JPH1195472A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which does not generate interference fringes and black spots and ensures satisfactory image characteristics using laser light absorbing material in a substratum. SOLUTION: A substratum 2 contg. a binder resin and 0.3-30 pts.wt. 1- methylamino-4-o-tolylaminoanthraquinone based on 100 pts.wt. of the binder resin and a photosensitive layer 6 are laminated on an electrically conductive substrate 1 to obtain the objective electrophotographic photoreceptor. An inorg. filler may further be incorporated into the substratum 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated organic electrophotographic photoreceptor using coherent light as a light source, and more particularly to an electrophotographic photoreceptor having good image quality without occurrence of interference fringes and image defects. .

[0002]

2. Description of the Related Art An electrophotographic photosensitive member used in an electrophotographic application apparatus using the Carlson method, such as a copying machine, a printer, and a facsimile, has conventionally been made of inorganic light such as selenium, selenium alloy, zinc oxide, and cadmium sulfide. Many used conductive materials. Recently, photoconductors using organic photoconductive materials have been actively developed, taking advantage of their non-polluting properties, film-forming properties, and light weight. Above all, the so-called stacked type organic electrophotographic photoreceptor in which the functions are separated into a charge generation layer and a charge transport layer, the sensitivity can be greatly improved by using a substance optimal for the function of each layer, and the desired exposure It has many advantages such as the ability to set spectral sensitivity according to the wavelength of light, and has become the mainstream of photoconductors.

[0003] Many of the laminated organic electrophotographic photoreceptors currently in practical use have a charge generation layer and a charge transport layer laminated on a conductive substrate in this order. Such a photoreceptor disperses and dissolves a charge generating substance in a solvent together with a binder, applies a coating liquid in which the coating is dried, forms a charge generating layer, and subsequently forms a coating liquid in which a charge transporting substance is dissolved in a solvent together with a binder. Is applied and dried to form a charge transport layer.

[0004] Even if the charge generation layer and the charge transport layer are directly laminated on the substrate as described above, basic performance as a photoreceptor can be obtained. However, the charge generation layer is extremely thin, generally 0.5 μm or less, in order to quickly inject charge carriers generated by absorbing light into the substrate and the charge transport layer. This causes film defects such as pinholes and film unevenness, and causes image defects such as black spots and density unevenness on the image. In addition, since the charge injection preventing property between the substrate and the charge generation layer is not sufficient, holes injected from the substrate lower the charge retention of the photoreceptor, causing a background fog on white paper.

It is known to provide a subbing layer made of a resin between a conductive substrate and a photosensitive layer in order to eliminate such film formation unevenness of the charge generation layer and image defects due to hole injection from the substrate. ing. Known resins used for the undercoat layer include solvent-soluble polyamide, polyvinyl alcohol, polyvinyl butyral, and casein. The undercoat layer using these resins may be 0.1 μm in some cases.
Even an extremely thin thin film having a thickness of m or less can sufficiently fulfill its charge injection preventing function. However, a film thickness of 0.5 μm or more is required to cover the surface defects and stains on the surface of the conductive substrate and eliminate the unevenness in the formation of the charge generation layer. Depending on the surface roughness of the substrate and the state of contamination, , A film thickness of 1 μm or more is required.

However, when such a thick undercoat layer is formed, the injectability of carriers generated in the charge generation layer is deteriorated, and a residual potential is increased upon repeated use. Defects occur. As an undercoating layer having a low electric resistance even with a layer having such a thickness and having a small fluctuation in electric resistance with respect to a change in the surrounding environment, for example, a case where a solvent-soluble polyad resin for specifying a chemical structure is used is disclosed in Japanese Patent Application Laid-Open No. HEI 9-163572. JP-A-2-193152, JP-A-3-28815
And JP-A-4-59870, and JP-A-2-59458 and JP-A-3-150572, which use a polyamide resin which suppresses a change in electric resistance to the environment by adding an additive. JP-A-2-530
JP-A-3-145652 and JP-A-3-145652 disclose examples in which a polyamide resin and another resin are mixed and used to further adjust the electric resistance and suppress the influence of the environment.
Japanese Patent Application Laid-Open No. 81778/1990 and Japanese Patent Application Laid-Open No. 2-281262 / 1990.

As an example of using other substances, Japanese Patent Application Laid-Open No. 2-238449 discloses an example using a cellulose derivative, and Japanese Patent Application Laid-Open No. 2-11 uses an example using polyether urethane.
Japanese Patent Laid-Open Nos. 5858 and 2-280170 disclose examples of using polyvinylpyrrolidone.
Japanese Patent Application Laid-Open No. 2-79859 discloses an example using polyglycol ether.

