JPH01234855A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain high sensitivity and low residual potential and to prevent deterioration of characteristics even at the time of repeated uses by using a specified carbazole derivative as an electric charge transfer material. CONSTITUTION:The carbazole derivative to be used as the charge generating material is represented by formula I in which R is vinylene, phenylene, or the like; each of X1-X8 is H, halogen, or 1-4C alkyl, optionally same or different. The charge transfer layer 4 is obtained by dissolving this carbazole derivative in a solvent together with a binder resin, coating a charge generating layer formed in advance, and drying it, thus permitting high transfer efficiency of charge carriers generated in a photosensitive layer, high sensitivity, and low residual potential, and superior successive use stability to be all ensured, without deterioration due to ozone and light exposure.

Description

Detailed Description of the Invention [Summary] The present invention relates to an electrophotographic photoreceptor, in which a novel carbazole derivative is used as a charge transport material for the purpose of obtaining high sensitivity and low residual potential, and reducing the deterioration of characteristics upon repeated use. It is configured to be used as a.

[Conventional technology]

The electrophotographic process consists of charging, exposure, development, transfer, and fixing steps, and printed matter can be obtained by repeating these steps. Charging here applies a uniform positive or negative electrostatic charge to the surface of the photoreceptor having photoconductivity. 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 toner, ie, powder ink, to form a visible toner image on the photoreceptor. Finally, this toner image is electrostatically transferred onto recording paper, and then exposed to heat, light, and
A desired printed material can be obtained by fusing with pressure or the like. Conventionally, inorganic photoreceptors typified by selenium-based photoreceptors have been widely used as photoreceptors having photoconductivity as described above. This inorganic photoreceptor is highly sensitive and resistant to mechanical abrasion, making it suitable for high-speed, large-scale machines. However, it must be manufactured using a vacuum evaporation method and must be collected because it is harmful to the human body. However, due to such reasons, the cost is high and it is difficult to apply it to maintenance-free, small, low-cost machines.

Organic photoreceptors have been developed as an alternative to inorganic photoreceptors. Organic photoreceptors can be manufactured by a coating method, which makes it easy to reduce costs through mass production.Compared to inorganic photoreceptors that use inorganic substances such as selenium, organic photoreceptors have a wider range of materials to choose from, allowing users to choose compounds that are not harmful. It has the advantage of being maintenance-free by being disposed of.

Among these, a functionally separated laminated type photoreceptor (FIG. 1), in which a charge generation layer and a charge transport layer are laminated, is attracting attention. Here, the charge generation layer has the function of absorbing incident light and generating electron-hole pairs (carrier pairs), and the charge transport layer holds charges on its surface and carries carriers generated in the charge generation layer. It has the function of transporting one side of the photoreceptor to the surface of the photoreceptor to form an electrostatic latent image. The charge generation layer may be a vapor-deposited film of a charge generation substance that actually absorbs light and generates carrier pairs, or
Alternatively, it is formed by dispersing it in a binder resin. Phthalocyanine, azo pigments, 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 is formed by dissolving a charge transport material having carrier transport ability in a binder resin. Charge transport materials include electron transport charge transport materials such as trinitrofluorenone, 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. As the material, polycarbonate, styrene-acrylic, etc. are used.

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. It is possible to dramatically improve properties such as wear resistance.

[Problem to be solved by the invention]

However, organic photoreceptors still have lower sensitivity than inorganic photoreceptors such as selenium, making it difficult to apply them to high-speed printers. In addition, as the charging-exposure process is repeated, the charge transporting material is degraded by ozone and irradiation light generated during charging, and there is a problem that printing quality is degraded due to a decrease in charging potential and an increase in residual potential.

[Means to solve the problem]

The above-mentioned problems can be solved by using the electrophotographic photoreceptor of the present invention, that is, by using a novel carbazole derivative represented by the following structural formula 1 as a charge transport material.

(In the formula, R is vinylene (-CII=CH-), phenyleX l-X a may be the same or different, hydrogen, halogen, 01-c4 alkyl group, 01
~C4 alkoxy group, aryl group, c1-C4 aralkyl group, CI-C4 alkylamino group, arylamino group, C1-C4 aralkylamino group.

