JPH0314341B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor in which a layer formed on a conductive support contains a hydrazone compound represented by the following general formula (). It is related to.

(In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group that may have a substituent, or an alkoxy group, and R ₂ represents a hydrogen atom, an alkyl group that may have a substituent, or an aralkyl group. , represents an aryl group, R ₃ and R ₄ represent an alkyl group, an aralkyl group, or an aryl group which may have a substituent, and n represents an integer of 0 or 1.) In conventional electrophotographic technology Inorganic materials such as selenium, cadmium sulfide, and zinc oxide are widely used in the photosensitive layer of electrophotographic photoreceptors, but in recent years, much research has been conducted on using organic photoconductive materials as electrophotographic photoreceptors. ing.

Here, the basic properties required for an electrophotographic photoreceptor are (1) high chargeability due to corona charging in the dark, and (2) charge due to corona charging obtained there is high in the dark. (3) the charge quickly dissipates upon irradiation with light; and (4) there is little residual charge after irradiation with light.

Today, organic photoconductive materials are being replaced by inorganic photoconductive materials. Although it has advantages in terms of basic electrophotographic properties such as residual potential, it also has various disadvantages.

Many of the disadvantages are, for example, manufacturing difficulties and problems with regard to toxicity of the raw materials in terms of pollution or sanitary use. In the case of selenium, in addition to the difficult manufacturing conditions for the selenium vapor deposition film, it is weak in mechanical strength and tends to crystallize selenium on the surface of the photoreceptor, and in the case of cadmium sulfide, it is sensitive to temperature and humidity. Therefore, there is a problem of pollution caused by cadmium compounds. In addition, in the case of zinc oxide, there are problems with dispersion stability when dispersing zinc oxide particles in resin,
There are problems such as significant performance deterioration due to temperature and humidity.

On the other hand, compared to inorganic photoconductive materials, organic photoconductive materials can often use resins as binders and are easier to manufacture, whether in solution or dispersion form. It is easy and inexpensive. In addition, the photosensitive layer is highly flexible,
There are excellent advantages, such as the fact that photoreceptors with various functions can be easily obtained depending on the purpose of use of the photoreceptor, and photoreceptors can be designed in a variety of ways.

In view of these points, research and development of electrophotographic photoreceptors using organic photoconductors has recently become active, and electrophotographic photoreceptors using various organic photoconductors have been proposed and are not being commercially implemented. Some have even been put into practical use.

For example, organic photoconductors such as polyvinylcarbazole are sensitized by adding dyes such as pyrylium salt dyes (Japanese Patent Publication No. 48-25658), and electron-donating compounds (such as polyvinylcarbazole) and electron-accepting compounds ( 2,4,7-trinitrofluorenone, etc.) and sensitized by forming a charge transfer complex
10496), a functionally separated type in which the functions of carrier generation and carrier movement are separated into different substances (Japanese Patent Publication No. 105537, 1973), and a thiapyrylium salt dye (carrier generator) and a triphenylmethane compound ( A photoreceptor (Special Publication Act, 1973-
38430) can be cited as representative examples.

However, although these various proposals have been made, there is still not enough material that satisfies the basic properties, mechanical strength, durability, and preservability requirements listed above for a photoreceptor. It has not been done.

The present inventors conducted various studies to address these problems, and as a result, they were able to produce a photoreceptor containing the compound of the present invention.

In the hydrazone compound of the above general formula () according to the present invention, the substituent R ₁ is a hydrogen atom, a halogen atom (e.g. chloro, bromine, etc.), an alkyl group (e.g. methyl group, ethyl group, propyl group, etc.) or an alkoxy group ( For example, methoxy group,
ethoxy group, propoxy group, etc.), and the substituent R ₂ represents a hydrogen atom, an alkyl group (e.g., methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, etc.), an aralkyl group (e.g., benzyl group, etc.). group, β-phenylethyl group, naphthylmethyl group, etc.) or aryl group (e.g. phenyl group, naphthyl group, tolyl group, xylyl group, p-
methoxyphenyl group, etc.), and the substituent R ₃
and R ₄ may be the same or different and may be an alkyl group (e.g., methyl group, ethyl group, n-
propyl group, cyclohexyl group), aralkyl group (e.g. benzyl group, β-phenylethyl group, naphthylmethyl group, p-methylbenzyl group,
p-methoxybenzyl group, etc.) or an aryl group (e.g. phenyl group, naphthyl group, tolyl group, 2,4-dimethylphenyl group, p-methoxyphenyl group, etc.), and n is an integer of 0 or 1. represent

These hydrazone compounds represented by the general formula () can be produced by conventional methods. That is, A ketone compound () and a hydrazone compound () are placed in an alcoholic solvent, an acid is added as a catalyst if necessary, and the hydrazone compound () is obtained by heating.

Typical synthesis examples are described below.

Synthesis Example Compound (2) Add 2 g of potassium acetate to 3 g of piperonal and 4.4 g of 1,1-diphenylhydrazine hydrochloride,
Heat to reflux in ethanol for 1 hour. The precipitate is collected, washed with water, and then recrystallized from ethyl acetate to determine the melting point.
Obtain 4.5 g of white crystals of 137°.

The compounds of the present invention are obtained by such methods, and representative examples thereof are listed below, but the invention is not limited thereto.

