JPH1090920A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly sensitive photoreceptor which is excellent in environmental resistance and ozone resistance, and can provide a satisfactory image without reducing the chargeability or sensitivity even by repeated use by containing a specified compound and a triarylamine compound. SOLUTION: This photoreceptor contains a compound represented by the formula I and a triarylamine compound. In formula I, R1 represents secondary or ternary alkyl group, R2 represents hydrogen atom, halogen atom, alkyl group, aryl group or alkoxy group, (n) represents an integer of 1-3, and Ar represents non-substituted aryl group. This triarylamine compound is a triphenylamine compound. Otherwise, the triarylamine compound is a compound represented by formula II. In the formula II, R3 represents substituted or non-substituted phenyl group, R4 represents hydrogen atom, or substituted or non-substituted phenyl group, R5 -R7 represent hydrogen atom, halogen atom, alkyl group or alkoxy group, and (m) represents an integer of 1-3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Conventionally, inorganic photoconductors such as selenium have been used in Carlson type electrophotographic image forming apparatuses. However, due to the problem of crystallization of amorphous selenium and the adverse effect on the environment when it becomes industrial waste, organic photoreceptors have been increasingly used.

[0003] The development of organic photoreceptors has been remarkable since the concept of generating the photocharge and separating the function of charging the surface of the photoreceptor from function was remarkable. In the lower charge generation layer, azo pigments, phthalocyanine pigments, condensed polycyclic pigments were used. The quantum efficiency has been improved by such methods as the above, and in the upper charge transport layer, attempts have been made to improve the charge mobility by improving the hole-transporting amine-based compound. .

[0004] However, not all of the problems of the photoreceptor have been solved at present. In the electrophotographic process, after charging the photoreceptor surface, an electrostatic latent image is formed by exposure, the electrostatic latent image is developed with toner, and then the visible image is transferred and fixed on paper or the like, and the image is formed. obtain. The photoreceptor is subjected to removal of remaining toner adhered, charge elimination, and surface cleaning, and is repeatedly used for a long time.

Therefore, the electrophotographic photoreceptor has not only electrophotographic characteristics such as good charging characteristics and sensitivity and low dark decay, but also printing durability, abrasion resistance and moisture resistance in repeated use. For example, it is required to improve the chemical resistance such as physical resistance and resistance to ozone, nitrogen oxides, and ultraviolet rays during exposure.

[0006] One of the phenomena considered to be caused by the lack of chemical resistance is image blurring. Image blur is one of the major problems that has not yet been completely overcome in practice. It is thought that nitrogen oxides generated from oil stoves in winter or ozone generated from corona chargers, and nitrogen oxides formed by reacting with nitrogen in the air (Kobayashi, Sato et al., J. Am. of Imaging S
ci. and Tec. vol39, number
6,485 (1995)).

Hitherto, it has been studied to add a hindered phenol compound or a hindered amine compound known as an antioxidant in order to increase the resistance to this kind of oxidizing agent (JP-A-63-18356, JP-A-63-18356). 1988-50
No. 849, JP-A-63-73256).

[0008] However, there are other problems with attempts to increase chemical resistance with antioxidants. That is, the hindered amine compound is liable to become a cation trap as in the case of an amine compound, and tends to cause an increase in residual potential and a decrease in sensitivity.
Even ordinary hindered phenol compounds, which are electrically inactive and should not adversely affect photoreceptor properties, are usually insulative in organic compounds and consequently charge transport material (CTM) concentration in the photoreceptor To lower the sensitivity and increase the residual potential.

This tendency is even greater in amine-based systems, and in recent years it has become a major problem when more durable and faster copying is desired.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-sensitivity photoreceptor which is excellent in environmental resistance and ozone resistance and which gives a good image without a decrease in charging ability and sensitivity in repeated use. Is to provide.

[0011]

Means for Solving the Problems The present inventors have found that a specific hindered phenol compound (general formula (1)) is used as an antioxidant in a photoconductor using a triaryl compound as a charge transport material (hole transport material). Was found to increase the sensitivity rather than the addition of an insulating organic compound. Based on this, the above object was achieved.

That is, the present invention has been attained by adopting the following constitution.

