JPH04171454A - Sensitized body for electrophotography - Google Patents

Abstract

PURPOSE:To improve the reproducibility of both red and blue colors by containing a specific bis-azo compound and a specific polycyclic quinone compound in such a way that its weight mixture ratio is within a specific range. CONSTITUTION:An electric charge generating layer 2 contains at least one kind of bis-azo compound expressed by a formula I and at least one kind of polycyclic quinone compound expressed by a formula II as electric charge generating material in such a way that a weight mixture ratio between the bis-azo compound and the polycyclic quinone compound is within a range of 0.5:9.5 - 1.3:8.7. In the formula I, R1 is a halogen atom, an alkoxyl group, or the like; R2 is a substitutional alkyl group; R3 is a hydrogen atom, an acyl group, or the like; R4 represents either one of a hydrogen atom, an alkoxyl group and the like. In the formula II, X represents either one of a halogen atom and a carboxyl group. This results in obtaining a sensitized body provided with uniform photosensitivity across the whole visual light region and excellent in the reproducibility of both red and blue colors.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to a photosensitive layer comprising a conductive substrate, a charge generation layer, and a charge transport layer. Equipped with an electrophotographic printer? ,! This invention relates to an organic laminated electrophotographic photoreceptor used in photographic machines and the like.

[Conventional technology]

Conventionally, the photosensitive layer used in electrophotographic photoreceptors consists of vacuum-deposited inorganic photoconductive substances such as selenium, or inorganic photoconductive substances such as zinc oxide or cadmium sulfide dispersed in a resin binder. Organic photoconductive materials such as PVK, phthalonanine compounds, or bisazo compounds are dispersed in a binder resin or vacuum-deposited.

The functions of an electrophotographic photoreceptor include the function of receiving light and generating charges, and the function of receiving light and transporting charges. Conventional electrophotographic photoreceptors include single-layer photoreceptors, which have the above functions in the same layer, and laminated photoreceptors, which have these functions separated into each layer.The latter type has excellent practical sensitivity. ing.

For example, the Carlson method is applied to image formation by electrophotography using this type of photoreceptor. In this electrophotographic process, the photoreceptor is charged by corona discharge in a dark place, and the charged photoreceptor is charged by corona discharge. This process is performed by forming an electrostatic latent image such as characters or pictures on a document by exposing the body surface to light, developing the formed electrostatic latent image with toner, transferring the developed toner image to a support such as paper, and fixing it. After the toner has been transferred, the photoreceptor is subjected to static neutralization, residual toner removal, optical static neutralization, etc., and is then reused.

In order for a photoreceptor to be put to practical use in the above-mentioned image forming process, it must have a certain level of photosensitivity, charge acceptance ability, i! It has excellent electrical and photoelectric properties such as load holding capacity, residual potential, and repetition stability, as well as mechanical strength such as abrasion resistance and hardness, and heat resistance.

i1 It must also be excellent in terms of humidity, durability against light and ozone, etc.

Organic photosensitive materials have flexibility, thermal stability, material diversity,
Although it has many advantages such as film-forming properties, it has problems such as photosensitivity, mechanical strength, and durability against light and ozone. For this purpose, organic photoreceptors using organic materials take advantage of the film-forming properties of f-organic materials and the diversity of materials to create charge-generating layers,
It is a laminated type consisting of functionally separated layers such as a charge transport layer.
Development and practical application are progressing by selecting materials suitable for each layer and using them in combination.

When copying an original, it is desirable to obtain a copied image that faithfully reproduces the image density of the original, but to achieve this, it is required that the photosensitivity used in the copying machine be uniform over the entire visible light range. However, photosensitivity varies depending on the wavelength of light depending on the charge generating material used in the photoreceptor.

For example, for phthalonanine compounds, the wavelength is 600 nm to 7
It exhibits extremely high photosensitivity in the red light region of 00 nm. Furthermore, zinc oxide has a light absorption maximum in the wavelength range of 37 flnm to 390 nm, and has high photosensitivity in the near ultraviolet region. In a copying machine equipped with a photoreceptor whose charge-generating material is a photoconductive material that exhibits extremely high photosensitivity in such a specific light wavelength region, practical problems occur when copying originals.

