JPS5862654A - Photoreceptor for electrophotography - Google Patents

Abstract

PURPOSE:To improve photosensitivity in a composite type electrophotographic receptor provided with a charge generating layer and a charge transfer layer on a condutive substrate by dispersing the charge transfer material in the charge transfer layer microscopically heterogeneously. CONSTITUTION:In a composite electrographic receptor provided with a charge generating layer and a charge transfer layer which differ in function on a conductive substrate, the charge transfer layer contains a charge transfer material consisting of an electron attractive material such as 2, 4, 7-trinitrofluorenone or an electron donative material such as pyrazoline compd. and a binder, and the binder and the charge transfer material are used in combination in such a way that the charge transfer material disperses microscopically heterogeneously in the form of fine particles by having poor solubility in the binder, whereby the electrophotographic receptor of improved sensitivity is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly, the present invention relates to a novel organic electrophotographic photoreceptor having excellent sensitivity. It is. .

Conventionally, zinc oxide, amorphous selenium, cadmium sulfide, and the like have been widely used as photoreceptors for electrophotography by utilizing photoconductivity caused by light. However, recently, photoreceptors have become easier to process and
In addition to manufacturing costs, there is a need for a wide range of performance in terms of freedom in functional design.
Electric conductors have attracted attention, and some of them have already reached the stage of practical use.

Electrophotographic photoreceptors using organic photoconductors include:
Many photoreceptors are known including poly-H-vinylcarbazole/2.4.7-trinitrofluorenone. Organic photoconductors are relatively easy to design in terms of sensitivity and photosensitive wavelength, and are easy to handle.As a result of much research for use in future electrophotography, it has been found that organic photoconductors have a high sensitivity, are relatively easy to design for photosensitive wavelengths, and are easy to handle. This is because it has been clarified that the charge generation agent and the charge transfer agent are based on transfer, and by appropriately combining a charge generation agent and a charge transfer agent, it has become possible to obtain original electrophotographic photoreceptors with various characteristics. .

For example, JP-A-47-18543, JP-A-47-1854
No. 4, No. 47-30331, No. 47-30332, etc. are thought to be photoreceptors that were made in one shot based on this idea.

However, recently, with the aim of separating these functions more completely and creating a higher-performance photoreceptor, a charge generating agent and a charge transfer agent have been made into a multilayer structure, and a friendly member has been attracting a lot of attention. It has become the mainstream of current electrophotography state party conductors.

In each of these multilayer structures, a charge generation layer is formed by layering a special pigment as a charge generation agent on an electrically conductive substrate, and a transfer layer having charge mobility is provided on top of the charge generation layer. The light that passes through the charge transfer layer and reaches the charge generation layer is absorbed by the charge generation agent,
A charge is generated, which moves through the charge transfer agent, neutralizes the charge on the second side of the photoreceptor, and generates an original current.

In order to improve the performance of photoconductive photoreceptors for electrophotography, research is being carried out from many points such as the development of charge generating agents and charge transfer agents, and the structure of photoreceptors.

It is already known that a charge transfer layer is prepared by incorporating a charge transfer agent into a binder according to the present invention.
f # Kaisho, No. 56-422'36 contains 2.4.7-dolinitro-9-fluorenone in various binders,
It is used as a charge transfer layer. -However, as has been said in the past, 'the charge transfer layer provided on the charge generation layer needs to be transparent and homogeneous in order for the charge transfer layer to efficiently reach the charge generation layer'. The most important issue is that the transfer agent blended into the transfer layer should have good solubility in the binder used in the transfer layer.(R
Icho Technical Rapport'NO,
3s")'z] 98(1, P7, 1) As a result of extensive investigation into this problem, the present inventors have developed a method that is completely opposite to the conventional thinking, that is, I found it difficult to criticize the fact that the poor solubility of the transfer agent in the binder actually improves sensitivity.
This invention has reached the light and has nine products.

That is, the present invention provides a composite electrophotographic photoreceptor in which a charge generation layer and a charge transfer layer are provided on a conductive substrate, and the charge transfer agent in the charge transfer layer is dispersed non-uniformly under a microscope. In the present invention, the charge transfer agent has a solubility of 1 in the binder.
It is sufficient to consider a combination 5 of a binder and a charge transfer agent that are dispersed in the form of fine particles.

In addition, even if the combination has sufficient solubility, by incorporating the electrolytic transfer agent into the binder in an amount exceeding the solubility limit, the purpose can be achieved by precipitating it as insoluble particles in the system. . .

The fine particles mentioned here include everything from those that can be distinguished with the naked eye to those that can be distinguished with a microscope, but on a practical level, the size of the particles in the system must be within the lower limit of αO1μ. This refers to substances up to an upper limit of 5■, and the form must be determined in particular because it can vary depending on the combination of binder and charge transfer agent used! There isn't.

