JPH035745B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminated electrophotographic photoreceptor having high photosensitivity in the near-infrared region, particularly in the wavelength region of 750 nm or more.

[Prior art]

Conventionally, electrophotographic photoreceptors have a single photosensitive layer, which is a single layer made of an inorganic compound such as amorphous selenium, zinc oxide, or cadmium sulfide, or an organic compound such as polyvinylcarbazole-trinitrofluorenone or pyrylium salt-triphenylmethane. 2. Description of the Related Art Laminated photoreceptors are known, which are functionally separated into a charge generation layer and a charge transfer layer, and in which the charge generation layer contains selenium, a disazo compound, an indigo compound, a squaric acid derivative, or a phthalocyanine compound.

The sensitivity wavelength range of these photoreceptors, except for metal phthalocyanine compounds, are all in the ultraviolet to visible range, and the sensitivity decreases significantly in the near-infrared range of 700 nm or more. Therefore, various sensitization methods have been attempted in order to provide sensitivity in the near-infrared region, and known examples include dye sensitization using cadmium sulfide and zinc oxide, and sensitization using tellurium in selenium. Even in these sensitization methods, the sensitivity is currently significantly reduced in the long wavelength region of 750 nm or more. Furthermore, dye sensitization poses problems with the stability of the dye, and selenium sensitization with tellurium poses problems with the physical and electrical stability of the photoreceptor.

On the other hand, photoreceptors using metal phthalocyanine compounds are disclosed in U.S. Pat.
As seen in Publication No. 11136, US Pat. No. 4,214,907, British Patent No. 1,268,422, etc., the sensitivity peak varies depending on the central metal, but all are between 700 and 750 nm, and the sensitivity gradually decreases above 750 nm. The sensitivity is lowered and is not practical.

As mentioned above, the current situation is that no photoreceptor having high sensitivity at 750 nm or more has been put into practical use so far.

[Purpose of the invention]

The present invention was made to solve these problems, and its purpose is to provide a laminated electrophotographic photosensitive material that has excellent photosensitivity in the light wavelength range of 750 nm or more and has excellent printing durability. It's about offering your body.

[Structure of the invention]

That is, to summarize the present invention, the present invention relates to a laminated electrophotographic photoreceptor, in which a charge generation layer and a charge transfer layer are laminated on a conductive substrate. A charge generation layer formed by depositing titanyl phthalocyanine and then contacting it with vapor of a soluble solvent, and (A) having an infrared absorption spectrum of 727 cm ^-1 , 752
cm ^-1 , 892cm ^-1 , 1052cm ^-1 , 1072cm ^-1 , 1118cm
^-1 , has strong absorption at 1332cm ^-1 , 773cm ^-1 , 779
cm ^-1 , 879cm ^-1 , 966cm ^-1 , 972cm ^-1 , and 1160cm ^-1 , and (B) in the X-ray diffraction spectrum, Bragg angles (2θ) of 7.5°, 12.6°, 13.0°, 25.4°, 26.2°, 28.6
It is characterized by providing a charge generation layer having a crystal structure exhibiting spectral characteristics indicated by a strong diffraction peak at .degree.

The present inventors have already reported in JP-A-58-158649 that chloroaluminum phthalocyanine (hereinafter abbreviated as AlPcCl) and chloroaluminum chlorophthalocyanine were used as charge generation layer materials having excellent photosensitivity in the light wavelength region of 750 nm or more. (AlClPcCl) was shown to be superior, but as a result of intensive studies on metal phthalocyanines, as shown in Figure 1, titanyl phthalocyanine (hereinafter referred to as
We have discovered that PcTiO (abbreviated as PcTiO) exhibits excellent photosensitivity in the light wavelength range of 750 nm or more. That is, FIG. 1 shows the structural formula of PcTiO.

FIG. 2 is a schematic cross-sectional view showing an example of the structure of a laminated electrophotographic photoreceptor according to the present invention. In FIG. 2, numeral 1 is a metal substrate, 2 is a blocking layer,
3 means a charge generation layer, and 4 means a charge transfer layer.

