JP2001075295A - Method of regenerating electrophotographic photoreceptor and regenerated electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for regenerating an electrophotographic photoreceptor by which a used electrophotographic photoreceptor can be regenerated to save material, and reduce waste product so that resources can be protected at a low cost by a simple and easy method and to obtain a electrophotographic photoreceptor regenerated by the method. SOLUTION: As to this method of regenerating the electrophotographic photoreceptor, and the regenerated electrophotographic photoreceptor regenerated by the method; a photoreceptive layer is removed from the used electrophotographic photoreceptor constituted of at least the photoreceptive layer on the surface of a conductive base body by accurate grinding so that the range of the film thickness fluctuation obtained after grinding is <=±1 μm while leaving the photoreceptive layer having a specified film thickness, and then a new surface layer is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of reproducing a used electrophotographic photosensitive member used for forming an image in a usable state, and a reproduction reproduced by the reproducing method. It relates to an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductor used in an electrophotographic device such as a copying machine or a laser printer is treated as a consumable item. However, the life of an electrophotographic photoreceptor used for forming a copy image is mainly due to abrasion of a charge transport layer on an outermost surface layer, adhesion of toner and discharge products, and the like. By regenerating the lower functional layer and the conductive substrate, it is possible to save resources and reduce production costs.

As an example, Japanese Patent Application Laid-Open No. 2-248957 discloses a method in which a used charge transport layer of an electrophotographic photosensitive member is removed by a solvent or cutting, and a new charge transport layer is applied again. I have.

However, in the method of removing the charge transport layer, an organic solvent that dissolves the charge transport layer also dissolves or swells the underlying charge generation layer, and dissolves and removes the local charge generation material and the binder resin locally. Cause separation. Further, even if the charge transport layer alone is removed by cutting, the charge generation layer is damaged because the mechanical strength of the charge generation layer is low. Therefore, even if the charge transport layer is applied thereon again, the electrical characteristics such as the occurrence of image quality defects such as black spots and the decrease in sensitivity will be deteriorated.

Japanese Patent Application Laid-Open Nos. 8-220779 and 8-286394 disclose that an entire photosensitive layer of an electrophotographic photosensitive member is immersed in an organic solvent capable of dissolving or swelling.
A method of reusing a conductive substrate by sequentially immersing the photosensitive layer in hot water and cold water to peel off the entire photosensitive layer is disclosed.

However, in the method of stripping the entire photosensitive layer using an organic solvent, it is difficult to completely remove the photosensitive layer to such an extent that the conductive substrate can be reused. The processing method requires a large amount of solvent and processing time, and thus has problems such as safety due to the used solvent, adverse effects on waste liquid treatment and the environment, and effects on manufacturing costs.

[0007] In any of the recycling / reusing methods, it is necessary to remove the drum flange and the filler inside the drum of the electrophotographic photosensitive member from the used drum-shaped electrophotographic photosensitive member in the recycling / reusing process. However, these members are generally fixed to the electrophotographic photoreceptor with an adhesive or the like, and cannot be easily removed. It is very likely that the conductive substrate of the electrophotographic photosensitive member will be deformed and cannot be reused.

[0008]

Accordingly, the present invention provides
It is an object of the present invention to solve the above-described problems in the related art. That is, an object of the present invention is to provide a method for reproducing an electrophotographic photosensitive member that can be reused by a simple and easy method with respect to a used electrophotographic photosensitive member, and a reproduced electrophotographic photosensitive member reproduced by the reproducing method. Is to provide.

Another object of the present invention is to provide an electrophotographic photoreceptor capable of regenerating a used electrophotographic photoreceptor at low cost while saving materials, reducing waste and conserving resources. An object of the present invention is to provide a reproducing method and a reproduced electrophotographic photosensitive member reproduced by the reproducing method.

[0010]

As a result of intensive studies, the present inventor has found that an electrophotographic photoreceptor having at least a photosensitive layer on the surface of a conductive substrate reaches a limit of use and becomes unusable. The main factors are deterioration of chargeability due to abrasion of the photosensitive layer or local uneven wear, chemical degradation due to adhesion of discharge products near the surface of the photoconductor, and adhesion of toner and its additives to the surface of the photoconductor. It was found that the sensitivity was lowered due to (contamination) or the like, and the image quality was defective.

Therefore, the above object can be achieved by removing a worn (and unevenly worn) portion, a deteriorated and contaminated portion of the photosensitive layer, forming a new photosensitive layer and regenerating the electrophotographic photosensitive member. As a result, the present invention has been completed.
That is, the present invention provides a method in which a used electrophotographic photosensitive member having at least a photosensitive layer on the surface of a conductive substrate is subjected to precision polishing so that a variation in film thickness after polishing is within a range of ± 1 μm or less. The photosensitive layer is removed while leaving the film thickness of
A method for reproducing an electrophotographic photosensitive member, characterized in that a new surface layer is formed.

According to the present invention, a used electrophotographic photosensitive member (in the present invention, a "used electrophotographic photosensitive member"
It refers to an electrophotographic photoreceptor in which the electrical characteristics and image characteristics have deteriorated due to abrasion (including uneven abrasion), deterioration, or contamination of a photosensitive layer such as a charge transport layer due to long-term use. ), A reusable electrophotographic photoreceptor can be reproduced by a simple and easy method.

In the present invention, the removal of the photosensitive layer by precision polishing does not remove the entire charge transport layer or the entire photosensitive layer by cutting or a solvent as in the prior art.
The photosensitive layer is polished leaving a constant film thickness. That is, the photosensitive layer is peeled off to leave the charge generation layer and the charge transport layer (part of it), without damaging the charge generation layer, and also causing a problem due to a failure to completely remove the photosensitive layer. I can't get it. Further, by leaving a usable charge generation layer, resource saving can be achieved. The photosensitive layer to be removed by precision polishing may be either the surface protective layer alone or both the surface protective layer and the charge transport layer for an electrophotographic photosensitive member having a surface protective layer from the beginning.

A new surface layer is formed on the polished surface. The new surface layer may be a charge transport layer or a charge transport layer and a surface protective layer. By providing a surface protective layer as the outermost surface layer, it becomes higher in mechanical strength than the original electrophotographic photosensitive member.

According to the method for reproducing an electrophotographic photoreceptor of the present invention as described above, a used electrophotographic photoreceptor is regenerated in a state similar to or higher than the initial state. The term "photoconductor" refers to an electrophotographic photoconductor obtained by regenerating a used electrophotographic photoconductor in a usable state by a series of operations.) At this time, in the method of reproducing the electrophotographic photoreceptor of the present invention, the photosensitive layer is removed by precision polishing while leaving a constant film thickness so that the film thickness variation after polishing is within a range of ± 1 μm or less. In addition, the reference line average roughness (Ra) of the surface after precision polishing can be set to 0.1 μm or less, and the surface of the regenerated electrophotographic photosensitive member also becomes extremely smooth as compared with the conventional cutting and the like. The characteristics of the electrophotographic photosensitive member are good. In particular, the reference line average roughness (Ra) of the photosensitive layer surface
Can be easily adjusted to 0.01 μm or less, and in such a surface state, there is no inferiority to a new state.
A reproduced electrophotographic photosensitive member having extremely good characteristics can be obtained.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the method for reproducing an electrophotographic photoreceptor of the present invention, the used electrophotographic photoreceptor having at least a photosensitive layer on the surface of a conductive substrate is subjected to precision polishing to change the film thickness after polishing by ± 1 μm.
m, the photosensitive layer is removed while leaving a constant film thickness so as to be within a range of m or less, and then a new surface layer is formed.

