Electrophotosensitive material Number:7,101,647 from the United States Patent and Trademark Office (PTO) owispatent The present invention provides an electrophotosensitive material which realizes uniform dispersion of phthalocyanines in a photosensitive layer and has high sensitivity to a digital light source, and also excellent in charge stability under the high temperature atmosphere, weatherability and NOx resistance. The electrophotosensitive material is produced by forming a single-layer type or multi-layer type photosensitive layer containing phthalocyanine as an electric charge generating material, an electric charge transferring material, a predetermined insoluble azo pigment and a predetermined binder resin on a conductive substrate and using, as the insoluble azo pigment, an insoluble azo pigment having no OH group in the molecule wherein (i) an absorbance in an absorption wavelength range of phthalocyanine is 1/3 or less of an absorbance of the phthalocyanine in the wavelength range, or (ii) an absorbance in a wavelength range of an exposure light source of an image forming apparatus is 1/3 or less of an absorbance of the phthalocyanine in the wavelength range.<H Electrophotosensitive, material, Electrophotosen, 7101647.html, Patent, pto, 7101647

Title: Electrophotosensitive material

Abstract: The present invention provides an electrophotosensitive material which realizes uniform dispersion of phthalocyanines in a photosensitive layer and has high sensitivity to a digital light source, and also excellent in charge stability under the high temperature atmosphere, weatherability and NOx resistance. The electrophotosensitive material is produced by forming a single-layer type or multi-layer type photosensitive layer containing phthalocyanine as an electric charge generating material, an electric charge transferring material, a predetermined insoluble azo pigment and a predetermined binder resin on a conductive substrate and using, as the insoluble azo pigment, an insoluble azo pigment having no OH group in the molecule wherein (i) an absorbance in an absorption wavelength range of phthalocyanine is 1/3 or less of an absorbance of the phthalocyanine in the wavelength range, or (ii) an absorbance in a wavelength range of an exposure light source of an image forming apparatus is 1/3 or less of an absorbance of the phthalocyanine in the wavelength range.

Patent Number: 7,101,647 Issued on 09/05/2006 to Azuma, et al.

Inventors: Azuma; Jun (Osaka, JP), Hamasaki; Kazunari (Osaka, JP), Kuboshima; Daisuke (Osaka, JP), Honma; Hisakazu (Osaka, JP)
Assignee: Kyocera Mita Corporation (Osaka, JP)

Appl. No.: 10/667,905

Filed: September 23, 2003

Foreign Application Priority Data


Sep 24, 2002 [JP]			2002-277778

Current U.S. Class: 430/56 ; 430/133; 430/78

Current International Class: G03G 5/06 (20060101)

Field of Search: 430/56,78,133

References Cited [Referenced By]

U.S. Patent Documents


5077161	December 1991	Law
5087540	February 1992	Murakami et al.
5190839	March 1993	Fujimaki et al.
5328788	July 1994	Omote et al.
5576131	November 1996	Takai et al.
5656407	August 1997	Kawahara
5858594	January 1999	Notsu et al.
6465143	October 2002	Tanaka et al.
2004/0214101	October 2004	Suzuki

Foreign Patent Documents


1 376 343	Dec., 1974	GB
03033858	Feb., 1991	JP
03037663	Feb., 1991	JP
07-175241	Jul., 1995	JP
07-199493	Aug., 1995	JP
09-034148	Feb., 1997	JP
2000-047406	Feb., 2000	JP
2000-047407	Feb., 2000	JP
2000-147809	May., 2000	JP
2000-147810	May., 2000	JP
2000-239553	Sep., 2000	JP
2000-242011	Sep., 2000	JP
2001-123087	May., 2001	JP
2002-055470	Feb., 2002	JP

Other References

Patent Abstract of Japan, vol. 015, No. 176, Publication No. 03037663, Publication Date: Feb. 19, 1991. cited by other.

Primary Examiner: Rodee; Christopher
Attorney, Agent or Firm: Smith, Gambrell & Russell, LLP

Claims

We claim:

1. A single-layer type electrophotosensitive material comprising a conductive substrate and a photosensitive layer containing an electric charge generating material, an electron transferring material and a hole transferring material as electric charge transferring materials, an insoluble azo pigment and a binder resin provided on the conductive substrate, wherein the electric charge generating material is phthalocyanine and the insoluble azo pigment has no OH group in the molecule, and an absorbance of the insoluble azo pigment in an absorption wavelength range of the electric charge generating material is 1/3 or less of an absorbance in the wavelength of the electric charge generating material, the phthalocyanine and the insoluble azo pigment being disposed together in the photosensitive layer; wherein the electron transferring material is incorporated in the amount within a range of from 5 to 200 parts by weight based on 100 parts by weight of the binder resin, and the hole transferring material is incorporated in the amount within a range of from 5 to 500 parts by weight based on 100 parts by weight of the binder resin; further wherein the insoluble azo pigment is a monoazo pigment represented by the general formula (1): ##STR00025## in the formula (1), X.sup.1 to X.sup.3 are the same or different and represent a nitro group, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, a group: --CONHR.sup.6, or a group: --SO.sup.2NHPh, R.sup.1 to R.sup.5 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.2 and R.sup.3 may be combined with each other to form an ureylene group, R.sup.6 and R.sup.7 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, and Ph represents a phenyl group; a disazo pigment represented by the general formula (2): ##STR00026## in the formula (2), X.sup.11 represents the general formula (22): ##STR00027## in the formula (22), X.sup.16 to X.sup.19 are the same or different and represent a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, R.sup.11 to R.sup.20 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.12 and R.sup.13 and/or R.sup.17 and R.sup.18 may be combined with each other to form an ureylene group, and R.sup.7 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group; a disazo pigment represented by the general formula (3): ##STR00028## in the formula (3), X.sup.21 represents the general formula (31) or the general formula (32): ##STR00029## in the formula (31), X.sup.22 to X.sup.25 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms and, in the formula (32), X.sup.26 and X.sup.27 are the same or different and represent a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, R.sup.21 to R.sup.30 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.22 and R.sup.23 and/or R.sup.27 and R.sup.28 may be combined with each other to form an ureylene group, and R.sup.7 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group; a disazo pigment represented by the general formula (4): ##STR00030## in the formula (4), X.sup.31 represents the general formula (41) or the general formula (42): ##STR00031## in the formula (41), X.sup.32 to X.sup.35 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms and, in the formula (42), X.sup.36 and X.sup.37 are the same or different and represent a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, R.sup.31 to R.sup.40 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.32 and R.sup.33 and/or R.sup.37 and R.sup.38 may be combined with each other to form an ureylene group, and R.sup.7 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a phenyl group; a disazo condensed pigment represented by the general formula (5): ##STR00032## in the formula (5), X.sup.41 represents the general formula (51): ##STR00033## in the formula (51), X.sup.42 and X.sup.43 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, R.sup.41 to R.sup.50 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.42 and R.sup.43 and/or R.sup.47 and R.sup.48 may be combined with each other to form an ureylene group, and R.sup.7 is as defined above; or a disazo condensed pigment represented by the general formula (6): ##STR00034## in the formula (6), X.sup.51 represents the formula (61): ##STR00035## in the formula (61), X.sup.52 to X.sup.55 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, R.sup.51 to R.sup.60 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.52 and R.sup.53 and/or R.sup.57 and R.sup.58 may be combined with each other to form an ureylene group, and R.sup.7 as defined above.

