JPH04289867A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body excellent in sensitivity and print resistance, in the case of the electrophotographic sensitive body wide used in a printing machine, printer, etc., of applying an electrophotographic system. CONSTITUTION:In the case of an electrophtographic sensitive body having a sensitized layer on a conductive supporter, the sensitized layer is constituted so as to contain a polysilane compound having a fluoroalkyl group.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor that is widely used in copying machines, printers, etc. that utilize electrophotography. A common electrophotographic method is to obtain 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 a 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 using a powder ink called toner, thereby forming a visible image using 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.

0003

[Prior Art] As the above-mentioned photoconductor having photoconductivity,
Inorganic photoreceptors typified by selenium-based photoreceptors were widely used. This inorganic photoreceptor has high sensitivity and is resistant to mechanical wear.
Although it has the advantage of being suitable for high-speed, large-sized copiers and printers, it is costly and maintenance-free because it must be manufactured using a vacuum deposition method and must be recovered as it is harmful to the human body. The problem was that it was difficult to apply it to small, low-cost machines.

Organic photoreceptors have been developed as an alternative to inorganic photoreceptors. This material can be manufactured by a coating method, which makes it easy to reduce costs through mass production, and because it has a wider range of materials to choose from than inorganic photoreceptors that use inorganic materials such as selenium, non-hazardous compounds can be selected. It has the advantage of being maintenance-free.

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

Factors governing the sensitivity characteristics of such a laminated photoreceptor include (1) carrier generation efficiency in the charge generation layer 1 and (2) carrier transfer from the charge generation layer 1 to the charge transport layer 2. Possible factors include injection efficiency and (3) carrier mobility in the charge transport layer 2. In addition, in the figure, 3 is a photosensitive layer, and 4 is a conductive support. 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 to form a thin film.

Azo pigments, phthalocyanines, and the like are known as charge-generating substances, and polyesters, polyvinyl butyral, and the like are used as binder resins. The charge transport layer 2 is formed by dissolving a charge transport material having carrier transport ability into a binder resin. Charge transport materials include electron transport charge transport materials such as trinitrofluorenone and chloranil, which have the property of transporting electrons, and hole transport charge transport materials such as hydrazone and pyrazoline, which have the property of transporting holes. Polycarbonate, styrene-acrylic, etc. are used as the binder resin.

[0008] Still, it has many problems compared to conventional inorganic photoreceptors such as selenium, so it is difficult to apply it to high-speed, large-sized copying machines and printers. For example, the carrier mobility of the charge transport materials used so far is low and it takes time to form a latent image, so the current application range of organic photoreceptors is limited to low-speed, small-sized machines.

In order to solve this problem, organic polysilane compounds are being developed. An organic polysilane compound has a molecular structure intermediate between an inorganic compound and an organic compound, and is therefore a charge transport material having an extremely high mobility of 10 −4 (cm 2 /Vs). That is, by employing an organic polysilane compound, sensitivity comparable to that of an inorganic photoreceptor can be achieved.

0010

[Problems to be Solved by the Invention] However, such conventional organic photoreceptors still have lower wear resistance than conventional inorganic photoreceptors such as selenium, and high printing durability is required. Application to high-speed, large-scale aircraft was still difficult. That is, many scratches are generated on the surface due to development with toner, friction with paper, etc., and as a result, the print quality is significantly degraded. In addition, the surface of the photoreceptor is worn away due to friction during cleaning, and normally in the case of a blade cleaning process, the surface of the photoreceptor is worn several micrometers after printing about 10,000 sheets, reducing the charging ability. , printing may become foggy or faded. Therefore,
If more printing is to be performed, the photoreceptor must be replaced.

The present invention has been made in view of these conventional problems, and an object of the present invention is to provide an electrophotographic photoreceptor having excellent sensitivity and printing durability.

0012

Means for Solving the Problems In order to achieve the above object, the present invention provides an electrophotographic photoreceptor having a photosensitive layer on a conductive support, in which the photosensitive layer comprises a polysilane compound having a fluorinated alkyl group. It contains.

