JPH03116152A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance mechanical characteristics and to form a photosensitive body high in sensitivity by forming a photosensitive layer containing a specified thioether type compound. CONSTITUTION:The photosensitive layer contains the thioether type compound represented by formula I, in which R<1> is H or halogen; each of R<2> and R<3> is H, lower alkyl, aralkyl, or optionally substituted phenyl; R<4> is H, lower alkyl, halogen, or nitro; and (n) is 0 or 1, thus permitting the obtained photsensitive body to be high in sensitivity and small in residual photential causing fog and superior in durability.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an electrophotographic photoreceptor.

More specifically, the present invention relates to a highly sensitive electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductive substance.

<Prior Art> Conventionally, inorganic photoconductive substances such as selenium, cadmium sulfide, and zinc oxide have been widely used in the photosensitive layer of electrophotographic photoreceptors. However, selenium and cadmium sulfide need to be recovered as poisonous substances; selenium crystallizes when exposed to heat and has poor heat resistance; cadmium sulfide and zinc oxide have poor moisture resistance; and zinc oxide has disadvantages such as lack of rigidity resistance. Efforts are being made to develop new photoreceptors. Recently, research has progressed on the use of organic photoconductive substances in photosensitive layers of electrophotographic photoreceptors, and some of them have been put into practical use. Organic photoconductive materials have advantages over inorganic materials, such as being lightweight, easy to form a film, easy to manufacture photoreceptors, and depending on the type, transparent photoreceptors can be manufactured. have

Recently, so-called functionally separated photoreceptors, in which the functions of generating and transporting charge carriers are shared by separate compounds, have become the mainstream of development because they are effective in increasing sensitivity.
Organic photoreceptors of this type are also being put into practical use.

As the charge carrier transfer medium, there are cases in which a polymeric photoconductive compound such as polyvinylcarbazole is used, and a case in which a low-molecular photoconductive compound is dispersed and dissolved in a binder polymer.

<Problem to be solved by the invention> In particular, organic low-molecular photoconductive compounds can be easily modified in mechanical properties because polymers with excellent film properties, flexibility, and adhesive properties can be selected as binders. However, it has been difficult to find a compound suitable for making a highly sensitive photoreceptor.

<Means for Solving the Problems> The present inventors conducted intensive research on organic low-molecular photoconductive compounds that provide electrophotographic photoreceptors with high sensitivity and high durability, and found that specific thioether compounds are suitable. We have found that this is the case and have arrived at the present invention.

That is, the gist of the present invention is to provide a compound having the general formula CI) 2 ... (1) (wherein, R1 represents a hydrogen atom or a halogen atom, and R2
represents a hydrogen atom, a lower alkyl group, an aralkyl group, or a phenyl group that may have a substituent, R″ represents a hydrogen atom,
represents a lower alkyl group, an aralkyl group, or a phenyl group which may have a substituent, R4 represents a hydrogen atom, a lower alkyl group, a halogen atom, or a nitro group, and n represents O
The present invention relates to an electrophotographic photoreceptor characterized by having a photosensitive layer containing a thioether compound represented by (or 1).

The present invention will be described in detail below. The electrophotographic photoreceptor of the present invention contains a thioether compound represented by the above general formula (1) in the photosensitive layer.

In the general formula (I), R1 represents a hydrogen atom; or a halogen atom such as a chlorine atom or a bromine atom, and a hydrogen atom is particularly preferred.

In addition, RZ is a hydrogen atom; a lower alkyl group such as a methyl group, an ethyl group, or a propyl group; an aralkyl group such as a benzyl group or a phenethyl group; or a phenyl group, a tolyl group, a methoxyphenyl group, or a p-dialkylamino-phenyl group It represents a phenyl group which may have a substituent such as, but a hydrogen atom, a methyl group, and a phenyl group are preferable.

R″ is a hydrogen atom; a lower alkyl group such as a methyl group or an ethyl group; a benzyl group; an aralkyl group such as a phenethyl group; a phenyl group, a methoxyphenyl group, or a p-dialkylamino group.
It represents a phenyl group which may have a substituent such as a phenyl group, and a methyl group and a phenyl group are particularly preferred.

