JPH07209887A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor having high sensitivity and high durability. CONSTITUTION:An azo compd. contg. a coupler component represented by the formula is incorporated as a photoconductive material into a layer on an electric conductive substrate. In the formula, Z is a residue required to form an arom. hydrocarbon group or an arom. heterocyclic group which may have a substituent by condensation with the benzene ring, X is a divalent combining group, Y is a residue required to form a 5- or 6-membered ring which may have a substituent or a condensed ring in combination with N and Q is Q or =CR<1>R<2> (each of R<1> and R<2> is H, an alkyl, aryl or a heterocyclic group which may have a substituent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor containing a novel azo compound.

[0002]

2. Description of the Related Art Inorganic photoconductive substances such as selenium, cadmium sulfide, zinc oxide, and silicon have been heretofore known for electrophotographic photoreceptors, and have been widely studied and put to practical use. . While these inorganic materials have many advantages, they also have various drawbacks. For example, selenium has drawbacks that it is difficult to produce under conditions and is easily crystallized by heat or mechanical shock, and cadmium sulfide and zinc oxide have poor moisture resistance and durability. It has been pointed out that silicon has insufficient chargeability and is difficult to manufacture. Furthermore, selenium and cadmium sulfide have toxicity problems.

On the other hand, organic photoconductive materials have good film-forming properties, excellent flexibility, light weight, good transparency, and are sensitized to a wide range of wavelengths by a suitable sensitizing method. Because of its advantages such as easy body design, its practical application is gradually gaining attention.

By the way, the photosensitive member used in the electrophotographic technique is generally required to have the following basic properties. That is, (1) high chargeability against corona discharge in the dark, (2) little leakage (dark decay) of the obtained charged charge in the dark, and (3) charge charging by light irradiation. The light is rapidly dissipated (4), and (4) there is little residual charge after light irradiation.

However, much research has been conducted on photoconductive polymers such as polyvinylcarbazole as an organic photoconductive substance to date, but these are not always sufficient in film formability, flexibility and adhesiveness. Also, it cannot be said that the photoconductor has the basic properties sufficiently.

On the other hand, regarding the organic low-molecular-weight photoconductive compound, by selecting a binder or the like used for forming the photoconductor, the photoconductor having excellent mechanical strength such as film-forming property, adhesive property and flexibility. However, it is difficult to find a compound suitable for retaining the highly sensitive property.

In order to improve such a point, the carrier generation function and the carrier transport function are shared by different substances,
Organic photoreceptors having higher sensitivity have been developed. The characteristic of such a photoconductor, which is called a function-separated type, is that materials suitable for each function can be selected from a wide range, and many studies have been carried out because a photoconductor having arbitrary performance can be easily prepared. Has been promoted.

As described above, various improvements have been made in the preparation of the electrophotographic photosensitive member, but the basic properties required for the photosensitive member and the high durability are satisfied. The current situation is that the products have not been obtained sufficiently.

[0009]

The object of the present invention is to have high sensitivity and high durability, a high charging potential, and a decrease in the sensitivity even after repeated use, and a stable charging potential. Another object of the present invention is to provide an electrophotographic photosensitive member.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted a study on a photoconductive substance having high sensitivity and high durability, and as a result, a novel azo compound containing a coupler component represented by the above chemical formula 1 is effective. The inventors have found that there is one, and have reached the present invention.

In Chemical Formula 1, Z represents a residue necessary for forming an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent by condensing with a benzene ring, and X represents a divalent group. A valent linking group is shown. Y represents a residue necessary for forming a 5-membered ring or 6-membered ring which may have a substituent or a condensed ring together with a nitrogen atom, and Q represents an oxygen atom or = CR ¹ R ² . . R ¹ and R ² represent a hydrogen atom, an alkyl group which may have a substituent, an aryl group, or a heterocyclic group.

Specific examples of R ¹ and R ² include hydrogen atom, alkyl groups such as methyl group, ethyl group, n-propyl group and isopropyl group, phenyl group, methoxyphenyl group, methylphenyl group and chlorophenyl group. And aryl groups such as naphthyl group and anthranyl group, and heterocyclic groups such as pyridyl group, furyl group and thienyl group. Specific examples of the aromatic ring and the heterocycle represented by Z include a benzene ring, a methylbenzene ring, a methoxybenzene ring, a chlorobenzene ring, a naphthalene ring, an anthracene ring, a furan ring, a pyridine ring, an ethylpyridine ring, a carbazole ring,
Examples thereof include a quinoline ring, a benzothiophene ring, a chlorobenzothiophene ring, a benzofuran ring, and a benzocarbazole ring. Specific examples of X and Y include the groups shown in the specific examples of Chemical formula 1 below.

