JPS6057589B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor in which a photosensitive layer combining a charge carrier generating pigment and a charge transfer substance is formed on a conductive support. Regarding the body.

It is well known that various types of electrophotographic photoreceptors have been developed and used depending on the electrophotographic copying method.

However, none of them are satisfactory,
For example, selenium-based photoreceptors have various drawbacks such as poor flexibility, cannot be formed into sheets, are easily scratched, and have poor heat resistance, while zinc oxide photoreceptors have low sensitivity and printing durability. It has poor electrostatic properties and poor charging properties. In addition, charge transfer complex
Shin-type photoreceptors (composed of an electron-accepting substance and an electron-donating substance) have recently attracted attention and been put into practical use, but they cannot be said to be satisfactory in terms of sensitivity. be.

An object of the present invention is to provide an electrophotographic photoreceptor in which the above-mentioned drawbacks are solved.

As a result of various researches, the present inventors have found that certain compounds, which have been conventionally used as photoconductive substances, have been found to be effective as photoconductive substances when used in combination with charge carrier-generating pigments. Rather, it was found that the above purpose could be achieved by acting as a charge transfer material.

The present invention was completed based on this. That is, the present invention provides an electrophotographic photoreceptor in which a photosensitive layer containing a charge carrier generating pigment and a charge transfer substance is provided on a conductive support, wherein the charge transfer substance has the following general formula (wherein R1 represents an alkyl group having 1 to 11 carbon atoms, and R2 represents hydrogen, methyl group, nitro group or halogen). An electrophotographic photoreceptor characterized by containing at least one type of photoreceptor.

Here, the charge carrier-generating pigment refers to a pigment that is considered to generate charge carriers when exposed to light, while the charge transfer material refers to a pigment that injects charge carriers generated from the charge carrier-generating pigment and transfers them. refers to something that is thought to have the effect of

The charge transfer substance (1,1-bis(4-N4eN-dibenzylaminophenyl)alkanes) used in the present invention is known as a substance, and its preparation method or photoconductive substance can be used as an electrophotographic photoreceptor. Its use is also disclosed in Japanese Patent Publication No. 10983/1983.

As described above, in the present invention, as a result of this substance being combined with a charge carrier generating pigment, the resulting electrophotographic photoreceptor functions as a charge transfer substance rather than as a photoconductive substance as conventionally known. It is especially superior in terms of sensitivity than the conventional one.

Various electrophotographic copying methods are known, and all of them include a step of light irradiation (image exposure).

This image exposure step selectively exposes the photoreceptor to make the photosensitive layer selectively conductive, but the photoreceptor of the present invention can be used in all conventional electrophotographic copying methods. Even when applied to the photoreceptor, various processes can be accomplished more effectively than conventionally known photoreceptors. In the photoreceptor of the present invention, the charge carrier generating pigment to be combined with the above-mentioned specific charge transfer substance does not need to be a specific one, and can be selected as appropriate.

As the charge carrier generating pigment, it is particularly effective to use, for example, the following azo pigments.

Azo pigments having a carbazole skeleton (for example, Japanese Patent Application No. 1983)
-874 yield is described in No. 52-8741) Azo pigments having a styrylstilbene skeleton (for example, Japanese Patent Application No. 52-488)
5) Azo pigments having a triphenylamine skeleton (for example, described in Japanese Patent Application No. 52-4581 Wani) Azo pigments having a dipenzothiophene skeleton (for example, described in Japanese Patent Application No. 52-4581 Wani)
86255) Azo pigments having an oxadiazole skeleton (e.g., described in Japanese Patent Application No. 77155/1982) Azo pigments having a fluorenone skeleton (e.g., Japanese Patent Application No. 1987-77155)
-87351) Azo pigments having a stilbene skeleton (for example, described in Japanese Patent Application No. 52-8179@) Azo pigments having a distyryl oxadiazole skeleton (for example, described in Japanese Patent Application No. 52-66711) Distyryl Azo pigments having a carbazole skeleton (for example, Japanese Patent Application No. 52-817)
In addition to these azo pigments, the following commonly known substances can also be used as charge carrier-generating pigments.