2. The electrophotosensitive material according to claim 1, wherein the binder resin is at least one resin selected from the group consisting of polycarbonate, polyester, polyarylate, polystyrene and polymethacrylate ester.

3. The electrophotosensitive material according to claim 1, wherein the phthalocyanine is .alpha. type titanyl phthalocyanine having each main diffraction peak at a Bragg angle (2.theta..+-.0.2.degree.)=7.6.degree. and 28.6.degree. in an X-ray diffraction spectrum, or Y type titanyl phthalocyanine having a main diffraction peak at a Bragg angle (2.theta..+-.0.2.degree.)=27.2.

4. The electrophotosensitive material according to claim 1, wherein the phthalocyanine is titanyl phthalocyanine and does not have an endothermic peak except for a peak associated with evaporation of adsorbed water in differential scanning calorimetry during heating from 50.degree.C. to 400.degree.C.

5. The electrophotosensitive material according to claim 1, wherein the photosensitive layer is obtained by forming a film using a coating solution containing the electric charge generating material, the electric charge transferring materials, the insoluble azo pigment and the binder resin to form a film, and a dispersion medium of the coating solution is at least one organic solvent selected from the group consisting of tetrahydrofuran, dioxane, dioxolane, cyclohexanone, toluene, xylene, dichloromethane, dichloroethane and chlorobenzene.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an electrophotosensitive material and, more particularly, to a digital electrophotosensitive material which is used in image forming apparatuses such as electrophotographic copying machine, facsimile and laser beam printer.

In image forming apparatuses such as electrophotographic copying machine, facsimile and laser beam printer, various organic photosensitive materials having the sensitivity in a wavelength range of a light source used in said apparatuses. Although a digital technique has recently been introduced into image forming apparatus, a red semiconductor laser (LD) and a light emitting diode (LED) are mainly used as the light source for digital image forming apparatus and light having a long wavelength of about 600 to 830 nm (orange light, red light and light in a near infrared range) are emitted from the light source and, therefore, it is strongly required to develop an organic photosensitive material which is excellent in sensitivity in these wavelength ranges.

Intense interest has been shown towards phthalocyanines (TiOPc) as an electric charge generating material having high sensitivity in a near infrared range. Particularly, a multi-layer type electrophotosensitive material using .alpha. type or Y type titanyl phthalocyanine (.alpha.-TiOPc, Y-TiOPc) or a mixed crystal of TiOPc and hydroxy metal phthalocyanine as an electric charge generating material has already been put into practical use.

On the other hand, a single-layer type electrophotosensitive material containing an electric charge generating material and an electric charge transferring material in a single photosensitive layer has the following advantages. That is, the single-layer type electrophotosensitive material is excellent in productivity because of its simple layer construction, as compared with a multi-layer type electrophotosensitive material comprising a conductive substrate and an electric charge generating layer and an electric charge transferring layer formed separately on the conductive substrate, and can inhibit the occurrence of layer defects during the formation of the photosensitive layer, and also the single-layer type electrophotosensitive material has improved optical characteristics because of less interface between layers and can be used as both of positive and negative charging type electrophotosensitive materials.

Therefore, there have been made various studies on the single-layer type electrophotosensitive material using the above-mentioned phthalocyanines as the electric charge generating material. However, there arises a problem that a single-layer type electrophotosensitive material having high sensitivity can not be obtained when using .alpha.-TiOPc, Y-TiOPc or a mixed crystal of TiOPc and hydroxymetal phthalocyanine as the electric charge generating material.

The reason is as follows. That is, a binder resin such as polycarbonate, polyarylate, polyester, polystyrene or polymethacrylate ester used in the formation of the photosensitive layer has low affinity with TiOPc or the mixed crystal and a dispersion medium of a coating solution for formation of a photosensitive layer is limited to a non-alcoholic solvent such as tetrahydrofuran, dioxane, dioxolane, toluene or methylene chloride taking account of the solubility of various materials constituting the photosensitive layer and, furthermore, the non-alcoholic solvent is a poor solvent to TiOPc or the mixed crystal.

Also there arises a problem that it becomes difficult to form a uniform photosensitive layer as a result of the occurrence of coagulative precipitation of TiOPc because of low dispersibility in the dispersion medium, and that the crystal form of TiOPc is transferred to a crystal form which is different from an expected crystal form after preparation of a dispersion because of low stability with a lapse of time in the dispersion medium.

Patent Documents 1 to 5 describe a coating solution prepared by incorporating TiOPc and specific azo pigments taking account of the dispersibility of a TiOPc-containing coating solution for formation of a photosensitive layer, and a single-layer type electrophotosensitive material (or photoconductor) using the same. Also Patent Documents 6 to 11 describe a single-layer type electrophotosensitive material comprising TiOPc and specific azo pigments.

