JPH0530264B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a photoreceptor used in an electrophotographic copying machine, and particularly to a laminated electrophotographic organic photoreceptor having a charge generation layer and a charge transport layer. (Prior Art) As electrophotographic photoreceptors, there are those using inorganic photoconductors and those using organic photoconductors. Photoconductors using organic photoconductors have come into widespread use in recent years because they have advantages such as non-pollution, high productivity, and low cost. However, among organic photoconductors, substances that absorb visible light and generate electric charge have poor charge retention ability; It has the disadvantage that it has almost no photoconductivity. In order to solve this problem, the photosensitive layer has been made into a laminated type with functions separated into a charge generation layer that absorbs visible light and generates charges, and a charge transport layer that transports the charges. There is. By doing so, it becomes possible to individually select the charge generation material and the charge transport material.
The selection criteria for each material can be expanded. Conventionally, charge-generating materials include polycyclic quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, quinacridone pigments, phthalocyanine pigments, monoazo pigments, disazo pigments, trisazo or polyazo pigments, and charge-transporting materials. Known materials include amine compounds, hydrazone compounds, pyrazoline compounds, oxazole compounds, oxadiazole compounds, stilbene compounds, and carbazole compounds. For example, Japanese Patent Application Laid-Open No. 47-30330 describes the use of perylene pigment as a charge-generating material,
Also described are various hole transport materials and electron transport materials. (Problems to be Solved by the Invention) By the way, in order to obtain satisfactory electrophotographic properties in a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are functionally separated, 1. Charge generation material. It is necessary to satisfy the following conditions: (2) the generated charges are efficiently injected into the charge transport material and transported. That is, even if condition 1 is satisfied, if condition 2 is not satisfied, satisfactory photoresponsiveness cannot be obtained. In addition, when an electrophotographic photoreceptor is one in which a charge generation layer and a charge transport layer are laminated in this order, and light irradiation is performed from the charge transport layer side, the conditions that must be met in order to obtain high sensitivity are: It is necessary that the transport layer be sufficiently transparent to the light that activates the charge generating layer. In order to produce an electrophotographic photoreceptor using the above-mentioned known charge-generating materials and charge-transporting materials, the above-mentioned conditions must be satisfied, sensitivity, acceptance potential, potential retention, potential stability, residual Satisfied in all aspects, including electrophotographic properties such as potential and spectral properties, usage properties such as strength, durability, and stain resistance, and manufacturing stability and quality stability when manufactured by coating. material must be selected. However, it is extremely difficult to select a combination of materials that satisfies all of these points. The present invention has been made in view of the above circumstances, and it is possible to create an excellent electrophotographic photoreceptor by finding a combination of materials that satisfies all of the requirements for an electrophotographic photoreceptor. The purpose is to provide (Means and effects for solving the problems) The above-mentioned object of the present invention is to use at least one perylene pigment as a charge generation material of the charge generation layer and a charge transport material of the charge transport layer according to the following general formula:
At least one compound represented by (A) is used, and the charge transport layer is poly(4,4'-cyclohexylidene-diphenylene carbonate) or 4,4'-cyclohexylidene-diphenylene carbonate.
This is achieved by containing a polycarbonate resin which is a copolymer resin consisting of 4'-isopropylidene-diphenylene carbonate units and 4,4'-cyclohexylidene-diphenylene carbonate units. (However, R ₁ to R ₆ are each hydrogen atom, 1 to
selected from the group consisting of alkyl groups having 4 carbon atoms and chlorine atoms. ) The perylene pigment used in the present invention is
3.4.9.10-perylenetetracarboxylic acid and amine,
It is a reaction product with an amide or hydrazine compound, and is represented by the structural formula of the following general formula (B). (However, Q is an alkyl, aryl, or alkoxyl group that may have a substituent, a halogen atom, or a heterocyclic group.) Specifically, the following can be exemplified. The characteristics of these perylene pigments are that they have high light absorption and can generate and emit electric charges with high efficiency.
The pigment has high chemical stability and is not easily deteriorated by heat or light, has good dispersibility, and has good stability as a paint. A single type of perylene pigment may be used, but in order to expand the sensitive wavelength range, multiple types of perylene pigments having different spectral absorption wavelengths can also be used.
In the present invention, the particle size of these perylene pigments is
It is preferably 2 μm or less. Binder resins for dispersing perylene pigments include well-known ones, such as polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylic acid ester polymers or copolymers,
Vinyl acetate polymers or copolymers, cellulose esters or ethers, polybutadiene, polyurethane, epoxy resins, etc. are used. In the present invention, a compound represented by the general formula (A) is used as the charge transport material in the charge transport layer. Since this compound does not have film-forming properties by itself, it is used in combination with a resin that has good film-forming properties.In the present invention, poly(4,4'-cyclohexylidene-diphenylene carbonate) or , 4'-isopropylidene-diphenylene carbonate unit and 4,4'-cyclohexylidene-
A polycarbonate resin, which is a copolymer resin consisting of diphenylene carbonate units, is used. Regarding these polycarbonate resins,
It is described in detail in ``Plastic Materials Course 5 Polycarbonate Resin'' (published by Nikkan Kogyo Shimbun in 1962). Polycarbonate Z, which is poly(4,4'-cyclohexylidene-diphenylene carbonate), is represented by the following general formula (C). polycarbonate Z and 4,4'-isopropylidene-diphenylene carbonate units and 4,
A copolymer resin composed of 4'-cyclohexylidene-diphenylene carbonate units is preferable because it has a high melting point and a high glass transition point, so there is little change in properties with respect to temperature changes around room temperature, and it also has high mechanical strength. Furthermore, since the crystallinity of the molecule is low and the stability when made into a solution is high, it is convenient for coating. To explain in more detail the method for producing the electrophotographic photoreceptor of the present invention, first, the charge generation layer is formed by dispersing a perylene pigment in a binder resin solution and coating the solution. As the dispersing means, commonly used ones such as a ball mill, roll mill, sand mill, attritor, etc. can be used. The blending ratio of perylene pigment and binder resin is 40:1 to 1:
4, preferably 20:1 to 1:2. If the ratio of perylene pigment is too high, the stability of the coating solution decreases, and if it is too low, the sensitivity decreases, so it is desirable to keep it within the above range. Further, as the solvent for the binder resin, any solvent can be used as long as it is soluble, but it is desirable to select a solvent that has good pigment dispersibility. Further, a plurality of solvents may be used in combination. The charge transport layer is formed by dissolving the compound represented by the general formula (A) and the polycarbonate resin in a solvent that dissolves both, and applying the solution. The blending ratio of the former and the latter is 5:1 to 1:5, preferably 3:1 to 1:3. If the former ratio is too high, the mechanical strength of the charge transport layer will decrease, and if it is too low, the sensitivity will decrease, so it is desirable to keep it within the above range. The layer structure of the photosensitive layer in the electrophotographic photoreceptor of the present invention includes a charge transport layer 3 provided on a charge generation layer 2 as shown in FIG. 1, and a charge transport layer 3 provided on a charge generation layer 2 as shown in FIG. In some cases, a charge generation layer 2 is provided on the charge transport layer 3. Since the compound of general formula (A) is a hole-transporting substance, it is used with a negative charge in the former case, and with a positive charge in the latter case. The thickness of the charge generation layer is about 0.05 to 5 μm, and the thickness of the charge transport layer is about 5 to 50 μm. On the other hand, as shown in FIGS. 3 and 4, in the electrophotographic photoreceptor of the present invention, it is preferable to provide a barrier layer 4 between the photosensitive layer and the substrate 1. The barrier layer is
This is effective for preventing unnecessary charge injection from the substrate, and has the effect of increasing the chargeability of the photosensitive layer. Furthermore, it also has the effect of improving the adhesion between the photosensitive layer and the substrate. Materials constituting the barrier layer include polyvinyl alcohol, polyvinylpyrrolidone, polyvinylpyridine, cellulose ethers, cellulose esters, polyamide, polyurethane,
casein, gelatin, polyglutamic acid, starch,
Examples include starch acetate, aminostarch, polyacrylic acid, and polyacrylamide.
The resistivity of these materials is preferably about 10 ⁵ to 10 ¹⁴ Ω·cm. The thickness of the barrier layer is set to about 0.05 to 2 μm. (Example) Next, the present invention will be explained by using Examples and Comparative Examples. Examples 1 to 4 In these Examples, pigments having the following structural formulas were used as perylene pigments. Polyester resin (product name Adhesive)
49000, manufactured by Du Pont) 4g of cyclohexanone
80 g of the perylene pigment was mixed therein, and then dispersed using a sand grinder for 2 hours. 40 g of methyl ethyl ketone was added to 60 g of the obtained dispersion to prepare a coating solution, and
The coating was applied to the surface of an 84φ x 338mm aluminum pipe using a ring collar coating machine described in Japanese Patent No. 53-22544. Dry at 100℃ for 10 minutes,
A charge generation layer with a thickness of 0.4 μm was formed. Next, a compound having the following structural formula was prepared as a charge transport material. 10g of each compound and polycarbonate Z
(molecular weight 40,000 to 50,000) was dissolved in a mixture of 45 g of monochlorobenzene and 45 g of methylene chloride to obtain a coating liquid. This coating liquid was applied onto the charge generation layer using a ring color coating machine. at 110℃
It was dried for 30 minutes to form a charge transport layer with a thickness of 19 μm. The obtained electrophotographic photoreceptor drum was charged with a 5.9KV corona charger, and then white light was irradiated to attenuate the light, and the exposure amount E (erg/cm
₂ ) and the amount of potential attenuation V were measured, and the sensitivity (dV/dE) at the 1st and 50th rotations of the drum was determined. The results are shown in Table 1.

