JP2961818B2 - Photoconductor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoreceptor containing a pyrazoline-based fluorescent whitening agent as an additive.

[Prior art and problems] Generally, in electrophotography, the surface of a photosensitive layer of a photoreceptor is charged and exposed to form an electrostatic latent image, which is developed with a developer, visualized, and the visible image is formed. A direct method in which a copy image is obtained by fixing directly on the photoreceptor as it is, or a powder image transfer method in which the visible image on the photoreceptor is transferred onto a transfer material such as paper and the transferred image is fixed to obtain a copy image Alternatively, there is known a latent image transfer method in which an electrostatic latent image on a photosensitive member is transferred onto transfer paper, and the electrostatic latent image on the transfer paper is developed and fixed.

As a material constituting a photosensitive layer of a photoreceptor used in this type of electrophotography, conventionally, selenium, gadmium sulfide,
Inorganic photoconductive materials such as zinc oxide are known.

While these photoconductive materials have many advantages, for example, less charge dissipation in a dark place, or the ability to quickly dissipate charge by light irradiation, they have various disadvantages. For example, in the case of a selenium-based photoconductor, manufacturing conditions are difficult, the manufacturing cost is high, and the selenium-based photoconductor is susceptible to heat and mechanical shock.
Cadmium sulfide photoreceptors and zinc oxide photoreceptors do not provide stable sensitivity in humid environments, and dyes added as sensitizers cause charge deterioration due to corona charging and photobleaching due to exposure, resulting in long-term However, there is a disadvantage that stable characteristics cannot be provided over a wide range.

On the other hand, various organic photoconductive polymers such as polyvinyl carbazole have been proposed, but these polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film-forming properties and lightness. However, they are still inferior to inorganic photoconductive materials in terms of sufficient sensitivity, durability and stability due to environmental changes.

The low molecular weight organic photoconductive compound is preferable in that the physical properties of the film or the electrophotographic properties can be controlled by selecting the type and composition ratio of the binder used in combination. Since it is used together with the material, high compatibility with the binder is required.

A photoreceptor in which these high molecular weight and low molecular weight organic photoconductive compounds are dispersed in a binder resin has drawbacks such as a large residual potential due to many carrier traps and low sensitivity. Therefore, it has been proposed to solve the above-mentioned drawbacks by blending a charge transport material with a photoconductive compound.

Also, a function-separated type photoreceptor has been proposed in which the charge generation function and the charge transport function of the photoconductive function are shared by different substances. In such a function-separated type photoreceptor, many organic compounds are mentioned as the charge transporting material used for the charge transporting layer, but there are various problems in practice. For example, 2,5-bis (P-diethylaminophenyl) 1,3,4-oxadiazole described in U.S. Pat. No. 3,189,447 has low compatibility with a binder and tends to precipitate crystals. U.S. Patent 3,820,989
Although the diarylalkane derivative described in JP-A No. 2000-214,1992 has good compatibility with a binder, the sensitivity changes when repeatedly used. The hydrazone compounds described in JP-A-54-59143 have relatively good residual potential characteristics, but have the drawback of inferior chargeability and repetition characteristics.

Thus, in order to satisfy the practicality as a photoreceptor, it is necessary to be excellent in repetition characteristics, light fatigue characteristics, their durability, etc. in addition to sensitivity and charging ability.

However, the organic photoreceptor generally has a problem in that the initial surface potential or light attenuation characteristics are not constant due to repeated use, and there is a problem that light fatigue is severe and durability is poor.

Techniques for improving the photosensitivity and durability of the photoreceptor include, for example, JP-A-60-191264 and JP-A-59-12.
No. 3845 is known.

JP-A-60-191264 discloses a technique capable of achieving excellent photosensitivity and repetition characteristics of initial surface potential by including a hydrazone compound in a photosensitive layer. This technique discloses that the addition of an acridine dye, a thiazine dye or an oxazine dye is effective for further sensitizing the light sensitivity. However, the photoreceptor still has a disadvantage that when repeatedly used, electrophotographic characteristics such as surface potential and residual potential are not stable.

JP-A-59-123845 discloses an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated by adding an electron donating substance such as phenazine and triazole to the charge generation layer. Discloses a technique for improving the injection efficiency of carriers generated in the charge generation layer into the charge transport layer and improving the photosensitivity characteristics. It is not intended to improve.

