JP2612345B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoconductor for electrophotography. More specifically, the present invention relates to an electrophotographic photoreceptor characterized in that a photosensitive layer on a conductive support contains a novel compound as a charge transporting substance.

[Conventional technology]

Conventionally, inorganic photosensitive materials such as selenium, cadmium sulfide, and zinc oxide have been widely used as photosensitive materials for electrophotographic photosensitive members. However, photoreceptors using these photosensitive materials have not sufficiently satisfied the required performance as an electrophotographic photoreceptor, such as sensitivity, light stability, moisture resistance, and durability. For example, a photoreceptor using a selenium-based material has excellent sensitivity, but is easily crystallized due to heat or adhesion of dirt, and the characteristics of the photoreceptor are easily deteriorated. In addition, it has many drawbacks such as high cost because it is manufactured by vacuum evaporation, and difficulty in processing it into a belt shape due to lack of flexibility. A photoreceptor using a cadmium sulfide-based material has a problem in moisture resistance and durability, and a photoreceptor using zinc oxide has a problem in durability.

In order to overcome the disadvantages of the photoreceptor using the inorganic photosensitive material, various photoreceptors using the organic photosensitive material have been studied.

In recent years, among photoconductors developed to improve the above-mentioned disadvantages, a function-separated type photoconductor in which a charge generation function and a charge transport function are shared by different substances has been receiving attention. In this function-separated type photoreceptor, substances having respective functions can be selected from a wide range and combined, so that a photoreceptor having high sensitivity and high durability can be manufactured.

Electrophotographic properties required for charge transport materials (1)
The ability to accept the charge generated by the charge-generating substance is sufficiently high, (2) The transport of the received charge is rapid, (3) The charge is sufficiently transported even in a low electric field, and no charge remains. There is.

Further, the photoreceptor is required to be stable against light, heat, and the like received in the repetitive steps of charging, exposing, developing, and transferring during copying, and to have durability for obtaining a copied image with reproducibility faithful to the original image.

Various compounds have been proposed as charge transport materials. For example, poly-N-vinylcarbazole has long been known as a photoconductive substance, and a substance using this as a charge transporting substance has been put to practical use. However, the poly-N-vinyl carbazole itself has poor flexibility, is fragile, and causes cracks. The durability was inferior to repeated use because it was easy. Further, when the flexibility is improved in combination with the binder, there is a disadvantage that the electrophotographic properties are inferior.

On the other hand, a low-molecular compound generally does not have a film property, and is usually mixed with a binder with an arbitrary composition to form a photosensitive layer. Many charge transport materials have been proposed as low molecular compounds. For example, a hydrazone compound has high sensitivity as a charge transporting substance,
-46761, JP-A-55-52064, JP-A-57-58156,
It is described in JP-A-57-58157 and the like. However, these have a problem of decomposition by ozone generated during corona charging, or stability against light and heat.Although the initial performance is excellent, the charge retention ability is reduced by repeated use, or the residual potential is accumulated. Due to the cause, the image has a low contrast or a lot of fog.

Many other charge transport materials have been proposed, but none of them practically satisfies the required performance of electrophotographic photoconductors, and the development of even better photoconductors has been desired. .

[Problems to be solved by the invention]

An object of the present invention is to provide an electrophotographic photoreceptor having sufficient sensitivity and good durability. Another object of the present invention is to provide a novel charge transport material used for the same.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the general formula (I) [In the formula (I), -A- is a divalent linking group, preferably a substituted or unsubstituted phenylene group, a bisphenylene group, a naphthylene group, or (Where X is an oxygen atom, a sulfur atom or R ⁵ and R ⁶ are a hydrogen atom, an optionally substituted alkyl group or an optionally substituted aryl group, and R ⁵ and R ⁶ may be bonded to each other. )
R ¹ , R ² , R ³ and R ⁴ are an unsubstituted or substituted aryl group, and R ¹ R ² , R ³ and R ⁴ may be bonded to each other. n is 0
Or represents an integer of 1. The present invention has been found to provide a novel electrophotographic photoreceptor having excellent characteristics such as high sensitivity and high durability. Since the compound of the present invention has a long molecular length, it is more effective in transferring holes than a short molecule.