However, the coating solution described in Patent Documents 1 to 5 still has a problem that the coating solution has poor storage stability. Furthermore, the electrophotosensitive material (photoconductor) described in Patent Documents 1 to 11 has a problem that it is inferior in charge stability and NOx resistance and such a problem drastically occurred under the high temperature atmosphere.

Patent Document 1: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2000-47406 (see claims 1 and 2 and paragraph numbers [0013] to [0030])

Patent Document 2: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2000-47407 (see claims 1 and 2 and paragraph numbers [0013] to [0029])

Patent Document 3: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2000-147810 (see claims 1 and 2 and paragraph numbers [0021] to [0036])

Patent Document 4: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2001-123087 (see claim 5 and paragraph numbers [0013] to [0026] and [0031])

Patent Document 5: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2000-239553 (see claim 1 and paragraph numbers [0014] to [0027])

Patent Document 6: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho Hei) No. 7-175241 (see claim 1 and paragraph number [0004])

Patent Document 7: Japanese Published Unexamined Patent application (Kokai Tokkyo Koho Hei) No. 9-34148 (see claim 1 and paragraph number [0004])

Patent Document 8: Japanese Published Unexamined Patent application (Kokai Tokkyo Koho) No. 2000-147809 (see claim 2 and paragraph numbers [0020] to [0035])

Patent Document 9: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2000-242011 (see claim 2 and paragraph numbers [0021] to [0040])

Patent Document 10: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2002-55470 (see claims 1 and 2 and paragraph numbers [0022] to [0036])

Patent Document 11: Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho Hei) No. 7-199493 (see claim 1 and paragraph numbers [0028] to [0029])

Thus, it is required to obtain an electrophotosensitive material, which has high sensitivity to a digital light source and also has high performances, by preparing a coating solution for formation of a photosensitive layer, which is excellent in dispersibility of phthalocyanines, stability in a dispersed state and stability with a lapse of time, and using the coating solution.

An object of the present invention is to provide an electrophotosensitive material which realizes uniform dispersion of phthalocyanines in a photosensitive layer and has high sensitivity to a digital light source, and also excellent in charge stability under the high temperature atmosphere, weatherability and NOx resistance, and preferably a single-layer type electrophotosensitive material.

Any azo pigments used in the inventions described in Patent Documents 1 to 11 are selected on the assumption that they exhibit the sensitivity in a broad visible range. Although a coupler residue including the naphthol structure portion is used in the azo pigments, the coagulability of the azo pigment itself is enhanced by the presence of an OH group having high polarity and also coagulative precipitation of the pigment occurs with a lapse of time in the coating solution for formation of a photosensitive layer because of low affinity with a binder resin such as polycarbonate.

Furthermore, it is considered that the OH group at the naphthol structure portion serves as an adsorption portion of an active gas such as NOx and, therefore, there arises a problem that an electrophotosensitive material containing the azo pigments is inferior in NOx resistance.

Since the azo pigments exhibit the sensitivity in a broad visible range, not only TiOPc incorporated as the electric charge generating material in the photosensitive layer, but also the azo pigments exhibit electric charge generating ability. However, since both of TiOPc and the azo pigments exhibit the electric charge generating ability, heat carrier is liable to occur and electric charge retention tends to be lowered. This leads to deterioration of the charge stability under the high temperature atmosphere.

Therefore, the present inventors have employed phthalocyanines having excellent sensitivity in a near infrared range during intensive study to achieve the above-mentioned object, and have studied intensively with a policy of incorporation of azo pigments in a single-layer or multi-layer type photosensitive layer for the purpose of improving the dispersibility of the coating solution for formation of a photosensitive layer.

As a result, they have found a new fact that there can be provided an electrophotosensitive material which realizes uniform dispersion of phthalocyanines in a photosensitive layer and has high sensitivity to a digital light source, and also excellent in charge stability under the high temperature atmosphere, weatherability and NOx resistance, and particularly a single-layer type electrophotosensitive material when using, as the azo pigments, (I) an insoluble azo pigment having no OH group such as hydroxyl group or carboxyl group wherein an absorbance in an absorption wavelength range of an electric charge generating material (phthalocyanine) is 1/3 or less of an absorbance in the wavelength of the electric charge generating material, or (II) an insoluble azo pigment having no OH group such as hydroxyl group or carboxyl group wherein an absorbance in a wavelength range of an exposure light source is 1/3 or less of an absorbance of the electric charge generating material (phthalocyanine) in the wavelength range in an image forming apparatus using the electrophotosensitive material of the present invention. Thus, the present invention has been completed.

SUMMARY OF THE INVENTION

To achieve the above-mentioned object, a first electrophotosensitive material of the present invention comprises a conductive substrate and a photosensitive layer containing an electric charge generating material, an electric charge transferring material, an insoluble azo pigment and a binder resin provided on the conductive substrate, wherein the electric charge generating material is phthalocyanine and the in soluble azo pigment has no OH group in the molecule, and an absorbance of the insoluble azo pigment in an absorption wavelength range of the electric charge generating material is 1/3 or less of an absorbance in the wavelength of the electric charge generating material.

The electrophotosensitive material of the present invention is characterized in that the binder resin is at least one resin selected from the group consisting of polycarbonate, polyester, polyallylate, polystyrene and polymethacrylate ester.

To achieve the above-mentioned object, a second electrophotosensitive material of the present invention comprises a conductive substrate and a photosensitive layer containing an electric charge generating material, an electric charge transferring material, an insoluble azo pigment and a binder resin provided on the conductive substrate, wherein the electric charge generating material is phthalocyanine and the insoluble azo pigment has no OH group in the molecule, and an absorbance of the insoluble azo pigment in a wavelength range of an exposure light source of an image forming apparatus is 1/3 or less of an absorbance in the wavelength of the electric charge generating material.

In the first and second electrophotosensitive materials, the binder resin is preferably at least one resin selected from the group consisting of polycarbonate, polyester, polyarylate, polystyrene and polymethacrylate ester.