The photosensitive layer to be removed is formed by sequentially laminating at least a charge generation layer and a charge transport layer, and further forming a surface protective layer as necessary. Of course, an electrophotographic photoreceptor having a surface protective layer formed thereon has a high mechanical strength of the photosensitive layer, but the abrasion, deterioration, and contamination of the surface protective layer progress over a long period of time. Therefore, in the electrophotographic photosensitive member to be reproduced according to the present invention,
When the surface protective layer is formed, removal of the photosensitive layer by precision polishing is performed including the surface protective layer. Further, an undercoat layer may be formed below the photosensitive layer.

In the present invention, the used electrophotographic photoreceptor is subjected to precision polishing to remove the photosensitive layer while leaving a constant film thickness such that the film thickness after polishing is within a range of ± 1 μm or less. As described above, by making the thickness of the photosensitive layer after polishing uniform, the surface of the finally obtained reproduced electrophotographic photosensitive member can be smoothed, and a reproduced electrophotographic photosensitive member having high characteristics can be obtained.

Here, "fluctuation in film thickness after polishing" refers to the difference in the film thickness of the entire photosensitive layer formed on the surface of the conductive substrate after polishing by precision polishing depending on the portion on the entire surface of the electrophotographic photosensitive member. More specifically, it refers to the distance from the center value of the film thickness. For example, if the remaining thickness of the photosensitive layer is 1
When precision polishing is performed at 0 μm, the center value of the film thickness is approximately 10 μm. In this case, the film thickness after polishing is adjusted to be in the range of 9 μm to 11 μm.

In the present invention, the "film thickness variation after polishing" is measured by measuring the thickness of the photosensitive layer on the entire surface of the electrophotographic photosensitive member after polishing at 30 points, and taking the average thereof as a central value. It was measured by determining the distance between the maximum and minimum values.

If the variation in the film thickness after the polishing exceeds the range of ± 1 μm or less, the surface smoothness of the photosensitive layer remaining after the polishing is not sufficient, which may affect the characteristics of the electrophotographic photosensitive member. . The variation in film thickness after polishing is ± 0.5
It is preferable that the thickness be not more than μm. The film thickness of the photosensitive layer after polishing can be measured by a conventionally known measuring device or measuring method such as a film thickness meter using eddy current or a film thickness meter using interference light.

In the present invention, any means may be used as precision polishing, that is, a polishing means for removing the photosensitive layer as long as it has an accuracy satisfying the range of the film thickness variation after the above polishing. Specific examples of the polishing apparatus capable of precision polishing include a brush polishing machine having a brush made of nylon, rayon, Teflon, polyester or the like; a buff polishing machine having a buff member made of felt, rubber, resinoid, polyvinyl alcohol, or the like. A sand blast device for spraying an abrasive with pressure; a liquid honing device. As the polishing agent used in combination with these polishing apparatuses, powders of aluminum oxide, silicon oxide, silicon carbide, silicon boride, chromium oxide, iron oxide, etc. are used, and the particle size of the polishing agent is 20 to 500 μm. Used.

In the case of a drum-shaped electrophotographic photosensitive member, in order to uniformly polish the photosensitive layer in any of the polishing apparatuses, it is effective to rotate the used electrophotographic photosensitive member. The gear provided on the flange of the electrophotographic photoreceptor for driving in the printer is provided on a polishing apparatus using a rotating mechanism that can be used for rotating the electrophotographic photoreceptor during polishing as it is, so that it can be polished. The electrophotographic photosensitive member can be rotated.

The conditions for precision polishing should be appropriately adjusted according to the equipment used, the type of photosensitive layer of the electrophotographic photosensitive member, the state of the used photosensitive layer, the material and shape of the conductive substrate, and the like. The following shows an example of polishing conditions when a buffing machine is used. When using a buffing machine for precision polishing,
The particle size of the abrasive is appropriately set according to the desired film thickness variation and surface roughness. The abrasive has a concentration of 1%.
It is prepared by a known method as a dispersion of 0 to 500 g / l. The load on the buff, which is another polishing condition,
The number of rotations (buff member, photoreceptor to be polished), the moving speed of the buff, and the number of rotations are appropriately set according to the desired film thickness variation and surface roughness. However, such conditions are not absolute, and optimal conditions may be appropriately selected in consideration of other conditions.

The electrophotographic photosensitive member that has been subjected to precision polishing uses purified water (purified water) such as ion-exchanged water or distilled water, and removes abrasive powder, deposits, and the like by ultrasonic cleaning, brush cleaning, and rinsing. It is desirable to remove it. The purified water used in these washing processes can be reused after processes such as filtration, ion exchange, and distillation. And, for example, 50 ° C. to 12
After drying at a temperature of about 0 ° C., a new surface layer, described below, is formed.

The reference line average roughness (Ra) of the photosensitive layer surface of the electrophotographic photosensitive member after the formation of a new surface layer is as follows:
It is preferably 0.01 μm or less. According to the reproducing method of the present invention, the surface of the photosensitive layer tends to be extremely smooth compared with the conventional reproducing method using cutting or the like, and the reference line average roughness (Ra) of the polished photosensitive member surface is 0.1 μm. By setting the average particle diameter to the following range, the surface of the photoreceptor after reproduction can easily have the reference line average roughness (Ra) within the above range, and if the surface state of Ra is 0.01 μm or less, good characteristics can be reproduced. It can be an electrophotographic photosensitive member.

By setting the average roughness (Ra) of the reference line on the surface of the photoreceptor after polishing to 0.1 μm or less, the surface roughness of the regenerated electrophotographic photoreceptor is brought to the same surface condition as a new one. Can be. The reference line average roughness (R
Even when a) is larger than 0.1 μm, the electrophotographic photoreceptor after reproducing it (providing a new surface layer) can be used in the initial stage of use, but has an effect on image quality. In some cases, the time required for the surface roughness to be reduced becomes shorter, which may lead to a shorter life.

When the used electrophotographic photosensitive member to be reproduced in the present invention is in the form of a drum, the contact portion between the electrophotographic photosensitive member, the drum flange, and the filling material inside the drum of the electrophotographic photosensitive member is reduced. It may have a structure that can be easily detached or a structure that cannot be detached by an adhesive or fitting.

In the former case, for example, the contact portions between the electrophotographic photosensitive member and the drum flange and the filling material inside the drum are fixed when driven in a copying machine and a printer, and easily used when the used electrophotographic photosensitive member is reproduced. To be detachable, fix the end of the electrophotographic photosensitive member, the drum flange and the filler by screwing, and fix the end of the electrophotographic photosensitive member, the drum flange and the filler through a pin For example, a rectangular notch is provided at the end of the electrophotographic photosensitive member, while a rectangular convex portion is provided on the drum flange and the filler, and both are fitted and fixed.

In these cases, the drum flange and filler are removed from the electrophotographic photoreceptor after precision polishing and, if necessary, cleaning, before applying a new surface layer again. As a means for forming a new surface layer, any conventionally known method such as blade coating, spray coating, dip coating and the like can be adopted.

