JPH0743544B2 - Electrophotographic photoreceptor for reversal development - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member used in a reversal development type process.

(Prior Art) Image forming systems using electrophotography have been widely applied to the field of copying, and various excellent inorganic and organic photoconductors have been developed as photoconductors used in the system. ing.

On the other hand, recently, the digital signal data processing system has been developed and spread, and the function of a so-called printer that prints out these data is expected to be improved, and the use of an electrophotographic printing system in this field has been studied and put into practical use. Has been converted. That is, the signal data is converted into light by means such as a laser scanner, an LED array, or a liquid crystal shutter, and the light is irradiated onto the photoconductor to form a latent image on the photoconductor, which is visualized by toner development, It is the process of obtaining images and is also called an optical printer. This method is rapidly becoming popular because it has a much faster printing speed than the conventional impact method, has no noise, and enables high-quality printing.

Se, CdS are used as photoconductors for such optical printers.
Inorganic photoconductor such as polyvinylcarbazole (PV
K) and organic photoconductors such as CT complexes of trinitrofluorenone have been used, but it is easy to select the photosensitive wavelength range, especially to have sensitivity in the near infrared range, which is the output wavelength range of semiconductor lasers. The relatively easy organic photoconductor is very suitable and various materials have been developed. In particular, the laminated organic photoconductor consisting of the charge generation layer and the charge transfer layer makes full use of the abundance of organic compounds, and it is possible to obtain a high-sensitivity and high printing durability photoreceptor, and it is safe. It is also extremely useful in terms of properties and the ability to select non-polluting materials.

On the other hand, as an image forming method in an optical printer, a so-called reversal development method in which a toner is adhered to a portion irradiated with light to form an image is often adopted for the purpose of effectively utilizing light or enhancing resolution. In the reversal development process, the dark potential part becomes a white background and the bright potential part becomes a black background part (image area), but in this system, if there is a local charging failure due to a defect etc. on the photoconductor, a black spot on the white background Or, if there are a lot of them, it may cause development such as background fog.
It appears as a marked image defect. Even if such a local electrification defect does not cause any problem when it is used in a normal regular development, an image defect is likely to occur in the reversal development, and moreover, it is possible to obtain a laminated photosensitive film which has been conventionally obtained. It was found that the body had problems with black spots and fogging, to varying degrees.

There are various possible causes for this problem, namely, local charging failure, but it is considered that the injection of charges locally exceeds between the conductive support, which is an electrode, and the photosensitive layer, and the charging potential does not rise. In order to improve this, it is considered to provide a blocking layer between the conductive support and the photosensitive layer.

Providing such a blocking layer has been conventionally known as a known technique even in a photoreceptor for regular development, and as a material of the blocking layer, aluminum oxide,
Inorganic layers such as aluminum hydroxide and resin layers such as polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane and polyamide are used.

(Problems to be solved by the invention) However, when these conventional photoreceptors having a blocking layer are used in a reversal development type process, the background fog is remarkably unusable especially under high humidity environmental conditions. It turned out that

(Means for Solving Problems) As a result of intensive studies to solve the problems of background fog of the electrophotographic photosensitive member for reversal development as described above, the inventors have developed a polyamide resin having specific physical properties. It has been found that by using the layer, a reversal developing photoreceptor having good characteristics can be obtained without causing background fog under a wide range of environmental conditions including high humidity.

That is, the gist of the present invention is to provide a blocking layer on a conductive support,
A photoreceptor having a photosensitive layer in which a charge generation layer and a charge transfer layer are laminated, wherein the blocking layer has a saturated water absorption in water at 20 ° C. of 10% or less, and at least one of nylon 11 or 12 of 30 to 70. An electrophotographic photosensitive member for reversal development, characterized in that a main component is a copolyamide resin contained in a weight percentage.

According to the present invention, an electrophotographic photosensitive member for reversal development can be obtained in which an image with excellent fog resistance and a low fog can be obtained.

The present invention will be described in detail below.

The photoreceptor of the present invention is provided on a conductive support. Conductive supports include aluminum, stainless steel, copper,
Plate cylinder of metallic material such as nickel, plastic board with conductive layer made of aluminum, copper, palladium, nickel, chromium, tin oxide, indium oxide, etc. on the surface, insulating material such as cylinder, polyester film, paper Etc. are used.

