JPH01252964A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain superior electric chargeability and photosensitivity characteristics by incorporating a specified stilbene compound in a photosensitive layer. CONSTITUTION:The stilbene compound contained in the photosensitive layer incorporates at least one of the compounds represented by formula I in which R1 is optionally substituted >=3C alkyl or optionally substitute aryl; each of R2 and R3 is optionally substituted alkyl, aralkyl, or the like; and each of (n), (m), and (l) is 1-5, thus permitting the obtained photosensitive body to be superior in photosensitivity, electric chargeability characteristics, and resistance to rise of residual potential, and small in deterioration of various characteristics due to repeated uses and changes of various environmental conditions.

Description

Detailed Description of the Invention (Objective of the Invention) <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor that is effective using the Carlson method, and more specifically, it has excellent photosensitivity, charging characteristics, and residual potential characteristics. This invention relates to an electrophotographic photoreceptor with good stability and durability.

(Prior Art) The photoconductive process of an electrophotographic photoreceptor is separated from a photocharge generation process and a charge transport process. Conventionally, electrophotographic photoreceptors have two methods: a method in which the above two processes are performed using one substance, and a method in which the two processes are performed using separate materials.

Of the two methods described above, the method in which each process is performed using separate substances has a wider range of material selection for the photoreceptor, and the resulting photoreceptor has excellent electrophotographic properties such as sensitivity and acceptance potential. When producing a photoreceptor, it has the advantage of being able to produce a photoreceptor with excellent coating properties.

As this type of function-separated and laminated photoreceptor, the following ones are known, for example.

However, such conventionally known photoreceptors have several problems. For example, in a photoreceptor using amorphous selenium, the polvinyl carbazole used in the charge transport layer lacks flexibility, so the formed layer is hard and brittle, and is prone to cracking and peeling.
The drawback is that it has poor durability as a photoreceptor. Therefore, in order to increase the flexibility of polyvinylcarbazole, a method of using it together with a plasticizer has been proposed. However, this method has a major drawback in that residual charges in the charge transport layer increase, resulting in deterioration of electrophotographic properties such as fogging of images.

Also, for example, triphenylmethane, carbazole conductor, 2,5-bis(p-diethylaminophyl)-1,
Some photoreceptors using low-molecular-weight organic compounds as charge transport materials, such as 3,4-oxadiazole, have relatively poor electrophotographic properties, but generally do not have the ability to form a film. A charge transport layer is formed by using a polymer binder having film-forming ability. However, these low molecular weight organic compounds generally have poor compatibility with polymer binders, even if they have excellent electrophotographic properties.
When a film is formed as a charge transport layer, it tends to crystallize and has poor thermal stability.

Furthermore, it goes without saying that materials with good photosensitivity are required for electrophotographic properties, but none of the conventionally known photoreceptors mentioned above have sufficient sensitivity, and moreover, even when subjected to repeated exposure charging, Many of them cause fluctuations in surface potential, especially a decrease in charge retention ability. Also, changes in the environment,
In particular, it has the disadvantage that sensitivity and image contrast change with changes in humidity.

(Problems to be Solved by the Invention) As mentioned above, conventional electrophotographic photoreceptors have problems with flexibility and compatibility with polymeric binders, and also suffer from deterioration of photosensitivity and characteristics due to repeated use. There is a problem with deterioration of characteristics due to the environment.

The present invention eliminates these drawbacks of conventional electrophotographic photoreceptors and has excellent flexibility, excellent photosensitivity, charging characteristics, and residual potential characteristics, and also prevents deterioration of various properties due to repeated use and changes in various environments. The object of the present invention is to provide a small electrophotographic photoreceptor.

(Structure of the Invention) (Means for Solving the Problem) In order to achieve the above object, the present inventors have developed various low molecular weight organic compounds as charge transport substances used in the photosensitive layer of an electrophotographic photoreceptor. After much research, we have arrived at the present invention.

That is, it is an electrophotographic photoreceptor comprising an electrically conductive support and a photosensitive layer laminated on the electrically conductive support, where the photosensitive layer contains at least one type of stilbene compound.

In particular, the stilbene compound of the photosensitive layer has the following general formula (1
) is characterized by containing at least one compound represented by.

