JPS62163060A - Electrostatic charge generating layer and electrophotographic sensitive body containing said layer - Google Patents

Abstract

PURPOSE:To obtain the titled body having a good electrostatic charge generating layer which has good electric performance and peeling strength and having an excellent sensitivity in a near infra-red range by using a specific electrostatic charge generating material to the titled body, and by depositing and transforming the crystal of the prescribed material with an org. solvent. CONSTITUTION:The diameter of the crystal fiber which is made of chlorinated aluminium phthalocyanine [AlClxPcCly (the degree of chlorination: (x+y)=0.1-0.2, Pc: the phthalocyanine ring)] and grows in a fibrous net state, is 50-500Angstrom , preferably 100-300Angstrom . The space of the adjacent fibers is <=0.1mum. The fiber has an entwined state and has the X ray diffraction diagram which shows a peak at Bragg angle (2theta+ or -0.2 deg.) of 25.5 deg., and has an absorption at a near infra-red range. The titled body has a high electrostatic charge generating quantum efficiency due to the absorption of light at the near infra-red range and has high mechanical strength. The sticking strength of the titled body between the electrostatic charge transfer layer and the electrostatic charge generating layer becomes strong.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention stably has high photosensitivity up to the long range of the near-infrared region. This invention relates to a charge generating layer having a specific crystalline structure of a secondary photographic photoreceptor, and a laminated electrophotographic photoreceptor formed by laminating the same.

(Prior art) Traditionally, solid materials have been known as electrophotographic photoreceptors, but in recent years, electrophotographic photoreceptors that can be used in laser beam printers that use semiconductor lasers with emission wavelengths in the near-infrared region have been developed. It is highly desired.

Therefore, it is used as a photoreceptor with sensitivity in the near-infrared region.

Many studies have been conducted on functionally separated laminated photoreceptors in which the functions are separated into two layers, a charge generation layer (CG layer) and a charge transport layer (C77m), and the optimal material can be selected for each layer. In particular, with regard to the charge generation layer, which is the key to high sensitivity in near-infrared light, five different materials and thin film formation methods are being intensively studied. The material used is phthalocyanine arsenic, and the thin film formation methods mainly studied include a dispersion coating method and a vapor deposition method.

The dispersion coating M method involves pulverizing phthalonanine, finely dispersing it in a binder resin, and forming a thin film as a charge generation layer by dip coating, and is actually a method used on an industrial level. It is.

However, as can be seen from its composition, the charge generation layer made of a single-dispersion coating film is a mixture of two substances, a charge generation substance and a resin, so an interface occurs between the two substances.
Electrically, this area becomes a charge trap and poses a problem in terms of hypochondriacal performance.

In fact, there is a major problem in that the electrical performance deteriorates during repeated use over a long period of time, significantly reducing the printing durability of the photoreceptor.

On the other hand, in order to eliminate such drawbacks, research has been carried out on a charge generation layer made of a uniform thin film of the same material by vapor depositing the charge generation material in high-X air.

In particular, sublimable phthalocyanine compounds are being considered as materials that can be deposited, and At, Ti, In, and the like are being considered as central metals. In addition, in order to have sensitivity in the near-infrared region,
Since the vapor-deposited film as it is does not absorb in the near-infrared region, it is immersed in an organic solvent and undergoes crystal modification to shift the absorption wavelength region to the near-infrared region. However, phthalocyanine compounds have crystal polymorphic properties.

After going through a complicated process of vapor deposition and crystal transformation, the resulting thin film of charge generation takes on various crystal forms, and it is not always possible to obtain an ideal crystal form or to control the form. The current situation was that it was not.

(Problems to be Solved by the Invention) Next, although the charge generation layer formed by vapor deposition and organic solvent crystal transformation was expected to have high performance in terms of electrical performance due to its structure, in reality it was not. Electrical performance varies widely, making it practical.

It was very difficult to use industrially.

In other words! A charge transport layer is formed on the charge generation layer.

