JPH02285358A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and durability by incorporating a specified polyvalent indoline derivative in an electric charge transfer layer. CONSTITUTION:The electrophotographic sensitive body is composed essentially of a conductive substrate, a charge generating layer, and the charge transfer layer, and this charge transfer layer contains the indoline derivative represented by formula I in which each of R1 - R3 is alkyl or aryl; A is an aromatic hydrocarbon or heterocyclic group; and n is 2 or 3, thus permitting the obtained electrophotographic sensitive body to be stable in potential in an early stage, small in dark decay, high in sensitivity, small in deterioration due to repeated uses, and superior in durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly, to a highly sensitive electrophotographic photoreceptor containing a specific polyvalent indoline compound in a charge transport layer.
The present invention relates to a highly durable electrophotographic photoreceptor.

(Problems to be solved by conventional techniques and inventions) In recent years,
The development of copiers and printers that use electrophotography has been remarkable, with various forms and types of models being developed depending on their uses, and correspondingly, a wide variety of photoreceptors used in these machines are being developed. .

Conventionally, inorganic compounds have been mainly used as electrophotographic photoreceptors due to their sensitivity and durability. Examples of these inorganic compounds include zinc oxide, cadmium sulfide,
Examples include selenium. However, these often use harmful substances, and their disposal becomes a problem and causes pollution. Furthermore, when selenium, which has good sensitivity, is used, it is necessary to form a thin film on a conductive substrate by a vapor deposition method or the like, resulting in poor productivity and increased costs. In recent years, amorphous silicon has attracted attention as a non-polluting inorganic photoreceptor, and its research and development is progressing. However, although these also have excellent sensitivity, since plasma CVD is mainly used to form thin films, their productivity is extremely poor, and both photoreceptor cost and running cost are high.

On the other hand, organic photoreceptors can be incinerated and have the advantage of being non-polluting, and many of them can be coated to form thin films, making mass production easy. Therefore, it has the advantage of being able to significantly reduce costs and being able to be processed into various shapes depending on the application. However, problems remain in the sensitivity and durability of organic photoreceptors, and there is a strong desire for an organic photoreceptor with high sensitivity and high durability.

Various methods have been proposed to improve the sensitivity of organic photoreceptors, but currently the mainstream is a functionally separated photoreceptor with a two-layer structure in which the functions are separated into a charge generation layer and a charge transport layer. There is. For example, charges generated in the charge generation layer due to exposure to light are injected into the charge transport layer, transported through the charge transport layer to the surface, and by neutralizing the surface charges, an electrostatic latent image is formed on the surface of the photoreceptor. Compared to the single-layer type, the 0-function separated type has a smaller possibility that generated charges are captured, and the charges are efficiently transported to the surface of the photoreceptor without hindering each layer's respective functions. Obtain (U.S. Patent No. 2803
No. 541).

As the organic charge generating material used in the charge generating layer, compounds that absorb the energy of irradiated light and efficiently generate charges are selected. For example, azo pigments (
JP-A-54-14967), metal-free phthalocyanine pigments (JP-A-60-143346), metal phthalocyanine pigments (JP-A-50-16538), squareium salts (JP-A-53-27033) Public bulletin), etc. can be mentioned.

As the charge transport material used in the charge transport layer, it is necessary to select a compound that has high charge injection efficiency from the charge generation layer and also has high charge mobility within the charge transport layer.

For this purpose, compounds with small ionization potential,
Compounds that easily generate radical cations are selected, such as triarylamine derivatives (Japanese Patent Application Laid-Open No. 53-47260
Publication No.), hydrazone derivatives (Japanese Patent Application Laid-Open No. 57-10184
4), oxadiazole derivatives (Japanese Patent Publication No. 34-5)
466), pyrazoline derivatives (Japanese Patent Publication No. 52-41
No. 88), stilbene derivatives (JP-A-58-198)
043 Publication), triphenylmethane derivatives (Special Publication No. 4
5-555), 1,3-butadiene derivatives (JP-A-62-287257), and the like have been proposed.

However, the charge mobility of these materials is small compared to that of inorganic materials, and the sensitivity is still unsatisfactory.