(iX lower margin) In the general formula, R2 and R3 are an optionally substituted alkyl group, aralkyl group, or aryl group.

heterocyclic group, -0-R4 (R4 is substituted Alkyl group, aralkyl group that may be group, aryl group, heterocyclic group).

-N'l:R5 (R5 and R6 are optionally substituted alkyl groups and aralkyl groups.

Aryl group or R5, Re N-containing heterocycle), hydrogen, halogen cyano group, nitro group.

In R1, R2 and R3 are both not hydrogen, n = 1, and at least one of R2 and R3 is -x CR5, and R2 and R3 are two or more -N, -R5 In the case, \R6 optionally substituted alkyl group with C≧3, -0-R7 (R7 is optionally substituted alkyl group with C≧3, aralkyl group, heterocyclic group, hydrogen), cyan group, nitro group , halogen, optionally substituted aryl group, heterocyclic group.

Both R2 and Substitute 3 are not hydrogen, and n=1 and R2, R3 are small -N<R5 where at least one is two or more or either R2 or R3 If not -N-R5, C≧2 \R6 an optionally substituted alkyl group, - 〇-R7, heterocyclic group, cyano group, di ]~group, halogen, hydrogen, substituted optional aryl group, heterocyclic group.

Both R2 and R3 are not hydrogen and n In the case of ≧2, optionally substituted alkyl Kyl group, aralkyl group, -0-Ra (Ra is optionally substituted alkyl group, aralkyl group, aryl group, cyclic group, hydrogen), cyan group, di] ~ b groups, halogens, and hydrogen may be substituted. aryl group, heterocyclic group.

Both R2 and R3 are hydrogen and If n≦3, may be replaced. aralkyl group, aryl group, hetero cyclic group, -0-R9 (R9 is substituted optional aralkyl group, 71-nol group Hydrogen>, cyan group, nitro group.

R2 and R3 are both hydrogen and n 41, may be replaced Alkyl group, aralkyl group, aryl group group, heterocyclic group, -0-Ra, Ano group, nitro group, halogen, water Basic.

n=1 to 5, m=1 to 5, and R=1 to 5, respectively.

The present invention provides, for example, a separable single-layer photoreceptor comprising at least one layer of a charge generating material and a charge transporting material on a conductive substrate, and at least two layers of a charge generating layer and a charge transporting layer on a conductive substrate. The present invention can be applied to any type of electrophotographic photoreceptor, such as a functionally separated laminated photoreceptor in which a charge transport layer and a charge generation layer are sequentially laminated, or at least two charge transport layers and a charge generation layer are sequentially laminated.

Hereinafter, the structure of the present invention will be explained in detail by taking a function-separated layered photoreceptor as an example.

The conductive support used in the present invention is not particularly limited, and may be any support that is normally used as a conductive support for electrophotographic photoreceptors. Such supports include, for example, metal materials such as brass, aluminum, gold, and silver; metal surfaces coated with a thin film of plastic; metal-coated paper, metal-coated plastic sheets, or aluminum iodide. , glass coated with a conductive layer such as copper iodide, chromium oxide or tin oxide. These are used as thin cylindrical sheets with appropriate thickness, hardness, and flexibility, and either the support itself is conductive or its surface is conductive, and has sufficient strength for handling. It is preferable that the

A charge generation layer or a charge transport layer, which will be described later, is formed on such a conductive support.

The charge generation layer may be made of any charge generation material as long as it absorbs light and generates charges (carriers) with high efficiency.

Such charge-generating substances include, for example, selenium and selenium alloys; inorganic photoconductors such as CdS, CdSe, Cd5Se, ZnO, and ZnS; phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine; monoazo dyes and disazo dyes. Azo dyes; penylene pigments such as benylene anhydride and penylene imide; indigoid dyes; quinacridone pigments; polycyclic quinones such as anthraquinones and pyrenequinones; xanthine dyes; electrons such as poly-N-vinyl carbazole Examples include a charge transfer complex consisting of a donating substance and an electron accepting substance such as trinitrofluorenone, and a eutectic complex consisting of a pyrylium salt dye and a polycarbonate resin.