[Evaluation: In terms of electrical performance, surface potential V when not exposed to light. , V-boo, the surface potential v, (image potential) during exposure varies greatly. There were problems such as poor charge transfer during corona charging, low vo, and very poor sensitivity and high V. i'fc,
There was also a problem that the adhesive strength between the charge transport layer and the charge generation layer varied greatly, and in bad cases, the charge transport layer easily peeled off from the drum.

(Means for Solving the Problems) With the above-mentioned problems in mind, the present inventors developed a method using [aluminum phthalocyanide chloride as a charge-generating material] [AtCL
xPCCty (salt g (degree of humidity: x-1-y=1.0-2.
0 )], aiming at the expected electrical performance of the charge generation layer by vapor deposition and organic solvent crystal transformation, as well as aiming at reproducibility and performance stability that can be used for practical and industrial purposes. The present invention has been arrived at as a result of extensive research into the optimal crystalline form.

That is, in the present invention, chlorinated aluminum phthalocyanine [AtCl, xPCCLy (chlorine rhyg: x + y = 1.o ~ 2,0.PC: phthalocyanine term)] is used as a charge generating material, and a thin film is entirely formed by vapor deposition. After that, crystal transformation is carried out using an organic solvent to form a specific crystal form, thereby providing a high-performance charge generation layer with high electrical performance and high mechanical adhesion strength at 9 constant.
An electrophotographic photosensitive material Ij- having sensitivity in the near-infrared region obtained by laminating a charge transporting layer on the charge generating layer is provided.

The charge generating material of the present invention includes chlorine-1 hyaluminum phthalocyanine CAtCtxF'cCty (chlorinated U:
x-4-y=1.0~2,0. Pc: Phthalocyanine Enoki)], and sublimation purification is performed as a percent purification process prior to vapor deposition.

In the present invention, the above phthalocyanine is
Under a vacuum of rr to 10-'Torr, an At sheet or an At drum as a conductive substrate, and an At sheet or an At drum on which a resin thin film was formed as a 797 layer
It is formed as a vapor deposited film on the drum.

In explaining the above deposited film, an example of an X-ray diffraction pattern and a scanning reflection electron microscope (SgM) image are shown in FIGS. 1 and 2.

Next, the reflection/absorption spectrum of the deposited film is as shown in FIG.

In other words, the X-ray diffraction pattern of the 7-thalocyanine thin film in this film thickness range that is actually used shows a small peak at the Plagg angle (2θ ± 0.2 degrees) of 26.5 degrees due to the film thickness and crystal orientation. Only. It was a cabinet. The SEM image is
It shows a granular structure with a diameter of about 300 to 500×. The reflection/absorption spectrum of the deposited film clearly does not have absorption in the vicinity of 780 to 8 S Onm, which is the emission wavelength of a semiconductor laser, and is therefore unsuitable for charge generation, which has sensitivity in the near-infrared region. Therefore, in order to maintain sensitivity in the near-infrared region, it is necessary to perform crystal modification by immersing it in an organic solvent. The organic solvent used for the transformation is preferably a solvent that has some fermentability with respect to the charge generating material, such as tetrahydrofuran, toluene, xylene, etc.

As an actual example, the results of crystal transformation of a friend using toluene pressure are shown in FIG. 4 for its X-ray diffraction pattern, FIG. 5 for its SEM photograph, and FIG. 6 for its reflection/absorption spectrum of the deposited film.

The X-ray diffraction pattern is determined by the Shiprag angle (2θ±
0.2 degrees) showed a small peak at 25.5 degrees.

The SEM photograph shows fibrous crystal growth as a specific crystal morphology, which is different from that after deposition.

However, the reflection absorption spectrum shows an absorption spectrum in the near-infrared region, and has performance as a charge generation layer in the near-infrared region.

In fact, a CT layer was laminated on the surface to create a four-electron photoreceptor, and its performance was evaluated.

(2) indicates good charge, and V indicates high sensitivity and low sensitivity, and there was no peeling of the charge transport layer.

