JPS62143059A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To remarkably enhance electrification characteristics and photosensitivity of a photosensitive body in a short time by adding an electron donor to an alpha-type metal-free phthalocyanine and milling it. CONSTITUTION:The electrophotographic sensitive body has a photosensitive layer containing as the carrier generating material the alpha-type metal-free phthalocyanine prepared by adding the electron donor and milling it. The electron donor to be used is an N-containing cyclic compound, preferably, one or more of phenanthroline derivatives or the like. This phthalocyanine is used as the carrier generating material to form the electrophotographic sensitive body of a function separation type, thus permitting electrification characteristics and photosensitivity to be remarkably enhanced, as compared with the photosensitive body using the alpha-type metal-free phthalocyanine not subjected to said milling treatment in the presence of said electron donor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing a metal-free phthalocyanine.

[Prior art and its problems]

Photoreceptors for electrophotography (hereinafter simply referred to as photoreceptors) must be able to be charged to the required potential in the dark by corona discharge, etc., and have little charge leakage (and must have the ability to quickly discharge when irradiated with light). Therefore, the photoconductive material used for the photosensitive layer of the photoreceptor must have a large band capacity in the dark, a low leakage current, and the ability to generate a large amount of carriers when irradiated with light. It is desired to have excellent transport ability to rapidly transport generated carriers.

Conventionally, as a photovoltaic material 4 having such performance,
Inorganic photoconductive materials such as amorphous selenium alloys, zinc oxide, and cadmium sulfide have been used, but in recent years, organic photoconductive materials such as R7
RF and sexual substances are attracting attention.

Furthermore, recently, there has been active research into functionally separated photoreceptors in which the performance of the photoreceptor is improved by assigning the aforementioned carrier generation function and carrier transport function to different substances. Many functionally separated photoreceptors have been proposed that use organic dyes or organic pigments as carrier-generating substances, such as azo pigments and phthalocyanine pigments, but they do not have sufficient fastness and light resistance. It is difficult to find a compound that has a high carrier-generating ability and has an excellent carrier-generating ability.

Among these, phthalocyanine pigments are known as crystal polymorphs that exist in a plurality of crystal forms. Among them, it has been reported that metal-free phthalocyanine has better photosensitivity than other phthalocyanine compounds (Japanese Patent Application Laid-Open No. 49-4338).
There are various attempts being made. All of these attempts are aimed at improving charging characteristics and photosensitivity by changing α-type metal-free phthalocyanine as a starting material to other crystal systems. However, these crystal changes have the problem that the process is complicated, such as the need to control the crystal within a limited temperature range.

In the process of crystallization control of α-type metal-free phthalocyanine, which was conventionally considered to be unsuitable as a photoreceptor as it is, the present inventors developed a method using a ball mill using glass poles as a dispersion medium without completely changing the crystal form. We have already proposed this method, focusing on the fact that improvements in charging characteristics and photosensitivity can be easily obtained simply by dry processing. However, this process requires
It takes a long time of 150 hours.

As a result of further studies, the present inventors found that by adding an electron-donating substance, specifically a nitrogen-containing cyclic compound, during the milling process as described above, charging characteristics and photosensitivity can be easily and quickly improved. It was discovered that a metal-free phthalocyanine capable of can be obtained, and the present invention was defeated.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art as described above, and to easily produce an electrophotographic photoreceptor having a photosensitive layer containing metal-free phthalocyanine as a carrier generating substance, which has excellent charging characteristics and photosensitivity. It is intended to be provided in a short period of time.

[Key points of the invention]

An object of the present invention is to provide an electrophotographic photoreceptor having a photosensitive layer containing a metal-free phthalocyanine as a carrier generating substance, by adding an electron-donating substance during the milling process of hot metal phthalocyanine. This is achieved by using metal-free phthalocyanine.