Methods for forming the charge generation layer vary depending on the type of charge generation substance used, but include various coating methods such as spin coating, pulling method, roller coating method, doctor blade coating method, and vacuum evaporation. method, sputtering method, plasma CVD using glow discharge, etc.
The law can be selected and applied as appropriate.

The thickness of the charge generation layer to be formed at this time is appropriately determined depending on the charging characteristics required for the electrophotographic photoreceptor.
Usually, the length is preferably about 0.1 to 20 m.

Note that when forming the charge generation layer on the conductive support,
If desired, an adhesive pattern may be formed between the conductive support and the charge generating layer. As the material forming the adhesive layer, commonly used materials such as Kabiin can be used, and the thickness thereof is 0.1 to 10-1, preferably 0.5.
~2- level is good.

Next, the stilbene compound represented by the above formula (I) as a charge transport material used in the photosensitive layer of the electrophotographic photoreceptor in the present invention will be explained.

The photosensitivity of the present invention contains at least one of these stilbene compounds.

In the compound represented by formula (I) above, examples of the aryl group include a di-substituted amine group (e.g., dimethylani) group, diethylamino group, dibutylamino group, methylethylamino group, methylbutylamino group, cyamylamino group, etc. dialkylamino group; dibenzylamino group,
dialkylamine groups such as diphenethylamino group; diarylamino groups such as diphenylamino group, ditolylamino group, dixylylamino group> and alkoxy groups (e.g.
Methoxy group, ethoxy group, propoxy group, butoxy group>
and aryloxy groups (e.g., phenoxy and naphthoxy groups), alkyl groups, nitro groups, cyano groups, hydroxy groups, acetyl groups, and phenyl groups that may be substituted with halogens, naphthyl groups, anthracene groups, phenanthrene groups, and tetralin. group, azulene group, biphenylene group, acenaphthylene group, acenaphthene group, fluorene group,
Examples thereof include a fluoranthene group, a triphenylene group, a pyrene group, a chrysene group, a naphthacene group, a picene group, a perylene group, a benzopyrene group, a rubisene group, a coronene group, and an obalene group.

In the compound represented by formula (I) above, the aralkyl group includes, for example, a di-substituted amino group (e.g., dimethylamino group, diethylamino group, dibutylamino group,
A dialkylamino group such as a methylethylamino group, a methylbutylamino group, or a cyamylamino group; a dialkylamino group such as a dibenzylamino group or a diphenethylamino group;
diarylamino groups such as diphenylamino group, ditolylamino group, dixylylamino group), alkoxy groups (e.g. methoxy group, ethoxy group, propoxy group, butoxy group), aryl group, oxy group (e.g. phenoxy group,
naphthoxy group), alkyl group, nitro group, cyano group, hydroxy group, acetyl group, benzyl group, phenylpropyl group, phenylbutyl group, naphthylmethyl group, naphthylethyl group, etc. which may be substituted with acetyl group, halogen, etc. Can be mentioned.

In the compound represented by formula (I) above, the alkyl group includes, for example, a di-substituted amine group (e.g., dimethylamino group, diethylamine group, dibutylamino group, methylethylamino group, methylbutylamino group, cyamylamino group, etc.). dialkylamino group; dibenzylamino group;
dialkylamino groups such as diphenethylamino group; diarylamino groups such as diphenylamino group, diarylamino group, and dixylylamino group; alkoxy groups (e.g., methoxy group, ethoxy group, propoxy group, butoxy group) and aryloxy group (e.g., phenoxy group, naphthoxy group), methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group, which may be substituted with nitro group, cyano group, hydroxy group, acetyl group, halogen, etc. etc.