Based on the above knowledge, when the above operation was actually investigated by creating a practical photoreceptor drum at an industrial level, it was found that there was a very large variation in electrical performance, that is, 1 surface charge potential V. There are variations in the surface potential, especially in the dark, the surface potential is poor and low, and the dark decrease is large, and f movements occur in the image potential Vi during constant exposure.Furthermore, the charge transport J- It was found that the contact strength of the charge generation layer varied greatly. For this reason, we have carefully considered the electrical performance (1) of charge generation with weak mechanical adhesive strength (1-) and the identification of a charge generation layer that does not have any performance problems.
The X-ray diffraction pattern and reflection absorption spectrum of the charge generation layer with performance problems are as shown in FIGS. 7 and 8.
The plug angle is 1f (2θ±0.2 degrees) -25.5 degrees, and the 1 reflection absorption spectrum is almost indistinguishable from those with good performance as shown in FIG. In order to establish the optimal state for the crystalline form of the ``hL charge generation layer'', Kim and Mae et al. conducted well logging and found that SgM in the ``charge generation layer'' had performance problems.
As shown in Figure 9, the fibrous crystal growth is large and the tangled state of the fibrous crystals is very sparse, and a very thin blade film that appears to be amorphous is formed. It has been found.

In other words! As shown in Figure 5, the load generation layer is
It grows like a fiber and the m crystal (white part) has a diameter of 50~50mm.
1A, preferably 100 to 300, the fiber spacing is 0.1 μm or less, the fibers are completely entangled, and the X-ray diffraction shows a peak at a plug angle (2θ ± 0.2 degrees) of 25.5 degrees. A charge generation layer having a shape and absorbing in the near infrared t
P! It exhibits exceptionally good performance. In this way, due to the high fiber entanglement density, not only the charge generation quantum efficiency with light absorption pressure in the near-infrared region is high, but also the mechanical strength is high. In terms of electrical performance, the surface potential V in the dark. - Also, the surface potential (1) at constant laser exposure is low, and sensitivity is high.

Friend, 1, the adhesive strength between the cargo transport layer and the charge generation layer is also very strong.

Therefore, identifying the X-ray diffraction pattern and absorption spectrum is insufficient to identify whether the 'fIL load-generating layer is good or bad. Good performance can only be reproduced and stabilized by identifying and realizing its fibrous structure. Sex, that's what you get.

The conductive substrate of the #I type laminated electrophotographic photoreceptor of the present invention may be any of those commonly used, and has the function of an electrode and a holding material.

That is, an aluminum sheet can be used as a drum, or a plastic sheet or drum can be formed with a thin layer of aluminum by vapor deposition. The next layer, a barrier layer, may be provided as necessary, and has a rectifying function, in particular, to prevent carrier injection from the electrode and to smoothly transport photogenerated carriers from the charge generation layer to the electrode. It is something that can be done next. Commonly used polyamide, polyvinyl alcohol, nitrocellulose, etc.
12E can be used. A charge generation layer, which is a feature of the present invention, is formed thereon, and a charge transport layer is further formed thereon to form an electrophotographic photoreceptor. It is commonly used because it is necessary for the carrier to be smoothly injected and further transported quickly to the surface.

Polycarbonate small molecule charge transport agents, such as pyrazoline, and dracin, triphenylmethane, enamine, oxadiazole and its derivatives.

% dispersed in a binder resin such as polymethyl methacrylic V-) or polyvinyl cabazole.

Polyvinylanthracene. Poly(2,6-simethoxy-9,10-anthracenylene-1,10-decanedicarboxylate), poly(2-methoxy-9,10-andracenylene-1,1) with anthracene as the main chain skeleton
A layer consisting of a charge transport agent consisting solely of a polymer such as (0-decanedicarboxylate) can be used.

