JPH0627708A - Electrophotographic photosensitive material - Google Patents

Abstract

PURPOSE:To prevent the wear of a photosensitive layer and the occurrence of an abnormal image without casusing the crystallization of charge-transfer material by forming a protective layer by dispersing conductive particulates in phosphagen setting resin. CONSTITUTION:In an electrophotographic photosensitive material in which a charge- production/charge-transfer function separative photosensitive layer is provided on a conductive base material and also an intermediate layer and a protective layer are laminated, the protective layer is formed by dispersing conductive particulates in phosphagen setting resin. In this case, as an example of the phosphagen setting resin, that which has been shown by the formula is representatively used. As the function separative photosensitive layer, that in which materials having charge- production and charge-transfer functions have been mixed in a single layer may be used, and that which charge-production layers and charge-transfer layers are successively laminated in this order may be used, and also that in which charge-transfer layers and charge-production layers are laminated in the reverse order may be used. Even in the case where the charge-production layer is placed above, plenty of charge-transfer material oozes out in the charge-production layer when the charge-production layer is coated, and in any case, the charge-transfer material exists on the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member having a function-separated photosensitive layer.

[0002]

2. Description of the Related Art It is known to provide a protective layer on the surface for the purpose of improving the abrasion resistance of an electrophotographic photoreceptor. Specifically, a protective layer using polyurethane as a binder resin is provided (see JP-A-58-122553), and a protective layer using a curable silicone resin as a binder resin is provided (JP-A-61-51155). It is known to provide a protective layer using polyetherimide as a binder resin (see JP-A-2-161449).

[0003]

When a polyurethane resin is used as the conventional protective layer, image deletion occurs due to a decrease in surface resistance in a high humidity environment. When a curable silicone resin is used, the residual potential easily rises, and when repeated copying is performed, the background stain occurs early.
Further, when polyetherimide is used, sensitivity deterioration and residual potential are large, and background stain occurs.

An object of the present invention is to provide an electrophotographic photosensitive member which prevents abrasion of the photosensitive layer without causing these electrophotographic characteristic problems.

[0005]

SUMMARY OF THE INVENTION The present invention provides an electrophotographic photosensitive member comprising a conductive support, on which a photosensitive layer having function separation for charge generation and charge transfer is provided, and an intermediate layer and a protective layer are further laminated. The electrophotographic photosensitive member is characterized in that the protective layer is formed by dispersing conductive fine particles in a phosphazene-based cured resin.

The following structural formula (I) is typically used as an example of the phosphazene-based cured resin used in the present invention.

[0007]

[Chemical 1]

The function-separated photosensitive layer in the present invention may be a single layer in which materials having a function of generating charge and a function of transferring charge are mixed, but a charge generating layer and a charge transfer layer may be sequentially laminated. Good. Alternatively, the reverse charge transfer layer and the charge generation layer may be laminated in this order. Even when the charge generation layer is on the top, the charge transfer substance is exuded into the charge generation layer during coating and a large amount of the charge transfer substance is present. Exists on the surface.

The above structural formula used for the protective layer in the present invention
The compound (I) has a higher hardness and excellent abrasion resistance than conventional curable resins and thermoplastic resins. However, since this resin has poor compatibility with the charge transfer substance, when a protective layer is formed by directly coating on the layer containing the charge transfer substance, crystallization of the charge transfer substance occurs and the background stain due to sensitivity decrease. And abnormalities such as point defects occur. Therefore, when the protective layer is provided via the intermediate layer, crystallization of the charge transfer substance does not occur, the advantage of the phosphazene resin is utilized, and an abnormal image does not occur.

Further, as a result of studying the intermediate layer, it was found that when a polyamide or an acrylic anilide resin was used as the intermediate layer, stable potential characteristics were exhibited even when it was repeatedly used for a very long time and no abnormal image was generated.