In the compound represented by formula (I), examples of the heterocyclic group include a pyrrole ring group, an indole ring group, an indoline tM'4, an isoindole ring group, a carbazole ring group, a furan ring group, a benzofuran ring group, and a thiophene ring. group, pyrazole ring group, pyrazoline ring group, benzopyrazole ring group, imidazole ring group, imidacillin ring group, benzimidazole ring group, oxazole ring group, benzoxazole ring group,
Naphthoxazole ring group, oxazoline ring group, thiazole ring group, thiazoline ring group, benzothiazoline ring group, triazole ring group, benzotriazole ring group, oxadiazole ring group, thiadiazole ring group, benzoxadiazole ring group, benzothiadiazole ring group Ring group, tetrazole ring group, pyridine ring group, quinoline ring group, acridine ring group, phenanthrene ring group, benzoquinoline ring group, naphthoquinoline ring group, pyran ring group, benzopyran ring group, thiapyran ring group, pyridazine ring group, pyrimidine ring group, pyrazine, oxazine ring group, benzoxazine ring group, thiazine ring group, benzodeazine ring group, phenothiazine ring group, dioxane ring group, 1 to riazine ring group, oxadiazine ring group, thiadiazine ring group, tetralin group, benzofuran ring group, Thiazole ring group, benzothiazole ring group, naphthothiazole ring group,
Examples include a selenazole ring group, a benzoselenazole ring group, a naphthoselenazole ring group, and the like.

Substituents for organic groups constituting the above-mentioned heterocyclic groups, aryl groups, aralkyl groups, alkyl groups, etc. include, for example, alkyl groups such as methyl, ethyl, and propyl; methylene, ethylene, and propylene groups; Alkylene groups such as methoxy groups, hydroxyl groups, etc.; Aryloxy groups such as phenoxy groups; halogen atoms such as chlorine and bromine; dialkyl groups such as dimethylamino groups, diethylamino groups, and ethylbutylamino groups. Amino group; diarylamino group such as diphenylamino group; alkylarylamino group such as ethylphenylamino group; alkylthio group such as methylthio group, ethylthio group, nitro group; cyano group, amino group; hydroxyl group; methyl ester group, ethyl Ester groups such as ester groups and phenyl ester groups; amide groups such as phenylamide groups and dimethoxyphenylamide groups; group, dialkylamino groups such as siamylamino group; dialkylamino groups such as dibenzylamino group and diphenethylamino group; diphenylamino group,
Diarylamino groups such as ditolylamino group and dixylylamino group>, alkoxy groups (e.g. methoxy group, ethoxy group, propoxy group, butoxy group), aryloxy groups (e.g. phenoxy group, naphthoxy group), alkyl groups, yanitro groups, etc. Phenyl group, naphthyl group, anthracene group, phenanthrene group, tetralin group, azulene group, biphenylene group, acenaphthylene group, acenaphthene group, fluorene group, fluoranthene group, which may be substituted with cyano group, hydroxy group, acetyl group, halogen, etc.
Aryl groups such as trinoenylene group, pyrene group, chrysene group, naphthacene group, picene group, perylene group, benzopyrene group, rubicene group, coronene group, obalene group; di-substituted amine group (e.g. dimethylamino group, diethylamine group, dibutylamino group) dialkylamino groups such as methylethylamino, methylbutylamino, and cyamylamino groups; dialkylamino groups such as dibenzylamino and diphenethylamino groups; diaryls such as diphenylamino, ditolylamino, and dixylylamino groups; amino group)
, alkoxy groups (e.g. methoxy, ethoxy, propoxy, butoxy), aryloxy groups (e.g. phenoxy, naphthoxy), argyl, nitro, cyano, hydroxy, acetyl, halogen, etc. Optionally substituted benzyl group, phenethyl group,
Examples include aralkyl groups such as phenylpropyl group, phenylbutyl group, naphthylmethyl group, and naphthylethyl group.

Specific examples of the stilbene compounds represented by the above-mentioned formula (I) using structural formulas include those shown in Table 1 below.

In addition, R1. shown in Table 1 below. R2 and R3 correspond to the following structural formula.

(Left below) When forming a charge transport layer containing the compound represented by general formula (I) as an essential component, since none of these compounds have film-forming properties, high It is necessary to form a layer by using a resin solution prepared by dissolving a molecular compound in a suitable organic solvent as a binding component.

Examples of such polymer compounds include polycarbonate, polyester carbonate, and polystyrene.
j< 1-vinyl chloride, acrylic resin, vinyl chloride-
Known bonding materials for electrophotographic photoreceptors include vinyl acetate copolymers, polyvinyl acetates, polyvinyl acetals, phenolic resins, styrene-acrylic copolymers, polyarylates, and alkyd resins.

