JPH0314340B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a hydrazone compound as a photoconductive substance in a layer formed on a conductive support. In conventional electrophotographic technology, inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors, but in recent years, organic photoconductive materials have been used in electrophotography. Many studies have been conducted on using it as a photoreceptor. Here, the basic properties required for an electrophotographic photoreceptor are (1) high chargeability due to corona discharge in the dark, and (2) high chargeability due to corona charging in the dark. (3) the charge dissipates rapidly upon irradiation with light; and (4) there is little residual charge after irradiation with light. Conventional inorganic electrophotographic photoreceptors such as selenium and cadmium sulfide meet the requirements for photoreceptors in terms of basic properties, but on the other hand, the stability and durability of photoreceptors over time are limited. There are problems in manufacturing, for example, it is difficult to form a film, and it has disadvantages such as high toxicity and undesirable from the viewpoint of safety and health. However, in view of these points, research on electrophotographic photoconductors made of organic substances has been actively conducted in recent years, and electrophotographic photoconductors using various organic substances have been proposed and put into practical use. Generally speaking, organic materials have better transparency, are lighter, have better film forming properties, and are easier to manufacture photoreceptors than inorganic materials. On the other hand, typical organic electrophotographic photoreceptors that have been proposed so far include polyvinylcarbazole and its derivatives, but these do not necessarily have sufficient film properties, flexibility, solubility, or adhesive properties. In addition, polyvinylcarbazole is sensitized with pyrylium salt dye (Special Publication No. 48-25658)
or sensitized with polyvinylcarbazole and 2,4,7-trinitrofluorenone (U.S. patent
Although there are some improved products such as 3484237), there are still not enough products that satisfy the basic properties, mechanical strength, and high durability that are required for a photoreceptor. do not have. As a result of research into photoconductive substances with high sensitivity and high durability, the present inventors found the following general formula ()
The present inventors have discovered that the hydrazone compound represented by the following formula is effective, leading to the present invention. In the above general formula (), the substituent R ₁ is an alkyl group that may have a substituent (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group,
Butyl group, isobutyl group, pentyl group, cyclohexyl group, chloromethyl group, bromomethyl group, chloroethyl group, cyanoethyl group, hydroxyethyl group, methoxyethyl group, phenoxyethyl group,
(methcarboxyethyl group, etc.), aralkyl group (e.g., benzyl group, β-phenethyl group, naphthylmethyl group, O, m, p-methylbenzyl group,
(O, m, p-chlorobenzyl group, O, a, p-methoxybenzyl group, 2,4-dimethylbenzyl group, 4-ethylbenzyl group, 2-pyridylmethyl group, 4-pyridylmethyl group, etc.), aryl group (For example, phenyl group, naphthyl group, o, m, p
-tolyl group, o, m, p-chlorophenyl group,
o, m, p-methoxyphenyl group, p-ethoxyphenyl group, p-phenoxyphenyl group, 2,4
-xylyl group, 2,4,6-trimethylphenyl group, p-biphenyl group, etc.) and methallyl group, and the substituent R ₂ is a hydrogen atom, a halogen atom, an alkyl group that may have a substituent ( For example, methyl group, ethyl group, propyl group, chloroethyl group, methoxymethyl group, ethoxyethyl group, phenoxyethyl group, etc.), alkoxy group (e.g.