In the latter case, since the contact portion between the electrophotographic photosensitive member and the drum flange and the filling material inside the drum cannot be separated, a method is adopted in which the electrophotographic photosensitive member can be coated while the drum flange and the filling material inside the drum remain. There is a need to. With such a method, any means may be used as a means for forming a new surface layer,
Specific examples include the flow coating shown below.

By rotating the electrophotographic photosensitive member about the axis of the electrophotographic photosensitive member and moving the liquid discharge nozzle relatively in the direction of the axis, the coating liquid is discharged from the liquid discharge nozzle. A coating method in which a coating solution is spirally applied to the electrophotographic photosensitive member to form a continuous coating film.

The electrophotographic photosensitive member is rotated around the axis of the electrophotographic photosensitive member, and the coating liquid discharged from the liquid discharge nozzle is received by a blade, a roll, a pad, or the like, and pressed against the electrophotographic photosensitive member. And applying the application liquid spirally while relatively moving in the axial direction together with the nozzle to form a continuous application film.

In any of the methods, it is effective to rotate the electrophotographic photosensitive member for uniform application, and it is possible to rotate the electrophotographic photosensitive member by using the same method as in the polishing. it can. As the newly formed surface layer, a charge transport layer and / or a surface protective layer, or both, are formed according to the purpose of use.

The newly formed charge transport layer may be a charge transport layer made of the same material as the existing charge transport layer, or a charge transport layer made of a different material, and is formed by a known material. . As the surface protective layer, a surface protective layer in which conductive particles such as a metal oxide are dispersed in a thermoplastic or thermosetting binder resin, and a surface in which a charge transport material is molecularly dispersed in a thermosetting binder resin. Any of a protective layer, a surface protective layer in which a reactive functional group is introduced into the charge transporting material to form a crosslinked structure with a thermosetting binder resin, and the like may be formed. Is done. Further, a thermal cross-linkable surface layer having a charge transporting property described later may be used as the surface protective layer.

Hereinafter, the electrophotographic photosensitive member reproduced in the present invention will be described in detail. In the electrophotographic photosensitive member reproduced in the present invention, as the conductive substrate, aluminum,
Drums made of metals such as nickel, chromium, and stainless steel; aluminum, titanium, nickel, chromium,
A plastic drum provided with a thin film of stainless steel, gold, vanadium, tin oxide, indium oxide, ITO or the like is used, but is not limited thereto. Further, if necessary, the surface of the conductive substrate can be subjected to various treatments within a range that does not affect the image quality. For example, anodic oxide film treatment, thermal hydroxylation treatment or chemical treatment of the surface, coloring treatment, or irregular reflection treatment such as graining can be performed.

As the undercoat layer formed as required in the present invention, a layer formed by a known technique can be used. The undercoat layer is composed of a binder resin and other materials such as fine particles added as needed. As the binder resin used for the undercoat layer, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polyurethane resin, melamine resin, benzoguanamine resin,
Polyimide resin, polyethylene resin, polypropylene resin, polycarbonate resin, acrylic resin, methacrylic resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, water-soluble polyester resin, nitrocellulose, casein, gelatin And known materials such as polyglutamic acid, starch, starch thiacetate, amino starch, polyacrylic acid, polyacrylamide, zirconium chelate compound, titanyl chelate compound, titanyl alkoxide compound, organic titanyl compound, and silane coupling agent. These materials can be used alone or in combination of two or more.

Further, the undercoat layer can be mixed with fine particles of titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, barium titanate, silicone resin and the like. The undercoat layer was prepared by dissolving and dispersing a binder resin and other materials such as fine particles added as necessary in an appropriate solvent to prepare a coating liquid, and applying the coating liquid to the conductive substrate surface. Thereafter, it can be formed by heating and drying.

As a coating method for forming the undercoat layer, known methods such as blade coating, spray coating, and dip coating are employed. The thickness of the undercoat layer is preferably about 0.01 to 10 μm, and more preferably about 0.05 to 2 μm.

In the electrophotographic photosensitive member reproduced according to the present invention, as the charge generation layer, those formed by a known technique can be used. These charge generation layers are formed by including a charge generation material in a binder resin. As the charge generating material, amorphous selenium, crystalline selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and selenium alloys, zinc oxide, inorganic photoconductive materials such as titanium oxide, phthalocyanine, squarylium, Organic pigments and dyes such as an anthrone-based, perylene-based, azo-based, anthraquinone-based, pyrene-based, pyrylium salt, and thiapyrylium salt are used. Of these, phthalocyanine compounds are desirable in terms of photosensitivity and stability, and particularly preferred are metal-free phthalocyanines, oxytitanium phthalocyanines, gallium phthalocyanines, hydroxygallium phthalocyanines, and tin phthalocyanines.

Examples of the binder resin for the charge generation layer include polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal resin, polycarbonate resin,
Polyester resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, silicone resin, phenol resin, poly-N-vinyl carbazole resin, etc., but are not limited thereto. It is not something to be done. These binder resins can be used alone or in combination of two or more.

The charge generation layer was prepared by dissolving and dispersing a charge generation material and a binder resin in an appropriate solvent to prepare a coating solution, and forming the coating solution on the surface of the conductive substrate or on the surface of the conductive substrate. After being applied on the undercoat layer, it can be formed by heating and drying. Solvents used when preparing a coating solution for forming a charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, and n-acetic acid. -Ordinary organic solvents such as -butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform and the like can be used alone or in combination of two or more.

As a method for applying the coating solution for forming the charge generation layer, the same known methods as those described for the undercoat layer can be applied. The compounding ratio (weight ratio) of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10,
The thickness of the charge generation layer is generally 0.1 to 5 μm, preferably 0.2 to 2.0 μm.

In the electrophotographic photosensitive member reproduced according to the present invention, the charge transport layer formed from the beginning and the charge transport layer as a new surface layer newly formed by reproduction are formed by known techniques. Can be used. These charge transport layers are formed containing a charge transport material and a binder resin, or are formed containing a polymer charge transport material.

Examples of the charge transport material include quinone compounds such as p-benzoquinone, chloranil, bromanyl, and anthraquinone; tetracyanoquinodimethane compounds;
A fluorenone compound such as 4,7-trinitrofluorenone; a xanthone compound; a benzophenone compound; a cyanovinyl compound; an ethylene compound; an electron transporting compound such as a triarylamine compound, a benzidine compound, an arylalkane compound; Hole-transporting compounds such as aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials can be used alone or in combination of two or more. In particular, a triphenylamine-based compound and a benzidine-based compound can be particularly preferably used because they have high charge (hole) transporting ability and excellent stability. These can be used alone or
A mixture of more than one species can be used.

Examples of the binder resin include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, and vinylidene chloride-acrylonitrile copolymer. Polymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-
Known resins such as formaldehyde resin, styrene-acrylic resin, styrene-alkyd resin, poly-N-vinylcarbazole and polysilane can be used. Among these, it is preferable to contain at least one selected from the group consisting of a polycarbonate resin, a polyarylate resin, and a polyester resin.

As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane can be used. In particular, JP-A-8-
The polyester-based polymer charge transporting materials disclosed in 176293 and JP-A-8-208820 have high charge transporting properties and are particularly preferable. The polymer charge transport material alone can form a film, but may be mixed with the binder resin to form a film.

