JPH08123056A - Composition for charge transfer layer, laminated electrophotographic photoreceptor using same and production thereof - Google Patents

Abstract

PURPOSE: To provide a compsn. for a charge transfer layer which is suitable as a coating liquid to be used to form a laminated electrophotographic photoreceptor, and to improve electrostatic characteristics, wear resistance and mechanical strength of an electrophotographic photoreceptor obtd. by using this coating liquid. CONSTITUTION: This laminated electrophotographic photoreceptor is produced by laminating at least a charge generating layer and a charge transfer layer on a conductive supporting body. The compsn. for the charge transfer layer used as a coating liquid to form the charge transfer layer of this photoreceptor is prepared by dissolving a phenylstilbene compd. expressed by formula I and a fluorene polycarbonate resin as a binder resin in a solvent. The fluorene polycarbonate consists of the repeating unit expressed by formula II and the repeating unit expressed by formula III. In formula, R1 is hydrogen or methoxy group, R2 is hydrogen, methyl group or ethyl group, and R3 is hydrogen, methyl group, ethyl group, or propyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a charge transport layer used for producing a laminated electrophotographic photoreceptor, a laminated electrophotographic photoreceptor obtained by using the composition, and a method for producing the photoreceptor. More specifically, the present invention relates to a laminated type electrophotographic photoconductor that maintains excellent mechanical strength and electrophotographic characteristics and can be suitably used in various electrophotographic fields.

[0002]

2. Description of the Related Art In recent years, as an electrophotographic photoreceptor, an organic photoreceptor containing an organic photoconductive substance has been developed and put into practical use. This has advantages such as easy film formation, low cost and no pollution. Especially, an optical printer such as a laser beam printer using a semiconductor laser as a light source,
The development of organic photoconductors having high sensitivity in the long wavelength region suitable for facsimiles is remarkable.

Most of the practically used organic photoconductors are laminated organic photoconductors in which a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance are laminated. The configuration of separation has significantly improved the characteristics.

This laminated type electrophotographic photoreceptor is generally composed of
It is configured by forming a thin film charge generation layer on a conductive support, and forming a relatively thick film charge transport layer on it.The charge generation layer absorbs light to generate carriers, Carriers injected into the transport layer move in the charge transport layer and neutralize the surface charge, thereby exhibiting a function. In this case, the charge transport layer has a function of moving the injected carriers, a function of retaining the charging ability (receptive potential) of the photoconductor, and a function of maintaining the mechanical strength of the photosensitive layer.

In this charge transport layer, as a charge transport material,
Generally, a substance having a high charge transporting ability such as a hydrazone compound, a stilbene compound, and a butadiene compound is used. For example, as to the hydrazone compound, Japanese Patent Laid-Open No.
-81847, JP-A-55-89443,
JP-A-57-190951, JP-A-58-159
536 and the like, and stilbene compounds are disclosed in JP-A-58-189145 and JP-A-58-19.
0953, JP-A-58-198425, JP-A-58-198043 and the like, and butadiene compounds are disclosed in JP-A-62-30255 and JP-A-62-287257. Has been done.

On the other hand, the electrophotographic photosensitive member naturally has a predetermined electrostatic characteristic according to the electrophotographic process applied,
In the case of a photoconductor that is required to have optical characteristics and can be repeatedly used, the surface layer of the photoconductor has corona charging, toner development, paper and paper in various processes in an electrophotographic apparatus. Since electrical and mechanical external forces such as transfer to the surface and cleaning treatment are directly applied, durability against them is required. Specifically, image blur caused by deterioration of the photosensitive layer due to the action of ozone or its nitrogen oxides generated during corona charging, increase in residual potential, and surface abrasion or scratches due to rubbing of toner or cleaning blade Electrical and mechanical durability against generation is required.

Further, since the laminated type electrophotographic photosensitive member is usually constructed by laminating the charge transport layer on the charge generation layer, the durability of the outermost charge transport layer is important. Usually, the charge transport layer is formed by uniformly dispersing the charge transport material in the binder resin, so the mechanical strength is greatly affected by the strength of the binder resin, and a binder resin having excellent mechanical strength is demanded. There is. Recently, as a resin satisfying these requirements, a polycarbonate resin has been proposed and used as a binder of a charge transport layer (for example, JP-A-59-71057 and JP-A-60-172045). JP-A-60-
192950).