As the charge generating substance, various metal phthalocyanines and azo pigments can be used, such as metal-free phthalocyanine, copper phthalocyanine, aluminum chloride phthalocyanine, titanyl phthalocyanine, vanadyl phthalocyanine, and indium phthalocyanine. The charge generating layer can be 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. The binder resin for the charge generation layer is selected from polyester, polyvinyl alcohol, polyvinyl butyral, polyamide, etc., taking into consideration the adhesion to the base and the dispersibility of the charge generation substance. The solvent is selected according to the charge generating substance and binder resin used, but examples include tetrahydrofuran, dioxane, methanol,
Various organic solvents such as ethanol, dichloromethane, dichloroethane, toluene, and xylene can be used alone or in combination. Methods for coating the support include dip coating, spray coating, wire barcode coating, and doctor blade coating. The film thickness is 0.01 to 3 tones, but it is particularly desirable to have an IJ of 1 m or less.

Examples of the conductive support include metals such as aluminum and copper, and resins imparted with conductivity by adding tin oxide, carbon, and the like.

Examples of the carbazole derivative of the present invention used as a charge transport substance include the following compounds.

1 company 2 Nn 5 (m, p, 210°) lh6 floor 7 floor 10 11hll 15 16 l1lT 18! 1h32 隘33 l134 11h35 11h36 1'1k14 υ N[L42 Fish 48 # 49 (m, p, 260℃) rl n! 1h52 1'1kLb υ Floor 64 NIEi8 Nn 69 (m, p, 300°) rρ 1m72 Nl18 υ The carbazole derivative has, for example, the following formula ■: C1-C0,-x-cnzc* (II
) and the compound represented by the following formula (■): (wherein, X and ~Xa may be the same or different, hydrogen, halogen, CI-C4 alkyl group, 0
It represents a 1-C4 alkoxy group, an aryl group, a C1-C4 aralkyl group, a CI-Ca alkylamino group, an arylamino group, and a CI""Ca aralkylamino group. ) can be easily obtained by reacting a compound represented by:

The above reaction can be carried out, for example, as follows.

First, a carbazole salt is prepared from the carbazole compound (2) using, for example, potassium hydroxide.

Next, add the salt to the dihalide at about 80-120℃ for 1 hour.
By heating for ~3 hours, the compound of formula (1) above can be obtained in high yield. The molar amounts of K salt and dihalide used are 2:1.

The charge transport layer can be obtained by dissolving the above-mentioned carbazole derivative together with a binder resin in a solvent, coating the solution on the previously formed charge generation layer, and drying the solution.

As the binder resin for the charge transport layer, known binder resins such as polycarbonate, polystyrene, polyacrylonitrile, acrylic-styrene, polyester, and polysulfone can be used. As in the case of the charge generation layer, the solvent is appropriately selected depending on the binder resin used. As for the coating method, the same method as in the case of the charge generation layer can be used. The film thickness is 5 to 50 m, preferably 10 to 25 m.

During charge transport, other charge transport substances such as hydrazone derivatives and pyrazoline derivatives may be added in addition to the carbazole derivative (1).

Further, the stacking order of the charge generation layer and the charge transport layer may be reversed.

Further, an undercoat layer may be provided between the support and the photosensitive layer in order to improve adhesion, prevent thermal carrier injection, and the like. As the undercoat layer, resins such as polyvinyl alcohol, polyvinyl butyral, polyamide, and epoxy, or resins containing additives such as tin oxide, indium oxide, and titanium oxide are used.

[For production]

The electrophotographic photoreceptor of the present invention improves the transport efficiency of charge carriers generated in the photosensitive layer by containing carbazole derivative I having excellent hole transport properties in the photosensitive layer, thereby achieving high sensitivity and low residual potential. This has been achieved. Furthermore, the carbazole derivative I of the present invention exhibits excellent continuous stability because it is hardly susceptible to deterioration even by ozone or light irradiation.

〔Example〕

1.12g of KOH in a 200mj flask (20mm
oJ), methoxycarbazole 3.94 g (2
0mmo1) Add 100mZ of xylene and heat at 120℃ for 2
The mixture was stirred while heating for an hour. Subsequently, 12.5 g (10 mmo#) of 1,4-dichlorobutene was added, and 110
The mixture was stirred while heating at ℃ for 4 hours. Subsequently, xylene was concentrated and distilled off, and the obtained solid was recrystallized from methanol. Yield: 15g.

