JPH07271065A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] An electrophotographic offset that improves the sensitizing property of a sensitizing dye used in an electrophotographic photosensitive member composed of an inorganic photoconductive photosensitive member and is less likely to cause printing stains. Serve the master. In an electrophotographic photoreceptor having a photoconductor layer containing an inorganic photoconductor, a binder resin, a sensitizing dye and optionally a sensitization aid on a conductive support, the electrophotographic photoreceptor is shown below. It is characterized by containing at least one kind of compound described above. In the formula, R ¹ represents an alkyl group, an alkoxy group or the like, and Z ¹
Represents a group of atoms necessary for forming a hydrocarbon ring by combining with an aromatic ring when present. l, m, and n are integers of 0 to 3, k is an integer of 1 to 2, and M is a hydrogen atom, an alkali metal salt, or an organic ammonium salt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in sensitizing property of a sensitizing dye used in an electrophotographic photosensitive member composed of an inorganic photoconductive photosensitive member. The present invention also relates to improvement of an electrophotographic lithographic printing plate precursor that is used by desensitizing an electrophotographic photosensitive member composed of an inorganic photoconductive photosensitive member by etching treatment, and more specifically to improvement of printing stains.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member having a photoconductive layer containing a photoconductive zinc oxide, a binder resin, a sensitizing dye and a sensitization aid on a conductive support has been known. There is. Zinc oxide has been used in large amounts as a photoreceptor for electrophotography because it is inexpensive, easy to handle, and pollution-free.

The photosensitive wavelength range peculiar to zinc oxide is ultraviolet (38
0 nm), and in order to have sensitivity in the visible light region when used as an electrophotographic photoreceptor, dyes such as rose bengal, erythrosine, fluorescein, methylene blue, crystal violet, and bromphenol blue are used as sensitizing dyes. In addition, it is used after spectral sensitization. The zinc oxide electrophotographic photoreceptor using such a sensitizing dye is used as a camera exposure type offset master for direct plate making by a light source such as a halogen lamp because it has sensitivity in the visible light region.

Among sensitizing dyes used to have sensitivity in the visible light region, rose bengal, erythrosine, and fluorescein having a group having a strong chemisorption property to zinc oxide such as a carboxylate group. Acid dyes such as
It is a dye that has an excellent sensitizing effect on zinc oxide. However, dyes such as methylene blue and crystal violet that do not have a group having a strong chemisorption property to zinc oxide are inferior in sensitizing effect to zinc oxide to acid dyes. Although it cannot be generally stated, a dye having a group having a strong chemisorption property to zinc oxide, such as a carboxylic acid group, a sulfonic acid group, or a salt thereof, tends to have a large sensitizing effect on zinc oxide. A dye that does not have a group having a strong chemisorption property to zinc tends to have a small sensitizing effect on zinc oxide. Therefore, in order to obtain a practical sensitizing property, there are restrictions such as selection and combination of specific sensitizing dyes.

Recently, a scanning exposure system using laser light has come into use. In this scanning exposure method using a laser beam, electronically edited information can be converted into an electric signal and laser-exposed to directly write image information on the photoconductor. Further, electronically edited information can be easily enlarged / reduced, converted to negative / positive, shaded, etc., and can have many functions, which is a great advantage over the conventional camera exposure method. As a laser light source used in this laser light scanning exposure system, a semiconductor laser (wavelength range: 700
(-1000 nm) is currently receiving attention.

