JPH04296761A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain the photosensitive body having an excellent photosensitivity by providing a photosensitive layer contg. a specific azo pigment on a conductive base. CONSTITUTION:The photosensitive layer to be provided on the conductive base contains the novel azo pigment expressed by formula I. In the formula I, R denotes a hydrocarbon group which may have a substituent; A denotes the bivalent group of arom. hydrocarbon or the bivalent group of a heterocycle contg. a nitrogen atom within the ring. Ar denotes an arom. hydrocarbon group or heterocyclic group which may be bonded via a bonding group; n denotes 1 to 4 integer. This azo pigment is produced by the process for synthesizing the dye by a coupling reaction of the coupler component expressed by, for example, formula II and formula III and the diazonium salt of general formula Ar(NH2)n, where Ar and n are the arom. mono-, di-, tri- or tetraamine expressed synonymously with the formula I. This coupling reaction is usually effected for about 1 to 10 hours at 30 to 25 deg.C in water and/or org. solvent, such as N, N-dimethyl formamide.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor containing a novel azo pigment in its photosensitive layer.

0002

BACKGROUND OF THE INVENTION Conventional photoreceptors are known to have a photosensitive layer mainly composed of an inorganic photoconductive substance and those having a photosensitive layer mainly composed of an organic photoconductive substance. Inorganic materials have drawbacks such as high toxicity, poor film-forming properties, lack of flexibility, and high manufacturing costs.

On the other hand, research into the use of organic photoconductive substances, typified by polyvinylcarbazole compounds, in the photosensitive layer of photoreceptors has progressed and has already been put into practical use. In general, organic photoconductive materials have better transparency, are lighter, and have better film-forming properties than inorganic photoconductive materials, but are inferior in sensitivity, durability, and stability against environmental changes. Therefore, a functionally separated photoreceptor has been developed in which the charge generation function and the charge transport function in the photoconductive function are assigned to different substances, and is highly sensitive, has excellent repeatability stability, and durability.

Organic pigments such as phthalocyanine pigments, cyanine pigments, condensed polycyclic quinone pigments, and perylene derivatives are known as typical charge-generating materials. These and suitable charge transport materials, such as amine compounds, pyrazoline compounds, oxadiazole compounds, carbazole compounds,
Alternatively, a functionally separated photoreceptor produced by combining it with a hydrazone compound has not yet been sufficiently satisfactory for practical use.

[0005] In recent years, techniques using various bisazo pigments as charge-generating materials have been proposed.
4-79632 and JP-A-57-176055 disclose a photoreceptor having a photosensitive layer containing a naphthalic acid imide-based (bis)azo pigment in which the coupler component shown in Chemical formula 2 mainly has a naphthol structure. is disclosed.

[0006]

[Case 2]

In order for a bisazo pigment to function effectively as a charge generating substance, it is said that it is necessary to have a structure that exhibits fluorescence, and JP-A-63-172166 discloses that it has the following general formula (II ) Azo pigments having fluorescent properties are disclosed.

[0008]

[Chemical formula 3]

[0009]

[Problems to be Solved by the Invention] However, none of the photoreceptors containing the (bis)azo pigments described in the above-mentioned publications are necessarily satisfactory in sensitivity, and further improvement in sensitivity is desired. .

Therefore, an object of the present invention is to provide a photoreceptor with excellent photosensitivity by using a highly sensitive new azo pigment as a charge generating material for an organic photoreceptor.

[0011]

[Means for Solving the Problems] The present invention provides a photoreceptor having a photosensitive layer on a conductive support, in which the photosensitive layer contains a novel azo pigment represented by the following general formula (I). Features.

0012

[C4]

(In the formula, R is a hydrocarbon group which may have a substituent, A is a divalent aromatic hydrocarbon group or a heterocyclic divalent group containing a nitrogen atom in the ring, and Ar is Indicates an aromatic hydrocarbon group or a heterocyclic group which may be bonded via a bonding group, and n indicates a number of 1, 2, 3 or 4.) Azo pigment of general formula (I) used in the present invention The manufacturing method is described below.

