JP3239676B2 - Manufacturing method of photoreceptor for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electrophotographic photoreceptor, and more particularly to a method of manufacturing a photoreceptor for electrophotography, in which a charge generation layer and a charge transport layer contain an organic material and are used in electrophotographic printers and copiers. The present invention relates to a method for manufacturing a photoconductor for electrophotography.

[0002]

2. Description of the Related Art In recent years, organic photoconductors have been widely used for laser beam printers and copiers.
Research on organic photoconductive substances has been promoted as the photosensitive material. A photoreceptor using an organic photoconductive substance has higher flexibility, thermal stability, film forming property, transparency, and transparency than those using a conventional inorganic photoconductive substance such as selenium.
Although there is an advantage in terms of price and the like, it is inferior to the case of using an inorganic photoconductive substance in terms of dark resistance and light sensitivity. Therefore, taking advantage of the advantage of easy film formation, the photosensitive layer of the photoreceptor is functionally separated into a layer that mainly contributes to charge generation and a layer that contributes to surface charge retention in dark places and charge transport during photoreception. A laminated structure has been devised, and a structure in which the electrophotographic characteristics are improved as a whole by selecting a material suitable for the function of each layer is now mainstream.

[0003] This type of laminated photoreceptor usually has a structure in which a charge generating layer containing an organic charge generating substance and a charge transporting layer containing an organic charge transporting substance are formed on a conductive substrate. The charge generation layer is made of a phthalocyanine compound having an absorption peak in an infrared light region for a laser printer, or an azo compound having an absorption peak in a visible light region for a copying machine. It is formed by applying a coating solution dispersed in a binder resin binder such as a binder resin. On the other hand, the charge transport layer is hydrazone,
A low molecular compound such as a stilbene derivative or the like is used as a charge transport material, and a coating solution is formed by coating with a binder resin binder such as polycarbonate.

In actual image formation using the laminated photoreceptor, the Carlson method is applied. Specifically, charging the photoreceptor by corona discharge in a dark place, forming an electrostatic latent image such as a character or a picture on a document by exposing the charged photoreceptor surface, and toner of the formed electrostatic latent image , And the developed toner image is transferred and fixed to a support such as paper. After the charge removal, the removal of the residual toner, and the light charge removal after the transfer of the toner image, the toner image is reused. Such a stacked photoreceptor is advantageous in terms of characteristics because the charge generation section and the charge transport section are functionally separated, so that each can be optimally designed.

[0005]

As mentioned above, organic materials have many advantages, but none of them at the present time sufficiently satisfies all the electrophotographic properties required for photoreceptors. In the production process of the laminated photoreceptor, it is particularly important to disperse the organic pigment, which is a charge generating substance, in an organic solvent. If the organic pigment component increases, dispersibility and liquid stability deteriorate. In particular, the influence on the liquid stability is large, and the average particle size of the pigment in the dispersion liquid increases with time, thereby deteriorating the coatability and causing uneven coating. As a result, image unevenness due to poor appearance is caused. Further, the photoreceptor has the disadvantage that the charge retention rate is reduced and the quality stability is reduced. This is due to the formation of secondary aggregates by the pigment particles, and has conventionally been addressed by increasing the number of steps such as performing surface modification or redispersing the coating liquid to eliminate this drawback. However, it was not preferable because it increased the cost. In general, to improve dispersibility,
Although surfactants are effective, none of them have been obtained which function sufficiently to improve the dispersibility of the coating solution of the photoreceptor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to improve and stabilize the dispersibility of an organic pigment in a coating solution for a charge generating layer, thereby providing a highly sensitive and stable quality for electrophotography. An object of the present invention is to provide a method for manufacturing a photoconductor.

[0007]

If above object of the Means for Solving the Problems] is According to the present invention conductive charge generation layer on a substrate, the manufacturing method of the charge transport layer formed by providing an electrophotographic photoreceptor, sodium
This is achieved by dispersing a charge generating substance in an organic solvent using at least one selected from the group consisting of alkoxides and potassium alkoxides , and forming a charge generating layer using this coating solution.