That is, the present invention is an electrophotographic photosensitive member, characterized in that the photosensitive layer on the conductive support contains the compound represented by the general formula (I).

In -A- in the general formula (I), examples of the phenylene group include And examples of biphenylene groups include And examples of naphthylene groups include And the like, An example of And the like.

Substituted phenylene, biphenylene, naphthylene, Examples of the substituent include a halogen atom such as Cl-, Br- and I-, an alkyl group such as a methyl group, an ethyl group and a propyl group, and an alkoxy group such as a methoxy group, an ethoxy group and a propoxy group. .

In R ⁵ and R ⁶ , examples of the alkyl group include a methyl group, an ethyl group, and a propyl group.Examples of the aryl group include a phenyl group and a naphthyl group. And an alkyl group such as methoxy group and ethoxy group, and a dialkylamino group such as dimethylamino group and diethylamino group. Further, as a group in which R ⁵ and R ⁶ are bonded, And the like.

Examples of the aryl group of R ¹ , R ² , R ³ and R ⁴ include a phenyl group and a naphthyl group, and examples of the substituent include a methyl group, an alkyl group such as an ethyl group, a methoxy group,
Examples include an alkoxy group such as an ethoxy group, a halogen atom such as a chlorine atom and a bromine atom, and a dialkylamino group such as a dimethylamino group and a diethylamino group. R ¹ and
As the group in which R ² , R ³ and R ⁴ are bonded, And the like.

The compounds that can be used in the present invention are more specifically shown in Table 1, but the compounds that can be used in the present invention are not limited to these.

The compound represented by the general formula (I) is, for example, R ¹ =
R ³ , R ² , and R ⁴ can be synthesized as follows.

Wherein (IV), R ^1, R ² is identical to R ^1, R ² of general formula (I). And a molar ratio of 2 to the aldehyde compound represented by the general formula (V) H ₂ N-A-NH ₂ (V) [wherein -A- is the same as -A- in the general formula (I). It is. In a suitable solvent (eg, ethyl alcohol, toluene) in the presence of an acid such as acetic acid.

The compound of the present invention is used as a charge transporting material in combination with a charge generating material to constitute an electrophotographic photoreceptor.

As the charge generating substance, any substance having a charge generating ability can be used.Inorganic materials such as selenium, selenium alloy, amorphous silicon, cadmium sulfide and the like, and phthalocyanine, perylene, perinone, indigo, anthraquinone , Cyanine, azo and other organic dyes,
Pigments and the like can be exemplified. Among them, a phthalocyanine-based charge-generating material represented by the following general formula (III) and an azo-based charge-generating material represented by the following general formula (II) are suitable for use in combination with the charge transporting material of the present invention.

The following general formula (II) [In the formula (II), B is Or And Ar- represents an unsubstituted or substituted aryl group. Examples of the aryl group in Ar- in the formula include a phenyl group, a naphthyl group and an anthryl group, and examples of the substituent include an alkyl group such as a methyl group, an ethyl group and a propyl group, a methoxy group and an ethoxy group. Group, alkoxy group such as propoxy group, halogen atom such as fluorine atom, chlorine atom, bromine atom, halomethyl group such as trifluoromethyl group, dialkylamino group such as dimethylamino group, diethylamino group, nitro group, cyano group, carboxyl group Groups or esters thereof.

