JPH0456866A - Electrophotographic photosensitive body - Google Patents

Abstract

PURPOSE:contrive the improvements in the ozone oxidation resistance and a plate wearing property by incorporating a specified amine derivative in the remotest layer from a conductive supporting body. CONSTITUTION:The remotest layer from the conductive carrier 4 is incorporated with an amine derivative represented with formula I. In formula I, R represents a methyl group or an isobutyl group. In the photosensitive layer 3, the order of the laminated layers can be from either the charge generating layer 1 or the charge transfer layer 2 or it may be a single layer type in which a charge generation and a transfer are conducted, but when a surface protective layer 5 is formed, a composition incorporating a hardened type resin and an amine derivative represented with formula I as major components, is applied and formed. Thus the resistance to oxygen and the plate wearing property are improved.

Description

[Detailed Description of the Invention] [Summary] An electrophotographic photoreceptor that has improved ozone oxidation resistance and has excellent printing durability, which is widely used in copiers, printers, etc. that apply electrophotography. In an electrophotographic photoreceptor having a photoconductive photosensitive layer on a conductive support or a surface protective layer on the photoconductive photosensitive layer, the layer layer farthest from the conductive support is It is configured to contain an amine derivative represented by the following structural formula (I).

@-NH-@-NH-CH(CH3)-R(I) (In the formula, R represents a methyl group or an isobutyl group.) [Industrial Application Field] The present invention is directed to copying using an electrophotographic method. It relates to electrophotographic photoreceptors that are widely used in machines, printers, etc.

As an example of electrophotography, a common method is to obtain a printed matter by repeating the steps of charging, exposing, developing, transferring, and fixing.

The charging process applies a uniform positive or negative electrostatic charge to the surface of the photoconductive photoreceptor. In the subsequent exposure process, an electrostatic latent image corresponding to the image information is formed on the photoreceptor by irradiating it with laser light or the like to erase the surface charge on a specific portion. Next, this latent image is electrostatically developed with powder ink called toner, thereby forming a visible image of the toner on the photoreceptor. Finally, this toner image is electrostatically transferred onto recording paper and fused using heat, light, pressure, etc. to obtain a printed matter.

The surface of the photoreceptor is abraded due to development with toner, friction with paper, friction during cleaning, and the like.

Therefore, it is necessary to develop a photoreceptor with excellent wear resistance and printing durability.

[Prior Art] Inorganic photoreceptors typified by selenium-based photoreceptors have been widely used as photoreceptors having photoconductivity.

This inorganic photoreceptor has high sensitivity and is resistant to mechanical wear.
Although it has the advantage of being suitable for high-speed, large-scale machines, it is expensive due to the fact that it must be manufactured using a vacuum evaporation method and must be recovered because it is harmful to the human body, and it is not suitable for small, maintenance-free machines. The problem was that it was difficult to apply to low-cost machines.

Organic photoreceptors were developed as an alternative to inorganic photoreceptors. This material can be manufactured by a coating method, making it easy to reduce costs through mass production. Compared to inorganic photoreceptors that use inorganic substances such as selenium, this material has a wider range of material selection, allowing the selection of non-hazardous compounds. It has the advantage of being maintenance-free.

In particular, as shown in FIG. 2, a functionally separated laminated photoreceptor in which a charge generation layer 1 and a charge transport layer 2 are laminated has attracted attention. Here, the charge generation layer 1 has a function of absorbing incident light and generating electron-hole pairs (carrier pairs), and the charge transport layer 2 retains a charge on its surface, and the charge generation layer 1 has a function of generating electron-hole pairs (carrier pairs). It has the function of transporting one of the generated carriers to the surface of the photoreceptor to form an electrostatic latent image.

The charge generation layer 1 is formed by forming a charge generation substance that absorbs light and generates carrier pairs into a vapor deposited film or by dispersing it in a binder resin. Azo pigments, phthalocyanine, and the like are known as charge-generating substances, and polyester, polyvinyl butyral, and the like are used as binder resins.

The charge transport layer 2 is formed by dissolving a charge transport material having a carrier transport function in a binder resin. As charge transport substances, electron transport charge transport substances such as trinitrofluorenone and chloranil, which have the property of transporting electrons,
There are hole-transporting charge-transporting substances such as hydrazone and pyrazoline that have the property of transporting holes, and polycarbonate, styrene-acrylic, and the like are used as the binder resin.

By separating the functions of the photoreceptor into two layers in this way, it is possible to select the optimal compound for each function almost independently, improving various properties such as sensitivity, spectral characteristics, and mechanical abrasion resistance. can be done.