Other carbazole derivatives with a melting point of 140°C were synthesized under the same conditions, only the raw materials were changed.

Amount of carbon: 1 part of aluminum chloride phthalocyanine (overlapping part), 1 part of polyester, and 18 parts of dichloromethane were dispersed and mixed for 24 hours using hard glass beads and a hard glass pot, and then mixed with a doctor blade on the aluminum surface of the aluminum vapor-deposited polyester film. It was coated and dried at 100° C. for 1 hour to form a charge generation layer with a thickness of about 0.3 mm.

Next, 1 part of the carbazole derivative (lIh1) and 1 part of polycarbonate were dissolved in 9 parts of tetrahydrofuran, and the solution was applied onto the previously formed charge generation layer using a doctor blade, and dried at 80°C for 2 hours to form a film with a thickness of approximately A 18-charge transport layer was formed. In this way, a photoreceptor as shown in FIG. 1 was obtained.

Next, this photoreceptor was corona charged at 15 kV, and 1
■ Surface potential after seconds. 780 from that moment as (V)
Exposure was performed with light of nm. Find the time t,/2 for the surface potential to become half of Vo, and calculate the halving exposure amount El/2.
(μJ/J) was calculated. Furthermore, 10t+ after the start of exposure
Record the surface potential Vr (V) of z□, and finally 633 nm
One process was completed by eliminating static electricity using the LED. Table 1 shows the results of repeating this process 100 times.

Example 2 except that carbazole derivative N112 was used instead of carbazole derivative t1 as the charge transport material.
Exactly the same method was used. The results are shown in Table 1.

■Soil The same method as in Example 2 was carried out except that carbazole derivative A3 was used instead of carbazole derivative A1 as the charge transport material.゛The results are shown in Table 1.

l The same procedure as in Example 2 was carried out except that carbazole derivative N14 was used instead of carbazole derivative N14 as the charge transport material. The results are shown in Table 1.

Example 1 (Comparative Example) The same procedure as in Example 1 was carried out except that hydrazone represented by the following structural formula was used instead of the carbazole derivative 1 as a charge transport substance. The results are shown in Table 1.

1- 1 part (by weight) of aluminum chloride phthalocyanine
, polyester, and 18 parts of dichloromethane were dispersed and mixed for 24 hours using hard glass beads and a hard glass pot, and then applied with a doctor blade onto the aluminum surface of the aluminum-deposited polyester film, and dried at 100°C for 1 hour to form a film. A charge generation layer having a thickness of about 0.3 - was formed.

Next, 1 part of the above carbazole derivative (m41) and 1 part of polycarbonate were dissolved in 9 parts of tetrahydrofuran, and the solution was coated on the previously formed charge generation layer with a doctor blade and dried at 80°C for 2 hours to give a film thickness of about 18JIm. A charge transport layer was formed. In this way, a photoreceptor as shown in FIG. 1 was obtained.

Next, this photoreceptor was corona charged at 15 kV, and 1
■ Surface potential after seconds. 780 from that moment as (V)
Exposure was performed at nm, 1 μ-/cJ. The surface potential is vo
Find the time tl/□ to reduce to half, and calculate the halved exposure amount E.
l/2 (μJ/aJ) was calculated. Furthermore, the surface potential Vr (V) of 10 t I7t after the start of exposure was recorded,
Finally, one process was completed by eliminating static electricity using a 633 nm LED. The result of repeating this process 10,000 times is the second
Shown in the table.

■1 Example 7 except that carbazole derivative 42 was used instead of carbazole derivative 41 as the charge transport material.
and all (a similar method was carried out. The results are shown in Table 2.

■Work Example 7 except that carbazole derivative tooth 43 was used instead of carbazole derivative tooth 41 as the charge transport material.
Exactly the same method was used. The results are shown in Table 2.

■Carbazole derivative Hato 41 as a charge transport substance
Exactly the same procedure as in Example 7 was carried out, except that the carbazole derivative 1'h44 was used instead of . The results are shown in Table 2.

