JPS62296150A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body which has high sensitivity in a long wavelength region and is usable in a positive electric charge system by providing an electric charge transfer layer contg. an org. charge transfer material and a photosensitive layer formed by mixing and dispersing a prescribed org. electric charge generating material and the charge transfer material with and into a binder resin on a conductive substrate. CONSTITUTION:This electrophotographic sensitive body is formed by providing the charge transfer layer contg. the org. charge transfer material and the photosensitive layer formed by dispersing and mixing the org. charge generating material consisting of nonmetallic phthalocyanine which exhibits a strong peak at 6.7 deg., 8.7 deg., 15.1 deg., 17.7 deg., 23.8 deg., 26.1 deg., 27.4 deg., 30.0 deg. Bragg angle (2theta) in X-ray diffraction and the org. charge transfer material with and into a binder resin on the conductive substrate. The major axis of the particles of the nonmetallic phthalocyanine is 0.5-7.0mum and the ratio of the major axis/minor axis is 3-10. The deriv. of pyrazoline, hydrazone, triphenyl methane, etc., is used for the org. charge transfer material.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Technical Field to Which the Invention Pertains] The present invention relates to an organic material-based electrophotographic photoreceptor used in a positive charging system, and particularly relates to an electrophotographic photoreceptor that has high sensitivity in a long wavelength region. This invention relates to a photoreceptor for electrophotography.

[Prior art and its problems]

Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter simply referred to as photoreceptors) are inorganic photoconductive substances such as selenium or selenium alloys, inorganic photoconductive substances such as zinc oxide or cadmium sulfide, and binder resins. An organic photoconductive material such as polyvinyl anthracene, a phthalocyanine compound or a bisazo compound dispersed in a binder resin. Materials and vacuum-deposited materials are used.

The photoreceptor also has the ability to retain surface charge in the dark.

It is necessary to have the function of receiving light and generating charges, and also the function of receiving light and transporting charges, but the so-called tlL layer type photoreceptor, which has both these functions in one layer, is mainly used. There is a so-called laminated photoreceptor in which functionally separated layers are laminated, including a layer that contributes to charge generation and a layer that mainly contributes to surface charge retention in the dark and charge transport during light reception.

For example, the Carlson method is applied to image formation by electrophotography using these photoreceptors. Image formation in this method involves charging the photoconductor in a dark place by corona discharge, forming an electrostatic latent image of text or pictures on the document using light reflected from the document onto the surface of the charged photoconductor. This is done by developing the formed electrostatic latent image with toner, transferring the developed toner image to a support such as paper, and fixing the toner image to the support such as paper. After the toner image is transferred, the photoreceptor is After performing static neutralization, residual toner removal, optical static neutralization, etc., it is reused for heavy use.

In recent years, multilayer photoreceptors using organic materials have been put into practical use due to their advantages such as flexibility, thermal stability, and film formability. This type of laminated photoreceptor usually has a charge generation layer containing an organic charge transporting substance and a charge transporting layer containing an organic charge transporting substance laminated in sequence on a conductive substrate. Be taken. However, in negative corona discharge, a large amount of ozone is generated, so that the surface of the photoreceptor during charging is strongly oxidized by ozone. Therefore, it is necessary to take measures to prevent ozone deterioration by using the photoreceptor itself or the mechanism of the device. . On the other hand, with the positive charging method, positive corona discharge is more stable than negative corona discharge, and less ozone is generated.
Furthermore, it is convenient that it is easy to manufacture a compatible developing side, and the above-mentioned layer structure of the conductive substrate - charge generation layer - charge transport layer has an organic charge suitable for forming a photoreceptor to which a positive charging method can be applied. Transport substances and organic charge transporting substances have not yet been discovered.

Therefore, in order to obtain a photoreceptor that can be positively charged using currently available organic materials, a functionally separated type in which a charge generation layer is formed on a charge transport layer, or a charge transport material and a charge transport material are used. A single-layer type photoreceptor in which the photoreceptors are mixed to form a single photoreceptor layer has been considered.