Specific examples of the coupler represented by Chemical Formula 1 useful in the present invention include those represented by Chemical Formulas 2 to 51.

[0014]

[Chemical 2]

[0015]

[Chemical 3]

[0016]

[Chemical 4]

[0017]

[Chemical 5]

[0018]

[Chemical 6]

[0019]

[Chemical 7]

[0020]

[Chemical 8]

[0021]

[Chemical 9]

[0022]

[Chemical 10]

[0023]

[Chemical 11]

[0024]

[Chemical 12]

[0025]

[Chemical 13]

[0026]

[Chemical 14]

[0027]

[Chemical 15]

[0028]

[Chemical 16]

[0029]

[Chemical 17]

[0030]

[Chemical 18]

[0031]

[Chemical 19]

[0032]

[Chemical 20]

[0033]

[Chemical 21]

[0034]

[Chemical formula 22]

[0035]

[Chemical formula 23]

[0036]

[Chemical formula 24]

[0037]

[Chemical 25]

[0038]

[Chemical formula 26]

[0039]

[Chemical 27]

[0040]

[Chemical 28]

[0041]

[Chemical 29]

[0042]

[Chemical 30]

[0043]

[Chemical 31]

[0044]

[Chemical 32]

[0045]

[Chemical 33]

[0046]

[Chemical 34]

[0047]

[Chemical 35]

[0048]

[Chemical 36]

[0049]

[Chemical 37]

[0050]

[Chemical 38]

[0051]

[Chemical Formula 39]

[0052]

[Chemical 40]

[0053]

[Chemical 41]

[0054]

[Chemical 42]

[0055]

[Chemical 43]

[0056]

[Chemical 44]

[0057]

[Chemical formula 45]

[0058]

[Chemical formula 46]

In order to obtain an azo pigment containing the coupler component represented by the chemical formula 1 of the present invention, an amine represented by the following chemical formula 47 (in the formula, B is an organic residue, and n is an integer of 1 to 4). Can be diazotized by a conventional method, and the obtained diazotized solution is reacted with the coupler represented by Chemical formula 1 in the presence of an alkali.

[0060]

[Chemical 47]

Specific examples of the azo pigment containing the coupler component represented by the chemical formula 1 of the present invention include those having the following structural formulas. In the formula, A represents a coupler of Chemical formula 1.

[0062]

[Chemical 48]

[0063]

[Chemical 49]

[0064]

[Chemical 50]

[0065]

[Chemical 51]

[0066]

[Chemical 52]

[0067]

[Chemical 53]

[0068]

[Chemical 54]

[0069]

[Chemical 55]

[0070]

[Chemical 56]

[0071]

[Chemical 57]

[0072]

[Chemical 58]

[0073]

[Chemical 59]

[0074]

[Chemical 60]

[0075]

[Chemical formula 61]

[0076]

[Chemical formula 62]

[0077]

[Chemical formula 63]

[0078]

[Chemical 64]

[0079]

[Chemical 65]

[0080]

[Chemical formula 66]

[0081]

[Chemical formula 67]

[0082]

[Chemical 68]

[0083]

[Chemical 69]

[0084]

[Chemical 70]

[0085]

[Chemical 71]

[0086]

[Chemical 72]

[0087]

[Chemical formula 73]

[0088]

[Chemical 74]

[0089]

[Chemical 75]

[0090]

[Chemical 76]

[0091]

[Chemical 77]

[0092]

[Chemical 78]

[0093]

[Chemical 79]

[0094]

[Chemical 80]

[0095]

[Chemical 81]

[0096]

[Chemical formula 82]

[0097]

[Chemical 83]

[0098]

[Chemical 84]

[0099]

[Chemical 85]

[0100]

[Chemical 86]

[0101]

[Chemical 87]

