JPS6295536A - Photosensitive body - Google Patents

Abstract

PURPOSE:To improve the sensitivity, environmental stability, residual potential characteristics and durability by using specified brominated anthanthrone as a carrier generating substance and a specified amine compound as a carrier transferring substance. CONSTITUTION:Brominated anthanthrone represented by formula I is used as a carrier generating substance and an amine compound represented by formula II is used as a carrier transferring substance. In the formula II, R1 is a bivalent aromatic or heterocyclic group and each of R2-R5 is H, halogen, 1-4C alkyl or 1-4C alkoxy. When a photosensitive body is negatively charged, the amount of the carrier generating substance used is 0-100wt% of the amount of a binder and the amount of the carrier transferring substance is 10-500wt%. When a photosensitive body is positively charged the carrier generating substance is preferably used by 10-300pts.wt. per 100pts.wt. resin binder. Thus, the resulting photosensitive body has high sensitivity and potential retentivity, undergoes little deterioration by fatigue even after repeated use and little reduction in the sensitivity even at low temp. and also has superior potential stability.

Description

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

In prior art-i, 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, it has excellent film forming ability,
In addition, materials that can retain a charge of 500 V or more for a long time with a thickness of about 10 μm generally have the disadvantage that they do not have sufficient original thickness conductivity due to absorption of visible light.

For this reason, as shown in FIG. 4A, a carrier generation layer 2 containing a substance that absorbs visible light and generates charge carriers is formed on a conductive substrate 1 such as Heβ through an underlayer 5. It has been proposed to provide a laminate 4 by further providing a carrier transport layer 3 for transporting either positive or negative charged carriers generated in the carrier generation layer or both, and to construct a photosensitive layer by this laminate. In this way, by assigning charge carrier generation and transport to separate materials, a wide range of materials can be selected and the material properties required in the electrophotographic process, such as charge retention, surface strength, and resistance to visible light, can be improved. It has become possible to improve or improve sensitivity, stability during repeated use, etc.

Note that in FIG. 4A, the carrier generation layer 2 may be provided on the carrier transport layer 3 as shown in FIG. 4B.

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, and can provide a uniform photosensitive layer with good scratch resistance.

However, in order to use this pigment as an electrophotographic photoreceptor, it is not enough to select the above-mentioned brominated anthurone as a carrier-generating substance.1. It is necessary to select an effective carrier transport substance,
No effective carrier transport material has been proposed yet.

C2 Purpose of the Invention The purpose of the present invention is to improve the characteristics of a photoreceptor, especially its sensitivity, its environmental stability, residual potential characteristics, and durability by selecting specific carrier-generating substances and carrier-transporting substances. It's about improving.

21 Structure of the invention and its effects, that is, the present invention uses a brominated anthurone represented by the following structural formula as a carrier-generating substance, and an amine-based compound represented by the following general formula as a carrier-transporting substance. This is related to the photoreceptor used in the photoreceptor.

Structural formula: (However, in this general formula, R2 represents a divalent aromatic group or a heterocyclic group. R3 includes an arylene group, an arylene arylene group, a carbazole residue, etc., and the arylene group includes An example is a biphenyl group. Among these, an arylene arylene group, particularly a biphenyl group, is preferred.

Rz, R3, R4 and R3 are different from each other or the same group, and represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. ) According to the present invention, the brominated anthurone of the above structural formula has high sensitivity and good durable clutch properties, and the carrier transport substance of the above general formula used has excellent solubility in the binder resin, It exhibits high sensitivity, low photofatigue resistance, and low residual potential.

Therefore, the combination of carrier-generating substance and carrier-transporting substance according to the present invention can improve the properties of a photoreceptor.

The brominated anthurone used in the present invention undergoes a pulverization process during its manufacturing process, but such pulverization (shear stress) increases its crystal defect density and deteriorates its properties.
This crystal defect density is determined by the half-width of the diffraction intensity at diffraction angles 2θ-18, 4° and 26.7° of the specific X-ray diffraction spectrum of the above-mentioned brominated anth-anthrone pigment (i.e., the peak width of the diffraction intensity spectrum). Spectral width at an intensity of 172) Δ
It is known that there is a close relationship with θ. Figure 5 shows the spectrum of the brominated anthurone pigment obtained by the conventional sublimation purification method, but when it is ground in a ball mill, the peak at 2θ = 18.4° is blunted and Δθ (18,4') and Δθ(26,7°) become large. These Δθ become larger depending on the grinding time as described later.

On the other hand, an attempt was made to produce a brominated anthanthrone pigment by the following method.