Specific examples of the polyamide used for the intermediate layer include nylon 6, nylon 66 and nylon 61.
0, nylon 612, nylon 11, nylon 12, nylon MXD6, nylon 46, methoxymethylated polyamide and the like.

The acrylanilide resin is a homopolymer or a copolymer containing acrylanilide or a derivative of acrylanilide as a monomer unit. A typical example of the acrylic anilide monomer is represented by the following general formula (II).

[0013]

[Chemical 2]

(However, R ₁ : hydrogen or a methyl group, R ₂ :
Hydrogen, alkyl group, hydroalkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted aralkyl group, R ₃ , R ₄ , R ₅ , R ₆ , R ₇ : hydrogen, alkyl group, alkoxy group, hydroxy group , Nitro group, nitroso group, cyano group, carboxyl group, alkoxycarbonyl group, acyl group, sulfonyl group, amino group, substituted amino group, halogen or trifluoromethyl group) of the monomer represented by the above general formula (II) Examples are shown in Table 1 below. These polyamides,
The acrylic anilide resin can be used alone or in combination of these, or can be used as a mixture with other known resins.

[0015]

[Table 1]

The thickness of the intermediate layer is preferably 0.05 μm or more and 1 μm or less, more preferably 0.1 μm or more and 0.4 μm.
m or less is preferable. If it exceeds 1 μm, the residual potential is large and the background stain may occur. If the thickness is less than 0.05 μm, when the protective layer is applied, the function as a barrier layer for preventing the charge generation layer and the charge transport layer from being damaged is weakened, and abnormal images such as point defects may occur.

The protective layer is made by dispersing conductive fine particles in the phosphazene-type curable resin represented by the structural formula (I), and the conductive fine particles are made of tin oxide, titanium oxide, indium oxide, A metal oxide such as antimony oxide is preferable, and the content of these conductive fine particles is 50% by weight or more and 70% by weight or more based on the phosphazene-based curable resin.
The following is preferable, and 55 to 65% by weight is more preferable. If it exceeds 70% by weight, the surface resistance is lowered and image deletion tends to occur, and if it is less than 50% by weight, the residual potential is apt to rise, which leads to background stain.

The thickness of the protective layer is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 5 μm or less. When it exceeds 10 μm, the residual potential is large and the background is stained. If it is less than 1 μm, it has poor mechanical strength and is easily scratched by repeated use, and abnormal images such as black streaks occur.

In the present invention, an undercoat layer which is usually used may be provided on the conductive support, if necessary.

The conductive substrate is intended to supply a charge having a polarity opposite to that of the charged charge to the substrate side and has an electric resistance of 10 ¹⁰ Ωcm or less and an undercoat layer, charge generation and charge. Any material that can withstand the film forming conditions of the moving layer can be used. Examples of these are Al, Ni, C
The surface of r, Zn, electrically conductive metals and alloys such as stainless steel, inorganic insulating substances such as glass and ceramics, and organic insulating substances such as polyester, polyimide, phenol resin, polyamide, and paper are vacuum-deposited, sputtered, and sprayed. Depending on the method of painting, Al, Ni, C
Examples thereof include those obtained by coating with an electrically conductive substance such as r, Zn, stainless steel, carbon, SnO ₂ , In ₂ O _{3 and the} like for conducting a conductive treatment.

The charge generating layer is composed of only the charge generating substance or a resin layer in which the charge generating substance is dispersed or compatible.