According to the first and second electrophotosensitive materials, since electric charge generating materials such as phthalocyanine and a specific insoluble azo pigment are incorporated in the material constituting the photosensitive layer, the dispersibility of phthalocyanine in a coating solution for formation of a photosensitive layer can be enhanced and also uniform dispersion of phthalocyanine can be realized in the photosensitive layer formed by using the coating solution. These effects are particularly remarkable in case phthalocyanine is titanyl phthalocyanine.

Since the specific insoluble azo pigment does not have an OH group such as hydroxyl group or carboxyl group in the molecule and a polar portion capable of serving as an adsorption portion of an active gas such as NOx does not exist, NOx resistance and charge stability under the high temperature atmosphere of the electrophotosensitive material are not lowered even if the insoluble azo pigment is incorporated in the photosensitive layer.

As described above, the specific insoluble azo pigment is characterized in that: (i) an absorbance in an absorption wavelength range of an electric charge generating material (phthalocyanine) is low, for example, it is 1/3 or less of an absorbance of the phthalocyanine in the wavelength range, or (ii) an absorbance in a wavelength range of an exposure light source in an image forming apparatus is low, for example, it is 1/3 or less of an absorbance in the wavelength range.

In other words, since the specific insoluble azo pigment is inactive in a sensitivity range of phthalocyanine as the electric charge generating material and exerts less influence on electric charge generating ability, the charge stability of the electrophotosensitive material is not lowered. Such an effect is particularly remarkable under the high temperature atmosphere.

In the first and second electrophotosensitive materials of the present invention, the phthalocyanine as the electric charge generating material is preferably .alpha. type titanyl phthalocyanine having each main diffraction peak at a Bragg angle (2 .theta..+-.0.2.degree.)=7.6.degree. and 28.6.degree. in an X-ray diffraction spectrum, or Y type titanyl phthalocyanine having a main diffraction peak at a Bragg angle (2 .theta..+-.0.2.degree.)=27.2 in view of an improvement in sensitivity of the photosensitive material.

In the present invention, Cu--K.alpha. characteristic X-ray (wavelength: 1.54 .ANG.) was used in the analysis of an X-ray diffraction spectrum.

In the first and second electrophotosensitive materials of the present invention, the phthalocyanine as the electric charge generating material is preferably titanyl phthalocyanine and does not have an endothermic peak except for a peak associated with evaporation of adsorbed water in differential scanning calorimetry during heating from 50.degree. C. to 400.degree. C.

In the results of the measurement due to differential scanning calorimetry (DSC), no endothermic peak observed except for a peak associated with evaporation of adsorbed water within a range from 50.degree. C. to 400.degree. C. shows that the phthalocyanine hardly cause crystal transfer and is stable.

The phthalocyanine itself is excellent in dispersibility in the binder resin and storage stability and also further improves the dispersibility in the binder resin when incorporated in the photosensitive layer, together with the insoluble azo pigment.

In the first and second electrophotosensitive materials of the present invention, the photosensitive layer is preferably obtained by forming a film using a coating solution containing the electric charge generating material, the electric charge transferring material, the insoluble azo pigment and the binder resin, and the coating solution is preferably at least one organic solvent selected from the group consisting of tetrahydrofuran, dioxane, dioxolane, cyclohexanone, toluene, xylene, dichloromethane, dichloroethane and chlorobenzene.

By using the above-mentioned organic solvents as a dispersion medium of the coating solution for formation of a photosensitive layer, the dispersibility of the electric charge generating material (phthalocyanine) and the insoluble azo pigment in the coating solution, and the photosensitive layer formed by the coating solution can be improved.

In the first and second electrophotosensitive materials of the present invention, the insoluble azo pigment is preferably a mono azo pigment represented by the general formula (1):

##STR00001## in the formula (1), X.sup.1 to X.sup.3 are the same or different and represent a nitro group, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, a group: --CONHR.sup.6, or a group: --SO.sub.2NHPh, R.sup.1 to R.sup.5 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.2 and R.sup.3 may be combined with each other to form an ureylene group, R.sup.6 and R.sup.7 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group, and Ph represents a phenyl group; a disazo pigment represented by the general formula (2):

##STR00002## in the formula (2), X.sup.11 represents the general formula (21) or the general formula (22):

##STR00003## (in the formula (21), X.sup.12 to X.sup.15 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms and, in the formula (22), X.sup.16 to X.sup.9 are the same or different and represent a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms), R.sup.11 to R.sup.20 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.12 and R.sup.13 and/or R.sup.17 and R.sup.18 may be combined with each other to form an ureylene group, and R.sup.7represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group; a disazo pigment represented by the general formula (3):

##STR00004## in the formula (3), X.sup.21 represents the general formula (31) or the general formula (32):

##STR00005## (in the formula (31), X.sup.22 to X.sup.25 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms and, in the formula (32), X.sup.26 and X.sup.27 are the same or different and represent a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms), R.sup.21 to R.sup.30 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.22 and R.sup.23 and/or R.sup.27 and R.sup.28 may be combined with each other to form an ureylene group, and R.sup.7represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group;

a disazo pigment represented by the general formula (4):

##STR00006## in the formula (4), X.sup.31 represents the general formula (41) or the general formula (42):

##STR00007## (in the formula (41), X.sup.32 to X.sup.35 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms and, in the formula (42), X.sup.36 and X.sup.37 are the same or different and represent a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms), R.sup.31 to R.sup.40 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.32 and R.sup.33 and/or R.sup.37 and R.sup.38 may be combined with each other to form an ureylene group, and R.sup.7 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a phenyl group;

a disazo condensed pigment represented by the general formula (5):

##STR00008## in the formula (5), X.sup.41 represents the general formula (51):

##STR00009## (in the formula (51), X.sup.42 and X.sup.43 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms), R.sup.41 to R.sup.50 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.42 and R.sup.43 and/or R.sup.47 and R.sup.48 may be combined with each other to form an ureylene group, and R.sup.7 is as defined above; or

a disazo condensed pigment represented by the general formula (6):

##STR00010## in the formula (6), X.sup.51 represents the formula (61):

##STR00011## (in the formula (61), X.sup.52 to X.sup.55 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms), R.sup.51 to R.sup.60 are the same or different and represent a hydrogen atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an alkoxycarbonyl group having 1 to 2 carbon atoms, or a group: --NHCOR.sup.7, provided that R.sup.52 and R.sup.53 and/or R.sup.57 and R.sup.58 may be combined with each other to form an ureylene group, and R.sup.7 is as defined above.