When such an undercoat layer is used in a laser beam printer, it is necessary to prevent image defects of interference patterns caused by the refractive index and thickness of the photosensitive layer and the wavelength of the light source. For this purpose, it has been generally proposed to add an inorganic pigment filler. For example, JP-A-3-24558 discloses an example of adding fine-particle aluminum oxide in a large amount of rutile-type titanium oxide in acrylic melamine. Is reported in JP-A-2-67565. Further, in order to improve the dispersibility and electric properties of the filler, an example has been proposed in which anatase-type titanium oxide having a purity of 99% or more is blended with an undercoating layer having a thickness of 2 to 10 μm. Japanese Patent Application Laid-Open No. 4-172361 discloses that anatase-type titanium oxide is more preferable than rutile-type titanium oxide.

[0009]

However, if a necessary amount of filler is added to prevent interference fringes, the uniformity of the surface of the undercoat layer is impaired, and the injection of charge from the charge generation layer becomes non-uniform. The density is reduced and black spots on white paper are generated. Further, when the undercoat layer of the filler dispersion system is formed by dipping coating, there is a problem that the pot life is short because the filler in the coating liquid is settled or agglomerated. Further, the undercoat layer having a low concealing property of the substrate can be used by cutting the surface of the substrate to scatter the reflected light, but the cutting process causes an increase in the cost of the substrate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide an electrophotographic photoreceptor having good image characteristics without interference fringes or black spots, using a laser light absorbing material for an undercoat layer. is there.

[0011]

According to the present invention, there is provided an electrophotographic photoreceptor having an undercoat layer and a photosensitive layer laminated on a conductive substrate according to the present invention, wherein the undercoat layer is 1-methylamino-4-layer. This is achieved by containing o-tolylaminoanthraquinone and a binder resin. In the above invention, the addition amount of 1-methylamino-4-o-tolylaminoanthraquinone is in the range of 0.3 to 30 parts by weight based on 100 parts by weight of the binder resin, or an inorganic filler is added to the undercoat layer. Is valid.

When writing an image using coherent light such as laser light, light incident on the undercoat layer may be reflected on the substrate to produce interference fringes. This occurs because the surface of the conductive substrate is not sufficiently covered by the undercoat layer.
When 1-methylamino-4-o-tolylaminoanthraquinone, which absorbs at a predetermined wavelength of laser light, is added to the undercoat layer, 1-methylamino-4-o-tolylaminoanthraquinone transmits light through the undercoat layer. Absorbs the reflected light from the substrate.

When an inorganic filler is added in addition to 1-methylamino-4-o-tolylaminoanthraquinone, it is effective to prevent interference fringes even if the amount of the filler is reduced. Is smoothed and the charge injecting property is improved.

[0014]

FIG. 1 is a sectional view showing a negatively charged laminated electrophotographic photosensitive member according to the present invention. FIG. 2 is a sectional view showing a positively charged single-layer type electrophotographic photoconductor of the present invention. 1
Is a conductive substrate, 2 is an undercoat layer, 3 is a charge generation layer, 4 is a charge transport layer, and 6 is a photosensitive layer.

The undercoat layer is a blue dye, 1-methylamino-4-o-
Tolylaminoanthraquinone (1-methylamino-4-o-tolylaminoanthra
quinone). 1-methylamino-4-o-tolylaminoanthraquinone absorbs laser light at a wavelength of 780 nm. The chemical formula of 1-methylamino-4-o-tolylaminoanthraquinone is shown below.

[0016]

Embedded image A binder resin is added to the undercoat layer in order to improve the adhesion to the conductive substrate and to increase the resistance of the undercoat layer to a solvent when the charge generation layer is provided on the undercoat layer. As the binder resin, polyamide resin, polyester resin,
Polyurethane resin, polycarbonate resin, epoxy resin, vinyl chloride resin, acrylic resin, polyvinyl ketal resin, phenol resin, urea resin, melamine resin, guanamine resin, furan resin and the like are used. When the undercoat layer is formed by dipping coating, the binder resin used for the undercoat layer is preferably a thermosetting resin in order to increase the resistance of the undercoat layer to a solvent.