[1] An electrophotographic photoreceptor comprising a compound represented by the following general formula (1) and a triarylamine compound.

[0014]

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(Wherein R ₁ represents a secondary or tertiary alkyl group, and R ₂ represents a hydrogen atom, a halogen atom, an alkyl group,
Represents an aryl group or an alkoxyl group, n represents an integer of 1 to 3, and Ar represents a substituted or unsubstituted aryl group. [2] The electrophotographic photosensitive member according to [1], wherein Ar is a substituted or unsubstituted phenyl group.

[3] The electrophotographic photosensitive member according to [1] or [2], wherein the triarylamine compound is a triphenylamine compound.

[4] The electrophotographic photoreceptor according to [3], wherein the triarylamine compound is a compound represented by the following general formulas (2) to (5).

[0018]

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(Wherein R ₃ represents a substituted or unsubstituted phenyl group, R ₄ represents a hydrogen atom, a substituted or unsubstituted phenyl group, and R _{5 to} R ₁₇ represent a hydrogen atom, a halogen atom, an alkyl group Or represents an alkoxyl group, m represents an integer of 1 to 3, A and B each represent a substituted or unsubstituted alkyl group or an aryl group, and A and B may be bonded to each other to form a ring, Z represents a linking group, and k represents 0 or 1.) In the general formula (1), R ₁ is located at the o (ortho) position of the OH group, and represents a secondary or tertiary alkyl group. Examples of the secondary or tertiary alkyl group include an isopropyl group, a t-butyl group,
Examples include an isoamyl group. R ₂ represents a hydrogen atom, an alkyl group (a secondary or tertiary alkyl group is preferably, for example, an isopropyl group, a t-butyl group, an isoamyl group, etc.), an aryl group, an alkoxyl group, or a halogen atom; Represents an integer of 1 to 3.

Examples of the alkyl group include primary alkyl such as methyl, ethyl, propyl, octyl and 2-ethylhexyl, and the above-mentioned secondary or tertiary alkyl. Examples thereof include a methoxy group and an ethoxy group, and examples of the aryl group include a substituted or unsubstituted phenyl group and a naphthyl group. n is preferably 1. Ar represents a substituted or unsubstituted aryl group, preferably a substituted or unsubstituted phenyl group, and the substituent represents an alkyl group, an alkoxyl group, a halogen atom, a nitro group, a cyano group, an ester group, or the like. The substitution position of Ar is not particularly limited,
The o- or p-position, particularly the p-position, relative to the OH group is preferred.

The triarylamine compound is a compound having a parent structure (preferably a triphenylamine structure) in a part of the molecule, and is preferably a compound represented by the above general formula (2).
It is a compound represented by (5).

In the general formula (2), R ₃ represents a substituted or unsubstituted phenyl group, and R ₄ represents a hydrogen atom or a substituted or unsubstituted phenyl group. As a substituent, an alkyl group,
Alkoxyl group, halogen atom, nitro group, cyano group,
And an ester group. R ₅ , R ₆ , and R ₇ are substituents or substituents directly introduced into the triphenylamine matrix, and represent an alkyl group, an alkoxyl group, a halogen atom, or a hydrogen atom, and m is 1 to 3.

In the general formula (3), Z is preferably 5
A group of atoms necessary to form a membered or 6-membered ring, particularly preferably a substituted or unsubstituted methine chain, wherein the 5- or 6-membered ring may have a substituent. Note that Z does not always need to exist. R ₈ , R ₉ , R ₁₀ , and R _{11 each} represent an alkyl group, an alkoxyl group, a halogen atom, or a hydrogen atom;
Represents an integer.

In the general formula (4), k represents an integer of 0 or 1, R ₁₂ , R ₁₃ and R ₁₄ represent an alkyl group, an alkoxyl group, a halogen atom or a hydrogen atom, and m represents 1-3.
Represents an integer.

In the general formula (5), A or B represents a substituted or unsubstituted alkyl group or aryl group, respectively.
And B may combine with each other to form a ring. R ₁₅ , R
₁₆ and R ₁₇ represent an alkyl group, an alkoxyl group or a halogen atom or a hydrogen atom, and m represents an integer of 1 to 3. This ring is preferably a 5- to 6-membered nitrogen-containing heterocyclic ring,
The heterocyclic ring may form a condensed ring including a benzene ring and the like, and the heterocyclic ring may have a substituent.

