JPH0445165A - Azo-based compound and photoreceptor for electrophotography using the same compound - Google Patents

Abstract

NEW MATERIAL:Compounds of formula I (A is coupler residue). EXAMPLE:A compound of formula II. USE:A charge-producing material in a photoreceptor for electrophotography. PREPARATION:A diamine of formula III is diazotized to obtain its tetrazonium salt of formula IV and a coupling reaction is then carried out between the resultant tetrazonium salt and a coupler in an organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an azo compound suitable as a charge generating material in an electrophotographic photoreceptor and an electrophotographic photoreceptor using the same.

<Problems to be solved by conventional technology and inventions> In recent years,
2. Description of the Related Art Organic photoreceptors are widely used as electrophotographic photoreceptors in image forming apparatuses such as copying machines because of their excellent processability and economic efficiency, and their large degree of freedom in functional design.

Further, when forming a copy image using an electrophotographic photoreceptor, the Carlson process is widely used. The Carlson process consists of a charging process in which a photoreceptor is uniformly charged by corona discharge, an exposure process in which an original image is exposed to the charged photoreceptor to form an electrostatic latent image corresponding to the original image, and an electrostatic latent image is formed in the electrostatic latent image. A development process in which a toner image is formed by developing with a developer containing toner, a transfer process in which the toner image is transferred to a base material such as paper, a fixing process in which the toner image transferred to the base material is fixed, and a transfer process. After the process, a cleaning process is included to remove toner remaining on the photoreceptor. In order to form high-quality images in this Carlson process, the electrophotographic photoreceptor is required to have excellent charging characteristics and photosensitivity characteristics, and to have a low residual potential after exposure.

Inorganic photoconductors such as selenium and cadmium sulfide have heretofore been known as electrophotographic photoreceptor materials, but these have the drawbacks of being toxic and having high production costs.

Therefore, so-called organic electrophotographic photoreceptors using various organic substances in place of these inorganic substances have been proposed. Such organic electrophotographic photoreceptors usually have a photosensitive layer made of a charge-generating material that generates charges upon exposure to light, and a charge-transporting material that has a function of transporting the generated charges.

In order to satisfy various conditions desired for such an organic electrophotographic photoreceptor, it is necessary to appropriately select the charge generating material and the charge transporting material.

Among these, charge-generating materials include organic photoconductive polymers such as polyvinylcarbazole, low-molecular organic photoconductors such as hydrazone compounds, phthalocyanine compounds, perylene compounds, quinacridone compounds, anthanthrone compounds, azo compounds, etc. Many compounds have been proposed. For example, as an azo compound, JP-A-47-37
The one disclosed in Japanese Patent No. 543 is known.

However, many of the conventional charge-generating materials mentioned above have a narrow photosensitive wavelength range or have strong absorption in the near-infrared region.
It does not have photosensitive wavelength characteristics over the entire visible light region.

For this reason, electrophotographic photoreceptors using the above-mentioned conventional charge-generating materials have problems in that it is difficult to faithfully reproduce color originals depending on the absorption wavelength characteristics of the photoreceptor, and the overall sensitivity is insufficient. .

In particular, with conventional azo compounds used as charge-generating materials, the photosensitive characteristics of the photoreceptor change due to repeated use over a long period of time.
Few of them have been put into practical use because they lack sufficient durability and have reduced sensitivity.

The present invention has been made in view of the above problems, and the present invention has been made to provide an azo compound that has excellent photosensitive properties and has stable sensitivity to light even when used repeatedly over a long period of time, and an azo compound that has excellent photosensitivity and stable sensitivity to light even when used repeatedly over a long period of time. The object of the present invention is to provide an electrophotographic photoreceptor using the present invention.

<Means and effects for solving the problems> The azo compound of the present invention is a photosensitive compound containing the azo compound of the present invention. The layer is provided on a conductive substrate to obtain an electrophotographic photoreceptor.

Since the electrophotographic photoreceptor of the present invention contains the above-mentioned azo compound in the photosensitive layer, the electrophotographic photoreceptor of the present invention can be used in the visible light region, particularly from 450 to 600 nm.
It has high sensitivity in the visible range and prevents surface potential from decreasing due to repeated use. Furthermore, it has stable sensitivity even when exposed to light for a long time or at high temperatures, and has excellent photostability.

The following may be the reason why the azo compound of the present invention has such high durability and stable sensitivity. That is, in the azo compound of the present invention, the π conjugation is spread throughout the central structure, which promotes planarization of the molecular structure and strengthens the intermolecular interaction due to the overlap between molecules.

