JPH10254161A - Electrophotographic photoreceptor, process cartridge and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor having high mechanical strength while having excellent resistance against solvent cracking, by incorporating a polyallylate resin produced from a specified bivalent carboxylic acid component and a dihydric phenol component into the surface layer of an electrophotographic photoreceptor. SOLUTION: The surface layer of this electrophotographic photoreceptor contains a polyallylate resin obtd. from a bivalent carboxylic acid component expressed by HOOC-X-COOH and a dihydric phenol component. In the formula, X is a bivalent polycyclic aromatic group or heterocyclic group which may have substituents. The polymer used can be produced by interface polymn. of the dicarboxylic acid expressed by the formula or its chloride with bisphenol in the presence of alkali while stirring in a solvent/water system. A mixture of the dicarboxylic acid expressed by the formula with terephthalic acid or isophthalic acid may be used. Thereby, the obtd. electrophotographic photoreceptor shows decreased photomemory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus. More specifically, the present invention relates to an electrophotographic photosensitive member 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 U.S. Pat.
As shown in JP-A No. 1 (1993), a photoconductive material comprising a support coated with an insulating substance is used in which the electric resistance changes in accordance with the amount of irradiation received during image exposure, and in a dark place. The basic characteristics required of an electrophotographic photoreceptor using this photoconductive material are (1) that it can be charged to an appropriate potential in a dark place, (2) that the potential is less dissipated in a dark place, and (3) And (3) quickly dissipating the charge by light irradiation.

[0003] Conventionally, selenium,
Inorganic photoreceptors having a photosensitive layer mainly containing an inorganic photoconductive compound such as zinc oxide and cadmium sulfide have been widely used. However, these satisfies the conditions (1) to (3), but are not necessarily satisfactory in thermal stability, moisture resistance, durability and productivity.

In order to overcome the disadvantages of inorganic photoconductors, electrophotographic photoconductors containing various organic photoconductive compounds as main components have been actively developed in recent years. For example, US Pat.
No. 851 describes a photoreceptor having a charge transporting layer containing triallylpyrazolin, and US Pat. No. 3,871,880 discloses a photogenerating layer comprising a derivative of perylene pigment and 3
Photoreceptors comprising a charge transport layer comprising a condensate of propylene and formaldehyde are known.

Further, the organic photoconductive compound can freely select the photosensitive wavelength range of the electrophotographic photosensitive member depending on the compound.
JP-A Nos. 2754 and 56-167759 disclose substances exhibiting high sensitivity in the visible region, and JP-A-57-19576 and JP-A-61-22.
No. 8453 discloses a compound having sensitivity up to the infrared region.

[0006] Of these materials, those exhibiting sensitivity in the infrared region are used in laser beam printers (hereinafter abbreviated as LBPs) and LED printers, which have been remarkably advanced in recent years, and the demand frequency thereof is increasing.

Electrophotographic photoreceptors using these organic photoconductive compounds are used as function-separated type photoreceptors in which a charge transport layer and a charge generation layer are laminated in order to satisfy both electrical and mechanical properties. In many cases. On the other hand, it is needless to say that the electrophotographic photoreceptor is required to have sensitivity, electrical characteristics, and even optical characteristics according to the electrophotographic process applied.

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

Specifically, electrical deterioration due to ozone and nitrogen oxides during charging, mechanical deterioration in which the surface is worn or scratched due to discharge during charging, and rubbing of the cleaning member, and electrical deterioration Durability is required.

[0010] The electrical degradation is particularly problematic in that a carrier stays in a portion irradiated with light and a potential difference is generated from a portion not irradiated with light, and this phenomenon occurs as a photo memory.

[0011] Unlike an inorganic photoreceptor, an organic photoreceptor, which is often soft in material, is inferior in durability against mechanical deterioration and is particularly demanded to improve durability.

Various attempts have been made to satisfy the durability characteristics required for the photoreceptor as described above.

As a resin often used for the surface layer and having good abrasion and electric properties, a polycarbonate resin having bisphenol A as a skeleton has been attracting attention. However, not all of the above-mentioned problems can be solved, and the following problems cannot be solved. It has such problems.

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

(2) Solvents other than halogenated aliphatic hydrocarbons are partially soluble in tetrahydrafuran, dioxane, cyclohexanone or a mixed solvent thereof, but the solution gels in a few days. Inferior aging,
It is not suitable for photoconductor production.