Japanese Patent Application Laid-Open No. 62-249167 discloses that a thioxanthone-based compound is added to a photosensitive layer to stabilize repetition characteristics, and Japanese Patent Application Laid-Open No. 62-262053 discloses that a thiuram monosulfide-based compound is added to a photosensitive layer. Stabilizing the repetition properties by adding a compound; and
No. 6 discloses stabilizing the repetition characteristics by adding a triphenylmethane dye.

Furthermore, a photosensitive member containing an antioxidant in the photosensitive layer (JP-A-57-122444) and a photosensitive member containing an ultraviolet absorber in the uppermost layer of the photosensitive layer (JP-A-57-132154) ), A photoreceptor containing a benzophenone-based compound in the charge transport layer (JP-A-58-163945), or a photoreceptor in which a cyanovinyl-based electron-accepting substance is added to the charge-transport layer (JP-A-58-7643) Japanese Patent Application Laid-Open Publication No. H11-64131 discloses a photosensitive member to which various additives are added.

However, in any of the above-mentioned photoreceptors, further improvement in the photoreceptor characteristics such as repetition characteristics and durability is desired, and the type of the additive differs from the additive disclosed in the present application.

[Problems to be solved by the invention]

The present invention has been made in view of the above circumstances, and has initial characteristics (sensitivity, surface potential, etc.) even when used repeatedly.
It is an object of the present invention to provide a photoreceptor which can maintain a stable image quality and can form a stable copy image with little deterioration.

This object is achieved by adding a pyrazoline-based fluorescent whitening agent to the photosensitive layer.

[Means for solving the problem]

That is, the present invention comprises a single-layer photosensitive layer containing a charge generating substance, a charge transporting substance and a pyrazoline-based fluorescent whitening agent, or a charge transporting substance and a pyrazoline-based fluorescent whitening agent on a conductive support. A photoreceptor having a laminated photosensitive layer in which a charge transport layer and a charge generation layer containing a charge generation substance are laminated, wherein the pyrazoline-based fluorescent whitening agent has the following general formula [1]; [Wherein, R ₁ represents a hydrogen atom, a lower alkyl group, or a halogen atom, and R ₂ represents a lower alkyl group, a —SO ₃ Na group, a —SO ₂
It represents an NH ₂ group or a —COOCH ₃ group, and R ₃ represents a hydrogen atom or an aryl group. Provided that R ₃ is an aryl group and R ₂ is a lower alkyl group].

As described above, by adding the pyrazoline-based fluorescent whitening agent to the photosensitive layer containing the charge transporting substance, it is possible to obtain a high-performance photoreceptor with little change in initial characteristics even when used repeatedly.

In the present invention, pyrazoline-based fluorescent whitening agents are various derivatives having pyrazoline as a basic skeleton, meaning that they are used as fluorescent whitening agents. The substance fluoresces in sunlight,
Substances that have the effect of increasing whiteness when viewed with the eye,
More specifically, it is one that emits light in the ultraviolet region at a wavelength of about 420 nm and emits blue light, and has the following general formula [I]; [In the formula, R ₁ represents a hydrogen, a lower alkyl group such as a methyl group or a halogen atom such as a chlorine atom; R ₂ represents a lower alkyl group such as a methyl group, a —SO ₃ Na group, a —SO ₂ NH ₂ group or It represents a -COOCH _3; R ₃ may be mentioned compounds represented by the representative] an aryl group such as a hydrogen atom or a phenyl group.

Specifically, compounds represented by the following structural formulas can be exemplified.

The photoreceptor of the present invention has a photosensitive layer containing one or more pyrazoline-based fluorescent whitening agents.

Although various forms of photoreceptors are known, the pyrazoline-based fluorescent whitening agent may be contained in the photosensitive layer of any of the photoreceptors.

For example, a single-layer photoreceptor having a charge generating material and a photosensitive layer formed by dispersing a charge generating material in a resin binder on a support, or a charge generating layer having a charge generating material as a main component is provided on a support. And a so-called laminated photoreceptor provided with a charge transport layer thereon.

To produce a single-layer photoreceptor, together with a pyrazoline-based fluorescent whitening agent, fine particles of a charge generating material are dispersed in a resin solution and a solution in which a charge transport material and a resin are dissolved,
This may be applied on a conductive support and dried.