Further, in a series of electrophotographic processes such as charging, exposure, development, transfer, and static elimination, photoreceptors are placed under extremely harsh conditions, and in particular, their ozone resistance and abrasion resistance become major problems. Durability is also required for the materials used in the photoreceptor, and while development of binders and protective layers is progressing, a satisfactory material has not yet been obtained.

[Means to solve the problem]

The present inventors have made intensive studies to solve the above problems and obtain a highly sensitive and highly durable electrophotographic photoreceptor, and as a result, an electrophotographic photoreceptor containing a specific polyvalent indoline compound in the charge transport layer has been developed. It was discovered that both sensitivity and durability were excellent, leading to the present invention.

That is, the present invention provides an electrophotographic photoreceptor comprising a conductive support, a charge generation layer, and a charge transport layer as essential components, wherein R+, Rz, and Rx are the same or Straight-chain or branched alkyl groups, which are different and may be substituted;
represents any aryl group that may be substituted, 8 represents an aromatic hydrocarbon group or heterocyclic group that may be substituted, and n is 2 or 3. ) The present invention provides an electrophotographic photoreceptor characterized by containing a compound represented by the following formula in a charge transport layer.

The method for synthesizing the above-mentioned polyvalent indoline compound is not particularly limited, but it can be synthesized according to the method normally used for synthesizing olefin compounds.

For example, an aldehyde compound represented by formula (2) (R+, Rg, R3 are the same as formula (1)) and (R, represents a lower alkyl group e Atn is the formula (1))
) can be synthesized by condensation method.

An electrophotographic photoreceptor containing a similar indoline compound is disclosed in JP-A No. 61-210364, but the compound shown therein is a monofunctional compound, and it is further polyfunctionalized. That is, by using the polyvalent indoline compound of the present invention, it has become possible to improve the performance of the photoreceptor, particularly in terms of sensitivity and durability.

Specific examples of the polyvalent indoline compounds used in the present invention include those shown in 2 below, but the present invention is not limited thereto.

Cll3 Cll3 C11゜ C113CB.

ShiIt3 CH3 CH3 CH.

CII* C11゜ CHs　C11a tus Cl3 C1h Cz It 5 CJs　CtIls l3 CJs　CzHs H3 11. cN3 ■3 Shi 11! cat3 utl co 1lls I;zus Shi■koshi■3 CtHs C! 84CI Hs C! H.

tH4CI H3 C11゜ CI(3 CHI d14CI C■.

Js CHI2 zHs C, H5 C11゜ C11゜ CH.

L C1h CH.

CHl lls I'I CH3C1+.

CI+3 CH3 Hi C1(3 C1!3 C113 CH3C[+3 CH3CH3 Among these, compounds in which ^ is a benzene ring or a substituted benzene ring, that is, bisindoline styryl compounds or trisindoline styryl compounds, are easy to synthesize and are suitable for electrophotography. It is preferable because it also has excellent physical properties.

These compounds can be used alone or in combination of two or more.

These compounds are soluble in many solvents, e.g.
Aromatic solvents such as benzene, toluene, xylene, tetralin, and chlorobenzene; Halogen solvents such as dichloromethane, chloroform, trichloroethylene, and tetrachloroethylene? V agent; ester solvents such as methyl acetate, ethyl acetate, propyl acetate, methyl formate, and ethyl formate; ketone solvents such as acetone and methyl ethyl ketone; ether solvents such as diethyl ether, dipropyl ether, dioxane, and tetrahydrofuran; It is soluble in alcoholic solvents such as methanol, ethanol, and isopropyl alcohol, dimethylformamide, dimethylacetamide, dimethylsulfoxide, and the like.

In producing an electrophotographic photoreceptor, a charge generation layer and a charge transport layer are formed in the form of a thin film on a conductive support. As the base material of the conductive support, metals such as aluminum and nickel, metal-deposited polymer films, metal-laminated polymer films, etc. can be used, and the conductive support is formed in the form of a drum or sheet. .

The charge generation layer is made of a charge generation material and, if necessary, a binder and additives, and can be produced by a method such as a vapor deposition method, a plasma CVD method, or a coating method.

The charge generating material is not particularly limited, and any organic or inorganic material can be suitably used as long as it absorbs irradiated light of a specific wavelength and can efficiently generate charges. .