The following general formula (III) [In the formula (III), Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ , Y ⁶ , Y ⁷ , Y ⁸ ,
Y ⁹ , Y ¹⁰ , Y ¹¹ , Y ¹² , Y ¹³ , Y ¹⁴ , Y ¹⁵ and Y ¹⁶ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, or the like. And M represents two hydrogen atoms or divalent metal atoms, monosubstituted trivalent metal atoms, disubstituted tetravalent metal atoms or oxymetal atoms. , Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ ,
^{Y 6, Y 7, Y 8} , Y 9, Y 10, Y 11, Y 12, Y 13, Y 14, Y 15 and Y
^{As 16} , a halogen atom such as a chlorine atom and a bromine atom,
Methyl group, ethyl group, n-propyl group, n-butyl group,
n-aluminum group, n-hexyl group, iso-propyl group, ter
t-butyl group, iso-butyl group, iso-amyl group, neo-pentyl group, 2-ethyl-hexyl group, 3,5,5-trimethylhexyl group, alkyl group such as methoxymethyl group, methoxy group, ethoxy group , N-propoxy group, n-butoxy group, n-amyloxy group, n-hexyloxy group, is
o-propyloxy group, tert-butoxy group, iso-butoxy group, iso-amyloxy group, neo-pentyloxy group,
2-ethyl-hexyloxy group, 3,5,5-trimethylhexyloxy group, alkoxy group such as methoxyethoxy group, phenoxy group, aryloxy group such as 4-tert-butylphenyloxy group, methylthio group, ethylthio group, Examples thereof include an alkylthio group such as an n-propylthio group and an iso-propylthio group, and an arylthio group such as a phenylthio group, a 4-tert-butylphenylthio group, and a naphthylthio group.

As M, Cu ^(II) , Zn ^(II) ,
Fe ^(II) , Co ^(II) , Ni ^(II) , Ru ^(II) , Rh ^(II) , Pd ^(II) , Pt
^(II) , Mn ^(II) , Mg ^(II) , Ti ^(II) Be ^(II) , Ca ^(II) , B
a ^(II) , Cd ^(II) , Hg ^(II) , Pb ^(II) , Sn ^{(II) and the} like.

Examples of the monosubstituted trivalent metal include Al-Cl, Al-Br, Al-
F, Al-I, Ca-Cl, Ga-F, Ga-I, Ga-Br, In-C
l, In-Br, In-I, In-F, Tl-Cl, Tl-Br, Tl-
I, Tl-F, Fe- Cl, Ru-Cl, Al-C 6 H 5, Al-C 6 H 4 (CH
_{3), In-C 6 H} 5, In-C 6 H 4 (CH 3), In-C 10 H 7, Mn (O
H), Mn (OC ₆ H ₅ ), Mn [OSi (CH ₃ ) ₃ ] and the like.

Examples of disubstituted tetravalent metals include CrCl ₂ , SiCl ₂ , SiBr
_{2, SiF 2, SiI 2,} ZrCl 2, GeCl 2, GeBr 2, GeI 2, GeF 2, Sn
Cl ₂ , SnBr ₂ , SnI ₂ , SnF ₂ , TiCl ₂ , TiBr ₂ , TiF ₂ , Si (O
H) ₂ , Ge (OH) ₂ , Zr (OH) ₂ , Mn (OH) ₂ , Sn (O
H) ₂ , TiR ₂ , CrR ₂ , SiR ₂ , SnR ₂ , GeR ₂ [R represents an alkyl group, a phenyl group, a naphthyl group and derivatives thereof], Si (OR ′) ₂ , Sn (OR ′) ₂ , Ge (OR ') ₂ , Ti
(OR ′) ₂ , Cr (OR ′) ₂ [R ′ represents an alkyl group, a phenyl group, a naphthyl group, a trialkylsilyl group, a dialkylalkoxysilyl group and a derivative thereof], Sn (S
R ″) ₂ , Ge (SR ″) ₂ [R ″ represents an alkyl group, a phenyl group, a naphthyl group and derivatives thereof] and the like.

Examples of oxymetals include VO, MnO, TiO, and the like.