In the above invention, the organic solvent is a ketone,
It is effective that at least one selected from the group consisting of ethers and alcohols, or that the charge generating substance is a bisazo pigment. In addition, sodium al
Small amount selected from the group of coxides and potassium alkoxides
At least one content ratio to the charge generating substance is 0.0
It may be in the range of 5% to 2% by weight. Natori
Specific examples of the alkoxide and the potassium alkoxide are shown in Chemical Formulas (I-1) to (I-19).

[0009]

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[0010]

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[0011]

[Action] Sodium alkoxide or potassium alcohol
By allowed to adding Kishido, it improves the dispersion stability in an organic solvent of the charge generating material. The dispersibility is best when the organic solvent is at least one selected from the group consisting of ketones, ethers and alcohols or when the charge generating substance is a bisazo pigment.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a negatively-charged laminated electrophotographic photosensitive member according to an embodiment of the present invention. The photoreceptor comprises a support 1, a charge generation layer 2, and a charge transport layer 3. The charge generation layer 2 and the charge transport layer 3 form a photosensitive layer 4.
In the figure, open circles indicate dispersants.

FIG. 2 is a cross-sectional view showing a positively charged lamination type electrophotographic photosensitive member according to an embodiment of the present invention. The photoreceptor comprises a support 1, a charge transport layer 3, a charge generation layer 2, and a surface coating layer 5. The charge generation layer 2 and the charge transport layer 3 comprise a photosensitive layer 4
Becomes In the figure, open circles indicate dispersants. As the conductive substrate 1 as a support, a conductive substrate alone such as an aluminum cylinder or an aluminum vapor-deposited film, an alumite-coated surface of the conductive substrate, or a surface modified with a resin film or the like is used. Used. In this embodiment, the conductive substrate is made of aluminum and has a thickness of 1 mm.
A cylindrical substrate having a length of 310 mm and an outer diameter of 60 mm was washed and dried. Materials for the polymer dispersion film used for surface modification include insulating polymers such as casein, polyvinyl alcohol, nylon, polyamide, melanin, and cellulose; conductive polymers such as polythiophene, polypyrrole, and polyaniline; Oxide powders and those containing low molecular compounds are used.

The charge generation layer 2 is composed of a charge generation substance and a resin binder. As the charge generating substance, a bisazo compound can be used. Examples of the binder for the charge generation layer include polycarbonate, polyester, polyamide, polyurethane, epoxy polyvinyl butyral, polyvinyl acetal, phenoxy resin, silicone resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, cellulose resin, and the like. And their halides and cyanoethyl compounds.

The charge transport layer 3 comprises a charge transport material and a resin binder. Examples of charge transport materials include hydrazone compounds, butadiene compounds, amine compounds,
A styryl compound and a distyryl compound can be used alone or in combination. Various polycarbonates, polystyrenes, polyphenylene ether acrylic resins and the like can be used as the resin binder for charge transport. Example 1 4 parts by weight of polyamide (trade name: T171, manufactured by Daicel-Hulls Co., Ltd.) and styrene-maleic acid resin (trade name: Suprapearl AP20, BASF Japan L)
td. 1 part by weight) in a mixed solvent of 200 parts by weight of methanol and 100 parts by weight of 1-butanol using a resin coating solution prepared and adjusted.
1 μm was formed by the Dip method to prepare a support.

10 parts by weight of a bisazo compound represented by the following chemical formula (II) as a charge-generating substance, 10 parts by weight of polyvinyl acetal (trade name: ESREC KS-1: Sekisui Chemical Co., Ltd.) as a binder resin, and methyl ethyl ketone 800
Parts by weight, and further added sodium methylate 0.1 as shown in the above formula (I-1) as an alkali metal-containing substance.
After adding 02 parts by weight (0.2% by weight), the mixture was kneaded with a mixer for 3 hours to prepare a coating liquid for a charge generation layer.

[0017]

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1000 parts by weight of a compound represented by the following chemical formula (III) as a charge transport material, 1000 parts by weight of a bisphenol A type-biphenyl copolymerized polycarbonate (trade name: BP-Pc: manufactured by Idemitsu Kosan) as a resin binder,
2,6-di-tert-butyl-4-as an antioxidant
50 parts by weight of methyl phenol is added to dichloromethane 7000
Dissolved in parts by weight, silicone oil K as a surface lubricant
P340 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added and mixed to prepare a coating solution for the charge transport layer.