methoxy group, ethoxy group, propoxy group, butoxy group, etc.), and substituent R ₃ is a hydrogen atom,
Alkyl groups that may have substituents (for example,
methyl group, ethyl group, propyl group, butyl group, chloromethyl group, methoxyethyl group, phenoxyethyl group, etc.), and aryl groups (e.g., phenyl group, naphthyl group, o, m, p-tolyl group, xylyl group, chlorophenyl group) group, methoxyphenyl group, etc.), and R ₄ and R ₅ represent an alkyl group that may have a substituent (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, chloroethyl group, methoxy ethyl group, phenoxyethyl group), aralkyl group (e.g. benzyl group, β-phenethyl group, naphthylmethyl group, o,
m, p-methylbenzyl group, o, m, p-chlorobenzyl group, o, m, p-methoxybenzyl group,
2,4-dimethylbenzyl group, 4-ethylbenzyl group, 2-pyridylmethyl group, 4-pyridylmethyl group, etc.), aryl group (e.g. phenyl group, 1
-naphthyl group, 2-thiphthyl group, O-methoxyphenyl group, p-ethoxyphenyl group, p-methylphenyl group, p-chlorophenyl group, etc.), alkenyl group (e.g. allyl group, methallyl group, 3-
butenyl group, cinnamyl group, etc.), alkynyl group (eg, propargyl group, etc.), and n represents 0 or 1. These hydrazone compounds represented by the general formula () can be produced by conventional methods. That is, or, (X in formula () represents a halogen atom) In method A, a ketone compound and N,N
A hydrazone compound (2) is obtained by heating the -disubstituted hydrazine compound in an alcoholic solvent, adding an acid as a catalyst if necessary. In addition, in Method B, a ketone compound and an N-monosubstituted hydrazine compound are heated and reacted in an alcoholic solvent to first produce a hydrazone compound (), and then this compound () and a halogenated alkyl compound are reacted with an alkali catalyst. A similar hydrazone compound () can also be obtained by the reaction below. As the solvent used in this case, general organic solvents can be used, such as aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene, tetrahydrofuran, dioxane,
Ethers such as isopropyl ether, aprotic solvents such as acetone, dimethylformamide, and dimethyl sulfoxide, and in some cases, protic solvents such as water, methanol, and ethanol can also be used. In addition, it is desirable to add an appropriate alkaline catalyst to this condensation reaction, and examples of alkaline catalysts include sodium hydroxide,
Examples include potassium hydroxide, sodium acetate, potassium carbonate, triethylamine, piperidine, and sodium methylate. Next, synthesis examples of specific compounds will be shown. Synthesis Example 1 Synthesis of 1-phenyl-1-benzylhydrazone of 4-(N-ethyl-N-methallyl)aminobenzaldehyde (Exemplary Compound 3). 2.0 g (0.01 mol) of 4-(N-ethyl-N-methallyl)aminobenzaldehyde, and 2.4 g (0.01 mol) of 1-phenyl-1-benzylhydrazine hydrochloride.
mol) and ethanol with 1.0 g of potassium acetate.
Using 10 ml as a solvent, heat and reflux for 1 hour. After cooling, take the solidified product, dissolve it in benzene again to remove insoluble matter, and dry it. The obtained crude product is recrystallized from a mixed solvent of ethyl acetate and methanol, with a melting point of 118.
1.8 g of light brown crystals of ~119°C are obtained. Synthesis example 2 4-(N-ethyl-N-methallyl)amino-2
-Synthesis of phenylhydrazone of methylbenzaldehyde and its p-methylbenzylation (Exemplary Compound 6). 4-(N-ethyl-N-methallyl)amino-2
- After heating and refluxing 11 g of methylbenzaldehyde and 5.4 g of phenylhydrazine in ethanol, the solvent is distilled off to obtain an oily hydrazone. Add 14g of this oil to 46ml of dimethyl sulfoxide.
and 5N-NaOH aqueous solution, and while stirring, p-
6.4 g of methylbenzyl chloride was added dropwise and the mixture was stirred at room temperature for 3 hours to precipitate. When this is recrystallized from ethyl acetate/methanol, it has a melting point of 91-
Obtain 10 g of pale yellow crystals at 93°C. Synthesis Example 3 Synthesis of 1,1-diphenylhydrazone of 4-dimethallylamino-2-methylbenzaldehyde (Exemplary Compound 12). 2.4 g (0.01 mol) of 4-dimethallylamino-2-methylbenzaldehyde and 2.4 g (0.01 mol) of 1,1-diphenylhydrazine hydrochloride were added with 1.0 g of potassium acetate and heated under reflux in 10 ml of ethanol for 1 hour. , crystallizes when cooled. Take this, dissolve it in ethyl acetate, add methanol and purify it to produce 2.8g of white crystals with a melting point of 91-92.5℃.
get. Synthesis Example 4 Synthesis of phenylhydrazone of 4-dimetallylamino-2-methylbenzaldehyde and metallylation thereof (Exemplary Compound 17). 12.2 g (0.05 mol) of 4-dimetallylamino-2-methylbenzaldehyde and 5.4 g (0.05 mol) of phenylhydrazine were heated under reflux in ethanol for 30 minutes, and then the ethanol was distilled off to obtain a solid substance. Washing with water gives 14.1 g of hydrazone compound. 3.33 g (0.01 mol) of this solid was mixed with 15 ml of dimethyl sulfoxide and 5N-
Dissolve in NaOH aqueous solution, dropwise add 1.0 g (0.01 mol) of methallyl chloride while stirring, and stir at room temperature for 2 hours to precipitate. This is taken, heated and dissolved in ethyl acetate, filtered, and then methanol is added to precipitate it. 1.4 g of crystals with a melting point of 84-85°C are obtained. Examples of hydrazone compounds corresponding to general formula () are as follows. The invention is not limited to these compounds. The electrophotographic photoreceptor of the present invention exhibits excellent performance by containing one or more of the above-mentioned compounds in the photosensitive layer. Various methods are known for using these hydrazone compounds as electrophotographic photoreceptors.