For example, in a copying machine equipped with a photoreceptor that uses copper phthalocyanine as a charge-generating substance, when the photoreceptor is charged and exposed to light, the maximum absorption of light occurs in the light wavelength range of 600 nm to 700 nm, as described above, so red light is produced. Shows high photosensitivity. Therefore, when exposed through an original having red and blue images, the red image is less likely to be reproduced in the copied image than the blue image. This means that the photoreceptor is strongly sensitive to the red reflected light from the red image on the original, and the surface potential of this area is greatly attenuated to the same extent as the attenuation for the reflected light from the white area of the original, and in the developing process. This is because it becomes difficult for toner to adhere. In a copying machine equipped with a photoconductor that uses zinc oxide as a photosensitive material, the relationship between white light and blue light is the same as the relationship between white light and red light in copper phthalocyanine, and the blue image of the original is displayed on the copied image. becomes difficult to reproduce.

In order to eliminate this drawback, it is known to add a suitable dye to a photoconductive substance to produce a photosensitive material. For example, Japanese Patent Application Laid-Open No. 53-37423 describes an example of adding a dye to a photoconductive material of a single-layer type photoreceptor by dispersing a dye having an absorption maximum in the light wavelength range of 400 nm to 600 nm in β-type phthalocyanine. There is a description of forming a layer, and in JP-A-57-14848, as an example of adding a dye to the charge transport layer of a laminated photoreceptor, there is a description of forming a layer on the light irradiation side of a charge generation layer containing a phthalo/anine compound. There is a description that a photosensitive layer is formed by dispersing a dye having a light absorption maximum in the red light region in a charge transport layer. In addition, an example of a photoreceptor in which fluorescein or the like is dispersed and contained in zinc oxide as a photoconductive substance is ``Electronic Photography'', edited and translated by Hide Inoue, pp. 224-22.
5 pages (published by Kyoritsu Shuppan in 1973) [original R1M, 5ch
by Affert rE] electrophotograph
y” (published by Focal Press in 1955)].

[Problem to be solved by the invention]

However, in these known methods, dyes with relatively low electrical resistance are dispersed and contained throughout the photoconductive layer or throughout the charge transport layer that is supposed to maintain the surface potential. There were some drawbacks. Furthermore, there is a drawback in that the durability of the photoreceptor is poor when the photoreceptor is used repeatedly in a copying machine, and this is mainly caused by the gradual deterioration of the dye contained therein. The main cause of dye deterioration is the decomposition of dyes by ozone generated during the charging, copying, and static elimination processes, and by light during exposure and optical static elimination processes.

As the dye decomposes over time, the effect of adding the dye to the photosensitive material decreases, and the uniformity of the light wavelength sensitivity of the photoreceptor deteriorates. Further, the decomposed dye adversely affects the photosensitive material containing the original dye dispersed therein as an impurity, causing a decrease in the surface potential and photosensitivity of the photoreceptor and an increase in the residual potential. Furthermore, if the layer containing the dye is located on the surface of the photoreceptor, decomposition may proceed easily due to light or ozone from the surface, and if the dye is contained dispersedly in the photosensitive material, the dye may decompose. This is not preferable because the influence of the product directly affects the entire area of the dispersed photosensitive material.

The present inventor uses a bisazo compound as a charge generating material sensitive to red light, but the light wavelength is 630r+m~65
Since it has a light absorption maximum in the 0r++n region, it has better red reproducibility than the above-mentioned phthalonanine compound, but satisfactory spectral characteristics were not obtained.

In order to reproduce red well, it is possible to use a filter to cut out long wavelength light, but this results in a decrease in sensitivity and also
This is not preferable because it also increases the cost of the copying machine.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide an electrophotographic photoreceptor that has various photosensitivity over the entire visible light range and has excellent red reproducibility and blue reproducibility. The task is to

[Means to solve the problem]

According to the present invention, the above problem is solved by comprising a photosensitive layer formed by laminating at least two layers, a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance, on a conductive substrate. In the electrophotographic photoreceptor, the charge generation layer contains at least one bisazo compound represented by the following general formula (A) and at least one polycyclic quinone compound represented by the following general formula (B) as a charge generation substance. This problem is solved by providing an electrophotographic photoreceptor containing a bisazo compound and a polycyclic quinone compound in a weight mixing ratio of 0.5:9.5 to 1.3:8.7. Ru.

In formula (A), R is a halogen atom or an alkyl group.

Represents any of the alkokyne groups, R represents an optionally substituted alkyl group, and R3 is a hydrogen atom, a cyano group, a carbamoyl group, or a carboxyl group.