Further, the coupler residue A in the present invention can be composed of various coupler components, such as the following coupler residues (a) to (g).

R6 In the above coupler residue, R1 is a hydroxyl group, (wherein R7 and R8 are the same or different and represent a hydrogen atom or an alkyl group), or a group: -NH3O2R9 (wherein, R9 is a hydrogen atom, an alkyl group, represents an alkenyl group or an aryl group).

R2 represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, a sulfamoyl group, or an aryl group, and the alkyl group or alkoxy group is a halogen atom, a phenyl group, a naphthyl group, a nitro group, It may have a substituent such as a cyano group. In addition, carbamoyl group or sulfamoyl group is a halogen atom, phenyl group, naphthyl group,
It may have a substituent such as an alkyl group, alkenyl group, carbonyl group, or carboxyl group.

R3 represents an atomic group necessary to form an aromatic ring, aliphatic ring or heterocycle by condensing with the benzene ring having R1 and R2, and these rings have the same substituents as above. Good too.

R4 represents a hydrogen atom, an amino group, an N-substituted amino group, an alkyl group, an alkenyl group, a hydroxy group, a carbamoyl group, a carboxyl group, or an alkoxycarbonyl group, and the alkyl group, alkenyl group, and carbamoyl group have the same substituents as above. may have.

R5 represents a hydrogen atom, an alkyl group, or an aryl group, and the alkyl group or aryl group may have the same substituent as above.

R6 represents a phenylene group or a naphthylene group.

These phenylene groups or naphthylene groups may also have the same substituents as mentioned above.

The alkyl group includes methyl, ethyl, propyl,
Examples include alkyl groups having 1 to 6 carbon atoms such as isopropyl, butyl, isobutyl, tert-butyl, pentyl, and hexyl.

Examples of the alkenyl group include vinyl, allyl,
2-butenyl, 3-butenyl, 1-methylallyl, 2-
Examples include alkenyl groups having 2 to 6 carbon atoms such as pentenyl and 2-hexenyl.

Examples of the halogen atoms include fluorine, chlorine, bromine, and iodine.

The alkoxy group includes methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, t
Examples include alkoxy groups having 1 to 6 carbon atoms such as ert-butoxy, pentyloxy, and hexyloxy.

Examples of the alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl,
isobutoxycarbonyl, benzyloxycarbonyl,
Examples include lower alkoxycarbonyl groups in which the alkoxy moiety has 1 to 6 carbon atoms, such as hexyloxycarbonyl.

In addition, in R3, the atomic group condensed with the benzene ring having R1 and R2 to form an aliphatic ring includes an alkylene group having 1 to 4 carbon atoms such as a methylene group, an ethylene group, a propylene group, a butylene group, etc. It will be done.

The heterocycle formed by condensing R3 with a benzene ring having R1 and R2 includes benzofuranyl, benzothiophenyl, indolyl, IH-indolyl, benzoxasilyl, benzothiazolyl, IH-imidazolyl, benzimidazolyl, chromenyl, chromanyl, Examples include isochromanyl, quinolinyl, isoquinolinyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, dibenzofuranyl, carbazolyl, xanthenyl, acridinyl, phenoxazinyl, phenazinyl, phenoxazinyl, thianthrenyl, and the like.

The azo compound of the present invention can be synthesized by various methods.

For example, as shown in the reaction formula below, it can be easily produced by diazotizing a diamine to form a tetrazonium salt, and then coupling this with a predetermined coupler in an organic solvent.

(Leaving space below) Reaction formula: (In the formula, A is the same as above, and X is an anion such as CD Br NO3-BF2-.) Diazotization is performed by adding sodium nitrite or nitrite to an acidic aqueous solution of diamine (1). Stir nitric acid at low temperature (usually -1
Tetrazonium salt (2
).

The coupling reaction involves N,N-dimethylformamide,
A predetermined amount of the coupler (3) is added to the pre-engineered tetrazonium salt (2) in an organic solvent such as dimethyl sulfoxide and allowed to react.

The compounds of the present invention can be used alone or in combination of two or more. It can also be used in combination with other conventionally known charge generating materials. Examples of the charge generating material include selenium, selenium-tellurium, amorphous silicon, pyrylium salts, conventionally known disazo compounds, anthanthrone compounds, phthalocyanine compounds, indigo compounds, triphenylmethane compounds, and slenium compounds. Examples include compounds, toluidine compounds, pyrazoline compounds, perylene compounds, and quinacridone compounds.