Next, a synthesis example will be specifically described. Synthetic Example (Synthesis of Exemplified Compound 67 (Coupler: Chemical 23)) 2,7-Diaminofluorenone (0.42 g) was added to DMF.
(30 ml) and 6N hydrochloric acid (2.0 ml) and dissolved at about 5 ° C in an aqueous solution of sodium nitrite (0.42 g) (1
ml) was added. After 30 minutes, the obtained diazotized solution was added to a DMF solution (30 ml) containing coupler 23 (2.66 g) and triethanolamine (1.35 g) in an amount of 5 to 10 minutes.
The solution was added dropwise at 10 ° C over 10 minutes. After stirring at the same temperature for 2 hours and further at room temperature for 2 hours, the precipitate was collected by filtration and washed with 200 ml each of DMF and water. Yield 1.98 g Yield 89% Melting point 250 ° C or higher

The electrophotographic photosensitive member of the present invention can be obtained by containing one kind or two or more kinds of azo compounds containing the coupler component shown in Chemical formula 1. Various types of photoreceptors are known, and any of them can be used. For example, there is one in which a photosensitive layer made of an azo compound, a charge transport material, and a film-forming binder resin is provided on a conductive support. Further, there is also known a laminated type photoreceptor in which a charge generation layer composed of an azo compound and a binder resin and a charge transport layer composed of a charge transport substance and a binder resin are provided on a conductive support. Either the charge generation layer or the charge transport layer may be the upper layer. If necessary, an undercoat layer may be provided between the conductive support and the photosensitive layer, an overcoat layer may be provided on the surface of the photoreceptor, and an intermediate layer may be provided between the charge generation layer and the charge transport layer in the case of a laminated type photoreceptor. Can be provided.
As a support for forming a photoreceptor using the compound of the present invention, a metal drum, a metal plate, a conductive processed paper, a sheet of plastic film, a drum-shaped or belt-shaped support, etc. are used. .

As the film-forming binder resin used for forming the photosensitive layer on those supports, various resins can be mentioned depending on the field of use. For example, in the application of photoconductor for copying, polystyrene resin, polyvinyl acetal resin, polysulfone resin, polycarbonate resin, polyester resin, polyphenylene oxide resin, polyarylate resin, acrylic resin, methacrylic resin, phenoxy resin and the like can be mentioned. Among these, polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polyester resin, polyarylate resin and the like are excellent in potential characteristics as a photoreceptor. Further, these resins can be used alone or as a copolymer by mixing two or more kinds.

The content of these resins contained in the photosensitive layer is preferably 10 to 500% by weight with respect to the azo pigment, and 50 to 1% by weight.
50% by weight is more preferred. If the ratio of the resin is too high, the charge generation efficiency is lowered, and if the ratio of the resin is too low, the film formability becomes a problem.

Some of these resins include tension, bending,
Some have weak mechanical strength such as compression. To improve this property, plasticizing agents can be added. Specifically, phthalate ester (for example, DOP, D
BP, etc., phosphoric acid ester (eg TCP, TOP
Etc.), sebacic acid ester, adipic acid ester, nitrile rubber, chlorinated hydrocarbon and the like. If these substances are added more than necessary, the electrophotographic characteristics are adversely affected, so the proportion thereof is preferably 20% or less relative to the binder resin.

In addition, an antioxidant, an anti-curl agent or the like can be added as an additive to the photosensitive member, if necessary.

The charge transport material includes a hole transport material and an electron transport material. As an example of the former, for example, Japanese Patent Publication No. 34-5
Oxadiazoles shown in Japanese Patent Publication No. 466, triphenylmethanes shown in Japanese Patent Publication No. 45-555, pyrazolines shown in Japanese Patent Publication No. 52-18888, Japanese Patent Publication No. 55-42380. Hydrazones disclosed in JP-A-56-123544, oxadiazoles disclosed in JP-A-56-123544, and JP-B-58-3237.
Examples thereof include the triarylamines disclosed in JP-A No. 2 and the stilbenes disclosed in JP-A No. 58-198043. On the other hand, examples of the electron transport material include chloranil, tetracyanoethylene, 2,
4,7-trinitro-9-fluorenone, 2,4,5,
7-tetranitroxanthone, 1,3,7-trinitrodibenzothiophene and the like. These charge transport materials can be used alone or in combination of two or more.

