JPH04296760A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body having superior photosensitivity by forming a photosensitive layer contg. a specified azo pigment as an electric charge generating material on an electrically conductive substrate. CONSTITUTION:A photosensitive layer contg. a novel azo pigment represented by formula I is formed on an electrically conductive substrate to obtain a photosensitive body. The azo pigment can be synthesized by bringing a coupler component represented by formula II and a diazonium salt represented by a general formula Ar(NH2)n into a coupling reaction. In the formulae, R is a hydrocarbon group which may have a substituent, A is alkyl, hydroxyalkyl, alkoxyalkyl, allyl, aralkyl or a heterocyclic group, Ar is an arom. hydrocarbon group or a heterocyclic group which may bond through a bonding group and n is an integer of 1-4. The diazonium salt is arom. mono-, di-, tri- or tetramine.

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 on 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, the charge generation function and charge transport function in the photoconductive function are individually assigned to different substances, resulting in high sensitivity and repeated stability.
A functionally separated photoreceptor with excellent durability has been developed.

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]

Furthermore, 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-63-172167 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, characterized in that the photosensitive layer contains a novel azo pigment represented by the following general formula (I). shall be.

0012

[C4]

(In the formula, R is a hydrocarbon group which may have a substituent, A is an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, an allyl group, an aralkyl group, or a heterocyclic group, and Ar is a bonding group. represents an aromatic hydrocarbon group or a heterocyclic group which may be bonded via
Or indicates the number 4. ) General formula (I) used in the present invention
) The method for producing the azo pigment will be described below.

[0014] The azo pigment of the present invention is, for example, a coupler component represented by the following general formula (III) and a general formula Ar(
It can be synthesized by a coupling reaction of NH2)n (wherein Ar and n are mono-, di-, tri- or tetraamine aromatic groups represented by the same meanings as above) with a diazonium salt. Such a coupling reaction is carried out according to a known method, usually in water and/or an organic solvent such as 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 are the same as defined above) The coupler component represented by the general formula (III) is, for example,
According to reaction formula (1) shown below, 4-(4-alkoxyphenyl)-5H-pyran-2,6-dione (IV) and aromatic amine (V) are heated in a solvent such as pyridine,
4-(4-alkoxyphenyl)-5H-1-alkyl(allyl)pyrido-2 obtained by dehydration condensation
, 6-dione (VI) and acetic anhydride, reaction formula (2)
obtained according to.

[0017]

[C6]

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 is formed by dispersing an azo pigment as a main component 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 of 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 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 charge transporting material is preferably 80% by weight or less, preferably 25 to 75% by weight, based on the binder resin in the photosensitive layer.

When 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.

[0023] If the charge transport material itself is a polymeric charge transport material that can be used as a binder, no other binder resin may be used.

[0024] 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.

By the way, 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 and aryl groups such as

In the general formula (I), A represents an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, an allyl group, an aralkyl group or a heterocycle.

Examples of the alkyl group include hydrocarbon groups that may have side chains, such as methyl, ethyl, n-propyl, iso-propyl, and n-butyl groups.

Examples of the hydroxyalkyl group include methoxymethyl group, methoxyethyl group, methoxypropyl group, ethoxymethyl group, and ethoxyethyl group. Examples of the allyl group include a phenyl group, an alkyl group, an alkylphenyl group, an alkoxyphenyl group, a halogenated phenyl group, a naphthyl group, and a methylnaphthyl group.

Examples of the aralkyl group include benzyl group, diphenyl group, methyl group, phenethyl group, and styryl group.

In the general formula (I), A represents sensitivity, spectral sensitivity,
When considering repeat stability, etc., alkyl groups such as methyl and ethyl, hydroxyalkyl groups such as hydroxymethyl and hydroxyethyl, alkoxyalkyl groups such as methoxy and ethoxy, allyl groups such as phenyl and naphthyl, and aralkyl groups such as benzyl. , pyridine, pyrazole and the like are preferred.

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. As the aromatic hydrocarbon group which may be bonded via a bonding group, the following general formula (V
Divalent groups such as the bisphenylene group represented by II); and trivalent groups derived from triphenylamine, triphenylmethane, 9-phenylfluorene, etc. can also be mentioned.

[0035]

[C7]

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 3 parts by weight of a 40% methylamine solution were dissolved and stirred in 60 parts by weight of pyridine, and reacted for 30 minutes at the boiling point of pyridine. After the reaction, the reaction solution was cooled to room temperature and diluted with 300 ml to 400 ml of a 9% acetic acid aqueous solution.
ml, and the precipitated crystals were collected by filtration, washed with water, dried, and recrystallized with methanol. The obtained crystals were pale yellow-green plate-like crystals that melted at 200°C. Based on elemental analysis and infrared absorption spectrum, this crystal is 4-(4-methoxyphenyl)-
It was found to be 5H-1-methylpyrido-2,6-dione. The yield was 2 parts by weight, and the elemental analysis values were as follows.