That is, anthanthrone shown by the following structural formula is brominated in sulfuric acid, drained with water, filtered and separated 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, Δθ becomes too thick, and only amorphous, non-crystalline particles are obtained. Also, as the degree of bromination is increased, the peak at 2θ-18,4° disappears, and Δθ becomes too thick.
θ (26,7°) becomes large.

However, the crude raw material containing the brominated sample as a main component by the above method is treated with a nonionic organic solvent selected from monochlorobenzene, nitrobenzene, β-naphthol, 1-chloronaphthalene, etc. (preferably, this (Borderline solvent, which is a mixture of an organic solvent and an ionic solvent consisting of an acid such as HasO or an alkali such as NaOH)
It has been found that a highly crystalline brominated anth-anthrone pigment can be obtained by treating it with water to form crystals (W), washing it, and separating it by filtration and excitation. This pigment was found to be highly crystalline and highly pure, exhibiting high charging potential, high sensitivity, and good repeat stability, making it very suitable for use in photoreceptors. Figure 1 shows the case where the mixed solvent of the nonionic organic solvent and acid is used, Figure 2 shows the case where the mixed solvent of the nonionic aqueous solvent and alkali is used, and Figure 3 shows the case where the mixed solvent of the nonionic organic solvent and the alkali is used. The spectra obtained when ionic organic solvents are used are shown, and it can be seen that the half-width Δθ is small and the peaks are large, that is, the crystallinity and purity are good (particularly in Figures 1 and 2). A good example is ).

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-mentioned chemical purification method but also by other methods. For example, by the sublimation purification method, the half width Δθ (18,4°) is 0.
．． It is possible to obtain a pigment whose Δθ (26,7°) is 1° or less when the angle is 8° or less.

The brominated anthanthrone pigment obtained by the chemical purification method described above is actually pulverized and dispersed to obtain a desired particle size. At this time, Δθ changes depending on the grinding time, and in particular, depending on the selection of the grinding time, (Δθ (18, 4°) ≦ 0
．． 8°) and/or (Δθ (26,7°)≦1°). With this half-width range,
As is clear from the data described below, the crystal defect density of the pigment particles is reduced, and the electrophotographic properties are greatly improved.

Regarding the particle shape of the brominated anth-anthrone pigment, if the short axis length is a and the long axis length is b, then b/a
It is desirable that ≧1.1. That is, it was found that excellent characteristics could be obtained by this ratio. However, as the grain size becomes finer, not only does Δθ improve, but also the strength (absolute value) decreases, so even if Δθ≦1° is satisfied, sufficient crystallinity may not be obtained. In other words, Δθ≦1°
However, if b/a<1.1, the crystallinity of the particles tends to decrease, so if b/a≧1.1, or even 1.1≦b
It is effective to set /a≦20. Also, 1.5
It is even better that ≦b/a≦15.

Here, the long axis length b indicates the length of the axis (long axis) having the longest distance in an arbitrarily selected crystal in an electron micrograph. The short axis length a indicates the length of the axis (short axis) that passes through the bisecting point of the long axis and has the shortest distance.

As a method of arbitrarily selecting crystals in an electron micrograph, for example, five lines were drawn on the photograph in each of the vertical and horizontal directions at 1 cm intervals, and the crystals located at the intersections of the lines were selected. The major axis length b and minor axis length a of these crystals were measured, and b/a of each crystal was calculated.

The b/a mentioned above indicates the average value of b/a of each of the crystals.

And the average particle size of the brominated anth-anthrone pigment particles (
Here, it means the average value of the long axis length. ) is 2μ
It is preferable to set it below the city level. That is, by making the particles finer to 2 μm or less, it is possible to prevent the influence of the particle size on the surface of the photoreceptor, to make the surface of the photoreceptor smooth, 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, but 1 μm or less
It is more desirable to have a thickness of 0.5 μm or less, and even more preferably 0.5 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 resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, Addition polymer resins, polyaddition resins, polycondensation resins such as polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more repeating units of these resins, such as vinyl chloride-vinyl acetate. Copolymer resin, vinyl chloride
Examples include vinyl acetate-maleic anhydride copolymer resin. However, the binder resin is not limited to these (all resins commonly used for such applications can be used).

The carrier transporting substance used in the present invention consists of an amine compound having the above-mentioned general formula, and these are exemplified below.

Incidentally, the above carrier transporting substances are used to constitute the carrier transporting layer, but they may also be contained in the carrier generation layer. A single-phase dispersion type of both of these substances may be used.
Further, the carrier generation layer may have a thickness of 0.1 to 10 μm, and the carrier transport layer may have a thickness of 5 to 30 pm. In addition,
By including a carrier transporting substance in the carrier generation layer, the sensitivity can be improved particularly in the case of a positively charged configuration.