The charge transporting layer is prepared by dissolving and dispersing a charge transporting material and a binder resin or a polymer charge transporting material and, if necessary, a binder resin in an appropriate solvent to prepare a coating solution. The liquid can be formed by applying the liquid on the charge generation layer formed on the surface of the conductive substrate and then drying by heating.

Solvents used for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; ketones such as acetone and 2-butanone; halogens such as methylene chloride, chloroform and ethylene chloride. Ordinary organic solvents such as fluorinated aliphatic hydrocarbons; cyclic or linear ethers such as tetrahydrofuran, ethyl ether and dioxane; can be used alone or in combination of two or more.

As the method of applying the coating solution when forming the charge transport layer, the same known methods as those described for the undercoat layer and the charge generation layer can be used. In particular, when applying the used electrophotographic photoreceptor to regenerate it, the means described for the formation of the new surface layer is employed. The preferred thickness of the charge transport layer is from 15 to 50 μm, more preferably from 20 to 40 μm.

The charge transport layer formed as a new surface layer is preferably a thermal cross-linkable surface layer having a charge transport property, in order to achieve excellent mechanical strength. In addition, the thermal crosslinking type surface layer having charge transportability may be formed as a surface protective layer after forming the above-described charge transport layer. Thermal crosslinkable surface layer having charge transportability (hereinafter, referred to as
It may be simply referred to as “thermally crosslinked surface layer”. The examples of the heat-crosslinkable surface layer A and the heat-crosslinkable surface layer B include the following.

(Thermal Crosslinkable Surface Layer A) Thermally Crosslinkable Surface Layer A
Is formed by three-dimensionally cross-linking and polymerizing at least one kind of the charge transporting substances represented by the following structural formulas (1) to (3) and an isocyanate compound having three or more functional groups.

Structural formula (1)

Embedded image

(Wherein R ₁ , R ₂ and R ₃ are a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms) Represents an amino group substituted with a group, and T is a group having 1 to 10 carbon atoms.
Represents a divalent hydrocarbon group which may be branched, and n represents 0 or 1. )

Structural formula (2)

Embedded image

Wherein Y is a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a phenyl group, or a halogen atom, An alkyl group having 1 to 5 alkyl groups or an alkyl group substituted with a halogen atom, and 1 carbon atom
Represents a phenyl group having any one of the alkoxy groups in the range of from 5 to 5, and T is a branched phenyl group having 1 to 10 carbon atoms.
Represents a monovalent hydrocarbon group, and n represents 0 or 1. )

Structural formula (3)

Embedded image

(Wherein R ₄ and R ₅ represent hydrogen or an alkyl group having 1 to 5 carbon atoms; X represents hydrogen and 1 carbon atom;
Represents an alkyl group or a phenyl group ranging from 5 to 5,
T represents a divalent hydrocarbon group having 1 to 10 carbon atoms in the aliphatic portion which may be branched; n represents 0 or 1;
₁ , Ar ₂ and Ar ₃ represent a phenyl group, a naphthyl group or an anthracene group, and include a plurality of halogen atoms,
It may be substituted with a plurality of alkyl groups ranging from 1 to 5 and a plurality of alkoxy groups ranging from 1 to 5 carbon atoms. )

Specific examples of Ar ₁ in the structural formula (3) are shown in Tables 1 and 2 below, and specific examples of Ar ₂ and Ar ₃ are shown in Tables 3 and 4 below.

Table 1

[Table 1]

Table 2

[Table 2]

Table 3

[Table 3]

Table 4

[Table 4]

Next, specific examples of the divalent hydrocarbon group represented by T in the structural formulas (1) to (3) are shown in Table 5 below.

Table 5

[Table 5]

As a component of the heat-crosslinkable surface layer A, a compound further added with a glycol compound or a bisphenol compound, if necessary, may be used. These compounds having a hydroxy group form a crosslinked structure by replacing a part of the compounds of the structural formulas (1) to (3).

These glycol compounds having a hydroxy group can be freely selected from those having two or more hydroxy groups in the molecule and capable of polymerizing with isocyanate. Examples thereof include ethylene glycol, propylene glycol, and butanediol. And polyethylene glycol.

Examples of other glycol compounds having a hydroxy group include various polymers and oligomers having a reactive hydroxy group such as acrylic polyols and oligomers thereof, and polyester polyols and oligomers thereof.

In order to form a three-dimensional network structure by crosslinking, it is necessary to use an isocyanate compound having three or more functional groups, that is, a compound having three or more reactive isocyanate groups. Thereby, the thermal crosslinking type surface layer A can have a high-density crosslinking structure.

As the isocyanate compound having three or more isocyanate groups, it is more preferable to use a derivative obtained from an isocyanate monomer or a modified polyisocyanate such as a prepolymer. Examples thereof include an adduct modified product obtained by adding an isocyanate to a polyol having 3 or more functional groups, a buret modified product obtained by modifying a compound having a urea bond with an isocyanate compound, an allophanate modified product obtained by adding an isocyanate to a urethane group, and an isocyanurate modified product Body, etc. are particularly preferred,
In addition, modified carbodiimides are used.

In particular, the buret-modified or isocyanurate-modified hexamethylene diisocyanate represented by the following structural formula (4) or (5) can be used as the heat-crosslinkable surface layer A. Particularly excellent in mechanical strength and electrical properties.

[0072]

Embedded image

The isocyanate compound which can be used together with the above isocyanate is tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, tolidine diisocyanate, 1,6-hexamethylene diisocyanate, xylene diisocyanate, lysine isocyanate. , Tetramethyl xylene diisocyanate, 1,
3,6-hexamethylene triisocyanate, lysine ester triisocyanate, 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-
Isocyanate methyl octane, triphenylmethane triisocyanate, tris (isocyanate phenyl)
General isocyanate monomers such as thiophosphate.

A blocked isocyanate which is included in the modified polyisocyanate and reacted with a blocking agent for temporarily masking the activity of the isocyanate group can also be preferably used. This is preferable from the viewpoint of extending the pot life of the coating solution for forming the thermal crosslinking type surface layer A.

In order to form a crosslinked cured film in the thermally crosslinked type surface layer A, at least one kind of the charge transporting material having a hydroxy group represented by the above structural formulas (1) to (3) is contained. Compound, a compound having another hydroxy group as needed, various additives described below, and a mixture containing a solvent and the like were mixed to prepare a coating solution for forming the thermal cross-linkable surface layer A, and this was used. After coating on the charge transport layer remaining after the precision polishing of the electrophotographic photoreceptor, a film is formed by cross-linking polymerization to obtain a thermo-crosslinkable surface layer A.

The mixing ratio of the charge transporting substance having a hydroxy group represented by the above structural formulas (1) to (3) and the isocyanate compound in the coating solution for forming the thermal crosslinking type surface layer A is as follows: The number of hydroxy groups to be reacted): (the number of reacting isocyanate groups) is preferably in the range of 1.5: 1 to 1: 1.5, and 1.2: 1 to 1.2: 1.
More preferably, it is set to 1: 1.2. Excessive hydroxyl groups remaining beyond this mixing ratio may increase the hydrophilicity of the surface of the thermo-crosslinkable surface layer A, causing a problem that the image characteristics under high temperature and high humidity may deteriorate. ,
Care must be taken including reaction conditions. Care must be taken because the isocyanate compound is deactivated by moisture in the air and the like, and the number of reacting isocyanates may decrease. In that case, it is effective to prepare the isocyanate group so that it is slightly excessive.