Then, in layer formation, the above-mentioned stilbene compound 1
The above-mentioned polymer compound is preferably added in an amount of 0.1 to 0.1 to parts by weight.
A solution obtained by dissolving or dispersing 5 parts by weight in an organic solvent such as aliphatic chlorine, aromatic hydrocarbon, aromatic chlorine, ether, ester, ketone, etc. The coating method may be, for example, a spin coating method, a pulling method, a roller coating method, a daughter blade coating method, etc., on the charge generating layer or on the conductive support, and then drying.

Note that the above-mentioned stilbene compounds may be used in combination of two or more types, or may be used in combination with a known charge transporting substance within a range that does not impair the effects of the present invention.

As for the thickness of the charge transport layer, it is usually preferable that the total thickness of the charge generation layer and the charge transport diagram is 100 or less. This is because if the total thickness exceeds 100 m, the flexibility and photosensitivity of the formed film will decrease.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Examples 1 to 6 A polyethylene terephthalate film on which aluminum was vapor-deposited was used as a conductive support, and a charge-generating substance shown in Table 2 below was laminated by a coating method on the surface on which aluminum was vapor-deposited. A charge generation layer having the thickness shown in Table 2 was formed.

Roughly selecting the compounds shown in Table 2 from among the stilbene compounds numbered in Table 1 above,
A solution prepared by dissolving this stilbene compound and the polymer compound shown in Table 2 was coated using a pulling method, dried at 90°C for 24 hours, and then the charge transport film had a film thickness shown in Table 2. formed a layer.

Measure the charging ability (the initial value of the surface potential of the photoconductor after charging) and the photosensitivity (the amount of light exposure necessary for the initial value of the surface potential to attenuate by half) of the photoconductor thus obtained. did.

The results are also shown in Table 2.

In addition, this photoreceptor can be placed in an environment where heat, ozone, etc. are generated.
When the exposure was repeated io, ooo times, it was found that almost no abnormalities were observed, and the fluctuations in charging ability, photosensitivity, residual potential, etc. were small, and the fatigue resistance properties were excellent.

Comparative Examples 1 and 2 Electrophotographic photoreceptors were produced in the same manner as in Examples, except that a pyrazoline reading conductor was used as the charge transport material.

The charging ability, photosensitivity, dark decay rate, and residual potential of this photoreceptor were measured and shown in Table 2.

When this photoreceptor was repeatedly charged and exposed 10,000 times in an environment where heat, ozone, etc. were generated, changes in charging ability, photosensitivity, residual potential, etc. were observed, and the fatigue resistance properties were as good as those of Examples 1 to 6. It was inferior in comparison.

Examples 7 to 12 To a 5% by weight solution 5009 of the polymer compound shown in Table 3,
5q of charge generating substances shown in Table 3 were added and dispersed in a ball mill to prepare a paint. To this paint, select the compound shown in Table 3 from among the compounds numbered in Table 1, add this compound to the charge generating substance at a 5 mol ratio, apply it, and dry. , a photosensitive layer was formed. The chargeability and photosensitivity of the photoreceptors thus prepared were measured in the same manner as in Examples 1 to 6. The results are also shown in Table 3.

When this photoreceptor was repeatedly charged and exposed io and ooo times in an environment where heat, ozone, etc. were generated, no abnormalities were observed, and fluctuations in charging ability, photosensitivity, residual potential, etc. were small, and fatigue resistance was achieved. It turned out to be excellent.

Comparative Examples 3-4 Example J except that an existing compound was used as the charge transport material
Photosensitivity was prepared in the same manner as in 12. The charging ability and photosensitivity of this photoreceptor were measured and shown in Table 3.

When this photoreceptor was repeatedly charged and exposed to light in an environment where heat, ozone, etc. were generated, the charging ability, photosensitivity,
Fluctuations in residual potential, etc. were observed, and the fatigue resistance was as low as that of Example 7.
It was inferior compared to 12.

Examples 13 to 18 The compound shown in Table 4 was selected from the compounds numbered in Table 1, and a solution containing compound 59 and 5 g of the polymer compound shown in Table 4 was placed on aluminum Mylar. and dried to form a charge transport layer.