However, in the former functionally separated type, when forming the charge generation layer on the charge transport layer, the charge generation layer is formed with a thickness of 1 μm or less, preferably 0.3 μm or less, and without altering the charge transport layer. This is a particularly difficult problem with coating methods. Furthermore, the vapor deposition method has the disadvantage that it is difficult and expensive to manufacture because it requires vapor deposition.

On the other hand, the latter single-layer type has the disadvantages of low surface potential and insufficient repeatability.In order to solve these disadvantages of the single-layer type, Japanese Patent Application Laid-Open No. 116754/1983 A method is disclosed in which two to three or more phthalocyanine compound photoconductive layers are provided and the crystal forms or metals of the phthalocyanine between the layers are made different. However, the improvement in surface potential, which is a drawback of single layer, has not yet been observed.

Further, JP-A-59-151!58 discloses a method in which a disazo pigment and a sensitizer are added to a phthalocyanine compound photoconductive layer, but this method has the disadvantage that the sensitivity is somewhat inferior.

Further, although the two-layered ball mill pulverized metal-free phthalocyanine proposed by the present inventors has improved stability during continuous repeated use, it is still not fully satisfactory in terms of sensitivity.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide an electrophotographic photoreceptor that has high sensitivity in a long wavelength range and can be used in a positive charging system.

[Key points of the invention]

An object of the present invention is to provide an electrophotographic photoreceptor comprising a photosensitive layer in which a charge transport layer, a charge transport material, and a charge transport material are mixed and dispersed in a binder resin on a conductive substrate, and in which An X-ray diffraction diagram of metal-free phthalocyanine, which is a charge transport material, shows Brangg angles (2θ) of 67°, 8.7°, and 15.
．． 1°, 17.7°, 23.8".

Metal-free phthalocyanine (according to the first invention) showing clear strong peaks at 26.1', 27.4°, and 30.0°, also Bragg angle (2θ) in the X-ray diffraction diagram
6.7°, 7.2°, 13.4°, 14.5°, 1
5.2°, 16.0°.

20.2°, 21.7°, 24. Oo, 24.8°,
26.6°.

Metal-free phthalocyanine (
According to the second invention), the metal-free phthalocyanine particles have a long sleeve diameter of 0.5 μm or more and 7.0 μm or less, and a ratio of major axis diameter/minor axis diameter of 3 or more and 10 or less. This is achieved by using

[Embodiments of the invention]

FIGS. 4, 2, and 3 are X-ray diffraction patterns of the α-type metal-free phthalocyanine, the metal-free phthalocyanine according to the first invention, and the metal-free phthalocyanine according to the second invention, respectively (
Cu-Ka). The metal-free phthalocyanine, which is a preferred GL of the present invention, has the following characteristic X-ray diffraction pattern.

The metal-free phthalocyanine according to the first invention has a Bragg angle (2θ) of 6.7°, 8.7°,! 5.1°, 17
．． 7°.

It shows distinct strong peaks at 23.3°, 26.1°, 27.4°, and 30.0°, and when compared with those of other crystal forms, there are clear differences from the α and β forms. , X type.

It is different from known crystal forms such as γ type and η type.

The metal-free phthalocyanine according to the 20th invention has a Bragg angle (2θ) of 6.7°, 7.2°, 13.4°, 1
4.5°.

15.2°, 16.0°, 20.2°, 21.7°
, 24.0°.

Clear strong e- at 24.8°, 26.6°, 27.3°
When compared with other crystal forms, it is partially similar to the α-form, but has clear differences from the β-form.
It is different from known crystal forms such as X type, γ type, and η type.

Furthermore, those in which acicular particles are seen in the above two types of crystal forms,
In detail, as shown in Figure 65, if a rectangle is made with the minimum area in contact with the particles, and the length of the long side is defined as the long sleeve diameter b1, and the length of the short side is defined as the short axis diameter a, then the long sleeve diameter is is 0.5μ
Those characterized by having a length of m or more and 7.0 μm or less and a ratio of long sleeve diameter b/short axis diameter a of 3 or more and 10 or less exhibit excellent electrophotographic properties. Examples are shown below.

FIG. 1 is a conceptual cross-sectional view showing one embodiment of the photoreceptor of the present invention, in which 1 is a conductive substrate, 2 is a charge transport layer, and 3 is a photosensitive layer.