For example, a photosensitive material prepared by dissolving or dispersing the present hydrazone compound and a sensitizing dye in a binder, with the addition of a chemical sensitizer or an electron-withdrawing compound if necessary, on a conductive support. In the form of a laminated structure consisting of a carrier generating layer having extremely high charge carrier generating efficiency and a carrier transfer layer, the carrier generating layer is provided on a conductive support mainly consisting of a sensitizing dye or a pigment. In addition, there are photoreceptors in which the present hydrazone compound is dissolved or dispersed in a binder with the addition of a chemical sensitizer or an electron-withdrawing compound if necessary, and is provided as a carrier transport layer. It is possible to apply in either case. When producing a photoreceptor using the compound of the present invention, a polymer film can be formed on a support such as a metal plate, a metal cylinder, a conductive treated paper, or a conductive treated plastic film. It is applied using a solvent together with a binder to form a film. In this case, for the purpose of further improving the sensitivity or improving the mechanical strength, adhesion, and durability of the photoreceptor, a sensitizer or a substance that imparts plasticity to the polymer film-forming binder as described below is added. It is also possible to do so. Examples of the polymerizable film-forming binder include the following. Polystyrene resin, styrene-butadiene copolymer resin, polyvinyl acetal resin, diallyl phthalate resin, silicone resin, polysulfone resin, polycarbonate resin, acrylic resin, methacrylic resin, vinyl acetate resin, acetic acid-crotonic acid copolymer resin, poly These include phenylene oxide resin, polyester resin, alkyd resin, polyarylate resin, styrene-maleic anhydride half ester resin, phenol resin, petitral resin, alcohol-soluble nylon resin, popal resin, etc., and these can be used alone or as a copolymer. One type or a mixture of two or more types can be used. These binders are added in a weight ratio of 0.2 to 20 times, preferably 0.5 to 5 times, the weight of the organic photoconductor. If it is less than 0.5 times, there is a drawback that the organic photoconductor will be deposited on the surface of the photoreceptor, and if it is more than 5 times, the sensitivity will be significantly lowered. In some types of binders used in this case, the formed photosensitive layer may be inflexible and brittle, or may not be resistant to mechanical properties such as bending and compression. In order to improve these properties, it is also necessary to add a substance that imparts plasticity. These substances include phthalate esters, phosphate esters (e.g. dioctyl phthalate, dibutyl phthalate, tricresyl phosphate, etc.), epoxidized soybean oil,
Examples include nitrile rubber and chlorinated hydrocarbons, but the appropriate amount of these substances to be used as a binder is 0.1 to 20% by weight; if more than 20% is used, it will adversely affect the electrophotographic properties. Next, the sensitizing dyes added to the photosensitive layer include triphenylmethane dyes such as methyl violet, crystal violet, ethyl violet, night blue, and Victoria blue, erythrosine, rhodamine B, and rhodamine.
3B, Acridine Red B, etc., acridine dyes such as Acridine Orange 2G, Acridine Orange R, Frapeosin, etc., thiazine dyes such as methylene blue, methylene green, methyl violet, etc., Cabriblue, Examples include oxazine dyes such as Meldora Blue, other cyanine dyes, styryl dyes, pyrylium salts, and thiapyrylium salts. Photoconductive pigments that generate charge carriers with extremely high efficiency through light absorption in the photosensitive layer include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, perylene pigments such as perylene imide and perylene acid anhydride, There are azo pigments such as monoazo pigments, bisazo pigments, and trisazo pigments, as well as quinacridone pigments and anthraquinone pigments. Furthermore, inorganic photoconductive substances include selenium, selenium-tellurium alloys, cadmium sulfide, zinc oxide, and the like. In addition to the sensitizers listed above (spectral sensitizers), sensitizers (chemical sensitizers) are used to further increase sensitivity.