The amount of 1-methylamino-4-o-tolylaminoanthraquinone added to the binder resin is in the range of 0.3 to 30 parts by weight based on 100 parts by weight of the binder resin. When such an undercoat layer is used in a laser beam printer, the surface properties of the undercoat layer should not be impaired to prevent interference fringes caused by the refractive index and thickness of the photosensitive layer and the wavelength of the light source.
It is possible to add an inorganic pigment filler in combination with -methylamino-4-o-tolylaminoanthraquinone. Examples of such a pigment include titanium oxide, zinc oxide, alumina, silica and the like. The amount of inorganic pigment added is 100 for the binder resin.
0 to 200 parts by weight based on parts by weight.

The thickness of the undercoat layer is preferably 0.3 to 30 μm in consideration of the uniformity of the coating film at the time of film formation. The compositions obtained by these combinations can be provided by applying a dilute solution of these compositions on a conductive substrate. As a coating method, a known method such as a dipping method, a doctor blade, a bar coater, a roll transfer method, and a spray method is used, and the dipping method is particularly preferable for coating on a cylindrical conductive substrate.

The conductive substrate is a known aluminum alloy such as JIS3003, JIS5000 or JIS600.
In addition to system 0, metal, resin, film with conductivity,
Paper or the like is used. These conductive substrates are finished to a predetermined dimensional accuracy by extrusion or drawing of aluminum or injection molding of resin. The surface of this conductive substrate is finished to an appropriate surface roughness by cutting with a diamond bite or the like, if necessary. If necessary, it is possible not to perform cutting. Thereafter, cleaning is performed in order to remove the cutting oil or the like used in the drawing process or the cutting process and obtain a clean conductive substrate surface. At this time, a water-based cleaning such as a weak alkaline detergent is used in place of the conventional chlorine-based organic solvents such as trichlene and chlorofluorocarbon.

The charge generating substance used in the charge generating layer is not particularly limited as long as it has a photosensitivity to the wavelength of the light source. Examples thereof include phthalocyanine pigments, azo pigments, quinacridone pigments, indigo pigments, and perylene pigments. ,
Organic pigment conductive substances such as polycyclic quinone pigments, anthantrone pigments and benzimidazole pigments are used. These substances are used by dispersing or dissolving them in various binder resins such as polyester resin, polyvinyl acetate, polymethacrylate resin, polycarbonate resin, polyvinyl butyral resin, and phenoxy resin. In this case, the mixing ratio is 30 to 500 parts by weight with respect to 100 parts by weight of the binder resin, and the film thickness is usually preferably 0.1 to 0.6 μm.

The charge transport layer is formed of, for example, an enamine compound,
A solution of a styryl compound, an amine compound, a butadiene compound, etc., together with a resin having good compatibility with them, for example, a polyester resin, a polycarbonate resin, a polymethacrylate resin, a polystyrene resin, etc., is applied in a dry film thickness of 10 to 40 μm. Formed. If necessary, an antioxidant, an ultraviolet absorber, a leveling agent and the like can be added.

The photosensitive layer 6 composed of a single layer is obtained by binding a charge generating substance and a charge transporting substance with a binder resin such as carbonate.

[0023]

【Example】

Example 1 Next, an undercoat layer coating solution described below was applied on an aluminum conductive substrate having an outer diameter of 30 mm and a length of 255 mm, and dried at 140 ° C. for 15 minutes to form a 5 μm undercoat layer.

The undercoat layer coating liquid is a melamine resin (trade name:
Uban 2020; 10 parts by weight of Mitsui Toatsu Chemical Co., Ltd.) is dissolved in a mixture of 50 parts by weight of methanol and 50 parts by weight of methylene chloride, and 1 part by weight of 1-methylamino-4-o-tolylaminoanthraquinone is further dissolved. In addition, it was prepared. Next, the following charge generation layer coating solution is applied on the undercoat layer by dipping coating,
Drying was performed at 100 ° C. for 10 minutes to form a charge generation layer.

The coating liquid for the charge generation layer is X-type phthalocyanine 2
Parts by weight and 98 parts by weight of a polyvinyl butyral resin solution dissolved in tetrahydrofuran THF were mixed and dispersed by ball milling for 30 hours to prepare. Next, the following charge transport layer coating solution was applied on the charge generation layer by dipping coating, and dried at 100 ° C. for 30 minutes to provide a charge transport layer having a thickness of 20 μm, thereby producing a photoreceptor.