The content of the charge transport material portion (the structural portion having charge transport ability in the layer) in the thermally crosslinked type surface layer A is determined by the molecular weight of the hydroxy group-containing compound and the molecular weight of the isocyanate compound. In order to maintain the electrical properties of the electrophotographic photoreceptor and also have mechanical strength, the content of the charge transporting substance portion in the entire thermally crosslinked surface layer A needs to be 5% by weight or more and 90% by weight or less. Therefore, it is desirable that the content be 25% by weight or more and 75% by weight or less. In the thermal cross-linking type surface layer A, the charge transport material portion is incorporated in the network structure by bonding, so that the charge transport material (portion) is larger than the charge transport layer in which the ordinary low molecular weight charge transport material is dispersed. It is possible to introduce

The thermal cross-linkable surface layer A may be added with various binder resins in order to improve its film formability and flexibility. As such a binder resin, those having compatibility with the film after cross-linking polymerization can be used, for example,
Various polymers such as polycarbonate, polyester, acrylic, polyvinyl alcohol, and polyamide can be used. However, in order to maintain the mechanical strength and the photoelectric characteristics, it is desirable that the content of these binder resins in the thermo-crosslinkable surface layer A be 60% by weight or less.

In order to carry out the cross-linking polymerization of the thermal cross-linkable surface layer A, it is sufficient to coat the used electrophotographic photosensitive member on the charge transport layer remaining after the precision polishing, and then heat it. The addition reaction between the hydroxy group and the isocyanate group depends on the reactivity between the compounds used, but generally does not require a catalyst or the like, and only requires heating. When a solvent is used at the time of the coating, a heat treatment can be performed simultaneously with or subsequent to the drying step.

When it is desired to accelerate the cross-linking reaction, catalysts such as organic metal compounds such as dibutyltin dilaurate, inorganic metal compounds, monoamines, diamines, triamines, cyclic amines, alcohol amines, ether amines, etc. May be added according to a conventional method. It is also possible to add other known additives used for forming a coating film to the heat-crosslinkable surface layer A, for example, an antioxidant, a leveling agent, an ultraviolet absorber, a light stabilizer, and a surfactant. Known agents such as agents can be used.

(Thermal Crosslinkable Surface Layer B) Thermally Crosslinkable Surface Layer B
Is a crosslinked cured film formed containing the compound represented by the following general formula (I).

Formula (I) F- [DA] _b (wherein F is an organic group derived from a photofunctional compound,
Is a flexible subunit, and A is —Si (R ¹ ) _(3-a) (O
R ² ) _a substituted silicon group having a hydrolyzable group represented by a,
b represents an integer of 1 to 4. Here, R ¹ is hydrogen, an alkyl group, a substituted or unsubstituted aryl group, R ² is hydrogen,
Represents an alkyl group or a trialkylsilyl group;
Represents an integer. )

The organic group derived from the photofunctional compound represented by F in the general formula (I) is a unit having a photoelectric property, specifically, a photocarrier transport property. Known structures can be used as they are. As F, specifically, it has a hole transporting property such as a triarylamine-based compound, a benzidine-based compound, an arylalkane-based compound, an aryl-substituted ethylene-based compound, a stilbene-based compound, an anthracene-based compound, and a hydrazone-based compound. A compound skeleton and a compound skeleton having an electron transporting property such as a quinone compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, an ethylene compound, or the like can be used.

The flexible subunit represented by D in the general formula (I) is directly bonded to an organic group represented by F for imparting photoelectric properties to a three-dimensional inorganic glassy network. And a substituted silicon group represented by A. Further, it also has a function of imparting appropriate flexibility to an inorganic vitreous network having fragility on the other hand, and improving toughness as a film.
As a specific structure of D, -C _x H _2x- (x is 1 to 1
5 _{integer), - C x 'H (} 2x'-2) - (x' is an integer of _{2~15), - C x "H} (2x" -4) - (x " is an integer of 2 to 15) A divalent hydrocarbon group, a divalent aryl group, -CO
O -, - S -, - O -, - CH 2 -C 6 H 4 -, - N = C
Examples thereof include H-,-(C ₆ H ₄ )-(C ₆ H ₄ )-, a combination thereof, and those further having a substituent introduced.

Among the compounds represented by the general formula (I), the compounds represented by the following general formula (II) are particularly desirable in terms of excellent photoelectric properties, mechanical properties and oxidation resistance.

[0086]

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[0087] (wherein, Ar ¹ to Ar ⁴ each independently represent a substituted or unsubstituted aryl group, Ar ⁵ represents a substituted or unsubstituted aryl group or arylene group, and among Ar ¹ to Ar ⁵ 1-4 are -Y-Si
_{^{(R 5) (3-c}} ) having a substituent represented by (OR ⁶⁾ _c, R ⁵
Represents a hydrogen, an alkyl group, a substituted or unsubstituted aryl group, R ⁶ represents a hydrogen, an alkyl group, or a trialkylsilyl group, c represents an integer of 1 to 3, and k represents 0 or 1. The Y is, -C _x H _2x - _(x is 1 to 15 _{integer), - C x 'H (} 2x'-2) - (x' is from 2 to 15 integer), -
A hydrocarbon group represented by Cx _" H _{(2x" -4)} -(x "is an integer of 2 to 15), a substituted or unsubstituted divalent aryl group,
CH = represents a divalent group having at least one or more selected from the group consisting of -O- and -COO-. )

In the above general formula (II), Ar ^{1 to} Ar ⁴
Each independently represents a substituted or unsubstituted aryl group, and specific examples include the structures shown below.

[0089]

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Here, X is —Y—Si (R ⁵ )
_(3-c) (OR ⁶ ) represents a substituent represented by _c , wherein R ³ is hydrogen, an alkyl group having 1 to 4 carbon atoms, an unsubstituted alkyl group having 1 to 4 carbon atoms or 1 carbon atom. Phenyl group substituted by an alkoxy group having 4 to 4 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms. R ⁴ is selected from hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and halogen. m and s represent 0 or 1, and t is 1
To 3 and Ar is selected from the following.

[0091]

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Here, R ₈ is selected from hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and halogen. T represents an integer of 0 to 3.

Further, Z ′ is selected from the following structures.

[0094]

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In the above general formula (II), Y is
No. shown below. Structures 1 to 11 are exemplified.

[0096]

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Here, R ⁴ is selected from hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and halogen. x is an integer of 1 to 10, x 'and x "are each an integer of 2 to 15, y and z are each an integer of 1 to 5, and t is an integer of 1 to 3. Among the above structures, No. .1 to 7 are preferred.

On the other hand, Ar in the general formula (II)
⁵ represents a substituted or unsubstituted aryl group or an arylene group, and specific examples include the following structures.

When k in the general formula (II) is 0, specific examples of Ar ⁵ include:

[0100]

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When k in the general formula (II) is 1, specific examples of Ar ⁵ include:

[0102]

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Each of them can be mentioned. here,
R ³ is hydrogen, an alkyl group having 1 to 4 carbon atoms, unsubstituted
Or an alkyl group having 1 to 4 carbon atoms or 1 to 4 carbon atoms
A phenyl group substituted with an alkoxy group, having 7 to 1 carbon atoms
It is selected from 0 aralkyl groups. R ⁴ is hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms,
Selected from halogen. s represents 0 or 1, and t represents an integer of 1 to 3. Ar is selected from the structures shown below.