Since the compound of the present invention has no film-forming ability by itself, it forms a photosensitive layer in combination with a binder. As the binder, an insulating polymer is used, and examples thereof include polystyrene, polyacrylamide, polyvinyl chloride, polyester resin, polycarbonate resin, epoxy resin, phenoxy resin, and polyamide resin.

In particular, polyester resins and polycarbonate resins can be suitably used. In addition, poly-N-vinyl carbazole having its own charge transporting ability can also be used as a binder.

The structure of the photoreceptor is such that a charge generating substance and a charge transporting substance are contained in the same layer on a conductive support as shown in FIG. 1, and on a conductive support as shown in FIG. There are a charge-generating layer containing a charge-generating substance, a charge-transporting layer containing a charge-transporting substance laminated thereon, and a charge-generating layer and a charge-transporting layer laminated in reverse. Any of the photoreceptors having the above-mentioned constitution is effective for the present invention, but the laminated photoreceptor shown in FIG. 2 is preferable in that excellent electrophotographic characteristics can be obtained.

 The structure of the photoconductor will be described in more detail with reference to FIG.

As the conductive support, aluminum, copper, a metal plate such as zinc, aluminum, those that have been deposited conductive material SnO ₂ or the like or a conductive-treated paper, resin or the like is used in a plastic sheet or a plastic film such as polyester You.

To form the charge generation layer, a method of vacuum-depositing a charge generation substance on a conductive support, a method of applying and drying a solution of the charge generation substance, a method of applying and drying a fine particle dispersion of the charge generation substance, etc. The charge generation layer can be formed by using the charge generation material and selecting an arbitrary method. The thickness of the charge generation layer is preferably 0.01 to 5 μm,
More preferably, it is 0.05 to 2μ. This thickness is 0.01μ
If it is less than 5 μm, the generation of electric charge is not sufficient, and if it exceeds 5 μm, the residual potential is high, which is not practically preferable.

The charge transport layer is formed by mixing and dissolving at least one compound of the present invention and the binder in an appropriate organic solvent, coating and drying. A charge transport material other than the compound of the present invention may be added to the charge transport layer and used in combination with the compound of the present invention. The charge transport layer contains a charge transport material in an amount of 10 to 95% by weight, preferably 30 to 90% by weight. When the amount of the charge transporting substance is less than 10% by weight, the charge is hardly transported, and when the amount exceeds 95% by weight, the mechanical strength of the photoreceptor is poor, which is not practically preferable.

The thickness of the charge transport layer is preferably 3 to 50 μm, more preferably 5 to 30 μm, and the thickness is 3 μm.
If it is less than 50 μm, the charge amount is insufficient, and if it exceeds 50 μm, the residual potential is high, which is not preferable for practical use.

In addition, an intermediate layer can be provided between the photosensitive layer and the conductive support, but the material is suitably polyamide, nitrocellulose, casein, polyvinyl alcohol, and the like.
The thickness is preferably 1 μm or less.

As described above, the electrophotographic photoreceptor of the present invention comprises the above-mentioned conductive support, a charge-generating substance, a binder and the like in addition to the compound of the general formula (I). Is not particularly limited as long as it has a function as a component of the photoreceptor.

[Action and effect]

The electrophotographic photoreceptor of the present invention has high sensitivity and excellent performance which does not deteriorate in repeated use by using the compound represented by the general formula (I) as a charge transporting substance.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the embodiments of the present invention are not limited thereto.

Production Example 1 Synthesis of Exemplified Compound No. 1 The following structural formula To a mixture of 4.51 g of the compound represented by the formula and 100 cc of ethanol were added 0.25 g of hydrazine monohydrate and 3 cc of acetic acid, and the mixture was heated under reflux at room temperature for 2 hours and further for 1 hour. After concentrating the reaction solution, recrystallization (a mixed solvent of toluene and ethanol), followed by washing with ethanol and drying were performed to obtain 3.6 g of crystals.
This was confirmed to be Exemplified Compound No. 1 from the elemental analysis values.