[0109]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Example 1 1 part by weight of Exemplified Compound Chemical Formula 67 (Coupler: Chemical Formula 17) and 1 part by weight of a polyester resin (Vylon 200 manufactured by Toyobo) were mixed with 100 parts by weight of tetrahydrofuran, and the mixture was mixed with glass beads for 2 hours by a paint conditioner device. Dispersed. The dispersion thus obtained was coated on aluminum vapor-deposited polyester with an applicator to form a charge generation layer having a thickness of about 0.2 μm. Next, p-dibenzylaminobenzaldehyde = diphenylhydrazone was mixed with a polyarylate resin (U-polymer manufactured by Unitika) at a weight ratio of 1: 1 to prepare a 10% solution using dichloroethane as a solvent to prepare the above charge generation layer. Was applied with an applicator to form a charge transport layer having a thickness of about 20 μm.

The laminated photoconductor thus prepared is
Electrophotographic characteristic evaluation was performed using an electrostatic recording tester (SP-428 manufactured by Kawaguchi Denki). Measurement conditions: Applied voltage -6 kV, Static No. 3 (turntable rotation speed mode: 10 m / min
). As a result, the charging potential V0 is -740 V, and the half exposure amount E1 / 2
Showed a high sensitivity value of 1.4 lux · sec.

Further, using the same apparatus, characteristics evaluation was carried out for repeated use in which one cycle of charging-discharging (eliminating light: irradiation with white light of 400 lux × 1 second) was set as one cycle. 5000
When the change in charging potential due to repetition was calculated, 1
It was found that the initial potential at the 5000th time was −730V, whereas the initial potential at the 5000th time was −740V, and there was little decrease in the potential due to repetition and the stability was stable.

Examples 2 to 4 Photosensitive members were prepared in the same manner as in Example 1 except that the azo pigments shown in Table 1 were used, and their characteristics were evaluated. The results are shown in Table 1.
Shown in.

[0114]

[Table 1]

Example 5 1 part by weight of Exemplified Compound 67 (coupler: 17) and 40 parts by weight of tetrahydrofuran were dispersed together with zirconia beads in a ball mill for 48 hours. 2.5 parts by weight of N-ethylcarbazole-3-carbaldehyde = diphenylhydrazone and polycarbonate resin (PCZ-200; manufactured by Mitsubishi Gas Chemical Co., Inc.) were added to the dispersion liquid thus obtained.
After adding 0 part by weight and 60 parts by weight of tetrahydrofuran and further performing an ultrasonic dispersion treatment for 2 minutes, it is applied on aluminum vapor-deposited polyester with an applicator to give a film thickness of about 1
A 5μ photoreceptor was formed. The electrophotographic characteristics of this photoreceptor were measured in the same manner as in Example 1. However, only the applied voltage was changed to +5 kV. As a result, excellent characteristics with high sensitivity and little change such as +640 kV, half-exposure amount of 1.3 lux · sec, initial potential after repeating 5000 times +600 kV, and half-exposure amount of 1.5 lux · sec were shown.

Examples 6 to 9 Photosensitive members were prepared in the same manner as in Example 5 except that the azo pigments shown in Table 2 were used, and their characteristics were evaluated. The results are shown in Table 2.
Shown in.

[0117]

[Table 2]

Comparative Examples 1 and 2 A photoconductor was prepared in the same manner as in Example 1 except that azo compounds 88 and 89 were used, and the characteristics were evaluated. The results are shown in Table 3.

[0119]

[Chemical 88]

[0120]

[Chemical 89]

[0121]

[Table 3]

Comparative Examples 3 and 4 A photoreceptor was prepared in the same manner as in Example 5 except that azo compounds 88 and 89 were used, and the characteristics thereof were evaluated. The results are shown in Table 4.

[0123]

[Table 4]

[0124]

As is apparent from the above, according to the present invention, an electrophotographic photosensitive member having high sensitivity and high durability can be provided.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing an azo compound containing a coupler component represented by the following chemical formula 1 on a conductive support. [Chemical 1] (In Chemical Formula 1, Z represents a residue necessary for forming an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent by being condensed with a benzene ring, and X represents a divalent group. Represents a linking group, Y represents a residue necessary for forming a 5-membered ring or 6-membered ring which may have a substituent or a condensed ring together with a nitrogen atom, and Q represents an oxygen atom or = CR ¹ R
² is shown. R ¹ and R ² represent a hydrogen atom, an alkyl group which may have a substituent, an aryl group, or a heterocyclic group. )