A sensitizing dye having a sensitivity to a laser light source is required as a sensitizing dye for a zinc oxide electrophotographic photosensitive member used in a laser light scanning exposure system. As such sensitizing dyes, phthalocyanine compounds, polymethine cyanine dyes and the like are known. As a description of an electrophotographic photosensitive member using a phthalocyanine compound, Japanese Patent Application Laid-Open No. Sho 5
9-116760, JP-A-59-220753, JP-A-61-156132, JP-A-1-202758.
JP-A-3-48856, JP-A-3-50557, and the like, but phthalocyanine compounds have a small sensitizing effect on zinc oxide and have insufficient sensitivity, and such a photoreceptor is used as an offset master. When it is used as the above, it has a defect that the stain is not sufficiently made by the etchant and thus the background stain occurs and the printing durability becomes poor. Further, as a description of an electrophotographic photoreceptor using a polymethine cyanine dye as a sensitizing dye, for example, US Pat. No. 3619154, US Pat. No. 3,682,630, JP-A-57-46245, JP-A-58-42055,
JP-A-58-58554, JP-A-58-59453
JP-A-59-22053, JP-A-59-7835
No. 8, JP-A-60-26949, JP-A-59-783.
58, JP-A-60-26949, JP-A-62-22.
No. 0962, Japanese Patent Laid-Open No. 1-161253, and the like.
In the case of polymethine cyanine dyes as well as the above dyes,
A dye having a chemisorbable group on zinc oxide such as a carboxylic acid group, a sulfonic acid group or a salt thereof tends to have a larger sensitizing effect on zinc oxide than a dye having no chemisorbable group. . Therefore, in order to obtain a sensitizing property that is practically applicable, the polymethine cyanine dye may be limited to a specific one. Further, the electrophotographic offset master using the polymethine cyanine dye tends to be slightly more susceptible to stains during printing than the conventional electrophotographic offset master using the sensitizing dye having a sensitivity in the visible light region.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a compound for improving the sensitizing ability of a sensitizing dye for electrophotographic photoreceptors, which is said to have a small sensitizing effect, and also provides
Further, the present invention provides an electrophotographic offset master with less stains during printing.

[0008]

Means for Solving the Problems The inventors of the present invention have intensively studied in order to solve the above-mentioned problems. As a result, when a dye having a weak sensitizing effect and a compound represented by the above chemical formula 1 are used in combination, the sensitization is surprising. The present invention has been accomplished by finding an effect that the effect is improved and, at the same time, stains at the time of printing are also reduced.

That is, the present invention relates to an electrophotographic photoreceptor having a photoconductor layer comprising an inorganic photoconductor, a binder resin, a sensitizing dye and, if necessary, a sensitization aid on a conductive support. And an electrophotographic photoreceptor containing at least one compound represented by the above chemical formula 1.

In the formula of the compound represented by Chemical formula ¹ , R ¹ represents an alkyl group, an alkoxy group, a halogen atom, a nitro group or a cyano group. Z ¹ may or may not be present, but when Z ¹ is present, it represents an atomic group necessary for bonding to the aromatic ring to form a hydrocarbon ring. When Z ¹ is bonded to the aromatic ring to form a hydrocarbon ring, R ¹ , a carboxy group, a hydroxy group and a sulfo group may be substituted on the hydrocarbon ring. Although l, m, and n each independently represent an integer of 0 to 3, m and n are not 0 at the same time. k represents an integer of 1 to 2. M represents a hydrogen atom, an alkali metal salt or an organic ammonium salt.

Specific examples of the compound represented by Chemical formula 1 used in the present invention are shown below, but the scope of the compound is not limited to these.

[0012]

[Chemical 2]

[0013]

[Chemical 3]

[0014]

[Chemical 4]

[0015]

[Chemical 5]

[0016]

[Chemical 6]

[0017]

[Chemical 7]

[0018]

[Chemical 8]

[0019]

[Chemical 9]

[0020]

[Chemical 10]

[0021]

[Chemical 11]

[0022]

[Chemical 12]

[0023]

[Chemical 13]

[0024]

[Chemical 14]

[0025]

[Chemical 15]

[0026]

[Chemical 16]

[0027]

[Chemical 17]

[0028]

[Chemical 18]

[0029]

[Chemical 19]

[0030]

[Chemical 20]

In the present invention, the content of the compound of the present invention contained in the photoconductor layer varies depending on the kind of the sensitizing dye used, but is within the range of 0.001% by weight to 1% by weight based on zinc oxide. It can be used. Considering the effect of improving the sensitizing property of the sensitizing dye and preventing stains during printing, the amount used is more preferably within the range of 0.005% by weight to 0.5% by weight. If the amount used is less than the range, the sensitizing effect is extremely small and the stain preventing effect is weak. Also,
If the amount used exceeds the range, the sensitivity will be high, but the charging property and the dark charge retaining property will be deteriorated and the dispersion stability of the coating liquid for forming a photoconductor layer will be deteriorated.