(3) Further, even if the above formulas (1) and (2) are improved, solvent cracks are liable to occur in the polycarbonate resin having bisphenol A as a skeleton.

(4) In addition, in the case of a conventional polycarbonate resin, the coating formed of the resin does not have lubricity, so that the photoreceptor is easily damaged, and the cleaning setting for reducing the abrasion loss of the electrophotographic photoreceptor is difficult. In some cases, image defects such as toner fusion occur, or cleaning failure or toner fusion occurs due to early deterioration of the cleaning blade.

For the solution stability mentioned in the above (1) and (2), use of a polycarbonate Z resin having a bulky cyclohexylene group as a structural unit of the polymer, or copolymerization with bisphenol Z or bisphenol C, etc. 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 There was a disadvantage that the strength was reduced.

Further, in recent years, a direct charging system disclosed in JP-A-57-17826 and JP-A-58-40566, in which a voltage is applied directly to a charging member and a charge is applied 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 brought into direct contact with an electrophotographic photosensitive member to apply an electric charge. The scorotron generates a significantly smaller amount of ozone than a scorotron or the like. While about 80% of the current flowing through the charger flows through the shield, it is wasted, whereas direct charging has the advantage that it is very economical without this waste.

However, direct charging has a disadvantage that charging stability is very poor because of charging by discharge according to Paschen's rule. As a countermeasure, a so-called AC / DC charging method in which an AC voltage is superimposed on a DC voltage has been devised (Japanese Patent Application Laid-Open No. 63-149668).

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 superposition of AC, so that the amount of scraping of the electrophotographic photosensitive member increases. A new drawback has arisen, requiring not only mechanical strength but also electrical strength.

[0024]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems when a conventional polycarbonate resin is used as a surface layer, to have excellent mechanical strength while having excellent solvent cracking resistance, and to directly charge. An object of the present invention is to provide an electrophotographic photoreceptor which has good electric resistance characteristics with respect to and a small photo memory, a process cartridge having the electrophotographic photoreceptor, and an electrophotographic apparatus.

[0025]

That is, the present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the surface layer of the electrophotographic photosensitive member is represented by the following formula (1): An electrophotographic photoreceptor comprising a polyarylate resin obtained from a polycarboxylic acid component and a dihydric phenol component.

HOOC-X-COOH (1) (wherein, X represents a divalent polynuclear aromatic group or heterocyclic group which may be substituted.) The present invention also includes the above electrophotographic photoreceptor. A process cartridge and an electrophotographic apparatus.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of the divalent carboxylic acid (dicarboxylic acid) component represented by the formula (1) are shown in Tables 1 and 2, but are not limited thereto.

[0028]

[Table 1]

[0029]

[Table 2]

In Table 1, preferred examples include structural unit examples (1-1), (1-2) and (1-3), and in particular, structural units (1-1) and (1-2). preferable.

In Table 2, preferred examples include structural unit examples (2-3), (2-5) and (2-7), and in particular, structural unit (2-5) and (2-7). preferable.

The polymer used in the present invention can be synthesized by interfacial polymerization of a dicarboxylic acid represented by the following formula (1) or a chloride thereof with a bisphenol and an alkali in a solvent / water system under stirring.

The dicarboxylic acid may be used as a mixture of the following formula (1) and terephthalic acid and isophthalic acid.

HOOC-X-COOH (1) (wherein, X represents an optionally substituted divalent polynuclear aromatic group or heterocyclic group.) The ratio of terephthalic acid to isophthalic acid is determined by dissolving the polymer. It is determined in consideration of the nature, and there is no established theory for the introduction ratio.

Since the dicarboxylic acid represented by the formula (1) sometimes produces a polymer which is too rigid, it is necessary to consider the ratio of the dicarboxylic acid in consideration of not only solubility but also film strength.

Further, as the dicarboxylic acid component, 3-te
Polymerization can also be performed using a compound having a substituent such as rtbutyl isophthalic acid.

The bisphenol used in the present invention is represented by the following general formula (2).

[0038]

Embedded image (Wherein, X represents a single bond, —O—, —S—, —SO—, an alkylene group, a cycloalkylene group or a siloxane group which may be substituted, and R _{1 to} R ₈ represent a hydrogen atom, a halogen atom, In the electrophotographic photoreceptor of the present invention, even if the bisphenol component is a polymer composed of the same compound represented by the formula (2), two or more compounds represented by the formula (2) Copolymers composed of different types of constituent units shown in 2) may be used.

