JPS6292964A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having a high electrostatic charge potential and a good repeating stability by incorporating a brominated anthanthrone having a prescribed crystallinity to a photosensitive layer. CONSTITUTION:The brominated anthanthrone pigment shown by the formula is incorporated to the photosensitive layer which is obtd. by laminating a carrier transfer layer and a carrier generating layer on a conductive substrate. The brominated anthanthrone pigment is obtd. by pulverizing said pigment which has a small density in a crystalline defect and satisfys the formula 0.2<S1/S2<=1.0, when diffraction strengths are each S1 and S2 in a X ray diffraction spectrum (2theta=18.4 deg. and 26.7 deg.) to form the particles (preferably <=2mum particle size). To obtain the prescribed pigment particle, the crude material of said pigment is treated with a non-ionic org. solvent such as monochlorobenzene, nitrobenzene and beta-naphthol, etc., and the obtd. crystal is aged and then washed, filtered and separated to obtain the brominated anthanthrone pigment having the high crystallinity.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a photoreceptor, particularly an electrophotographic photoreceptor.

Conventional technology Generally, substances that absorb visible light and generate carriers are
It is difficult to form a film by itself with the exception of a very small number of materials such as amorphous selenium, and the problem is that they have a poor ability to retain electric charges applied to their surfaces. On the contrary, materials that have excellent film-forming ability and can retain a charge of 500 V or more for a long time with a thickness of about 10 μm generally have the disadvantage of not having sufficient photoconductivity due to absorption of visible light. have.

For this reason, as shown in FIG. 3, a carrier generation layer 2 containing a substance that absorbs visible light and generates charge carriers is provided on a conductive substrate 1 such as A1 via a subbing layer 5. It has been proposed that a carrier transport layer 3 for transporting either positive or negative charge carriers generated in the carrier generation layer or both is further provided to form a laminate 4, and that this laminate constitutes a photosensitive layer. By assigning the generation and transport of these charge carriers to separate materials, a wide range of materials can be selected to meet the requirements of the electrophotographic process, such as charge retention, surface strength, and resistance to visible light. It has become possible to improve or improve sensitivity, stability during repeated use, etc.

Note that in FIG. 3A, the carrier generation layer 2 may be provided on the carrier transport layer 3.

In such photoreceptors, it is known to use a brominated anthanthrone pigment as a high-grade organic pigment in the photosensitive layer, particularly in the carrier generation layer. This pigment has higher sensitivity than conventional inorganic particles or perylene pigments,
A uniform photosensitive layer with good scratch resistance can be obtained.

However, in order to use this pigment as an electrophotographic photoreceptor, it is necessary to improve both its crystallinity and purity, and the sublimation purification method is effective in achieving this.

However, the present inventor has investigated and found that in the case of conventional methods, the shear stress (Share stress) applied to the pigment is
5tress) is large (when the substrate temperature is high and the pigment particles are large and highly crystalline), the crystal lattice is likely to be distorted or impurities may easily enter from the dispersion container. For this reason, charging ability and sensitivity tend to decrease, and the amount of repeated potential decrease tends to increase.

Conversely, if the shear stress applied to the pigment is small (in this case, the substrate temperature is low and the pigment particles are small and have low crystallinity),
The electrophotographic properties deteriorate and are unsuitable.

C.2 Purpose of the Invention An object of the present invention is to provide a photoreceptor that exhibits a high charging potential and has good repeat stability.

An anth anthrone pigment is contained in the photosensitive layer, and the X-ray diffraction spectrum of the brominated anth anthrone pigment is
When the diffraction intensities at =18.4° and 26.7° are respectively S (18,4°) and S (26,7-), 0.2 ≦S (18,4°) /S (26,7 °
)≦1.0.

Structural formula: In the process of arriving at the present invention, the present inventor discovered that the pulverization (shear stress) of pigments as described above increases the crystal defect density and deteriorates the properties, and that this crystal defect density can be reduced by the above-mentioned bromination. It has been found that there is a strong correlation with the diffraction intensity ratio at diffraction angles of 2θ-18, 4° and 26.7° in the unique X-ray diffraction spectrum of the Ansuanthrone pigment. That is, the diffraction intensity ratio: S (1B, 4°)/S (26,7°) is 0.
．． The above object of the present invention can be achieved by setting the value to 2 to 1.0. As shown in Figure 1, this intensity ratio is based on the particle size of the pigment after pulverization of 6 μm or less (the practical particle size is 2 μm or less).
This can be achieved by controlling the
The lower limit should be set at 0.2 because if it is less than 0.2, it will be easier to become amorphous. In addition, it is further desirable that this intensity ratio be 0.3 to 0.8.