Examples of organic charge generating materials include perylene pigments, polycyclic quinone pigments, metal-free phthalocyanine pigments, metal phthalocyanine pigments, bisazo pigments, trisazo pigments, thiapyrylium salts, squareium salts, and azulenium pigments. A charge generation layer can be formed by dispersing it in a binder and coating it. Inorganic charge generating materials include selenium, selenium alloys, cadmium sulfide,
Examples include zinc oxide, amorphous silicon, and silicon carbide.

The thickness of the formed charge generation layer is preferably from 0.1 to 2.0, more preferably from 0.2 to 1.0.

Next, a charge transport layer containing a compound represented by formula (1) is formed in the form of a thin film on top of the charge generation layer. A coating method is mainly used to form a thin film, in which the compound shown by the hole (1) is dissolved in a solvent together with a binder if necessary, coated on the charge generation layer, and then dried. That's fine.

The solvent to be used is not particularly limited as long as it dissolves the above-mentioned compound and the binder used if necessary, but does not dissolve the charge generation layer.

The binder used as necessary is not particularly limited as long as it is an insulating resin, and examples thereof include condensation polymers such as polycarbonate, polyarylate, polyester, and polyamide; polyethylene, polystyrene, styrene-acrylic copolymer, Polyacrylate, polymethacrylate, polyvinyl butyral, polyacrylonitrile, polyacrylamide, acrylonitrile-butadiene copolymer,
Addition polymers such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymers; polysulfones, polyethersulfones, silicone resins, etc. are used as appropriate, and they can be used alone or in a mixture of two or more.

The amount of the binder used is 0.1 to 3 weight ratio, preferably 0.1 to 2 weight ratio with respect to the compound represented by general formula (1). If the amount of binder is greater than this, the concentration of the charge transport material in the charge transport layer will be low, resulting in poor sensitivity.

Further, in the present invention, it is also possible to use a combination of known charge transport materials as described above, if necessary.

The coating means for the charge transport layer is not limited, and for example, a bar coater, calendar coater, gravure coater, blade coater, spin coater, dip coater, etc. can be used as appropriate.

The thickness of the charge transport layer thus formed is preferably 10 to 504 μm, more preferably 10 to 30 μm. If the film thickness is greater than 50 -, it will take more time to transport the charge, and the probability that the charge will be captured will also increase, causing a decrease in sensitivity. On the other hand, if it is less than 10, the mechanical strength will decrease and the life of the photoreceptor will be shortened.
Although it is possible to produce an electrophotographic photoreceptor containing the compound shown in 1) in the charge transport layer, in the present invention, an undercoat layer and an adhesive layer are further added between the conductive support and the charge generation layer as necessary. , a barrier layer, etc. may be provided, and these layers may be made of, for example, polyvinyl butyral, phenolic resin, polyamide IJIM, or the like. Furthermore, a surface protective layer can also be provided on the surface of the photoreceptor.

When using the electrophotographic photoreceptor thus obtained, first the surface of the photoreceptor is negatively charged using a corona charger or the like. After being charged, charges are generated in the charge generation layer by exposure to light, and positive charges are injected into the charge transport layer, which are transported through the charge transport layer to the surface, neutralizing the negative charges on the surface. Ru. On the other hand, negative charges remain in the unexposed areas, which form an electrostatic latent image. Toner adheres to this area, is transferred onto paper, etc., and is fixed.

Further, in the present invention, it is also possible to produce an electrophotographic photoreceptor by first providing a charge transport layer on a conductive support and then providing a charge generation layer thereon. In this case, the surface of the photoreceptor is first positively charged, and after exposure, the generated negative charges neutralize the surface charges of the photoreceptor, and the positive charges are transported to the conductive support through the charge transport layer. It's going to happen.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Synthesis Example 6 56.4 g (0.2 mol) of diethyl phosphonate synthesized from p-xylylene dichloride was placed in a 214-bottle flask equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a dropping funnel, and ethylene glycol was added. Dimethyl ether11.
It was dissolved in Sodium hydride (60% oily)
20 g was added at room temperature and stirred for 1 hour. There, the formula (10
B) 105.2 g of aldehyde compound (0,
4 mol) of ethylene glycol dimethyl ether was added dropwise, and after the dropwise addition was completed, the temperature was raised to 85°C and stirred at that temperature for 5 hours. The reaction mixture was then cooled to room temperature and poured into 2Il of water. Furthermore, 2N ethyl acetate was added and mixed well, and the ethyl acetate layer was separated. This ethyl acetate solution was washed twice with water and dried over anhydrous sodium sulfate. After drying, ethyl acetate was distilled off under reduced pressure to obtain a yellow solid, which was recrystallized from n-hexane/ethyl acetate (5/1).
93 g (yield 78%) of yellow crystals were obtained.

