JP3482485B2 - Electrophotographic photoreceptor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in electrophotographic copying machines, printers, facsimiles and the like.

[0002]

2. Description of the Related Art In recent years, electrophotographic copying machines and laser printers and facsimiles to which electrophotographic technology is applied have been remarkably widespread, and their range of use is expanding as the size and cost of these devices are reduced. As the range of use expands, the operating environment of the equipment is expanding from the conventional business offices to supermarkets, privately run shops, general households and the like. On the other hand, a so-called organic photoconductor (OPC photoconductor) using an organic photoconductive substance has been put into practical use as a photoconductor mounted on an electrophotographic copying machine, a printer, or the like. In an electrophotographic photoconductor, generally, ions generated by corona discharge are scattered on the photoconductor surface to charge the photoconductor surface. In this method, ozone and NOx are inevitably produced from oxygen and nitrogen in the air during corona discharge. Further, when an oil stove or a gas stove is used for heating in the winter, etc., a considerably large amount of NOx is generated from these heating devices. Therefore, the copier,
It can be said that printers, facsimiles, etc. are exposed to an atmosphere containing at least a small amount of ozone and NOx.

OPC photoconductors are highly productive and inexpensive, but electrophotographic characteristics such as decrease in charging potential, sensitivity fluctuation and increase in residual potential are likely to occur due to oxidizing gas such as ozone and acid gas such as NOx. . Therefore, it has been conventionally known to add an antioxidant to the OPC photosensitive member in order to prevent the deterioration. For example, JP-A-61-160552
In the publication, the charge transport layer contains 2,6-di-t-butyl-p.
-A method of adding an antioxidant such as cresol (abbreviated as BHT), and JP-A-62-265666 discloses that a specific dihydric phenol, a specific aminophenol and a specific diphenylamine compound are contained in a charge transport layer. A method of adding at least one antioxidant selected from
Japanese Unexamined Patent Publication No. 3-18356 discloses a method of adding an antioxidant such as hindered phenols or paraphenylenediamines to the charge generation layer. However, since it is difficult to remove acid gas sufficiently by the conventional technique, the OP
C It is not possible to sufficiently prevent the electrophotographic characteristic deterioration of the photoconductor.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photosensitive member whose chargeability is not significantly reduced even when exposed to an acidic gas such as NOx.

That is, according to the present invention, the following inventions are provided.
To be done. (1) At least on a conductive supportCharge generation layer and charge
Transport layers were sequentially stackedFor electrophotographic photoreceptors with a photosensitive layer
Be carefulThe charge generation layer contains at least an azo pigmentAnd
On the photosensitive layerNeutral or basic α-Contains amino acid compounds
An electrophotographic photoconductor characterized by the following. (2)At least the charge-generating substance and the
Electrophotography having a photosensitive layer containing a load-transporting substance
In the photoconductor, at least the charge generation layer contains an azo pigment.
And neutral or salt in the intermediate layer or the intermediate layer and the charge generation layer.
A battery characterized by containing a basic α-amino acid compound
Child photoconductor. (3)Neutral or basic α-amino acid compoundArgini
, Asparagine, glutamine, histidine and those
Be one selected from the derivatives ofCharacterizing
In (1) or (2)The electrophotographic photosensitive member described.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The amino acid compound used in the present invention is a compound having a carboxyl group and an amino group in the molecule. The compounds include aliphatic monoaminomonocarboxylic acids such as glycine, alanine, valine, leucine and isoleucine; aliphatic oxyamino acids such as serine and threonine; aliphatic monoaminodicarboxylic acids such as aspartic acid and glutamic acid; lysine and arginine. Isoaliphatic diaminomonocarboxylic acids; sulfur-containing amino acids such as cystine, cystine and methionine; aromatic amino acids such as phenylalanine and tyrosine; histidine, tryptophan,
Amino acids having a heterocycle such as proline and oxyproline; amino acid amides such as asparagine and glutamine; and the like.