The azo compound of the present invention is, for example, a coupler component represented by the following general formulas (III-a) and (III-b) and a general formula Ar(NH2)n (wherein Ar and n are as defined above). It can be synthesized by a coupling reaction of a mono-, di-, tri- or tetraamine) with a diazonium salt. Such a coupling reaction is usually carried out according to a known method.
The reaction is carried out in an organic solvent such as water and/or N,N-dimethylformamide at a reaction temperature of 30 to 25° C. or less for about 1 to 10 hours.

[0015]

[C5]

(wherein A and R have the same meanings as above) The coupler components represented by the general formulas (III-a) and (III-b) can be, for example, 4 according to the reaction formula (1) shown below. -(4-alkoxyphenyl)-5H-pyran-
3-(4-alkoxyphenyl)-1-oxo- obtained by heating 2,6-dione (IV) and aromatic diamine (V) in a solvent such as pyridine and dehydrating condensation.
Obtained by 1H,5H-pyrido[1,2-a]benzimidazole (VI) and acetic anhydride according to reaction formula (2) (Dyes and Pigments), Volume 4, Page 35 (1983).

[0017]

[C6]

[0018] The azo pigment obtained by the above production method is a mixture of isomers of the general formulas (VII-a) and (VII-b) shown below, but any of the isomers can be used in the present invention. It is possible.

[0019]

[C7]

The photoreceptor of the present invention has a photosensitive layer containing an azo pigment as a charge generating material represented by the general formula (I), and can take various forms as shown below.

For example, a single-layer type photoreceptor in which a photosensitive layer formed by dispersing an azo pigment in a binder resin or a charge transport medium is provided on a conductive support, or a photoreceptor in which a photosensitive layer containing an azo pigment as a main component is provided on a support; It may be a so-called laminated photoreceptor in which a generation layer is provided and a charge transport layer is provided thereon.

When the photoreceptor of the present invention is a dispersion type in which a photosensitive layer is formed on a conductive support, the azo pigment represented by the general formula (I) is contained in the photosensitive layer. Such a photoreceptor is produced by dissolving or dispersing an azo pigment together with a binder resin in a suitable solvent, adding a charge transporting material if necessary, applying the resulting coating solution onto a conductive support, and drying it. A photoreceptor is produced. At this time, regarding the blending ratio of the azo pigment in the photosensitive layer, if it is too small, sufficient sensitivity will not be obtained, and if it is too large, problems such as poor charging and poor film formation will occur. It is preferable to add 0.5 to 50% by weight, more preferably 0.5 to 5% by weight. In addition, the thickness of the photosensitive layer is usually 5 to 30 μm,
The thickness is preferably 6 to 20 μm. The amount of the electric charge transport material is preferably 80% by weight or less, preferably 25 to 75% by weight, based on the binder resin in the photosensitive layer.

Further, in the case where the photoreceptor of the present invention is of a functionally separated type in which a charge generation layer and a charge transport layer are laminated on a conductive support, the charge generation layer has a compound represented by the general formula (I). The azo pigment of the present invention is contained. Such photoreceptors are produced by coating a conductive support with a coating solution prepared by dispersing the azo pigment of the present invention in a solution containing a binder resin, and drying the coating solution to form a charge generation layer. , apply a solution of a charge transport material and a binder resin dissolved in a suitable solvent thereon,
It is produced by drying to form a charge transport layer. At this time, the thickness of the charge generation layer is 0.01 to 5 μm, preferably 0.05 μm.
~2 μm, and the content of the azo pigment is 0.5 to 50% by weight, preferably 0.5% by weight based on the binder resin of the charge generation layer.
~5% by weight. In addition, the thickness of the charge transport layer is 2 to 10
0 μm, preferably 10 to 20 μm, the amount of charge transport material is 10 to 80% by weight based on the binder resin of the charge transport layer,
Preferably it is 25 to 75% by weight.

Examples of the charge transporting substance used in the photoreceptor of the present invention include hydrazone compounds, pyrazoline compounds, triphenylamine compounds, oxadiazole compounds, triphenylmethane compounds, and polyester compounds of anthracene derivatives. . Specifically, N
-ethylcarbazole-3-aldehyde methylphenylhydrazone (MPH), diethylaminobenzaldehyde diphenylhydrazone (DEH), and the like.