[0008]

As described above, in actual use, the life of the electrophotographic photoreceptor is determined not only by the electrostatic characteristics but also by the mechanical durability as described above.

However, as described above, although various studies have been made to improve the binder resin for improving the mechanical durability and the charge transporting material for improving the electrostatic characteristics, the binder resin and the charge transporting material have been studied. At present, almost no studies have been made on various problems related to compatibility with.

For example, when the charge transport layer is formed by the dip coating method, the pot life is required to be long and stable as the characteristics of the coating solution, and the crystal is formed in the coating film after the charge transport layer is formed. The characteristic of the binder resin that does not occur is also required.

For example, when a charge transport layer is formed by using a polycarbonate resin made of bisphenol A as a binder resin, it has been clarified that there are the following two problems.

The first problem is that, when the charge transporting coating material is applied at the time of preparing the photoreceptor, the coating solution may gel or the charge transporting layer may easily crystallize depending on the solvent used. There is no light attenuation in the part where this crystallization has occurred, and the electric charge remains as a residual potential and appears as noise on the image.

A second problem is that the charge transport layer using a polycarbonate resin containing bisphenol A as a raw material has poor adhesion to the base and is easily peeled off, or has a low surface hardness to cause scratches or wear on the surface. As a result, the printing life is shortened.

In view of the above conventional problems, the present invention pays attention to the compatibility between the binder resin and the charge transport material, and by using a specific binder resin, the electrostatic characteristics of the laminated electrophotographic photoreceptor can be improved. To provide a laminated type electrophotographic photoreceptor having good mechanical and electrostatic properties, which not only improves the abrasion resistance and mechanical strength of the charge transport layer but also enables the coating liquid to have a long life. That is the purpose.

[0015]

SUMMARY OF THE INVENTION From the above viewpoints, the present inventors have made various studies on the compatibility of the charge transport material and the binder resin, and completed the present invention.

That is, the composition for a charge transport layer of the present invention is the same as the charge transport layer of a laminated type electrophotographic photosensitive member comprising a conductive support and at least a charge generation layer and a charge transport layer laminated on the conductive support. The one used in the formation, the general formula

[0017]

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(Wherein R ₁ represents hydrogen or a methoxy group) and a phenylstilbene compound represented by the general formula

[0019]

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(Wherein R ₂ represents hydrogen, a methyl group or an ethyl group), and a general formula

[0021]

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(In the formula, R ₃ is hydrogen, a methyl group,
And a fluorene polycarbonate resin as a binder resin comprising a repeating unit represented by the formula (1), which represents an ethyl group or a propyl group).

The laminated electrophotographic photoreceptor of the present invention comprises a charge transport layer formed by using the composition for a charge transport layer of the present invention.

Further, the method for producing a laminated electrophotographic photoreceptor of the present invention forms a charge transport layer by using the composition for a charge transport layer of the present invention as a coating solution.

[0025]

That is, the fluorene polycarbonate resin of the present invention has a very high compatibility with the charge transport material, and by using the fluorene polycarbonate resin of the present invention as the binder resin of the charge transport layer, a laminated type electrophotographic photoreceptor is obtained. It is possible to not only improve the mechanical strength, abrasion resistance and electrostatic properties of the above, but also prolong the service life of the coating liquid comprising the charge transport layer composition.

[0026]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a laminated type electrophotographic photosensitive member according to an embodiment of the present invention.

The laminated electrophotographic photoreceptor 1 is constructed by laminating an organic photosensitive layer 3 comprising a charge generation layer 4 and a charge transport layer 5 on a conductive support 2. The charge transport layer 5 is
It is composed of at least a charge transport material and a binder resin.

The composition for charge transport layer of the present invention is used when forming the charge transport layer 5, and has the following composition.