Further, the compound of the present invention can be applied to either a so-called single layer type or a laminated type electrophotographic photoreceptor. In order to obtain a single-layer type electrophotographic photoreceptor, a photosensitive layer containing the azo compound of the present invention as a charge generating material, a charge transporting material, and a binder resin is formed on a conductive substrate by means such as coating. good.

In order to make a laminated electrophotographic photoreceptor, a conductive base layer,
A charge generation layer containing the above azo compound may be formed by means such as coating, and a charge transport layer containing a charge transport material and a binder resin may be formed on this charge generation layer. Alternatively, a charge transport layer may be formed on the conductive substrate, and then a charge generation layer containing the charge generation material may be formed by means such as coating.

As the charge transport material, conventionally known materials can be used, such as oxadiazole compounds such as 2,5-di(4-dimethylaminophenyl)-1,3,4-oxadiazole, 9 (4-diethylaminostyryl)
Styryl compounds such as anthracene, carbazole compounds such as polyvinylcarbazole, 1-phenyl-3-
Nitrogen-containing compounds such as pyrazoline compounds such as (p-dimethylaminophenyl)pyrazoline, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, etc. Examples include cyclic compounds, fused polycyclic compounds, and hydrazone compounds.

These charge transport materials may be used alone or in combination of two or more. Note that when using a charge transporting material having film-forming properties such as polyvinylcarbazole, a binder resin is not necessarily required.

Furthermore, various resins can be used as the binder resin in the photosensitive layer, charge generation layer, and charge transport layer, for example,
Styrenic polymers, acrylic polymers, styrene-acrylic copolymers, polyethylene, ethylene-vinyl acetate copolymers, chlorinated polyethylene, polypropylene, olefin polymers such as ionomers, polyvinyl chloride, vinyl chloride-acetic acid Vinyl copolymer, polyester, alkyd resin, polyamide, polyurethane, epoxy resin,
Polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin,
Examples include various polymers such as polyvinyl butyral resin, polyether resin, phenol resin, and photocurable resins such as urethane resin, IJ resin, and epoxy acrylate. These binder resins may be used alone or in combination of two or more.

Further, when forming the charge generation layer and the charge transport layer by coating means, a solvent is used. As the above-mentioned solvent, various organic solvents can be used, including alcohols such as methanol, ethanol, isopropanol, butanol, aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane, benzene, toluene, xylene, etc. Aromatic hydrocarbons, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclohexanone Various solvents are exemplified, such as ketones such as ethyl acetate, esters such as ethyl acetate and methyl acetate, dimethylformamide, and methyl sulfoxide, which can be used singly or in combination of two or more.

Furthermore, in order to improve the sensitivity of the charge generation layer, for example,
Conventionally known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used together with the charge generating material. Furthermore, in order to improve the dispersibility, coating properties, etc. of the charge generating material, a surfactant, a leveling agent, etc. may be used in combination.

As the conductive base material, various conductive materials can be used, such as aluminum, copper, tin, platinum, gold,
Single metals such as silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, plastic materials vapor-deposited or laminated with the above metals, coated with aluminum iodide, tin oxide, indium oxide, etc. An example of this is glass. The above-mentioned conductive base material may be in the form of a sheet or a drum, and either the base material itself is conductive, or the surface of the base material is conductive, and has sufficient mechanical strength when used. Something is preferable.

The charge generating material and the binder resin in the laminated charge generating layer can be used in various ratios, but the charge generating material is preferably 5 to 500 parts by weight, particularly, based on 100 parts by weight of the binder resin. It is preferable to use 10 to 250 parts by weight.

Further, it is preferable that the charge generation layer is formed to have an appropriate thickness, preferably about 0.01 to 5 .mu.m, particularly about 0.1 to 3 .mu.m.

The charge transport material and binder resin in the laminated charge transport layer can be used in various ratios as long as they do not inhibit charge transport, or can be used in a manner that allows the charges generated in the charge generation layer by light irradiation to be easily transported. 10 to 500 parts by weight, particularly 25 parts by weight, of the charge transport material per 100 parts by weight of the binder resin.
~200 parts by weight is preferred.

Further, the charge transport layer has a thickness of 2 to 100 μm, particularly 5 to 30 μm.
It is preferable to form the film with a thickness of approximately μm.

In order to form the charge generation layer and the charge transport layer by coating, the charge generation material and the binder resin are coated using a conventionally known method such as a roll mill, ball mill, attritor, paint shaker, or ultrasonic disperser. What is necessary is just to apply|coat with a conventionally well-known coating means, and just to dry. Note that, as described above, the charge generation layer may be formed by vapor depositing the charge generation material.