Among these compounds, particularly preferred are compounds represented by the general formulas (2) to (4), which are known as compounds having high carrier mobility.

Specific examples of the compound of the present invention are shown below.

[0028]

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Various means can be considered for synthesizing the compound of the present invention represented by the general formula (1). Gordon
H. Stillson, David W.M. Sawye
r et al. (J. Amer. Chem. Soc. vol 6
7, 303 (1945)), isobutylene gas is blown into the corresponding phenol compound (unsubstituted at the 2- or 6-position) in the presence of an acid catalyst.

The route will be described specifically.

Synthesis Example (Synthesis of Compound P-1) 4-Phenylphenol 120
g was dispersed in 500 ml of toluene, and 3 ml of sulfuric acid was added.
At 0-60 ° C, isobutene (gas) is blown for 6 hours (1
00g) After completion of the reaction, the reaction mixture was diluted with Troen, washed with alkali, and distilled under reduced pressure (145 to 150/2 mmHg) to obtain the desired product.

(130 g of white crystals, yield Y = 63%)
mp 101 ° C.) Next, the above general formulas (2) to (5)
Representative compounds represented by

[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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As described above, the general formula (1) used in the present invention
Are included in the concept of so-called hindered phenolic antioxidants. However, when this product was incorporated into an electrophotographic photoreceptor, in addition to the effect based on the antioxidant ability, an effect not seen in conventional antioxidants was observed.

That is, in general, even if a large amount of an organic compound is contained in a photoreceptor, even if the photoreceptor is harmless, the concentration of a charge transport material (CTM), which is one of the basic materials of the photosensitive material, is reduced. As a result, the sensitivity may be reduced, possibly due to the reduction. On the contrary, the aromatic substituted hindered phenol compound of the present invention hardly causes a decrease in sensitivity,
Rather, it is an excellent material that has a slight, but conversely, effect of increasing sensitivity.

This effect of increasing the sensitivity is remarkable when combined with a triphenylamine compound.

The photoreceptor to which the compound of the present invention is added is not particularly limited and is a known photoreceptor, that is, a negatively chargeable function-separable type photoreceptor, a single-layer photoreceptor, and a photoreceptor having a reverse layer structure which are widely used today Can also be added.

The charge generation material (CG) used in the present invention
There is no limitation on M), and known materials can be used. Examples thereof include azo pigments, phthalocyanine pigments, anthraquinone pigments, imidazole perylene pigments, anthranthrone pigments, and the like. The CGM and the charge transporting substance (CTM = hole transporting substance) used in the present invention can be dispersed or dissolved by a known binder to form a photoreceptor.

Examples of the binder include a polycarbonate resin, a polystyrene resin, a silicone resin, a polyester resin, and a polyamide resin.

The photoreceptor of the present invention may have an intermediate layer between the conductive support and the photosensitive layer for the purpose of adhesion and preventing the injection of electric charge from the conductive support.

As a material of the intermediate layer, a known polymer used for an adhesive or the like, for example, a polyamide resin, a polybutyral resin, a polyvinyl acetate resin or the like can be used. In addition, a condensate of a partial hydrolyzate of a metal alkoxide (for example, a zirconium alkoxide, a titanium alkoxide, or the like) known as a ceramic undercoat may be used.

The photoreceptor of the present invention can have a protective layer.

The hindered phenol compound of the present invention can be added to each layer of the photoreceptor. When added to the charge transport layer (CTL), the addition amount is 0.1 to 100% by weight, preferably 1 to 50% by weight based on CTM in the CTL.
It is.

When added to the protective layer (OCL), OC
It is 0.1 to 100% by weight, preferably 1 to 50% by weight, based on the binder resin in L.

[0050]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto.

Example A A polyamide resin (CM) was placed on an aluminum drum having an outer diameter of 80 mm.
30 g of 8000 (produced by Toray Co., Ltd.) was charged into a mixed solvent of 900 ml of methanol and 100 ml of butanol, and dissolved by heating at 50 ° C. After cooling the obtained solution to room temperature, it was applied onto the drum by dip coating to form a 0.5 μm thick intermediate layer.