In the present invention, the electron-donating substance added in the process of milling α-type metal-free phthalocyanine is a nitrogen-containing cyclic compound, preferably a phenanthroline derivative, a bipyridine derivative, an indole derivative, a hensitriazole derivative, and a quinoline derivative. Consisting of one or more types selected from the group consisting of:

The milling treatment can be carried out using an appropriate milling device such as a homogenizer, using the α-type metal-free phthalocyanine and the electron-donating substance in the presence or absence of a dispersion medium. Wet mining using a dispersion medium is preferred. As the dispersion medium, water, -hydric or polyhydric alcohol, etc. can be used. The electron donating substance is preferably added at a ratio of 1 to xomIJ parts per 100 parts by weight of α-type metal-free phthalocyanine.

The treatment can be carried out at ambient temperature or at elevated temperature, and is sufficient within a few hours, preferably around 1 hour.

The thus obtained treated product is washed with water and dried to obtain a metal-free phthalocyanine powder. The obtained powder is then used as carrier generation*M in the production of a photoreceptor.

When a function-separated type electrophotographic window illuminator is constructed by using metal-free phthalocyanine that has been milled together with an electron-donating substance as a carrier generating material, it has a higher resistance compared to α-type metal-free phthalocyanine that is not subjected to such treatment. As a result, charging characteristics and photosensitivity are significantly improved. Although the mechanism by which such properties are improved by the addition of an electron-donating substance is not sufficiently clear, it is thought that the electron-donating substance improves the carrier generation ability and charge-accepting ability of the metal-free phthalocyanine. In addition, other milling processes that do not add such electron-donating substances, such as dry milling, require a processing time of 150 hours or more to obtain equivalent charging characteristics and improved photosensitivity. According to the present invention, the desired effect can be obtained in a very short treatment time of one hour.

Examples of the present invention will be described in detail below in connection with the production of a functionally separated photoreceptor.

〔Example〕

The metal-free phthalocyanine milled according to the present invention can be suitably used as a carrier-generating substance in a carrier-generating layer in a so-called functionally dispersed photoreceptor. Such a functionally dispersed photoreceptor has -a provided with a carrier transport layer on a conductive substrate, and further provided with a carrier generation layer thereon. Alternatively, on the contrary, a carrier generation layer may be provided on the conductive substrate, and a carrier transport layer may be provided thereon.

As the conductive substrate, metal plates or sheets made of aluminum, copper, zinc, etc., or plastic films such as polyester films, etc., on which these metals are attached are used. Particularly preferred is an aluminized polyester film.

The carrier generation layer is formed by applying a homogeneous mixture of a carrier generation substance, a binder resin, a solvent, etc., and drying the mixture. The carrier material is a metal-free phthalocyanine treated as described above. Known binder resins can be used, such as thermoplastic resins such as saturated polyester, polyamide, polysulfone, (meth)acrylic, and polycarbonate, and thermosetting resins such as epoxy, urethane, and silicone. Further, as the solvent, for example, an ether type 1g agent such as tetrahydrofuran, an aromatic hydrocarbon such as toluene, xylene, etc. are used.

Next, on the carrier generation layer formed as described above, a homogeneous mixture consisting of a carrier transport substance, the binder resin as described above, a solvent, etc. is applied and dried to form a carrier transport layer. As carrier transport substances, well-known ones such as aromatic tertiary amino and tertiary diamino compounds, polyvinylcarbazole compounds, pyrazoline derivatives, quinazoline derivatives, triazine derivatives,
Benzofuran 8R'L derivatives, oxadiazole derivatives, etc. can be used, particularly preferably 1-phenyl-3-<p-
diethylaminostyryl)-5-(p-diethylaminophenyl)-2-virapurine, p-diethylaminohenzaldehyde diphenylhydrazone, and the like are used.

In the functionally dispersed photoreceptor according to the present invention, the carrier generation layer may have a thickness of 0,000 to 10 μm, and the carrier transport layer may have a thickness of 5 to 100 μI.

Further, in the photoreceptor of the present invention, a carrier transport layer may be provided first, and a carrier generation layer may be provided thereon.

