JPH08101522A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE: To obtain stable electrification property and low potential in a bright area without causing corrosion of an undercoat layer by the solvent in the a coating liquid for a charge producing layer by forming a specified undercoat layer between a conductive base body and a photosensitive layer containing an org. photoconductive material. CONSTITUTION: An undercoat layer 2 containing polyamide expressed by formula is formed between a conductive base body 1 and a photosensitive layer 5a containing an org. photoconductive material. In formula, A is an aromatic ring or alkyl group. This polyamide is an aromatic polyamide. It is effective to form the undercoat layer 2 between >=0.3μm or >=0.5μm and <=1μm thickness. The aromatic polyamide is produced by a well-known method. This aromatic polyamide is used by dissolving in a solvent such as N-methylpyrrolidone, pyridine, and DMSO. By this method, the electric conductivity of the undercoat layer is increased, which decreases the potential in bright area and decreases changes in electric properties in a high temp. and high humidity environment at 35 deg.C and 95%RH.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrophotographic photoreceptor, and more particularly to an undercoat layer provided between a conductive substrate and a photosensitive layer containing an organic photoconductive material.

[0002]

2. Description of the Related Art Currently, organic electrophotographic photoconductors (hereinafter referred to as photoconductors) are mainly used as photoconductors for laser beam printers and copying machines. The Carlson method is mainly applied to image formation using these photoconductors. Image formation by this method is performed by corona discharge to a photoconductor in the dark and exposing the charged photoconductor surface to form an electrostatic latent image.
The electrostatic latent image is developed by toner, and the developed toner image is fixed on paper or the like. After that, the photoconductor is reused after removing the charge, removing the residual toner, and removing the charge. The main characteristics required for these photoconductors are stability of charging due to corona discharge in the dark, fast and sufficient reduction of potential with a small amount of light, that is, high sensitivity and fast photoresponsiveness. . It is generally known to provide an undercoat layer between the conductive substrate and the photosensitive layer as a means for improving the stability of charging by corona discharge in the dark.

Further, there has been proposed one having a laminated structure in which a photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. Generally, the charge generation layer is an extremely thin layer of 0.2 to 1.5 μm. Therefore, defects (concavities and convexities) on the surface of the conductive substrate cause the charge generation layer to have a non-uniform thickness, resulting in image defects, and a local charge injection prevention function under high temperature and high humidity environmental conditions. There is a drawback that image defects occur due to deterioration. As a countermeasure against this, it has been proposed to provide an undercoat layer between the charge generation layer and the conductive substrate, which has a function of covering surface defects of the conductive substrate, a function of preventing charge injection, and a function as an adhesive layer. .

As materials for the undercoat layer used between the photosensitive layer and the conductive substrate, polyamides (JP-A-46-47344 and JP-A-52-25638) and polypeptides (JP-A-52-25638) have hitherto been used. JP-A-53-48523), casein (JP-A-55-103556),
Known materials include polyvinyl alcohol (Japanese Unexamined Patent Publication No. 52-100240), ethyl cellulose (Japanese Unexamined Patent Publication No. 55-143564), materials obtained by mixing polyamide or the like with conductive particles (Japanese Unexamined Patent Publication No. 2-74949). There is.
However, when the undercoat layer formed of these materials is applied to the photoconductor, the characteristics required for the photoconductor are not sufficiently satisfied under the present circumstances.

[0005]

When an undercoat layer made of polyamide is applied to a photoconductor, it has a thickness of 0.3 μm.
With the above film thickness, the initial bright part potential (VL) becomes high, and at the same time, the bright part potential (VL) rises even after repeated tests. Further, when the film thickness is 0.3 μm or less, when an aluminum drum which has been subjected to finishing such as mirror finishing using a diamond tool or the like is used as a conductive substrate, surface defects (unevenness, deposits) on the conductive substrate There is also a problem that image defects cannot be prevented due to a lack of the capability of the charge injection prevention function.

