JPS5971057A - Electrophotogaphic receptor - Google Patents

Abstract

PURPOSE:To provide a titled photoreceptor which is highly resistant to scratching and has improved dispersibility of a charge transfer agent in the stage of filming by using a new resin as a binder resin for a charge transfer layer. CONSTITUTION:A charge transfer layer consists of an electron donative or acceptive charge transfer agent and a synthetic resin binder which is a polycarbonate Z resin alone or a blend or combination of a polyester carbonate resin and a polycarbonate Z resin. The polycarbonate Z resin is expressed by the structural formula shown on the right.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor having a charge generation layer and a charge transport layer separated in function, and particularly to the composition of the charge transport layer.

Electrophotographic photoreceptors include a single-layer type in which a charge generation layer and a charge transport layer are in the same layer, and a laminated type photoreceptor in which a charge generation layer and a charge transport layer are separated. FIG. 1 shows the structure of a conventional laminated type photoreceptor. That is, FIG. 1 is a schematic cross-sectional view of a conventional laminated photoreceptor. In FIG. 1, a photoreceptor 1 comprises a charge transport layer 2, a charge generation layer 5, a conductive layer 4, and a substrate material 5. As a result of lamination, which increases the degree of freedom in selecting materials for electrophotographic photoreceptors, it has become possible to fabricate photoreceptors using organic materials.

Examples include EVA, chloroaluminum chlorophthalocyanine (hereinafter abbreviated as At0tPcO4)-hydrazone compound layered photoreceptor, selenium-polyvinyl carbazole layered photoreceptor, azo pigment-pyrazoline layer photoreceptor, and the like. To briefly explain the process of electrophotography, the surface of the charge transporting waste 2 shown in FIG. 1 is uniformly charged with corona. Next, when image exposure is performed, charges corresponding to the image are generated from the charge generation layer 5, and the charges move in the charge transport layer 2, completely neutralizing the corona charges on the surface of the layer 2. As a result, an electrostatic latent image is formed on the surface of the charge transport layer of the photoreceptor 1. Next, a developer consisting of toner and carrier is brought into contact with the electrostatic latent image on the photoreceptor to visualize the image. This visualized image is transferred to paper or the like and fixed.

In the electrophotographic process described above, the charge transport layer 2
plays an important role. This charge transport layer is composed of an electron-accepting substance or an electron-donating substance, usually called a charge transport agent, and a binder resin that disperses and holds the substance. The conditions required for binder resin are (1) transparency;
(2) good compatibility with the charge transport agent; (3) soluble in the solvent used during coating; (4) excellent high voltage resistance; (5) free from impurities that trap charges. (6) has good adhesion (especially with the charge generation layer); (7) forms a tough film and is resistant to abrasion and scratches; (8) does not allow toner filming. There are some things that are difficult.

As binder resins that almost satisfy the above conditions, polycarbonate resins, polyester resins, polymethyl methacrylate resins, etc. (JP-A-54-59145, JP-A-5
7-4051, but a resin satisfying all the conditions has not been obtained. For example, polymethyl methacrylate resin has poor scratch resistance and many scratches occur on the surface of the charge transport layer when it comes into contact with a toner brush, a toner cleaning brush, or paper. In addition, when polycarbonate resin is used, whitening (presumably due to crystallization) occurs when applying the first charge generation layer, and when used as a photoreceptor, there are drawbacks such as a low receiving electric field. Ta.

In order to solve these drawbacks, the present invention uses a new resin as a binder resin for the charge transport layer.The purpose of the present invention is to create a binder resin that has strong scratch resistance and has good dispersibility of the charge transport agent during film formation. It is about providing.

That is, to summarize the present invention, the present invention is an invention of a photoreceptor for electrophotography, which is composed of a charge generation layer and a charge transport layer separated in function on a conductive support. In the photoreceptor, the charge transport layer includes an electron-donating or electron-accepting charge transport agent and a synthetic resin binder that is made of a polycarbonate z resin alone or a blend or combination of a polyester carbonate resin and a polycarbonate z resin. The polycarbonate z resin and polyester carbonate resin used in the present invention have the following structure.

Polycarbonate z resin (hereinafter abbreviated as POZ) Polyester carbonate resin (hereinafter pEe, !: abbreviated) An organic photoreceptor using these resins has a structure as shown in FIG. That is, FIG. 2 is a schematic cross-sectional view of a laminated photoreceptor having a double charge transport layer, which is an embodiment of the present invention. In FIG. 2, 10 indicates the entire organophotoreceptor according to the present invention. 15 is a substrate, which has a thickness of 75 μm in Fig. 2.
Polyester film (PET) i is used.

Reference numeral 14 denotes a conductive layer, which is made by vapor-depositing aluminum of about 11000A. 15 is a charge generation layer J>klCLP
0 of various phthalocyanine compounds including AOL K.
It is vacuum deposited to a thickness of 1 to 1 μm. 16 is P
This is a charge transport layer using KO as a binder. This layer may contain electron-donating substances commonly used as charge transport agents, such as polycyclic aromatic compounds, indole, oxazole, thiazole, imidazole, pyrazole, oxadiazole, thiadiazole, triazole, and hydrazone compounds. Can be used.

