JPH05150521A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body having high sensitivity and excellent durability. CONSTITUTION:A photosensitive layer contg. an azo compd. represented by the formula is formed on an electric conductive substrate. In the formula, R<1> is H, halogen, alkyl, alkoxy, aryl, amino, cyano, nitro or sulfoxide and A is a residue of a coupler having the properties of an acceptor.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to an electrophotographic photosensitive member used in an electrostatic copying machine, a laser beam printer or the like.

[0002]

2. Description of the Related Art The Carlson process is widely used to form a copied image using an electrophotographic photosensitive member. The Carlson process consists of a charging process that uniformly charges the photoconductor by corona discharge, an exposure process that exposes the document image on the charged photoconductor to form an electrostatic latent image corresponding to the document image, and an electrostatic latent image. A developing step of developing with a developer containing toner to form a toner image, a transfer step of transferring the toner image to a base material such as paper, a fixing step of fixing the toner image transferred to the base material, and a transfer step. After the step, a cleaning step of removing the toner remaining on the photoconductor is included.

In order to form a high quality image in the Carlson process, the electrophotographic photosensitive member is required to have excellent charging characteristics and photosensitive characteristics and to have a low residual potential after exposure.

Conventionally, inorganic photoconductors such as selenium and cadmium sulfide have been known as electrophotographic photosensitive materials, but they are toxic and are not desirable because of high production cost.

Therefore, in place of these inorganic substances, so-called organic electrophotographic photoreceptors using various organic substances which are excellent in processability and advantageous in terms of manufacturing cost and have a high degree of freedom in functional design. Is proposed. Such an organic electrophotographic photosensitive member usually has a photosensitive layer composed of a charge generating material that generates an electric charge upon exposure and a charge transporting material that has a function of transferring the generated electric charge.

In order to satisfy various conditions desired for such an organic electrophotographic photoreceptor, it is necessary to appropriately select these charge generating material and charge transporting material. As the charge generating material, many compounds such as phthalocyanine compounds, perylene compounds, quinacridone compounds, ansanthrone compounds, azo compounds have been proposed. For example, as azo compounds, those disclosed in JP-A-47-37543 and JP-A-57-195767 are known.

However, the above-mentioned conventional charge generating materials have problems that the photosensitive wavelength region is narrow, the sensitivity is low, or the photostability is insufficient, and a photoreceptor containing these charge generating materials is present. However, it was inferior in sensitivity and durability.

Therefore, the present applicant has proposed an electrophotographic photoreceptor containing a new azo compound in order to solve the above problems. (Japanese Patent Application No. 3-243862)

[0009]

However, as a result of intensive studies by the present inventors, the inventors found that the uneven distribution of the electron density has a great influence on the improvement of the efficiency of electrification and the stability of repetition.

Therefore, the present invention has higher sensitivity,
It is also an object of the present invention to provide an excellent electrophotographic photosensitive member having improved characteristics such as excellent durability.

[0011]

The electrophotographic photosensitive member of the present invention for solving the above problems contains an azo compound represented by the following general formula (I) on a conductive substrate. It is characterized in that a photosensitive layer is provided.

[0012]

[Chemical 2]

[Wherein R ¹ is a hydrogen atom, a halogen atom,
An alkyl group, an alkoxy group, an aryl group, an amino group, a cyano group, a nitro group, a sulfoxide group, and A represents a coupler residue having an acceptor property] According to the studies by the present inventors, the above general formula (I) The bisazo pigment represented is represented by the following formula (II)

[0014]

[Chemical 3]

An acceptor core portion represented by:
Formula (III) below

[0016]

[Chemical 4]

Since the coupler residue portion having a moderate donor property represented by is fixed, a coupler residue having a strong acceptor property is introduced into A as the other coupler residue. , The electron density distribution of the molecules is biased, and the sensitivity is remarkably improved. That is, the polarization of the molecule in the excited state becomes large due to the bias of the electron density distribution of the molecule, the charge generation efficiency is improved by the strength of the internal polarization of the pigment, and the charge transport material is enhanced by the interaction with the charge transport material. It is possible to improve the efficiency of carrier injection into.