The insoluble azo pigment has not an OH group such as hydroxyl group or carboxyl group in the molecule and also has no sensitivity in a near infrared range, or it is characterized in that: (i) an absorbance in an absorption wavelength range of an electric charge generating material (phthalocyanine) is low, for example, it is 1/3 or less of an absorbance of the phthalocyanine in the wavelength range, or (ii) an absorbance in a wavelength range of an exposure light source in an image forming apparatus is low, for example, it is 1/3 or less of an absorbance in the wavelength range of the electric charge generating material (phthalocyanine).

Therefore, the above-mentioned insoluble azo pigment is remarkably preferable in view of the achievement of an object of the present invention, which is to provide an electrophotosensitive material which realizes uniform dispersion of phthalocyanines in a photosensitive layer and has high sensitivity to a digital light source, and also excellent in charge stability under the high temperature atmosphere, weatherability and NOx resistance.

The first and second electrophotosensitive materials are preferably single-layer type electrophotosensitive materials comprising a conductive substrate and a single photosensitive layer containing an electric charge generating material, an electric charge transferring material, an insoluble azo pigment and a binder resin provided on the conductive substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing an X-ray diffraction spectrum of Y type TiOPc used in the Examples.

FIG. 2 is a graph showing the results of differential scanning calorimetry of Y type TiOPc used in the Examples.

FIG. 3 is a graph showing an X-ray diffraction spectrum of .alpha. type TiOPc used in Example 13.

DETAILED DESCRIPTION OF THE INVENTION

The electrophotosensitive material of the present invention will be described in detail.

[Electric Charge Generating Material]

In the electrophotosensitive material of the present invention, phthalocyanine is used as the electric charge generating material.

The phthalocyanine varies depending on the kind of coordination metal and, for example, metal-free phthalocyanine, titanyl phthalocyanine, copper phthalocyanine, aluminum chloro phthalocyanine, chloroindium phthalocyanine, magnesium phthalocyanine, zinc phthalocyanine, and vanadyl phthalocyanine are known. Individual phthalocyanine is further classified into several kinds according to its crystal form. As the phthalocyanine which can be used in the present invention, the kind and crystal form of the coordination metal are not specifically limited and conventionally known any phthalocyanines can be used. Among these phthalocyanines, titanyl phthalocyanine (TiOPc) having excellent sensitivity in a near infrared range is preferably used.

As TiOPc, for example, those having various crystal forms such as .alpha. type TiOPc, Y type TiOPc, .beta. type TiOPc and C type TiOPc are known. TiOPc, which can be used in the present invention, is not specifically limited and conventionally known TiOPc having various crystal forms can be used.

Among these, .alpha. type titanyl phthalocyanine having each main diffraction peak at a Bragg angle (2 .theta..+-.0.2.degree.)=7.6.degree. and 28.6.degree. in an X-ray diffraction spectrum, and Y type titanyl phthalocyanine having a main diffraction peak at a Bragg angle (2 .theta..+-.0.2.degree.)=27.2 are preferably used in the present invention because these titanyl phthalocyanines have extremely high sensitivity in a near infrared range and are advantageous to obtain a single-layer type electrophotosensitive material having high sensitivity.

Among preferable examples of TiOPc, Y type titanyl phthalocyanine having each main diffraction peak at a Bragg angle (2 .theta..+-.0.2.degree.)=27.2 has a problem such as poor stability in an organic solvent such as tetrahydrofuran contained in the coating solution for formation of a photosensitive layer.

Therefore, such phthalocyanine is preferably titanyl phthalocyanine which does not have an endothermic peak except for a peak associated with evaporation of adsorbed water in differential scanning calorimetry during heating from 50.degree. C. to 400.degree. C.

This titanyl phthalocyanine can be prepared by two methods (1) and (2) described below (see claims 5 and 6 and paragraph numbers [0029] to [0039] of Japanese Published Unexamined Patent Application (Kokai Tokkyo Koho) No. 2001-181531).

(1) A method comprising a pigmentation pretreatment step of adding a titanyl phthalocyanine in an aqueous organic solvent, stirring under heating for a fixed time, and allowing the resulting solution to stand for a fixed time under the conditions at a temperature lower than that of the above stirring process, thereby to stabilize the solution; and a pigmentation step of removing the aqueous organic solvent from the solution to obtain a crude crystal of the titanylphthalocyanine, dissolving the crude crystal of the titanyl phthalocyanine in a solvent, adding dropwise the solution in a poor solvent to recrystallize the titanyl phthalocyanine compound, and then subjecting the recrystallized compound to milling treatment in a non-aqueous solvent, with water contained therein.

(2) A method comprising a pigmentation pretreatment step of adding a titanyl phthalocyanine in an aqueous organic solvent, stirring under heating for a fixed time, and allowing the resulting solution to stand for a fixed time under the conditions at a temperature lower than that of the above stirring process, thereby to stabilize the solution; a step of removing the aqueous organic solvent from the solution to obtain a crude crystal of the titanyl phthalocyanine, and treating the crude crystal of the titanyl phthalocyanine according to acid-paste method; and a step of subjecting a low-crystalline titanyl phthalocyanine compound obtained by the above step to milling treatment, with water contained therein.