At this time, the charge transporting material is generally used in an amount of 0.01 to 2 parts by weight with respect to 1 part by weight of the binder resin.
0.1 to 40% by weight, preferably 0.5 to 30% by weight, more preferably 1 to 20% by weight. If the content is more than 40% by weight, the sensitivity is deteriorated and the residual potential is increased. If the amount is less than 0.1% by weight, the effect of the present invention cannot be sufficiently obtained.

The thickness of the photosensitive layer is 3 to 30 μm, preferably 5 to 20 μm. If the amount of the charge generating material used is too small, the sensitivity is poor, and if it is too large, the chargeability is deteriorated, the mechanical strength of the photosensitive layer is reduced, and the proportion in the photosensitive layer is 1 part by weight of the resin. 0.01 to 3 parts by weight, preferably 0.2 to 2 parts by weight
The range of parts by weight is good.

To produce a laminated photoreceptor, a charge generation material is vacuum-deposited on a conductive support, or dissolved in a solvent such as an amine and applied, or a pigment is applied to a suitable solvent or a binder if necessary. A coating solution prepared by dispersing in a solution in which a resin is dissolved is applied and dried, and then a solution containing a pyrazoline-based fluorescent whitening agent, a charge transport material and a binder is applied and dried.

When the charge generation layer is formed of a binder resin dispersion type, the charge generation material is used in an amount of 0.1 to 5 parts by weight with respect to 1 part by weight of the binder resin for the same reason as the case of forming the single layer type photosensitive layer.

In the charge transporting layer, the proportion of the charge transporting material in the layer is 0.2 to 2 parts by weight, preferably 0.3 to 1.3 parts by weight based on 1 part by weight of the binder resin, and the amount of the pyrazoline-based fluorescent whitening agent added. Is 0.1 to 40% by weight, preferably 0.5 to 30% by weight, more preferably 1 to 20% by weight, based on the charge transporting material, for the same reason as described for the single-layer type photosensitive layer.
% By weight.

The thickness of the charge generation layer is 4 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer is 3 to 30 μm, preferably 5 to 20 μm.

In the present invention, as the electrically insulating binder resin used for forming the photosensitive layer, a thermoplastic resin or a thermosetting resin, a photocurable resin, a photoconductive resin, or the like, which is known per se, is an electrically insulating resin. An adhesive can be used.

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins,
Thermoplastic resins such as acrylic resin, ethylene-vinyl acetate resin, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, and styrene resin ; Epoxy resin, urethane resin, silicone resin, phenol resin,
Thermosetting resins such as melamine resins, xylene resins, alkyd resins, and thermosetting acrylic resins; photocurable resins; photoconductive resins such as polyvinylcarbazole, polyvinylpyrene, polyvinylanthracene, and polyvinylpyrrole.

These can be used alone or in combination.

These electrically insulative resins were measured alone to be 1 × 10 ¹² Ω
-It is desirable to have a volume resistance of not less than cm.

Examples of the charge generation material used for forming the photosensitive layer include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, cyanine dyes, styryl dyes, pyrylium dyes, and azo pigments. , Organic substances such as quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarium salt pigments, azulene pigments, phthalocyanine pigments, and selenium, Selenium alloys such as selenium / tellurium, selenium / arsenic, cadmium sulfide, cadmium selenide, zinc oxide,
An inorganic substance such as amorphous silicon can be used. In addition, any material that absorbs light and generates charge carriers at an extremely high probability can be used.

Examples of those applicable to vacuum deposition include phthalocyanines such as metal-free phthalocyanine, titanyl phthalocyanine, and aluminum chlorophthalocyanine.

