such as RT printers, LED printers, liquid crystal printers, and laser plate making.

A description will be given below according to an embodiment. The middle part of an Example represents a weight part. [Example 1 3 ] An aluminum cylinder having a diameter of 30 mm and a diameter of 254 mm was used as a support, and a coating material composed of the following materials was applied to the support by a dip coating method and heat-cured at 140 ° C. for 30 minutes to obtain a conductive material of 15 μm. Layers were formed.

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 parts Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymerized nylon in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol was applied onto this by a dip coating method. An intermediate layer of 0.5 μm was formed.

Next, oxytitanium phthalocyanine (TiOPc) having strong peaks at Bragg angles 2θ ± 0.2 ° of CuKα characteristic X-ray diffraction of 9.0 °, 14.2 °, 23.9 ° and 27.1 °. ) 4 parts and 2 parts of polyvinyl butyral (trade name: S-REC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone are dispersed for 4 hours in a sand mill using φ1 mm glass beads, and then 100 parts of ethyl acetate are added to form a charge generation layer. A dispersion was prepared.
This was applied by a dip coating method to form a charge generation layer having a thickness of 0.3 μm.

Next, 9 parts of an amine compound having the following structural formula,

[0068]

[Chemical 4]

1 part of an amine compound having the following structural formula

[0070]

[Chemical 5] And 10 parts of the polymer described in Condition 1 of Table 7 were dissolved in a mixed solvent of 30 parts of monochlorobenzene and 70 parts of dichloromethane. Apply this paint by dip coating method,
It was dried at 0 ° C. for 2 hours to form a 25 μm charge transport layer.

Next, the evaluation will be described.

The apparatus is Hewlett-Packard LBP
"Laser Jet 4 plus" (Process speed 7
1 mm / sec) was modified and used. In the modification, the constant current control was used for the primary charging control and the constant voltage control was used. The produced electrophotographic photosensitive member was subjected to paper passing durability at 28 ° C. and 90% RH with this apparatus. The sequence is set to an intermittent mode in which the printing is stopped once for each sheet.

If the toner was used up, the toner was replenished and the image was durable until problems occurred.

Further, a taper abrasion tester using an abrasive tape was used for abrasion for 15 minutes, and the weight loss at that time was measured.

Further, regarding the solvent crack property, sebum was adhered to the surface and left for 48 hours, and the presence or absence of solvent cracks was observed by microscopic observation.

The results are shown in Table 8 . Except for using those conditions 2-12 in Table 7 in the binder of Example 1 4-24] charge transport layer were evaluated to create the electrophotographic photosensitive member in the same manner as in Example 1 3. The results are shown in Table 8.

[0077] Note that the photo-memory, 3000L in a part of the electrophotographic photosensitive member in the evaluation of Example 1 3
ux was irradiated with light from a white fluorescent lamp for 10 minutes, left for 10 minutes, and then the light potential was measured to determine how much the light potential had dropped before the light was applied to obtain a photomemory value.

[0078]

[Table 6]

[0079]

[Table 7]

[0080] except for using those from Comparative Example 5-8] Conditions 1 of Table 9 in the binder of the charge transport layer 4 was evaluated to create the electrophotographic photosensitive member in the same manner as in Example 1 3. The results are shown in Table 10.

[0081]

[Table 8]

[0082]

[Table 9]

[0083]

EFFECTS OF THE INVENTION According to the present invention, it has excellent solvent crack resistance without impairing mechanical strength, has good electric resistance property against discharge by direct charging, and is suitable for direct charging which is easy to manufacture. It has become possible to provide an electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

[Brief description of 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.

[Explanation of symbols] 1 Electrophotographic photoreceptor of the present invention 2 axes 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 rails

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Anayama Inventor Hideki Anayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-6-75391 (JP, A) JP-A-7 -333867 (JP, A) JP 2-254459 (JP, A) JP 8-179522 (JP, A) JP 62-135840 (JP, A) JP 7-92701 (JP, A) ) JP-A-5-323630 (JP, A) JP-A-9-216944 (JP, A) JP-A-9-160264 (JP, A) JP-A-8-95263 (JP, A) JP-A-6- 273949 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the surface layer of the electrophotographic photoreceptor contains a polymer having a structural unit represented by the following formula (2). Characteristic electrophotographic photoreceptor. [Chemical 1] (In the formula, R _{21 to} R _{24 each} represent —CH ₂ —CH═CH ₂ , a hydrogen atom, a halogen atom, an optionally substituted alkyl group, a cycloalkyl group, an aryl group or an aralkyl group,
At least one of R _{21 to} R ₂₄ is an allyl group, and R ₂₅ to
R ₄₀ represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. p, q, r and s are integers of 0 or 1 and p + q ≧ 1, r + s ≧ 1 and p + q + r + s ≦ 3 . ) 2. The electrophotographic photosensitive member according to claim 1, and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means are integrally supported, and are detachably attached to the main body of the electrophotographic apparatus. Process cartridge characterized in that. 3. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an image exposing unit, a developing unit, and a transferring unit.