When the thickness of the undercoat layer is set to 0.3 μm or more, a method for preventing a rise in the light potential (VL) is as follows.
It has been proposed to use a mixture of conductive particles and a polymer such as polyamide, but it is possible to prevent the bright part potential (VL) from rising, but on the contrary, the function of preventing charge injection is lowered and the initial chargeability, that is, There is a drawback that the dark part potential (VO) is low, and a polyamide layer having a charge injection preventing function is also used.

Further, in the case of water-soluble polymers such as polypeptides, casein, polyvinyl alcohol, etc., 35 ° C, 95%
If the RH is left under high temperature and high humidity, there is a defect that image defects are generated and the adhesion is deteriorated. There is also a problem that the undercoat layer is attacked by the solvent of the coating liquid for the charge generation layer.

The present invention has been made in view of the above-mentioned problems, and an object thereof is that the undercoat layer is not attacked by the solvent of the coating liquid for the charge generating layer and has stable chargeability in repeated tests and low chargeability. Has bright part potential, 35 ° C: 95%
An object of the present invention is to provide a photoconductor for electrophotography having a good image under a high temperature and high humidity environment of RH.

[0009]

According to the present invention, the above object is to include a polyamide represented by the following general formula (I) between a conductive substrate and a photosensitive layer containing an organic photoconductive material. It is achieved by providing an undercoat layer formed by

[0010]

Embedded image

[In the formula, A represents an aromatic ring or an alkyl group. The polyamide is an aromatic polyamide, and the thickness of the undercoat layer is 0.3 μm or 0.5 μm or more,
It is effective that the thickness is 1 μm or less. Specific examples of the aromatic polyamide according to the present invention include compounds having the following structural formulas.

[0012]

Embedded image

The aromatic polyamide used in the present invention is produced by a known method disclosed in JP-A-6-93099. The aromatic polyamide used in the present invention includes N-methylpyrrolidone, pyridine, DMSO,
It is used by dissolving it in a solvent such as m-cresol.

[0014]

According to the structure of the present invention, since the aromatic polyamide is contained in the undercoat layer, the electric conductivity of the undercoat layer is improved by the good molecular dispersion in the undercoat layer and the ion doping. The degree will be greatly increased. Further, the increase in the electric conductivity realized in this way is due to the electron conduction, and the electric conductivity is stable, and the fluctuation of the bright part potential becomes extremely small. In addition, because of high heat resistance and low water absorption, 35 ° C: 9
There is little change in electrical properties under a high temperature and high humidity environment of 5% RH, and stable image characteristics are obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 are cross-sectional structural views each illustrating a photoconductor according to the present invention. FIG. 1 is a so-called negatively charged laminated type photoreceptor, which has a structure in which a photosensitive layer 5a in which an undercoat layer 2, a charge generation layer 3 and a charge transport layer 4 are laminated in this order is provided on a conductive substrate 1. FIG. 2 shows a so-called positively charged laminated type photoreceptor, in which an undercoat layer 2, a charge transport layer 4 and a charge generation layer 3 are laminated in this order on a conductive substrate 1, and a photosensitive layer 5b and an overcoat layer 6 are provided. belongs to. FIG. 3 shows a so-called positively charged single-layer type photoconductor in which an undercoat layer 2, a single photosensitive layer 5c made of a charge generating substance, a charge transporting substance and a resin binder is provided on a conductive substrate 1. is there.

The embodiments of the present invention will be described below with reference to the case of the negatively charged laminated type photoreceptor of FIG. 1, but the present invention is not limited thereto. As the conductive substrate 1, an aluminum cylinder or an aluminum vapor-deposited film is used. The charge generation layer 3 is composed of a charge generation substance and a resin binder. As the charge generating substance, various phthalocyanine compounds, azo compounds, polycyclic quinone compounds, squarylium compounds and the like can be used. As the resin binder for the charge generation layer 3, polycarbonate, polyester, polyamide, polyurethane, epoxy, polyvinyl butyral, polyvinyl acetal, phenoxy resin, silicone resin, acrylic resin, vinyl chloride resin,
Vinylidene chloride resin, vinyl acetate resin, homer resin,
Cellulose tree, or copolymers thereof, and halogen compounds or cyanoethyl compounds thereof are used.