[0025] If the charge transporting material itself is a polymeric charge transporting material that can be used as a binder, no other binder resin may be used.

[0026] Here, the binder resin used for manufacturing the photoreceptor as described above is electrically insulating and desirably has a volume resistivity of 1×10 14 Ω·cm or more when measured alone. Specifically, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers),
Thermoplastic binders such as styrene-butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide; epoxy resin, urethane resin, silicone resin, phenol resin, melamine resin, xylene resin, alkyd Resins, thermosetting binders such as thermosetting acrylic resins; photocurable resins; photoconductive resins such as poly-N-carbazole, polyvinylpyrene, polyvinylanthracene, etc., but are not limited to these. do not have.

The photoreceptor of the present invention may be one in which a charge transport layer and a charge generation layer are laminated in this order on a conductive support.

Further, a surface protective layer may be provided on the surface of the photosensitive layer of the photoreceptor, or an intermediate layer may be provided on the conductive support.

Incidentally, in the general formula (I), R is a hydrocarbon residue which may have a substituent, and specifically, R is a methyl group, an ethyl group, a linear or branched propyl group, a butyl group, etc. group, alkyl group such as pentyl group, hexyl group, hydroxyalkyl group, alkoxyalkyl group, alkoxycarbonylalkyl group, acyloxyalkoxyalkyl group, hydroxyalkoxyalkyl group, alkoxyalkoxyalkyl group, aryloxyalkyl group, acyloxyalkyl group Substitutions such as cyanoalkyl, aminoalkyl, N'N-dialkylaminoalkyl, alkylaminoalkyl, halogenated alkyl, carboxyalkyl, morpholinoalkyl, alkylthioalkyl, arylthioalkyl, etc. Alkyl group having a group, cycloalkyl group such as cyclohexyl group, benzyl group, aralkyl group such as phenethyl group, phenyl group, chlorphenyl group, methoxyphenyl group, nitrophenyl group, tolyl group, xylyl group, alkylaminophenyl group Examples include aryl groups such as groups.

In the general formula (I), A represents a divalent aromatic hydrocarbon group or a divalent heterocyclic group containing a nitrogen atom in the ring. Examples of divalent groups of aromatic hydrocarbons include divalent groups of monocyclic aromatic hydrocarbons such as o-phenylene group, o-
Examples include divalent groups of condensed polycyclic aromatic hydrocarbons such as a naphthylene group, a peri-naphthylene group, a 1,2-anthraquinonylene group, and a 9,10-phenanthrylene group.

Further, examples of the divalent group in the heterocycle containing a nitrogen atom in the ring include 3,4-pyrazolediyl group, 2
, 3-pyridinediyl group, 4,3-pyrimidinediyl group, 6,7-imidazolediyl group, 5,6-benzimidazolediyl group, 6,7-quinolinediyl group, etc.
Examples include a divalent heterocyclic group containing a 10-membered nitrogen atom in the ring.

In consideration of sensitivity, spectral sensitivity, repetition stability, etc., aryl groups, particularly phenyl and naphthyl groups, are preferred. In the present invention, two of these aromatic hydrocarbons
The heterocyclic divalent group containing a valence group and a nitrogen atom in the ring may have a substituent. Such substituents include, for example, alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, n-hexyl group; methoxy group, ethoxy group , alkoxy groups such as propoxy groups and butoxy groups; hydroxy groups; nitro groups; cyano groups; halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; alkoxycarbonyl groups such as carboxyl groups and ethoxycarbonyl groups; carbamoyl groups ; aryloxy groups such as phenoxy; aralkoxy groups such as benzyloxy; and aryloxycarbonyl groups such as phenyloxycarboxy. Among them, alkyl groups, alkoxy groups, nitro groups, halogen atoms, hydroxy groups, carboxyl groups, and particularly methyl groups, methoxy groups, nitro groups, chlorine atoms, and hydroxy groups are preferable.

In the general formula (I), Ar represents an aromatic hydrocarbon or a heterocyclic group which may be bonded via a monovalent to tetravalent bonding group.