R4 represents a hydrogen atom; a lower alkyl group such as a methyl group or an ethyl group; a halogen atom such as a chlorine atom or a bromine atom; or a nitro group, with a hydrogen atom being particularly preferred. Further, n represents 0 or 1, and n=o is preferable.

The thioether compound represented by the above general formula (1) can be produced by a known method.

For example, the following general formula (II) 4 (In the above formula, X represents a halogen atom such as a chlorine atom or a bromine atom, and R4 has the same meaning as in the above general formula CI). ) is reacted with triphenylphosphine to produce a Wittig reagent, and the following general formula (III) or (mV) RZ (in the above formula, R1 , R2 and R3 are the above general formula (1)
has the same meaning as in . ) at a temperature of 10 to 200°C, preferably 20 to 100°C, in the presence of a known basic catalyst.

In these reactions, it is possible to obtain a highly purified product by known purification means such as recrystallization, sublimation, and columns after each step or after all steps, depending on the case.

Known organic solvents used in the reaction include N.

Examples of known basic catalysts include N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, dioxane, benzene, and toluene.
Examples include butyllithium, phenyllithium, sodium methoxide, sodium ethoxide, potassium t-butoxide, and the like.

The electrophotographic photoreceptor of the present invention has a photosensitive layer containing one or more thioether compounds represented by the above general formula (1).

The thioether compound represented by the general formula (1) exhibits extremely excellent performance as an organic photoconductor. Particularly when used as a charge transfer medium, it provides a photoreceptor with high sensitivity and excellent durability.

Various forms of the photosensitive layer of an electrophotographic photoreceptor are known, and the photosensitive layer of the electrophotographic photoreceptor of the present invention may be any of them.

For example, a photosensitive layer containing a 1,000-onythyl compound in a binder and, if necessary, a dye or an electron-withdrawing compound as a sensitizer; photoconductive particles and a thioether compound that generate charge carriers with extremely high efficiency when absorbing light; A photosensitive layer in which a thioether compound and a binder are added, a charge transfer layer consisting of a thioether compound and a binder, and a charge generation layer consisting of photoconductive particles that generate charge carriers with extremely high efficiency when absorbing light, or a charge generation layer consisting of photoconductive particles and a binder. Examples include laminated photosensitive layers.

In these photosensitive layers, known hydrazone compounds, stilbene compounds, etc., which have excellent performance as organic photoconductors, may be mixed together with the thioether compound represented by the general formula (I).

In the present invention, when the thioether compound represented by the above general formula (1) is used in the charge transfer layer of a photosensitive layer consisting of two layers, a charge generation layer and a charge transfer layer, the sensitivity is particularly high and the residual potential is small. Moreover, when used repeatedly, a photoreceptor can be obtained which exhibits less fluctuation in surface potential, lowered sensitivity, accumulation of residual potential, etc., and has excellent durability.

The electrophotographic photoreceptor of the present invention can be prepared using the general formula (
A thioether compound represented by [I] is dissolved in a suitable solvent together with a binder, and if necessary, photoconductive particles, sensitizing dyes, electron-withdrawing compounds, which generate charge carriers with extremely high efficiency when absorbing light, or , plasticizer,
It can be produced by applying a coating solution obtained by adding pigments and other additives onto a conductive support and drying it to form a photosensitive layer with a thickness of usually several microns to several tens of microns.

In the case of a photosensitive layer consisting of two layers, a charge generation layer and a charge transfer layer, the above coating liquid is applied on the charge generation layer, or the charge generation layer is applied on the charge transfer layer obtained by coating the above coating liquid. It can be manufactured by forming.

Examples of solvents for preparing the coating solution include tetrahydrofuran, 1.
Ethers such as 4-dioxane; methyl ethyl ketone,
Ketones such as cyclohexanone; aromatic hydrocarbons such as toluene and xylene; aprotic polar solvents such as N,N-dimethylformamide, acetonitrile, N-methylpyrrolidone, and dimethyl sulfoxide; ethyl acetate, methyl formate, methyl cellosolve acetate, etc. esters; Examples include solvents that dissolve thioether compounds such as chlorinated hydrocarbons such as dichloroethane and chloroform.