In the present invention, both electron-withdrawing compounds and electron-donating compounds can be used as charge transfer agents.

Examples of electron-withdrawing compounds include 2.4, ? -)'J nitro-9-fluorenone, 2.4.8-trinitrothioxa 7t, 3.4.5.7-tetranitro-9-fluorenone, dinitroanthracene, dinitroacridine, tridotraquinone, dinitroanthraquinone, chloral etc. can be given. 11. Examples of electron-donating compounds include (2,5-bis(4'-dimethylaminophenyl)-oxadiazole-1,3,4)
Oxadiazoles as shown in -11-phenyl-3-(P-dimethylaminostyryl)-5-(P=nidimethylaminophenyl-pyrazoline compounds such as pyrazoline), etc. can be used as a charge transfer agent. In this case, polyethylene resin, styrene resin, polyester resin, polyurethane resin, polycarbonate resin, acrylic 41F resin, butyral resin, etc. are optionally used as the binder. I can do it.

The quantitative ratio of these binders and charge transfer agents can be arbitrarily changed depending on the type of binder used, the type of charge transfer agent, and the combination thereof, but it is preferable that 1150 parts by weight of the binder per 100 parts by weight of the charge transfer agent. It is preferable to use 400 parts by weight of the binder and, if necessary, a solvent that dissolves the charge transfer agent. After being liquefied, it is coated onto the charge generation layer so that the thickness after drying is preferably 1 to 100 μm and t-j is 3 μ to 30 μm.

The conductive substrate necessary to construct the photoreceptor of the present invention is a general metal plate, such as a metal plate made of aluminum, nickel, copper, etc., or a polyester film on which these metals or tin oxide are vapor-deposited. Conductive film can be used.

Furthermore, the charge generation layer provided on the conductive substrate may be a charge generation agent such as a disazo pigment, a squarylium pigment, an indigo pigment, a cyanine pigment, a phthalocyanine pigment, a naphthalocyanine pigment, etc., or may be a superimposed film. It is used in conjunction with a forming agent or binder to form a charge generating layer.

The thickness of this charge generation layer is determined by the capacity of the charge generation agent, the type of binder, and the am of the charge generation agent, but is preferably 20μ or less, for example in the range of 3μ to α1s. In this case, as in the case of the charge transport layer above, the binder is applied using a suitable solvent. Alternatively, when a binder is not used, the charge generating layer can be formed by dispersing the charge generating agent as it is in an organic medium, coating and drying it, or by vapor deposition or other methods.

As described above, the photoreceptor of the present invention includes a charge generation layer provided on a conductive substrate, and a charge transfer layer provided thereon in which a charge transfer agent is dispersed in the form of particles of 0.01 μ to 5 μm. This is a photoelectric/conductive photoreceptor for electrophotography, but if necessary, it is also possible to provide a barrier layer on the conductive substrate or between the charge generation layer and the charge transfer layer to improve charge retention performance. It is also possible to provide an insulating layer on top of the charge transfer layer to function as surface preservation and charge retention.

Method for Measuring Sensitivity of Photoreceptor j Cut the photoreceptor into 3 scratches x 3 squares, and charge to 500V using a corotron type corona charging device (applied voltage: 6000V, positive or negative).

Next, the white light from the IKW halogen lamp is separated using Toshiba's interference filters (KL-41 to KL-710) and Toshiba's colored glass filters (L-39 to R-69), and the light intensity becomes 715 W/- by adjusting the aperture. The sample is irradiated with monochromatic light adjusted as follows.

Changes in the charged voltage are detected using an FET input electrostatic induction surface potentiometer (Journal of Electrophotographic Society, Vol. 18, No. 3, p. 79, 1980), and the time t (seconds) until the initial charged voltage is halved is determined.

Sensitivity is calculated from the reciprocal of the halved 11-party energy.

Example 1 Preparation of a photoreceptor: A 2vt-dispersion of a disan pigment (Nihon Kanto Shikisha III) shown in the following structure and trichloroethane was coated onto a 4100 μm thick aluminum foil to a thickness of 3 tones. Dry.

2.4 as the 11L cargo transport layer on top of this? -t trinitro-9-fluorenone (To'Q mH) (T, N,
v> and polycarbonate resin (manufactured by Mitsubishi Gas Chemical, Kneepilon S・100) k atrachloroethane ← hardness is 20
-30wt9G, and then melted and dispersed the polycarbonate resin and T, so that the film thickness was lθμ.
The coating was applied and dried at different ratios of N and F.

The relationship between the condition of the moving layer of the photoreceptor and the sensitivity (described above) is shown in FIG. 1.

As is clear from this, T for polycarbonate,
It is observed that as the amounts of N and F exceed a 25/75 weight ratio, fine crystals of TN and F precipitate, and beyond this point the sensitivity improves dramatically.