Example 1 First, 50 parts by weight of an aluminum-deposited polyester film having a thickness of 75 μm - diethylaminostyryl)-5- (p-diethylaminophenyl)-2-birapurine and 50 parts by weight of polymethyl methacrylate were added to 600 parts by weight of tetrahydrofuran.
A carrier transport layer was formed by applying a solution obtained by dissolving the heavy part so that the film thickness after drying would be 20 μm.

Next, a carrier generation layer was formed on the carrier transport layer thus formed in the following manner. First, α
Liquid 78, which was mixed at a ratio of 24 parts by weight of type-free metal phthalocyanine, 800 parts by weight of diethylene glycol, and 1 part by weight of phenanthroline, was subjected to wet milling treatment at 65°C for 1 hour using a homogenizer. After that, this /8? (l
was washed with water and dried to obtain a metal-free phthalocyanine powder. 5 parts by weight of the thus treated metal-free phthalocyanine powder, 10 parts by weight of Byron 200 (manufactured by Toyobo Co., Ltd.), and 140 ffi of tetrahydrofuran! The it part was mixed to obtain a uniform coating solution. This coating solution is applied onto the carrier transport layer formed on the aluminum-adsorbed polyester substrate using a wire bar so that the film thickness after drying is 1 μm to form a carrier generation layer, and the photoreceptor of the present invention is manufactured. Created.

Furthermore, as Comparative Example 1, a photoreceptor was produced in exactly the same manner as in Example 1, except that phenanthroline was not added during the wet milling process using homogenization.

The photoconductors of Example 1 and Comparative Example 1 produced as described above were tested using an electrostatic copying paper tester (manufactured by Kawaguchi Electric Co., Ltd., SP
-428) to perform corona discharge at +6KV for 10 seconds to charge the photoreceptor, measure the surface potential Vp (v),
After that, after leaving it in a dark place for 2 seconds, a wavelength of 790 nm, l
The time required for the surface potential of the photoreceptor to drop to 1/2 of V after being irradiated with light with an intensity of 1 m/-, that is, the half-attenuation exposure I
E + y□ (μJ 101+1) was measured. Table 1 shows the results of measuring the electrophotographic characteristics of each photoreceptor of Example 1 and Comparative Example 1 using this test device.

El/□ (μJ/1ffl) Example 1
631 1.2 Comparative Example 1 575 2.5 From Table 1, the photoreceptor of Example 1 has improved charging characteristics and photosensitivity compared to the photoreceptor of Comparative Example 1 to which phenanthroline was not added. It is recognized that In particular, the photosensitivity was 2.5 (μJ/crl) in Comparative Example 1.
On the other hand, Example 1 is 1.2 (μJ/-), which is 1/2
It has been reduced to the following values.

〔Effect of the invention〕

According to the present invention, by adding an electron-donating substance to α-type metal-free phthalocyanine, which is unsuitable as a photoreceptor as it is, and milling it, the charging characteristics and photosensitivity of the photoreceptor can be improved in a short time. Although the mechanism by which the charging characteristics and photosensitivity are improved by the addition of an electron-donating substance is not fully clear, it is thought that the carrier generation ability and charge-accepting ability of the metal-free phthalocyanine are improved by the electron-donating substance. Furthermore, whereas other milling processes that do not add electron-donating substances, such as dry milling processes, require a processing time of 150 hours or more to obtain equivalent charging characteristics and improved photosensitivity, the present invention The milling process in which an electron-donating substance is added according to the above has the advantage that equivalent charging characteristics and photosensitivity can be obtained in a very short processing time of about one hour.

Claims (1)

[Claims] 1) In an electrophotographic photoreceptor having a photosensitive layer containing a metal-free phthalocyanine, a metal-free phthalocyanine obtained by milling α-type metal-free phthalocyanine in the presence of an electron-donating substance is used. A photoreceptor for electrophotography characterized by the following. 2) In the electrophotographic photoreceptor according to claim 1, the electron donating substance is one or two selected from the group consisting of phenanthroline derivatives, bipyridine derivatives, indole derivatives, benzotriazole derivatives, and quinoline derivatives. An electrophotographic photoreceptor characterized by being a substance of more than one species.