In the present invention, it is preferable to add the amino acid compound or its derivative to the photosensitive layer of the electrophotographic photosensitive member. The amino acid compound has an acidic group such as a carboxyl group and a basic group such as an amino group, and the pH of the aqueous solution differs depending on the ratio of the two contained in the molecule, but the amino acid compound preferably used in the present invention is neutral. Α- in the basic region
It is an amino acid compound. Amino acid compounds preferably used in the present invention include arginine; arginine derivatives such as N-nitroarginine, N-methylarginine, N-nitroarginine methyl ester; asparagine, glutamine, histidine, lysine, tryptophan, phenylalanine, tyrosine. Derivatives thereof; and the like.

The mechanism by which the charge potential of the photoconductor is lowered by an acidic gas such as NOx is not well understood, but basically, the acidic gas enters the photosensitive layer formed of the charge generating substance and the charge transporting substance, and the charge generating substance is generated. Acid charge acts on the contact interface between the charge transport material and the charge transport material or the charge transport material to form a free charge carrier that easily moves in a low electric field in the photosensitive layer, or charge from a layer adjacent to the layer. It is presumed that the carrier is easily injected. The amino acid compound used in the present invention prevents the generation of the charge carriers by trapping an acidic gas, so that the compound is preferably added to the photosensitive layer and / or a layer adjacent to the photosensitive layer. The adjacent layers include an intermediate layer provided between the photosensitive layer and the conductive support and a protective layer provided on the photosensitive layer. The intermediate layer is provided for the purpose of increasing the chargeability of the photoconductor or preventing the occurrence of spot-like abnormal images due to local charge leakage, preventing the occurrence of moire-like abnormal images when a laser is used as the writing light source, The protective layer is provided for the purpose of preventing abrasion and damage of the photosensitive layer.

As described above, in the present invention, the amino acid compound is added to the photosensitive layer and / or the layer adjacent to the photosensitive layer. When it is added to the photosensitive layer, it is preferably added to the charge generation layer as a function separation type described later. Further, when the amino acid compound is added to the intermediate layer, it is possible to suppress the decrease in the sensitivity of the photoconductor and to reduce the decrease in the charging property due to the oxidizing gas such as NOx. The amount of the amino acid compound added is 0.1 to 100%, preferably 0.1 to 100% by weight of the charge generating substance in the layer when the amino acid compound is added to the dispersion type photosensitive layer described later.
It is ˜50%, and is 0.1 to 100%, preferably 0.1 to 50% of the weight of the charge generating substance in the layer when the function-separated photosensitive layer is added to the charge generating layer. When added to the charge transport layer, 0.1 to 100% by weight of the charge transport material in the layer,
It is preferably 0.1 to 50%, and when added to the layer adjacent to the charge generation layer or the dispersion type photosensitive layer of the function separation type photosensitive layer,
0.1 to 100%, preferably 0.1 to 100% by weight of the adjacent layer
50%. The same or different amino acid compound may be added to both the photosensitive layer and the layer adjacent to the photosensitive layer.

The photosensitive layer of the electrophotographic photosensitive member only needs to have both the charge generating substance and the charge transporting substance, and both of them can be present in the photosensitive layer as a dispersion type or a function separation type. The former is formed by providing a photosensitive layer in which a charge generating substance and a charge transporting substance are dispersed in a binder resin on a conductive support. The latter is formed by providing a charge generating layer containing a charge generating substance and a binder resin on a conductive support, and laminating a charge transporting layer containing a charge transporting substance and a binder resin on it (hereinafter,
This structure may be referred to as a normal layer structure), or the charge generation layer and the charge transport layer may be laminated in reverse (hereinafter, this structure is referred to as a reverse layer structure). And, when the photoreceptor of the reverse layer constitution is used, the charging polarity is opposite to that when the photoreceptor of the forward layer constitution type is used, and when the charge transport layer has a hole transporting property, it is usually negatively charged and reversely charged in the photoreceptor of the forward layer constitution. It is used for positive charging in the layer-structured photoreceptor, and is reversed when the charge transport layer is electron transportable. Further, in the case of the function-separated type, a charge-transporting substance may be contained in the charge-generating layer, and the sensitivity can be enhanced by this method in the case of the reverse layer structure. In addition, an intermediate layer may be provided between the photosensitive layer and the conductive support in order to improve the adhesiveness and the charge blocking property, and the upper surface of the photosensitive layer may be improved in order to improve abrasion resistance and mechanical durability. You may provide a protective layer.