Open soil (comparative example) The same procedure as in Example 7 was carried out except that hydrazone represented by the following structural formula was used instead of the carbazole derivative 11h41 as the charge transport substance. The results are shown in Table 2.

■Top Yu 1 part (by weight) of aluminum chloride phthalocyanine, 1 part of polyester, and 18 parts of dichloromethane were dispersed and mixed for 24 hours using hard glass beads and a hard glass pot, and then applied with a doctor blade onto the aluminum surface of the aluminum vapor-deposited polyester film. It was coated and dried at 100° C. for 1 hour to form a charge generation layer with a thickness of about 0.3 mm.

Next, the above carbazole derivative (ffi61) 1
1 part of polycarbonate was dissolved in 9 parts of tetrahydrofuran, and the solution was coated on the previously formed charge generation layer with a doctor blade and dried at 80 DEG C. for 2 hours to form a charge transport layer having a thickness of about 18 cm. In this way, a photoreceptor as shown in FIG. 1 was obtained.

Next, this photoreceptor was corona charged at 15 kV, and 1
■ Surface potential after seconds. 780 from that moment as (V)
Exposure was performed at nm, lμw/ruJ. The surface potential is v
The time tl/□ until half of o was obtained, and the half-reduction exposure amount El/□ (μJ/-) was calculated. Furthermore, after the start of exposure, a surface potential Vr (V) of 10 t +/l was recorded, and finally, the static electricity was removed using a 633 nm LED to complete one process.

Table 3 shows the results of repeating this process 10,000 times.

■Earthwork Carbazole derivative m61 as a charge transport material
Exactly the same procedure as in Example 13 was carried out, except that the carbazole derivative A62 was used instead of.

The results are shown in Table 3.

■Earthwork Carbazole derivative magnet 61 as a charge transport material
A procedure similar to that of Example 13 was carried out except that the carbazole derivative N163 was used instead of .

The results are shown in Table 3.

, LLfi - Carbazole derivative instead of carbazole derivative 61 as charge transport material! Exactly the same procedure as in Example 13 was carried out, except that 'h64 was used.

The results are shown in Table 3.

1 (Comparative Example) The same procedure as in Example 13 was carried out except that hydrazone represented by the following structural formula was used in place of the carbazole derivative 61 as a charge transport substance. The results are shown in Table 3.

As can be seen from Tables 1 to 3, the photoreceptor of the present invention has 1
0000 @ There is almost no deterioration in characteristics even after repeated tests. On the other hand, the photoreceptor of the comparative example may show relatively good characteristics in the initial stage, but after continuous testing, the photoreceptor deteriorates with a decrease in charging potential and sensitivity, and an increase in residual potential. or fatigue).

〔Effect of the invention〕

As explained above, since the present invention is configured to use the carbazole derivative I of the present invention as a charge transport substance, high sensitivity and low residual potential can be obtained, and
It is possible to obtain an electrophotographic photoreceptor whose characteristics do not deteriorate even after repeated use.

[Brief explanation of the drawing]

FIG. 1 shows an example (cross-sectional view) of the structure of the photoreceptor of the present invention, and in the figure, 1-photosensitive layer, 2-charge transport layer, 3-
A charge generation layer and a 4-support are shown, respectively. Structure diagram of the photoreceptor of the present invention 1...Photosensitive layer 2...Charge transport layer 3...Charge generation layer 4...Support

Claims (1)

[Scope of Claims] A laminated photoreceptor having at least a charge generation layer and a charge transport layer on a conductive support, the charge transport layer containing at least a carbazole derivative represented by the following structural formula I as a charge transport substance. An electrophotographic photoreceptor characterized by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R is vinylene (-CH=CH-), phenylene▲There are mathematical formulas, chemical formulas, tables, etc.▼, naphthalene▲There are mathematical formulas, chemical formulas, tables, etc. ▼ or anthrylene ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and X_1 to X_6 may be the same or different, and hydrogen, halogen, C_1 to C_4 alkyl group,
_1-C_4 alkoxy group, aryl group, C_1-C_
It represents a 4-aralkyl group, a C_1-C_4 alkylamino group, an arylamino group, and a C_1-C_4 aralkylamino group.