That is, the composition for charge transport layer of the present invention has the general formula

[0031]

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(Wherein R ₁ represents hydrogen or a methoxy group) and a phenylstilbene compound represented by the general formula

[0033]

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(Wherein R ₂ represents hydrogen, a methyl group or an ethyl group) and a general formula

[0035]

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(In the formula, R ₃ is hydrogen, a methyl group,
And a fluorene polycarbonate resin as a binder resin comprising a repeating unit represented by the formula (1), which represents an ethyl group or a propyl group).

This fluorene polycarbonate resin is
The general formula

[0038]

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The content of the repeating unit represented by

[0040]

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The repeating unit represented by

[0042]

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If the molar ratio with respect to the total of the repeating units represented by the formula exceeds 0.5, the abrasion resistance is deteriorated.
The molar ratio is preferably 0.5 or less.

The fluorene polycarbonate resin used in the present invention has the general formula

[0045]

[Chemical 4]

(Wherein R ₂ represents hydrogen, a methyl group or an ethyl group) and a bisphenolfluorene compound represented by the general formula

[0047]

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(In the formula, R ₃ is hydrogen, a methyl group,
Ethyl group or propyl group is shown), for example, by a transesterification method in which diphenyl carbonate is reacted in a molten state with a dihydric phenol compound represented by, or in the presence of a hydrogen chloride binder such as pyridine. It can be obtained by reacting with phosgene in a suitable solvent.

In view of the characteristics as an electrophotographic photoreceptor, when the content of the binder resin in the charge transport layer is high, the mechanical strength is improved but the sensitivity is lowered. On the contrary, when it is too low, the sensitivity is improved but the mechanical strength is improved. Strength decreases. Therefore, the content of the binder resin is preferably 40% by weight or more and 60% by weight or less, more preferably about 50% by weight, based on the total amount of the charge transport layer.

Further, the solvent of the present invention may be any solvent which can dissolve the charge transporting substance and the binder resin, and specific examples thereof include halogenated hydrocarbons, aromatic hydrocarbons, ketones, esters, Ethers and the like can be used.

The charge generating layer 4 is composed of at least a charge generating substance and a binder resin. As the charge generating substance,
Various pigments or dyes such as azo-based, phthalocyanine-based, squarylium-based, cyanine-based, quinone-based, and perylene-based pigments are listed, and oxotitanium phthalocyanine pigments are preferable in order to enhance electrostatic properties.

As the binder resin for the charge generation layer 4,
Examples thereof include polyester, polyvinyl chloride, polyvinyl butyral, polyvinyl acetate, polycarbonate, and copolymers of these resins. As a solvent,
Any material that can dissolve the binder resin may be used, and specifically, halogenated hydrocarbons, aromatic hydrocarbons, ketones, esters, ethers, alcohols and the like can be used.

The conductive support 2 may be any conventionally known one having conductivity, and examples thereof include metal materials such as aluminum, iron and copper, conductive plastics (including phenol resin) and iodine. Glass coated with a conductive material such as aluminum iodide, copper iodide, chromium oxide, or tin oxide is used.

Next, a method of manufacturing the laminated electrophotographic photosensitive member 1 will be described.

The charge generating layer 4 contains the above charge generating substance,
A coating material dispersed in a solution in which a binder resin is dissolved is used to apply a dip coating method, a spin coating method, on the conductive support 2.
It is formed by a spray coating method or an electrostatic coating method.

Due to the characteristics, the thickness of the charge generation layer 4 is 0.
About 1 to 1 μm is preferable. If the film thickness is too thin, the amount of electric charge generated is small and sufficient sensitivity cannot be obtained. Conversely, if it is too thick,
The chargeability is reduced, and the chargeability and the repeated stability of sensitivity are impaired.

Further, when the charge generating layer 4 is formed on the conductive support 2, the adhesion between the conductive support 2 and the charge generating layer 4 is improved or charge injection from the conductive support 2 side is prevented. Therefore, it is also possible to provide a layer of 0.1 to 1 μm made of polyvinyl butyral resin, vinyl acetate resin or polyamide resin.