Examples of dyes having absorption in the visible light region which can be used in the present invention include acidic dyes such as rose bengal, erythrosine and fluorescein, basic dyes such as methylene blue, auramine and crystal violet, and cyanine dyes. Among these dyes, the effect of improving the sensitizing property is greater when a dye having a weaker sensitizing property is used. The zinc oxide electrophotographic photoreceptor using such a sensitizing dye has sensitivity in the visible light region, and thus can be used as a camera exposure type electrophotographic photoreceptor using a light source such as a halogen lamp.

For a laser beam scanning exposure type electrophotographic photoreceptor, a polymethine cyanine dye or the like can be preferably used as a sensitizing dye. As the pometin-based cyanine dye for the laser beam scanning exposure type electrophotographic photoreceptor used in the present invention, the dye compound represented by Chemical formula 21 is preferable.

[0034]

[Chemical 21]

In the formula of the dye compound represented by Chemical formula 21, R ⁴
R ⁷ and R ^{7, which} may be the same or different, each represents an alkyl group, an alkenyl group or an aralkyl group which may have a substituent. R ² , R ³ , R ⁵ and R ^{6, which} may be the same or different, each represents an alkyl group. R ² and R ³ and R ⁵ and R ⁶ may form a hydrocarbon ring or a heterocycle together with the carbon atom at the 3-position of the nitrogen-containing ring, and the formed rings may be the same or different. . Z ² and Z ³
May be the same as or different from each other and represent an atomic group necessary for forming a benzene ring or a naphthalene ring. L represents a methine group, and p is 2 or 3. X ⁻ is an anion, q
Is 1 or 2 and is 1 when the dye forms an inner salt. The details will be described below.

R ⁴ and R ^{7, which} may be the same or different, each represents an alkyl group, an alkenyl group or an aralkyl group which may have a substituent. Specific examples of R ⁴ and R ⁷ include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, and n-pentyl group, alkenyl groups such as allyl group and methallyl group, and benzyl. Groups, aralkyl groups such as β-phenethyl group and α-naphthylmethyl group. Specific examples of the substituent include a sulfo group, a carboxy group, a phospho group, a hydroxy group, a halogen atom, an alkoxy group, a cyano group and the like. When the substituent is an acid substituent, N
It may be in the form of an alkali metal salt such as a and K, an alkaline earth metal salt such as Mg and Ca, an organic ammonium salt such as an ammonium salt, a triethylammonium salt, a tributylammonium salt and a pyridinium salt.

R ² , R ³ , R ⁵ and R ⁶ may be the same or different and each represents an alkyl group. As a specific example,
Examples thereof include lower alkyl groups such as methyl group and ethyl group. R ² and R ³ and R ⁵ and R ⁶ may form a hydrocarbon ring or a heterocycle together with the carbon atom at the 3-position of the nitrogen-containing ring. The rings formed may be the same as or different from each other, and are preferably 4- to 7-membered hydrocarbon rings or heterocycles. Specific examples of the hydrocarbon ring include cyclobutane, cyclopentane, cyclohexane, cycloheptane and the like. The hydrocarbon ring may have a substituent, and specific examples of the substituent include a lower alkyl group such as a methyl group and an ethyl group. Further, specific examples of the heterocycle include a tetrahydrofuran ring and a tetrahydropyran ring.