In the azo compound represented by the general formula (I), examples of the coupler residue A having an acceptor property include groups represented by the following general formulas (a) to (f).

[0019]

[Chemical 5]

In each formula, R ⁴ is a hydroxyl group, a group represented by the following general formula: —NR ¹⁰ R ¹¹ (wherein R ¹⁰ and R ¹¹ are the same or different and represent a hydrogen atom or an alkyl group). Or a group represented by the following general formula: —NHSO ₂ R ¹² (in the formula, R ¹² represents a hydrogen atom, an alkyl group, an alkenyl group or an aryl group).

R ⁵ is a halogen atom, a carboxyl group,
Alternatively, it represents a sulfamoyl group. Further, the sulfamoyl group may have a substituent such as a carbonyl group or a carboxyl group.

R ⁶ represents an atomic group necessary for forming an aromatic ring, an aliphatic ring or a hetero ring by being condensed with the benzene ring having R ⁴ and R ⁵ described above, and these rings are the same as those described above. May have a substituent.

R ⁸ represents a hydrogen atom, an alkyl group or an aryl group, and the alkyl group or the aryl group may have the same substituents as described above. R ⁹ represents a phenylene group or a naphthylene group. These phenylene groups or naphthylene groups may also have the same substituents as described above.

Examples of the alkyl group include lower alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group and hexyl group. can give.

As the aryl group, for example, a phenyl group,
Examples thereof include a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group and a phenanthryl group. As the halogen atom, chlorine atom, bromine atom, iodine atom,
Fluorine atoms are included.

In R ⁶ , the atomic group necessary for forming an aliphatic ring by condensing with a benzene ring having R ⁴ and R ⁵ is, for example, a methylene group, an ethylene group, a propylene group or a butylene group. And an alkylene group having 1 to 4 carbon atoms.

Further, in R ⁶ , the atomic group necessary for forming a heterocycle by being condensed with the benzene ring having R ⁴ and R ⁵ is, for example, a benzofuranyl group, a benzothiophenyl group, a bezoxazolyl group, a benzothiazolyl group. 1H-indadoryl group, chromenyl group, chromanyl group, isochromanyl group, dibenzofuranyl group, carbazolyl group, xanthenyl group, acridinyl group, phenanthridinyl group, phenazinyl group, phenoxazinyl group, thianthrenyl group and the like.

The aromatic heterocyclic group formed by condensing the benzene ring having R ⁴ and R ⁵ with R ⁶ is, for example, a thienyl group, a furyl group, a pyrrolyl group, an oxazolyl group, an isoxazolyl group or a thiazolyl group. , Isothiazolyl group, imidazolyl group, pyrazolyl group, triazolyl group, tetrazolyl group, pyridyl group and thiazolyl group. Further, it may be a heterocyclic group condensed with an aromatic ring (for example, a benzofuranyl group, a benzimidazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinolyl group).

Specific examples of the coupler residue A having an acceptor property represented by the above general formulas (a) to (f) include:
The groups represented by C1 to C4 having the following strong acceptor properties and D1 to D having the extremely strong acceptor properties
The group represented by 3 can be mentioned.

[0030]

[Chemical 6]

The azo compound of the present invention represented by the above general formula (I) can be synthesized by various methods via the diazonium salt represented by the following general formula (IV) as an intermediate.

[0032]

[Chemical 7]

[Wherein X is a hydrohalic acid such as hydrochloric acid,
It shows anions of borofluoric acid, hydrobromic acid, sulfuric acid, nitric acid, perchloric acid and other acids.] For example, it can be easily produced by the method described below.

0.002 mol of tetrazonium difluoroborate represented by the formula (IV) and 0.002 mol of the coupler represented by the formula (III) were dissolved in 100 ml of N, N-dimethylformamide, and sodium acetate 0 .002m
ol dissolved in 5 ml of water is added dropwise over 5 minutes while maintaining the liquid temperature at 17 ° C to 21 ° C. Then, after stirring for 3 hours, 0.002 mol of a coupler represented by HA [A is a coupler residue in the general formula (I)] was added, and 0.002 mol of sodium acetate was dissolved in 5 ml of water. Dropwise as before and then stir for an additional 3 hours.