For example, inorganic pigments such as selenium, selenium-tellurium, cadmium sulfide, and cadmium-selenium sulfide; examples of organic pigments include CI Pigment Blue 25 (color index CI2ll8, also known as Diane Blue), CI Pigment Red 41 (CI2l2OO), and CI Pigment Red 41 (CI2l2OO); Azo pigments such as Drezed 52 (CI45lOO), CI Basic Cred 3 (CI452lO), phthalocyanine pigments such as CI Pigment Blue 16 (CI74lOO), such as CI Butt Brown 5
(Cl734lO), CI Battu Die (CI73O)
3O), indigo pigments such as Argo Scarlet B(
(manufactured by Bayer AG) and perylene pigments such as Indanthlen Scarlet R (manufactured by Bayer AG). The photoreceptor of the present invention is characterized by a combination of a charge transfer substance and a charge carrier generating pigment, and any layer structure that satisfies these conditions is included in the present invention. It is something that

For example, there are dispersed photoreceptors in which a photosensitive layer in which fine particles of a charge carrier generating pigment are dispersed in a charge transport medium is provided on a conductive support, and a thin layer of a charge carrier generating pigment (hereinafter referred to as a charge carrier generating layer). A photosensitive layer in which a charge transfer medium as described above is laminated in a layered manner (hereinafter referred to as a charge transfer layer) on a conductive support or a charge carrier generation layer is laminated in a layered manner on a charge transfer layer is formed on a conductive support. Examples include a laminated photoreceptor provided in the Figure 1 shows the former dispersion type electrophotographic photoreceptor.
2 and 3 show the latter laminated electrophotographic photoreceptor, respectively, in which 1 is a conductive support, 2 is a charge carrier generating pigment, 2'' is a charge carrier generating layer, and 3 is a charge transport medium. , 3'' is a charge transfer layer, and 4 is a photosensitive layer composed of a charge carrier generation pigment 2 (or charge carrier generation layer 2'') and a charge transfer medium 3 (or charge transfer layer 30).

As shown in FIGS. 2 and 3, in the case of a laminated photoreceptor, the charge transfer layer 3'' may be formed either above the charge carrier generation layer 2'' or below the charge carrier generation layer 2''. In consideration of mechanical strength and the like, it is generally preferable to place the former charge transfer layer 3'' on top.

In the case of a photoreceptor for dispersed electrophotography in which the charge carrier generating pigment 2 is dispersed in the charge transfer medium 3, the photoreceptor often has higher sensitivity when it is positively charged.

On the other hand, when considering a laminated photoreceptor, when it is located on the charge transfer layer 3'' or the charge carrier generation layer 2'',
Electrophotographic photoreceptors often have higher sensitivity when negatively charged, and when the charge transfer layer 3'' is located below the charge carrier generation layer 2'', the electrophotographic photoreceptor becomes positively charged. Charged materials often have higher sensitivity. Although the reasons for these are not clear, the above-mentioned specific compound (1●1-bis(4-N
This is thought to be because the charge transfer layer 3'' containing any one of -N-dibenzylaminophenyl)alkanes) plays a role in transporting holes.

In addition, photoconductivity generally refers to (1) generation of electric charge and
(2) It includes at least two phenomena of charge transfer. Therefore, the present invention utilizes the ability of the above-mentioned specific compound to transfer the charge generated by the charge carrier-generating pigment. However, it is also believed that this compound has the ability not only to simply transfer charges, but also to easily accept charges generated by the charge carrier-generating pigment. Binder resins used in the charge transport layer include many organic polymer compounds such as polyester, polyamide, polyurethane, polyketone, polycarbonate, vinyl polymer, etc., as well as poly-N-vinylcarbazole, which itself has photoconductivity. Polyvinylpyrene, polyvinylanthracene, polyvinylbenzocarbazole,
Pyrene-formaldehyde resin, bromopyrene-formaldehyde resin, etc. are also effective.