Z ² and Z ³ may be the same or different and each represents an atomic group necessary for forming a benzene ring or a naphthalene ring. Z ² and Z ³ may have a substituent,
Specific examples of the substituent include a sulfo group, a carboxy group, an alkyl group, an aralkyl group, an aryl group, a halogen atom,
Examples thereof include a cyano group, a nitro group, an alkoxy group, a hydroxy group, an alkoxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonamide group and a carboxamide group. When the substituent is an acid substituent, N
It may be in the form of an alkali metal salt such as a and K, an alkaline earth metal salt such as Mg and Ca, an organic ammonium salt such as an ammonium salt, a triethylammonium salt, a tributylammonium salt and a pyridinium salt.

The methine group represented by L is unsubstituted or substituted, and specific examples of the substituent include a halogen atom, an alkyl group, an aralkyl group, an aryl group, an alkoxy group and the like. Further, a 6-membered ring containing three methine groups in which the substituents are bonded to each other, such as 4,
4-dimethylcyclohexane or the like may be formed. Further, p representing the length of the methine chain is 2 or 3, and more preferably 3.

[0040] X ^- include anions represented by may be mentioned a halogen ion, a perchlorate ion, aryl sulfonate ion, an alkyl sulfate ion. Here, q is 1 or 2 and is 1 when the dye forms an intramolecular salt.

Specific examples of the dye compound represented by Chemical formula 21 used in the present invention are shown below, but the scope of the dye compound is not limited to these.

[0042]

[Chemical formula 22]

[0043]

[Chemical formula 23]

[0044]

[Chemical formula 24]

[0045]

[Chemical 25]

[0046]

[Chemical formula 26]

[0047]

[Chemical 27]

[0048]

[Chemical 28]

[0049]

[Chemical 29]

[0050]

[Chemical 30]

[0051]

[Chemical 31]

[0052]

[Chemical 32]

The dye compound represented by Chemical formula 21 used in the present invention can be synthesized by a conventionally known method. For example, Japanese Patent Laid-Open Nos. 2-187751 and 2-2
It can be synthesized by the methods described in JP-A No. 23944 and JP-A No. 3-95548.

The dye contained in the photoconductor layer may be used alone with the compound of the present invention, or two or more kinds of dyes may be used in combination. The content of the dye can be used in the range of 0.0001% to 2% by weight with respect to zinc oxide, and more preferably 0.000%.
It is within the range of 5% by weight to 1% by weight. If it is less than the range, the sensitizing effect is not seen, and if it is more than the range, the apparent sensitivity is improved, but the charging property and the dark charge retaining property are deteriorated. Regarding the sensitivity, the sensitivity can be adjusted also by the amount of the compound of the present invention 1 used in combination, and when adjusting the photoreceptor to the target sensitivity, the sensitivity is adjusted by the amount of the dye used and the amount of the compound of the present invention used. Two types of sensitivity adjustment methods, sensitivity adjustment, are possible. The sensitivity tends to increase as the amount of the compound of the present invention used increases, and high sensitivity can be achieved with a small amount of dye, which is advantageous in terms of cost.

The dye compound represented by Chemical formula 21 is also a dye having a group having a strong chemisorption property to zinc oxide, such as a carboxylic acid group, a sulfonic acid group, or a salt thereof, although it cannot be generally stated. The compound tends to have a larger sensitizing effect on zinc oxide than the dye compound having no group having strong chemisorption. Therefore, the effect of improving the sensitizing property when the compound represented by Formula 1 of the present invention is used in combination is a dye having a group having a strong chemisorption property to zinc oxide, such as a carboxylic acid group, a sulfonic acid group or a salt thereof. The effect of improving the sensitizing effect is greater when a dye having no group having a strong chemisorption property to zinc oxide is used, rather than a compound. Regarding the effect of improving stains during printing when the compound represented by the present invention is added, electrophotographic offset masters using any of the dye compounds are effective.