The conductive substrate 1 acts as an electrode for the photoreceptor and at the same time serves as a support for the other two 1, and has a film-like shape.
It may be plate-shaped or cylindrical, and the material may be metal such as aluminum, stainless copper, glass,
It may also be made of ceramic, resin, etc. whose surface is subjected to conductive treatment.

The charge transport layer 2 is made by dispersing an organic charge transport substance in a binder resin, and serves as an insulating layer in the dark, contributing to retaining the surface charge of the photoreceptor, and when receiving light, is injected from the photoreceptor layer 3. It exhibits the function of transporting electric charges.

The photosensitive layer 3 is a layer formed by dispersing an organic charge transport substance in a binder resin, and has the function of receiving light and generating electric charge, and at the same time has the function of transporting the generated electric charge. are doing.

Charge transport M2. Photosensitivity As the organic charge transport substance used for photosensitization, derivatives such as pyrazoline, hydrazone, triphenylmethane, and oxadiazole can be considered. In addition, as the binder (sealant), all general binder resins such as thermoplastic or thermosetting resins that have electrical insulation and film-forming properties can be used. Examples of suitable binder resins are: , this 1 = saturated polyester l!, thermoplastic binder resins such as, but not limited to, polyamide resins, acrylic resins, polycarbonate resins, ethylene-vinyl acetate polymers, vinyl chloride, cellulose esters, Epoquin Thermosetting binder resins such as resins, urethane resins, silicone resins, phenolic resins, and thermosetting acrylics (sealants).

The thickness of the charge transport layer 2 must be 3. in order to maintain a practically effective surface potential. The range is preferably 30 μm, more preferably 5 μm to 20 μm. Further, the film thickness of the photosensitive layer 3 is 0.
The range is preferably 5 to 10 μm, more preferably 1 to 5 μm.
It is m. If the film thickness of the photosensitive layer 3 is less than 0.5 μm, there are manufacturing problems such as poor photosensitivity and difficulty in forming such a thin film, and if the film thickness is more than 10 μm, the surface potential becomes low, making it impractical for practical use. It becomes irrelevant.

As a layer structure of the photoreceptor of the present invention, a coating layer may be formed on the photosensitive layer. The thickness of the coating layer is preferably <0.01 to 3 μm as long as it can change the surface properties. If the thickness of the coating layer is too thin (less than 0.01 μm), no improvement in charge-accepting ability, that is, surface potential, or improvement in printing durability can be expected. is undesirable because it increases The coating layer is formed by a coating method or a vapor phase method depending on the photosensitive layer to be coated, and the coating material should be as transparent as possible in the wavelength region where the light absorption of the charge transport substance contained in the photosensitive layer is maximum. desirable.

Specific examples will be described below.

[Example 1. ] (Regarding the first invention) First, an X-ray diffraction diagram (Cu-Ka) as shown in FIG.
Starting material is α-type gold-free phthalocyanine having 2
Between two linear motors placed facing each other, α-type metal-free phthalocyanine and a non-magnetic case containing a Teflon piece as a working piece are passed through and crushed.Ll! JMAC(Li
Near induction! Jator Mi
xing and crushing (manufactured by Fuji Electric) for 20 minutes to form a fine powder. 1 part by weight of this finely powdered sample and 50 parts by weight of DMF (N, N'-dimethylformamide) solvent were subjected to ultrasonic dispersion treatment for 1 hour using an ultrasonic homogenizer. Thereafter, the sample and DMF were separated, filtered, and dried to obtain the target sample. FIG. 2 is an X-ray diffraction diagram of the sample after such treatment. From the X-ray diffraction diagram of the α-type metal-free phthalocyanine shown in FIG. 2, it can be seen that the crystals have clearly changed due to the above treatment.

Further, when observed with a scanning electron microscope (SE!J), acicular particles were observed, with a major axis diameter bo of 5 μm or more and 7 μm or less, and a ratio of major axis diameter b/minor axis diameter a of 3 or more and 10 It can be seen that it is within the following range.