Examples of the charge transport material used for forming the photosensitive layer include hydrazone compounds, styryl compounds, triphenylmethane compounds, oxazoles, oxadiazole compounds, carbazole compounds, stilbene compounds, enamine compounds, oxazole compounds, triphenylamine compounds, and tetraphenylbenzidine. Various compounds such as a compound and an azine compound can be used, and examples thereof include carbazole, N-ethylcarbazole, N-vinylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2 , 3−
Benzochrysene, 3,4-benzopyrene, fluorene, 1,2
-Benzofluorene, 4- (2-fluorenylazo) resorcinol, 2-p-anisoleaminofluorene,
p-diethylaminoazobenzene, cadion, N, N-dimethyl-p-phenylazoaniline, p- (dimethylamino) stilbene, 9- (4-diethylaminostyryl) anthracene, 2,5-bis (4-diethylaminophenyl) 1, 3,5-oxadiazole, 1-phenyl-3
-(P-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3-phenyl-5-pyrazolone, 2- (p-diethylaminostyryl) -6-diethylaminobenzoxazole, 2
-(P-diethylaminostyryl) -6-diethylaminobenzothiazole, bis (4-diethylamino-2-
Methylphenyl) phenylmethane, 1,1-bis (4-N, N
-Diethylamino-2-ethylphenyl) heptane, N,
N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, N, N-diphenylhydrazino-3-
Methylidene-10-ethylphenothiazine, 1,1,2,2, tetrakis- (4-N, N-diethylamino-2-ethylphenyl) ethane, p-diethylaminobenzaldehyde-
N, N-diphenylhydrazone, p-diphenylaminobenzaldehyde-N, N-diphenylhydrazone, N-ethylcarbazole-N-methyl-N-phenylhydrnisone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone , P-diethylaminobenzaldehyde-3-methylbenzthiazolinone-2
-Hydrazone, 2-methyl-4-N, N-diphenylamino-β-phenylstilbene, α-phenyl-4-N, N
-Diphenylaminostilbene, 1,1-bis- (p-
Diethylaminophenyl) -4,4-diphenyl-1,3-butadiene and the like.

These transport substances are used alone or in combination of two or more.

The photoreceptor of the present invention further comprises a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutylphthalate, O-terphenyl, chloranil, tetracyanoethylene, 2,4,7 together with a binder resin.
Electron-withdrawing sensitizers such as trinitrofluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-dinitrobenzoic acid,
Sensitizers such as methyl violet, rhodamine B, cyanine dyes and pyrylium salts may also be used.

Further, an antioxidant, an ultraviolet absorber, a dispersing aid, an anti-settling agent, and the like may be appropriately used.

As the conductive support used in the photoreceptor of the present invention,
Copper or aluminum, silver, iron, zinc, nickel or other metal or alloy foils or plates in the form of sheets or drums are used, or these metals are vacuum-deposited or electrolessly plated on plastic films or the like. Or a material in which a layer of a conductive compound such as a conductive polymer, indium oxide or tin oxide is provided on a support such as paper or a plastic film by coating or vapor deposition.

In addition, any of the photoreceptors obtained as described above may be provided with an adhesive layer or a barrier layer and a surface protective layer as necessary.

As a material used for the intermediate layer, polyimide, polyamide, nitrocellulose, polyvinyl butyral, a polymer such as polyvinyl alcohol as it is, or a dispersion of a low-resistance compound such as tin oxide or indium oxide, aluminum oxide, zinc oxide, A deposited film of silicon oxide or the like is suitable.

 The thickness of the intermediate layer is desirably 1 μm or less.

As the material used for the surface protective layer, a polymer such as an acrylic resin, a polyaryl resin, a polycarbonate resin, or a urethane resin as it is, or a material in which a low-resistance compound such as tin oxide or indium oxide is dispersed is suitable.

An organic plasma polymerized film can also be used. The organic plasma polymerized film is appropriately oxygen, nitrogen, halogen,
It may contain atoms of the third and fifth groups of the periodic table.

 The thickness of the surface protective layer is desirably 5 μm or less.

The photoreceptor of the present invention can be used for a photoreceptor for a laser printer.

Example 1 Bisazo compound represented by the following chemical formula [A]: One part of butyral resin (BH-3: manufactured by Sekisui Chemical Co., Ltd.) was dispersed in a sand mill together with 90 parts of cyclohexanone. The obtained dispersion liquid of the bisazo compound was applied on an aluminum drum so that the film thickness after application was 0.2 g / m ^2, and then dried.

A distyryl compound represented by the following chemical formula [B] is formed on the thus obtained charge generation layer: 10 parts, 10 parts of a polycarbonate resin (PC-Z: manufactured by Mitsubishi Gas Chemical Co., Ltd.) were dissolved in 80 parts of tetrahydrofuran, and a coating solution containing 0.3 part of a pyrazoline compound [4] added was applied by a dipping method. A 20 μm charge transport layer was formed.

Thus, a photoreceptor having a two-layered photosensitive layer was obtained.

Comparative Example 1 A photoconductor was prepared by the same way as that of Example 1 except that compound [4] was not added.