Examples of the metal substrate 1 include conductive materials such as aluminum, copper, iron, and stainless steel. The blocking layer 2 is a thin insulating film, and if aluminum is used as the metal substrate, its oxide Al ₂ O ₃
(several tens of angstroms) plays that role. The charge generating layer 3 according to the present invention is formed by vacuum deposition followed by solvent treatment. Examples of soluble solvents that can be used include tetrahydrofuran, methanol, acetone, methyl ethyl ketone, alpha-chloronaphthalene, pyridine, and the like. The charge transfer layer 4 is a layer that transfers the charges generated in step 3 to the surface of the photoreceptor, and must be transparent to light in the photosensitive wavelength range of the charge generation layer. Alternatively, a charge transfer layer is formed by dissolving and dispersing this in a resin as a binder.

As a single transfer agent, polyvinylcarbazole, selenium, etc. can be used. Transfer agents used in the dispersed form include N-vinylcarzole, 2,5-bis(4-diethylaminophenyl)-1,3,5
-oxadiazole, 1-phenyl-3-(p-
diethylaminostyryl)-5-(p-diethylaminophenyl)-pyrazoline, 1-phenyl-3
-Methyl-5-pyrazoline, acetobenzothiazolyl-2-hydrazone, p-diethylaminoaldehyde diphenylhydrazone, and the like. In addition, as a resin for dispersing the transfer agent,
Examples include polymethyl methacrylate, polycarbonate A, polycarbonate Z, polyvinyl chloride, silicone resin, and the like. The ratio of transfer agent to resin is preferably 0.1 to 0.6. The thickness of the charge transfer layer is not particularly limited, but from the relationship with the acceptance potential, it is
A suitable thickness is 20 μm.

Below, the method for synthesizing PcTiO used in the present invention,
A method for manufacturing the charge generation layer will be described.

(1) Synthesis method of PcTiO PcTiO was synthesized based on the reaction equation shown below.

(2) Method for producing charge generation layer PcTiO obtained by the above synthesis method was deposited on an aluminum substrate to a thickness of 0.05 to 0.5 μm under a vacuum of 10 ^-5 to ^{10 -6} Torr.
It is preferably deposited to a thickness of 0.08 to 0.1 μm. This vapor-deposited film was placed in saturated vapor of tetrahydrofuran for 1~
Leave it for 24 hours.

By this solvent treatment, the infrared absorption spectrum and
The line diffraction spectra show changes as shown in FIGS. 3 and 4, respectively, and the maximum absorption wavelength region of the electron spectrum shifts to the longer wavelength side as shown in FIG. 5.

FIG. 3 is a graph showing changes in the infrared absorption spectrum due to solvent treatment of PcTiO, where the horizontal axis shows the wave number (cm ^-1 ) and the vertical axis shows the transmittance. Figure 4 is a graph showing changes in the X-ray diffraction spectrum due to solvent treatment, and the horizontal axis is the black angle (2θ);
The vertical axis indicates strength. Figure 5 is a graph showing the change in electronic spectrum due to solvent treatment.
The horizontal axis shows wavelength (nm), and the vertical axis shows absorbance.

Each will be specifically explained below. As shown in Figure 3, the solvent-treated PcTiO deposited film has the following properties:
In the infrared absorption spectrum, 727cm ^-1 and 752cm
^-1 , 892cm ^-1 , 1052cm ^-1 , 1072cm ^-1 , 1118cm ^-1 ,
It has strong absorption at 1332cm ^-1 , 773cm ^-1 , 779cm ^-1 ,
It has weak absorption at 879cm ^-1 , 966cm ^-1 , 972cm ^-1 and 1160cm ^-1 , and as shown in Figure 4, in the X-ray diffraction spectrum, the Bragg angle (2θ) is 7.5°,
It shows strong diffraction peaks at 12.6°, 13.0°, 25.4°, 26.2°, and 28.6°, and further shows a shift toward longer wavelengths from 720 nm to 830 nm in the electronic spectrum, as shown in Figure 5.

The absorption peak shifted to this longer wavelength side.
A deposited film of PcTiO was used as a charge generation layer in the present invention.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Example 1 On a charge generation layer of PcTiO having a film thickness of 0.06 to 0.08 μm prepared by the above manufacturing method, 10.7% of polycarbonate Z, 10.7% of p-diethylaminoaldehyde-diphenylhydrazone, and chloroform were added.
A solution consisting of 78.6% is spin-coated and dried at 40° C. for 2 hours in a nitrogen stream, and then dried in a vacuum dryer at 40° C. for 10 hours or more. The thickness of the charge transfer layer at this time was 15 μm.