As the charge generating substance, for example, CI Pigment Blue 25 (CI (Color Index) 2
1180), CI Pigment Red 41 (CI21
100), CI Acid Red 52 (CI4510
0), CI Basic Red 3 (CI4521)
0), a phthalocyanine pigment having a porphyrin skeleton, an azurenium salt pigment, a squalic salt pigment, an anthanthansulon pigment, an azo pigment having a carbazole skeleton (described in JP-A-53-95033), and a stilbene skeleton. Azo pigments (JP-A-53-1382)
29), an azo pigment having a triphenylamine skeleton (described in JP-A-53-132547),
Azo pigment having a dibenzothiophene skeleton
No. 21728), an azo pigment having an oxadiazole skeleton (described in JP-A-54-12742), and an azo pigment having a fluorenone skeleton (JP-A-54).
No. 22834), an azo pigment having a bisstilbene skeleton (described in JP-A-54-17733), an azo pigment having a distyryl oxadiazole skeleton (described in JP-A-54-2129). , A trisazo pigment having a distyrylcarbazole skeleton (JP-A-54
No. 17734), a trisazo pigment having a carbazole skeleton (described in JP-A-57-195767), and CI Bad Brown 5 (CI7341).
0), indigo-based pigments such as CI Bad Dye (CI73030), and perylene-based pigments such as Argol Scarlet B and Indus Scarlet R (manufactured by Bayer) can be used.

The thickness of the charge generation layer is suitably about 0.05 to 2 μm, preferably 0.1 to 1 μm.

The charge generating layer is formed by dispersing or compatibilizing the charge generating substance together with a resin binder in a suitable solvent, and coating and drying this on the substrate or on the undercoat layer.

Such resin binders include polystyrene, styrene-butadiene copolymer, styrene-
Acrylonitrile copolymer, styrene-maleic anhydride copolymer, polyester, polyarylate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyacrylate, polycarbonate, cellulose acetate resin, Ethyl cellulose resin, polyvinyl butyral, polyvinyl acetal, polyvinyl benzal, polyvinyl formal, phenoxy resin, polyvinyl pyridine, poly-N-vinyl carbazole, acrylic resin, silicone resin, nitrile rubber,
Examples thereof include thermoplastic or thermosetting resins such as chloroprene rubber, butadiene rubber, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. These binder materials may be used alone or as a mixture.

As the solvent, benzene, toluene, xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, ethyl alcohol, methyl alcohol, butyl alcohol, isopropyl alcohol, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexane. , Methyl cellosolve, ethyl cellosolve, etc., and these solvents can be used alone or in combination.

The charge transfer layer can be formed by dissolving or dispersing the charge transfer substance and the resin binder in a suitable solvent, and coating and drying the solution. If necessary, a plasticizer, a leveling agent, a wear resistance enhancing material, etc. can be added.

Examples of the charge transfer substance include poly-N-carbazole and its derivative, poly-γ-carbazolyl ethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene, oxazole derivative and imidazole. Derivatives, triphenylamine derivatives, and JP-A-55-154955, 55-156954, 55-5
2063, 56-81850, 51-10983, 5
1-94829, 52-128373, 56-2924
5, 58-58552, 57-73075, 58-19
8043, 49-105537, 52-139066,
The charge transfer substances described in JP-A No. 52-139065 can be used.

It is possible that the charge generating substance and the charge transfer substance are mixed in a single layer.

[0030]

EXAMPLES The present invention will be described below based on examples.

Example 1 An undercoat layer having a thickness of about 3 μm was formed on an 80 mmφ aluminum cylinder by dip coating and heating and drying the following undercoat layer coating solution.

(Coating liquid for undercoat layer) Alkyd resin (Beckolite M-6401, manufactured by Dainippon Ink and Chemicals) 3 parts by weight Melamine resin (Super Beckamine G-821, manufactured by Dainippon Ink and Chemicals) 2 parts by weight TiO ₂ (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.) 30 parts by weight A liquid consisting of 15 parts by weight of methyl ethyl ketone was dispersed for 24 hours, and then diluted with methyl ethyl ketone / isopropyl alcohol = 11/9 parts by weight to obtain a coating liquid for undercoat layer. did.

Onto this, a cyclohexanone dispersion of the following azo pigment (III) was applied by dip coating and dried by heating to about 0.1 μm.
The charge generation layer of was formed.