Examples of aromatic hydrocarbons include monovalent groups of monocyclic or condensed polycyclic aromatic hydrocarbons such as phenyl group, naphthyl group, 1-vinylene group, 2-anthryl group, and 5-acenaphthenyl group. ; Phenylene group, 1,3- or 1,4-naphthylene group, 2,6-anthraquinolene group,
Divalent groups of monocyclic or condensed polycyclic aromatic hydrocarbons such as 2,7-fluorenylene group and pyrenylene group; and other divalent groups such as biphenylene group. The aromatic hydrocarbon group which may be bonded via a bonding group has the following general formula (
Divalent groups such as bisphenylene group represented by VIII); and trivalent groups derived from triphenylamine, triphenylmethane, 9-phenylfluorene, etc.

[0035]

[Chemical formula 8]

Examples of the heterocyclic group include a 9- to 20-membered heterocyclic monovalent group such as a naphtoylenebenzimidazolyl group, a benzimidazolyl group, a benzoxazolyl group, a carbazolyl group, a benzothiazolyl group, and a quinolyl group; 9- to 20-membered heterocyclic divalent groups such as carbazolediyl group, benzothiophenediyl group, dibenzoquinonediyl group, dibenzothiophenediyl group, and benzothiophene oxide diyl group; 3 such as N-phenylcarbazoletriyl group
Examples include valence groups.

In the present invention, these aromatic hydrocarbon groups and heterocyclic groups may have a substituent. Specifically, nitro group; halogen atom such as cyano group, chlorine atom, bromine atom; methyl group, ethyl group, n-propyl group, n-
Alkyl groups such as butyl groups; alkoxy groups such as methoxy, ethoxy, and propoxy groups; aryl groups such as phenyl groups; arylamino groups such as phenylamine groups; aryloxy groups such as phenoxy groups; styryl group, naphthylvinyl group Examples include arylvinyl groups such as. Among them, nitro group, cyano group, methyl group, chlorine atom, especially nitro group,
A cyano group is preferred.

Next, a typical synthesis example of the bisazo pigment used in the present invention will be shown.

[0039]

[Synthesis example] After stirring 25 parts by weight of citric acid and 75 parts by weight of concentrated sulfuric acid at room temperature for about 30 minutes, the temperature was slowly raised to 70°C.
The reaction was carried out for about 10 to 15 minutes. At that time, a large amount of CO2
occurs. After the reaction, the mixture was cooled to room temperature, 10 parts by weight of anisole was added, and the mixture was reacted at room temperature for 2 hours. 150c of reaction solution
The precipitated crystals were collected by filtration, thoroughly washed with cold distilled water until the pH reached ~7, and then recrystallized with distilled water and dried. The crystals obtained were pale yellow needle-like crystals with a molecular weight of 175~
Decomposed at 176°C. Elemental analysis and infrared absorption spectra revealed that this crystal was 4-(4-methoxyphenyl)-glutaconic acid. The yield was 3 parts by weight, and the elemental analysis values were as follows.

[0040]

[Table 1]

5 parts by weight of the 4-(4-methoxyphenyl)-glutaconic acid was dissolved in 15 parts by weight of acetic anhydride and stirred,
The reaction was carried out under the boiling point of acetic anhydride for 25 minutes. After the reaction, the mixture was cooled to room temperature, and the precipitated crystals were collected by filtration, thoroughly washed with dry ether, and then dried. The crystals obtained were light yellowish brown needle-like crystals with 1
It melted at 60°C. Based on elemental analysis and infrared absorption spectrum, this crystal is 4-(4-methoxyphenyl)-5H
-pyran-2,6-dione. The yield was 4 parts by weight, and the elemental analysis values were as follows.

[0042]

[Table 2]

The above 4-(4-methoxyphenyl)-5H
2 parts by weight of -pyran-2,6-dione and 1 part by weight of o-phenylenediamine were dissolved and stirred in 30 parts by weight of acetic acid, and reacted for 30 minutes at the boiling point of acetic acid. After the reaction, the mixture was cooled to room temperature, and the precipitated crystals were collected by filtration, washed with methanol, and then dried. The obtained crystals were pale yellow plate-like crystals that melted at 310°C. Based on elemental analysis and infrared absorption spectrum, this crystal is 3-
(4-methoxyphenyl)-1-oxo-1H,5H-
It was found to be pyrido[1,2-a]benzimidazole. The yield was 2.2 parts by weight, and the elemental analysis values were as follows.