Note that there is a preferable range for the ratio of the carrier-generating substance and the carrier-transporting substance described above. For example, when configured for negative charging, the ratio of the gear generation substance to the binder is preferably 0 to 100 weight percent (particularly 0 to 10 weight percent), and the carrier transport substance is preferably 10 to 500 weight parts.

Further, in the carrier generation layer which is particularly present on the surface side of the photoreceptor for positive charging, the carrier generation substance is added to the binder resin, carrier generation substance/binder resin -10 to 300 parts by weight/100 parts by weight (preferably 30 parts by weight).
If the content is within a specific range of 200 parts by weight/100 parts by weight, it is possible to provide a positively charging window light material with less reduction in residual potential and acceptance potential. Outside the above range, if the amount of the carrier-generating substance is small, the photosensitivity will be poor (and the residual potential will increase), and if it is too much, the acceptance potential will tend to decrease.Also, the content of the carrier-transporting substance is also important; material/
Binder resin = 20 to 200 parts by weight/100 parts by weight (
If the range is preferably 30 to 100 parts by weight/100 parts by weight, the residual potential will be small and the photosensitivity will be good, and the solvent solubility of the carrier transport substance will also be maintained well.

Outside this range, if the amount of the carrier transport substance is small, the residual potential and photosensitivity tend to be biased, and if it is too large, the solvent solubility tends to deteriorate. The content range of this carrier transport substance may be the same for the carrier transport layer.

In addition, when using the carrier-generating substance and the carrier-transporting substance together in the carrier-generating layer, the weight ratio of the carrier-generating substance to the carrier-transporting substance is (1:0) in order to effectively exhibit the respective functions of both substances. .2)～(1:3
), and more preferably (1:0.4) to (less than 1:2.0).

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

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

Month 1 special: "-Carrier generation layer-■: 4,10-dibromoanthrone 40 purified by sublimation
g was placed in a porcelain ball mill and ground at 40r, p, m for 20 hours, then polycarbonate "Panlite L-
20 g of 1250J (manufactured by Kijin Kasei Co., Ltd.) and 1.300 mA' of 1,2-dichloroethane were added and subjected to dispersion treatment for 30 hours to obtain a coating liquid for forming a carrier generation layer.

Using a portion of the obtained coating liquid, dibromoanthrone was subjected to leak excitation and the half width of the X-ray diffraction spectrum was measured, and the following results were obtained.

Δθ (18,4')≦0,57 Δθ (26,7°)≦0.66 b/a = 3.2 b = 0.4 μ Using this coating liquid, form a carrier generation layer as follows. was formed.

That is, on a polyester film on which aluminum was vapor-deposited, an intermediate layer with a thickness of 0.1 μm made of vinyl chloride-vinyl acetate-maleic anhydride copolymer "Esle Ri MF-10" (manufactured by Tsukisui Kagaku Co., Ltd.) was formed. Established.

Next, the coating liquid for forming a carrier generation layer was applied onto the intermediate layer to form a carrier generation layer having a thickness of 1 μm.
This was sealed with a carrier generation layer.

Carrier generation layer - ■: = 50 g of regular 4.10-dibromoanthrone
・Put it in a magnetic ball mill and add nitrobenzene 1.00
Add 0me and 10ml of sulfuric acid, 3Qr, p, m, 3
0000 hours dispersed. This was filtered, washed and dried to obtain highly crystalline dibromoanthrone.

40 g of this dibromoanthrone was placed in a magnetic ball mill and ground for 1 hour at 40r, p, m, and then mixed with 20g of polycarbonate "Panlite L-1250J (manufactured by Kijin Kasei Co., Ltd.) and 1,300ml of 1,2-dichloroethane.
j! was added and dispersed for 24 hours to obtain a coating solution for forming a carrier generation layer.

Using a portion of the obtained coating liquid, dibromoanthrone was subjected to leak excitation and the half width of the X-ray diffraction spectrum was measured, and the following results were obtained.

Δθ (18,4°) ≦0.36 Δθ (26,7°) ≦0.49 b/a −2,8 b =0.8 μUsing this coating liquid, form a carrier generation layer as follows. was formed.

That is, on a polyester film laminated with aluminum foil, a vinyl chloride-vinyl acetate-maleic anhydride copolymer "SRESOC MF-10J (Sekisui Chemical Co., Ltd.! I) was applied.
An intermediate layer with a film thickness of 0.1 μm was provided.