In addition, to form a single-layer electrophotographic photoreceptor, a photosensitive layer containing the compound of the present invention as a charge-generating material, a charge-transporting material, a binder resin, etc. may be formed into a charge-generating layer or a charge-transporting layer. It may be formed on the conductive base material by the same method as in the case of the above.

The amount of the charge transport material added in the single-layer 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. Also,
The amount of the charge generating material added in the single-layer type photosensitive layer is suitably 2 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the combined weight.

The single layer type photosensitive layer has a thickness of 10 to 50 μm, especially 15 to 2 μm.
It is preferable that the film be formed to have a thickness of about 5 mm.

In a single-layer electrophotographic photoreceptor, there is a layer between the base material and the photosensitive layer, and in a laminated electrophotographic photoreceptor, the conductive base material and the charge generation layer or A barrier layer may be formed between the charge transport layer and between the charge generation layer and the charge transport layer as long as it does not impede the characteristics of the photoreceptor, and a protective layer may be formed on the surface of the photoreceptor. You can leave it there.

<Examples> Hereinafter, the azo compound of the present invention and an electrophotographic photoreceptor using the same will be described in more detail based on Examples and Comparative Examples.

Example 1 Add 3° (0°23 mol) of a diamine compound represented by the following formula (A) to 75 xi of 10% hydrochloric acid, stir while cooling in an ice water bath, and bring the liquid temperature to -1°C. I kept it. Next, 3°54g of sodium nitrite (
0,051 mol) to 10 mol of water? j' i: The dissolved material was added dropwise over 30 minutes while maintaining the liquid temperature at -2 to 1°C, and after the completion of the dropwise addition, the solution was stirred for 1 hour and then left to cool. And this is 42% hydrogen borofluoride 201! was added, the formed crystals were filtered, washed with ethanol and dried,
Obtained 5.82 g of tetrazonium difluoroborate (
Yield 75.4%).

Then, the obtained tetrazonium difluoroborate 0
．． 67g (0,002 mol) and 1°6g (0°004 mol) of the coupler represented by the following formula (): 1001! of N,N-dimethylformamide. A solution of 0.35 g (0,0043 mol) of sodium acetate dissolved in 5 yl of water was added dropwise thereto over 5 minutes while maintaining the temperature at 17 to 21°C. Next, after stirring for 3 hours, the formed precipitate was filtered and washed five times with N, N-';methylformamyl"2C3011. After washing twice with water, it was dried under reduced pressure to dissolve disazo. Compound 1.
17 g (yield 85.4%) was obtained.

The obtained disazo compound was subjected to elemental analysis, and it was confirmed that this compound was represented by the following formula (C).

Elemental analysis value: Calculated value as C40H26N 606 (
%) C: 69.94 H: 3.82 N
: 12.23 Actual value (%) C: 70.31 H: 3.71 N
: 12.12 Example 2 An azo compound was obtained in the same manner as in Example 1 except that p-cresol was used as the coupler.

Elemental analysis value: Calculated value as C20H2S N404 (
%) C: 63.83 H: 4.29 N: 14
．． 1119 Actual value (%) C: 64.01 H: 4.12 N
: 14.77 Example 3 An azo compound was obtained in the same manner as in Example 1 except that 4-hydroxyindoline was used as the coupler.

Elemental analysis value: C2゜I (calculated value as +aNs04 (
%) C: Eil, 39 H: 4.22 N: 1
9.52 Actual value (%) C: 61.48 H: 4.37 N
・19.36 Example 4 Except for using N-methylaniline as the coupler,
An azo compound was obtained in the same manner as in Example 1.

Elemental analysis value: Calculated value (%) as C20H2S Ns 02 C: 64. J, 6 H: 4.85 N: 2
2.45 Actual value (%) C: 64.13 H: 4.98 N
: 22.27 Example 5 An azo compound was obtained in the same manner as in Example 1 except that 1-methyl-5-hydroxypyrazole was used as the coupler.

Elemental analysis value 'C14HI3 Calculated value as N804 (
%) C: 47.20 H: 3°39 N: 31
．． 45 Actual value (%) C: 47.40 H: 3.28 N
: 31.58 Example 6 An azo compound was obtained in the same manner as in Example 1, except that the compound represented by the formula: was used as a coupler.