Microscopic photograph of Example 1; It was clearly observed that fine particles with a length of 3 seconds and a thickness of about 0.3μ were uniformly precipitated on the T, N, F/polycarbon photoreceptor prepared in Example 1. T, N, F in I41 11
．． 8-dinitroanthraquinone was used. Is 8
- dinitroanthraquinone to polycarbonate,
When it becomes 10/90 or more, fine particles with a length of 10μ and a thickness of 1μ precipitate uniformly, and the sensitivity decreases from the grain point.

A rapid rise from αlcd/μJ to 0.8 cIi/μJ was observed. .

′□,.

Implementation N3 - In place of T, N, and F in implementation IPIll, 2.
8-dinitroacridine was used, and polyester resin Pylon 200 (manufactured by Toyobo Co., Ltd.) was used as a binder. Dinitroacridine is 20/20% of polyester resin
80 or more, a small particle with a length of 5μ and a thickness of 0.1 tone is precipitated, and from this point the sensitivity is from α4-/μJ to 1.0 cd/μ
1゜Increased to J 4 In the practical example, chloral was used instead of T, N, and F, and acrylic resin (Hydaloid 100) was used as a binder.
Also, a suspension of a charge generating agent and ε-copper phthalocyanine in xylene was coated and dried to form a charge transfer layer having a thickness of 1 μm. The thickness of the charge transfer layer was 20μ. Rip tool/acrylic resin 40/6
It can be seen that when the value exceeds 0, fine particles precipitate and the sensitivity improves.

Example 5 In Example 1, 1-7Ale-3-(
P-dimethylaminostyryl)-5-(, P-dimethyllminophenyl)-pyrazoline was used to convert the 2016 salt into Dow polyethylene F'-2225 (Asahi Dow Co., Ltd. #
l) lo o parts were dissolved in 1000 parts of hot xylene. This was coated onto an aluminum foil provided with an ε-copper phthalocyanine layer of i1μ, and the aluminum foil was coated and dried while being heated and maintained at 1120°C.

Pyrazoline was found finely dispersed in 0.02μ particles using polyethylene resin as a binder in the 20μ charge transfer layer, and the sensitivity was 0.7 at 620nm.
cII/μJ and fc.

[Brief explanation of drawings]

FIG. 1 shows a sensitivity curve at a spectral wavelength of 620 nmVc. Figure 2 is a micrograph showing the fine particle structure of the photoreceptor (3,0
00 times), (2-a) has a T, N, F/polycarbonate ratio of 15/85, and (2-b) has T, N, , F
/polycarbonate ratio is 40/60. Agent Masao Miyake and 1 other person Figure 1 T, N, F/f Lina I-Bo? , -1, Medium - Figure 2 (2-a) (2-b) Procedural amendment (method) % formula %) 2 Title of the invention 'City f photographic photoreceptor 3 Relationship with the person making the amendment case Special, M applicant name (5930) Patent attorney Royal family 4, Masao (other 1
Name) 5 Date of supplementary order 1t February 4, 1981 6
Number of inventions increased by drawing 0Figure 2 (2-a) (2-b)

Claims (1)

[Claims] (1) In a composite wrinkled electronic photoreceptor in which a charge generation layer and a charge transfer layer are provided on a conductive substrate, the charge transfer agent in the charge transfer layer is A photoreceptor for electrophotography characterized by being non-uniformly dispersed. (2) The electrophotographic photoreceptor according to claim (1), wherein the charge transfer agent is an electron-withdrawing substance. (3)' The electron-withdrawing substance is 2.4.7-dolinitrofluorenone, 2.4.8-)linitrothioxanthone, 3.4.5.7-titranitrofluorenone, dinitroanthracene, dinitroacridine, nitroanthraquinone. , dinitroacridine: non-chloral, the electrophotographic photoreceptor according to claim 11(2). (4) The electrophotographic photoreceptor according to claim 1, wherein the charge transfer agent is an electron-donating substance; and (5) the electron-donating substance is an oxadiazole, a styryl compound, or a carbazole compound. The electrophotographic photoreceptor according to claim 8(4), which is a pyrazoline compound. (6) The charge generating agent in the charge generating layer is a disazo pigment, a squarylicum pigment, an indigo pigment, a cyanine pigment, a phthalocyanine pigment, or a naphthalocyanine pigment. Photoreceptor for electrophotography. (7) The charge transfer agent in the charge transfer layer is aO1 to 5
Claim (1) Uniformly dispersed with fine particles
The electrophotographic photoreceptor described in . (8) Claim (1) wherein the charge transfer layer has a thickness of 1μ to 100μ and the charge generation layer has a thickness of a1μ to 3μ.
Electrophotographic photoreceptor as described in section ゛,