Next, 5 g of polyvinyl butyral resin (S-LEC BX-L, manufactured by Sekisui Chemical) was dissolved in 1000 ml of methyl ethyl ketone, and the charge-generating substance (CGM-1) 10
g were mixed and dispersed for 10 hours using a sand mill.
The obtained dispersion was dip-coated on the intermediate layer to form a 0.5 μm
An m-thick charge generation layer (CGL) was formed. Next, 200 g of the charge transport material (2-3) and the polycarbonate resin (Z
280 g of Mitsubishi Gas Chemical Co., Ltd.) and 20 g of the compound of the present invention (P-1 to 4, P-8, P-9) were dissolved in dichloromethane, and the obtained solution was applied onto the CGL by dip coating to obtain a 25 μm thick film. A charge transport layer (CTL) of
The photosensitive member of this example was dried by heating at 0 ° C. for 1 hour.

Comparative Example Compound P-1 in Example A without antioxidant (01) and Compound P-1 having the same CTM concentration as in Example (0) except that a polycarbonate resin was added in place of the antioxidant (0)
2) A comparative photoreceptor was prepared in the same manner as in Example except that the compound of the present invention in Example was replaced with an existing antioxidant (A-1, H-1, H-2, AH-1). did.

Evaluation The photoconductors of Examples and Comparative Examples obtained as described above were modified so as to be able to measure the surface potential by using a copying machine (variable current and exposure of a corona charger and equipped with an electrometer). (Konica's U-Bix 4045 remodeled machine), and performed 10,000 actual shooting tests under high temperature and high humidity. Black paper potential (Vb), blank paper potential (Vw), and residual potential (Vb) at initial and after 10,000 copies. Potential (V
r) was measured.

For evaluation of image blur, a drum was separately prepared and exposed to a 5 ppm nitrogen dioxide atmosphere for 10 minutes. Then, it was quickly mounted on the above-mentioned copying machine and image evaluation was performed.

The evaluation criteria were as follows: ：: no blur was observed at all,
Δ: slight blurring was observed but the degree was not severe, and x: blurring was clearly observed.

[0057]

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[0058]

[Table 1]

The photosensitive member of the present invention has an excellent effect on image blur. On the other hand, the existing hindered phenolic antioxidants have an effect on stabilizing the surface potential in the repeated test, but have little effect on preventing blurring. It is slightly worse than that (it may be because the CTM concentration was reduced). The hindered amine compound has an effect on blurring, but the residual potential in the repeated test is remarkably increased. The compound having hindered amine and phenol in the same molecule (AH-1) is also effective against blurring and is a relatively well-balanced compound, but the increase in the residual potential exceeds the allowable limit.

On the contrary, the compounds of the present invention have no image blur and little change in potential upon repetition. Also, the initial sensitivity is sensitized rather than the additive-free one. This is an excellent property of the compounds of the present invention not found in other antioxidants.

Example B In Example A, it was found that the antioxidant of the present invention had a sensitizing effect. Therefore, an antioxidant is fixed to P-1 and C
A photoconductor similar to that of Example A was prepared by changing the type of TM, and the initial sensitivity was measured at normal temperature and normal humidity. CGM is the same but C
Since the sensitivity and chargeability differ depending on the TM, the current amount and exposure amount of corona charge are adjusted for each CTM based on the sample without antioxidant (each 01), and the initial black paper potential (V
b) 740 to 760 V, blank paper potential (Vw) 70 to 9
It was adjusted to be 0V.

The comparative samples have no antioxidant (each 01), those having the same CTM concentration as in the examples by adding a polycarbonate resin instead of the antioxidant (02 each), and those having a triphenylamine structure. CT not included
M (ED1) was produced.

[0063]

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[0064]

[Table 2]

The antioxidant of the present invention is obtained by using the CT
When combined with M, the sensitivity is clearly increased.
CTM (5-) in group (5), which also contains the hydrazone
3) also has a sensitivity similar to that of a sample in which the CTM concentration is not diluted with an antioxidant, and it is recognized that sensitization has occurred.