Next, the charge transport substance 1-phenyl-3-(P-diethylaminostyryl)-5-(para-diethylaminophenyl)
A solution prepared by dissolving 100 parts by weight of -2-pyrazoline (ASPP: manufactured by Anan Drinks Co., Ltd.) in 700 parts by weight of tetrahydrofuran (THF) and polymethyl methacrylate polymer (PMMA)
A coating solution prepared by mixing 100 parts by weight of (manufactured by Tokyo Kasei) dissolved in 700 parts by weight of toluene is applied onto an aluminum-deposited polyester film substrate using a wire bar, resulting in a film thickness of 102 m after drying. A charge transport store was formed. 50 parts by weight of each of the above-treated metal-free phthalocyanines and ASPP were added to the charge transport layer thus obtained.
100 parts by weight of polynystyl resin (trade name: Vylon 20)
A coating solution was prepared by kneading 100 parts by weight (manufactured by Toyobo Co., Ltd.) and a THF solvent for 3 hours in a mixer, and then applied with a wire bar to form a single-layer photosensitive layer so that the film thickness after drying was 2 μl. A photoreceptor was prepared.

[Example 2] (According to the second invention) In the same manner as in Example 1, the α-type metal-free phthalocyanine shown in FIG. 1 is subjected to a dry process for pulverization.

The sample pulverized by this treatment was treated in the same manner as in Example 1, except that the zero liver solvent in Example 1 was replaced with a DEG (diethylene glycol) solvent. Thereafter, the sample and DEG were separated, filtered, and dried to obtain a target sample. FIG. 3 shows an X-ray diffraction diagram of the sample after such treatment. From FIG. 3, there are some parts that are similar to the X-ray diffraction diagram of the α-type metal-free phthalocyanine shown in FIG. 4 and the X-ray diffraction diagram of the one according to the first invention shown in FIG. Peaks and the like appear, indicating that the crystals have clearly changed due to the above treatment. As a result of observation by SEM, the particle diameter was the same as in Example 1, with the major axis diameter b0.
The ratio of major axis diameter b/minor axis diameter a was in the range of 5 μm or more and 7 μm or less, and 3 or more and 1O or less.

Subsequently, a photoreceptor was produced by the same process as in Example 1.

[Comparative Example 1] Metal-free phthalocyanine was once dissolved in sulfuric acid at 5°C or lower,
The metal-free phthalocyanine, which was poured into ice water and reprecipitated and subjected to the same DEG treatment as in Example 2, shows the same X-ray diffraction peak as in Example 2.

entrustment). When observed using Example 1, the acicular particles observed in Examples 1 and 2 were not observed. A photoreceptor was produced in accordance with Example 1, except that this metal-free phthalocyanine was used as the charge transport material.

[Comparative Example 2] A photoreceptor was produced according to Example 1, except that metal-free phthalocyanine that had been pulverized in a ball mill for 150 hours was used as the charge transport material.

The electrophotographic characteristics of the cough photoreceptors produced in Example 1.2 and Comparative Example 1.2 were measured using Kawaguchi Electric's electrostatic recording paper test mounting rSP-4.
Measured using 28J. The surface potential Vs (volts) of the photoreceptor is +6. (This is the initial surface potential when corona discharge of lkV is performed for 10 seconds to positively charge the surface of the photoreceptor, and then the surface potential is Vd (volts) when the corona discharge is stopped and the surface is kept in the dark for 2 seconds. Then, when the surface of the photoconductor is irradiated with lkV 790r+m wavelength light, the time (seconds) until the surface potential becomes half of Vd is determined, and the residue is half-attenuated by multiplying that time by the light intensity of 1 μW. The exposure amount E'A (μJ/cIIl) was defined as the residual potential Vr (volts).The surface potential when the surface of the photoreceptor was irradiated with 1 μW of 7901 m wavelength light for 10 seconds was defined as the residual potential Vr (volts). It is shown in Table 1.

Table 1 As shown in Table 1, Examples 1 and 2 were 79% lower than Comparative Examples 1 and 2 even in the positive charging method.
It can be seen that the photoreceptor exhibits extremely high sensitivity and excellent electrophotographic properties in the long wavelength light region of 0 nm.

