JPH0695403A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having high sensitivity and high durability. CONSTITUTION:A compd. represented by formula I or II is incorporated into a layer on an electric conductive substrate. In the formulae I, II, X is a residue of in arom. or hetero ring which is condensed to a benzene ring and may have a substituent, Y is a combining group, each of R<1>-R<4>, R<6> and R<7> is H or alkyl and R<5> is H, optionally substd. alkyl, aralkyl or acyl.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Inorganic photoconductive substances such as selenium, cadmium sulfide, zinc oxide, and silicon have been conventionally known for electrophotographic photoreceptors, and have been widely studied and put into practical use. . While these inorganic materials have many advantages, they also have various drawbacks. For example, selenium has drawbacks that it is difficult to manufacture under conditions and is easily crystallized by heat or mechanical impact, 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. In addition, 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, but these are not necessarily 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 photosensitive member, a photosensitive member excellent in mechanical strength such as film-forming property, adhesion and flexibility can be obtained. Although obtainable, it is difficult to find a suitable compound that can retain the highly sensitive properties.

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 such as the development of new materials and combinations thereof have been made in order to satisfy the requirements such as basic performance and high durability required for electrophotographic photoreceptors. However, it has not yet reached a sufficient level.

One major problem is that when the photoconductor is actually used in a copying machine, the photoconductor is strongly oxidized by ozone or the like generated from a charger. A photoreceptor made of an organic material is susceptible to this oxidizing action, and as a result, the charging potential and the sensitivity are lowered. As a countermeasure, a method of adding various antioxidants to the photoconductor has been conventionally proposed. However, these methods are not always effective, and on the contrary,
There have been problems such as deterioration of sensitivity and increase of residual potential.

As a result of detailed investigations on the deterioration of the photoreceptor, the present inventors were able to clarify that the use of a specific compound having an antioxidant ability can effectively prevent these oxidation effects. .

[0011]

The object of the present invention is that the charging potential is high and the sensitivity is high, the charging potential and the sensitivity are hardly deteriorated even if it is repeatedly used, and the oxidation action by ozone or the like is prevented. An object is to provide an electrophotographic photoreceptor having high resistance.

The present inventors have studied photoconductive materials having high sensitivity and high durability, and as a result,
The present invention has been completed by finding that the novel antioxidant represented by is effective.

In the chemical formulas ¹ and 2, X is an aromatic ring or a heterocyclic residue which may have a substituent condensed with a benzene ring, Y is a linking group, and R ^{1 to} R ⁴ , R ⁶ and R ⁷ Is a hydrogen atom or an alkyl group, and R ⁵ is a hydrogen atom, an optionally substituted alkyl group, an aralkyl group, or an acyl group.

Specific examples of the aromatic ring and heterocyclic ring represented by X are benzene ring, methylbenzene ring, methoxybenzene ring, chlorobenzene ring, naphthalene ring, anthracene ring, furan ring, pyridine ring, ethylpyridine ring and carbazole. Examples thereof include a ring, a quinoline ring, a benzothiophene ring, a chlorobenzothiophene ring, a benzofuran ring and a benzocarbazole ring. Specific examples of Y include the groups shown in the specific examples of Chemical Formula 1 below. Specific examples of R ^{1 to} R ⁴ , R ⁶ and R ⁷ include a hydrogen atom, an alkyl group such as a methyl group, an ethyl group and an isopropyl group. Specific examples of R ⁵ include hydrogen atom, methyl group, ethyl group, 2-chloroethyl group, 2-
Alkyl group such as hydroxyethyl group, benzyl group, 4-
Examples thereof include aralkyl groups such as methylbenzyl group, 4-chlorobenzyl group and 2-phenylethyl group, and acyl groups such as formyl group, acetyl group and benzoyl group.

Specific examples of the compound represented by Chemical formula 1 are:
For example, those having the following structural formulas can be mentioned.

[0016]

[Chemical 3]

[0017]

[Chemical 4]

[0018]

[Chemical 5]

[0019]

[Chemical 6]

[0020]

[Chemical 7]

[0021]

[Chemical 8]

[0022]

[Chemical 9]

[0023]

[Chemical 10]

[0024]

[Chemical 11]

[0025]

[Chemical 12]

[0026]

[Chemical 13]

[0027]

[Chemical 14]

[0028]

[Chemical 15]

[0029]

[Chemical 16]

[0030]

[Chemical 17]

[0031]

[Chemical 18]

[0032]

[Chemical 19]

[0033]

[Chemical 20]

[0034]

[Chemical 21]

[0035]

[Chemical formula 22]

[0036]

[Chemical formula 23]

[0037]

[Chemical formula 24]

[0038]

[Chemical 25]

[0039]

[Chemical formula 26]

[0040]

[Chemical 27]

[0041]

[Chemical 28]

[0042]

[Chemical 29]

[0043]

[Chemical 30]

[0044]

[Chemical 31]

[0045]

[Chemical 32]

[0046]

[Chemical 33]

[0047]

[Chemical 34]

[0048]

[Chemical 35]

[0049]

[Chemical 36]

[0050]

[Chemical 37]

[0051]

[Chemical 38]

[0052]

[Chemical Formula 39]

[0053]

[Chemical 40]

[0054]

[Chemical 41]

[0055]

[Chemical 42]

[0056]

[Chemical 43]

Specific examples of the compound represented by Chemical formula 2 are:
For example, those having the following structural formulas can be mentioned.