Elemental analysis value: Calculated value as C32H18Ns Os (
%) C: 62.54 H: 2.95 N: 13
．． 68 Actual value (%) C: Ei2.37 H: 3.04 N: 1
An azo compound was obtained in the same manner as in Example 1, except that the compound represented by 3.50 Example 7 was used as a coupler.

Elemental analysis value: Calculated value as C42H20N606 (%
) C: 71.59 H: 2.86 N: 11
．． 93 Actual value (%) C: 71.73 H: 2.69 N: 11
．． 85 Preparation of electrophotographic photoreceptor Preparation of single-layer electrophotographic photoreceptor 8 parts by weight of the azo compounds obtained in Examples 1 to 8 above as a charge generating material, 3゜3゛-dimethyl-N as a charge transport material, N N-N--tetrakis-4-methylphenyl (1,1-biphenyl) 4.4'-diamine 10
0 parts by weight, 100 parts by weight of poly-(4,4'-cyclohexylidene diphenyl) carbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd., Polycarbonate 2200) as a binder resin, and a predetermined amount of tetrahydrofuran were combined into an ultrasonic disperser. The mixture was mixed and dispersed to prepare a coating solution for a single-layer photosensitive layer. After applying this coating liquid onto the aluminum tube, 1 coat in a dark place.
The resulting product was heated and dried at 00° C. for 30 minutes to produce a drum-shaped electrophotographic photoreceptor having a single-layer photosensitive layer with a thickness of 24 μm.

Preparation of laminated electrophotographic photoreceptor Polyvinyl butyral (manufactured by Block Chemical Co., Ltd.,
In a ball mill, 100 parts by weight of the azo compound obtained in Examples 1 to 8 as a charge generating material and a predetermined amount of tetrahydrofuran were charged, and the mixture was stirred and mixed for 24 hours to form a charge generating layer. A charge generation layer having a thickness of 0.5 .mu.m was formed by applying the prepared coating solution onto an aluminum tube by dipping and drying with hot air at 110.degree. C. for 30 minutes to harden the coating solution.

Next, 100 parts by weight of polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: Niepiron) was added as a binder resin, and 3.3'-dimethyl-N, N, N-, N- was added as a charge transport layer.
A charge transport layer coating liquid was prepared by stirring and mixing 100 parts by weight of -tetrakis-4-methylphenyl-(1,1-biphenyl)-4,4-1 diamine and a predetermined amount of toluene using a homomixer. This coating solution was applied to the surface of the charge generation layer by a dipping method and dried with hot air at 90° C. for 30 minutes to form a charge transport layer having a thickness of 20 μm, thereby producing a laminated electrophotographic photoreceptor.

Comparative Example A single-layer type and A laminated electrophotographic photoreceptor was created.

(3) Evaluation of electrophotographic photoreceptor Measurement of initial surface potential V5p Each of the above-mentioned single-layer electrophotographic photoreceptors was loaded into an electrostatic copying tester (Dientic Cynthia 30M, manufactured by Gientic Co., Ltd.), and the surface was The surface potential Vsp (V) of each photoreceptor was measured after being negatively charged.

Half-reduction exposure amount E, /2 and residual potential 1. Measurement Each electrophotographic photoreceptor in the above charged state was exposed to light at an intensity of 101 L using a halogen lamp, which is the exposure light source of the electrostatic copying tester.
IX exposure, find the time until the surface potential Vsp (V) becomes 1/2, and calculate the half-reduction exposure amount El/2 (1ux
-sec) was calculated.

Further, the surface potential after 0.15 seconds had passed after the start of the exposure was defined as the residual potential V, p (V).

Table 1 shows the measurement results of the above electrophotographic properties.

(Left below) Table 1 As shown in Table 1, both the single-layer type and the laminated type photoreceptor using the azo compound of the present invention as a charge-generating material have a higher residual potential V than the comparative example. , P is very small,
It can be seen that it has excellent stability against light. Further, it can be seen that the half-decreased exposure amount El/□ is small, has stable high sensitivity, and has excellent repeatability, making it suitable as a charge-generating material.

<Effects of the Invention> As described above, the azo compound of the present invention has π conjugation spread throughout the central structure, has high sensitivity in the visible light region, and has excellent photostability. Moreover, it is easy to manufacture.

Furthermore, by using this azo compound, an electrophotographic photoreceptor with high sensitivity and excellent photostability and repeatability can be manufactured with high productivity and at low cost.

Claims (1)

[Claims] 1. An azo compound represented by the following general formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, A represents a coupler residue.) 2. An electrophotographic photoreceptor, characterized in that a photosensitive layer containing the azo compound according to claim 1 is provided on a conductive base material.