The blocking layer (barrier layer) provided between the conductive support and the photosensitive layer has a saturated water absorption at 20 ° C in water.
A polyamide resin having less than 10% hygroscopicity is used. Here, the saturated water absorption is measured by the method shown in ASTM D570, and means the saturated value of the water absorption that increases with time after immersing the sample in 20 ° C. water, and indicates the degree of hygroscopicity of the polyamide resin. Represent. As a polyamide resin like this
11 Nylon and 12 Nylon are suitable because they have significantly lower water absorption than 6 Nylon and 66 Nylon. Further, it is preferable that the polyamide resin has good solubility in a solvent.
Copolymer nylon having nylon or 12 nylon as a main component is preferable. Examples of the copolymerization component include 6 nylon, 610 nylon, 66 nylon and the like, and a ternary or quaternary copolymer of these is preferable, but at least one of 11 nylon and 12 nylon is contained in an amount of 30 to 70% by weight. Copolymerized nylon is preferred. Polyamides obtained from azelaic acid and 1,10-decanedicarboxylic acid and piperazine can also be used as copolymerization components.

When a polyamide resin having a saturated water absorption of 10% or more is used as the blocking layer, fogging occurs at high temperature and high humidity. The saturated water absorption is preferably 10% or less, more preferably 7% or less.

Polyamide resin has a molecular weight of 5,000 to 30,000,
It is more preferably 10,000 to 20,000.

The thickness of the blocking layer is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2 μm. If necessary, other known resins and additives may be mixed in the blocking layer.

For the charge generation layer, Se and its alloys, As ₂ Se ₃ , cadmium sulfide, other inorganic photoconductors, and various organic pigments such as phthalocyanine and azo dyes can be used. Among them, metal-free phthalocyanine, copper, indium chloride, gallium chloride,
Metals such as tin, oxytitanium, zinc and vanadium or oxides thereof, phthalocyanines coordinated with chlorides,
Azo pigments such as monoazo, bisazo, trisazo and polyazos are preferred. The charge generation layer is formed as a layer having uniform physical properties or in a state where fine particles are dispersed in a binder. Examples of the binder resin used include phenoxy resin, epoxy resin, polyester resin, acrylic resin, polyvinyl butyral resin, and polycarbonate resin.

The film thickness is usually 0.1 μm to 1 μm, preferably 0.15 μm
m to 0.6 μm is preferable.

As the charge transfer material in the charge transfer layer, a polymer compound such as polyvinylcarbazole, polyvinylpyrene, polyacenaphthylene, or a low molecular compound such as various pyrazoline derivatives, oxazole derivatives, hydrazone derivatives, stilbene derivatives can be used. A binder resin is blended with these charge transfer materials as needed. Preferred binder resins include polymethylmethacrylate, polystyrene, vinyl polymers such as vinyl chloride resin and copolymers thereof, polycarbonate, polyester phenoxy resin, epoxy resin, silicone resin, and the like.
Also, partially cross-linked cured products thereof are used. The charge transfer layer may optionally contain various additives such as an antioxidant and a sensitizer. The film thickness of the charge transfer layer is usually 10
It is used in a thickness of -30 μm, more preferably 13 μm to 25 μm.

As described above, when the electrophotographic photosensitive member obtained according to the present invention is used in an electrophotographic system including a reversal development process, a good image free from fogging can be obtained under a wide range of environmental conditions including high humidity.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 Nylon 6/66/12 having a saturated water absorption of 6.6% in water at 20 ° C
Copolymer (copolymerization ratio 30/36/34 was dissolved in a mixed solvent of methanol and 70 to 30 parts by weight of n-propanol. To this solution was applied a mirror-finished aluminum drum by dipping and drying.
A 0.8 μm blocking layer was provided.

Next, 10 parts by weight of oxytitanium phthalocyanine and 5 parts by weight of polyvinyl butyral resin were mixed with 5 parts of 1,2-dimethoxyethane.
00 parts by weight was added, and the mixture was crushed and dispersed by a sand grind mill. An aluminum drum previously provided with a blocking layer was applied by dip coating to this dispersion, and a charge generation layer was provided so as to have a thickness of 0.3 μm after drying.