However, such organic photoreceptors still have lower abrasion resistance than inorganic photoreceptors such as selenium, making it difficult to apply them to high-speed, large-scale machines that require high printing durability. In other words, the surface of the photoreceptor wears out due to toner development, friction with paper, and friction during cleaning, and many scratches occur on the surface, so its applicability is limited to low-speed, small machines. is the current situation. Normally, in the case of a blade cleaning process, after printing about 10,000 sheets, the surface of the photoreceptor wears out by several micrometers, and the charging ability decreases.
Many scratches occur on the surface. These deteriorate printing quality, making it necessary to replace the photoreceptor.

In order to solve these problems, attempts have been made to increase the hardness of the photoreceptor surface and improve its wear resistance. Specifically, the surface hardness of the photoreceptor is increased by providing a highly hard protective layer on the surface of the photoreceptor or using a highly hard resin as the binder resin of the charge transport layer 2. As these highly hard resins, curable resins such as silicone-based, melamine-based, isocyanate-based, and acrylate-based resins are usually used.

In FIG. 2, 3 is a photosensitive layer, and the photosensitive layer 3 is composed of a charge generation layer 1 and a charge transport layer.

[Problem to be solved by the invention] However, in such a photoreceptor, ozone is generated due to corona discharge during the charging process, so the surface of the photoreceptor is exposed to high concentration of ozone. . Since ozone has a strong oxidizing effect, highly reactive substances are easily oxidized and even decomposed. The above-mentioned curable resin has relatively highly reactive functional groups such as double bonds and hydroxyl groups, so when these are used in the surface layer of the photoreceptor, they are easily damaged by ozone generated during charging. It is oxidized and cannot maintain its initial properties.

That is, various problems occur, such as the curable resin being decomposed by oxidation, making it impossible to obtain the desired hardness, or oxidation producing hygroscopic substances on the surface of the photoreceptor, which significantly impairs environmental stability.

In particular, in the latter case, the conductivity changes significantly due to moisture absorption, so when dry, the conductivity of the surface layer decreases and charges accumulate, resulting in blurred images. The increased conductivity causes charge to move toward the surface, resulting in blurring of the image.

Furthermore, even when resins other than curable resins are used, similar problems may occur if exposed to high concentration ozone for a long period of time.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an electrophotographic photoreceptor having improved ozone oxidation resistance and excellent printing durability.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an electrophotographic photosensitive layer having a photoconductive photosensitive layer on a conductive support, or a surface protective layer on the photoconductive photosensitive layer. In the body, the layer farthest from the conductive support is an amine derivative represented by the following structural formula (I), an amine derivative represented by the following structural formula (n), or an amine derivative represented by the following structural formula (III). It contains a dithiocarbamic acid derivative.

@-NH-@-NH-CH(CH3) -R(I) (In the formula, R represents a methyl group or an isobutyl group.) )NH+NH-◎ (n) (III) (In the formula, R represents ethyl or butyl group.) Below,
The present invention will be described in further detail with reference to FIG. 1 as necessary.

In FIG. 1, 1 is a charge generation layer, 2 is a charge transport layer, and 3 is a charge generation layer.
1 is a photoconductive photosensitive layer composed of a charge generation layer 1 and a charge transport layer 2, 4 is a conductive support, and 5 is a surface protective layer.

The conductive support 4 may be anything that can ground the photoreceptor, such as various metal cylinders, cylinders made of conductive resin or paper, insulating cylinders with metal vapor-deposited or laminated on the surface, or insulating cylinders. A cylinder having a conductive organic thin film applied thereto, a film having the same structure as above, etc. can be used.

The charge generating substance constituting the charge generating layer 1 or contained in the charge generating layer includes azo type, phthalocyanine type,
Various dyes and pigments such as indigo, perylene, squarylium, quinone, and pyrylium can be used, but particularly good sensitivity can be obtained by using phthalocyanine pigments. As the phthalocyanine, various metal phthalocyanines such as metal-free phthalocyanine, copper phthalocyanine, aluminum chloride phthalocyanine, titanyl phthalocyanine, vanadyl phthalocyanine, and indium phthalocyanine can be used.

The charge generating layer 1- is formed by depositing these charge generating substances on the support 4, or by coating and drying a mixture dispersed in a solvent together with a binder resin. As the binder resin, various resins such as polyester, polyvinyl alcohol, polyvinyl acecool, polyamide, epoxy, and silicone, or various organic compounds with film-forming properties such as casein can be used, and they have good adhesion to the substrate and charge-generating substances. Selection should be made taking into account the dispersibility of The solvent is selected according to the charge generating substance and binder resin used, but examples include tetrahydrofuran, dioxane, methanol, ethanol, hexane, ether, dichloromethane, dichloroethane, benzene, toluene, chlorobenzene, xylene, methyl cellosolve, ethyl cellosolve, ethyl acetate, etc. Various organic solvents can be used alone or in combination. Methods for coating the support 4 include dip coating, spray coating, wire barcode coating, and doctor blade coating. Film thickness is 0.01~3μ
The thickness is preferably about 1 μm or less.