[0044]

[Table 3]

The above 3-(4-methoxyphenyl)-1-
3 parts by weight of oxo-1H,5H-pyrido[1,2-a]benzimidazole and 3 parts by weight of molten sodium acetate were dissolved and stirred in 30 parts by weight of acetic anhydride, and reacted for 2 hours at the boiling point of acetic anhydride. After the reaction, the mixture was cooled to room temperature, and the crude crystals collected by filtration were dried and recrystallized from anhydrous ethanol. The obtained crystals were colorless needle crystals and melted at 196°C. Based on the elemental analysis value and infrared absorption spectrum, this crystal is 2-acetyl-3-
(4-methoxyphenyl)-1-oxo-1H,5H-
pyrido[1,2-a]benzimidazole, and 4-
It was found to be acetyl-3-(4-methoxyphenyl)-1-oxo-1H,5H-pyrido[1,2-a]benzimidazole. The yield was 2.4 parts by weight, and the elemental analysis values were as follows.

[0046]

[Table 4]

The above 2-acetyl-3-(4-methoxyphenyl)-1-oxo-1H,5H--pyrido[1,2
-a]benzimidazole and 4-acetyl-3-(
2.9 parts by weight of 4-methoxyphenyl)-1-oxo-1H,5H-pyrido[1,2-a]benzimidazole and 2.5 parts by weight of tetrafluoroborate of dichlorobenzidine were mixed with N,N-dimethylformamide (DMF )200
ml, add 3 g of sodium acetate to this and 50 ml of water.
was added dropwise at 10 to 20°C over about 30 minutes. After the dropwise addition, the mixture was further stirred at room temperature for 3 hours, and the precipitated crystals were collected by filtration. The obtained crude crystal cake was dispersed in 400 ml of DMF, stirred at room temperature for 3 hours, and then filtered again. After repeating this operation twice, the crystals were washed with water and dried. The obtained solid had a deep purple color and did not decompose at temperatures below 300°C. This material was identified as the target bisazo pigment based on elemental analysis and infrared absorption spectrum. Yield: 2.0 parts by weight
The elemental analysis values were as follows.

[0048]

[Table 5]

[0049] The present invention will be specifically explained below with reference to Examples, but the embodiments of the present invention are not limited thereto.

[0050]

EXAMPLES The azo pigments of the present invention used in the following examples were synthesized according to the above synthesis example or a method similar thereto.

Examples 1 to 16

[0052]

[Chemical formula 9]

Sixteen types of bisazo pigments having structures corresponding to the above general formula (IX) and in which A and R are 1 to 16 as shown in Table 1 were synthesized.

0.45 parts by weight of the above bisazo pigment, polyester resin (manufactured by Toyobo Co., Ltd., trademark Vylon-200)
0.45 parts by weight was dispersed with 50 parts by weight of cyclohexanone using a sand grinder. The resulting bisazo pigment dispersion was applied onto a 100 μm thick aluminized mylar using a film applicator to give a dry film thickness of 0.3 g/m2.
A charge generation layer was formed by coating and drying. On top of this, a solution of 70 parts by weight of diethylaminobenzaldehyde diphenylhydrazone and 70 parts by weight of polycarbonate resin (manufactured by Teijin Kasei Co., Ltd., trademark K-1300) dissolved in 400 parts by weight of 1,4-dioxane was added until the dry film thickness was 1.
A charge transport layer was formed by coating to a thickness of 6 μm.

The 16 types of photoreceptors produced in this way were first charged by -6.5 KV corona discharge in a dark place.
Next, they were exposed to white light with an illuminance of 5 Lux, and the exposure amount required for the surface potential to attenuate to half of the initial surface potential (half-reduction exposure amount (E1/2)) was measured, and the results are shown in Tables 6 and 7.