Next, this aluminum drum is treated with the hydrazone compound shown below.
100 parts by weight of polycarbonate resin (Novarex 7030A manufactured by Mitsubishi Kasei) and 1,4-dioxane 1000
The film thickness after dipping and coating in a liquid that has been dissolved in parts by weight is 20μ
A charge transfer layer was provided so as to have m. The obtained drum is referred to as a photoconductor A.

Next, for comparison, 6/66 was used as the blocking layer of polyamide.
/ 610 (copolymerization ratio is 46/38/16) is a nylon copolymer
A photoconductor B was prepared in exactly the same manner as in the above example except that a polyamide resin having a saturated water absorption at 20 ° C. of 12.5% was used.

Similarly, for comparison, let C be the comparative photoconductor similar to that of the example except that sodium caseinate was provided as a blocking layer in a thickness of 1 μm, and D is the comparative photoconductor without the blocking layer.
Each was created as.

The electrical characteristics of these photoconductors are shown in Table 1.

Next, these photoconductors were mounted on a commercial copying machine modified for reversal development, and the image characteristics in reversal development were evaluated. The results are shown in Table 1. With the photoconductor A of the present invention, a good image without fog and black spots was obtained under any condition, but with the photoconductor of the comparative example, both were markedly fogged under high temperature and high humidity. Was found, and it was found that it could not be put to practical use.

Example 2 6/66/11 copolymerized nylon (copolymerization ratio is 30/20/50) having a saturated water absorption rate in water at 20 ° C. of 3.6% was mixed with 60/25/10 parts by weight of methanol, trichlene and water. Dissolve in mixed solvent, dip and apply mirror-finished aluminum drum to this solution, 0.2μ
m blocking layer was provided, and a charge generation layer and a charge transfer layer were provided thereon in the same manner as in Example 1 to prepare a photoreceptor.
When this photoreceptor was subjected to reversal development in the same manner as in Example 1, an image without fog was obtained under both conditions of normal temperature and normal humidity and high humidity of 35 ° C. and 85% humidity.

Example 3 A 0.6 μm blocking layer of the polyamide resin used in Example 1 was provided on a mirror-finished aluminum cylinder,
Next, 4 parts by weight of a bisazo compound having the following structure, a polyvinyl butyral resin (Surex BH- manufactured by Sekisui Chemical Co., Ltd.
3) 2 parts by weight, 200 parts by weight of 1,2-dimethoxyethane Dispersion treatment was carried out with a sand grind mill to prepare a coating liquid, and a charge generation layer was formed on the blocking layer so as to have a thickness of 0.4 μm when dried. A charge transfer layer is provided on the charge generation layer thus obtained in the same manner as in Example 1 to form a photoconductor E.
It was created. For comparison, Sample F was prepared in exactly the same manner except that the blocking layer was not provided.

Image evaluation was carried out by reversal development using these photoconductors. As a result, a good image free from fogging was obtained with the photoconductor E of the present invention at 25 ° C. and 50% humidity and at 35 ° C. and 85% humidity. However, in sample F of the comparative example, no fog and good images were obtained under any environmental conditions.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Hiroi, 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryoh Chemical Industry Co., Ltd. Research Institute (72) Inventor Hiro Mori 1000 Kamoshida-cho, Midori-ku, Yokohama, Kanagawa Sanryoh Kasei Co., Ltd., Research Institute (72) Inventor Yoshihiro Tanaka 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Kogyo Co., Ltd., Research-lab (72) Inventor Setsuko Sasakawa Kamoshida-cho, Midori-ku, Yokohama, Kanagawa No. 1000 Sanryo Kasei Kogyo Co., Ltd. (56) References JP-A-60-227264 (JP, A) JP-A-60-218655 (JP, A) JP-A-52-25638 (JP, A) Special KOSHO 51-10355 (JP, B1)

Claims (1)

[Claims] 1. A photoreceptor having a photosensitive layer comprising a conductive support and a blocking layer, a charge generation layer and a charge transfer layer laminated thereon, wherein the blocking layer has a saturated water absorption in water at 20 ° C. of 10% or less. And an electrophotographic photoreceptor for reversal development, characterized in that the main component is a copolyamide resin containing 30 to 70% by weight of at least one of 11 and 12 nylon.