It is not clear why the addition of the compound represented by Formula 1 of the present invention to the dye having a weak sensitizing effect improves the sensitizing property of the dye, but a group having a strong chemisorption property to zinc oxide is not found. The reason for this is considered as follows, because the dyes that it has are highly sensitizing to zinc oxide, and the dyes that do not have a group with strong chemisorption tend to have a small sensitizing effect to zinc oxide. That is, when the compound of the present invention is added to a basic dye or polymethine cyanine dye having a weak sensitizing property, the sulfonic acid group of the compound of the present invention is replaced with the anion of the dye as a counter anion, and the zinc oxide adsorbing property of the compound of the present invention is The present inventors believe that the groups may be adsorbed on zinc oxide to increase the sensitizing effect of the dye.

When the compound of the present invention is used in combination with a dye as a sensitizing dye solution, the basic dye may have poor solubility in a solvent depending on the dye used or may be used as a coating liquid for forming a photoconductor layer. In some cases, the dispersion stability may be poor. On the other hand, the polymethine cyanine dye represented by Chemical formula 21 is preferable because it has good solubility in a solvent and is stable as a sensitizing dye solution.

Although no clear cause for the improvement of stain resistance during printing is known, the inclusion of the compound of the present invention in the photoconductor layer promotes the desensitizing reaction between zinc oxide and the etchant during etching. I think it will be done.

Zinc oxide as an inorganic photoconductor used in the photoconductor layer has photoconductivity, and it is preferable to use fine powder having an average particle size of about 0.1 to 1 μm. .

In the case of an electrophotographic photoconductor using zinc oxide as the inorganic photoconductor, a sensitization aid is used if necessary in order to adjust the electrophotographic characteristics. A cyclic acid anhydride is preferred as a sensitization aid for zinc oxide. Cyclic acid anhydrides include unsubstituted or substituted aliphatic dicarboxylic acid cyclic acid anhydrides and aromatic cyclic acid anhydrides.

Specific examples of the cyclic acid anhydride of the aliphatic dicarboxylic acid include succinic anhydride, methylsuccinic anhydride, ethylsuccinic anhydride, n-octylsuccinic anhydride and n-anhydride.
Succinic anhydrides such as octadecenyl succinic acid and anhydrous acetylmercaptosuccinic acid, maleic anhydride, and anhydrous 2-
Chloromaleic acid, dichloromaleic anhydride, anhydrous 2,
Maleic anhydride such as 3-dimethylmaleic acid, itaconic anhydride, citraconic anhydride, glutaric anhydride, adipic anhydride, isobutyric anhydride, diglycolic acid anhydride, cis
-Aconitic anhydride, anhydrous 5-norbornene-2,3
-Dicarboxylic acid etc. can be mentioned.

Specific examples of aromatic cyclic acid anhydrides include phthalic anhydride, 3-nitrophthalic anhydride, methoxyphthalic anhydride, methylphthalic anhydride, chlorophthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride,
Phthalic anhydrides such as cyanophthalic anhydride, cis-hexahydrophthalic anhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride, pyromellitic dianhydride, trimellitic dianhydride, diphenic anhydride, 1,8 -Naphthalic anhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'- Examples thereof include benzophenone tetracarboxylic acid dianhydride and cis-cyclohexene-1,2-dicarboxylic acid anhydride.

These cyclic acid anhydrides have the functions of interacting with the surface of zinc oxide, remarkably improving the charging property and charge retaining property of the photoreceptor and promoting the sensitizing effect of the sensitizing dye. is there.

The content of the cyclic acid anhydride contained in the photoconductor layer may be in the range of 0.001% by weight to 1% by weight with respect to zinc oxide, but 0.01% by weight to 0.
More preferably, it is within the range of 5% by weight. When the amount is less than the range, the effects on the charging property, the dark charge retaining property and the sensitizing property are not exhibited, and when the amount is more than the range, the apparent sensitivity is improved, but the charging property and the dark charge retaining property are significantly reduced. There is a case.