Using the above coating solution, a charge generating layer of 0.3 μm and a charge transporting layer of 30 μm were sequentially formed on the above-mentioned support by a Dip method to prepare a photoreceptor.

[0020]

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Examples 2 to 9 Photoreceptors were prepared in the same manner as in Example 1 except that the composition of the alkali metal-containing substance in Example 1 was changed. The composition of the alkali metal-containing substance used is shown in Table 1 together with the characteristics of the evaluated photoreceptor. Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that no alkali metal-containing substance was added to the coating solution for the charge generation layer. Example 10 A photoconductor was prepared by the same way as that of Example 1 except that the charge generating material of Example 1 was changed to a compound represented by the following chemical formula (IV).

[0022]

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Example 11 A photoconductor was prepared by the same way as that of Example 1 except that the charge generating material of Example 1 was changed to a compound represented by the following chemical formula (V).

[0024]

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Comparative Example 2 A photoconductor was prepared in the same manner as in Example 10, except that no alkali metal-containing substance was added to the coating solution for the charge generation layer. Comparative Example 3 A photoconductor was prepared by the same way as that of Example 11 except that the alkali metal-containing substance in the coating solution for the charge generation layer was not mixed.

Each of the coating liquids for forming the respective charge generating layers was left for one week, and photoreceptors were prepared in the same manner as in the examples and comparative examples. The electrophotographic properties of the thus obtained laminated organic photoreceptor were measured by attaching it to a test machine having a process simulating an electrophotographic copying machine.
The measurement conditions are shown below.

The surface of the photosensitive member is -800 V by corona discharge.
After 5 seconds, the charge retention in the dark after 5 seconds is expressed as V
k5 (%). It is charged to -800 V and has an illuminance of 2
Irradiation of (lx) white light was performed, and the time required for the surface potential to reach -400 V was determined and defined as a half-attenuated exposure amount E1 _{/ 2} . The results are shown in Table 1.

[0028]

[Table 1]

(The addition amount of the alkali metal-containing substance is represented by weight% with respect to the charge generation substance.) As is apparent from the above results, the alkali metal-containing substances were obtained from Examples 1 to 9 and Comparative Example 1. When the substance was not added, the Vk5 decreased, but when the alkali metal-containing substance was added in the range of 0.05% by weight to 2% by weight, the average particle diameter was obtained even when the coating solution was left for one week. Did not change. Also, there was no change in the half-life exposure amount in the prepared photoreceptor, and no decrease in Vk5 was observed. On the other hand, when the added amount of the alkali metal-containing substance was small, the average particle size was significantly increased, and when it was large, Vk5 was decreased. Also, when the charge generating substance was changed, no deterioration in electrophotographic properties due to the alkali metal-containing substance was confirmed. From the above, it can be seen that when the alkali metal-containing substance was added, the storage stability of the coating solution was good. Example 12 1000 parts by weight of a compound represented by the following chemical formula (VI) as a charge transporting substance, and bisphenol A type-biphenyl copolymerized polycarbonate (trade name BP) as a resin binder
-Pc: Idemitsu Kosan Co., Ltd. (1000 parts by weight), 2,6-di-tert-butyl-4-methylphenol (50 parts by weight as an antioxidant) dissolved in 7000 parts by weight of dichloromethane, and silicone oil KP340 (Shin-Etsu) as a surface lubricant (Manufactured by Kagaku) was added and mixed to prepare a coating solution for the charge transport layer. 10 parts by weight of a bisazo compound represented by the following chemical formula (VII) as a charge generating substance, and 10 parts by weight of polyvinyl acetal (trade name ESREC KS-1: Sekisui Chemical Co., Ltd.) as a binder resin are mixed with 800 parts by weight of methyl ethyl ketone. Then, 0.02 parts by weight (0.2% by weight) of sodium methylate was added and kneaded with a mixer for 3 hours to prepare a coating liquid for a charge generation layer.

Using the above coating solution, a charge transporting layer of 15 μm and a charge generating layer of 0.5 μm were sequentially formed on the above-mentioned support by a Dip method to prepare a photoreceptor.