[0104]

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Here, R ⁴ is selected from hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and halogen. T represents an integer of 1 to 3. Further, Z is selected from the structures shown below.

[0106]

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Here, R ⁵ is selected from hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and halogen. Further, q and r each represent an integer of 1 to 10, t 'represents an integer of 1 or 2, and W is selected from the following groups.

[0108]

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Here, s' represents an integer of 0 to 3.

The content of the compound represented by the general formula (I) in the thermally crosslinked surface layer B is in the range of 5 to 50% by weight based on the total solid content of the thermally crosslinked surface layer B. Is 10
40% by weight.

As a compound which can form a crosslinked cured film when used simultaneously with the compound represented by the general formula (I) (particularly, the general formula (II)), a compound represented by the following general formula (III) is preferably used.

[0112]

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(Where A is —Si (R ³ ) _(3-b) (O
R ⁴ ) represents a substituent represented by _b , and B represents an n-valent hydrocarbon group which may contain a branch, an n-valent aryl group, -NH
, Or a combination thereof, and n represents an integer of 2 or more. R ³ represents a hydrogen, an alkyl group, a substituted or unsubstituted aryl group, R ⁴ represents a hydrogen, an alkyl group, or a trialkylsilyl group, and b represents an integer of 1 to 3. )

The compound represented by the general formula (III) is a compound having two or more alkoxysilyl groups (A in the structural formula) at the terminal, and is represented by the general formula (I) (particularly the general formula (I)
It reacts with the alkoxysilyl group in the compound represented by I)) to form a Si—O—Si bond to form a three-dimensional crosslinked cured film.

The compound represented by the general formula (I) (especially the general formula (II)) can form a crosslinked cured film by itself, but the compound represented by the general formula (III) Since the structure has alkoxysilyl groups at both ends, it is considered that when the compound is used at the same time, the crosslinked structure of the crosslinked cured film tends to be three-dimensional and has higher mechanical strength. Further, similar to the flexible subunit represented by D in the compound represented by formula (I),
It also has a role of imparting appropriate flexibility to the crosslinked cured film. In particular, the compound represented by the general formula (III) is preferably a compound represented by any of the following general formulas.

[0116]

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(Wherein T ₁ and T ₂ represent a divalent or trivalent hydrocarbon group which may be branched, and A represents a group represented by the general formula (I)
H) is the same as the substituent represented by A in II),
i and j are integers of 1 to 3, and are selected so that the number of A in the molecule is 2 or more. )

The above-mentioned general formula (III) in the thermally crosslinked type surface layer B
Is in the range of 20 to 80% by weight based on the total solid content of the thermally crosslinkable surface layer B, and is preferably 3% by weight.
It is in the range of 0 to 70% by weight.

The heat-crosslinkable surface layer B is formed from the compound represented by the above general formula (I) and, if necessary, the compound represented by the above general formula (III). Various other components may be added according to the purpose. When forming the thermo-crosslinkable surface layer B, the general formula (I) (particularly the general formula (I)
Other compounds capable of undergoing a crosslinking reaction with the compound represented by I)) may be further added. As such a compound, various silane coupling agents and commercially available silicon-based hard coat agents can be used.

Examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxysilane. Propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, tetramethoxysilane, methyltrimethylsilane Methoxysilane, dimethyldimethoxysilane, and the like can be used.

Commercially available hard coat agents include KP-8
5, CR-39, X-12-2208, X-40-97
40, X-41-1007, KNS-5300, X-4
0-2239 (all manufactured by Shin-Etsu Silicone Co., Ltd.) and A
Y42-440, AY42-441, AY49-208
(Above, manufactured by Toray Dow Corning Co., Ltd.).

It is also possible to add other known additives used for forming a coating film to the heat-crosslinkable surface layer B, for example, an antioxidant, a leveling agent, an ultraviolet absorber, and a light stabilizer. Known surfactants such as a surfactant and a surfactant can be used. In order to form a crosslinked cured film of the thermal crosslinking type surface layer B, a coating liquid obtained by mixing the compound represented by the general formula (I) and various additives is used in the above-mentioned electrophotographic photoreceptor. What is necessary is just to heat after apply | coating on the charge transport layer which remains after precision polishing. Thereby, the respective Si groups cause a three-dimensional cross-linking and curing reaction to form a strong cured film.

The cross-linking curing reaction may be carried out without a catalyst, but an appropriate catalyst may be used. As a catalyst,
Acid catalysts such as hydrochloric acid, sulfuric acid, formic acid, acetic acid and trifluoroacetic acid; bases such as ammonia and triethylamine; organic tin compounds such as dibutyltin diacetate, dibutyltin dioctoate and stannous octoate; tetra-n-butyl titanate; Organic titanium compounds such as tetraisopropyl titanate; iron salts, manganese salts, and cobalt salts of organic carboxylic acids;
Zinc salts, zirconium salts; and the like. The temperature at the time of the crosslinking and curing reaction is not particularly limited as long as it does not affect the underlying photosensitive layer (the charge generation layer and the remaining charge transport layer), but is preferably set in the range of room temperature to 150 ° C. .

[0124]

EXAMPLES The present invention will now be described more specifically with reference to examples, but the present invention is not limited thereto. In the examples and comparative examples, “parts” means “parts by weight”.

[Example 1] 1. Production of test electrophotographic photoreceptor (Formation of undercoat layer) Copolymer nylon resin (Amilan CM
A coating solution prepared by dissolving 10 parts of 8000, manufactured by Toray Co., Ltd. in a mixture of 60 parts of methanol and 40 parts of butanol was applied to a conductive substrate (aluminum drum, length 340 mm, outer diameter 30 m).
m) An undercoat layer having a thickness of 0.5 μm was formed by dip coating on the surface and drying by heating at 100 ° C. for 10 minutes.

(Formation of Charge Generation Layer) From 4 parts of oxytitanium atalocyanine pigment, 2 parts of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Union Carbide), 10 parts of xylene, and 24 parts of n-butyl acetate The resulting solution was dispersed in a sand mill for 10 hours, and 60 parts of tetrahydrofuran was added to prepare a coating solution for forming a charge generation layer. This coating solution is dip-coated on the undercoat layer,
By heating and drying at 0 ° C. for 10 minutes, a charge generation layer was formed. The thickness of the charge generation layer was 0.15 μm.

(Formation of Charge Transporting Layer) 50 parts by weight of a triarylamine compound represented by the following structural formula (a) and 50 parts by weight of a polycarbonate resin (Iupilon Z-300, manufactured by Mitsubishi Gas Chemical) are combined with monochlorobenzene 400 The solution was dissolved in parts by weight to prepare a coating solution for forming a charge transport layer. Such a coating solution is dip-coated on the charge generation layer,
By heating and drying at 5 ° C. for 1 hour, a charge transport layer having a thickness of 25 μm was formed.

[0128]

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As described above, the test electrophotographic photosensitive member was manufactured.

