JPH0814707B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more specifically, to an electrophotographic apparatus having a conductive support and an undercoat layer having a function as an adhesive layer and a barrier layer. Regarding the photoconductor.

[Prior Art] Generally, in a Carlson type electrophotographic photosensitive member, stability of dark potential and light potential is important for forming a constant image density and a background-free image when charging and exposing are repeated. It has become.

Therefore, it has been proposed to provide a layer having a function as a barrier layer between the photosensitive layer and the conductive layer. Also,
It is proposed to have a laminated structure in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer, but in general, the charge generation layer is provided as an extremely thin layer on the conductive layer, for example, about 0.5 μm. The slightest defects, stains, deposits or scratches on the surface of the substrate cause the charge generation layer to have a non-uniform thickness.

If the film thickness of the charge generation layer is non-uniform, sensitivity unevenness occurs on the photoconductor, and therefore it is required to make the film thickness of the charge generation layer as uniform as possible.

Therefore, it has been proposed to provide an undercoat layer having a function as a barrier layer and a function as an adhesive layer between the charge generation layer and the conductive layer.

Up to now, it has been known to use polyurethane, polyamide, polyester, polyvinyl alcohol, epoxy resin, casein, methyl cellulose, nitrocellulose or phenol resin as a layer provided between the photosensitive layer and the conductive layer.

In the photoconductor using these layers as the undercoat layer, the potential is apt to change due to the influence of the temperature and humidity environment, the barrier function is lowered under high temperature and high humidity, and the potential of the dark part is lowered by the carrier injection from the support side. There is a defect that the density of the image becomes light.

Further, when such a photoconductor is used in an electrophotographic printer that performs reversal development, there is a problem that fog is likely to occur in an image under high temperature and high humidity.

Furthermore, a photoreceptor using a conventional material as the undercoat layer is likely to cause an increase in the bright part potential and a change in the dark part potential when repeatedly used, and particularly under an environment of low temperature and low humidity where the resistance of the undercoat layer becomes high. Since the electric charge remains in the layer, the potential of the bright portion is remarkably increased, and there is a drawback that a copy having a constant image quality cannot be obtained when continuously used.

[Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photosensitive member that can obtain a stable dark part potential largely in response to changes in temperature and humidity environment, and to provide a bright part potential even when repeatedly used. Another object of the present invention is to provide an electrophotographic photosensitive member that suppresses the rise of the temperature and the fluctuation of the dark part potential.

[Means and Actions for Solving Problems] In the present invention, in an electrophotographic photoreceptor having an undercoat layer between a conductive support and a photosensitive layer, the undercoat layer contains a cyanoethylated polysaccharide. And an electrophotographic photosensitive member.

The cyanoethylated polysaccharides used in the present invention include cellulose, starch, dextran, inulin,
Mannan, pullulan, cyclodextrin, pectin,
Examples include cyanoethylated products such as chitin, hydroxyethyl cellulose and sucrose.

The cyanoethylation rate of the above-mentioned polysaccharide cyanoyl compound can be represented by the cyanoethyl group substitution rate relative to all the hydroxyl groups in the raw material polysaccharide, and in the present invention, an arbitrary cyanoethylation rate is selected according to the characteristics of the photoreceptor. Can be used.

The undercoat layer in the present invention may be composed only of a cyanoethylated product of a polysaccharide, or may be composed of a plurality of components to which other resins and additives are added.

The undercoat layer preferably has a thickness of 0.1 to 10.0 μ, particularly 0.05 to 5.0 μ, and is applied by a method such as dip coating, spray coating or roll coating.

In the present invention, the photosensitive layer may be a single layer type or a laminated structure type in which the charge generating layer and the charge transporting layer are functionally separated.

The charge generation layer is azo pigments such as Sudan Red, Diane Blue, and Genus Green B, Argol Yellow,
Quinone pigments such as pyrenequinone and indanthrene brilliant violet RRP, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, bisbenzimidazole pigments such as Indian First Orange toner, phthalocyanine pigments such as copper phthalocyanine, and charges of quinacridone pigments. Disperse the generated substance in a binder resin such as polyvinyl butyral, polystyrene, polyvinyl chloride, polyvinyl acetate, acrylic resin, polyvinylpyrrolidone, methylcellulose, hydroxypropylmethylcellulose, etc., and disperse this dispersion on the above-mentioned undercoat layer. It can be formed by coating. The thickness of such a charge generation layer is 5 μm or less, preferably 0.01 to 1 μm.
Is appropriate.