Specific examples of the charge generating substance include compounds having the following structural formulas.

[0018]

[Chemical 4]

[0019]

Embedded image

[0020]

[Chemical 6]

[0021]

[Chemical 7]

[0022]

Embedded image

[0023]

[Chemical 9]

[0024]

[Chemical 10]

[0025]

[Chemical 11]

The charge transport layer 4 is composed of a charge transport material and a resin binder. As the charge transport material, a diamine compound, a hydrazone compound, or a stilbene compound can be used. As the resin binder for the charge transport layer 4, polycarbonate, polystyrene, polyphenyl ether acrylic resin or the like can be used. Hereinafter, specific examples will be described. Example 1 The compound No. 1 was prepared by the known method disclosed in JP-A-6-93099. I-1 is 100% polyamide (PA
1) was synthesized. The typical intrinsic viscosity at 30 ° C. measured with a 5 mg / ml sulfuric acid solution of synthesized PA1 is 1.1.
It was 5 dL / g. The compound No. I-1 is 100
% Polyamide (PA1) is dissolved in 150 parts by weight of N, N-dimethylformamide (DMF), and TiO 2 having an average particle diameter of 30 nm is used for the purpose of preventing image interference.
To prepare a coating solution for the undercoat layer 2 [A-1] dispersed ₂ 5 parts by weight was added with mixing and dispersing machine such as a paint shaker for 3 hours or more.

Next, the compound N is used as a charge generating substance.
o. 5 parts by weight of II-1 (metal-free phthalocyanine) and 5 parts by weight of polyvinyl acetal (trade name S-Rex KS-1: manufactured by Sekisui Chemical Co., Ltd.) as a binder were mixed with 700 parts by weight of dichloromethane and kneaded with a mixer for 3 hours. Then, a coating liquid for the charge generation layer 3 was prepared. Further, as a charge transport substance, the following compound No. 1 part by weight of the hydrazone compound represented by III-1 and 1 part by weight of polycarbonate (trade name Panlite L1225: manufactured by Teijin Chemicals) as a resin binder are dissolved in 8 parts by weight of dichlorotan to prepare a coating solution for the charge transport layer 4. It was made.

[0028]

[Chemical 12]

An aluminum alloy extruded drum having an outer diameter of 60 mm, a wall thickness of 1 mm and a length of 310 mm was ultrasonically cleaned with trichlene, and then the surface of the drum was rubbed with a sponge while dripping an alkaline cleaning solution containing a surfactant. Then, what was ultrasonically washed with warm pure water at 80 ° C. and dried was used as the conductive substrate 1. The coating liquid [A-1] was applied onto the conductive substrate 1 to form a film having a thickness of 0.3 μm and 0.5 μm, respectively.
m, 1 μm of the undercoat layer 2 is applied by the Dip method, and the coating liquid for the charge generation layer 3 is further applied thereon by 0.3 μm.
m, and the coating liquid for the charge transport layer 4 was sequentially applied to 20 μm to prepare photoconductors of Examples 1a to 1c. Comparative Example 1 As a material for the undercoat layer 2, polyamide (trade name CM
(8000: manufactured by Toray) 8 parts by weight are dissolved in 60 parts by weight of methyl alcohol, 30 parts by weight of n-butyl alcohol, and 10 parts by weight of dichloromethane, and further 5 parts by weight of TiO ₂ having an average particle diameter of 30 nm for the purpose of preventing image interference. Was added and dispersed for 3 hours or more with a mixing and dispersing machine such as a paint shaker to prepare a coating liquid [A-2] for the undercoat layer 2.