Examples of plasticizers include polychlorinated biphenyls, dibutyl phthalate, dimethylnaphthalene, and halogenated paraffins. To make an electrophotographic photoreceptor according to the present invention,
In the case of the dispersion-type photoreceptor shown in FIG. 1, a pigment dispersion is prepared by pulverizing the charge carrier-generating pigment with a suitable dispersion medium, such as tetrahydrofuran, by a grinding means such as a ball mill, and 1,1-bis( 4-NIN-dibenzylaminophenyl) alkanes, a suitable binder resin, and if necessary a suitable plasticizer are added and mixed to prepare a coating solution, or 1,1-bis(4-N-N -Dibenzylaminopheni) alkanes, a suitable binder resin and, if necessary, a suitable plasticizer are dissolved in a solvent such as tetrahydrofuran, a charge carrier generating pigment is further added thereto, and the mixture is ground and mixed using a grinding means such as a ball mill. A coating solution is prepared by applying this coating solution to a conductive support such as a metal plate such as aluminum, a plastic film coated with a metal such as aluminum, or paper that has been subjected to conductive treatment using a doctor blade or the like. Just apply it and then dry it.

In this case, 1,1-bis (4-N●
The ratio of N-dibenzylaminophenyl)alkanes is 1
It is 0 to 6% by volume, preferably 30 to 5% by volume.

The particle size of the charge carrier generating pigment 2 is about 5 microns or less in diameter, preferably 2 microns or less, and its proportion in the photosensitive layer 4 is 50% to 1% by weight, preferably 2% to 1% by weight. Weight%. Further, the thickness of the photosensitive layer 4 after drying is about 3 to 100 microns, preferably 5 to 3 microns.
It is 0 micron. In addition, in the case of the laminated type photoreceptor shown in FIG. 2, the charge carrier generating pigment layer 2'' is made of a charge carrier generating pigment alone, or if necessary, a charge carrier generating pigment layer 2'' is made of a mixture of a charge carrier generating pigment and a binder resin. Charge carrier generating pigment layer 2
'' is formed on the conductive support 1 by means such as vapor deposition or coating, and then 1.1 as a charge transfer substance is applied thereon.
A charge transfer layer 3'' containing -bis(4-N-N-dibenzylaminophenyl) alkanes may be formed by coating.

In addition, 1,1-bis (4-N-
The proportion of N-dibenzylaminophenyl) alkanes is
Considering the production conditions of the photoreceptor, 10 to 60% by weight
is appropriate. The thickness of this charge transfer layer 3'' is
5 to 100 microns is suitable. When forming the charge carrier generation layer of the multilayer photoreceptor by coating, the coating liquid is a pigment dispersion finely divided into particles of 5 microns or less, preferably 2 microns or less, by a grinding means such as a ball mill, together with an appropriate dispersion medium such as tetrahydrofuran. It may be applied by preparing a powder and applying it using a doctor blade or the like, or by dissolving it in a soluble solvent and applying it, and then drying it to precipitate it as fine crystals. In this case, when the charge carrier generating pigment layer 2'' is composed of a charge carrier generating pigment and a binder resin, it is preferable that the amount occupied by the binder resin is as small as possible in order not to impair photoconductivity. 5% by weight is preferable.Charge carrier generating pigment layer 2''
The thickness is 0.05 to 20 microns, preferably 0.1 to 20 microns.
It is 5 microns. Furthermore, in the case of the laminated type photoreceptor shown in FIG. 3, the layer structure is reversed between the charge carrier generating pigment layer 2'' and the charge transfer layer 3'' in the photoreceptor shown in FIG. The photoreceptor is prepared in a similar manner.