It is also possible to add. Examples of chemical sensitizers include p-chlorophenol, m-chlorophenol, p-nitrophenol, 4-chloro-m
-cresol, p-chlorobenzoylacetanilide, N,N'-diethylpalpituric acid, N,
N'-diethylthiopalpituric acid, 3-(β-oxyethyl)-2-phenylimino-thiazolidone, malonic acid dianilide, 3,3',5,5'-tetrachloromalonic acid dianilide, α-naphthol,
Examples include p-nitrobenzoic acid. Further, certain electron-withdrawing compounds can be added as sensitizers that combine with the hydrazone compound of the present invention to form a charge transfer complex and further increase the sensitizing effect. Examples of this substance include 1-chloroanthraquinone, 1-nitroanthraquinone, 2,3-dichloro-naphthoquinone, 3,3-dinitrobenzophenone, 4-nitrobenzalmalononitrile, phthalic anhydride, 3-(α-cyano -p-nitrobenzal) phthalide, 2,4,7-trinitrofluorenone, 1-methyl-4-nitrofluorenone,
Examples include 2,7-dinitro-3,6-dimethylfluorenone. In addition, antioxidants, ultraviolet absorbers, and the like may be added as additives to the photoreceptor, if necessary. The hydrazone compound of the present invention is dissolved or dispersed in an appropriate solvent together with the various additives mentioned above depending on the form of the photoreceptor, and the coating solution is applied onto the conductive support described above and dried. A photoreceptor is manufactured. Most organic solvents can be used as coating solvents, including aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene, chlorinated hydrocarbons such as chloroform, dichloroethane, and trichloroethylene, and ethers such as dioxane and tetrahydrofuran. ethyl acetate, butyl acetate,
A single or mixed solvent of two or more solvents such as esters such as methyl cellosolp acetate, alcohols, acetonitrile,
A solvent such as N,N-dimethylformamide or methyl ethyl ketone may be further added. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 Chlordiane blue represented by: and a polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) are mixed in a 2:1 weight ratio and dispersed in dichloroethane at a concentration of 5% by weight in a ball mill to prepare a liquid. This dispersion was applied onto an aluminum-coated polyester film as a support using an S-doctor (wire bar) to form a charge generation layer having a dry film thickness of about 0.1 μm. Next, the compound of the present invention (exemplary compound (2)) and polycarbonate resin (Iupilon N-6 manufactured by Mitsubishi Gas Chemical Co., Ltd.) at a weight ratio of 1:1 was dissolved in dichloroethane to a concentration of 10% by weight to prepare a solution and coated on the charge generation layer. death,
A photoreceptor having a charge transfer layer with a dry film thickness of about 20 μm was prepared. This photoreceptor was tested using an electrostatic recording paper tester (manufactured by Kawaguchi Denki).
As a result of measuring the electrophotographic characteristics with SP-428 type), -
With 6KV corona charging, the exposure amount is halved by 4.0 Lux.
It was hot in seconds. Examples 2 to 9 Photoreceptors were prepared using the following hydrazone compounds in the same manner as in Example 1, and the half-life exposure was measured. Next, the repetition characteristics of the photoreceptor were investigated using the same device. The characteristic value of repetition is the value obtained by dividing the potential after 1000 repetitions by the potential of the first repetition, and is expressed in %.

【table】

[Table] Example 10 A plate-making master photoreceptor was prepared using a grained and anodized printing aluminum plate as a support. Namely, chlordiane blue and styrene-maleic anhydride copolymer resin (acid value 150)
A dispersion liquid was prepared by mixing these at a weight ratio of 1:1 and kneading the mixture in a ball mill for 4 hours. This dispersion was applied onto the aluminum plate to form a charge generation layer having a thickness of about 0.2 microns. On the other hand, hydrazone compounds No. 4 (melting point 100°C) and No. 13 (melting point 128°) of the present invention,
Each was mixed with a styrene-acrylic acid copolymer resin (acid value 180) at a weight ratio of 1:1, and 10% by weight was added to a xylene-butanol (1:1) mixed solvent.
Two types of photoreceptors were prepared by preparing a solution in which the above-mentioned components were dissolved and coating the solution on the charge generation surface obtained above to form a charge transfer layer with a thickness of about 4 microns. In order to evaluate the photoreceptor thus obtained as a lithographic printing original plate, an image was reflectively printed using a plate-making camera, and wet development was performed. Next, the non-image area is clearly removed using an etching solution (i.e., a solution of 28 g of potassium hydroxide, 2 g of sodium hexametaphosphate, 35 g of benzyl alcohol, and 40 g of monoethanolamine with water to make a total volume of 1 part). I was able to obtain the original version. 2 more copies of this version
% phosphoric acid aqueous solution and a printing durability test using an offset printing machine, both Compounds Nos. 4 and 13 were able to print over 10,000 sheets with clear images.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a layer containing a hydrazone compound represented by the following general formula () on a conductive support. (In the formula, R ₁ is an alkyl group, an aralkyl group, an aryl group, which may have a substituent,
[Formula] represents a group, R ₂ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, or an alkoxy group, R ₃ represents a hydrogen atom,
represents an alkyl group or aryl group that may have a substituent, R ₄ and R ₅ represent an alkyl group, an aralkyl group, an aryl group, an alkenyl group, or an alkynyl group that may have a substituent, and n represents an integer of 0 or 1. )