Elemental analysis value CHN Calculated value (%) 88.16 5.61 6.23 Actual value (%) 88.10 5.57 6.20 Production Example 2 Synthesis of Exemplified Compound No. 2 In a mixture of 9.02 g of the compound represented by
1.08 g of 4-phenylenediamine and 5 cc of acetic acid were added, and the mixture was heated under reflux for 3 hours. The precipitated crystals were filtered by suction, washed with ethanol, recrystallized (using toluene and ethanol), and then dried to obtain 7.0 g of crystals. This was confirmed to be Exemplified Compound No. 2 from the elemental analysis values.

Elemental analysis value CHN Calculated value (%) 88.67 5.58 5.74 Actual value (%) 88.63 5.57 5.71 Example 1 Polyester resin (manufactured by Toyobo, trade name "Vylon 20")
0 ") 0.5 g, disazo dye 0.5 g represented by the following structural formula
(CG-1) (However, Expression B is It is. ) And 50 g of tetrahydrofuran were pulverized and mixed by a ball mill, and the obtained dispersion was applied to an aluminum plate using a wire bar, and dried at 80 ° C for 20 minutes to form a charge generation layer of about 0.5 µ.

A solution of 1 g of Exemplified Compound No. 1 and 1 g of a polycarbonate resin (trade name “Panlite K-1300” manufactured by Teijin Chemicals) in 10 parts of chloroform was applied on the charge generation layer using a wire bar. The resultant was dried to form a charge transporting layer having a thickness of about 18 μm, thereby producing a laminated photoreceptor shown in FIG.

Electrostatic copying paper test equipment (model manufactured by Kawaguchi Electric Works, Ltd.)
EPA-8100) was charged by corona discharge of the applied voltage -6KV the photoconductor was measured using a surface potential V ₀ at that time, then allowed to stand in a dark place for 2 seconds, to measure the surface potential V ₂ at that time,
Further, when the surface illuminance of the photoreceptor is 5 lux, the light is irradiated from a halogen lamp (color temperature: 2856 照射 K) so that the surface potential becomes V.
Measure the time to become 1/2 of ₂ and calculate the half-life exposure amount E1 / 2 (lux
c) was calculated. The surface potential V ₁₂ after 10 seconds of light irradiation, that is, the residual potential was measured. Further, the operation of charging exposure was repeated 1000 times.

Example 2 Disazo dye represented by the following structural formula (CG-2) (However, B in the formula is It is.

Was used as a charge generating material, and Exemplified Compound No. 1 was used as a charge transporting material, respectively. A photoconductor was prepared in the same manner as in Example 1, and the same measurement was performed.

Example 3 Disazo dye represented by the following structural formula (CG-3) (However, B in the formula is It is. ) Was used as a charge generating substance, and Exemplified Compound No. 1 was used as a charge transporting substance, except that a photoreceptor was prepared in the same manner as in Example 1 and the same measurement was performed.

Example 4 Tetrakisazo dye represented by the following structural formula (CG-4) (However, A in the formula is It is. ) Was used as a charge generating substance, and Exemplified Compound No. 1 was used as a charge transporting substance, except that a photoreceptor was prepared in the same manner as in Example 1 and the same measurement was performed.

Example 5 A sample was prepared in the same manner as in Example 1 except that τ-phthalocyanine (CG-5) was used as a charge generating substance and Exemplified Compound No. 1 was used as a charge transporting substance, and the same measurement was performed.

Examples 6 to 30 Photoconductors were prepared in the same manner as in Example 1 except that the charge generating substance and the charge transporting substance were changed, and the same measurement was performed.

Table 2 shows the combinations of the charge generating substances and the charge transport substances used and the measurement results together with the measurement results of Examples 1 to 5.

