JPS63223753A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To remarkably enhance sensitivity and to elevate durability by dissolving a polycyclic quinone derived pigment and a perylene derived compound into concentrated sulfuric acid, dropping them into water, mixing and precipitating them, and using them for forming an electric charge generating material. CONSTITUTION:The electrophotographic sensitive body is a laminate type formed by laminating the charge generating layer and a charge transfer layer on a conductive supporting body, and the charge generating layer is formed by dissolving the polycyclic quinone derived pigment and the perylene derived compound into concentrated sulfuric acid, dropping them into water, mixing and precipitating them, and using them in an amount of <=80wt.%, preferably, <=40wt.% of the charge generating layer, thus permitting the obtained charge generating layer to enhance its charge generating efficiency, accordingly, the photosensitive body to remarkably enhance sensitivity and not to deteriorate its sensitivity even after repeated uses, and consequently, to enhance durability, too.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to a laminated type electronic photoreceptor comprising a charge generation layer and a charge transport layer provided on a conductive support. It relates to photographic photoreceptors.

[Conventional technology]

Electrophotographic photoreceptors currently in practical use can be roughly divided into those using inorganic photoconductors and those using organic photoconductors.

Typical examples of the above-mentioned inorganic photoconductors include cadmium selenium sulfide and zinc oxide. However, although the above-mentioned inorganic photoconductors have reasonably good properties as photoreceptors, they do not have film-forming properties by themselves, with the exception of a few such as amorphous selenium. It has many drawbacks, such as poor charge retention and is a harmful substance.

On the other hand, as a photoreceptor using an organic photoconductor, for example,
Organic photoconductors made of high molecular substances such as poly-N-vinylcarbazole and polyvinylanthracene, low molecular substances such as hydrazone compounds, birapurin compounds, oxadiazoles, and carbazoles, and phthalocyanine pigments and azo pigments. , cyanine pigments, polycyclic quinone pigments, perylene pigments, indigo pigments, and methine squarate dyes. When the above organic photoconductor is used as a photoreceptor,
The photoreceptor is easy to manufacture, there is a wide range of options for the light absorption wavelength of the photoreceptor, the photoreceptor can be processed into any shape, it is easy to handle, and it is easy to obtain due to the abundance of resources. It has the following advantages. For this reason, development is progressing as a substitute for the inorganic photoconductor, and this trend is expected to become even stronger in the future.

Photoreceptors using organic photoconductors can be roughly classified into the following three types.

(1) A photoreceptor consisting of a photoconductive compound and a sensitizer such as a dye.

(2) A photoreceptor having a photosensitive layer of a charge transfer complex type photoconductive compound.

(3) Functionally separated type consisting of a charge generation layer and a charge transport layer (
Laminated type) photoreceptor.

Even if the photoreceptors in (1) and (2) above are improved versions, they have not yet overcome the drawbacks of organic photoconductors, such as poor sensitivity and poor durability. This is the reality.

On the other hand, the functionally separated type (laminated type) photoreceptor mentioned in (3) above,
Since the charge generation layer and the charge transport layer can be considered independently from a functional standpoint, there is a large degree of freedom when considering materials.
It is expected that this will become the mainstream of photoreceptors in the future.

[Problem that the invention seeks to solve]

However, even with such a functionally separated type (layered type) photoreceptor, in order to produce it with high sensitivity, for example,
It may be necessary to use several types of compounds, such as adding a sensitizer to the charge generation layer, and depending on how these compounds are combined and the mixability of the compounds, the function of the charge generation material can be fully brought out. However, the reality is that it is difficult to put it into practical use because it causes problems such as lack of availability.

[Means for solving problems]

The electrophotographic photoreceptor of the present invention is a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, in which the charge generation layer is formed of a polycyclic quinone pigment and a perylene compound. It is characterized by being formed from a material that is dissolved in concentrated sulfuric acid and dropped into water to mix and precipitate.

The above polycyclic quinone pigment is represented by the structural formula shown below.

The above perylene compound is represented by the structural formula shown below.

The above rRJ is a substituted or unsubstituted alkyl group such as methyl, ethyl, 2-aminoethyl, or phenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 3-aminophenyl, 3.5- diethylphenyl, 3
, 5-diethylphenyl, etc., or unsubstituted phenyl groups, but preferred are perylene compounds in which rRJ is a methyl group.

The above-mentioned conductive support is one in which the base itself has conductivity, such as aluminum, aluminum alloy, copper,
In addition to zinc, stainless steel, nickel, chromium, titanium, etc., plastics have a layer formed by vacuum evaporation of aluminum, aluminum alloy, indium oxide, tin oxide, etc., and conductive particles are impregnated into plastics, paper, etc. A substrate made of aluminum or a plastic material containing a conductive polymer can be used.