It represents either an ester group or an acyl group, and R1 represents any one of a hydrogen atom, a halogen atom, a nitro group, an alkyl group, and an alkoxy group. ] [2 (B) Middle, X
represents any one of a halogen atom, a nitro group, an ano group, an acyl group, and a carboxyl group, and n represents any integer from O to 4. ] The weight mixing ratio of the bisazo compound and the polycyclic quinone compound is 0.
．． More preferably, the ratio is within the range of 75.9.25 to 1:9.

The charge generation layer and the charge transport layer in the photosensitive layer may be stacked in the order in which the charge transport layer is stacked on top of the charge generation layer, or in the reverse order.

Specific compounds used as charge generating substances include a bisazo compound represented by the following formula (/l-1) and a bisazo compound represented by the following formula (B
It is preferable to use the polycyclic quinone compound represented by -1).

Specific examples of the bisazo compound shown in formula (A) used in the present invention are as follows.

Further, specific examples of the polycyclic quinone compound represented by the above-mentioned formula (B) include the following.

[Effect]

In the charge generation layer, as a charge generation substance, the -ritual (Δ)
By mixing the bisazo compound represented by and the polycyclic quinone compound represented by formula (B) above at a weight mixing ratio of Q within the range of 5:9.5 to 13.8.7, red color can be produced. It is possible to obtain an electrophotographic photoreceptor that has excellent reproducibility and blue reproducibility and has substantially uniform photosensitivity over the entire visible light range. It is more preferable that the weight mixing ratio of the bisazo compound and the polycyclic quinone compound is within the range of 0.75:9.25 to 1:9. The order in which the charge generation layer and charge transport layer are stacked in the photosensitive layer is such that whether the charge transport layer is stacked on top of the charge generation layer or vice versa, the photosensitivity will be improved because the charge polarity of the photoreceptor will be reversed. There is no difference in this respect.

〔Example〕

FIG. 1 is a conceptual cross-sectional view showing an embodiment of the photoreceptor of the present invention, in which a charge generation layer 2 is formed on a conductive substrate 1. A negatively charged photoreceptor is shown which includes a photoreceptor layer 4a in which charge transport layers 3 are sequentially laminated.

The conductive substrate 1 is made of copper, aluminum, or nickel.

Metal materials such as indium and gold, or plastic pieces coated with these metal materials can be used. Since these are mainly used in a cylindrical shape and serve as a support for other layers, they preferably have sufficient strength for handling.

The charge generation layer 2 includes the above-mentioned -ritual (Δ) as a charge generation material.
Using photoconductive particles that are a mixture of a bisazo compound represented by and a polycyclic quinone compound represented by formula (B),
Prepolymer of diallyl phthalate, polycarbonate as resin binder.

A coating solution using polyester, polyurethane, methacrylic acid ester polymers and copolymers, etc., alone or in combination, and well dispersed and dissolved in an organic solvent such as methyl ethyl ketone using a sand mill, ultrasonic homogenizer, ball mill, etc. It is formed by coating and drying so that the film thickness after drying is 0.2 μm to 2.0 μm.

The charge transport layer 3 uses a derivative such as pyrazoline, triphenylmethane, styryl, oxadiazole, or hydrazone as a charge transport substance, and a polymer or copolymer of polycarbonate, polyarylate, polyester, polyurethane, or methacrylate as a resin binder. The film thickness after drying is 10 μm to 25 μm by using a coating solution in which these are dissolved in an organic solvent, either singly or in combination.
It is coated and dried to form a shape of m.

As a charge generating substance, a material obtained by mixing a bisazo compound represented by the compound (A-1) and a polycyclic quinone compound represented by the compound (B-1) at each weight mixing ratio shown in Table 1 is used, For the others, use the materials and methods described above.
Each photoreceptor having the configuration shown in the figure was produced.

/-'' / / Table 1 These photoconductors were installed in a commercially available copying machine that uses an organic negatively charged photoconductor with the exposure wavelength cut filter removed, and the color reproducibility was evaluated using Macbeth's Macbeth. The color reproducibility of blue and red was evaluated by copy density using a densitometer RD-914.

The results are shown in FIG. In FIG. 3, the vertical axis is copy density, and the horizontal axis is compound (A-1) and compound (B, -,
, -1).

As can be clearly seen from Figure 3, as the mixing ratio of compound (B-1) increases, the reproducibility of red color improves, but the reproducibility of blue color tends to deteriorate. It can be seen that by adjusting the mixing ratio of the bisazo compound and the compound (B-1), that is, the polycyclic quinone compound, within an appropriate range, a photoreceptor with excellent red reproducibility and blue reproducibility can be obtained.

