JP2712372B2 - Photoconductor and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to a photoreceptor in which a photoconductive material is dispersed in a binder resin in an amorphous form. Further, the present invention relates to a method for manufacturing the photoconductor.

2. Description of the Related Art In recent years, electrophotographic photosensitive members in which an organic photoconductive material is blended in a binder resin have been widely used.

Conventionally, when an organic photoconductive material is blended into a binder resin, the organic photoconductive material and the binder resin are mixed in an appropriate solvent and then immediately dispersed by an appropriate means such as a ball mill to prepare a photosensitive coating solution. It was done by doing.
As a technique for dispersing and stabilizing an organic photoconductive material in a photosensitive coating solution, for example, Japanese Patent Application Laid-Open No. Sho 60-178456 is known.

However, some organic photoconductive materials crystallize in a photoconductive layer resin formed by applying and drying a photosensitive coating solution. Some of the same organic photoconductive materials have different crystalline states depending on the manufacturing method. In such materials, some amorphous materials are highly sensitive and their characteristics vary depending on the crystal state. Therefore, it is necessary to control the crystal state. However, manufacturing methods for effectively controlling the crystal state have been known. Had not been.

Problems to be Solved by the Invention It is an object of the present invention to solve the above-mentioned problems, and to provide a photoconductor in which an organic photoconductive material exists in an amorphous state in a photosensitive layer.

Still another object of the present invention is to provide a method for producing a photoconductor in which an organic photoconductive material is uniformly dispersed in a resin of a photosensitive layer.

Means for Solving the Problems The present invention uses an azo pigment which has high sensitivity in an amorphous state as an organic photoconductive material and is easily crystallized by mixing a binder resin and a solvent. After performing a crystallization preventing treatment in which the resin solution is immersed in a resin solution having a concentration of 3% by weight or more for 5 hours or more, the resin solution having been subjected to the dispersion adjusting treatment is applied and dried to substantially reduce the azo pigment. The present invention relates to a photoconductor having a binder resin layer dispersed in a crystalline state.

Further, the present invention uses an azo pigment as an organic photoconductive material which has a high sensitivity in an amorphous state and is easily crystallized by mixing a binder resin and a solvent, and the azo pigment has a concentration of 3% by weight or more. A crystallization-preventing treatment step of dipping in the resin solution for 5 hours or more, a step of dispersing and adjusting the resin solution for coating, and a step of coating and drying the resin solution for coating, whereby the azo pigment is contained in the binder resin. Forming a photosensitive layer bound in a substantially amorphous state.

The present invention is applied to a case where a photoconductive material which shows high sensitivity in an amorphous state and is easily crystallized in a photosensitive layer formed by a usual method is used.

The usual method is to form a photosensitive coating liquid obtained by mixing an azo organic photoconductive material and a binder resin in an appropriate solvent and then dispersing the mixture by an appropriate means such as a ball mill, followed by drying. The crystalline state is determined by X-ray diffraction of the photosensitive layer by the intensity of the diffraction peak. That is, the azo-based organic photoconductive material is easily crystallized, and the azo-based organic photoconductive material-dispersed resin obtained by adding 20 g of the azo-based organic photoconductive material to 960 g of cyclohexanone and dispersing it with, for example, a sand grinder for 24 hours. The resin film obtained by applying and drying the solution is subjected to X-ray diffraction and a diffraction peak due to the azo-based organic photoconductive material is observed.

Examples of such azo-based organic photoconductive materials include pigments such as styryl-based bisazo-based pigments.

When a photosensitive layer is formed by a usual method using the above-mentioned azo-based organic photoconductive material, a crystal is formed by X-ray diffraction. According to the production method of the present invention, a crystal system is formed by X-ray diffraction. Substantially not observed. This indicates that the azo organic photoconductive material is present in the photosensitive layer in an amorphous state. Therefore, as is clear from the examples described later, the photoreceptor obtained according to the method for producing a photosensitive layer of the present invention has good sensitivity. Here, that the crystal system is not substantially observed means that a diffraction peak obtained by synthesizing scattered waves of atoms in the substance is not observed in the crystal structure.