As the binder resin used in the photoconductor layer, all binder resins generally well known for electrophotographic photoreceptors can be used. For example, acrylic resin,
Binder resins such as styrene resin, silicone resin, polyester resin, epoxy resin, urethane resin, alkyd resin, vinyl chloride resin, vinyl acetate resin can be used, but when used as an electrophotographic offset master In terms of cost, sensitivity characteristics of the photoconductor layer, and printability, an acrylic resin is preferable.

As the acrylic resin, in addition to a single polymer such as acrylic acid ester or methacrylic acid ester, a copolymer of acrylic acid ester and methacrylic acid ester, and further acrylic acid ester or methacrylic acid ester and styrene, It may be a copolymer such as vinyl acetate. Further, it may be modified with acrylic acid, methacrylic acid, maleic acid, phthalic acid, crotonic acid, phthalic anhydride, tiglic acid, itaconic acid, citraconic acid, allylmalonic acid, or the like. These binder resins may be used alone, or two or more kinds of resins may be mixed and used.

The content of the binder resin contained in the photoconductor layer varies depending on the intended use. For example, when zinc oxide is used as an electrophotographic offset master, the content is 10% by weight to 30% by weight based on zinc oxide. It is preferably in the range of%, and if it is out of the range, the sensitivity is lowered and the printability such as background stain and printing durability is deteriorated, which is not preferable.

As the electroconductive support used in the electrophotographic photosensitive member of the present invention, various types can be used including known supports. Generally, the support of the electrophotographic photosensitive layer is preferably conductive, the surface is conductive, solvent resistance,
Water-resistant paper and plastic film, paper laminated with plastic, metal sheet, metal foil, paper and plastic film laminated with metal foil, and the like are used.

The coating liquid for forming the photosensitive layer of the electrophotographic photosensitive member according to the present invention contains a predetermined amount of an inorganic photoconductor, a binder resin, a sensitizing dye and, if necessary, a sensitizing auxiliary agent as an organic solvent. (For example, toluene, xylene, benzene, acetone,
It is prepared by mixing and dispersing it together with methyl ethyl ketone, etc. using a mixing and dispersing machine (for example, ball mill, sand grinder, paint conditioner, etc.).

The obtained coating solution is coated on the above support by a coating method such as a wire bar, a reverse roll or an air knife, and dried with hot air to form an electrophotographic photosensitive layer.
The thickness of the photoconductor layer affects printability in relation to charging property, sensitivity, etc., and is usually preferably 5 to 25 μm. More preferably, it is 10 to 20 μm.

The electrophotographic offset master using zinc oxide as the inorganic photoconductor has been described above.
In addition, titanium oxide, zinc sulfide, cadmium sulfide, or the like can be used as the inorganic photoconductor to similarly prepare an electrophotographic photoreceptor.

[0072]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 Photoconductive Zinc Oxide (Sazex # 2000 manufactured by Sakai Chemical Co., Ltd.)
100 parts by weight, phthalic anhydride 0.20 parts by weight, acrylic resin (Dianal LR-118 manufactured by Mitsubishi Rayon Co., Ltd.,
50 parts by weight of solid content (40%), 120 parts by weight of toluene, 0.06 parts by weight of methylene blue and 0.15 parts by weight of the compound of the present invention 2 were dissolved in 3.0 parts by weight of methyl alcohol to prepare a sensitizing dye solution. The mixture was mixed and kneaded with a porcelain ball mill for 2 hours to prepare a coating liquid for forming a zinc oxide photoconductor.
This photoconductor-forming coating liquid is applied to paper having conductivity, solvent resistance, and water resistance, and the thickness of the photoconductor layer after drying is about 15 μm.
It was applied with a wire bar so that

The obtained electrophotographic photosensitive member was heated at 20 ° C. and 65%.
After conditioning for 24 hours in the dark of RH atmosphere, electrophotographic characteristics were measured by the following measuring methods. Paper analyzer SP-428 manufactured by Kawaguchi Denki Co., Ltd. was used to measure the electrophotographic characteristics of the electrophotographic photosensitive member.
Was used. The photoconductor is charged by a static method, and the surface potential immediately after the charge is set to the initial charge potential V0.
(V), the ratio of the surface potential after the dark decay for 10 seconds after charging to the initial potential V0 is the dark decay retention rate D. D.
(%), The exposure amount required until the surface potential 10 seconds after charging becomes half the potential by exposure is the half exposure amount E1 /
2 (lux · sec), the surface potential 10 seconds after the start of exposure was used as the residual potential Vr (V), and the photoreceptor was evaluated. The measurement results are shown in Table 1.