In this way, by regulating the pigment pulverization and dispersion time based on the diffraction intensity ratio, good results can be obtained as described below.

In the present invention, an attempt was made to produce a brominated anthanthrone pigment using the following method.

That is, anthanthrone shown by the following structural formula is brominated in sulfuric acid, drained, and separated by filtration to obtain brominated anthanthrone having the same structural formula as that used in the present invention.
This was washed and dried.

However, in this case, only amorphous, non-crystalline particles are obtained. Moreover, when the degree of bromination is increased, 2θ=18.4°
The peak at 0 disappears, and Δθ (26, 7°) becomes large.

However, the crude raw material containing the sample brominated by the above method as a main component is treated with a nonionic organic solvent (preferably, After treatment with a borderline solvent (a mixture of this organic solvent and an ionic solvent consisting of an acid such as H2SO4 or an alkali such as NaOH) to ripen the crystals, washing and separating by filtration, highly crystalline brominated It has been found that an anth anthrone pigment can be obtained. This pigment is highly crystalline and can be obtained with high purity.
It was found that it is very suitable for use in photoreceptors, exhibiting high charging potential, sensitivity, and good repetition stability.

It has also been found that by using such a so-called chemical refining method, a clean crystalline purified product can be obtained from an amorphous raw material. Further, when this chemical purification method is used, the pigment does not decompose, there is no corrosion due to removal of Br, and the target product can be obtained in good yield.

Note that the pigment according to the present invention can be produced not only by the above chemical purification method but also by other methods (for example, sublimation purification method).

The average particle diameter of the brominated anthrone pigment particles (herein, means the average value of the long axis length) is 2 μm.
The following is desirable. By beating to make the particles fine to 2 μm or less, it is possible to prevent the influence of the particle size on the surface of the photoreceptor, to smooth the surface of the photoreceptor, and to stabilize the pigment dispersion. When the average particle size exceeds 2 μm, convex portions are likely to form on the surface, but when the average particle size is 2 μm or less, such convex portions can be virtually eliminated and a flat surface can be achieved, and the sedimentation of particles in the dispersion can be reduced, making it easier to form liquids. can be stabilized. As a result, it is possible to obtain a photoreceptor that does not suffer from discharge breakdown or toner filming. The average particle size of the pigment is preferably 2 μm or less, more preferably 1 μm or less, and 0.
．． More preferably, the thickness is 5 μm or less. However, if the average grain size is too small, crystal defects will increase and the repeatability will deteriorate, and there will be a limit to miniaturization, so it is desirable to set the lower limit of the average grain size to 0.01 μm.

Examples of binder resins that can be used in the photoreceptor of the present invention include polyethylene, polypropylene, acrylic resin, methacrylic resin, vinyl chloride + M JAM, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, and alkyd resin. , addition polymerization type resins such as polycarbonate resins, silicone resins, melamine resins, polyaddition type resins, polycondensation type resins, and copolymer resins containing two or more of the repeating units of these resins, such as vinyl chloride-acetic acid. Examples include vinyl copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and the like. However, the binder resin is not limited to these, and all resins commonly used for such purposes can be used.

Carrier transport substances used in the carrier transport layer in the present invention include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidasilone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, pyrazoline derivatives, Oxacilone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives,
Phenazine derivatives, aminostilbene derivatives, hydrazone derivatives, biphenylamine derivatives, triphenylamine derivatives, poly-N-vinylcarbazole, poly-1-
Vinylpyrene, poly-9-vinylanthracene, 2.4
．． 7-) Linitrofluorenone, 2,4,5.7-titranitrofluorenone, 2,7-sinitrofluorenone, and the like.

Further, examples of organic solvents used for forming the photosensitive layer of the present invention include methylene chloride, methylene bromide,
Single solvents such as 1.2-dichloroethane, sym-tetrachloroethane, cis-1,2-dichloroethylene, 112-)dichloroethane, chloroform, bromoform, dioxane, tetrahydrofuran, pyridine, etc., or various mixed solvents containing these as main components can be mentioned.

E, Example Embodiments of the present invention will be described in detail below with reference to the drawings.

Fuko - Example 1 - After brominating Anse Anse Lcon in sulfuric acid, 50 g of brominated Anse Anthrone fine powder obtained by draining the water was mixed with 100 m6 of nitrobenzene and 42 mm of H2S O. After stirring slowly at 100°C for 24 hours, the mixture was left to cool.
48.3 g of highly crystalline brominated anthinthrone pigment was obtained. X-ray diffraction spectrum of purified pigment (JEOL J
DXIORA CuK! 1.541 is shown in Figure 2.

