Patent Application
20080080895
These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Throughout the drawings, the same reference numerals will be understood to refer to the same elements, features, and structures.
Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.
According to an exemplary embodiment of the present general inventive concept, a photoconductor of an electrophotographic image forming apparatus using a short-wavelength light source includes a supporter and a photoconductive layer which is formed on the supporter. The photoconductive layer includes a naphthalenetetracarboxylic acid diimide derivative represented by the following Formula (I),
in which, R1, R2, and R3 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C6 to C30 aryl group, and a substituted or unsubstituted C7 to C30 aralkyl group.
Examples of the naphthalenetetracarboxylic acid diimide derivative represented by the following Formula (I) may include one of compounds represented by the following Formulae (II) to (VIII),
The compound of Formula (II) has an absorbance which is reduced to very close to 0 from approximately 400 nm in the wavelength of the light emitted from the light source, and accordingly, it can be found that light is barely absorbed. Therefore, the compound of Formula (II) may be used in the photoconductor of the electrophotographic image forming apparatus using the short-wavelength light source according to the above exemplary embodiment.
Photoconductors of electrophotographic image forming apparatuses are usually divided into laminated-type photoconductors and single-layer type photoconductors. Laminated-type photoconductors include two layers, formed of a charge generating layer including a binder resin and a charge generating material (CGM), and a charge transporting layer including a binder resin and a charge transporting material (mainly, hole transporting material (HTM)). In general, laminated-type photoconductors are used to prepare negative photoconductors.
Single-layer type photoconductors include all the binder resin, CGM, HTM, and an electron transporting material (ETM) within a same layer, and are generally used to prepare positive organic photoconductors.
The compound of Formula (I) according to the exemplary embodiment of the present general inventive concept may be used in either or both of the laminated-type photoconductor and the single-layer type photoconductor.
The compound of Formula (I) above may be used as the ETM in the photoconductor. In other words, the compound of Formula (I) may be included in the charge transporting layer of the laminated-type photoconductor, and may be included together with the CGM within the single layer of the single-layer type photoconductor.
Examples of the ETM, which may be used together with the compound of Formula (I) above may include an electron accepting low-molecular weight compound, such as benzoquinones, cyanoethylenes, cyanoquinodimethanes, fluorenones, xanthones, phenanthraquinones, phthalic acid anhydrides, thiopyrans and diphenoquinones, but are not limited thereto. Additionally, an electron transporting polymer or a pigment with n-type semiconductor characteristics may be used.
The photoconductive layer contained in the above described photoconductor includes the CGM and HTM.
Examples of the CGM may include an organic material such as a phthalocyanine-based pigment, an azo-based pigment, a quinone-based pigment, a perylene-based pigment, an indigo-based pigment, a bisbenzoimidazole-based pigment, a quinacridone-based pigment, an azulenium-based dye, a squarylium-based dye, a pyrylium-based dye, a triarylmethane-based dye, a cyanine-based dye, or the like; and an inorganic material such as amorphous silicon, amorphous selenium, trigonal selenium, tellurium, a selenium-tellurium alloy, cadmium sulfide, antimony sulfide, zinc sulfide, or the like. The CGM used in the photoconductive layer is limited to the above materials, and can be used alone or in combination of two or more.
The CGM may be titanyl oxyphthalocyanine, as represented by the following Formula (IX),
Examples of the HTM may include a nitrogen-containing cyclic compound or a condensed polycyclic compound, such as pyrenes, carbazoles, hydrazones, oxazoles, oxadiazoles, pyrazolines, arylamines, arylmethanes, benzidines, thiazoles, styryls, or the like; and a polymer or a polysilane-based compound having the above substituents in a main chain or a side chain.
The HTM may be a compound represented by the following Formula (X),
in which, R1, R2, R3, and R4 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C6 to C30 aryl group, and a substituted or unsubstituted C7 to C30 aralkyl group.
It is desirable that the HTM be a compound represented by the following Formula (Xl) taken from Formula (X),
The compound of Formula (XI) has an absorbance which is reduced to very close to 0 from approximately 400 nm in the wavelength of the light emitted from the light source, and accordingly, it can be found that light is barely absorbed. Therefore, the compound of Formula (XI) may be used in the photoconductor of the electrophotographic image forming apparatus using the short-wavelength light source according to the exemplary embodiment of the present general inventive concept.
Additionally, the HTM may be a compound represented by the following Formula (XII),
in which, R1, R2, R3, and R4 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C20 cycloalkyl group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C6 to C30 aryl group, and a substituted or unsubstituted C7 to C30 aralkyl group.