This laminated photoreceptor is negatively charged with a 5kV discharge,
The optical attenuation of the surface potential was measured, and the amount of light (μJ/cm ² ) required to halve the surface potential was evaluated as the sensitivity.

As a result, good results were obtained with a half-reduced exposure dose of 0.5 μJ/cm ² and an acceptance potential of 600 V at 850 nm.

For comparison, a laminated photoreceptor was produced in the same manner as in Example 1 except that no solvent treatment was performed.

The spectral sensitivities of the photoreceptors of Comparative Example (A) and Example 1 (B) are shown in FIG. In other words, Figure 6 is
The spectral sensitivity of a photoreceptor with PcTiO as a charge generation layer is
This is a graph showing the relationship between wavelength (nm) (horizontal axis) and half-decreased exposure amount (μJ/cm ² ) (vertical axis). As is clear from FIG. 6, the photoreceptor according to the present invention has a sensitivity peak in a long wavelength region of 800 nm or more, and an improvement in sensitivity was observed in the entire wavelength region compared to the comparative example.

In addition, for comparison of printing durability, a laminated photoreceptor [comparison] was prepared in the same manner as in Example 1, except that AlPcCl was vapor-deposited under the same conditions as the above-mentioned PcTiO, and the layer obtained by solvent treatment was used as the charge generation layer. Example (C)] was prepared.

The evaluation was carried out by attaching a photoreceptor to a commercially available printer and measuring the change in print density when repeatedly printing on A4 size plain paper. The results are shown in FIG. That is, FIG. 7 shows the printing durability of each photoreceptor of Example 1 (B) of the present invention and Comparative Example (C).
Number of A4 prints (×10 ³ ) (horizontal axis) and optical density [log
(Io/I)] (vertical axis).

As shown in Figure 7, with the PcTiO photoreceptor of the present invention, the density decreases after printing more than 10,000 sheets.
It was found to be less than 10%. This is presumed to be because the Ti=O bond is chemically more stable than the Al-Cl bond.

〔Effect of the invention〕

As explained above, PcTiO according to the present invention
A laminated electrophotographic photoreceptor whose charge generation layer is a thin film obtained by treating a deposited film with the vapor of its soluble solvent has high sensitivity in the long wavelength region of 750 nm or more.
In addition, since it has excellent printing durability, it can be used as a photoreceptor for a laser printer using a semiconductor laser as a light source.

[Brief explanation of the drawing]

Figure 1 shows the charge generation layer used in the present invention.
The structural formula of the PcTiO compound is shown, FIG. 2 is a schematic cross-sectional view showing an example of the structure of the laminated electrophotographic photoreceptor according to the present invention, and FIGS. 3, 4, and 5 are
Graphs showing changes in infrared absorption spectrum, X-ray diffraction spectrum, and electronic spectrum due to solvent treatment of PcTiO, respectively. Figure 6 shows an example (B) of the present invention and a comparative example (B) using PcTiO as a charge generation layer. A) is a graph showing the spectral sensitivity of each photoreceptor, and FIG. 7 is a graph showing the printing durability of each photoreceptor of Example (B) of the present invention and Comparative Example (C). 1: Metal substrate, 2: Blocking layer, 3: Charge generation layer, 4: Charge transfer layer.

Claims (1)

[Scope of Claims] 1. In a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive substrate, titanyl phthalocyanine is deposited on the substrate and then brought into contact with vapor of a soluble solvent. and (A) in the infrared absorption spectrum, 727 cm ^-1 , 752
cm ^-1 , 892cm ^-1 , 1052cm ^-1 , 1072cm ^-1 , 1118cm
^-1 , has strong absorption at 1332cm ^-1 , 773cm ^-1 , 779
cm ^-1 , 879cm ^-1 , 966cm ^-1 , 972cm ^-1 , and 1160cm ^-1 , and (B) in the X-ray diffraction spectrum, Bragg angles (2θ) of 7.5°, 12.6°, 13.0°, 25.4°, 26.2°, 28.6
1. A laminated electrophotographic photoreceptor comprising a charge generation layer having a crystal structure exhibiting spectral characteristics indicated by a strong diffraction peak at .degree..