The charge transport layer 2 is formed by dissolving a charge transport substance in a binder resin. Any known charge transport substance may be used, and electron transport substances such as trinitrofluorenone, chloranil, and promanyl, and hole transport charge transport substances such as hydrazone derivatives, pyrazoline derivatives, and triphenylamine derivatives are used. be able to. Further, as the charge transport layer 2, a polymer such as polyvinylcarbazole, which has film-forming properties and charge transport ability by itself, can also be used.

As the binder resin for the charge transport layer 2, polycarbonate, polyester, polystyrene, polyacrylonitrile, acrylic-styrene, polysulfone, polyvinyl acetal, polyamide, etc. are used, and representative examples include silicone-based, melamine-based, isocyanate-based, and acrylate-based. A curable resin may be added or used alone, and filler components such as colloidal silica and various known additives may also be added. The solvent for coating is appropriately selected as in the case of coating the charge generation layer 1. As for the coating method, the same method as in the case of the charge generation layer 1 can be used. The film thickness is preferably 5 to 50 μm, more preferably 10 to 30 μm. When a curable resin is used as the binder, a polymerization initiator is added if necessary, and the resin is cured using heat, light, electron beams, radiation, or the like.

Further, the photosensitive layer 3 may have the charge generation layer 1 and the charge transport layer 2 in the reverse order, or may be of a single layer type in which charge generation and transport occur in a single layer.

When forming the surface protective layer 5, a curable resin and an amine derivative represented by the above structural formula (I), or a combination of a curable resin and an amine derivative represented by the above structural formula (I) are used.
n) or the above structural formula (II
It is formed by applying a composition containing the dithiocarbamic acid derivative represented by I) as a main component.

In this case, the content of the amine derivative or dithiocarbamic acid derivative is 0.01% to 10% based on the total weight.
It is more preferably about 1 to 5%. Any known curable resin may be used, and silicone-based, melamine-based, isocyanate-based, acrylate-based, etc. are used, and if necessary, filler components such as polymerization initiators and colloidal silica, and various known additives may be added. May be added.

Further, the solvent for coating is appropriately selected as in the case of coating the charge generation layer 1. As for the coating method, the same method as in the case of the charge generation layer 1 can be used. The film thickness is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm.
It is μm. As the curing method, heat, light, electron beam, radiation, etc. can be used as in the case of the charge transport layer 2.

In addition, when the surface protective layer 5 is not formed, the layer farthest from the conductive support 4 is an amine derivative represented by the structural formula (I), or an amine derivative represented by the structural formula (n), Alternatively, it contains a dithiocarbamic acid derivative represented by the above structural formula (III). For example, when the conductive support 4, the charge generation layer 1, and the charge transport layer 2 are laminated in this order, the conductive support 4,
When the charge transport layer 2 and charge generation layer 1 are laminated in this order, it is contained in the charge generation layer 1, and when the photosensitive layer 3 is a single layer type, it is contained in the single layer.

Further, the content of the amine derivative or dithiocarbamic acid derivative is about 0.01% to 10%, more preferably about 1 to 5%, based on the total weight.

Between the conductive support 4 and the photosensitive layer 3, there are various treatments such as improving adhesion, flattening the surface of the support, covering defects on the surface of the support, controlling hot carrier injection, and improving charge acceptance and charge retention. A subbing layer may be provided for this purpose. The constituent material of the undercoat layer may be a film-forming material such as various binder resins or casein used in the charge generation layer 1 or the charge transport layer 2, or a material containing a conductive substance therein. A material whose resistance value is adjusted to 1014 Ω·cm or less can be used. The electrically conductive material used to adjust the resistance value of the undercoat layer may be any electrically conductive material, such as various metal powders, electrically conductive metal oxide powders, and carbon.

[Function] In this way, the structural formula (■) or the structural formula (
n) or the above structural formula (II
Since the dithiocarbamic acid derivative represented by I) is contained, ozone oxidation resistance can be improved.

As a result, an electrophotographic photoreceptor with excellent printing durability can be obtained.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example] Example 1 First, a photoreceptor is manufactured as follows.

That is, 1 part by weight of titanyl phthalocyanine, 1 part by weight of polyester, and 38 parts by weight of tetrahydrofuran were dispersed and mixed for 24 hours using a hard glass pole and a hard glass pot, and the mixture was dip coated onto an aluminum cylinder and heated at 100°C.
This was dried for 1 hour to form a charge generation layer having a thickness of 0.3 μm.

Next, 2 parts by weight of a hydrazone derivative represented by the following structural formula (IV) and 1 part by weight of polycarbonate were dissolved in 9 parts by weight of tetrahydrofuran, applied by dip coating onto the charge generation layer, and dried at 70°C for 2 hours. A charge transport layer having a thickness of 20 μm was formed.