[Example 3 and Example 4] In place of each of the charge transport layers of Example 1 and Example 2, P-diethylaminobenzaldehyde-diphenylhydrazone (ABPH: 60 parts by weight of Asanan I!), polyester (sealing (Product name Byron 200: manufactured by Toyobo) 4
The procedure was carried out according to Example 1, except that a coating liquid consisting of 0 parts by weight and 1400 parts by weight of tHF was coated with a wire bar onto an aluminum-deposited polyester film substrate so that the film thickness after drying was 10 μm to form a charge transport layer. Example 3 and Example 4
A photoreceptor was fabricated. Example 1 about these photoreceptors
The electrophotographic properties were measured under the same conditions. The result is the second
Shown in the table.

As seen in Table 2, it can be seen that the photoreceptor has a sufficiently high surface potential and exhibits highly sensitive characteristics.

〔Effect of the invention〕

According to the present invention, the α-type metal-free phthalocyanine is L l
> Dry treatment such as AMAC, followed by wet treatment with a solvent such as DEC, to improve the Bragg angle (
2θ) 6.7°, 7.2°, 13.4°,
14.5°, 15.2°.

16.0°, 20.2', 21.7°124.0°
, 24.8°.

Metal-free phthalocyanine with strong peaks at 26.6°, 27.3° and 6.7°, 8.7°, 15.1°,
17.7°.

238°, 26.1°, 27.4°, 30. (Gold-free phthalocyanine with a strong peak at 1° is obtained.

A photoreceptor using such metal-free phthalocyanine as the photosensitive layer has significantly improved photosensitivity in the long wavelength range compared to a photoreceptor using dry-processed (ball milled, etc.) metal-free phthalocyanine as the photosensitive layer. I was able to do that. Furthermore, among the metal-free phthalocyanines having the above-mentioned X-ray diffraction peaks, those with acicular particles have similar x'8 diffraction peaks, and in longer wavelength ranges than those without acicular particles. It was possible to significantly improve the photosensitivity of . Therefore, a positively charged photoreceptor having high sensitivity in the oscillation wavelength range of a semiconductor laser can be obtained, and can be effectively used in a semiconductor laser printer.

[Brief explanation of drawings]

FIG. 1 is a conceptual cross-sectional view showing an example of a photoreceptor box according to the present invention. Figures 4, 2 and 3 are X-ray diffraction diagrams of α-type metal-free phthalocyanine and metal-free phthalocyanine according to the first and second inventions, respectively, and Figure 5 is a diagram showing the definition of particle shape. It is. 1 conductive substrate, 2 charge transport layer, 3 photosensitive layer. Figure 1? θ Figure 2 2θ Figure 3 2θ Figure 4 Series 5

Claims (1)

[Claims] 1) A charge transport layer containing an organic charge transport substance on a conductive substrate and a Bragg angle (2θ) of 6.7° in X-ray diffraction.
, 8.7°, 15.1°, 17.7°, 23.8°, 2
A photosensitive layer is provided in which an organic charge-generating substance made of metal-free phthalocyanine and an organic charge-transporting substance, which exhibit strong peaks at 6.1°, 27.4°, and 30.0°, are mixed and dispersed in a binder resin. The electrophotographic photoreceptor is characterized in that the major axis diameter of the metal-free phthalocyanine particles is 0.5 μm or more and 7.0 μm or less, and the ratio of major axis diameter/minor axis diameter is 3 or more and 10 or less. Photoreceptor for electrophotography. 2) A charge transport layer containing an organic charge transport substance on a conductive substrate and a Bragg angle (2θ) of 6.7° in X-ray diffraction.
, 7.2°, 13.4°, 14.5°, 15.2°, 1
6.0°, 20.2°, 21.7°, 24.0°, 24
．． Electrophotography comprising a photosensitive layer in which an organic charge-generating substance made of metal-free phthalocyanine and an organic charge-transporting substance showing strong peaks at 8°, 26.6°, and 27.3° are mixed and dispersed in a binder resin. Electrophotographic photoreceptor, characterized in that the major axis diameter of the metal-free phthalocyanine particles is 0.5 μm or more and 7.0 μm or less, and the ratio of major axis diameter/minor axis diameter is 3 or more and 10 or less. Photoreceptor for use.