[Insoluble Azo Pigment]

The insoluble azo pigment used in the electrophotosensitive material of the present invention is characterized in that: (I) the insoluble azo pigment has no OH group such as hydroxyl group or carboxyl group wherein an absorbance in an absorption wavelength range of an electric charge generating material (phthalocyanine) is 1/3 or less of an absorbance in the wavelength of the electric charge generating material (that is, the insoluble azo pigment has no sensitivity in the absorption wavelength range of the electric charge generating material (phthalocyanine), or has very weak sensitivity), or (II) the insoluble azo pigment has no OH group such as hydroxyl group or carboxyl group wherein an absorbance in a wavelength range of an exposure light source is 1/3 or less of an absorbance of the electric charge generating material (phthalocyanine) in the wavelength range in an image forming apparatus using the electrophotosensitive material of the present invention (that is, the insoluble azo pigment has no sensitivity in the absorption wavelength range of the exposure light source, or has very weak sensitivity).

Even if such an insoluble azo pigment is used, it does not inhibit electric charge generating ability due to phthalocyanine and only exerts an effect of improving the dispersibility of phthalocyanine in a photosensitive layer or a coating solution for formation of the photosensitive layer.

Examples of the insoluble azo pigment, which satisfies the above-mentioned conditions, include mono azo pigment represented by the general formula (1), disazo pigments represented by the general formulas (2) to (4), and disazo condensed pigment represented by the general formula (5) or (6). These azo pigments may be incorporated alone in the photosensitive layer of the electrophotosensitive material of the present invention, or a mixture of two or more kinds of them may be incorporated therein. (Mono azo pigment represented by the general formula (1))

In the mono azo pigment represented by the general formula (1), X.sup.1 to X.sup.3 may be the same or different substituents.

Examples of the substituent corresponding to X.sup.1 to X.sup.3 include nitro group, chlorine atom, alkyl group having 1 to 3 carbon atoms (for example, methyl group, ethyl group, n-propyl group, or isopropyl group), perfluoroalkyl group having 1 to 3 carbon atoms (wherein all hydrogen atoms in the alkyl group are replaced by fluorine atoms), alkoxy group having 1 to 3 carbon atoms (for example, methoxy group, ethoxy group, n-propoxy group, or isopropoxy group), alkoxycarbonyl group having 1 to 2 carbon atoms (for example, methoxycarbonyl group or ethoxycarbonyl group), group: --CONHR.sup.6 (for example, carbamoyl group; R.sup.6 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group), and group: --SO.sub.2NHPh (for example, N-phenylsulfamoyl group).

In the mono azo pigment represented by the general formula (1), R.sup.1 to R.sup.5 may be the same or different substituents.

Examples of the substituent corresponding to R.sup.1 to R.sup.5 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), alkoxy group having 1 to 3 carbon atoms (supra), alkoxycarbonyl group having 1 to 2 carbon atoms (supra), and group: --NHCOR.sup.7 (for example, acetamide group or benzamide group; R.sup.7 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a phenyl group). On the basis of the carbon atom attached to the nitrogen atom of the benzene ring on which R.sup.1 to R.sup.5 are substituted, carbon atoms at the meta- and para-positions (for example, R.sup.2 and R.sup.3) may be combined with each other to form an ureylene group represented by the formula:

##STR00012##

Specific examples of the mono azo pigment represented by the general formula (1) are shown in Table 1, together with Color Index Number (C.I. No.).

TABLE-US-00001 TABLE 1 .asterisk-pseud.Monoazo pigment of the general formula (1) C.I. No. X.sup.1 X.sup.3 R.sup.1 R.sup.5 Pigment Yellow 1 2: --NO.sub.2, 4: --CH.sub.3 -- 2 2: --NO.sub.2, 4: --Cl R.sup.1, R.sup.3: --CH.sub.3 3 2: --NO.sub.2, 4: --Cl R.sup.1: --Cl 4 4: --NO.sub.2 -- 5 2: --NO.sub.2 -- 6 2: --NO.sub.2, 4: --Cl -- 9 2: --NO.sub.2, 4: --CH.sub.3 -- 49 2: --CH.sub.3, 4: --Cl R.sup.1, R.sup.4: --OCH.sub.3, R.sup.3: --Cl 65 2: --NO.sub.2, 4: --OCH.sub.3 R.sup.1: --OCH.sub.3 73 2: --NO.sub.2, 4: --Cl R.sup.1: --OCH.sub.3 74 2: --OCH.sub.3, 4: --NO.sub.2 R.sup.1: --OCH.sub.3 75 2: --NO.sub.2, 4: --Cl R.sup.3: --OC.sub.2H.sub.5 97 2, 5: --OCH.sub.3 R.sup.1, R.sup.4: --OCH.sub.3, R.sup.3: --Cl 4: --SO.sub.2NHPh 98 2: --NO.sub.2; 4: --Cl R.sup.1: --CH.sub.3, R.sup.3: --Cl 116 2: --Cl, 5: --CONH.sub.2 R.sup.4: --NHCOCH.sub.3 120 3, 5: --COOCH.sub.3 R.sup.2 R.sup.3: ureylene 154 2: --CF.sub.3 R.sup.2 R.sup.3: ureylene Pigment Orange 1 2: --NO.sub.2, 4: --OCH.sub.3 R.sup.1: --CH.sub.3 36 2: --NO.sub.2, 4: --Cl R.sup.2 R.sup.3: ureylene

In Table 1, abbreviations described in the respective columns "X.sup.1 X.sup.3" and "R.sup.1 R.sup.5" are as follows.

"--NO.sub.2" denotes a nitro group, "--Cl" denotes a chlorine atom, "--CH.sub.3" s a methyl group, "--CF.sub.3" denotes a perfluoromethyl group, "--OCH.sub.3" denotes a methoxy group, "--OC.sub.2H.sub.5" denotes an ethoxy group, "--COOCH.sub.3" denotes a methoxycarbonyl group, "--SO.sub.2NHPh" denotes an N-phenylsulfamoyl group, and "--CONH.sub.2" denotes a carbamoyl group, respectively.

"2:", "4:" and "5:" in the column "X.sup.1 X.sup.3" denote the positions of the substituent on the benzene ring, and respectively denote "2-position", "4-position" and "5-position" on the basis of the carbon atom attached to the nitrogen atom. "2,5:" and"3,5:" denote that two same groups are substituted on the benzene ring, and denote that the substitution positions are "2- and 5-positions" and "3- and 5-positions" on the basis of the carbon atom.