The coating solution for the charge transport layer is composed of 10 parts by weight of a hydrazone compound (trade name: CTC191; manufactured by Anan Kosetsu) and 10 parts by weight of polycarbonate (trade name: L-1225; manufactured by Teijin Chemicals).
It was prepared by uniformly dissolving parts by weight in 80 parts by weight of dichloromethane. Example 2 A photoconductor was prepared in the same manner as in Example 1, except that a nylon resin (trade name: CM4000; manufactured by Toray Industries, Inc.) was used instead of the melamine resin. Example 3 In Example 1, titanium oxide A (trade name: TTO-5) was used.
5; manufactured by Ishihara Sangyo Co., Ltd .; primary particles having a particle size of 20 to 50 nm) were added in the same manner as in Example 1 except that 10 parts by weight were added. Comparative Example 1 A photoconductor was prepared by the same way as that of Example 1 except that the undercoat layer was formed without using 1-methylamino-4-o-tolylaminoanthraquinone. Comparative Example 2 A photoconductor was prepared by the same way as that of Example 2 except that the undercoat layer was formed without using 1-methylamino-4-o-tolylaminoanthraquinone. Comparative Example 3 A photoconductor was prepared by the same way as that of Example 3 except that the undercoat layer was formed without using 1-methylamino-4-o-tolylaminoanthraquinone. Comparative Example 4 In Example 3, an undercoat layer was formed without using 1-methylamino-4-o-tolylaminoanthraquinone.
A photoconductor was prepared by the same way as that of Example 3 except that titanium oxide B (manufactured by Fuji Electric Co., Ltd .; primary particle size: 1000 μm) was used instead of the undercoat layer.

The photoreceptor produced as described above is mounted on a laser beam printer, under a normal temperature and normal humidity environment of 25 ° C. and 50% RH, in a low temperature and low humidity environment of 10 ° C. and 20% RH, and at 30 ° C. and 90% RH. Tables 1, 2 and 3 show the results of a printing test performed in a high-temperature and high-humidity environment of% RH and results of continuous printing of 50,000 sheets under each environment.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3] The photoreceptors of Examples 1 to 3 have good image quality without occurrence of interference fringes and black spots in a low-temperature, low-humidity, normal-temperature, normal-humidity, high-temperature, high-humidity environment, and even when repeatedly used in the above-described environment. It can be seen that there is no image defect and high reliability.

[0031]

According to the present invention, the undercoat layer is 1-methylamino-
Because it contains 4-o-tolylaminoanthraquinone and a binder resin,
1-Methylamino-4-o-tolylaminoanthraquinone absorbs light transmitted through the undercoat layer and light reflected from the substrate, eliminating interference fringes in low-temperature, low-humidity, normal-temperature, normal-humidity, and high-temperature, high-humidity environments. An electrophotographic photoreceptor is obtained. 1-methylamino-4-o-tolylaminoanthraquinone
The use of the compound enhances the concealability of the substrate, eliminates the need to cut the surface of the substrate to scatter the reflected light, and reduces the manufacturing cost of the electrophotographic photosensitive member.

When an inorganic filler is added in addition to 1-methylamino-4-o-tolylaminoanthraquinone, even if the amount of the filler is reduced, it is effective in preventing interference fringes, and the surface of the undercoat layer can be effectively prevented. And the charge injecting property is improved, and an electrophotographic photoreceptor having good image quality without black spots is obtained. When the addition amount of the inorganic filler is small, an inorganic pigment which could not be used conventionally because of a low substrate hiding power, or an inorganic pigment having a particle diameter of not more than the wavelength of visible light can be used, and the electrophotographic photoreceptor can be used. Manufacturing becomes easier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a negatively charged laminated electrophotographic photoreceptor of the present invention.

FIG. 2 is a sectional view showing a positively charged single-layer type electrophotographic photoreceptor of the present invention.

[Description of Signs] 1 conductive substrate 2 undercoat layer 3 charge generation layer 4 charge transport layer 6 photosensitive layer

Claims (3)

[Claims] 1. An electrophotographic photoreceptor comprising an undercoat layer and a photosensitive layer laminated on a conductive substrate, wherein the undercoat layer is 1-methylamino-4-
A photoconductor for electrophotography, comprising o-tolylaminoanthraquinone and a binder resin. 2. The electrophotographic photoconductor according to claim 1, wherein the amount of 1-methylamino-4-o-tolylaminoanthraquinone is in the range of 0.3 to 30 parts by weight based on 100 parts by weight of the binder resin. 3. The electrophotographic photoconductor according to claim 1, wherein an inorganic filler is added to the undercoat layer.