Of course, it is necessary to select one that dissolves the binder from among these. In addition, as a binder, styrene,
Polymers and copolymers of vinyl compounds such as vinyl acetate, vinyl chloride, acrylic esters, methacrylic esters, butadiene, polyvinyl acecool, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, phenoxy resin Examples include various polymers that are compatible with thioether compounds, such as silicone resins, epoxy resins, and the like. The amount of binder used is usually 0.5 to 30 times the weight of the thioether compound, preferably 0.5 to 30 times the weight of the thioether compound.
It is in the range of 7 to 10 times the weight.

As the photoconductive particles, dyes, and electron-withdrawing compounds to be added to the photosensitive layer, well-known ones can be used. Photoconductive particles that generate charge carriers with extremely high efficiency when absorbing light include inorganic photoconductive particles such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, cadmium sulfide, and amorphous silicon; copper phthalocyanine, perinone pigments, Examples include organic photoconductive particles such as thioindigo, quinacridone, perylene pigments, anthraquinone pigments, azo pigments, bisazo pigments, trisazo pigments, tetrakis azo pigments, and cyanine pigments. Examples of dyes include triphenylmethane dyes such as methyl violet, brilliant green, and crystal violet, thiazine dyes such as methylene blue, quinone dyes such as quinizarin, cyanine dyes, pyrylium salts, thiapyrylium salts, and benzobyrylium salts.

Examples of electron-withdrawing compounds that form charge transfer complexes with thioether compounds include chloranil, 2,3
-dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2-
Quinones such as chloroanthraquinone and phenanthrenequinone; 4 Aldehydes such as nitrobenzaldehyde; 9
-Penzoylanthracene, indandione, 3゜5-
Ketones such as dinitrobenzophenone, 2.4.7-dolinitrofluorenone, 2,4.5.7-tetranitrofluorenone, 3.3',5.5'-tetranitrobenzophenone; phthalic anhydride, 4-chloronaphthalic acid Acid anhydrides such as acid anhydrides; tetracyanoethylene, terephthalalmalononitrile, 9-anthrylmethylidenemalononitrile, 4-nitrobenzalmalononitrile, 4-(p
Cyano compounds such as -nitrobenzoyloxy)benzalmalononitrile; 3-benzalphthalide, 3-(α-cyano-p-nitrobenzal)phthalide, 3-(α-cyano-p-nitrobenzal)-4,5,6,7 Examples include electron-withdrawing compounds such as phthalides such as -tetrachlorophthalide.

Furthermore, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a well-known plasticizer in order to improve film formability, flexibility, and mechanical strength. For this purpose, the plasticizers added to the above coating solution include phthalate esters, phosphate esters,
Examples include epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and aromatic compounds such as methylnaphthalene.

When a thioether compound is used as a charge transfer medium in the charge transfer layer, the coating liquid may have the above composition, but photoconductive particles, dyes, electron-withdrawing compounds, etc. may be excluded or added in small amounts. In this case, the charge generation layer is a coating solution obtained by dissolving or dispersing the above-mentioned photoconductive particles and, if necessary, a binder polymer, an organic photoconductive substance, a dye, an electron-withdrawing compound, etc. in a solvent, and then drying. Examples include a thin layer made of the photoconductive particles, or a layer made of the photoconductive particles formed by means such as vapor deposition.

It goes without saying that the photoreceptor thus formed may also have an adhesive layer, an intermediate layer, a transparent insulating layer, etc., if necessary. As the conductive support on which the photosensitive layer is formed, any of those used in well-known electrophotographic photoreceptors can be used.

Specific examples include metal drums and sheets made of aluminum, stainless steel, copper, etc., and laminates and vapor deposits of these metal foils. Further examples include plastic films, plastic drums, paper, paper tubes, etc., which are coated with a conductive substance such as metal powder, carbon black, copper iodide, or polymer electrolyte together with a suitable binder to conductivity treatment. Other examples include plastic sheets and drums that contain conductive substances such as metal powder, carbon black, and carbon fibers and are made conductive.

<Effects of the Invention> The electrophotographic photoreceptor of the present invention has extremely high sensitivity and has a low residual potential that causes fogging, and is particularly resistant to optical fatigue, so that it does not accumulate residual potential due to repeated use, and has a low residual potential that causes fogging. It has the characteristics of small sensitivity fluctuations and excellent durability.

<Examples> Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following production examples and Examples unless the gist thereof is exceeded. In addition, "parts" in the examples indicate "parts by weight."