[0130] 2. Running test The test electrophotographic photoreceptor thus obtained was mounted on an LP4161II printer manufactured by Fuji Xerox Co., Ltd. (the drum flange and the internal filler were removable), and the test chart was used for A4 paper. A print running test was performed up to 100,000 sheets in an environment of 20 ° C. and 40% for lateral feeding (using L paper manufactured by Fuji Xerox Co., Ltd.). The average thickness of the photosensitive layer after the running test was 15 μm, and the average surface roughness (Ra) of the reference line was 0.15 μm.

[0131] 3. Production of Reproduced Electrophotographic Photoreceptor (Precision Polishing) The electrophotographic photoreceptor after the running test is subjected to a buffing machine (felt as a buffing member, particle size 20 μm as a polishing powder).
m using aluminum oxide), the photosensitive layer was precisely polished so that the film thickness of the polished photosensitive layer was 14 μm, the film thickness variation was ± 0.5 μm, and the reference line average surface roughness (Ra) was 0.08 μm. After polishing, the surface of the charge transport layer remaining on the surface of the photosensitive layer of the electrophotographic photosensitive member (hereinafter, sometimes referred to as “residual charge transport layer”) is brush-cleaned with distilled water, and
Dry at 10 ° C. for 10 minutes.

(Formation of New Surface Layer) For the electrophotographic photosensitive member that has been subjected to precision polishing and subsequent cleaning, the drum flange and the internal filler are removed, and the electrophotographic photosensitive member is subjected to the procedure described in “1. Using the same coating liquid for forming the charge transport layer as described above, the remaining charge transport layer is coated by dip coating, and then heated and dried at 115 ° C. for 1 hour, so that the photosensitive layer containing the remaining charge transport layer is again exposed. A charge transport layer (new surface layer) was formed so that the film thickness of the entire layer was 25 μm. As described above, the reproduced electrophotographic photosensitive member of Example 1 was manufactured.

4. Running Test of Reproduced Electrophotographic Photoreceptor Using the obtained regenerated electrophotographic photoreceptor, a print running test was performed in the same manner as in “2. Running Test”. In the print running test, the state of the image was appropriately visually checked halfway. The print running test was continued up to a minimum of 20,000 sheets, and further, when there was no problem in the image state, until a problem occurred. The results are summarized in Table 6 below.

Example 2 The procedure of Example 1 was repeated, except that the section of (3. Production of Reproduced Electrophotographic Photoreceptor) (Formation of New Surface Layer) was changed to the following steps. Thus, a reproduced electrophotographic photosensitive member of Example 2 was manufactured. Further, a running test of the reproduced electrophotographic photosensitive member was performed in the same manner as in Example 1. The results are summarized in Table 6 below.

(Formation of New Surface Layer) The following structural formula (c)
Is dissolved in 50 parts of cyclohexanone, and 3 parts of a solution of the burette-modified polyisocyanate represented by the above structural formula (4) (solid content: 67% by weight) is dissolved in 50 parts of cyclohexanone. Was prepared. With respect to the electrophotographic photoreceptor that has been subjected to precision polishing and subsequent cleaning, the coating solution for forming a new surface layer is coated on the remaining charge transport layer by flow coating while the drum flange and the internal filler are kept as they are. 150 minutes after drying at room temperature for 10 minutes.
Heating was performed at 60 ° C. for 60 minutes to form a charge transport layer (new surface layer) having a thickness of 9 μm (excluding the photosensitive layer including the residual charge transport layer of 14 μm).

[0136]

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Here, the mixing ratio of the compound represented by the structural formula (c) and the burette-modified polyisocyanate represented by the structural formula (4) is represented by the following formula: Total number of moles of OH groups in the compound to be obtained]:
[Total number of moles of isocyanate groups in the buret-modified polyisocyanate represented by the structural formula (4)]
It is approximately 45:55.

[Example 3] In Example 1, the procedure of Example 3 was repeated except that the section of (3. Production of regenerated electrophotographic photosensitive member) (formation of new surface layer) was changed to the following steps. Thus, a reproduced electrophotographic photosensitive member of Example 3 was manufactured. Further, a running test of the reproduced electrophotographic photosensitive member was performed in the same manner as in Example 1. The results are summarized in Table 6 below.

(Formation of New Surface Layer) The following structural formula (d)
18 parts of a compound represented by the formula, 18 parts of a curable siloxane resin (X-40-2239, manufactured by Shin-Etsu Silicone Co., Ltd.), and acetic acid 7
And a solution of 0.001 part of 1N hydrochloric acid were mixed and dissolved to prepare a new coating solution for forming a surface layer. With respect to the electrophotographic photoreceptor that has been subjected to precision polishing and subsequent cleaning, the coating solution for forming a new surface layer is coated on the remaining charge transport layer by flow coating while the drum flange and the internal filler are kept as they are. After 30 minutes of touch drying, heat treatment is performed at 120 ° C. for 2 hours to form a charge transport layer (new surface layer) having a film thickness of 10 μm (excluding the photosensitive layer including the residual charge transport layer of 14 μm). did.

[0140]

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Comparative Example 1 In the same manner as in Example 1, except that the section of (Precision Polishing) in “3. Production of Reproduced Electrophotographic Photoreceptor” was changed to the following (Washing) step. Thus, a reproduced electrophotographic photosensitive member of Comparative Example 1 was manufactured. Further, a running test of the reproduced electrophotographic photosensitive member was performed in the same manner as in Example 1. The results are summarized in Table 6 below.

(Washing) The electrophotographic photosensitive member after the running test was
It was brush-washed with distilled water and dried at 100 ° C. for 10 minutes.

[Comparative Example 2] In Example 1, except that the section of (Precision Polishing) in “3. Production of Reproduced Electrophotographic Photoreceptor” was changed to the following step (Dissolution and Removal of Charge Transport Layer).
In the same manner as in Example 1, a reproduced electrophotographic photosensitive member of Comparative Example 2 was manufactured. Further, a running test of the reproduced electrophotographic photosensitive member was performed in the same manner as in Example 1. The results are summarized in Table 6 below.

(Dissolution and Removal of Charge Transport Layer) The electrophotographic photosensitive member after the running test was subjected to ultrasonic cleaning in monochlorobenzene for 10 minutes to dissolve and remove the entire charge transport layer.
Dry at 80 ° C. for 10 minutes.

Comparative Example 3 The reproduction of Comparative Example 3 was carried out in the same manner as in Example 1 except that the section of “3. Production of reproduced electrophotographic photosensitive member” was replaced with the following steps. An electrophotographic photoreceptor was manufactured. Further, a running test of the reproduced electrophotographic photosensitive member was performed in the same manner as in Example 1. The results are shown in Table 6 below.
Are shown together.

[0146] 3. Production of Reproduced Electrophotographic Photoreceptor The electrophotographic photoreceptor after the running test was subjected to ultrasonic cleaning for 5 minutes in a mixed solution of 50 parts of methyl alcohol and 40 parts of N, N-dimethylformamide, and then heated at 80 ° C. in hot water. For 5 minutes, and further immersed in cold water at 10 ° C. for 5 minutes to remove the photosensitive layer from the undercoat layer. After removing the photosensitive layer, the surface of the electrophotographic photoreceptor is brush-washed with distilled water, dried at 100 ° C. for 10 minutes, and similar to “1. Production of test electrophotographic photoreceptor” in Example 1. Then, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially laminated.