The charge transport layer 5 is formed on the charge generation layer 4 preferably by a dip coating method using the above composition for a charge transport layer as a coating liquid. The thickness of the charge transport layer 5 is
From the characteristics, about 5 to 30 μm is preferable. If the film thickness is too thin, the chargeability will decrease, and conversely, if it is too thick, the sensitivity will decrease.

The charge transport layer composition of the present invention, the laminated electrophotographic photoreceptor obtained by using the composition, and the method for producing the photoreceptor have been described in detail above.

Hereinafter, further details will be described based on specific examples.

Example 1 4 parts by weight of τ type metal-free phthalocyanine (manufactured by Toyo Ink Manufacturing Co., Ltd.), butyral resin (manufactured by Sekisui Chemical Co., Ltd., trade name S-lex BL)
-1) 3 parts by weight were dispersed in 80 parts by weight of tetrahydrofuran. This coating solution was applied onto an aluminum plate by dip coating and dried at 100 ° C. for 1 hour to form a charge generation layer having a film thickness of 0.1 μm.

Next, 4-N, N-diphenylamino-α
-2 parts by weight of phenylstilbene and the general formula

[0063]

[Chemical 6]

The repeating unit represented by

[0065]

[Chemical 7]

And a repeating unit represented by the general formula

[0067]

[Chemical 6]

A composition for a charge transport layer was prepared by dissolving 2 parts by weight of a fluorene polycarbonate resin having a content of repeating units represented by the formula of 20 mol% in 20 parts by weight of dichloromethane as a composition for a charge transport layer. The coating solution was applied onto the charge generation layer by dip coating and dried at 100 ° C. for 1 hour to form a charge transport layer having a film thickness of 20 μm.

Using the electrophotographic photosensitive member sample thus obtained, a sandpaper abrasion test and an electrostatic property evaluation were conducted under a room temperature environment (20 ° C., 60% RH).

The sandpaper abrasion test was conducted by using an abrasion tester (Peeling / Slipping /
Scratching TESTER HEIDON-
14) using a sandpaper (1200
No. SANKYO) and repeatedly rubbed at 30 mm / mim, and the relationship between the number of repetitions and the amount of wear at that time is evaluated. However, the wear amount is the product of the width and the depth when the charge transport layer is scraped in this evaluation.

The electrostatic characteristics were evaluated for initial potential characteristics and repetitive characteristics using a potential characteristic evaluation device (EPA-8100 manufactured by Kawaguchi Electric Co., Ltd.).

This is a corona current of -30 μ in a dark place.
The charging potential when the photoreceptor sample is charged by corona discharge by A is set to V0, and then monochromatic light with energy of 2.1 μJ / cm ² · sec having a peak at 800 nm is irradiated,
Exposure amount E1 required to reduce the surface potential to 1/2 V0
The residual potential VR at / 2 and 2 seconds after exposure was also measured.

The evaluation results are shown in the first row of Table 1 below.

At the same time, a standing test was conducted on the charge transport layer composition, and the change with time of the coating material was evaluated by visual observation.

The evaluation results are shown in the first row of Table 2 below.

Example 2 The fluorene polycarbonate resin of Example 1 has the general formula

[0077]

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A repeating unit represented by the general formula

[0079]

[Chemical 7]

And a repeating unit represented by the general formula

[0081]

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A charge generation layer and a charge transport layer were formed on the conductive support in the same manner as in Example 1 except that the fluorene polycarbonate resin was used in which the content of the repeating units represented by After being formed, the sandpaper abrasion test, the electrostatic property evaluation, and the change with time of the paint were evaluated in the same manner as in Example 1.

The results are shown in the second row of Tables 1 and 2, respectively.

Example 3 Conductivity was the same as in Example 1 except that α-type oxotitanium phthalocyanine was used in place of τ-type metal-free phthalocyanine as the charge-generating material in the charge generation layer of Example 1. A charge generation layer and a charge transport layer were formed on the support, and electrostatic properties were evaluated in the same manner as in Example 1.

The results are shown in the third row of Table 1.