On this charge transport layer, a charge generating material 1. shown in Table 4 is applied.
A paint in which 11.5 g of the compound numbered No. 59 in Table 1 or a known charge transporting material was dispersed together with the polymer compound solution shown in Table 4 was applied and dried to form a charge generation layer. The chargeability and photosensitivity of the photoreceptors thus prepared were measured in the same manner as in Examples 1 to 6. The result is the fourth
Also shown in the table.

When this photoreceptor was repeatedly charged and exposed to light in an environment where heat, ozone, etc. were generated, almost no abnormalities were observed, and fluctuations in charging ability, photosensitivity, residual potential, etc. were small, and fatigue resistance was achieved. It turned out to be excellent.

Comparative Examples 5-6 Example 13 except that an existing compound was used as the charge transport layer
A photoreceptor was prepared in the same manner as in steps 1 to 18. The charging ability and photosensitivity of this photoreceptor were measured and shown in Table 4.

When this photoreceptor was charged and exposed 10,000 times in an environment where heat, ozone, etc. were generated, variations in charging ability, photosensitivity, residual potential, etc. were observed, and the fatigue resistance properties of Examples 13 to 18 were observed.
was inferior compared to

(The following is a blank space) Table [Effects of the Invention] The electrophotographic photoreceptor of the present invention has excellent charging characteristics such as high charging ability, and excellent photosensitivity characteristics such as low half-life exposure. In addition, the electrophotographic photoreceptor of the present invention is stable against light, heat, and ozone, maintains stable charging characteristics, photosensitivity characteristics, and residual potential characteristics even when used for a long time, and has excellent durability. have sex.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer provided on the conductive support, wherein the photosensitive layer is made of a stilbene compound represented by the following general formula (I). An electrophotographic photoreceptor characterized by containing at least one type of photoreceptor. General formula: ▲There are numerical formulas, chemical formulas, tables, etc.▼……(I) In the formula, R_2 and R_3 are optionally substituted alkyl groups, aralkyl groups, aryl groups, heterocyclic groups, -O-R_4
(R_4 is an optionally substituted alkyl group, aralkyl group, aryl group, heterocyclic group), ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (R_5, R_6 are optionally substituted alkyl groups, aralkyl groups, aryl groups, Alternatively, R_5 and R_6 form an N-containing heterocycle), hydrogen, halogen, cyano group, nitro group, R_1 is R_2,
Both R_3 are not hydrogen, and n=1, and R_
2. If at least one of R_3 is ▲There is a mathematical formula, chemical formula, table, etc.▼ and two or more R_2 and R_3 are not ▲There is a mathematical formula, chemical formula, table, etc.▼, then C≧3 substitution an optionally substituted alkyl group, -O-R_7(
R_7 is a C≧3 optionally substituted alkyl group, aralkyl group, heterocyclic group, hydrogen), cyano group, nitro group, halogen, optionally substituted aryl group, heterocyclic group, R_2
, R_3 are not hydrogen, and n=1, and R_
2. If at least one of R_3 is two or more ▲There are mathematical formulas, chemical formulas, tables, etc.▼, or R_2, R_3
If neither of these ▲ has mathematical formulas, chemical formulas, tables, etc. ▼, C≧2 optionally substituted alkyl group, -O-R_
7, heterocyclic group, cyano group, nitro group, halogen, hydrogen,
Aryl group, heterocyclic group, R_2, R_ which may be substituted
When both 3 are not hydrogen and n≧2, an optionally substituted alkyl group, an aralkyl group, -O-R_8(R_8
is an optionally substituted alkyl group, aralkyl group, aryl group, heterocyclic group, hydrogen), cyano group, nitro group, halogen, optionally hydrogen-substituted aryl group, heterocyclic group, R_
2. When both R_3 are hydrogen and n≦3, an optionally substituted aralkyl group, aryl group, heterocyclic group, -O-R_9 (R_9 is an optionally substituted aralkyl group, aryl group hydrogen), cyano group, nitro group, R_2
, R_3 are both hydrogen and n>3, an optionally substituted alkyl group, aralkyl group, aryl group,
Represents a heterocyclic group, -O-R_8, cyano group, nitro group, halogen, hydrogen, n=1-5, m=1-5, l=1-5, respectively.