The precipitate formed is filtered, washed 5 times with 200 ml of N, N-dimethylformamide and then 20 times of water.
The azo compound of the present invention can be obtained by washing with 0 ml three times and then drying under reduced pressure.

In the electrophotographic photosensitive member of the present invention, the above-mentioned azo compounds can be used alone as a charge generating material, or can be used in combination with other conventionally known charge generating materials.

Other charge generating materials include, for example, amorphous silicon, pyrylium salt, anthanthrone pigment, phthalocyanine pigment, indigo pigment, triphenylmethane pigment, slene pigment, toluidine pigment,
Examples thereof include pyrazoline pigments, perylene pigments, quinacridone pigments and the like.

These charge generating materials are used alone or in combination of two or more so as to have an absorption wavelength region in a desired region. The constitution of the present invention can be applied to both so-called single-layer type and laminated type electrophotographic photoreceptors.

In order to obtain a single-layer type photoreceptor, a photosensitive layer containing an azo compound represented by the general formula (I), which is a charge generating material, a charge transporting material, a binder resin and the like is used. It may be formed on the conductive substrate by means such as coating.

In order to obtain a laminated type photoreceptor, a charge generating layer containing the above-mentioned azo compound as a charge generating material is formed on a conductive substrate by means of coating or the like, and this charge generating layer is formed. A charge transport layer containing a charge transport material and a binder resin may be formed thereover. On the contrary to the above, a charge transport layer similar to the above is formed on a conductive substrate, and then a charge generating layer containing the azo compound as a charge generating material is formed by means of coating or the like. Good. further,
The charge generation layer may be formed by dispersing a charge generation material and a charge transport material in a binder resin and applying the dispersion material.

As the charge-transporting material, conventionally known materials can be used, for example, oxadiazole compounds such as 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole. , Styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenyl Nitrogen-containing cyclic compounds such as amine compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, condensed polycyclic compounds can give.

These charge transport materials may be used alone or in combination of two or more. When a charge transporting material having film-forming property such as polyvinylcarbazole is used,
The binder resin is not always necessary.

Various resins can be used as the binder resin used in the above-mentioned single-layer type or laminated type photoreceptors, for example, styrene-based polymers, styrene-butadiene copolymers, styrene-polymers. Acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic polymer, styrene-acrylic copolymer, polyethylene, ethylene vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate Thermoplastic resin such as copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, epoxy resin, phenol resin, Urea resin, Min resin, other crosslinking thermosetting resin, further epoxy acrylates, urethane - various polymers, such as photo-curable resin such as acrylate.

These binder resins may be used alone or in admixture of two or more. A solvent is used when the charge generation layer and the charge transport layer are formed by a coating method or the like. As this solvent, various organic solvents can be used, for example, alcohols such as methanol, ethanol, isopropanol and butanol, aliphatic hydrocarbons such as n-hexane, octane and cyclohexane,
Benzene, toluene, aromatic hydrocarbons such as xylene, dichloromethane, dichloroethane, carbon tetrachloride, halogenated hydrocarbons such as chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran, ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, Examples thereof include ketones such as cyclohexanone, esters such as ethyl acetate and methyl acetate, and various solvents such as dimethylformaldehyde, dimethylformamide and dimethylsulfoxide.

These solvents may be used either individually or in combination of two or more. In addition, in order to improve the sensitivity of the charge generating layer, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used together with the charge generating material. Further, in order to improve the dispersibility of the charge transport material or the charge generating material, the dyeing property, etc., a surfactant, a leveling agent, etc. may be used.

As the conductive base material, various conductive materials can be used. For example, simple metals such as aluminum, copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass,
Examples thereof include a plastic material obtained by vapor deposition or laminating of the above metal, glass coated with aluminum iodide, tin oxide, indium oxide and the like.

The conductive base material may be in the form of a sheet or a drum, as long as the base material itself is conductive or the surface of the base material is conductive. As the base material, a base material having a sufficient mechanical strength when used is preferable.