The charge generating substance used in the electrophotographic photoreceptor of the present invention may be an inorganic substance or an organic substance as long as it absorbs light to generate a charge carrier. For example, amorphous selenium,
Inorganic substances such as trigonal selenium, selenium-arsenic alloy, selenium-tellurium alloy, cadmium sulfide, zinc oxide, and amorphous silicon are used. Organic substances include phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine; azurenium salt pigments; squaric acid methine pigments; carbazole skeleton, triphenylamine skeleton, diphenylamine skeleton, dibenzothiophene skeleton, oxadiazole skeleton, fluorenone skeleton, bis Azo pigments having a stilbene skeleton, a distyryl oxadiazole skeleton and a distyryl carbazole skeleton; a perylene pigment; an anthraquinone pigment or a polycyclic quinone pigment; a quinone imine pigment; a diphenylmethane or triphenylmethane pigment; a benzoquinone and a naphthoquinone pigment; Cyanine and azomethine pigments; indigoid pigments; bisbenzimidazole pigments and the like are used. These charge generating substances can be used alone or in combination of two or more.

The charge transport material used in the present invention includes:
Both hole transporting substances and electron transporting substances can be used, and all known charge transporting substances can be used. And, as the electron transport material, chloranil, bromanil, tetracyanoethylene, tetracyanoquinone dimethane, 2,
4,7-trinitro-9-fluorenone, 2,4,5,
7-tetranitro-9-fluorenone, 2,4,5,7
-Tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno (1,2-b) thiophen-4-one, 1,3,7-
Examples thereof include electron-accepting substances such as trinitrodibenzothiophene-5,5-dioxide. Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives; poly-γ-carbazolylethylene glutamate and its derivatives; pyrene-formaldehyde condensate and its derivatives; polyvinylpyrene; polyvinylphenanthrene; oxazole derivatives; oxadi Azole derivatives; imidazole derivatives; mono-, di- and triarylamine derivatives;
Examples of known materials include stilbene derivatives; α-phenylstilbene derivatives; benzidine derivatives; diaryl and triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, and butadiene derivatives. These charge transport substances can be used alone or in combination of two or more.

The binder resin used for forming the charge generation layer, the charge transport layer and the dispersion type photosensitive layer may be any known binder resin for an electrophotographic photoreceptor having good insulating property, and is not limited. That is, bisphenol A type or bisphenol Z type polycarbonate, polyester, methacrylic resin, acrylic resin, polyethylene, polyvinyl chloride, polyvinyl acetate, polystyrene, phenol resin,
Epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyarylate, polyacrylamide, polyamide, phenoxy resin and the like are used. These binder resins can be used alone or as a mixture of two or more kinds.

When a photoconductor is manufactured by using the above layer structure and materials, the thickness and composition of each layer have a preferable range. For example, in the case of the normal layer constitution type (lamination of conductive support / charge generation layer / charge transport layer), the ratio of the charge generation substance to the binder resin is 20% by weight or more and the layer thickness is 0.01 in the charge generation layer. It is preferably set to ˜5 μm. In the charge transport layer, the ratio of the charge transport material to the binder resin is 20 to 20.
It is preferably 0% by weight and the layer thickness is 5 to 100 μm.
In the charge transport layer in the case of the reverse layer constitution type (conductive support / charge transport layer / charge generation layer lamination), the ratio of the charge transport material to the binder resin is 20 to 200% by weight, and the layer thickness is 5 The charge generation layer preferably contains 20% by weight or more of the binder resin. In addition, it is preferable to include a charge transporting substance in the charge generation layer, and when it is included, the residual potential is suppressed and the sensitivity is improved. In this case, the charge transport substance is preferably contained in the binder resin in an amount of 20 to 200% by weight. In the case of a dispersion type photoreceptor, the charge generating substance is added in an amount of 5 to 95% by weight to the binder resin in the photosensitive layer, and the layer thickness is 1
The thickness is preferably 0 to 100 μm. In that case, the ratio of the charge transport material to the binder resin is preferably 30 to 200% by weight.