Next, 1 part by weight of an acrylate derivative represented by the following structural formula (V), 0.01 part by weight of benzoyl peroxide, and 0.01 part by weight of an amine derivative represented by the following structural formula (VI) were added to 5 parts by weight of ethanol. and applied by dip coating onto the charge transport layer of a photoreceptor manufactured according to the photoreceptor manufacturing example, and
C. for 2 hours to form a surface protective layer with a thickness of 1 μm. In this way, the photoreceptor of Example 1 was obtained.

Example 2 1 part by weight of an acrylate derivative represented by the following structural formula (V), 0.01 part by weight of benzoyl peroxide, and 0.01 part by weight of an amine derivative represented by the above structural formula (n) were added to 5 parts by weight of ethanol. The solution was applied by dip coating onto the charge transport layer of a photoreceptor manufactured according to the photoreceptor manufacturing example described above, and cured at 70° C. for 2 hours to form a surface protective layer with a thickness of 1 μm. In this way, a photoreceptor of Example 2 was obtained.

Example 3 1 part by weight of an acrylate derivative represented by the following structural formula (V), 0.01 part by weight of benzoyl peroxide and the structural formula (■
0.01 part by weight of a dithiocarbamic acid derivative represented by ) is dissolved in 5 parts by weight of ethanol and applied by dip coating onto the charge transport layer of a photoreceptor manufactured according to the above production example of a photoreceptor,
It was cured at 70° C. for 2 hours to form a surface protective layer with a thickness of 1 μm. In this way, a photoreceptor of Example 3 was obtained.

Comparative Example A charge transport layer of a photoreceptor was prepared by dissolving 1 part by weight of an acrylate derivative represented by the following structural formula (V) and 0.01 part by weight of benzoyl peroxide in 5 parts by weight of ethanol, and manufactured according to the above production example of a photoreceptor. It was dip-coated on top and cured at 70° C. for 2 hours to form a surface protective layer with a thickness of 1 μm. In this way, a photoreceptor of a comparative example was obtained.

(rV) (V) (In the formula, X, ~X6 are Represents CH2=C(CH3)COOCH2CH2O.

) (Vl) (■) In order to investigate the durability (ozone oxidation resistance) of the four types of photoreceptors mentioned above, these photoreceptors were installed in a printer, a 50,000-sheet printing test was conducted, and the potential characteristics were measured. went. These results are shown in Table 1.

In the comparative photoreceptor containing no amine derivative or dithiocarbamic acid derivative, the image became blurred during drying after about 10,000 sheets were printed, and the image also became blurred in a high-humidity environment. Furthermore, as can be seen from Table 1, the potential characteristics also varied significantly compared to the initial stage. From the above,
The durability of this photoreceptor was determined to be approximately 10,000 sheets.

On the other hand, Example 1. 2. With the photoreceptor containing the amine derivative or dithiocarbamic acid derivative of No. 3, no deterioration in image quality was observed even after approximately 50,000 sheets were printed. Further, as shown in Table 1, the potential characteristics were also stable, and from the above, the printing durability of these photoreceptors was determined to be 50,000 sheets or more.

Table 1 ■. : Potential of non-exposed area (V) vL : Electron of exposed area (V) Image quality ○: No blurring or blurring ×: Blurring or blurring [Effects of the Invention] As explained above, according to the present invention, the surface The protective layer or the layer farthest from the conductive support has the above structural formula (
I) or the above structural formula (II)
) or the above structural formula (III
By containing the dithiocarbamic acid derivative represented by ), ozone oxidation resistance is improved, and an electrophotographic photoreceptor with excellent durability can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is a configuration diagram of a conventional example. In the figure, 1... Charge generation layer, 2...charge transport layer, 3... Photosensitive layer, 4...Support, 5...Surface protective layer.

Claims (3)

[Claims] (1) In an electrophotographic photoreceptor having a photoconductive photosensitive layer on a conductive support or a surface protective layer on the photoconductive photosensitive layer, the layer farthest from the conductive support has the following structural formula (
An electrophotographic photoreceptor comprising an amine derivative represented by I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R represents a methyl group or an isobutyl group.) (2) In an electrophotographic photoreceptor having a photoconductive photosensitive layer on a conductive support or a surface protective layer on the photoconductive photosensitive layer, the layer farthest from the conductive support has the following structural formula (
An electrophotographic photoreceptor comprising an amine derivative represented by II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II) (3) In an electrophotographic photoreceptor having a photoconductive photosensitive layer on a conductive support or a surface protective layer on the photoconductive photosensitive layer, the layer farthest from the conductive support has the following structural formula (
An electrophotographic photoreceptor comprising a dithiocarbamic acid derivative represented by III). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (III) (In the formula, R represents an ethyl group or a butyl group.)