[0034]

[Chemical 3]

Next, a charge transfer substance (D) represented by the following structural formula (IV) and a viscosity average molecular weight 2 represented by the following structural formula (V)
With various binder resins (R), D / R = 9/10
(Weight ratio), solid content concentration 18% (solvent: adjusted to methylene chloride, silicon oil (KF-50,
A charge transfer layer coating solution containing 0.1% (R ratio) of Shin-Etsu Silicone Co., Ltd. was applied onto the charge generation layer by dip coating and heat drying to form a charge transfer layer of about 25 μm.

[0036]

[Chemical 4]

On top of this, a mixed solution of 5 parts by weight of methoxymethylated polyamide (Toresin F30, manufactured by Teikoku Kagaku) and 10 parts by weight of quaternary copolymerized nylon (CM8000, manufactured by Toray) (solvent: methanol: 1-butanol). = 7/3
(Weight ratio) is 0.2 μm after spray coating and heat drying.
m intermediate layers were provided.

Furthermore, 60 parts by weight of tin oxide fine powder (manufactured by Mitsubishi Materials) is dispersed in 40 parts by weight of the phosphazene type thermosetting resin (Idemitsu PPZ manufactured by Idemitsu Petrochemical Co., Ltd.) represented by the structural formula (II). The resulting tetrahydrofuran dispersion was spray-coated and dried by heating to form a protective layer of 5 μm to prepare an electrophotographic photoreceptor.

Example 2 A phosphazene type thermosetting resin used for the protective layer was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 50 parts by weight of tin oxide fine powder was used.

Example 3 A phosphazene type thermosetting resin used in the protective layer was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the weight part and the tin oxide fine powder were 70 parts by weight. Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the tin oxide fine powder used in the protective layer was changed to indium oxide fine powder (manufactured by Mitsubishi Materials).

Example 5 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the tin oxide fine powder used in the protective layer was changed to tin oxide-coated titanium oxide fine powder (manufactured by Titanium Industry Co., Ltd.). .

Example 6 No. The homopolymer obtained by polymerizing the 15 monomers was dissolved in a mixed solvent of ethanol / 1-butanol = 1/1 (weight ratio) and spray-coated and heated and dried using a coating solution for intermediate layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that an intermediate layer having a film thickness of 0.3 μm was provided.

Example 7 A phosphazene type thermosetting resin used for the protective layer was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 40 parts by weight of tin oxide fine powder was used. Example 8 A phosphazene type thermosetting resin used for the protective layer was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the weight part and the tin oxide fine powder were 80 parts by weight. Example 9 Melamine resin (Super Beckamine G-821-60,
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that an isobutanol solution (manufactured by Dainippon Ink and Chemicals, Inc.) was sprayed and dried by heating to form an intermediate layer having a film thickness of 0.5 μm.

Comparative Example 1 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the intermediate layer was not provided.

Comparative Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the intermediate layer and the protective layer were not provided.

Comparative Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the binder resin used in the protective layer was changed to polyetherimide (Ultem 1000, manufactured by Engineering Plastics Co., Ltd.).

The electrophotographic photosensitive member obtained as described above was mounted on a commercially available copying machine (Recopy FT4820, manufactured by Ricoh Co., Ltd.), and a 100,000-copy test was conducted to evaluate images. The results are shown in Table 2.

[0048]

[Table 2]

Example 10 A charge transfer substance (D) represented by the following structural formula (VI) and a binder resin (R) represented by the following structural formula (VII) and having a viscosity average molecular weight of 30,000 were D / R = 8. / 10 (weight ratio) and a solid content concentration of 17% (solvent: methylene chloride), and then silicone oil (KF-50, manufactured by Shin-Etsu Silicone Co., Ltd.) was added at 0.02% (ratio to R). The coating liquid for charge transfer layer was applied onto an aluminum cylinder of 80 mmφ by dip coating and dried by heating to form a charge transfer layer of about 22 μm.

[0050]

[Chemical 5]

Onto this, a cyclohexanone dispersion of the following azo pigment (VIII) was spray coated and dried by heating to about 0.2.
A charge generation layer of μm was formed.