[0058]

[Chemical 44]

[0059]

[Chemical formula 45]

[0060]

[Chemical formula 46]

[0061]

[Chemical 47]

[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]

Next, a synthesis example will be specifically described. Synthesis Example 1 (Synthesis of Chemical Formula 11) 3-Hydroxy-2-naphthoic acid phenyl ester (1.32 g) and 4-amino-2,2,6,6-tetramethylpiperidine (1.09 g) were added at 170 ° C. for 90 minutes. After heating for minutes and allowing to cool, the precipitated crystals were recrystallized from ethyl acetate (65 ml) to obtain Chemical formula 11. Yield 1.27 g, melting point 219-222 ° C.

Synthesis Example 2 (Synthesis of Chemical Formula 18) 3-Hydroxy-2-naphthoic acid hydrazide (4.04)
g), 2,2,6,6-tetramethyl-4-piperidone hydrochloride (3.83 g), sodium acetate (1.64)
A mixture of g) and ethanol (75 ml) was heated for 30 minutes and allowed to cool, and the precipitate was collected by filtration and washed with ethanol and hot water. The crude product was recrystallized from DMF (107 ml) to obtain compound 18. Yield 2.74 g Melting point 187.9-188.1 ° C

Synthesis Example 3 (Synthesis of Chemical Formula 20) 3-Hydroxy-2-naphthoic acid hydrazide (4.04)
g), N-benzyl-4-piperidone (3.78 g),
A mixture of acetic acid (0.5 ml) and ethanol (75 ml) was heated for 90 minutes, allowed to cool, and the precipitate was collected by filtration. The crude product was recrystallized from dioxane (77 ml) and DMF (5 ml) to obtain compound 20. Yield 5.77g Melting point 176.5 ° C (decomposition)

Synthesis Example 4 (Synthesis of Chemical Formula 49) 3-Hydroxy-2-naphthoic acid hydrazide (1.01)
A mixture of g), 3,5-di-t-butyl-4-hydroxybenzaldehyde (1.17 g) and ethanol (15 ml) was heated for 35 minutes, allowed to cool, and the precipitate was collected by filtration. The crude product was dissolved in DMSO (12 ml) with heating, and methanol (34 ml) was added for crystallization to obtain Compound 49. Yield 1.12g Melting point 297 ° C (decomposition)

The electrophotographic photosensitive member of the present invention can be obtained by containing one kind or two or more kinds of the compounds shown in Chemical formula 1 or Chemical formula 2. Various types of photoreceptors are known, and any of them can be used. For example, a single-layer type photoreceptor in which a photosensitive layer made of a charge generating substance, a charge transporting substance, and a film-forming binder resin is provided on a conductive support, or made of a charge generating substance and a binder resin Examples thereof include a laminated-type photoreceptor provided with a charge generation layer and a charge transport layer composed of a charge transport material and a binder resin. Either the charge generation layer or the charge transport layer may be the upper layer. The content of the compound represented by Chemical formula 1 or 2 is 0.1 to 5 of the charge generating substance in the single-layer type photoreceptor.
% By weight, 0.1 to 5% by weight of the charge generating substance in the charge generating layer of the multilayer type photoreceptor, and 0.1 to 5% by weight of the charge transporting substance in the charge transporting layer.

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 or a belt-like support, etc. may be used. used. Further, 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, more preferably 50 to 150% by weight, based on the charge generating substance in the charge generating layer of the multi-layer type photoreceptor. On the other hand, in the charge transport layer of the single-layer type photoconductor and the multi-layer type photoconductor, it is 50 to 1 relative to the charge transport substance.
50% by weight is preferred.

Some of these resins include pulling, 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 to the compounds of the present invention, an antioxidant, an anti-curl agent, etc. can be added as an additive to the photoreceptor, if necessary.

As the charge generating substance used in combination with the compound of the present invention, pyrylium dyes such as benzopyrylium and benzothiapyrylium, cyanine dyes such as thiacyanine and oxacyanine, squarylyl dyes, phthalocyanine pigments, and anthanthrone dyes. Pigments, indigo pigments, quinacridone pigments, azo pigments and the like can be mentioned, but among these, the combination with the azo pigment works most effectively.