[0031]

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Examples 13 to 20 Photoconductors were prepared in the same manner as in Example 12, except that the composition of the alkali metal-containing substance in Example 12 was changed. The composition of the metal-containing substance used is shown in Table 2 together with the characteristics of the photoreceptor evaluated. Comparative Example 4 A photoconductor was prepared by the same way as that of Example 12 except that no alkali metal-containing substance in the charge generating layer coating solution was added.

Each of the coating liquids for forming the respective charge generating layers was allowed to stand for one week, and photoreceptors were prepared in the same manner as in the examples and comparative examples. The electrophotographic properties of the thus obtained laminated organic photoreceptor were measured by attaching it to a test machine having a process simulating an electrophotographic copying machine.
The measurement conditions are shown below.

+800 V on the surface of the photoreceptor by corona discharge
After the positive charge, the charge retention rate in the dark after 5 seconds is V
k5 (%). In addition, it is charged to +800 V and illuminance 2
(Lx) White light irradiation was performed to determine the time required for the surface potential to reach +400 V, which was defined as a half-attenuated exposure amount E1 _{/ 2} . Table 2 shows the results.

[0035]

[Table 2]

(The addition amount of the alkali metal-containing substance is represented by weight% with respect to the charge generating substance.) As is apparent from the above results, the alkali metal-containing substance was obtained from Examples 12 to 20 and Comparative Example 4. Vk when not adding
5 was observed, but the content of the alkali metal-containing material was 0.0%.
When it was added in the range of 5% by weight to 2% by weight, no change was observed in the average particle size even after the coating solution was left for one week.
Also, there is no change in the half-life exposure amount in the created photoconductor,
No decrease in Vk5 was observed. On the other hand, when the added amount of the alkali metal-containing substance was small, the average particle size was significantly increased, and when it was large, Vk5 was decreased. From the above, it can be seen that when the alkali metal-containing substance was added, the storage stability of the coating solution was good.

[0037]

According to the present invention, sodium alkoxy
And the charge generation layer is formed using a coating solution in which the charge generation material is dispersed in an organic solvent using at least one selected from the group of potassium alkoxides. As a result, the coatability is improved, and the appearance of the photoreceptor is improved, so that a photoreceptor excellent in electrophotographic characteristics in either positively or negatively charged state can be stably obtained.

When the organic solvent is at least one selected from the group consisting of ketones, ethers and alcohols, or when the charge generating substance is a bisazo pigment, the dispersibility is best, and the charge is positively or negatively charged. In either case, a photosensitive member having excellent electrophotographic characteristics can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a negatively charged laminated electrophotographic photosensitive member according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a positively charged lamination type electrophotographic photoconductor according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive substrate 2 charge generation layer 3 charge transport layer 4 photosensitive layer 5 surface coating layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-279342 (JP, A) JP-A-4-118662 (JP, A) JP-A-4-162041 (JP, A) JP-A-2- 146550 (JP, A) JP-A-5-303213 (JP, A) JP-A-5-333570 (JP, A) JP-A-5-297615 (JP, A) JP-A-4-122946 (JP, A) JP-A-6-236054 (JP, A) JP-A-7-152168 (JP, A) JP-A-7-319185 (JP, A) JP-A 8-29992 (JP, A) JP-B-47-47250 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 5/00

Claims (4)

(57) [Claims] 1. A conductive charge generation layer on a substrate, the manufacturing method of the charge transport layer formed by providing an electrophotographic photoreceptor, diisocyanato
Electrophotography wherein a charge generation material is dispersed in an organic solvent using at least one selected from the group consisting of a lithium alkoxide and a potassium alkoxide , and a charge generation layer is formed by a Dip method using this coating solution. Manufacturing method of photoreceptor. 2. The method according to claim 1, wherein the organic solvent is at least one selected from the group consisting of ketones, ethers and alcohols. . 3. The method according to claim 1, wherein the charge generating substance is a bisazo pigment. 4. The method according to claim 1, wherein
In the production method, sodium alkoxide, potassium
At least one charge selected from the group of alkoxides
The content ratio to the generated substance is 0.05% by weight to 2%
% Of the electrophotographic photoreceptor,
Production method.