[0052]

[Chemical 6]

On top of this, quaternary copolymer nylon (CM800
0, manufactured by Toray Industries, Inc.) in a methanol / 1-butanol mixed solution (methanol: 1-butanol = 7/3 (weight ratio)) was spray coated and dried by heating to form a 0.2 μm intermediate layer.

Further, a tetrahydrofuran dispersion liquid obtained by dispersing 70 parts by weight of the tin oxide-coated titanium oxide fine powder in 30 parts by weight of the phosphazene type thermosetting resin is spray-coated and dried by heating to dryness to a thickness of 3 μm. Layers were provided to prepare an electrophotographic photoreceptor. Example 11 An electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that the titanium oxide fine powder used in the protective layer was changed to the indium oxide fine powder.

Example 12 An electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that the titanium oxide fine powder used in the protective layer was changed to the tin oxide fine powder.

Example 13 50 parts of phosphazene type thermosetting resin used for the protective layer was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that 50 parts by weight of titanium oxide fine powder was used.

Example 14 60% of the phosphazene type thermosetting resin used for the protective layer was used.
An electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that 40 parts by weight of titanium oxide fine powder was used.

Example 15 No. The homopolymer obtained by polymerizing the monomer 1 was dissolved in a mixed solvent of ethanol / 1-butanol = 1/1 (weight ratio), spray-coated and heated and dried using a coating solution for intermediate layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that an intermediate layer having a film thickness of 0.3 μm was provided.

Example 16 A phosphazene type thermosetting resin used for the protective layer was used.
An electrophotographic photoreceptor was prepared in the same manner as in Example 10 except that 40 parts by weight of tin oxide-coated titanium oxide fine powder was used.

Example 17 A phosphazene type thermosetting resin used for the protective layer was used.
An electrophotographic photoreceptor was prepared in the same manner as in Example 10 except that 80 parts by weight of tin oxide-coated fine titanium oxide powder was used.

Example 18 An electrophotographic photosensitive member was prepared in the same manner as in Example 5 except that an intermediate layer was prepared by using a phenol resin (Priofen J-325, manufactured by Dainippon Ink and Chemicals, Inc.).

Comparative Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that the intermediate layer was not provided.

Comparative Example 5 An electrophotographic photosensitive member was prepared in the same manner as in Example 10 except that the intermediate layer and the protective layer were not provided.

Comparative Example 6 Example 5 was repeated except that the binder resin for the protective layer was changed to silicone resin (Tosguard 510, manufactured by Toshiba Silicone Co.).
An electrophotographic photoreceptor was prepared in the same manner as in.

The electrophotographic photoconductors of Examples 10 to 18 and Comparative Examples 4 to 6 were mounted on a remodeling machine of a commercially available copying machine which was remodeled into a positive charging system, and a 100,000-sheet copying test was conducted to evaluate images. The results are shown in Table 3.

[0066]

[Table 3]

[0067]

In the present invention, since the phosphazene-based curable resin represented by the structural formula (I) is used as the binder resin of the protective layer, it is excellent in abrasion resistance and wears the photosensitive layer even if it is repeatedly used. Since the sensitivity does not decrease, a good image without an abnormal image such as background stain can be obtained. In addition, by using a homopolymer or a copolymer obtained by polymerizing a polyamide, particularly a monomer represented by the general formula (II), in the intermediate layer, stable potential characteristics are exhibited for a very long time. Therefore, a good image without an abnormal image can be obtained.

Claims (3)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive support and a photosensitive layer having function separation for charge generation and charge transfer, and an intermediate layer and a protective layer, wherein the protective layer is a phosphazene curable resin. An electrophotographic photosensitive member characterized by comprising conductive fine particles dispersed therein. 2. The electrophotographic photosensitive member according to claim 1, wherein the intermediate layer is made of polyamide. 3. The electrophotographic photosensitive member according to claim 1, wherein the intermediate layer is made of an acrylic anilide resin.