"R.sup.2 R.sup.3: ureylene" in the column "R.sup.1 R.sup.5" denotes that R.sup.2 and R.sup.3 are combined with each other to form an ureylene group. Among R.sup.1 to R.sup.5, non-described groups denote that a hydrogen atom is substituted and "--" denotes that any of R.sup.1 to R.sup.5 are hydrogen atoms.

(Disazo Pigment Represented by the General Formula (2))

In the disazo pigment represented by the general formula (2), either of divalent groups represented by the general formula (21) and the general formula (22) is selected as X.sup.11.

In the divalent group represented by the general formula (21), X.sup.12 to X.sup.15 may be the same or different substituents. Examples of the substituent corresponding to X.sup.12 to X.sup.15 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), and alkoxy group having 1 to 3 carbon atoms (supra).

In the divalent group represented by the general formula (22), X.sup.16 to X.sup.19maybe the same or different substituents. Examples of the substituent corresponding to X.sup.16 to X.sup.19 include chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), and alkoxy group having 1 to 3 carbon atoms (supra).

In the disazo pigment represented by the general formula (2), R.sup.11 to R.sup.20 maybe the same or different substituents. Examples of the substituent corresponding to R.sup.11 to R.sup.20 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), alkoxy group having 1 to 3 carbon atoms (supra), alkoxycarbonyl group having 1 to 2 carbon atoms (supra), and group: --NHCOR.sup.7 (supra). On the basis of the carbon atom attached to the nitrogen atom of the benzene ring on which R.sup.11 to R.sup.20 are substituted, carbon atoms at the meta- and para-positions (for example, R.sup.12 and R.sup.13, and R.sup.17 and R.sup.18) may be combined with each other to form an ureylene group.

Specific examples of the disazo pigment represented by the general formula (2) are shown in Tables 2 and 3, together with Color Index Number (C.I. No.).

TABLE-US-00002 TABLE 2 .asterisk-pseud.Disazo pigment of the general formula (2), X.sup.11: general formula (21) C.I. No. X.sup.12, X.sup.14 X.sup.13, X.sup.15 R.sup.11 R.sup.20 Pigment Yellow 12 --Cl --H -- 13 --Cl --H R.sup.11, R.sup.13 , R.sup.16, R.sup.18: --CH.sub.3 14 --Cl --H R.sup.11, R.sup.16: --CH.sub.3 15 --OCH.sub.3 --Cl R.sup.11, R.sup.13, R.sup.16, R.sup.18: --CH.sub.3 17 --Cl --H R.sup.11, R.sup.16: --OCH.sub.3 55 --Cl --H R.sup.13, R.sup.18: --CH.sub.3 81 --Cl --Cl R.sup.11, R.sup.13, R.sup.16, R.sup.18: --CH.sub.3 83 --Cl --H R.sup.11, R.sup.14, R.sup.16, R.sup.19: --OCH.sub.3 R.sup.13, R.sup.18: --Cl 87 --Cl --H R.sup.11, R.sup.14, R.sup.16, R.sup.19: --OCH.sub.3 113 --Cl --Cl R.sup.11, R.sup.16: --CH.sub.3 R.sup.13, R.sup.18: --Cl 170 --Cl --H R.sup.13, R.sup.18: --OCH.sub.3 171 --Cl --H R.sup.11, R.sup.16: --CH.sub.3 R.sup.13, R.sup.18: --Cl 172 --Cl --H R.sup.11, R.sup.16: --OCH.sub.3 R.sup.14, R.sup.19: --Cl Pigment Orange 16 --OCH.sub.3 --H --

TABLE-US-00003 TABLE 3 .asterisk-pseud.Disazo pigment of the general formula (2), X.sup.11: general formula (22) C.I. No. X.sup.16, X.sup.17 X.sup.18, X.sup.19 R.sup.11 R.sup.20 Pigment Yellow 180 -- -- R.sup.12 R.sup.13, R.sup.17 R.sup.18: ureylene

In Tables 2 and 3, among abbreviations described in the respective columns "X.sup.12, X.sup.14", "X.sup.13, X.sup.15" and "R.sup.11--R.sup.20", "--Cl" and "--OCH.sub.3" are as defined in Table 1. "--H" denotes a hydrogen atom. "--" in the column "X.sup.13, X.sup.15" denotes that a corresponding group is absent. "R.sup.12 R.sup.13, R.sup.17 R.sup.18: ureylene" in the column R.sup.11 R.sup.20" denotes that R.sup.12 and R.sup.13 and R.sup.17 and R.sup.18 are combined with each other to form an ureylene group. Among R.sup.11 to R.sup.20, non-described groups denote that a hydrogen atom is substituted and "--" denotes that any of R.sup.11 to R.sup.20 are hydrogen atoms.

(Disazo Pigment Represented by the General Formula (3))

In the disazo pigment represented by the general formula (3), either of divalent groups represented by the general formula (31) and the general formula (32) is selected as X.sup.21.

In the divalent group represented by the general formula (31), X.sup.22 to X.sup.25 maybe the same or different substituent. Examples of the substituent corresponding to X.sup.22 to X.sup.24 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), and alkoxy group having 1 to 3 carbon atoms (supra).

In the divalent group represented by the general formula (32), X.sup.26and X.sup.27 maybe the same or different substituents. Examples of the substituent corresponding to X.sup.26 and X.sup.27 include chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), and alkoxy group having 1 to 3 carbon atoms (supra).

In the disazo pigment represented by the general formula (3), R.sup.21 to R.sup.30 maybe the same or different substituents. Examples of the substituent corresponding to R.sup.21 to R.sup.30 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), alkoxy group having 1 to 3 carbon atoms (supra), alkoxycarbonyl group having 1 to 2 carbon atoms (supra), and group: --NHCOR.sup.7 (supra) On the basis of the carbon atom attached to the nitrogen atom of the benzene ring on which R.sup.21 to R.sup.30 are substituted, carbon atoms at the meta- and para-positions (for example, R.sup.22 and R.sup.23, and R.sup.27 and R.sup.28) may be combined with each other to form an ureylene group.