This PE0-([- charge transport layer as a binder mainly contributes to improving adhesion to gold. When coating this PE0 layer, PEC is a charge generating layer of At(
:jtPcOl It is preferable to use a dilute polymer solution at the time of coating so that the solution passes through the vapor deposited film and permeates to the conductive layer 14. The amount of charge transfer agent contained in this layer is 10% of the total solids after drying including the binder resin.
It is preferable that it is 80%. 17 is a charge transport layer using a POZ-i binder. Similarly to 16, this layer also contains an electron donating substance as a charge transport agent with a total solid content of 10
Contains ~80%. paz has good compatibility with pEc,
Moreover, since it is non-standard, the charge transport agent has good dispersibility, and the resin does not whiten during coating, so it is not uniform even when combined with a charge transport layer using 16 PEO' (z binder). A transparent charge transport layer is obtained.

Furthermore, in the organic photoreceptor shown in FIG. 2, a similar effect can be obtained by integrating all of the charge transport layers 16 and 17, that is, by blending pcz, which is an inder resin, with PEO.

Examples and comparative examples of the present invention are shown below, but the examples are representative examples of the present invention and do not specify the content of the present invention. iqb
Example 1 Alc3LP, a charge generating layer material, is deposited on a conductive support deposited on a polyester film (PET) with a thickness of 100 μm to a thickness of aluminum Q I Q OOA.
col f Q, vacuum deposited to a thickness of 6-1 μm. This is left in saturated vapor of tetrahydrofuran for 12 hours or more and dried to form a charge generation layer (Patent Application No. 57
-59484) 0 Next, coating liquid 1'5r for charge transport layer having the following composition was applied first and then 2 on this charge generation layer, and the total film thickness after drying was 20 μm for charge transport. A photoreceptor with layers was obtained (coating solution 1) O chloroform (solvent) 90
(Coating liquid 2) o pcz (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
10 thiO chloroform
80% Example The charge generation layer was the same as that used in Example 1, and the coating solution had the following composition, namely, a blend of paz and puc was used as the binder resin. The thickness of the charge transport layer is 20 μm.

(Coating liquid 5) OPGZ (manufactured by Mitsubishi Gas Chemical Co., Ltd.) 7
%OFKO (2:1 ratio of ester to carbonate) 5%
O chloroform 80
% Example 6 The same charge generation layer as that used in Example 1 was used, and the coating liquid had the following composition.
The thickness of the L cargo transport layer is 20 μm.

(Coating liquid 4) o POZ (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
10% O chloroform
80% Comparative Example 1 The same charge generation layer as used in Example 1 was used, and the coating liquid had the following composition.The thickness of the fully circular zero charge transport layer was 20 μm.

(Coating liquid 5) O chloroform 8
4% Each of the photoreceptors shown in the Examples and Comparative Examples shown above was tested for photosensitivity properties (sensitivity, accepted electric field, dark half-life, scratch resistance, and adhesion). It is shown below.

1. Photosensitive characteristics Commercially available electrostatic charge tester (5p-42 manufactured by Kawaguchi Electric Co., Ltd.)
8) Photosensitivity characteristics were measured using f. Corona discharge voltage: 6
KV, irradiation light wavelength: 850 nm.

2. Scratch resistance (see Figure 3) Figure 3 shows the scratch resistance test method. In Figure 5, 1
0 is a photoreceptor according to the present invention, 21 is a steel ring, 22 is a load cell, and 25 means all weights.

A4 size Xerox paper (
A high-quality 57.5 Kl) is wound around it to make a wear ring. The photoreceptor 10 is cut out with a width of 2cIn and a length of 15mK, one longitudinal end is fixed to the load cell 22, and the other end is 15F.
Weight #) Add 25. The photosensitive surface of the photoreceptor (charge transport layer side) is brought into contact with the outer periphery of the wear ring over a central angle of 90',
250 r, p in the direction shown on the wear ring in Figure 5
, m and measure the torque at that time. After a certain period of time has elapsed, the photoreceptor is removed and scratches on the surface are measured using a surface roughness meter.

& Width 21 on the adhesive photoreceptor surface? Make scratches that reach the board at intervals of ff+, and perform 2 peel tests using adhesive tape.

Table 1 summarizes the results of various tests.
The charge transport layer for a photoreceptor using a blend or combination with PO2 effectively utilizes the scratch resistance of PO2 or the good adhesion of Pwc, so the basic characteristics of the photoreceptor, sensitivity, accepted electric field, etc. It has the advantage of improving the abrasion resistance and adhesion of the photoreceptor without reducing the properties.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a conventional laminated photoreceptor, FIG. 2 is a cross-sectional schematic view of a laminated photoreceptor with double charge transport layers, which is an embodiment of the present invention, and FIG. The scratch resistance test procedure is shown. 1.10: Photoreceptor, 2: Charge transport layer, 5, 1S: Charge generation layer, 4, 14: Conductive layer, 5, 15: Substrate material, 16
: PFO binder charge transport layer, 17: PCz binder charge transport layer, 21: Steel ring, 22: Mouth-dossel,
25: Weight 0 Patent applicant Hiroshi Nakamoto, agent of Nippon Telegraph and Telephone Public Corporation

Claims (1)

[Claims] 1. A laminated electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer separated in function on a conductive support,
The charge transport layer consists of an electron-donating or electron-accepting charge transport agent and polycarbonate z resin alone, or polyester carbonate resin and polycarbonate)7
An electrophotographic photoreceptor comprising a synthetic resin binder that is a blend or combination of resins. 2. The charge transport layer is formed from a combination of a charge transport layer made of polyester carbonate resin f/(inder) provided in the portion in contact with the charge generation layer, and a charge transport layer superposed thereon and made of polycarbonate 2 resin as a binder. Electrophotographic photoreceptor 0 according to claim 1, which is