The binder used when coating the above mixed and precipitated materials includes insulating resins such as phenoxy resin, polyvinyl butyral, polyacrylate, polycarbonate, polyester, polyvinyl acetate, acrylic resin, urethane resin, and epoxy resin. Can be used. The resin contained in the charge generation layer formed using the mixed and precipitated materials is suitably 80% by weight or less, preferably 40% by weight or less. Furthermore, examples of solvents for dissolving the insulating resin include ethers such as dioxane and tetrahydrofuran, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, benzene, and toluene. Aromatics such as the following can be used.

The charge transport layer is electrically connected to the charge generation,
It has the function of transporting charge carriers injected from the charge generation layer to its surface in the presence of an electric field. As materials for such a charge transport layer, the above-mentioned hydrazone compounds, fluorenone compounds, pyrazoline compounds, oxadiazoles, carbazoles, etc., which belong to low-molecular substances, are used, and among polymer substances, polyamides, etc. are used. -N
-Vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinyl-lene, polyvinylanthracene, etc. are used. When using a low-molecular charge transporting material, a film can be formed by selecting an appropriate binder, such as polycarbonate resin, acrylic resin, polyester, polystyrene, polyvinyl butyral, polyamide, acrylonitrile, etc. - Mention may be made of insulating resins such as styrene copolymers.

[For production]

With the above structure, the charge generation layer improves its charge generation efficiency, so it can significantly improve the sensitivity as a photoreceptor, and also improves its durability, since the sensitivity does not deteriorate even after repeated use. be able to.

[Example 1] An example of the present invention is shown in Figures 1 to 3 and Figure 4 (a).
The explanation will be as follows based on FIG.

For example, as shown in FIG. 1, an electrophotographic photoreceptor includes a conductive support 1, an undercoat layer 112 formed on the conductive support 1, and an undercoat layer 2 formed on the conductive support 1. The charge generating layer 3 is composed of a charge generating layer 3 and a photoconductor consisting of a charge transport Jii 4.The charge generating layer 3 is formed by dissolving a polycyclic quinone pigment and a perylene compound in concentrated sulfuric acid, and then dissolving this in water. It is formed using materials that are mixed and precipitated by dropping.

In order to manufacture the electrophotographic photoreceptor, first, aluminum vapor-deposited PET (Metal Me #100) is used as the conductive support 1.
After applying an aqueous solution of polyurethane in methyl acetate onto the surface (manufactured by Toshi ■) using a coating method, this was dried to a film thickness of 0.
An undercoat layer 2 of 1 μm is formed. The undercoat layer 2 is not limited to the above-mentioned polyurethane, but can also be formed from casein, polyvinyl alcohol, gelatin, aluminum oxide, etc., for example. Moreover, the film thickness is 0.1 to 0.
3 μm is suitable.

Next, dibromoanthuron (Monolite Red 2 Y) as a polycyclic quinone pigment shown in FIG.
: 1.>0.4g manufactured by C,I Company and 0.4g of the perylene compound shown in FIG. 4(a) among the perylene compounds represented by the general structural formula of FIG. 3 in 10rrj! of concentrated sulfuric acid. Mix and dissolve this solution into 20 Qmj! into pure water. At this time, the pure water is added dropwise while stirring and in such a manner that the water temperature does not rise above room temperature. Then, the precipitate produced by this dropping is filtered, washed with pure water, and then dried under reduced pressure to obtain a red crystalline substance. Thereafter, 2 parts by weight of the above crystalline substance and phenoxy resin (PK
HHn (manufactured by UCC) and 97 parts by weight of 1,4-dioxane were dispersed using a ball mill disperser over 12 hours. Next, this dispersion was applied onto the undercoat layer 2 using a Baker applicator and dried to a film thickness of 0.
A charge generation layer 3 having a thickness of 8 μm is formed.

Next, a hydrazone compound shown in FIG. 5 was used as a charge transport material, and 1 part by weight of this hydrazone compound and 1 part of polycarbonate resin (Nipilon: manufactured by Mitsubishi Gas Chemical Co., Ltd.) were added.
parts by weight and 8 parts by weight of dichloromethane are mixed and stirred and dissolved using a stirrer. This solution is applied onto the charge generation layer 3 using a Baker applicator and then dried to form a charge transport layer 4 having a thickness of 18 μm to obtain an electrophotographic photoreceptor.