Further, on the conductive support 1 used in the present invention, a layer made of a resin such as polyamide, polyvinyl acetate, polyurethane, or a layer of aluminum oxide is applied to a thickness of 0.01 mm.
By providing a photosensitive layer after forming the photosensitive layer to a thickness of ~2 microns, it is possible to improve the adhesion between the conductive support and the photosensitive layer, and further improve the charging characteristics of the photoreceptor to some extent. can. The photoreceptor according to the present invention produced in this way can fully satisfy the objectives of the present invention, such as (a) high sensitivity and (l) low fatigue due to repeated charging and exposure. be.

Examples are shown below.

In the text, all parts are by weight. Example 1 One part of tetrahydrofuran was added to two parts of Diane Blue (CI2ll8O), and the mixture was pulverized and mixed in a ball mill to obtain a charge carrier-generating pigment dispersion.

This was applied using a doctor blade onto a polyester film deposited with aluminum, and dried naturally to a thickness of 1.
A charge carrier generation layer of μ is formed. Next, a charge transport layer obtained by mixing 2 parts of 1◆1-bis(4-N-N-dibenzylaminophenyl)propane represented by the structural formula, 3 parts of polycarbonate (Teijin Panlite L), and 45 parts of tetrahydrofuran. The forming liquid was applied onto the above charge carrier generation layer using a doctor blade, and dried at 1000 C for 1 hour to form a charge transfer layer with a thickness of 9 μm, thereby producing a photoreceptor of the present invention.

This photoreceptor was negatively charged by performing corona discharge for 208 minutes using an electrostatic copying paper testing device 0 The surface potential VpO (V) at that time was measured, and then the surface was irradiated with light using a tungsten lamp at an illumination intensity of 20 lux, and the surface potential was VpO (V).
Find the time (seconds) until the pO reaches 112 and calculate the exposure amount E.
ll2 (lux-seconds) was obtained.

The result is VPO=-1180V1E112=11.7
Looks and seconds. The liquid of Example 2 is pulverized and mixed in a ball mill to obtain a charge carrier-generating pigment dispersion.

This was applied onto a polyester film deposited with aluminum using a doctor blade, and dried for 5 minutes in an oven at 80° C. to form a charge carrier generation layer with a thickness of 1 μm. Next, 1,1-bis(4-N-
A charge transfer layer forming liquid obtained by mixing 2 parts of N-dibenzylaminophenyl) propane, 3 parts of polycarbonate (Panlite L) and 45 parts of tetrahydrofuran was applied onto the above charge carrier generation layer using a doctor blade. ,1
The photoreceptor of the present invention was prepared by drying the powder at 00° C. to form a charge transfer layer with a thickness of 10 μm.

This photoreceptor was negatively charged in the same manner as in Example 1, and ■PO, . When E'2 was measured, VpO=-14
40V. ．． E1 no 2 = 9.3 lux seconds.

Example 3 In the same manner as in Example 2, the charge carrier generating pigment and the charge transfer agent were used, and VpO=-920V, . E112=3
．． It was 0 lux seconds.

Example 4 In the same manner as in Example 2, the pigment was used as a charge carrier generating pigment and as the charge transfer agent. VPO=-940■, Ell2=9.
It was 0 lux seconds.

Example 5 The photoreceptors obtained in Examples 1 to 4 were negatively charged using a commercially available copying machine, and then light was irradiated through the original image to form an electrostatic latent image, followed by dry development with positively charged toner. The image was developed using a chemical agent, and the image was electrostatically transferred to high-quality paper and fixed to obtain a clear image.

A similarly clear image was obtained when a wet type developer was used as the developer. Example 6 Selenium was deposited to a thickness of 1 on an aluminum plate approximately 300μ thick.
A charge carrier generation layer is formed by vacuum deposition on μ.

2 parts of the compound represented by: polyester resin (manufactured by DuPont, Polyester Adhesive 49000)
3 parts of tetrahydrofuran and 45 parts of tetrahydrofuran were mixed to prepare a charge transfer layer forming liquid, and this was applied onto the charge carrier generation layer (selenium vapor deposition layer) using a doctor blade, air-dried, and then dried under reduced pressure. A charge transfer layer having a thickness of 10p was formed in this manner to obtain a photoreceptor of the present invention.