On the contrary, the hydrazone CT mentioned for comparison
In the sample using M (ED1), the sensitivity is such that it is understood that the CTM concentration was diluted with an antioxidant.

Example C 25 g of red pigment dibromance anthrone (described in the following Chemical Formula 14) as a charge generating substance, 75 g of compound (2-4) as a charge transporting substance, and a polycarbonate resin (Z200 Mitsubishi Gas Chemical Co., Ltd.) as a binder Made) 100
g. Compound (P-1) 5 of the present invention as an antioxidant
g, add dichloromethane and disperse in a ball mill.
A photoreceptor coating solution was prepared. The photoreceptor coating solution was coated on a polyester base on which aluminum was deposited to form a photoreceptor sample having a thickness of 25 μm.

[0068]

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Comparative Examples As comparative sample photoreceptors, those not containing an antioxidant and those to which (H-1) and (H-2), hindered phenol compounds other than the present invention, were added were prepared.

Evaluation An electrostatic tester (EPA8100, manufactured by Kawaguchi Electric Co., Ltd.) equipped with an ozone generator (Model 0-12, manufactured by Ozone Japan) and an ozone monitor (EG-2001, manufactured by Ebara Corporation) are prepared. Charged by corona discharge of +6 kV,
Leave for 5 seconds in the dark (potential at this time is initial potential V ₀ ),
The light was then applied to measure the decay of the surface potential. The amount of light until the potential is reduced by half is defined as sensitivity (E _1/2 ).

Next, ozone gas was introduced, and the concentration was 90 p.
After maintaining for 3 hours in the state of pm, the ozone gas was removed, and after leaving for 3 hours, the charging potential (V ₀ ′) was measured again. The properties are shown in Table 3 below.

[0072]

[Table 3]

As shown in Table 3, the photoreceptor to which the compound of the present invention has been added has a small change in the charging potential even after exposure to ozone, similarly to the negatively charged photoreceptor. It can be seen that it is superior to those to which hindered phenol compounds (H-1) and (H-2) other than the present invention are added. The reason why such a property is exhibited is not clear, but it is probably related to the fact that the phenyl group at the 4-position contributes to stabilization of the excited state of the phenol moiety. That is, it is considered that radicals generated from active ozone are more efficiently inactivated (quenched).

The compound of the present invention is effective not only for a function-separated type negatively charged photoreceptor but also for a single layer type positively charged photoreceptor, and the sensitivity is almost the same as that of the negatively charged photoreceptor.

[0075]

According to the present invention, it is possible to provide a high-sensitivity photoreceptor which is excellent in environmental resistance and ozone resistance and which gives a good image without a decrease in charging ability and sensitivity in repeated use. .

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Yoshizawa Konica Corporation, 2970 Ishikawacho, Hachioji-shi, Tokyo (72) Inventor Takeshi Shimoda 2970, Ishikawacho, Hachioji-shi, Tokyo Konica Corporation (72) Inventor Yoko Kitahara 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation

Claims (4)

[Claims] 1. An electrophotographic photoreceptor comprising a compound represented by the following general formula (1) and a triarylamine compound. Embedded image (Wherein, R ₁ represents a secondary or tertiary alkyl group, R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkoxyl group; n represents an integer of 1 to 3;
r represents a substituted or unsubstituted aryl group. ) 2. The electrophotographic photoreceptor according to claim 1, wherein Ar is a substituted or unsubstituted phenyl group. 3. The method according to claim 1, wherein the triarylamine compound is a triphenylamine compound.
The electrophotographic photosensitive member according to the above. 4. The electrophotographic photoreceptor according to claim 3, wherein said triarylamine compound is a compound represented by the following general formulas (2) to (5). Embedded image (Wherein, R ₃ is substituted, it represents an unsubstituted phenyl group, R ₄ represents a hydrogen atom, a substituted, unsubstituted phenyl group, R ₅ to R
₁₇ represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxyl group, m represents an integer of 1 to 3, A and B each represent a substituted or unsubstituted alkyl group or an aryl group, and A and B bind to each other To form a ring, Z
Represents a linking group, and k represents 0 or 1. )