The present invention will be explained in more detail below. That is, the polysilane compound has lower frictional properties than conventionally studied compounds without fluorinated alkyl groups,
An electrophotographic photoreceptor with excellent wear resistance can be obtained. This is considered to be due to the low friction and non-adhesive properties of the fluorinated alkyl group. Here, the fluorinated alkyl group is more effectively a trifluoroethyl group or perfluorooctyl group, but any organic group having a carbon-fluorine bond may be used.

The conductive support 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 on the surface, or insulating cylinders. A cylinder with a metal film or a conductive organic film applied thereto, a film having the same structure as above, etc. can be used. Various dyes and pigments such as azo-based, phthalocyanine-based, indigo-based, perylene-based, squarylium-based, and quinone-based dyes and pigments can be used as charge-generating substances constituting or contained in the charge-generating layer, but phthalocyanine-based Good sensitivity can be obtained by using pigments based on pigments.

As the phthalocyanine, various metal phthalocyanines can be used, such as metal-free phthalocyanine, copper phthalocyanine, aluminum chloride phthalocyanine, titanyl phthalocyanine, vanadyl phthalocyanine, and indium phthalocyanine. The charge generating layer is formed by vapor depositing these charge generating substances on the support, 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 acetal, polyamide, epoxy, and silicone, or various organic compounds with film-forming properties such as casein can be used. Select by considering dispersibility etc.

The solvent is selected depending on the charge generating substance and binder resin used, and examples include tetrahydrofuran, dioxane, methanol, ethanol, hexane, ether, dichloromethane, dichloroethane, benzene, toluene,
Various organic solvents such as chlorobenzene, xylene, methyl cellosolve, ethyl cellosolve, and ethyl acetate can be used alone or in combination.

[0017] Methods for coating the support include dip coating, spray coating, wire bar coating, and doctor blade coating. The film thickness is approximately 0.01 to 3 μm, more preferably 1 μm or less. The charge transport layer is formed by applying a composition containing a polysilane compound having a fluorinated alkyl group as a main component. The polysilane compound can be prepared by a known method (JP Wesso
n, T. C. Williams, J. Polym. Sc
i. Polym, Chem. , Ed. 18,959 (1
980)), for example, according to the following synthetic route.

[0018]

[Case 2]

(In the formula, R1 to R2 each represent an organic group such as an alkyl group or an aryl group, which may be the same or different, and at least one of them represents a fluorinated alkyl group such as a trifluoroethyl group or a perfluorohexyl group. represents an organic group having a group. Also, X represents a halogen.)
Other components of the composition include resins such as polycarbonate, polyester, polystyrene, polyacrylonitrile, polyacryl-styrene, polysulfone, polyvinyl acetal, polyamide, epoxy, and colloidal silica for the purpose of improving mechanical strength. Filler components and various known additives may also be added.

[0020] Also, the solvent is appropriately selected as in the case of coating the charge generation layer. The coating method can be the same as that for the charge generation layer. The film thickness is preferably 5-5
It is 0 μm, more preferably 10 to 30 μm. Further, in the photosensitive layer, the charge generation layer and the charge transport layer may be stacked in the opposite order, and the photosensitive layer may be a single layer type in which charge generation and transport are performed in a single layer.

Between the conductive support and the photosensitive layer, improvements such as improving adhesion, flattening the surface of the support, covering defects on the surface of the support, controlling the injection of hot carriers, and improving charge acceptance and charge retention, etc. A subbing layer may be provided for this purpose. The constituent material of the undercoat layer may be a film-forming material alone such as various binder resins or casein used in the charge generation layer or charge transport layer, or a conductive material may be added therein to increase the resistance value. It is possible to use a material whose resistance is adjusted to 1014 Ω·cm or less.

The conductive material used to adjust the resistance value of the undercoat layer may be any material having conductivity, such as various metal powders, conductive metal oxide powders, and carbon.

[0023]

[Operation] In the present invention, since the abrasion resistance of the surface is improved, an electrophotographic photoreceptor having excellent sensitivity and printing durability can be obtained.