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.

[0097]

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. The following azo pigments and charge transfer substances were used in each example.

[0098]

[Chemical 72]

[0099]

[Chemical formula 73]

[0100]

[Chemical 74]

[0101]

[Chemical 75]

[0102]

[Chemical 76]

[0103]

[Chemical 77]

Example 1 Azo pigmented 72 (1 part by weight), polyester resin (Vylon 200 manufactured by Toyobo; 1 part by weight), 18 (0.02 parts by weight), and tetrahydrofuran (100 parts by weight) were mixed, Dispersed with glass beads for 2 hours with a paint conditioner device. 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. Then 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, and the applicator was applied on the charge generation layer. Was applied 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 condition: Applied voltage-6k
V, static No. 3 (turntable rotation speed mode: 10 m / min). As a result, the charging potential V0
Shows a high sensitivity value of −700 V and a half-exposure amount E1 / 2 of 1.3 lux · sec. Also, using the same device,
The charging-exposure was repeated a number of times, but almost no change was observed in the charging potential and the half-exposure amount.

Next, this photoreceptor was left in an ozone atmosphere of 25 ppm for 5 hours, and the electrophotographic characteristics were measured again using the same apparatus. As a result, the charging potential V0 is -670.
V, half-exposure amount E1 / 2 was 1.3 lux · sec, which was almost unchanged.

Example 2 Azo pigmented 72 (1 part by weight), 18 (0.02 parts by weight) and tetrahydrofuran (100 parts by weight) were mixed and dispersed for 2 hours together with glass beads by a paint conditioner device. In the dispersion liquid thus obtained,
10 parts by weight of N-ethylcarbazole-3-carbaldehyde = diphenylhydrazone, 10 parts by weight of a polycarbonate resin (PCZ-200; manufactured by Mitsubishi Gas Chemical Co., Inc.), and 40 parts by weight of tetrahydrofuran were added, and the mixture was further dispersed for 1 hour by a paint conditioner device, It was coated on aluminum vapor-deposited polyester with an applicator to form a photoreceptor having a film thickness of about 20 μm. 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, the charging potential before ozone treatment was +630 kV and the half exposure was 1.4 lux.
Sec., Charging potential after ozone treatment + 570V, half exposure 1.4 lux.sec., With high sensitivity and little change,
It showed excellent properties.

Examples 3 to 8 Photosensitive members were prepared in the same manner as in Example 2 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.

[0109]

[Table 1]

Examples 9 to 14 Azo-pigmented 72 (1 part by weight), polyester resin (Byron 200 manufactured by Toyobo; 1 part by weight), and tetrahydrofuran (100 parts by weight) were mixed together and 2 together with glass beads using a paint conditioner device. Time 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, the charge transfer substance (1 part by weight) shown in Table 2 and the compound of the present invention (0.01 part by weight) were dissolved in tetrahydrofuran (10 parts by weight) together with a polyarylate resin (U-polymer manufactured by Unitika; 1 part by weight). It melt | dissolved and it apply | coated with the applicator on the said charge generation layer, and formed the 20-micrometer-thick charge transport layer. About this photoreceptor
The electrophotographic characteristics were obtained in the same manner as in Example 1. The results are shown in Table 2.

[0111]

[Table 2]

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1 except that the chemical formula 18 was not included, and its characteristics were evaluated. As a result, before the ozone treatment, the charging potential V0 was -720V and the half exposure amount E1 was
Although / 2 was 1.3 lux · sec, after the ozone treatment, the charging potential V0 was −590 V and the half-exposure amount E1 / 2 was 1.5 lux · sec, which was a large deterioration in characteristics.

Comparative Examples 2 to 4 Photoreceptors were prepared in the same manner as in Example 2 except that the azo pigments shown in Table 3 were not included in the compound of the present invention, and their characteristics were evaluated. The results are shown in Table 3.

[0114]

[Table 3]

[0115]

As is apparent from the above, according to the present invention, it is possible to provide an electrophotographic photosensitive member having high sensitivity, high durability, and high resistance to the oxidation effect of ozone and the like.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a compound represented by the following chemical formula 1 or chemical formula 2 on a conductive support. [Chemical 1] [Chemical 2] (In Chemical Formula 1 and Chemical Formula 2, X is an aromatic ring or a heterocyclic residue which may have a substituent condensed with a benzene ring, Y is a linking group, and R ^{1 to} R ⁴ , R ⁶ and R ⁷ are hydrogen. An atom or an alkyl group, and R ⁵ is a hydrogen atom, an optionally substituted alkyl group, an aralkyl group, or an acyl group.)