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

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

The polymer according to the present invention contains a unit having rigidity in its constituent unit, and the unit is partially vitrified at the time of forming an electrophotographic photosensitive member, thereby increasing the durability of the entire polymer film. is there.

Further, the intramolecular density is increased by the partial vitrification inside the molecule, and since the amorphous portion and the crystalline portion are combined in the same molecule, the intramolecular stress generated at the time of forming the coating film can be reduced. It is presumed that even if a chemical causing a solvent crack enters, the internal stress is maintained and no crack occurs.

It is presumed that the mechanical strength is enhanced by the presence of the crystalline portion.

With respect to the electric resistance, it seems that the durability against electric deterioration is increased by the influence of the polynuclear aromatic ring group or the heterocyclic group, but the details are unknown. Further, it is considered that the arylate structure in which molecular cleavage due to electrical deterioration is an ester bond of an aryl group is more resistant to electric current due to AC charging than the carbonate bond, and the electric resistance is particularly improved. Although the reason for this has not been confirmed, it is assumed that the carbonate bond has a large dipole moment due to oxygen atoms on both sides of the carboxy group and is weak against electric energy.

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

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

The conductive support to be used only needs to have conductivity, such as a metal such as aluminum and stainless steel.
Alternatively, metal, paper, plastic, or the like provided with a conductive layer may be used, and examples of the shape include a sheet shape and a cylindrical shape.

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 scratch 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
４０40 μm is preferable, and more preferably 10-30 μm
It is.

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 applied by dissolving in an appropriate solvent.
The thickness of the intermediate layer is preferably from 0.05 to 5 μm, more preferably from 0.3 to 1 μm.

The 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, anthantrone, dibenzapyrene quinone, trisazo, cyanine, disazo, monoazo, indigo, quinacridone, and asymmetric quinocyanine pigments. Can be In the case of the function-separated type, the charge generating layer is formed by mixing the charge generating substance with a binder resin and a solvent in an amount of 0.3 to 4 times the amount of a homogenizer, an ultrasonic dispersion, a ball mill, a vibration ball mill, a sand mill, an attritor, a roll mill, and a liquid collision type high speed. It is well dispersed by a method such as a dispersing machine, and is formed by applying and drying a dispersion. 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 formed by applying and drying a coating material in which a charge transport material and a binder resin containing a polymer used in the present invention are dissolved in a solvent. Examples of the charge transport material used include a triarylamine compound, a hydrazone compound, a stilbene compound, a pyrazoline compound, an oxazole compound, a triallylmethane compound, and a thiazole compound.

These are combined with 0.5 to 2 times the amount of the binder resin, applied and dried to form a charge transport layer. The thickness of the charge transport layer is preferably from 5 to 40 μm, more preferably from 15 to 30 μm.

The following is a description of the embodiment. The middle part in the examples indicates parts by weight. [Example 1] A 30φ, 254mm aluminum cylinder was used as a support, and a coating composed of the following materials was applied on the support by dip coating at 140 ° C.
For 30 minutes to form a 15 μm conductive layer.

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 obtained 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 thereon by dip coating. Was formed.

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

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

[0058]

Embedded image 1 part of amine compound of the following structural formula

[0059]

Embedded image And 10 parts of the polymer described in Condition 1 in Table 3 were dissolved in a mixed solvent of 30 parts of monochlorobenzene and 70 parts of dichloromethane.

This polymer was synthesized according to the following procedure.

Bisphenol C (0.003 mol),
Bisphenol A (0.003 mol), sodium hydroxide (0.8 g) and tetramethylammonium chloride (1 g) were dissolved in 100 ml of water and charged into a 1 liter mixer, to which 1,2-dichloroethane (30 g) was added.
ml), chloride of 2,6-naphthalenedicarboxylic acid {Structural unit example (1-1) in Table 1 above) (0.003 mol)
l), a solution in which terephthalic acid chloride (0.0015 mol) and isophthalic acid chloride (0.0015 mol) were dissolved was added with stirring, and the mixture was stirred at high speed for 10 minutes. After leaving for 2 hours, a 1,2-dichloroethane solution was recovered, and a large amount of hexane was added to the solution to recover the polymer. In addition, the thing which performed the purification process by water washing | cleaning, methanol washing | cleaning, chloroform dissolution, and methanol dripping after collection | recovery was used. The final yield was 72%.