Example 2 4.5 parts of α-type titanyl phthalocyanine, 4.5 parts of butyral resin (BX-1: manufactured by Sekisui Chemical Co., Ltd.) and 0.45 part of a pyrazoline compound [5] were dispersed together with 500 parts of dichloroethane in a sand mill. The resulting dispersion was coated on an aluminum drum so that the coating liquid had a thickness of 0.2 g / m ^2, and then dried.

A butadiene compound represented by the chemical formula [C] is formed on the charge generation layer thus obtained: A hydrazone compound represented by 10 parts and a chemical formula [D]: 40 parts and polyarylate (U-100: manufactured by Unitika)
A solution prepared by dissolving 50 parts in 500 parts of tetrahydrofuran was applied and dried to form a charge transport layer having a thickness of about 15 μm.

Thus, a photoreceptor having a two-layered photosensitive layer was obtained.

Examples 3 to 6 In Example 2, the addition amount of the compound [5] was 0.23 parts, 0.68
A photoreceptor was prepared in the same manner as in Example 2, except that the parts were changed to 0.9 part, 0.9 part and 1.35 part.

Comparative Example 3 A photoconductor was prepared by the same way as that of Example 2 except that Compound [5] was not added.

Comparative Example 4 A photoconductor was prepared by the same way as that of Example 2 except that 0.45 part of trinitrofluorenone was added instead of compound [5].

Comparative Example 5 In Example 2, 1H-1,2,4 was used instead of compound [5].
A photoconductor was prepared by the same way as that of Example 2 except that 0.45 part of triazole was added.

Evaluation The photoreceptor obtained in this way was converted to a commercially available electrophotographic copying machine (EP
−50 (50φ: manufactured by Minolta Camera Co.), and corona charged at −6 KV, and the initial surface potential V.

(V), exposure amount E required to reduce the initial potential to 1/2
The decay rate DDR ₁ (%) of the initial potential when left in the dark for _1/2 (lux · sec) for 1 second was measured. Table 1 shows the results.

Further, the photoreceptor was attached to a photoreceptor tester (FIG. 1) having the same configuration as the copying machine, and the electrophotographic characteristics were measured.

That is, the photoconductors obtained in Examples and Comparative Examples were mounted on the photoconductor drum (1), charged to −500 V by the charger (2), and then 0.3 seconds later, the initial surface potential (V) of the photoconductor, After charging, the surface potential (V ₁ ) after exposure to white light (3) from a halogen lamp and the residual potential (V _r ) after exposure to light after removal by a light eraser (5) are respectively measured by a probe (4). After measuring and repeating the above process 5000 times
V _o , V _i and V _r were measured, and the repetition characteristics were examined.

 The results are shown in Table 2.

Effects of the Invention The photoreceptor of the present invention can improve sensitivity and repetition stability without lowering charge retention ability, and can obtain high image stability.

[Brief description of the drawings]

 FIG. 1 is a diagram showing a schematic configuration of a photoconductor tester.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kimiyuki Ito 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka Kokusai Building Minolta Camera Co., Ltd. (72) Inventor Yuki Shimada Chuo-ku, Osaka-shi, Osaka 2-3-3 Azuchicho Osaka Kokusai Building Minolta Camera Co., Ltd. (56) References JP-A-60-177355 (JP, A) JP-A-58-120258 (JP, A) (58) Fields investigated ( Int.Cl. ⁶ , DB name) G03G 5/05

Claims (2)

(57) [Claims] 1. A single-layer photosensitive layer containing a charge generating substance, a charge transporting substance and a pyrazoline fluorescent whitening agent, or a charge transporting substance and a pyrazoline fluorescent whitening agent on a conductive support. A photoreceptor having a laminated photosensitive layer in which a charge transport layer and a charge generation layer containing a charge generation substance are laminated, wherein the pyrazoline-based fluorescent whitening agent has the following general formula [I]; [Wherein, R ₁ represents a hydrogen atom, a lower alkyl group, or a halogen atom, and R ₂ represents a lower alkyl group, a —SO ₃ Na group, a —SO ₂
It represents an NH ₂ group or a —COOCH ₃ group, and R ₃ represents a hydrogen atom or an aryl group. Provided that R ₃ is an aryl group and R ₂ is a lower alkyl group]. 2. The photoreceptor according to claim 1, wherein the amount of the pyrazoline-based fluorescent whitening agent is based on the amount of the charge transporting substance.
A photoreceptor having 0.1 to 40% by weight.