This photoreceptor was used in the same manner as in Example 1, and VpO and Ell2 were measured. VpO=-1460V. ．．
E112 = 6.2 lux ● seconds. Example 7 Instead of selenium in Example 6, a perylene pigment was vacuum deposited to a thickness of 0.3 μm to form a charge carrier generation layer.

Next, a photoreceptor was prepared in the same manner as in Example 6 except that the charge transfer agent was changed to ■PO=-1120V. ．． E11
It was 2 = &4 looks ● seconds.

Example 8 The photoreceptors obtained in Examples 6 and 7 were negatively charged using a commercially available copying machine, and then light was irradiated through the original image to form an electrostatic latent image, followed by dry development with positively charged toner. The image was developed using a chemical agent, and the image was electrostatically transferred to high-quality paper and fixed to obtain a clear image.

A similarly clear image was obtained when a wet type developer was used as the developer. Example 9 1 part of Chlordiane blue to 158 parts of tetrahydrofuran
After grinding and mixing the mixture in a ball mill,
A photosensitive layer forming liquid obtained by adding 18 parts of 12 m1 polyester resin (Polyester Adhesive 49000) and further mixing was applied onto an aluminum vapor-deposited polyester film using a doctor blade. The powder was dried to form a photosensitive layer having a thickness of 16 μm, thereby producing the photoreceptor of the present invention.

This photoreceptor was positively charged by +■■ corona discharge using the same device as used in Example 1, and VpO and Ell2 were similarly measured.
It was 1080 volts, Ell2 = 5.4 look gates ● seconds.

Example 10 In the same manner as in Example 9, the pigment was used as a charge carrier generating pigment and the charge transfer agent was used. As a result, VpO=1340V, . E112=9
．． It was hot in 6 looks ● seconds.

Example 11 In the same manner as in Example 9, a charge carrier-generating pigment and a ladder were used, and as a charge transfer agent, ■PO=1450■, Ell2=11
．． It was 4 lux seconds.

Example 12 In the same manner as in Example 9, a charge carrier-generating pigment and a ladder were used, and a charge transfer agent was used. VpO=940V, . E112=9.
It was hot in 2 looks ● seconds.

Example 13 The photoreceptors obtained in Examples 9 to 12 were positively charged using a commercially available copying machine, and then light was irradiated through the original image to form an electrostatic latent image, followed by dry development with negatively charged toner. The image was developed using a chemical agent, and the image was electrostatically transferred to high-quality paper and fixed to obtain a clear image.

A similarly clear image was obtained when a wet type developer was used as the developer. Comparative Example In order to confirm the effect of the present invention, Example 1 was prepared as a comparative example.
In order to provide a charge carrier generation layer on a conductive support,
・1-bis(4-N-N-dibenzylaminophenyl)
When a photoreceptor with only a layer containing propane was charged using the same device as in Example 1, VPO=-980VE112=8
0 lux・sec or more VPO=+1080VE112=8
0 lux·sec or more, and the photoconductivity is extremely low for both positive and negative charges.
It is clear that N-dibenzylaminophenyl) alkanes act as charge transfer substances.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a dispersion type photoreceptor according to the present invention, and FIG.
3 are enlarged cross-sectional views of the laminated photoreceptor according to the present invention. DESCRIPTION OF SYMBOLS 1... Conductive support, 2... Charge carrier generating pigment, 2''... Charge carrier generating pigment layer, 3.
...Charge transfer medium, 3''...Charge transfer layer, 4...Photosensitive layer.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor in which a photosensitive layer containing a charge carrier generating pigment and a charge transfer substance is provided on a conductive support, wherein the charge transfer substance is represented by the following general formula: 1. An electrophotographic photoreceptor comprising at least one compound of ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, in the general formula, R_1 represents an alkyl group having 1 to 11 carbon atoms, and R_2 represents hydrogen, methyl group, nitro group, or halogen.)