Specific examples of the disazo pigment represented by the general formula (3) are shown in Table 4, together with Color Index Number (C.I. No.).

TABLE-US-00004 TABLE 4 .asterisk-pseud.Disazo pigment of the general formula (3), X.sup.21: general formula (31) C.I. No. X.sup.22, X.sup.24 X.sup.23, X.sup.25 R.sup.21 R.sup.30 Pigment Yellow 16 --CH.sub.3 --H R.sup.21, R.sup.23, R.sup.26, R.sup.28: --Cl 77 --CH.sub.3 --H R.sup.21, R.sup.26: --CH.sub.3 R.sup.24, R.sup.29: --Cl

In Table 4, among abbreviations described in the respective columns "X.sup.22, X.sup.24", "X.sup.23, X.sup.25" and "R.sup.21 R.sup.30", any of "--H", "--Cl" and "--CH.sub.3" are as defined in Tables 1 to 3. Among R.sup.21 to R.sup.30, groups which are not described in the column "R.sup.21--R.sup.30" denote that a hydrogen atom is substituted.

(Disazo Pigment Represented by the General Formula (4))

In the disazo pigment represented by the general formula (4), either of divalent groups represented by the general formula (41) and the general formula (42) is selected as X.sup.31.

In the divalent group represented by the general formula (41), X.sup.32 to X.sup.35maybe the same or different substituents. Examples of the substituent corresponding to X.sup.32 to X.sup.35 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), and alkoxy group having 1 to 3 carbon atoms (supra).

In the divalent group represented by the general formula (42), X.sup.36 and X.sup.37 maybe the same or different substituents. Examples of the substituent corresponding to X.sup.36 and X.sup.37 include chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), and alkoxy group having 1 to 3 carbon atoms (supra).

In the disazo pigment represented by the general formula (4), R.sup.31 to R.sup.40 maybe the same or different substituents. Examples of the substituent corresponding to R.sup.31 to R.sup.40 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), alkoxy group having 1 to 3 carbon atoms (supra), alkoxycarbonyl group having 1 to 2 carbon atoms (supra), and group: --NHCOR.sup.7 (supra). On the basis of the carbon atom attached to the nitrogen atom of the benzene ring on which R.sup.21 to R.sup.30 are substituted, carbon atoms at the meta- and para-positions (for example, R.sup.32 and R.sup.33, and R.sup.37 and R.sup.38) may be combined with each other to form an ureylene group.

Specific examples of the disazo pigment represented by the general formula (4) are shown in Table 5, together with Color Index Number (C.I. No.).

TABLE-US-00005 TABLE 5 .asterisk-pseud.Disazo pigment of the general formula (4), X.sup.31: general formula (42) C.I. No. X.sup.36 X.sup.37 R.sup.31 R.sup.40 Pigment Yellow 155 -- -- R.sup.31, R.sup.34, R.sup.36, R.sup.39: --COOCH.sub.3

In Table 5, among abbreviations described in the respective columns "X.sup.36", "X.sup.37" and "R.sup.31 R.sup.40", any of "CH.sub.3OCO" and "--" are as defined in Tables 1 to 4. Among R.sup.31 to R.sup.40, groups which are not described in the column "R.sup.31 R.sup.40" denote that a hydrogen atom is substituted.

(Disazo Condensed Pigment Represented by the General Formula (5))

In the disazo condensed pigment represented by the general formula (5), X.sup.41 corresponds to a divalent group represented by the general formula (51).

In the divalent group represented by the general formula (51), X.sup.42 and X.sup.43 maybe the same or different substituents. Examples of the substituent corresponding to X.sup.42 and X.sup.43 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), and alkoxy group having 1 to 3 carbon atoms (supra).

In the disazo condensed pigment represented by the general formula (5), R.sup.41 to R.sup.50 may be the same or different substituents. Examples of the substituent corresponding to R.sup.41 to R.sup.50 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (supra), perfluoroalkyl group having 1 to 3 carbon atoms (supra), alkoxy group having 1 to 3 carbon atoms (supra), alkoxycarbonyl group having 1 to 2 carbon atoms (supra), and group: --NHCOR.sup.7 (supra). On the basis of the carbon atom attached to the nitrogen atom of the benzene ring on which R.sup.41 to R.sup.50 are substituted, carbon atoms at the meta- and para-positions (for example, R.sup.42 and R.sup.43, and R.sup.47 and R.sup.48) may be combined with each other to form an ureylene group.

Specific examples of the disazo pigment represented by the general formula (5) are shown in Table 6, together with Color Index Number (C.I. No.).

TABLE-US-00006 TABLE 6 .asterisk-pseud. Disazo condensed pigment of the general formula (5) C. I. No. X.sup.42 X.sup.43 R.sup.41 R.sup.50 Pigment Yellow 93 Cl Cl R.sup.41, R.sup.46: --CH.sub.3, R.sup.42, R.sup.47: --Cl 94 Cl Cl R.sup.41, R.sup.46: --CH.sub.3, R.sup.44, R.sup.49: --Cl 95 CH.sub.3 CH.sub.3 R.sup.41, R.sup.46: --CH.sub.3, R.sup.44, R.sup.49: --Cl

In Table 6, among abbreviations described in the respective columns "X.sup.42", "X.sup.43" and "R.sup.41 R.sup.50", any of "--Cl" and "--CH.sub.3" are as defined in Tables 1 to 5. Among R.sup.41 to R.sup.50, groups which are not described in the column "R.sup.41 R.sup.50" denote that a hydrogen atom is substituted.

(Disazo Condensed Pigment Represented by the General Formula (6))

In the disazo condensed pigment represented by the general formula (6), X.sup.51 corresponds to a divalent group represented by the general formula (61).

In the divalent group represented by the general formula (61), X.sup.52 to X.sup.55 maybe the same or different substituents. Examples of the substituent corresponding to X.sup.52 to X.sup.55 include hydrogen atom, chlorine atom, alkyl group having 1 to 3 carbon atoms (s