A good mixing ratio range is 0.5:9.5 to 1.3:8.7 for the bisazo compound and polycyclic quinone compound, more preferably 0.75:9.25 to 1.0. :
It is within the range of 9.0.

FIG. 2 is a conceptual cross-sectional view of a different embodiment of the photoreceptor of the present invention, in which a charge transport E3° charge generation layer 2 is provided on a conductive substrate 1.
This shows a positively charged photoreceptor including a photoreceptor layer 4b laminated in this order. In this case, in order to protect the charge generation layer 2,
It is common to further provide a protective layer 5. There is no fundamental difference in the function of the charge generation layer in a photoconductor with this structure from that of the photoconductor shown in Figure 1, and bisazo compounds and polycyclic quinone compounds are appropriately used as charge generation substances in the charge generation layer. By using materials mixed at a similar weight mixing ratio, a photoreceptor with excellent red reproducibility and blue reproducibility can be obtained.

Further, even if the photosensitive layer is provided with various layers such as an intermediate layer between the charge generation layer and the charge transport layer, the function of the charge generation layer remains essentially the same, and the present invention is similar. It is effective for

〔Effect of the invention〕

According to the present invention, in the organic layered photoreceptor, the charge generation layer contains at least one of the bisazo compounds represented by the above-mentioned -Funzo (A) and the above-mentioned -Funazo (B). and at least one of the polycyclic quinone compounds shown in a weight mixing ratio of 0.5:9.5 to 1:I
:87, it is possible to achieve good photosensitivity over the entire visible light range (2) and to obtain a photoreceptor with excellent red reproducibility and blue reproducibility (5). The weight mixing ratio of both is 0.75:9.25 to 1
．． When the ratio is within the range of 0:9.0, the reproducibility of red and blue colors becomes more uniform, which is more preferable. This effect depends on the stacking order of the charge generation layer and charge transport layer in the photosensitive layer.
Further, the same applies when layers other than these two layers are laminated.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 and 2 are conceptual cross-sectional views of different embodiments of the photoreceptor of the present invention, and FIG. 3 is red and blue copy density and charge generation of the photoreceptor of the present invention. It is a diagram showing the relationship between the weight mixing ratio of compound (A-1) and compound (B-1) as substances. 1 conductive substrate, 2 charge generation layer, 3 charge transport layer, 4
a, 4b photosensitive layer, 5 protective layer. Figure 2 Figure 3

Claims (1)

[Claims] 1) Electrophotography comprising a photosensitive layer formed by laminating at least two layers, a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance, on a conductive substrate. In the photoreceptor, the charge generation layer contains at least one bisazo compound represented by the following general formula (A) and at least one polycyclic quinone compound represented by the following general formula (B) as a charge generation substance. The weight mixing ratio of the bisazo compound and the polycyclic quinone compound is 0.5:9.5 to 1.3:8
．． 7. A photoreceptor for electrophotography, characterized in that the content falls within the range of 7. ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(A) [In formula (A), R_1 represents a halogen atom, an alkyl group, or an alkoxy group, and R_2 is an optionally substituted alkyl group. R_3 represents a hydrogen atom, a cyano group, a carbamoyl group, a carboxyl group, an ester group, or an acyl group, and R_4 represents a hydrogen atom, a halogen atom, a nitro group, an alkyl group, or an alkoxy group. Represents either. ]▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(B) [In formula (B), X represents any one of a halogen atom, nitro group, cyano group, acyl group, and carboxyl group,
n represents any integer from 0 to 4. 2) The electrophotographic photoreceptor according to claim 1, wherein the weight mixing ratio of the bisazo compound and the polycyclic quinone compound is within the range of 0.75:9.25 to 1:9. 3) The electrophotographic photoreceptor according to claim 1 or 2, comprising a photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order on a conductive substrate. 4) The electrophotographic photoreceptor according to claim 1 or 2, comprising a photosensitive layer in which a charge transport layer and a charge generation layer are laminated in this order on a conductive substrate. 5) Any one of claims 1, 2, 3, and 4, characterized in that a bisazo compound represented by the following formula (A-1) and a polycyclic quinone compound represented by the following formula (B-1) are used. The electrophotographic photoreceptor described above. ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(A-1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(B-1)