It is desirable that the HTM be a compound represented by the following Formula (XIII) taken from Formula (XII),
The compound of Formula (XIII) has an absorbance which is reduced to very close to 0 from approximately 350 nm in the wavelength of the light emitted from the light source, and accordingly, it can be found that light is barely absorbed. Therefore, the compound of Formula (XIII) may be used in the photoconductor of an electrophotographic image forming apparatus using the short-wavelength light source according to the exemplary embodiment of the present general inventive concept.
Additionally, according to another exemplary embodiment of the present general inventive concept, an electrophotographic image forming apparatus uses a short-wavelength light source and employs a photoconductor. The photoconductor includes a supporter, and a photoconductive layer which is formed on the supporter. The photoconductive layer may include a naphthalenetetracarboxylic acid diimide derivative represented by the following Formula (I),
in which, R1, R2, and R3 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C6 to C30 aryl group, and a substituted or unsubstituted C7 to C30 aralkyl group.
In the electrophotographic image forming apparatus using the compound of Formula (I) as a photoconductive layer, the light emitted from the light source of a laser scanning device may have a wavelength of approximately 400 nm to approximately 500 nm taking into consideration a resolution.
The compound of Formula (II) has an absorbance which is approximately 0.6 in a range of 350 nm to 400 nm, but is reduced to very close to 0 from approximately 400 nm, in the wavelength of the light emitted from the light source, and accordingly, it can be found that light is barely absorbed. Therefore, the compound of Formula (II) exhibiting the above absorbance level may be used in the photoconductor which can be exposed to the light emitted from the short-wavelength light source. Thus, a high-resolution image can be formed.
Additionally, in
The compounds represented by the above Formulae (i) and (ii) exhibit an absorbance which is higher than 0 at a wavelength of approximately 400 nm or higher. Therefore, it will be difficult to form a high-resolution image, because the above compounds exhibit high absorbance in the short-wavelength light source having a wavelength of approximately 400 nm to approximately 500 nm, to absorb light.
The above compounds of Formulae (i) and (ii) are used in Comparative Examples which are compared to the following Examples.
Hereinafter, in Examples 1 and 2, photoconductors of an electrophotographic image forming apparatus according to exemplary embodiments of the present general inventive concept, were prepared using a photoconductive layer including a compound represented by Formula (I). In Comparative Examples 1 and 2, photoconductors were prepared using compounds represented by Formulae (i) and (ii), which are conventional electron transporting materials (ETMs), instead of the compound represented by Formula (I).
A compound represented by Formula (II) (ETM, 26 parts by weight), a compound represented by Formula (IX) (y type titanyl oxyphthalocyanine, charge generating material (CGM), 3 parts by weight), a compound represented by Formula (XIII) (hole transporting material (HTM), 26 parts by weight), a compound represented by Formula (XIV) (binder resin, 45 parts by weight), and methylene chloride (420 parts by weight) and 1,1,2-trichloroethane (105 parts by weight) as a solvent, were sand-milled for 2 hours, and then dispersed using ultrasonic waves. The obtained solution was coated on an anodized aluminum drum as a supporter, and then dried at 110° C. for 1 hour to obtain a photoconductive drum having a thickness of approximately 15 mm to approximately 16 mm. Formula (XIV) is as follows,
A photoconductive drum was prepared in the same manner as in Example 1, except that the compound represented by Formula (XI) was used as the HTM.
A photoconductive drum was prepared in the same manner as in Example 1, except that the compound represented by Formula (i) was used as the ETM. Formula (i) is given by,
A photoconductive drum was prepared in the same manner as in Example 1, except that the compound represented by Formula (ii) was used as the ETM. Formula (ii) is given by,
Electrophotographic characteristics of each photoconductor obtained in Examples and Comparative Examples were measured using a drum photoconductor evaluation apparatus (Cynthia—92KSS).
Measurement was performed in the following conditions: a light source adopted a light emitting diode (LED) with a wavelength of 430 nm. A voltage was supplied so that a charge potential Vo was 600V, a surface potential value after exposure was recorded, and a relationship between energy and the surface potential was measured.
As illustrated in Table 1, the photoconductors of Examples 1 and 2 had low E1/2, E100, and E200 values compared to the photoconductors of Comparative Examples 1 and 2.
This is because the compound of Formula (II) in Examples 1 and 2 had a low absorbance, and the light of 430 nm freely reached the CGM to generate an electric charge effectively. Accordingly, the sensitivity was increased, and the E100 and E200 values were reduced.
In Comparative Examples 1 and 2, it is assumed that since the compounds of Formulae (i) and (ii) had very high absorbance (referring to
As described above, according to exemplary embodiments of the present general inventive concept, a photoconductor is prepared using a compound exhibiting a relatively low absorbance of a short-wavelength light in a predetermined waveband, and can be effectively used in an electrophotographic image forming apparatus using the light emitted from the short-wavelength light source.
Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-94558 | Sep 2006 | KR | national |