[Embodiment 4] 1. Production of Test Electrophotographic Photoreceptor In Example 1, "1. Production of Test Electrophotographic Photoreceptor"
An aluminum drum, a length of 340 mm,
A test electrophotographic photoreceptor was manufactured in the same manner as in Example 1 except that the outer diameter was 84 mm, and the section of (formation of charge generation layer) was changed to the following step.

(Formation of Charge Generation Layer) 4 parts of a bisazo compound represented by the following structural formula (b) as a charge generation material was
The mixture was pulverized with a ball mill in a mixed solvent of 40 parts of cyclohexane and 40 parts of n-butyl acetate to prepare a coating solution for forming a charge generation layer. This coating solution was applied onto the undercoating layer by dip coating, and dried by touch to form a 0.4 μm charge generating layer.

[0149]

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2. Running test The test electrophotographic photoreceptor thus obtained was mounted on a Fuji Xerox Co., Ltd., Vision 550 copier (the drum flange and the internal filler were removable), and the test chart was used. A print running test was carried out for up to 100,000 sheets in an environment of 20 ° C. and 40% with respect to the paper lateral feeding (using L paper manufactured by Fuji Xerox Co., Ltd.). The average thickness of the photosensitive layer after the running test was 15 μm, and the average surface roughness (Ra) of the reference line was 0.12 μm.

[0151] 3. Manufacture of Recycled Electrophotographic Photoreceptor (Precision Polishing) The electrophotographic photoreceptor after the running test is brushed with a nylon brush (a nylon brush, pile length 30 mm, thickness 10 denier, density 150 pcs / c).
m ² , and silicon oxide having a particle size of 30 μm dispersed in distilled water at 50 g / l is used as an abrasive)
The film thickness of the photosensitive layer after polishing was 14 μm, the film thickness variation was ± 0.8 μm, and the reference line average surface roughness (Ra) was 0.05.
Precision polishing was performed to a thickness of μm. After polishing, the surface of the remaining charge transport layer of the electrophotographic photoreceptor was brush-washed with distilled water and dried at 100 ° C. for 10 minutes.

(Formation of New Surface Layer) An electrophotographic photosensitive member which had been subjected to precision polishing and subsequent cleaning was used in Example 1.
In the same manner as described above, a charge transport layer (new surface layer) was formed again so that the film thickness of the entire photosensitive layer including the residual charge transport layer was 25 μm. As described above, the reproduced electrophotographic photosensitive member of Example 4 was manufactured.

4. Running Test of Reproduced Electrophotographic Photoreceptor The obtained regenerated electrophotographic photoreceptor was used and “4.
A print running test was performed in the same manner as in "Running Test of Reproduced Electrophotographic Photoconductor". A printing running test of 100,000 sheets was performed on the photosensitive drums thus obtained. The results are summarized in Table 6 below.

Example 5 The procedure of Example 4 was repeated, except that the section of (3. Production of Reproduced Electrophotographic Photoreceptor) (Formation of New Surface Layer) was changed to the following step. Thus, a reproduced electrophotographic photosensitive member of Example 5 was manufactured. Further, a running test of the reproduced electrophotographic photosensitive member was performed in the same manner as in Example 4. The results are summarized in Table 6 below.

(Formation of New Surface Layer) The following structural formula (e)
Is dissolved in 50 parts of cyclohexanone to prepare a coating solution for forming a new surface layer, wherein 1 part of the compound represented by the formula and 2 parts of the modified buret solution (solid content 67% by weight) represented by the structural formula (4) are dissolved. did. With respect to the electrophotographic photoreceptor that has been subjected to precision polishing and subsequent cleaning, the coating solution for forming a new surface layer is coated on the remaining charge transport layer by flow coating while the drum flange and the internal filler are kept as they are. After drying at room temperature for 10 minutes, the film was heated at 150 ° C. for 60 minutes to form a film having a thickness of 10 μm (14 μm of the photosensitive layer including the residual charge transporting layer).
(excluding μm) of the charge transport layer (new surface layer).

[0156]

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Here, the mixing ratio of the compound represented by the structural formula (e) and the burette-modified polyisocyanate represented by the structural formula (4) is represented by the following formula: Total number of moles of OH groups in the compound to be obtained]:
[Total number of moles of isocyanate groups in the buret-modified polyisocyanate represented by the structural formula (4)]
It is approximately 45:55.

Example 6 The procedure of Example 4 was repeated, except that the section of (3. Production of Reproduced Electrophotographic Photoreceptor) (Formation of New Surface Layer) was changed to the following step. Thus, a regenerated electrophotographic photosensitive member of Example 6 was produced. Further, a running test of the reproduced electrophotographic photosensitive member was performed in the same manner as in Example 4. The results are summarized in Table 6 below.

(Formation of New Surface Layer) In Example 3, a compound represented by the following structural formula (f) was used in place of the compound represented by the above structural formula (d), and a charge transporting layer was formed. A charge transport layer was formed in the same manner as in Example 3, except that the thickness of the (new surface layer) was 8 μm (excluding 14 μm of the photosensitive layer including the residual charge transport layer).

[0160]

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Table 6

[Table 6]

As shown in Table 6, according to the examples, it is found that a reproduced electrophotographic photosensitive member having image quality and durability equal to or better than that of a new article can be manufactured. In particular, in Examples 2, 3, 5, and 6 in which a charge transport layer (new surface layer) having high mechanical strength was formed, a reproduced electrophotographic photosensitive member capable of forming an image of good image quality for an extremely long period of time. You can see that the body can be manufactured.

On the other hand, in the reproduced electrophotographic photosensitive member of Comparative Example 1, the surface of the surface before the formation of the charge transporting layer was contaminated with extraneous matter such as toner which could not be removed by washing.
Since the charge transport layer (new surface layer) is formed thereon, it is considered that charges are injected into the charge transport layer and black spots are generated.

In the reproduced electrophotographic photoreceptor of Comparative Example 2, since the original charge transport layer was removed by the solvent, dissolution unevenness was generated, resulting in potential unevenness and image unevenness. it is conceivable that.

Further, in the regenerated electrophotographic photoreceptor of Comparative Example 3, the solvent was intended to remove the entire original photosensitive layer. However, it was difficult to completely remove the photosensitive layer with the solvent. Is considered to be the cause of the defect.

[0166]

As described above, according to the method for reproducing an electrophotographic photoreceptor of the present invention, a used electrophotographic photoreceptor can be formed by simply re-forming only a charge transport layer (or a surface protective layer). In addition, since a usable reproduction electrophotographic photosensitive member can be obtained, the reproduction is simple and easy, and the cost can be reduced by saving materials and shortening the steps.

Claims (5)

[Claims] An electrophotographic photosensitive member having at least a photosensitive layer on the surface of a conductive substrate is subjected to precision polishing so that a thickness variation after polishing is within a range of ± 1 μm or less. A method for reproducing an electrophotographic photoreceptor, comprising removing a photosensitive layer while keeping a film thickness, and then forming a new surface layer. 2. The method according to claim 1, wherein the new surface layer is a charge transport layer. 3. The method according to claim 1, wherein the new surface layer is a charge transport layer and a surface protection layer. 4. A reproduced electrophotographic photosensitive member reproduced by the method for reproducing an electrophotographic photosensitive member according to claim 1. 5. The reference line average roughness (R) of the surface after precision polishing
The reproduction electrophotographic photoreceptor according to claim 4, wherein a) is 0.1 μm or less.