Example 2 A photoconductor was prepared in the same manner as in Example 1 except that the dye was changed to 0.07 parts by weight of crystal violet and the compound of the present invention was changed to Chemical formula 4, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 1.

Example 3 A photoconductor was prepared in the same manner as in Example 1 except that the dye was changed to 0.157 parts by weight of Rose Bengal and the compound of the present invention was changed to Chemical formula 9, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 1.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1 except that the compound of the present invention was not used, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 1.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 2 except that the compound of the present invention was not used, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 1.

Example 4 As the dye, the heptamethine cyanine dye of Chemical formula 22 was used.
045 parts by weight of the compound of the formula 7 as a compound of the present invention.
A photoconductor was prepared by the same method as in Example 1 except that 04 parts by weight was used, and the electrophotographic characteristics were measured by the following measuring methods.

The obtained electrophotographic photosensitive member was heated at 20 ° C. and 65%
After conditioning for 24 hours in a dark place of RH, paper analyzer SP- manufactured by Kawaguchi Denki Co., Ltd.
An interference filter of 780 nm was set on the light source unit of 428, and the photoconductor was irradiated with the dispersed light to measure the electrophotographic characteristics. The charging of the photosensitive member is performed by a static method, and the surface potential immediately after charging is set to the initial charging potential V0 (V),
Initial potential V of surface potential after dark decay for 10 seconds after charging
The ratio to the dark decay retention rate D. D. (%), The amount of exposure required until the surface potential 10 seconds after charging becomes half the potential by light irradiation with 780 nm light is the half-exposure amount E1 / 2
(Erg / cm ² ) and the surface potential 10 seconds after the start of exposure was used as the residual potential Vr (V) to evaluate the photoreceptor. The measurement results are shown in Table 2.

Example 5 The heptamethine cyanine dye of Chemical formula 27 was used in an amount of 0.04.
A photoconductor was prepared in the same manner as in Example 4 except that the amount was changed to 0 part by weight, and the electrophotographic characteristics were evaluated. Table 2 shows the measurement results
Shown in.

Example 6 0.02 of the heptamethine cyanine dye of the chemical formula 29 was used.
A photoreceptor was prepared in the same manner as in Example 4 except that the amount was changed to 5 parts by weight, and the electrophotographic characteristics were evaluated. Table 2 shows the measurement results
Shown in.

Example 7 0.04 of the heptamethine cyanine dye of the chemical formula 31 was used.
A photoreceptor was prepared in the same manner as in Example 4 except that the compound of Chemical formula 8 was used as the compound of the present invention in an amount of 0.045 part by weight instead of 5 parts by weight, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 2.

Comparative Example 3 A photoconductor was prepared in the same manner as in Example 4 except that the compound of the present invention was not used, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 2.

Comparative Example 4 A photoconductor was prepared in the same manner as in Example 5 except that the compound of the present invention was not used, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 2.

Comparative Example 5 A photoconductor was prepared in the same manner as in Example 7 except that the compound of the present invention was not used, and the electrophotographic characteristics were evaluated. The measurement results are shown in Table 2.

[0087]

[Table 1]

[0088]

[Table 2]

As clearly shown in Tables 1 and 2, Example 1
Nos. 7 to 7 are high-sensitivity photoconductors, and Comparative Examples 1 to 5 to which the compound of the present invention is not added are low-sensitivity photoconductors. When a sensitizing dye solution is prepared by using the compound of the present invention and a dye in combination, the polymethine cyanine dye has better solubility in a solvent and stability when used as a coating liquid than the basic dye, and the sensitizing dye More preferred as a solution.