Production Example 1 24 parts of dried N,N-dimethylformamide 100
After that, 40 parts of triphenylphosphine was added under a nitrogen atmosphere and reacted to synthesize the Wittisoch reagent. Next, 17 parts of N-ethylcarbazole aldehyde was added as a powder.

Furthermore, 28% methanol of sodium methylate was added to the reaction system.
29 parts of the solution was added dropwise, and the reaction was then carried out under reflux for 1 hour.

After cooling, the reaction solution was poured into 250 parts of ice water, and further extracted and purified by conventional methods to obtain 12 parts of white crystals. (Melting point: 123-124 DEG C.) This compound was found to be a thioether compound represented by the following structural formula by the following elemental analysis, mass spectrometry and infrared absorption spectrum measurements (FIG. 1).

(Mass spectrometry measurement results) CztHIqN+ St MW = 329 M'' = 329 (Structural formula) Same as Production Example 1 except that N-methylcarbazolaldehyde was used in place of N-ethylcarbazolaldehyde used in Production Example 1. White crystals were obtained by manufacturing and purifying the compound (melting point: 128-130°C).This compound was found to be a thioether-based compound represented by the following structural formula, as determined by the following elemental analysis, mass spectrometry, and infrared absorption spectroscopy. It turned out to be a compound.

(Elemental analysis value) Ct + HI, N r S + (mass spectrometry result) Ct, H + 7N1 l MW = 3 M + = 31 (Structural formula) 1.4 parts of disazo pigment having the above structure and polyvinyl butyral resin (electrical Manufactured by Kagaku Kogyo Co., Ltd. #6000/C
), 0.7 parts of phenoxy resin (manufactured by Union Carbide Corporation, registered trademark PKHH) in 44 parts of methyl ethyl ketone and 15 parts of 4-methoxy-4-methylpentanone-2 in a sand grinder. Dispersion and atomization treatment was performed.

The weight of this dispersion after drying was 0.7 g on the aluminum vapor deposited layer that was vapor deposited on a polyester film with a film thickness of 75 μm.
/rrr was coated with a wire bar, and then dried to form a charge generation layer.

A coating solution prepared by dissolving 80 parts of the thioether compound having the following structural formula produced in Production Example 1 and 100 parts of polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd., registered trademark Corpilon E2000) in 900 parts of dioxane was applied onto this, and dried to form a film. Thickness 20
A charge transfer layer of μm was formed.

The sensitivity, that is, the half-decreased exposure (E%) of the electrophotographic photoreceptor having the two-layer photosensitive layer thus obtained was measured. It was O1ux-sec.The half-decreased exposure amount was first set at -5°2KV in a dark place.
charged by a corona discharge, then exposed to white light,
It was determined by measuring the amount of exposure required for the surface potential to attenuate to 2 times the initial surface potential.

Example 2 A photoreceptor was prepared in the same manner as in Example 1 except that the thioether compound produced in Production Example 2 was used instead of the 1,000-onythyl compound (Production Example 1) used in Example 1.
The sensitivity was measured in the same way as 2.5 1ux-s
It was ec.

Examples 3 to 13 Products were obtained in the same manner as in Example 1 except that the thioether compounds shown in Table 1 below, which were synthesized in the same manner as Production Examples 1 and 2, were used instead of the thioether compounds used in Example 1.2. The sensitivity of the electrophotographic photoreceptor is shown in the table below.

3

[Brief explanation of drawings]

FIG. 1 shows an infrared absorption spectrum of the thioether compound obtained in Production Example 1. Mitsubishi Chemical Corporation

Claims (1)

[Claims] (1) On the conductive support, there is a general formula [I] ▲mathematical formula, chemical formula, table, etc.▼... [I] (In the formula, R^1 represents a hydrogen atom or a halogen atom, and R
^2 represents a hydrogen atom, a lower alkyl group, an aralkyl group, or a phenyl group that may have a substituent, and R^3 represents a hydrogen atom, a lower alkyl group, an aralkyl group, or a phenyl group that may have a substituent. a phenyl group, R^4 represents a hydrogen atom, a lower alkyl group, a halogen atom, or a nitro group, and n represents 0 or 1). A photoreceptor for electrophotography.