[0024]

EXAMPLES The present invention will now be explained in more detail with reference to Examples, but the present invention is not limited thereto. Synthesis Example 1 After adding 3 parts by weight of trifluoroethylphenyldichlorosilane and 1 part by weight of metallic sodium to 100 parts by weight of toluene, the mixture was heated and stirred at 80° C. for 10 hours. After the reaction product was poured into ethanol and the precipitate was filtered, washing and reprecipitation were repeated to obtain the desired polysilane compound (1). The structural formula is shown in Table 1. Synthesis Examples 2 to 5 Synthesis was carried out in the same manner as in Synthesis Example 1, except that the raw material compounds shown in Table 1 were used instead of trifluoroethylphenyldichlorosilane, and the desired polysilane compound ( 2) to (5) were obtained. The structural formula is shown in Table 1. Example 1 1 part by weight of titanium oxide 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 ball and a hard glass pot, and the mixture was dip coated onto an aluminum cylinder and heated at 100°C for 1 hour. It was dried to form a charge generation layer with a thickness of about 0.3 μm.

Next, polysilane compound (1) 1 shown in Table 1
Parts by weight were dissolved in 9 parts by weight of chloroform, applied by dip coating onto the charge generation layer, and cured by heating at 80° C. for 2 hours to form a charge transport layer with a thickness of about 20 μm. In this way, the photoreceptor of Example 1 was obtained. Examples 2 to 4 Photoreceptors of Examples 2 to 4 were obtained in the same manner as in Example 1, except that compounds (2) to (4) in Table 1 were used instead of compound (1) as the polysilane compound. Ta. Comparative Example 1 A photoreceptor of Comparative Example 1 was obtained in the same manner as in Example 1 except that Compound (5) in Table 1 was used instead of Compound (1) as the polysilane compound. Comparative Example 2 1 part by weight of titanium oxide phlotocyanin, 1 part by weight of polyester, and 38 parts by weight of tetrahydrofuran were dispersed and mixed for 24 hours using a hard glass ball and a hard glass pot, and the mixture was dip-coated onto an aluminum cylinder and heated to 100°C. The mixture was dried for a period of time to form a charge generation layer with a thickness of about 0.3 μm.

Next, 1 part by weight of a hydrazone derivative represented by the following structural formula (2) and 1 part by weight of polycarbonate were dissolved in 9 parts by weight of tetrahydrofuran, and the solution was dip-coated onto the charge generation layer, and the solution was coated at 70° C. for 2 hours. Dry to a film thickness of approximately 20μ
A charge transport layer of m was formed. In this way, a photoreceptor of Comparative Example 2 was obtained.

[0027]

[Chemical formula 3]

In order to investigate the printing durability of the six types of photoreceptors mentioned above, these photoreceptors were attached to a blade cleaning type printer, a printing test of 50,000 sheets was conducted, and the potential characteristics were measured. These results are shown in Table 2. In the photoreceptors of Comparative Examples 1 and 2, many scratches were generated on the surface of the photoreceptor after printing about 10,000 sheets, and abrasion of the surface layer was also observed. In addition, streak-like patterns appeared in the printing due to scratches on the photoreceptor, and stains on the blank paper areas began to appear.

Furthermore, as can be seen from Table 2, the potential characteristics also varied greatly compared to the initial stage. From the above, the printing durability of this photoreceptor was determined to be approximately 10,000 sheets. In the photoreceptors of Examples 1 to 4, no scratches were observed on the surface of the photoreceptor even after 50,000 sheets were printed, and the printing maintained good print quality. Furthermore, as can be seen from Table 2, the potential characteristics were also relatively stable. From the above, the printing durability of these photoreceptors was determined to be 50,000 sheets or more.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Effects of the Invention] As described above, by including a polysilane compound having a fluorinated alkyl group in the photosensitive layer,
It is possible to obtain an electrophotographic photoreceptor with improved surface abrasion resistance and excellent sensitivity and printing durability.

[Brief explanation of the drawing]

[Figure 1] Configuration diagram of a conventional laminated photoreceptor

[Explanation of symbols]

1: Charge generation layer 2: Charge transport layer 3: Photosensitive layer 4: Conductive support

Claims (2)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a polysilane compound having a fluorinated alkyl group. 2. The polysilane compound has the following structural formula (1
2. The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is represented by: [Formula 1] (In the formula, R1 to R2 each represent an organic group such as an alkyl group or an aryl group, which may be the same or different, and at least one of them represents a fluorinated group such as a trifluoroethyl group or a perfluorohexyl group. (Represents an organic group having an alkyl group.)