This paint was applied by the dip coating method.
After drying at 20 ° C. for 2 hours, a 25 μm charge transport layer was formed.

Next, the evaluation will be described.

The device is a Hewlett-Packard LBP
"Laser jet 4plus" (process speed 7
1 mm / sec). In the remodeling, primary charging was controlled by constant current control and constant voltage control. The prepared electrophotographic photosensitive member was subjected to paper passing durability (HH durability) at 28 ° C. and 95% RH using this apparatus. The sequence was an intermittent mode in which the print was stopped once for each print.

When the toner ran out, the toner was replenished and the image was durable until a problem occurred in the image.

A 15-minute abrasion was performed using a Taber abrasion tester using a polishing tape, and the weight loss at that time was measured.

Further, 3000 L of a part of the electrophotographic photosensitive member is used.
ux, exposed to the light of a white fluorescent lamp for 10 minutes, allowed to stand for 15 minutes, measured the bright portion potential, measured how much the bright portion potential had decreased before applying the light, and determined the photo memory value.

Further, regarding the solvent cracking property, sebum was adhered to the surface and allowed to stand for 72 hours, and the presence or absence of solvent cracking was observed by microscopic observation.

Table 4 shows the results.

[0070]

[Table 3]

Examples 2 to 10 Electrophotographic photosensitive members were prepared and evaluated in the same manner as in Example 1 except that the binder resin for the charge transport layer used was one of the conditions 2 to 10 shown in Table 3. Table 4 shows the results.

[0072]

[Table 4]

Examples 11 to 20 Electrophotographic photosensitive members were prepared and evaluated in the same manner as in Example 1, except that the binder resin of the charge transport layer used was one of the conditions 1 to 10 shown in Table 5. Table 6 shows the results.

The polymer described in Condition 1 in Table 5 was synthesized according to the following procedure.

Bisphenol C (0.003 mol),
Bisphenol A (0.003 mol), sodium hydroxide (0.8 g) and tetramethylammonium chloride (1 g) were dissolved in 100 ml of water and charged into a 1 liter mixer, into which 1,2-dichloroethane (30 g) was added.
ml), chloride (0.003 mol), terephthalic acid chloride (0.0015 mol) and isophthalic acid chloride (0.0015 mol) of the compound represented by Structural Unit Example (2-3) in Table 2 are dissolved in The mixture was added with stirring and stirred at high speed for 10 minutes. After leaving for 2 hours,
A dichloroethane solution was recovered, and a large amount of hexane was added thereto to recover the polymer. In addition, the thing which performed the purification process by water washing | cleaning, methanol washing | cleaning, chloroform dissolution, and methanol dripping after collection | recovery was used. The final yield was 68%.

[0076]

[Table 5]

[0077]

[Table 6]

[Comparative Examples 1 to 5] An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the binder resin of the charge transport layer used was one of the conditions 1 to 5 shown in Table 7. Table 8 shows the results.

[0079]

[Table 7]

[0080]

[Table 8]

The electrophotographic photoreceptor of the present invention has excellent solvent cracking resistance without impairing the mechanical strength, has high mechanical strength, and has good electric resistance against discharge due to direct charging. In addition, it has become possible to provide an electrophotographic photosensitive member having reduced photo memory, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

[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.

DESCRIPTION OF THE SYMBOLS 1 Electrophotographic photoreceptor of the present invention 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

Claims (5)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the surface layer of the electrophotographic photoreceptor comprises a divalent carboxylic acid component and a dihydric phenol component represented by the following formula (1). An electrophotographic photosensitive member containing the obtained polyarylate resin. HOOC-X-COOH (1) (wherein, X represents an optionally substituted divalent polynuclear aromatic group or heterocyclic group.) 2. The electrophotographic photoconductor according to claim 1, wherein the divalent carboxylic acid component is a mixture of the divalent carboxylic acid component of the formula (1) and another divalent carboxylic acid component. 3. The electrophotographic photoreceptor according to claim 1, wherein the other divalent carboxylic acid component is one or both of terephthalic acid which may be substituted and isophthalic acid which may be substituted. 4. An electrophotographic apparatus main body which integrally supports at least one member selected from the group consisting of an electrophotographic photosensitive member according to claim 1 and a charging device, a developing device and a cleaning device. A process cartridge which is detachably mounted on a process cartridge. 5. 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.