An undercoat layer 2 having a thickness of 0.3 .mu.m, 0.5 .mu.m and 1 .mu.m is coated on the conductive substrate 1 with the coating liquid [A-2] by the Dip method, and further a charge generating layer is formed thereon. The coating liquid for No. 3 was 0.3 μm, and the coating liquid for the charge transport layer 4 was then sequentially coated to 20 μm.
A photoconductor 1c was prepared. After visually evaluating the uniformity of the charge generation layer 3 of the photoconductor, the photoconductor was mounted on a laser printer and subjected to 1 environment under normal temperature and humidity (20 ° C .: 60% RH).
The running test was performed ten thousand times, and the images obtained by the change in the light potential (VL) and the dark potential (VO) and the reversal phenomenon were evaluated. Further, after leaving for 1 hour or more in a low temperature atmosphere of 5 ° C .: 60% RH and a high temperature and high humidity environment of 35 ° C .: 95% RH, the image obtained by the reversal phenomenon was evaluated. Table 1 shows the results.

[0031]

[Table 1]

As can be seen in Table 1, Examples 1a-1c.
Indicates that the light potential (VL) immediately after the start of the test is small, and the image obtained by the change in the light potential (VL) and the dark potential (VO) and the inversion phenomenon is good even after 10,000 running tests. The comparative example 1 is good, and the superiority of the present invention is clear. The thickness of the undercoat layer 2 is 0.3 μm or more, preferably 0.5 μm or more,
It can be seen that 1.0 μm or less is sufficient.

2 and the positively charged single layer type photoreceptor of FIG. 3, the thin charge generation layer 3 is the conductive substrate 1.
Since there is no image defect due to the surface defect of the conductive substrate 1 since it is not in the vicinity of, the application of the present invention has a stable high charging property and a low bright portion potential in the repeated test, and causes no optical interference. A photoconductor can be obtained which is free from image defects.

[0034]

According to the present invention, since the aromatic polyamide is contained in the undercoat layer, the electric conductivity of the undercoat layer can be improved by satisfactorily dispersing the molecules in the undercoat layer and realizing ion doping. The degree will be greatly increased. Further, the increase in the electric conductivity realized in this way is due to the electron conduction, and the electric conductivity is stable, and the fluctuation of the bright part potential becomes extremely small. In addition, because of high heat resistance and low water absorption, 35 ° C: 9
There is little change in electrical properties under a high temperature and high humidity environment of 5% RH, and stable image characteristics are obtained. As a result, the number of image defects is extremely reduced, and a stable image (high chargeability and low bright part potential) is obtained in a high temperature and high humidity environment, and stable high chargeability and low bright part in repeated tests are obtained. It is possible to obtain a photoconductor having an electric potential, which does not cause an image defect due to light interference and which has a sufficient adhesive force with the conductive substrate and the photosensitive layer.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a negative charging laminated type photoreceptor according to the present invention.

FIG. 2 is a cross-sectional configuration diagram of a positively charged laminated type photoreceptor according to the present invention.

FIG. 3 is a cross-sectional configuration diagram of a positively charged single-layer type photoconductor according to the present invention.

[Explanation of symbols]

 1 Conductive Substrate 2 Undercoat Layer 3 Charge Generation Layer 4 Charge Transport Layer 5a Photosensitive Layer 5b Photosensitive Layer 5c Photosensitive Layer 6 Overcoat Layer

Claims (3)

[Claims] 1. An electron having an undercoat layer containing a polyamide represented by the following general formula (I) between a conductive substrate and a photosensitive layer containing an organic photoconductive material. Photoreceptor for photography. Embedded image [In the formula, A represents an aromatic ring or an alkyl group. ] 2. The photoconductor for electrophotography according to claim 1, wherein the polyamide is an aromatic polyamide. 3. The photoconductor according to claim 1, wherein
The thickness of the undercoat layer is 0.3 μm or 0.5 μm
The electrophotographic photosensitive member is characterized by being 1 μm or less.