Example 8 The photoconductors of Examples 1 to 3 were subjected to plate making with a ZM-33S plate making machine (manufactured by Mitsubishi Paper Mills) using ZM-ED toner (manufactured by Mitsubishi Paper Mills Ltd.) to obtain plate-making products. In order to compare the stain resistance during printing, an etching converter OH-11 was prepared by using an etching solution prepared by diluting ZM-OH.N etching solution (non-cyan type etching solution, manufactured by Mitsubishi Paper Mills) with water twice.
(Manufactured by Mitsubishi Paper Mills) was etched once to obtain a printing plate.

Next, using these printing plates, TOKO-
2000CD offset printing machine (made by Tokyo Airlines Keiki Co., Ltd.)
Then, Guns ink (sumi) is used as the printing ink and ZM is used as the moisturizing liquid
Using OD (manufactured by Mitsubishi Paper Mills) diluted 9 times with water, printing was performed on high-quality paper, the 100th printed matter was sampled, and stains on the printed matter were evaluated. The 100th printed matter obtained from any of the printing plates was a printed matter with good image quality without print stains on the non-image area.

Comparative Example 6 When the photoconductors of Comparative Examples 1 and 2 were subjected to plate making and printing in the same manner as in Example 8, in each case, the printed matter was slightly soiled.

Example 9 The photoconductors of Examples 4 to 7 were processed with 1440ES Plates.
Plate making was carried out by using a toner (made by Printware) with a tter plate making machine (made by Printware) to make a plate. To compare the stain resistance during printing, ZM-O
A HII etchant (cyan type etchant, manufactured by Mitsubishi Paper Mills) was diluted with water to double the etching solution, and was etched once with an etching converter OH-11 (manufactured by Mitsubishi Paper Mills Ltd.) to obtain a printing plate.

Next, this printing plate was printed in the same manner as in Example 8, and the 100th printed material was sampled to evaluate the stains on the printed material. Printing stains did not occur in the non-image area, and the printed matter had good image quality.

Comparative Example 7 When the photoconductors of Comparative Examples 3 to 5 were made into a plate by the same method as in Example 8 and printed, the prints were all slightly stained.

[0096]

As described above, the use of the compound of the present invention together with a dye as a sensitizing dye for an electrophotographic photoreceptor improves the sensitizing property of the dye which has been conventionally considered to have a small sensitizing effect. be able to. If an electrophotographic photoreceptor containing the compound of the present invention is used as an offset master, it is possible to obtain an electrophotographic offset master in which stains hardly occur.

Claims (3)

[Claims] 1. An electrophotographic photoreceptor having a photoconductor layer comprising, on a conductive support, an inorganic photoconductor, a binder resin, a sensitizing dye, and optionally a sensitization aid, Chemical 1
An electrophotographic photoreceptor containing at least one kind of the compound shown in 1. [Chemical 1] (In the formula, R ¹ represents an alkyl group, an alkoxy group, a halogen atom, a nitro group or a cyano group. Z ¹ may or may not be present, but when Z ¹ is present, it is bonded to the aromatic ring. Represents a group of atoms necessary for forming a hydrocarbon ring, and when Z ¹ is bonded to the aromatic ring to form a hydrocarbon ring, R ¹ , a carboxy group, a hydroxy group and a sulfo group are The hydrocarbon ring may be substituted.l, m, and n each independently represent an integer of 0 to 3, but m and n are not 0 at the same time, and k represents an integer of 1 to 2. M represents a hydrogen atom, an alkali metal salt or an organic ammonium salt.) 2. The electrophotographic photoreceptor according to claim 1, wherein a polymethine cyanine dye is used as a sensitizing dye. 3. An electrophotographic offset master comprising the electrophotographic photosensitive member according to claim 2.