The electrophotographic photoreceptor of the present invention has 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, the present hydrazone compound and a sensitizing dye, optionally with the addition of a chemical sensitizer or an electron-withdrawing compound, are dissolved or dispersed in a binder and then provided on a conductive support. photoreceptor, or
In the form of a laminated structure consisting of a carrier generation layer with extremely high charge carrier generation efficiency and a carrier transfer layer, the present hydrazone is applied onto the carrier generation layer which is provided mainly with a sensitizing dye or pigment on a conductive support. There are photoreceptors in which a carrier transport layer is provided with a compound dissolved or dispersed in a binder with the addition of a chemical sensitizer or an electron-withdrawing compound if necessary. can also be applied.

When producing a photoreceptor using the compound of the present invention, it is necessary to form a polymerizable film 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, in order to further improve the sensitivity or improve the mechanical strength, adhesiveness, and durability of the photoreceptor, a sensitizer or a substance that imparts plasticity to the polymerizable film-forming binder as described below may be added. It is also possible to add.

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 copolymer resin, styrene-maleic anhydride half ester resin, phenol resin, petitral resin, poval resin, etc. Alternatively, one type or a mixture of two or more types can be used as a copolymer. Further, 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, nitrile rubber, chlorinated hydrocarbons, etc. The amount of these substances used relative to the binder is 0.1 by weight.
~20% is appropriate; if more than 20% is used, electrophotographic properties will be adversely affected.

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, rhodamine 3B,
Zansen dyes represented by Acridine Red B, acridine dyes represented by Acridine Orange 2G, Acridine Orange R, Frapeosin, etc., thiazine dyes represented by Methylene Blue, Methylene Green, Methyl Violet, etc.
These include oxazine dyes such as Capri Blue and 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 materials 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'-diethylbarbituric acid, N,
N'-diethylthiobarbituric 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, 2,7-dinitro-3,6-dimethylfluorenone, etc. can give.

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, the coating solution is applied onto the conductive substrate mentioned above, and then 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 solvent or a mixture of two or more solvents such as esters such as methyl cellosolve 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 Pigments shown below 1 part by weight and 1 part by weight of polyarylate resin (U-100 manufactured by Unitika) are added with dichloroethane so that the solid content becomes 5% by weight, and dispersed using a Dyno Mill disperser to prepare a coating liquid. This dispersion was applied using a doctor onto a conductive support made of a polyester film laminated with aluminum foil. A charge generation layer with a dry film thickness of about 0.1μ was formed.

Next, the compound shown below which is the compound of the present invention 1 part by weight and 1.2 parts by weight of the polyarylate resin were dissolved in 10 parts by weight of monochlorobenzene, and this solution was applied onto the charge generation layer prepared above using a doctor. A charge transfer layer with a dry film thickness of about 17 μm was formed.

The electrophotographic properties of the thus obtained photoreceptor were evaluated using an electrostatic recording paper testing device (Model SP-428 manufactured by Kawaguchi Denki). As a result, when the corona charge was measured at -6KV, the dark decay rate after 10 seconds with respect to the initial charge amount was
93%, and the half-life exposure to white light (10 lux) was 12.5 lux·sec.

Example 2 Using an anodized aluminum plate (thickness 100μ) as a support, 1 part by weight of the pigment used in Example 1 as a charge generating agent and a styrene-maleic anhydride copolymer resin (acid value 150) were added. ) was dispersed in a mixed solvent of toluene and butyl acetate (1:1) at a concentration of 5% by weight using a Dyno Mill dispersion machine, and then applied using an S-doctor (wire bar) to form a dry film with a dry film thickness of approximately 0.2μ. A charge generation layer was formed.

The charge transfer layer was prepared by dissolving 1 part by weight of Exemplary Compound (2) and 1.5 parts by weight of styrene-acrylic acid copolymer resin (acid value 180) in monochlorobenzene to a concentration of 10% by weight. Coated on top of the generation layer. The dry film thickness was approximately 6μ.

The exposure amount for half the sensitivity of this photoreceptor was 9 lux·sec.

In addition, in order to check the effectiveness of this photosensitive plate as a plate-making master, we used an electrophotographic plate-making machine EP manufactured by Mitsubishi Paper Mills.
Test chart image exposure was carried out at -11, and after toner development, etching was performed with an organic alkaline solvent.
Image reproducibility as a plate-making master is good,
It was found that it had excellent performance as a master.

Example 3 As a charge generating agent, an ε-type copper phthalocyanine (manufactured by Toyo Ink) pigment and acrylic acid methyl ester-acrylic acid copolymer resin (acid value 130) were blended at a pigment/binder ratio of 1/3 by weight. 2.5 in toluene-butanol mixed solvent (1:1)
% using a dispersing machine, and using the dispersing machine, coating was carried out using an S-doctor onto a grained aluminum plate (120 µm) support so that the dry film thickness was 0.4 µm.

A solution was prepared by dissolving a mixture of 1 part by weight of the exemplary compound (3) of the present invention as a charge transfer substance and 1 part by weight of styrene-maleic anhydride half ester resin (acid value 160) to a concentration of 10% by weight of butyl acetate. A photoreceptor having a charge transfer layer having a dry film thickness of about 6 μm was obtained by coating the above charge generation layer.

The half-decrease exposure amount of this photoreceptor was 4.5 lux·sec.

As in Example 2, after exposure, development, and etching steps were performed using a plate-making machine, a gumming treatment was performed to obtain a printing plate master. When this master was printed on a printing machine, more than 10,000 printed images with good reproducibility could be obtained.

Claims (1)

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