The charge transport layer provided on the charge generation layer is a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, and coronene in the main chain or side chain or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiene. It is formed using a coating liquid in which a nitrogen-containing cyclic compound such as azole, pyrazoline, thiadiazole, and triazole, and a charge transporting substance such as a hydrazone compound are dissolved in a resin having a film-forming property.
This is because the charge transporting substance generally has a low molecular weight and is poor in film forming property by itself.

Such resins include polyester, polysulfone, polycarbonate, polymethacrylates,
Examples include polystyrene.

The thickness of the charge transport layer is 5 to 40μ, preferably 10 to 25μ.

As the photosensitive layer used in the present invention, in addition to the above, poly-N
Examples thereof include organic photoconductive polymer layers such as vinylcarbazole and polyvinylanthracene, selenium vapor deposition layers, selenium-tellurium vapor deposition layers, and amorphous silicon layers.

If the substrate used in the present invention has a conductive layer,
Any material may be used, and specific basic examples include, for example, aluminum, copper, vanadium, molybdenum, chromium, nickel, titanium, zinc, indium, brass, etc. molded into a drum or sheet, a metal such as aluminum or copper. Foil laminated to plastic film, aluminum, indium oxide, tin oxide, etc. deposited on plastic film, or conductive material such as metal powder, carbon black, copper iodide, or polymer electrolyte is properly bound. Examples include plastic films and papers that have been applied together with an agent resin and have their surfaces subjected to a conductive treatment.

The electrophotographic photoreceptor of the present invention can be used not only in an electrophotographic copying machine, but also in a laser printer CRT printer, an electrophotographic plate making system, and the like.

[Example] Example 1 4 parts of cyanoethylated cellulose (average degree of polymerization: 950, cyanoethylation rate: 82%) was dissolved in 100 parts of DMF to prepare an undercoat layer coating material.

The above-mentioned coating material for undercoat layer was applied by dip coating on a 60φ aluminum cylinder which is a conductive support, and dried at 100 ° C. for 30 minutes to form an undercoat layer having a film thickness of 1.5 μm.

Next, 10 parts of a disazo pigment having the following structural formula, 6 parts of a cellulose acetate butyrate resin (trade name CAB-381, manufactured by Eastman Co., Ltd.) and 60 parts of cyclohexanone were dispersed for 20 hours in a sand mill using 1φ glass beads.

To this dispersion, 100 parts of methyl ethyl ketone was added, dip-coated on the undercoat layer, and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a coating amount of 0.1 g / m ² .

Next, 10 parts of a hydrazone compound having the following structural formula, And 15 parts of styrene-methyl methacrylate copolymer (trade name: MS200, manufactured by Iron Manufacturing Co., Ltd.) was dissolved in 80 parts of toluene. This solution is applied onto the charge generation layer by dip coating at 100 ° C.
Was dried with hot air for 1 hour to form a charge transport layer having a thickness of 18 μm.

The electrophotographic photoconductor thus created was attached to the Canon Co., Ltd. copying machine PC-24, and it was stored at room temperature and normal humidity (21 ° C, 60% R
H) and electrophotographic characteristics were evaluated under high temperature and high humidity (33 ℃, 85% RH), and good image was obtained without fluctuation of dark area potential even under high temperature and high humidity. The results will be described later.

Comparative Example 1 Methoxymethylated nylon resin (trade name: Resin Resin EF-30T, manufactured by Teikoku Chemical Industry Co., Ltd.) 5 as the undercoat layer coating material
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a coating material dissolved in 95 parts of methanol was used and evaluated in the same manner. As a result, carrier injection from a conductive support under high temperature and high humidity was performed. Due to the increase, the dark area potential decreased, and the image density decreased. The results are shown.

Example 2 10 parts of ε-type copper phthalocyanine (manufactured by Toyo Ink Co., Ltd.), 5 parts of butyral resin (brand name S-REC BM-2, manufactured by Sekisui Chemical Co., Ltd.) and 50 parts of cyclohexanone were used as 1φ glass as a charge generation layer coating material. Example 3 except that the charge generation layer was formed by using a coating material prepared by adding 80 parts of methyl ethyl ketone after dispersing for 3 hours by a sand mill using beads.
An electrophotographic photosensitive member provided with an undercoat layer and a charge transport layer similar to the above was prepared.