[0044]

[Table 3]

The above 4-(4-methoxyphenyl)-5H
2.8 parts by weight of -1-methylpyrido-2,6-dione 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 are colorless needle-like crystals with 14
It melted at 0°C. Elemental analysis and infrared absorption spectra revealed that this crystal was 2-acetyl-4-(4-methoxyphenyl)-5H-1-methylpyrido-2,6-dione. The yield was 2.5 parts by weight, and the elemental analysis values were as follows.

[0046]

[Table 4]

The above 2-acetyl-4-(4-methoxyphenyl)-5H-1-methylpyrido-2,6-dione 2
．． 3 parts by weight and 2.5 parts by weight of tetrafluoroborate of dichlorobenzidine were dissolved in 200 ml of N,N-dimethylformamide (DMF), and a solution of 3 g of sodium acetate dissolved in 50 ml of water was added to the solution at 10 to 20°C. It was added dropwise over 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. DMF this cake
After dispersing in 400 ml and stirring at room temperature for 3 hours, the mixture was filtered again. After repeating this operation twice, the crystals were washed with water and dried. The obtained solid had a deep reddish-purple color and was heated at 300°C.
I did not disassemble it below. This material was identified as the target bisazo pigment based on elemental analysis and infrared absorption spectrum. The yield was 1.8 parts by weight, and 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 12

[0052]

[Chemical formula 8]

1 having a structure corresponding to the above general formula (VIII), where A and R are 1 to 12 shown in Table 1;
Two types of bisazo pigments 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 to form a charge generation layer. 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.

[0055] The 12 types of photoreceptors thus prepared were first charged by -6.5 KV corona discharge in a dark place.
Next, it was 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 Table 6.

The half-decreased exposure amount of the photoreceptor in Example 1 was 2.2L.
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 significant improvement in sensitivity of 60% was observed. Furthermore, for the photoreceptors of Examples 2 to 12, the same method was applied to JP-A-63-1
When compared with the photoreceptor described in Japanese Patent No. 72167, an improvement in sensitivity of 25 to 50% was confirmed.

[0057]

[Table 6]

Examples 13-28

[0059]

[Chemical formula 9]

1 having a structure corresponding to the above general formula (IX) and in which Cp and Ar are 13 to 28 shown in Table 2.
Six types of bisazo pigments were synthesized. Sixteen 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 photoreceptor, the half-decreased exposure amount (
E1/2) was measured and the results are shown in Tables 7 and 8.

The half-decreased exposure amount of the photoreceptor in Example 13 is 2.5
Lux·sec, which is approximately A significant improvement in sensitivity of 48% was observed. Furthermore, when the photoreceptors of Examples 14 to 28 were similarly compared, it was confirmed that the sensitivity was improved by 30 to 50%, respectively.

[0062]

[Table 7]

[0063]

[Table 8]

Examples 29 to 40 Example 1 was prepared using the azo pigment used in Examples 1 to 12 as the charge generating material and N-ethylcarbazole-3-aldehydemethylphenylhydrazone as the charge transporting material.
Twelve types of photoreceptors were produced in the same manner as described above. Further, for each photoconductor, the value of half-decreased exposure (E1/2) was measured as the sensitivity and is shown in Table 9.

The half-decreased exposure amount of the photoreceptor of Example 29 was 3.5
Lux·sec, which is approximately A significant improvement in sensitivity of 45% was observed. Furthermore, when comparing the photoreceptors of Examples 30 to 40 in the same way,
An improvement in sensitivity of 25 to 50% was confirmed in each case.

[0066]

[Table 9]

Comparative example 1

[0068]

[Chemical formula 10]

A comparative example was prepared in the same manner as in Example 1, except that the bisazo pigment (X) described in JP-A-63-172167 was used as a charge-generating material in place of the bisazo pigment in Example 1. A photoreceptor was produced. As a result of measuring the sensitivity using this photoreceptor under the same conditions as in the example, the half-decreased exposure amount was 5.5 Lux·sec.

Comparative example 2

[0071]

[Chemical formula 11]

Example 13 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 of Example 13.
A comparative photoreceptor was prepared in the same manner as described above. Using this photoreceptor, sensitivity was measured under the same conditions as in the example.
The half-reduction exposure value was 4.8 Lux·sec.

Comparative example 3

[0074]

[Chemical formula 12]

Comparative photosensitization was carried out in the same manner as in Example 29, except that the bisazo pigment (X) described in JP-A-63-172167 was used as the charge-generating material in place of the bisazo pigment in Example 29. The body was created. Using this photoreceptor, the sensitivity was measured under the same conditions as in the above example, and as a result, the half-decrease exposure amount was 6.3 Lux·sec.

[0076]

[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 alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, an allyl group, an aralkyl group, or a heterocyclic group, Ar represents an aromatic hydrocarbon group or a heterocyclic group that may be bonded via a bonding group, and n is Indicates the number 1, 2, 3 or 4. )