It should be further noted that the absorption spectrum of an azo organic photoconductive material dispersed in a binder resin such that crystallization is not observed by X-ray diffraction is shifted to shorter wavelengths. This fact indicates that it is effective for improving red reproducibility, for example.

In order to form the azo organic photoconductive material according to the present invention so that the azo organic photoconductive material is not substantially crystallized in the photosensitive layer, first, the azo organic photoconductive material is dissolved in a resin solution having a concentration of 3% by weight or more. Soak for 5 hours or more.

Examples of resins that can be used for the resin solution include polyester, polyvinyl butyral, polyamide, formal,
Methacryl, acrylic, polystyrene, phenoxy, polyvinyl chloride and the like, as a solvent, cyclohexanone, trichloroethane, dichloromethane, toluene,
Xylene, tetrahydrofuran, dioxane, methyl ethyl ketone and the like can be used, and the concentration thereof is preferably as high as possible, but usually the resin is 3% by weight or more, preferably 5% by weight or more, more preferably 10% by weight of the resin solution.
It is.

An azo organic photoconductive material is added to the above resin solution
0.5-300 wt%, preferably 10-200 wt%, more preferably 30-150 wt%, added for at least 5 hours or more,
Preferably, it is immersed for 10 hours or more. If these conditions are not satisfied, the desired effects of the present invention will not be sufficiently achieved.

The azo-based organic photoconductive material immersion resin solution obtained as described above is preferably further added with a solvent for ease of dispersion treatment, and sufficiently dispersed by a sand grinder, a ball mill, or the like according to an ordinary method. To form a photosensitive layer.

The photosensitive layer may be a single-layer photosensitive layer in which an azo organic photoconductive material, a charge transport material and other desired additives are mixed in a binder resin, or may be separated into a charge generation layer and a charge transport layer. Function-dispersed type photosensitive layer,
The photosensitive layer is not particularly limited, and may be a known type of photosensitive layer.

 Hereinafter, the present invention will be described with reference to examples.

Example 1 (Preparation of Sample 1) In a binder solution having a solid content of 5% by weight in which 20 g of a polyester resin (Vylon 200; manufactured by Toyobo Co., Ltd.) was dissolved in 380 g of cyclohexanone, the following structural formula [A]; 20 g of distyrylpyridazine carbazole pigment represented by
For 12 hours.

Next, 580 g of cyclohexanone was added to the above solution to add
Time dispersion was performed.

The dispersion solution obtained as described above is referred to as Sample 1.

(Measurement of Absorption Spectra) The absorption spectrum of the resin film obtained by applying, drying and peeling Sample 1 on a glass substrate was measured in the wavelength range of 400 to 800 nm. The maximum absorption wavelength (λ ₀ ) was 584 nm. The measurement results of the absorption spectrum are shown in FIG.

(Measurement of X-ray diffraction spectrum) Sample 1 was applied on a glass substrate and dried to prepare a sample for X-ray diffraction, and the X-ray diffraction spectrum was measured. The results obtained are shown in FIG.

FIG. 2 shows no peak, indicating that the pigment [A] is dispersed in the polyester binder resin in an amorphous state.

(Preparation of Photoreceptor) The dispersion of Sample 1 was coated on an aluminum substrate and dried to form a 0.2 μm-thick charge generation layer.

Next, the following structural formula [B]; 3 parts by weight of a butadiene compound represented by the formula and 3 parts by weight of a polycarbonate resin are dissolved in 20 parts by weight of dichloromethane, and this solution is applied on the above-mentioned charge generating layer so as to have a dry film thickness of 20 μm and dried to form a charge transporting layer. Was formed. As described above, a photoreceptor comprising two layers, a charge generation layer and a charge transport layer, was obtained.

The obtained photoreceptor is incorporated in a commercially available electrophotographic copying machine (EP-4702, manufactured by Minolta Camera Co., Ltd.), and the initial surface potential (V ₀ )
Exposure (E1 / 2) (lux-se
When c) was measured, it was 1.4 lux · sec.