The electrophotographic photoconductor thus created was attached to a laser beam printer LBP-CX manufactured by Canon Inc. under normal temperature and normal humidity (20 ° C, 55% RH) and high temperature and high humidity (32 ° C, 80%).
When the electrophotographic characteristics were evaluated by (RH), a good image without black spots and fog was obtained even under high temperature and high humidity.

 The results will be described later.

Comparative Example 2 Methoxymethylated nylon resin (trade name: Resin Resin EF-30T, manufactured by Teikoku Chemical Industry Co., Ltd.) 2 as a paint for the undercoat layer
Parts, alcohol-soluble copolymerized nylon resin (trade name: Amilan CM-8000, manufactured by Toray Industries, Inc.) 4 parts were dissolved in 94 parts of methanol to prepare an electrophotographic photoreceptor in the same manner as in Example 2. When prepared and evaluated in the same manner, under high temperature and high humidity, the dark area potential was lowered by carrier injection from the conductive support, and black spot-like fog was generated on the image. The results are shown.

Example 3 6 parts of cyanoethylated pullulan (average degree of polymerization: 600, cyanoethylation: 89%) was dissolved in 100 parts of DMF to prepare a coating material for the undercoat layer.

The above-mentioned coating material for undercoat layer was applied by dip coating on a 30φ aluminum cylinder which is a conductive support, and dried at 110 ° C. for 20 minutes to form an undercoat layer having a film thickness of 1.5 μm.

Next, 10 parts of a disazo pigment having the following structural formula, Disperse 8 parts of butyral resin (trade name S-REC BL-S, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone in a sand mill using 0.5φ glass beads for 5 hours, and then add 120 parts of tetrahydrofuran to prepare a dispersion liquid. did. This dispersion is dip coated on the undercoat layer at 80 ° C.
After drying for 20 minutes, a charge generation layer having a coating amount of 0.18 g / m ² was formed.

Next, 8 parts of a hydrazone compound having the following structural formula, And 10 parts of styrene-methyl methacrylate copolymer (trade name: MS200, manufactured by Iron Manufacturing Chemical Co., Ltd.) are dissolved in 70 parts of monochlorobenzene, and this solution is dip-coated on the charge generation layer and dried at 120 ° C for 50 minutes. Then, a charge transport layer having a thickness of 20 μm was formed.

The electrophotographic photoconductor thus created was attached to a copier FC-5 manufactured by Canon Inc., and it was stored under low temperature and low humidity (10 ° C, 10% R).
In H), 1,000 consecutive images were produced, and there was no increase in the light potential, and a very stable image was obtained. The results will be described later.

Comparative Example 3 An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 3 except that the coating material used in Comparative Example 2 was used as the coating material for the undercoat layer. The results will be described later.

Example 4 4 parts of cyanoethylated dextran (average degree of polymerization: 1350, cyanoethylation rate: 77%) was added to DMF1 as a coating for the undercoat layer.
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 3 except that the coating material dissolved in 00 parts was used.

 The results will be described later.

Example 5 An electrophotography was performed in the same manner as in Example 3 except that 4 parts of cyanoethylated mannan (average degree of polymerization: 2500, cyanoethylation rate: 92%) was dissolved in 100 parts of acetonitrile as the coating for the undercoat layer. A photoconductor was prepared and evaluated. The results will be described later.

Example 6 As the coating for the undercoat layer, a coating prepared by dissolving 6 parts of cyanoethylated sucrose (cyanoethylation rate 96%) and 2 parts of polyester (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) in 120 parts of MEK was used. An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 3. The results will be described later.

[Advantages of the Invention] The electrophotographic photoreceptor of the present invention contains the cyanoethylated product of the polysaccharide in the undercoat layer, so that there is almost no decrease in the barrier function under high temperature and high humidity and almost no increase in resistance under low temperature and low humidity. Excellent reduction in dark area potential under high temperature and high humidity and increase in bright area potential due to continuous use under low temperature and low humidity, which has been a problem with conventional electrophotographic photoreceptors having an undercoat layer. It is a thing.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having an undercoat layer between a conductive support and a photosensitive layer, wherein the undercoat layer contains a cyanoethylated product of a polysaccharide.