Example 4 In the charge transport layer of Example 1, 4- (Np-p- was used as the charge transport material instead of 4-N, N-diphenylamino-α-phenylstilbene.
Methoxyphenyl-N-phenyl) amino-α-phenylstilbene is used as a fluorene polycarbonate resin and is represented by the general formula

[0087]

[Chemical 6]

A charge generating layer and a charge transporting layer were formed on a conductive support in the same manner as in Example 1 except that the fluorene polycarbonate resin was used in which the content of the repeating units represented by After being formed, the sandpaper abrasion test, the electrostatic property evaluation, and the change with time of the paint were evaluated in the same manner as in Example 1.

The results are shown in the fourth row of Table 1 and the third row of Table 2, respectively.

(Comparative Example 1) As a comparative example of the present invention, a binder resin for the charge transport layer was obtained from 2,2-bis (4-hydroxyphenyl) propane instead of the fluorene polycarbonate resin of Example 1. A charge generation layer and a charge transport layer were formed on the conductive support in the same manner as in Example 1 except that the bisphenol A type polycarbonate resin was used. The characteristic evaluation and the change with time of the coating material were evaluated.

The results are shown in the fifth row of Table 1 and the fourth row of Table 2, respectively.

[0092]

[Table 1]

[0093]

[Table 2]

As is clear from Table 1, the laminated type electrophotographic photoreceptor obtained by using the composition for charge transport layer of the present invention is excellent in mechanical strength, abrasion resistance and electrostatic characteristics, and As is clear from Table 2, the composition for a charge transport layer of the present invention is stable without gelation, and when used as a coating liquid, it is possible to prolong the service life thereof.

[0095]

INDUSTRIAL APPLICABILITY As described above, the charge transport layer composition of the present invention does not cause gelation of the coating liquid when used as a coating liquid when forming a laminated type electrophotographic photoreceptor. A laminated type electrophotographic photoreceptor obtained by using the composition for a charge transport layer of the present invention, which can perform stable coating, has improved electrostatic properties, abrasion resistance and mechanical strength. ,
It has excellent printing durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a laminated type electrophotographic photosensitive member according to an embodiment of the present invention.

[Explanation of symbols]

 1 Laminated Electrophotographic Photoreceptor 2 Conductive Support 3 Photosensitive Layer 4 Charge Generation Layer 5 Charge Transport Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 5/05 101 102

Claims (6)

[Claims] 1. A composition for a charge-transporting layer used when forming the charge-transporting layer of a laminated-type electrophotographic photosensitive member comprising a conductive support and at least a charge-generating layer and a charge-transporting layer laminated on the conductive support. The product has the general formula: (Wherein, R ₁ represents hydrogen or a methoxy group), and a phenylstilbene compound represented by the general formula: (In the formula, R ₂ represents hydrogen, a methyl group or an ethyl group) and a repeating unit represented by the general formula: (Wherein R ₃ represents hydrogen, a methyl group, an ethyl group or a propyl group) and a fluorene polycarbonate resin as a binder resin composed of a repeating unit represented by the following formula: A composition for a charge transport layer, which is characterized by being: 2. The above general formula: The content ratio of the repeating unit represented by And a repeating unit represented by the above general formula: The molar ratio to the total of the repeating units represented by
The composition for a charge transport layer according to claim 1, which is 5 or less. 3. A laminate type electrophotographic photosensitive member comprising a conductive support and at least a charge generation layer and a charge transport layer laminated on the conductive support, wherein the charge transport layer is the charge of claim 1 or 2. A laminated electrophotographic photoreceptor, which is formed using the composition for a transport layer. 4. The laminated electrophotographic photoreceptor according to claim 3, wherein the charge generating substance in the charge generating layer is an oxotitanium phthalocyanine pigment. 5. A method for producing a laminated type electrophotographic photosensitive member comprising a conductive support and at least a charge generation layer and a charge transport layer laminated on the conductive support, the charge transport layer according to claim 1 or 2. A method for producing a laminated type electrophotographic photoreceptor, which comprises forming the charge transport layer by using the composition as a coating solution. 6. The method for producing a laminated electrophotographic photoreceptor according to claim 5, wherein the charge generating substance in the charge generating layer is an oxotitanium phthalocyanine pigment.