When realizing a charge generation layer that has a specific fibrous structure with good performance, we have carefully studied the controlling factors and found that water management from vapor deposition to organic solvent transformation process is extremely important. It was discovered that the trace amount of water in the solvent is very important and is the key point of the present invention, leading to the present invention.

In other words, it is better for the gas to contain water when the vacuum is broken during vapor deposition than to contain no water at all, and it is better to use a gas that contains water in the organic solvent than to contain no water at all in the organic solvent used during crystal transformation. It is necessary that water be contained in the amount of 150 to 500 pn, preferably 250 to 35011%. Under conditions other than these, the fibers are intertwined in a very coarse crystalline form as shown in Figure 9! /14, which does not result in good charge generation.

(Examples) Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto in any way.

Example 1 41! on an aluminum drum as a substrate.

As a barrier layer, polyamide resin T-film thickness 5aOX
A thin layer of chlorine-1 hyaluminum phthalocyanine CAtCtxPcCty (degree of chlorination:
x+y=1.5)] as the charge generating material, the degree of vacuum is about I
A vessel that performs vacuum type 7F under a vacuum of X 10-'Torr. Next, it is impossible to measure the deposited film in a strict sense.
The amount of deposited film is 1m x 2crR as a sample.
Collect the area and soak it in methanol 5-.

The phthalocyanine was completely eluted and the absorption spectrum of the solution was measured in a quartz cell with an optical path length of 1 crn.
Measure the absorbance at 0 m and determine the amount of adhesion based on the absorbance. The absorbance at this time was 1.31.

As a break gas during vacuum busheeking, 25C1 air with a relative humidity of 50 degrees was used. The X-ray diffraction pattern of the Group 7M film at that time was as shown in Figure 1, the SEM image was as shown in Figure 2, and the opposite absorption spectrum was as shown in Figure 5.

Toluene was used as an organic solvent for crystal transformation, the moisture content in the solvent was set to 300p-, and the solvent temperature was 45C, and about 1
It was immersed for 0 minutes to undergo crystal transformation. The X-ray diffraction pattern of the crystal modified film is as shown in FIG.

A small peak was observed at a Plagg angle (2θ±0.2 degrees) of 25.5 degrees, and the SEM photograph thereof showed a crystal form Fu4 in which crystals grown in the form of fibers were tightly entangled, as shown in Figure 5. % 2,5-bis(4-diethylaminophenyl) on the At drum with the charge generation layer created by pressing in this way.
- 8M parts of 1,3,4-oxadiazole, polycarbonate as binder resin (manufactured by Jojinsha, Panlite)
8 parts by weight, and 200 parts of methyl ethyl ketone as a solvent.
After applying a bath solution consisting of heavy I parts, it was dried at 100'C for about 5 minutes.

A charge transfer layer having a thickness of about 15 μm was created to obtain an electrophotographic photoreceptor. The evaluation results as electrophotographic photoreceptors are summarized in Table 1. It shows good performance in both electrical performance and peel strength.

The electrical performance was measured as follows. The conditions were that the corotron charger voltage was -5.5 kV, the drum outflow current was -52 μA, the drum rotation speed was 8 crn/see, and the surface potential without laser exposure was V. Then, exposure was performed at a laser exposure dose of 1.5 μJ/d (emission wavelength: 790 nm), and the image potential vi was measured. A surface potential meter manufactured by TREK was used to measure the surface potential. In addition, the adhesive strength between the charge transport layer and the charge generation layer can be determined by making a #1α square scratch on the photoconductor with a safety razor, adhering packing tape to the above area, and peeling it off. It was decided whether or not to do so. The plug angle 2θ was measured using ordinary CuKα1 radiation.

Example 2 The preparation of the charge generation layer was carried out in the same manner as in Example 1, and the charge transport layer was made of poly(2,6-simethoxy9.10-
A solution of 15 parts by weight of anthracenylene (1.10-decanedicarboxylate) and 100 parts by weight of trichloropropane was coated, dried at 100C for 60 minutes, and the film thickness was 1.
Created an electrophotographic photoreceptor with a 5 μm charge transport layer.