[Table] As is clear from Table 1, the photoreceptor drums of the present invention all have high sensitivity, and the fluctuations in potential and sensitivity between the 1st and 50th rotations are small, and they have excellent repeat stability. I can see that Comparative Examples 1 to 5 For comparison, tests similar to those in Example 1 were conducted on electrophotographic photosensitive drums whose charge transport layers were prepared using the following coating liquids. The results are shown in Table 2. Coating solution of Comparative Example 1 5 g of the same charge transport material as in Example 1
and polycarbonate A (product name Lexan 145,
(manufactured by GE, molecular weight: approximately 35,000 to 40,000) was dissolved in 35 g of methylene chloride. Coating solution for Comparative Example 2 15 g of polyvinyl carbazole (manufactured by BASF) and 5 g of polycarbonate Z (same as in Example 1) were dissolved in a mixture of 50 g of monochlorobenzene and 30 g of methylene chloride. Coating solution of Comparative Example 3: 12 g of tri(p-methylphenyl)amine and polycarbonate Z (same as in Example 1)
10 g was dissolved in a mixture of 40 g of monochlorobenzene and 30 g of methylene chloride. Coating liquid of Comparative Example 4 2,5-bis(p-diethylaminophenyl)
-11 g of 1,3,4-oxadiazole and 11 g of polycarbonate Z (same as in Example 1)
45g of monochlorobenzene and 45g of methylene chloride
It was dissolved in a mixture with g. Coating liquid of Comparative Example 5 1-pyridyl-(3)-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)
11 g of pyrazoline and polycarbonate Z (Example 1)
11g of monochlorobenzene
45 g of methylene chloride.