Example-1 5 g of χ-type metal phthalocyanine and 5 g of vinyl chloride/vinyl acetate resin (manufactured by S-LEC C1 Sekisui Chemical Co., Ltd.) were dissolved in 90-cyclohexanone and kneaded in a ball mill for 24 hours. The obtained dispersion was applied onto an aluminum plate using a bar coater so that the film thickness after drying was 0.5 ts, and dried to form a charge generation layer.

Next, 5 g of compound (6) obtained in the synthesis example and 5 g of polycarbonate resin (Lexan 141-111, manufactured by Engineering Plastics ■) were dissolved in dioxane 90-, and this was coated on the previously formed charge generation layer using a blade coater. A charge transport layer was formed by coating and drying the film so that the film thickness after drying was 25 cm.

The electrophotographic photoreceptor produced in this manner was used with an electrostatic copying paper tester f! manufactured by Nichidenki Seisakusho. When charged with a corona voltage of -6.5 kV using PA-8100, the initial surface potential v0 was -770V. The surface potential V after being left in the dark for 5 seconds was -750V.

Next, a semiconductor laser with an oscillation wavelength of 790 nn+ was irradiated, and the half-decreased exposure amount El/1 was calculated, which was 0.41 a.
J/cm", and the residual potential Vl was -11V.

Next, after repeating the above operation 5000 times, vo.

When Vs+ Etztx Vm was measured, they were -750V, 730V, 0.41, 17J/Cl, respectively.
1 l'' and -13 Vt', and it was found that the performance as a photoreceptor had hardly deteriorated and showed high durability.

Examples 2 to 45 Photoreceptors were prepared in the same manner as in Example 1, except that the compounds shown in Table 1 were used as charge transport materials, and performance evaluation was performed. The results are shown in Table 1.

Table 1 continued Table 1 continued Table 1 continued Table 1 continued Table 1 continued Example-46 In Example-1, the χ type metal phthalocyanine was replaced by the formula (109). A photoreceptor was produced in exactly the same manner except that an azo compound containing 100% of the photoresist was used as the charge generating material, and evaluation was conducted in the same manner except that a halogen lamp with an illumination intensity of 51 ux was used as the irradiation light source instead of a 790 nA semiconductor laser. .

As a result, initial (7) Vo, Vs, Eryt, V
O is -780V, 770V, 1.51u respectively
x-sec, -17V, after 5000 times (DVo,
Vs, Lit, and VO are each -770V.

It was found that the performance as a photoreceptor was excellent at -750V, 1.71ux-sec, and -21V, and that it exhibited high durability.

(109) Comparative Example A photoreceptor was prepared and evaluated in exactly the same manner as in Example-1 except that the compound represented by formula (110) was used instead of the compound represented by formula (6). .

As a result, the initial VO, Vs, El/! lν, -830V, -820ν+ 1.1μJ/cm, respectively
", 37V, -850V after 5000 times, -84
0V, 1.3μJ/cm", with -67V, sensitivity,
Both durability was poor.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention, which is characterized by containing a specific polyvalent indoline compound in its charge transport layer, has a stable initial potential, small dark decay, and high sensitivity. Furthermore, it shows little deterioration due to repeated use and has excellent durability.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor comprising a conductive support, a charge generation layer, and a charge transport layer as essential components, which has the general formula (1
) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, and R_3 are the same or different and represent an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, etc.) represents either
A represents an optionally substituted aromatic hydrocarbon group or a heterocyclic group, and n is 2 or 3. ) An electrophotographic photoreceptor comprising a compound represented by the following formula in a charge transport layer. 2. Claim 1 in which A is a benzene ring or a substituted benzene ring
The electrophotographic photoreceptor described above.