The conductive support used in the present invention is a support having a volume resistance of 10 ¹⁰ Ω · cm or less, and a resin film coated with a conductive material such as a metal plate or metal is used. be able to. And, as the conductive material, aluminum, nickel, chromium, nichrome, copper, silver,
Metals such as gold and platinum; metal oxides such as indium oxide and tin oxide; carbon black; copper iodide;
The conductive support is a plate of the conductive metal, or DI, I
It can be manufactured by subjecting a metal tube formed by a method such as I, extrusion or drawing to surface treatment by a method such as polishing after cutting and superfinishing. The preferred metal materials for this method are aluminum, aluminum alloys, nickel, stainless steel and the like. Further, paper or resin may be formed into a film shape, a cylindrical drum shape, a belt shape or the like, and the conductive material may be coated thereon by a method such as vapor deposition or sputtering. Furthermore, conductive powder such as carbon black, indium oxide, tin oxide, etc. is well dispersed in the binder resin,
This can be manufactured by coating it on a resin or the like.

Next, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 0.20 g of a trisazo compound represented by the following formula (1)
And 2 wt% polyvinyl butyral resin (UCC:
XYHL) -cyclohexanone solution 4.0 g and N-nitro-L-arginine (manufactured by Aldrich) 0.02 g
Was charged into a glass container having an inner volume of 50 cm ³ containing 100 g of PSZ-balls having a diameter of 5 mm, ball milling was performed for 5 days, 14 g of cyclohexanone was added, and ball milling was further performed for 1 day to prepare a coating solution for forming a charge generation layer. did.

[Chemical 1] An aluminum vapor-deposited polyethylene terephthalate film having a thickness of 75 μm was used as a conductive support, and the coating solution for forming a charge generating layer was coated on the conductive support by a blade, and then at 3 ° C. at 3 ° C.
It was heated and dried for a minute to form a charge generation layer having a thickness of about 0.2 μm on the conductive support. Next, a coating solution for forming a charge transport layer having the following composition was prepared, and the coating solution was blade-coated on the conductive support on which the charge generation layer was formed.
After heating and drying at 0 ° C. for 3 minutes, the drying temperature was raised to 130 ° C. and further drying for 5 minutes to form a charge transporting layer having a thickness of about 22 μm on the charge generating layer to prepare a photoconductor of Example 1. Polycarbonate resin (C-1400 manufactured by Teijin Chemicals Ltd.) 10 g α-phenylstilbene compound represented by the following formula (2) 8 g Dichloromethane 102 g

[Chemical 2]

Example 2 L-arginine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used in place of N-nitro-L-arginine as the amino acid compound added to the coating liquid for forming the charge generation layer, and otherwise the same as in Example 1. Similarly, a photoconductor of Example 2 was prepared.

Example 3 The amino acid compound to be added to the coating liquid for forming the charge generation layer was D
Example 1 except that L-arginine (manufactured by Tokyo Kasei) was used.
A photoconductor of Example 3 was manufactured in the same manner as in.

Comparative Example 1 An amino acid compound was not added to the charge generation layer forming coating solution,
A photoreceptor of Comparative Example 1 was produced in the same manner as in Example 1 except for the above.

Comparative Example 2 2,6-di-t-butyl-p-cresol (BHT) was added in place of N-nitro-L-arginine to the coating liquid for forming the charge generation layer, and the other examples were used. A photoconductor of Comparative Example 2 was prepared in the same manner as in 1.

Example 4 D-asparagine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used in place of N-nitro-L-arginine as the amino acid compound added to the coating liquid for forming the charge generation layer, and otherwise the same as in Example 1. Similarly, a photoconductor of Example 4 was produced.

Examples 5 to 10 Table 1 shows the amino compounds added to the coating liquid for forming the charge generation layer.
Photosensitive members of Examples 5 to 10 were produced in the same manner as in Example 1 except that the ones described in 1 were replaced.