The half-decreased exposure amount of the photoreceptor in Example 1 was 1.9L.
ux·sec, and compared to the half-decreased exposure amount of the photoreceptor of Comparative Example 1, which will be described later, was prepared using an azo pigment having the same A and R as in Example 1 in the general formula (II). A sensitivity improvement of 55% was observed. Furthermore, Examples 2 to 1
Similarly, regarding the photoreceptor No. 6, Japanese Patent Application Laid-Open No. 63-17216
When compared with the photoreceptor described in Publication No. 6, each
An improvement in sensitivity of 0% was confirmed.

[0057]

[Table 6]

[0058]

[Table 7]

Examples 17-33

[0060]

[Chemical formula 10]

It has a structure corresponding to the above general formula (X) and C
17 such that p and Ar are 17 to 33 shown in Table 2
A standard bisazo pigment was synthesized. Seventeen types of photoreceptors were produced in the same manner as in Example 1, except that these bisazo pigments were used in place of the bisazo pigments in Example 1. For each photoconductor, the half-decreased exposure amount (E
1/2) and the results are shown in Tables 8 and 9.

The half-decreased exposure amount of the photoreceptor in Example 17 was 1.7.
Lux·sec, which is approximately A sensitivity improvement of 57% was observed. Furthermore, Example 18
〜33 photoreceptors are also compared in the same way, each with 2
An improvement in sensitivity of 5 to 65% was confirmed.

[0063]

[Table 8]

[0064]

[Table 9]

Examples 34 to 49 Example 1 was prepared using the azo pigment used in Examples 1 to 16 as a charge generating material and N-ethylcarbazole-3-aldehydemethylphenylhydrazone as a charge transporting material.
Sixteen types of photoreceptors were produced in the same manner as described above. Further, for each photoreceptor, the value of half-decreased exposure (E1/2) was measured as sensitivity and is shown in Tables 10 and 11.

The half-decreased exposure amount of the photoreceptor of Example 34 was 2.2
Lux·sec, which is approximately An improvement in sensitivity of 61% was observed. Furthermore, Example 35
A similar comparison was made for the photoreceptors of 49 to 3, respectively.
An improvement in sensitivity of 0 to 60% was confirmed.

[0067]

[Table 10]

[0068]

[Table 11]

Comparative example 1

[0070]

[Chemical formula 11]

A photoreceptor was prepared in the same manner as in Example 1, except that the bisazo pigment (XI) described in JP-A-63-172167 was used as the charge-generating material in place of the bisazo pigment in Example 1. Created. Using this photoreceptor, the sensitivity was measured under the same conditions as in Example 1. As a result, the half-decrease exposure amount was 4.2 Lux·sec.

Comparative example 2

[0073]

[Chemical formula 12]

Example 1 except that the bisazo pigment (XII) described in JP-A-63-172167 was used as the charge generating material in place of the bisazo pigment of Example 17.
A photoreceptor was prepared in the same manner as described above. Using this photoreceptor, sensitivity was measured under the same conditions as in Example 17, and as a result, the half-decrease exposure amount was 4.0 Lux·sec.

Comparative Example 3

[0076]

[Chemical formula 13]

A photoreceptor was prepared in the same manner as in Example 1, except that the bisazo pigment (XI) described in JP-A-63-172167 was used as the charge-generating material in place of the bisazo pigment in Example 33. Created. Using this photoreceptor, sensitivity was measured under the same conditions as in Example 34, and as a result, the half-decrease exposure amount was 5.6 Lux·sec.

[0078]

[Effects of the Invention] As is clear from the above results, in the photoreceptor of the present invention, by having a photosensitive layer containing a novel azo pigment, the photosensitivity of the photoreceptor itself could be improved.

Claims (1)

[Claims] 1. A photoreceptor comprising a photosensitive layer containing an azo pigment represented by formula (I) on a conductive support. [Formula 1] (wherein, R is a hydrocarbon group which may have a substituent, A
represents an aromatic hydrocarbon divalent group or a heterocyclic divalent group containing a nitrogen atom in the ring, Ar represents an aromatic hydrocarbon group or a heterocyclic group that may be bonded via a bonding group, n is 1
, 2, 3 or 4. )