Next, the coating liquid for forming a carrier generation layer was applied onto the intermediate layer to form a carrier generation layer having a thickness of 1 μm.
This was sealed with a carrier generation layer-■.

Carrier transport layer: 7.5 g of carrier transport substance and 10 g of binder resin in 1,2-dichloroethane 80 mA? A liquid with a thickness of 100% is applied to the carrier/F:, and a film thickness of 1 is applied on the layers -■ and -■.
5μ to form a carrier transport layer, Examples 1 to 6
Electrophotographic photoreceptors (1) to (6) of the present invention were prepared.

These have the structure shown in Figure 4A.

1. A solution obtained by dissolving 7.5 g of tetraethylbenzidine represented by the following structural formula and 10 g of polycarbonate as a carrier transport substance in 80 ml of 1,2-dichloroethane was poured onto the carrier generation layer-〇 used in Examples 1 to 3. The film thickness is 15
A comparative photoreceptor (1) was prepared by coating the sample so as to have a thickness of μ.

Comparative Example 2 A comparative photoreceptor ( 2) was created.

Friend construction 1 An intermediate layer with a film thickness of 0.1 μm made of vinyl chloride-vinyl acetate-maleic anhydride copolymer “S-LEC MF-10J (manufactured by Miki Kagaku Co., Ltd.) was provided on a polyester film laminated with aluminum. On top, the same carrier transport layer used in Example 1 was applied to the membrane FQsμ.

Further, the coating liquid for forming a carrier generation layer used in Examples 1 to 3 was applied thereon to form a carrier generation layer with a thickness of 1.5 μm, thereby producing an electrophotographic photoreceptor (7) of the present invention. did. This consists of the structure shown in Figure 4B.

Electrophotographic photoreceptor (1) of the present invention obtained in the above examples
- (7) and comparative photoreceptors (1) - (2) were mounted on a photoreceptor tester (manufactured by Konishiroku Photo Industry), and a surface electrometer "Electrostatic Portometer 144 D-ID type J" was installed.
(manufactured by Monroe Electronics Incorporated), the charging position was set to V0 (■), and the surface potential was set to 600.
Exposure amount EF' required to reduce from ■ to 100 V: (
AX・5ec) and the surface potential was set to 600 ■, and the potential retention rate, D, (%) after 5 seconds was investigated.

In addition, a test was repeated 5,000 times to examine the stability of the fourth electrification position.

In addition, for samples whose charge level is less than 600 V, the charge current is increased from the standard value to increase Ef and D.
, was measured. Also, E': is 25℃ and 10℃
Measurements were made in two environments.

The results are shown in the table below. The carrier transport materials used on each side are as follows.

T-1 T-2 T-3 T-4 Ratio-1 As is clear from the above results, the electrophotographic photoreceptor of the present invention has better anger intensity and potential retention than the comparative window photoreceptor,
It exhibits very good characteristics, with little fatigue deterioration even after repeated use, excellent potential stability, and little loss of sensitivity even under low-temperature conditions.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and include FIG.
FIGS. 2, 3, 5, and 6 are X-ray diffraction spectra of the carrier-generating substance, and FIGS. 4A and 4B are cross-sectional views of the electrophotographic photoreceptor. In addition, in the symbols shown in the drawings, 1-・----1・-・-・4 electric substrate 2--1--・
−・−・−・Carrier generation layer 3 −・−・−・−・・
...It is a carrier transport layer. Agent Patent Attorney Hiroshi Aisaka Figure 5 Figure 6 2e (, t) Turning Bo Mail (GuQ Heko) 0 Treasure 1 Nachiaki (Pregnancy - D, > - Ri (Order) Procedure Nefu Seisho (Method) ) January 31, 1985 1, Indication of the case 1985 Patent Application No. 236971 2, Name of the invention Photoreceptor 3, Person making the amendment Relationship to the case Patent applicant address 1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Chome 26-2 Name
(127) Konishiroku Photo Industry Co., Ltd. 4, agent 8, ? ! Supplement the correct content type printed 1IIi1:, specification, and official drawings as shown in the attached sheet.

Claims (1)

[Scope of Claims] 1. A photoreceptor in which brominated anthanthrone represented by the following structural formula is used as a carrier-generating substance, and an amine-based compound represented by the following general formula is used as a carrier-transporting substance. Structural formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ General formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, in this general formula, R_1 represents a divalent aromatic group or a heterocyclic group. R_2 , R_3, R_4 and R_5 are mutually different or the same groups, and represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.)