The organic photosensitive layers of single-layer type and laminated type each include
A sensitizer, a fluorene compound, an antioxidant, a deterioration inhibitor such as an ultraviolet absorber, and an additive such as a plasticizer may be contained.

The amount of the charge transport material added to the single-layer type photosensitive layer is suitably 40 to 200 parts by weight, preferably 50 to 100 parts by weight, based on 100 parts by weight of the binder resin. Further, the addition amount of the charge transport material in the laminated charge transport layer is 10 to 100 parts by weight of the binder resin.
Suitably 500 parts by weight, preferably 25 to 200 parts by weight.

The amount of the charge generating material added to the single-layer type photosensitive layer is 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the binder. is there. Further, the addition amount of the charge generation material in the laminated charge generation layer is 5 to 5 parts by weight with respect to 100 parts by weight of the binder resin.
Appropriately is 00 parts by weight, preferably 10 to 300 parts by weight.

The thickness of the photosensitive layer formed is preferably about 5 to 100 μm, particularly about 10 to 50 μm in the case of a single layer type. On the other hand, in the case of a laminated type, the thickness of the charge generation layer is about 0.01 to 5 μm, preferably 0.1 to 5 μm.
About 3 μm, the thickness of the charge transport layer is about 2 to 100 μm,
It is preferably about 5 to 50 μm.

Further, in the case of a single-layer type electrophotographic photoreceptor, it is between the base material and the photosensitive layer, and in the laminated type electrophotographic photoreceptor, the base material and the charge generation layer. Between the base material and the charge transport layer, and between the charge generation layer and the charge transport layer, a barrier layer may be formed to the extent that the characteristics of the photoreceptor are not impaired. May have a protective layer formed thereon.

When the charge generation layer and the charge transport layer are formed by a coating method, the charge generation material and the binder resin may be formed by a known method such as roll mill, ball mill, attritor, paint shaker or ultrasonic wave. It may be prepared by dispersing and mixing using a disperser or the like, and applying and drying this by a known means. As described above, the charge generation layer may be formed by depositing the above charge generation material.

[0054]

The present invention will be described in detail below with reference to examples. As Examples 1 to 7 the charge generating material, (and A is a coupler residue, introduction position and the type of R ¹ are specifically described in Table 1) The azo compound represented by the general formula (I) the Using the following procedures, single-layer type and laminated type photoreceptors were prepared.

(Production of Single Layer Type Photoreceptor) 8 weight of bisazo compound as charge generating material and 3,3'-dimethyl-N, N, N ', N'-tetrakis-4- as charge transporting material. Methylphenyl- (1,1'-biphenyl)-
100 parts by weight of 4,4′-diamine and 100 parts by weight of a polyester resin as a binder resin are mixed and dispersed with a predetermined amount of tetrahydrofuran by using a ball mill,
A single layer type photosensitive layer coating solution was prepared.

This coating solution was prepared by applying a diameter of 80 mm and a length of 350 mm.
Drum type positive charging type electrophotographic photoconductor having a single-layer type photosensitive layer having a film thickness of 24 μm, which is applied on the surface of the aluminum base tube by a dipping method and then dried by heating at 100 ° C. for 30 minutes in a dark place. The body was made.

(Preparation of Laminated Photoreceptor) 100 parts by weight of polyvinyl butyral as a binder resin, 100 parts by weight of a bisazo compound as a charge generating material, and a predetermined amount of tetrahydrofuran were charged in a ball mill and mixed with stirring for 24 hours. Then, a charge generation layer coating liquid was prepared.

This coating solution was prepared by applying a diameter of 80 mm and a length of 350 mm.
After being applied on the surface of the aluminum base tube by the dipping method, it was dried in a dark place with hot air at 110 ° C. for 30 minutes to be cured to form a charge generation layer having a thickness of 0.5 μm.