[Table] As is clear from Table 2, the electrophotographic photosensitive drum of Comparative Example 1 had good sensitivity, but
There is a large variation in sensitivity between the 1st rotation and the 50th rotation, and the repeatability is poor. Furthermore, it can be seen that the sensitivities of the electrophotographic photosensitive drums of Comparative Examples 2 to 4 are all inferior, and there is also a large variation in sensitivity between the 1st rotation and the 50th rotation. Example 5 In Example 1, before applying the charge generation layer to the aluminum pipe, an alcohol-soluble copolymerized nylon resin was previously applied to the pipe surface to a thickness of 0.5 μm to form a barrier layer. On top of this
Forming a photosensitive layer in the same manner as in Example 1,
An electrophotographic photoreceptor drum was created. This product was tested in the same manner as in Example 1. The results are shown in Table 3.

[Table] As is clear from the table above, it can be seen that the potential increases when a barrier layer is provided. (Effects of the Invention) In the present invention, by combining a charge generation layer containing a perylene pigment and a charge transport layer containing a compound represented by the above general formula (A) and the above specific polycarbonate resin, good charging properties can be achieved. The potential attenuation due to light irradiation is fast and the sensitivity is high, and the dependence of the potential attenuation on the electric field is small, making it easy to attenuate light even at a relatively low potential. That is, an electrophotographic photoreceptor can be obtained in which there is no trailing potential and almost no residual potential. In addition, the electrophotographic photoreceptor of the present invention has good potential stability, excellent repetition stability, low temperature and humidity dependence, and extremely low optical fatigue, and reduces chargeability due to light, so-called optical memory. It has the characteristics of being ineffective and very easy to use. The electrophotographic photoreceptor of the present invention is effectively used in electrophotographic copying machines, but can also be applied to various printers, microfilm readers, electrophotographic engraving systems, etc. that apply xerography technology. .

[Brief explanation of the drawing]

1 to 4 each show a schematic cross-sectional view of an electrophotographic photoreceptor of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Charge generation layer, 3... Charge transport layer, 4... Barrier layer.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photosensitive layer consisting of a laminate of a charge generation layer and a charge transport layer, wherein the charge generation layer contains at least one perylene pigment, and the charge transport layer has the following general formula: At least one compound represented by (A) and poly(4,4'-cyclohexylidene-diphenylene carbonate) or 4,
An electrophotographic photoreceptor comprising a polycarbonate resin which is a copolymer resin composed of 4'-isopropylidene-diphenylene carbonate units and 4,4'-cyclohexylidene-diphenylene carbonate units. (However, R ₁ to R ₆ are each hydrogen atom, 1 to
selected from the group consisting of alkyl groups having 4 carbon atoms and chlorine atoms. ).