The electrophotographic photoreceptor manufactured as described above was tested using an electrostatic charging tester (SP-428, manufactured by Kawaguchi Electric ■).
Corona discharge was performed at 5 kV, and the photoreceptor was held for 5 seconds in a dark place, and then exposed to light at an illuminance of 5 Aux to examine the charging characteristics of the photoreceptor.

As a charging characteristic, the exposure amount required to attenuate the initial potential (VO) to 1/2 of the potential when dark decaying for 45 seconds (
El, /Z ), residual potential (V
), and the charge retention rate when dark decayed for 5 seconds (■c
) was measured. Furthermore, in order to repeatedly use the electrophotographic photoreceptor and measure the fluctuations in the bright and dark potentials of the photoreceptor, the electrophotographic photoreceptor was equipped with a 5 kV corona charger and an exposure fi 101 u x -s e C, and the initial bright area potential (Vt, ) and dark area potential (■, ) on the photoreceptor. and 10
00th, 100000000th, Record V.

, Vll were measured, respectively. The measurement results using the electrostatic copying tester are shown in Table 1, and the results of repeated characteristic evaluation are shown in Table 2.

[Examples 2 to 9] In addition to the perylene compounds shown in Figure 4 (a),
Electrophotographic photoreceptors of the same number as those of the first example were manufactured using the perylene compounds shown in FIGS. 10(b) to 12(i), and the same measurements were performed on each of the electrophotographic photoreceptors. The results of each measurement are also shown in Tables 1 and 2 (1,).

Table 1 Note that the above rH-aJ to rJJ-3J are shown in Figure 4 (a
) to (i) correspond to the perylene compounds shown in (i), respectively.

Comparative Example 1 shown in Table 2 In order to clarify the superiority of the charge generation layer according to the present invention, a comparative example is shown below.

In this comparative example, an electrophotographic photoreceptor was manufactured in the same manner as in the above example except that only the polycyclic quinone pigment shown in FIG. 2 was used as the charge generating material. Similar to the above examples, the measurement results using the electrostatic copying tester are shown in Table 3, and the results of repeated characteristic evaluation are shown in Table 4.

Comparative Example 2 In this comparative example, an electrophotographic photoreceptor was produced in the same manner as in the above example except that only the perylene compound shown in FIG. 4(2) was used as the charge generating material. The results are also shown in Tables 3 and 4, respectively.

(Comparative Example 3) In this comparative example, the polycyclic quinone pigment shown in FIG. 2 and the perylene compound shown in FIG. An electrophotographic photoreceptor was manufactured in the same manner as in the above example except for the above.The results are also shown in Tables 3 and 4, respectively.

Table 3 Table 4 As is clear from Tables 1 to 4 above, the electrophotographic photoreceptor of the present invention has important points for improving sensitivity in a functionally separated type (laminated type) electrophotographic photoreceptor. (1) Improvement in charge carrier generation efficiency (2) Improvement in injection efficiency of charge carriers from the charge generation layer to the charge transport layer (3) Improvement in charge carrier transport efficiency among the above (1) We were able to improve the charge carrier generation efficiency as shown in Figure 3, and significantly improve the sensitivity.

Further, as is clear from the above measurement results of the repeatability, the sensitivity does not deteriorate even after repeated use, so an electrophotographic photoreceptor with excellent durability could be obtained.

〔Effect of the invention〕

As described above, the electrophotographic photoreceptor according to the present invention is a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support. It is made of a material in which a pigment and a perylene compound are dissolved in concentrated sulfuric acid, and the solution is dropped into water to mix and precipitate. Therefore, the sensitivity of such an electrophotographic photoreceptor can be significantly improved, and since the sensitivity does not deteriorate even after repeated use, an electrophotographic photoreceptor with excellent durability can be obtained. to play.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view showing one embodiment of the present invention, Figure 2 is a diagram showing the structural formula of a polycyclic quinone pigment, Figure 3 is a diagram showing the general structural formula of a perylene compound, and Figure 4 is a diagram showing the general structural formula of a perylene compound. Figures (a) to (
i) is a diagram showing a specific structural formula of a perylene compound, and FIG. 5 is a diagram showing a Hitotsubashi formula of a hydrazone compound. 1 is a conductive support, 2 is an undercoat layer, 3 is a charge generation layer, 4
is the charge transport layer. Figure 4(a)

Claims (1)

[Claims] 1. In a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer is prepared by dissolving a polycyclic quinone pigment and a perylene compound in concentrated sulfuric acid. 1. An electrophotographic photoreceptor characterized in that it is formed from a material that is mixed and precipitated by dropping it into water.