The evaluation results are summarized in Table 1, and showed good performance in both 6ff, electrical performance, and peel strength.

Example 3 The process up to the preparation of the charge generation layer was carried out in the same manner as in Example 1. As the charge transport layer, poly(2-methoxy-9°10-anthracenylene-1,10-decanedicarboxylate) 1 was used.
A solution consisting of 4 parts by weight and 100 parts by weight of trichloropropane was applied and dried at 100C for 60 minutes to form a film with a thickness of 15 μm.
An electrophotographic photoreceptor with a charge transport layer was created. The evaluation results are summarized in Table 1. It showed good electrical performance and peel strength.

Comparative Example 1, 2.3 In Example 1.2.3, 1! Example 1, except that the water content in toluene used as an organic bath medium for crystal transformation was 100- or less when creating a charge generation layer.
A tic@ charge generation layer and a charge transport layer were formed in the same manner as in Example 2.5, and electrophotographic photoreceptors corresponding to Examples 1 and 2.3 were obtained as Comparative Examples 1 and 2.3. The X-ray diffraction pattern of the charge generation layer shown in Comparative Example 1.2.5 has a plug angle (2θ±0.2 degrees) of 25.5 as shown in FIG.
However, as shown in Photo 5, the SEMI powder has large fibrous crystal growth, and the entangled state is very sparse, and there is a very thin thin film that seems to be amorphous. covered the surface. As shown in Table 1, the electrical performance and peeling performance are clearly inferior to those of Example 1.2.5.

Table 1 (Effect of the invention) As can be seen from the above examples of the present invention and comparative examples.

According to the present invention, an electrophotographic photoreceptor is obtained which has a charge generation layer with good 1 ft air resistance and peel strength, and is sensitive in the near infrared region.

[Brief explanation of drawings]

Fig. 1 is an X-ray diffraction pattern of the vapor deposited film after vapor deposition in the present invention, Fig. 2 is a surface image of the vapor deposited film taken by a scanning reflection electron microscope, Fig. 3 is a reflection absorption spectrum of the vapor deposited film, and Fig. 4 is an X-ray diffraction pattern of the charge generation layer after crystal modification with an organic solvent, Figure 5 is a surface image of the charge generation layer taken by a scanning reflection electron microscope, and Figure 6 is the reflection of the charge generation J-. Absorption spectrum. Figure 7 is an X-ray diffraction diagram of a charge generation layer with a performance problem after undergoing crystal modification with an organic solvent, Figure 8 is a reflection absorption spectrum of the same charge generation layer, and Figure 9 is an X-ray diffraction diagram of the same charge generation layer. This is a surface image taken using a scanning reflection electron microscope.

Claims (2)

[Claims] (1) Chlorinated aluminum phthalocyanine [AlCl_
xPcCl_y (degree of chlorination: x+y=1.0-2.0,
Pc: phthalocyanine ring)] The fibers of the crystals grown in a fiber network have a thickness of 50 to 500 Å, and the adjacent fibers have an entangled form with a spacing of 0.1 μm or less,
A charge generation layer of an electrophotographic photoreceptor having an X-ray diffraction pattern showing a peak at a Plagg angle (2θ±0.2 degrees) of 25.5 degrees and having absorption in the near-infrared region. (2) In a functionally separated laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive substrate or a barrier layer provided on a conductive substrate, the charge generation layer is made of chlorinated aluminum phthalocyanide. [AlCl_xPcCl_
y (degree of chlorination: x + y = 1.0 to 2.0, Pc: phthalocyanine ring)] The thickness of the fibers of the crystal grown in a fiber network is 50 to 500 Å, and the distance between adjacent fibers is 0. .It has an entangled morphology with a diameter of 1 μm or less, has an X-ray diffraction pattern that shows a peak at a plug angle (2θ ± 0.2 degrees) of 25.5 degrees, and has absorption in the near-infrared region. Separate laminated electrophotographic photoreceptor.