Comparative Example 1 In a binder solution in which 20 g of a polyester resin was dissolved in 960 g of cyclohexanone, 20 g of a distyrylpyridazine carbazole pigment represented by the structural formula [A] used in Example 1 was charged and dispersed for 24 hours.

The dispersion solution obtained as described above is referred to as Sample 2.

Except for using Sample 2, the absorption spectrum and the X-ray diffraction spectrum were measured in the same manner as in Example 1. The results are shown in FIGS. 1 and 3, respectively. Example 1
A photoreceptor was prepared and evaluated in the same manner as described above.

FIG. 3 shows that the Bragg angle (2
θ) shows a peak at 16.6 degrees, which indicates that the pigment [A] forms some crystal system in the polyester resin binder resin.

The λ ₀ is 676nm, E1 / 2 was 6.6lux · sec.

Example 2 The following structural formula [C] is used in place of the distyrylpyridazine carbazole pigment of structural formula [A]; A dispersion solution was prepared in the same manner as in the preparation of Sample 1 of Example 1, except that the distyrylpyridazine naphthol AS pigment represented by the following formula was used. The resulting dispersion is designated as Sample 3.

Except for using Sample 3, the absorption spectrum and the X-ray diffraction spectrum were measured in the same manner as in Example 1. Further, a photosensitive member was prepared and evaluated in the same manner as in Example 1. As a result, no diffraction peak was observed in X-ray diffraction.

The λ ₀ is 555nm, E1 / 2 was 2.0lux · sec.

Comparative Example 2 In the same manner as in the preparation of Sample 1 of Comparative Example 1, except that the distyrylpyridazine naphthol AS pigment represented by the above structural formula [C] was used instead of the distyrylpyridazine carbazole pigment of the structural formula [A]. A dispersion solution was prepared. The resulting dispersion is designated as Sample 4.

Except for using Sample 4, the absorption spectrum and the X-ray diffraction spectrum were measured in the same manner as in Example 1. Further, a photoreceptor was prepared and evaluated in the same manner as in Example 1. As a result, a clear diffraction peak was observed in X-ray diffraction.

The λ ₀ is 587nm, E1 / 2 was 4.0lux · sec.

Effects of the Invention The photoreceptor obtained according to the present invention has good sensitivity and improved red reproducibility.

[Brief description of the drawings]

FIG. 1 is a view showing a visible light absorption spectrum of an azo organic photoconductive material. FIG. 2 and FIG. 3 are diagrams showing X-ray diffraction spectra of an azo organic photoconductive material dispersed in a binder resin.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masakazu Takada 2-30-30 Azuchicho, Higashi-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Camera Co., Ltd. (72) Yuki Shimada 2--30 Azuchicho, Higashi-ku, Osaka, Osaka Address Osaka International Building Minolta Camera Co., Ltd. (56) References JP-A-61-151659 (JP, A) JP-A-59-81647 (JP, A)

Claims (2)

(57) [Claims] An azo pigment having high sensitivity in an amorphous state and being easily crystallized by mixing a binder resin and a solvent is used as an organic photoconductive material, and the azo pigment has a concentration of 3% by weight or more. This azo pigment is dispersed in a substantially amorphous state by performing a crystallization prevention treatment of dipping in a resin solution of 5 hours or more, and then applying and drying the resin solution that has been subjected to the dispersion adjustment treatment. A photoconductor having a binder resin layer formed thereon. 2. An organic photoconductive material, which is an azo pigment which has a high sensitivity in an amorphous state and is easily crystallized by mixing a binder resin and a solvent, and the azo pigment has a concentration of 3% by weight or more. A crystallization-preventing treatment step of dipping in the resin solution for 5 hours or more, a step of dispersing and adjusting the resin solution for coating, and a step of coating and drying the resin solution for coating, whereby the azo pigment is contained in the binder resin. Forming a photosensitive layer bound substantially in an amorphous state.