Next, 100 parts by weight of polycarbonate as a binder resin and 3,3'-dimethyl-N, N, N ', N'-tetrakis-4-methylphenyl- (1,1) as a charge transport material. 100 parts by weight of'-biphenyl) -4,4'-diamine and a predetermined amount of toluene were mixed by stirring with a homomixer to prepare a charge transport layer coating solution.

This coating solution was applied onto the charge generation layer previously formed on the surface of the raw tube by the dipping method, and the coating was performed at 90 ° C. for 30 minutes.
A drum type negative charging type electrophotographic photoreceptor having a laminated type photosensitive layer was formed by forming a charge transport layer having a film thickness of about 20 μm by drying with hot air for a minute.

Comparative Examples 1 to 5 In the same manner as in Example 1 except that the bisazo type compound represented by the following general formula (V) was used as the charge generating material, single-layer type and laminated type photosensitive materials were used. The body was made. Specific examples of the coupler residue B include the following E
The groups represented by 1 to E5 are listed, and the groups used are shown in Table 2.

[0062]

[Chemical 8]

(In the formula, B represents a coupler residue.)

[0064]

[Chemical 9]

Comparative Examples 6 to 8 Single layer type and laminated type photosensitive materials were prepared in the same manner as in Example 1 except that a bisazo compound represented by the following general formula (Ib) was used as the charge generating material. The body was made.
Specific examples of the coupler residue C include the groups represented by E3, E5, and E6 below, and the groups used are shown in Table 2.

[0066]

[Chemical 10]

(In the formula, C represents a coupler residue.)

[0068]

[Chemical 11]

The following tests were carried out on the electrophotographic photosensitive members of the above Examples and Comparative Examples to evaluate their characteristics. Measurement of Initial Surface Potential Each electrophotographic photosensitive member is loaded in an electrostatic copying tester (Gentec Cynthia 30M, trade name, manufactured by Gentech), and the surface thereof is positively or negatively charged to obtain an initial surface potential Vs. .p. (V) was measured.

Measurement of Half-Exposure Amount and Residual Potential The electrophotographic photosensitive member charged in the above-mentioned measurement of the initial surface potential was measured at an exposure intensity of 10 lux by using a halogen lamp as an exposure light source of an electrostatic copying tester. Exposure under the conditions,
The half-exposure amount E1 / 2 (lux.sec) was calculated by obtaining the time until the surface potential became 1/2.

The surface potential was measured 0.5 seconds after the start of the exposure, and the residual potential V1r.p. (V) was measured. Measurement of Light Stability The electrophotographic photosensitive member was loaded in an electrostatic copying machine (model number DC-111 manufactured by Mita Kogyo Co., Ltd.) to continuously copy 1000 sheets, and then repeatedly exposed in the same manner as above. After that, the residual potential V2r.p. (V) was measured. Then, the residual potential V
The difference ΔVr.p. (V) between 1r.p. and V2r.p. was obtained.

The above results are shown in Tables 1 and 2.

[0073]

[Table 1]

[0074]

[Table 2]

From the results of Tables 1 and 2 above, the electrophotographic photoreceptors of Examples 1 to 7 having the constitution of the present invention are of single-layer type or laminated type as compared with the electrophotographic photoreceptors of Comparative Examples. Also, it is found that they have high sensitivity and excellent light stability.

[0076]

INDUSTRIAL APPLICABILITY As described above, the electrophotographic photoreceptor of the present invention is provided with a photosensitive layer containing a specific azo compound having high sensitivity and photostability, and therefore has high sensitivity and It has excellent durability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Mizuta 1-2-2 Tamazo, Chuo-ku, Osaka-shi, Osaka Within Mita Kogyo Co., Ltd. (72) Inventor Ikuhiko Kawahara 1-2-chome, Chuzo-ku, Osaka-shi, Osaka No. 28 Mita Industry Co., Ltd.

Claims (1)

[Claims] 1. A photoconductor comprising a conductive layer and a photosensitive layer containing an azo compound represented by the following general formula (I). [Chemical 1] [Wherein R ¹ is a hydrogen atom, a halogen atom, an alkyl group,
Alkoxy group, aryl group, amino group, cyano group, nitro group, sulfoxide group, A represents a coupler residue having an acceptor property]