Comparative Example 1 Except that the above disazo dye (CG-3) was used as a charge generating substance and 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole (CT-1) was used as a charge transporting substance. A photoconductor was prepared in the same manner as in Example 1, and the same measurement was performed. Table 2 shows the measurement results.

Examples 31 to 33 The photoconductors prepared in Examples 4, 5 and 9 were respectively mounted on a commercially available electrophotographic copying machine and copied. Even on the 10,000th sheet, a clear image without fogging which was faithful to the original image was obtained. Obtained.

As described above, it can be said that the electrophotographic photoreceptor using the compound of the present invention has high sensitivity, stable performance even after repeated use, and excellent durability.

The photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for various printers applying the electrophotographic copying principle,
It can be widely used in electrophotographic plate making systems.

[Brief description of the drawings]

FIG. 1 and FIG. 2 are cross-sectional views showing a configuration example of an electrophotographic photosensitive member. In FIG. 1 and FIG. 2, each symbol is as follows. DESCRIPTION OF SYMBOLS 1 ... Conductive support, 4,4 '... Photosensitive layer 2 ... Charge generation material 5, ... Charge transport layer 3 ... Charge transport material, 6 ... Charge generation layer

Claims (6)

(57) [Claims] 1. A photosensitive material comprising a charge transporting substance and a charge generating substance in a photosensitive layer on a conductive support, wherein [In the formula (I), -A- represents a divalent linking group, and R ¹ , R ² ,
R ³ and R ⁴ is an unsubstituted or substituted aryl group, and R ¹
R ² , R ³ and R ⁴ may be linked to each other. n represents an integer of 0 or 1. ] A photoreceptor for electrophotography, comprising a compound represented by the formula (1) as a charge transporting substance. 2. The method according to claim 1, wherein the divalent linking group represented by -A- in the formula (I) is a substituted or unsubstituted phenylene group, biphenylene group,
Naphthylene group or (Where X is an oxygen atom, a sulfur atom or R ⁵ and R ⁶ are a hydrogen atom, an optionally substituted alkyl group or an optionally substituted aryl group, and R ⁵ and R ⁶ may be bonded to each other. 2. The electrophotographic photoreceptor according to claim 1, wherein the compound represented by the formula (1) is used as a charge transporting substance. 3. A charge-generating substance represented by the following general formula (II): [In the formula (II), B is Or And Ar- represents an unsubstituted or substituted aryl group. The electrophotographic photoreceptor according to claim 1, wherein a compound represented by the following formula is used. 4. The following general formula (III): [In the formula (III), Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ , Y ⁶ , Y ⁷ , Y ⁸ ,
Y ⁹ , Y ¹⁰ , Y ¹¹ , Y ¹² , Y ¹³ , Y ¹⁴ , Y ¹⁵ and Y ¹⁶ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group. , M represents two hydrogen atoms or divalent metal atoms, monosubstituted trivalent metal atoms, disubstituted tetravalent metal atoms or oxymetal atoms. The electrophotographic photoreceptor according to claim 1, wherein a compound represented by the following formula is used. 5. A compound represented by the following general formula (II): [In the formula (II), B is Or And Ar- represents an unsubstituted or substituted aryl group. 3. The electrophotographic photoreceptor according to claim 2, wherein a compound represented by the following formula is used. 6. A charge-generating substance represented by the following general formula (III): [In the formula (III), Y ¹ , Y ² , Y ³ , Y ⁴ , Y ⁵ , Y ⁶ , Y ⁷ , Y ⁸ ,
Y ⁹ , Y ¹⁰ , Y ¹¹ , Y ¹² , Y ¹³ , Y ¹⁴ , Y ¹⁵ and Y ¹⁶ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group. , M represents two hydrogen atoms or divalent metal atoms, monosubstituted trivalent metal atoms, disubstituted tetravalent metal atoms or oxymetal atoms. 3. The electrophotographic photoreceptor according to claim 2, wherein a compound represented by the following formula is used.