[0024]

[Table 1]

Example 11 [Intermediate layer coating component] A solution of polyvinyl butyral resin (XYHL manufactured by UCC) in cyclohexanone (4% by weight) 4 g D-asparagine 0.10 g The above coating components together with 100 g of a 5 mmφ PSZ ball. The mixture was placed in a 50 cc glass container, milled for 5 days, added with 5 g of cyclohexanone, and milled for another day to prepare an intermediate layer coating solution. The above-mentioned coating solution for the intermediate layer was applied onto aluminum of the aluminum vapor-deposited polyester film, and then dried by heating at 80 ° C. for 3 minutes to form an intermediate layer having a thickness of about 0.5 μm. A photoconductor of Example 11 was prepared by stacking the same charge generation layer and charge transport layer as in Example 4 on the intermediate layer except that the amino acid was not added to the charge generation layer forming coating solution.

Comparative Example 3 A photoconductor of Comparative Example 3 was prepared in the same manner as in Example 11 except that D-asparagine was not added to the intermediate layer.

[0027]

[Evaluation of Photoreceptors of Examples and Comparative Examples] Using an electrostatic characteristic measuring device EPA-8100 manufactured by Kawaguchi Electric Co., Ltd.
11 and the photoconductors of Comparative Examples 1 to 4 were evaluated. That is,
The charging potential V ₂ when charged for 2 seconds at a voltage of −5.5 Kv was measured, and the photoconductor was charged so that the surface potential became 800 V. Then, the light from a 2856 K tungsten lamp was set to 4.5. It is irradiated so that it looks good, and the surface potential is changed from 800 V to 400 by light irradiation.
The photoconductor sensitivity was determined from the amount of light required to attenuate to volts. Next, the photoreceptor was exposed to air containing ₂₀ ppm of NO and 5 ppm of NO ₂ for 24 hours, and then the charging characteristics and the sensitivity were measured again to examine the state of deterioration of the photoreceptor due to NOx. The results are shown in Table 2. In the table, E1 / 2 represents the amount of light (lux seconds) required for the surface potential to be attenuated from 800 V to 400 V.

[0028]

[Table 2] (-): Cannot be measured because it was not charged to -800 volts

It can be seen from Table 2 that the photoconductors of the examples have almost no deterioration in chargeability even if they are left in an atmosphere containing NOx gas, whereas the photoconductors of the comparative examples are exposed to NOx gas in an atmosphere containing NOx gas. It can be seen that the charging property is significantly reduced. Further, it can be seen that the sensitivity of the photoconductors of the examples does not decrease so much even if they are left in an atmosphere containing NOx gas.

[0030]

EFFECT OF THE INVENTION The electrophotographic photoreceptor of the present invention is less susceptible to deterioration in chargeability in an atmosphere containing an oxidizing gas such as NOx, and therefore is less likely to deteriorate even after long-term use. Is. Therefore, it can be said that the electrophotographic photosensitive member has high productivity and can be manufactured at a low price and has a long life. Particularly, the photoconductor containing the amino acid compound in the intermediate layer can suppress the decrease in the sensitivity of the photoconductor, and
It is possible to reduce a decrease in chargeability due to an oxidizing gas such as Ox.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-62-184468 (JP, A) JP-A-61-35452 (JP, A) JP-A-7-191477 (JP, A) JP-A-6- 265241 (JP, A) JP-A-5-72786 (JP, A) JP-A-1-178970 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 5/00

Claims (3)

(57) [Claims] 1. At least charge generation on a conductive support.
In an electrophotographic photoreceptor having a photosensitive layer in which a charge transport layer and a charge transport layer are sequentially stacked , the charge generation layer contains at least an azo pigment.
An electrophotographic photosensitive member having a photosensitive layer and containing a neutral or basic α- amino acid compound. 2. At least charge generation on a conductive support.
A photosensitive layer containing a substance and a charge transport substance is formed
In the electrophotographic photoreceptor, at least the charge generation layer is azo.
Contains a pigment, and the intermediate layer or intermediate layer and charge generation layer
Characterized by containing a basic or basic α-amino acid compound
And an electrophotographic photoreceptor. 3. The neutral or basic α-amino acid compound is one selected from arginine, asparagine, glutamine, histidine and derivatives thereof .
The electrophotographic photosensitive member according to claim 1 or 2 .