The obtained purified pigment 40 [was filled into a porcelain Beau Lumille,
The material was crushed for 24 hours at 20 rotations per minute (the critical rotation speed for giving the maximum crushing energy was 70 rotations).

Next, polycarbonate resin [Panlite ■, -125
A solution of 20 g of 0J (manufactured by Kijin Kasei Co., Ltd.) dissolved in 1,300 m of 1,2-dichloroethane was added and dispersed for 24 hours to obtain a coating solution for forming a carrier generation layer.

The pigment was separated by filtration using - part of the obtained coating solution, and
Table 1 shows the results of measuring the intensities at 2θ-18, 4° and 26.7° of the line diffraction spectrum. Table 1 also shows the average value of the major axis/minor axis ratio of the purified pigment and the coating liquid face 11 after pulverization and dispersion [7 stones and the average value of the major axis - 17].

Actual difference example-I The procedure was carried out in the same manner as in Example 1 except that the milling time in Example 1 was changed to 12 hours. person) did.

Example ↓ Example 17 was repeated except that the grinding time was 6 hours and 17 hours.

Comparison Example 49. ? The procedure was the same as in Example 1 except that the grinding time was 120 hours.

Comparative Example J The same procedure as in Example 1 was carried out except that the raw materials used in Example 1 which were not subjected to crystallization treatment were dispersed for 24 hours without being crushed.
The coating solution for forming a carrier generation layer was prepared using the coating solution for forming a carrier generation layer obtained in the Examples and Comparative Examples described in Table 7-1. It was created.

1 on the 100φ aluminum drum, 0.1 dry smoke old light!
3/n? of chloride, ru-vinyl acetate, ':' ru-anhydrous 7
1. / Inic acid copolymer Kikawa 3 ""f, Suretsuk MFiO
-1 (manufactured by Block Chemical Industry Co., Ltd.) was provided by dip coating, and then the carrier generation layer forming coating solution was applied to the intermediate layer by dip coating, so that the dry weight was 2.1 g. A carrier generation layer of /' resistance was obtained.

On the other hand, the gear carrier transport substance CH3 2,4,6-dolinitro 1-ri1'J rubenzene O, which is represented by the following structural formula,
2251? ,, Polycarbonate 1/Resin 3001ζ Sold 1
, 2-dichloroethane'2000m, liter volume PIJl
The carrier-generated JEi is coated with the coating liquid for forming the ceria transport layer by dip coating.
''-: (rT,, coating?ii'!,-(:,.Dry weight'' is 19 g/'n?) Formation of carrier transport layer (51
1,2 - ζ Electrophotographic photoreceptor of the present invention and Takashi (Third
Note that instead of the above, the key/rear transport j- may be formed first, and then the carrier generation layer may be formed thereon (Fig. 3B) Above Examples The samples obtained in the above and comparative examples and the comparative samples were mounted on a photoconductor testing machine (Konishi Roku Photo Industry Momme), and a surface potential needle "Electrostatic Voltmeter 144D-LD" was used.
The exposure amount E7 required to reduce the charge potential vo (V) and the surface potential from -600V to -100V using a mold (manufactured by Monroe Electronics Inc.)
(j2 x -5ec) and the surface potential is -600■
The potential retention rate DD (%) after 5 seconds was examined.

Further, the test was repeated 5,000 times to examine the stability of the charging potential.

For samples whose charging potential was less than 600 cm, the charging current was increased by more than the standard value and 86g3 and DD were measured.

The results are shown in Table 2 (sample fish in Table 2 correspond to the example fish and comparative example fish in Table 1).

Table 2 From Tables 1 and 2, it can be seen that the samples according to the present invention have good sensitivity and potential holding performance.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIG. 1 is an example of a graph showing the X-ray diffraction intensity ratio depending on the particle size of the pigment, and FIG. The spectrum diagram, FIGS. 3A and 3B are cross-sectional views of the electrophotographic photoreceptor. In addition, in the reference numerals shown in the drawings, 1... Conductive substrate 2... Carrier generation layer 3... Carrier transport layer.

Claims (1)

[Scope of Claims] 1. A brominated anthanthrone pigment represented by the following structural formula is contained in the photosensitive layer, and the X-ray diffraction spectrum of the brominated anthanthrone pigment has 2θ=18.4° and 2
When the diffraction intensity at 6.7° is S (18.4°) and S (26.7°), 0.2≦S(18.4°
)/S(26.7°)≦1.0. Structural formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