JPH04136948A - Electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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.

[Conventional technology]

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 toxic 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 poor printing durability. However, efforts are still 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, for organic low-molecular photoconductive compounds, polymers with excellent film properties, flexibility, and adhesive properties can be selected as binders, making it easy to obtain photoreceptors with excellent mechanical properties. However, it has been difficult to find suitable compounds for making highly sensitive photoreceptors.

[Means to solve the problem]

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 arylamine compounds are suitable. Reached.

That is, the gist of the present invention resides in an electrophotographic photoreceptor characterized by having a photosensitive layer containing an arylamine compound represented by formula (I) on a conductive support.

(In the formula, Ar' and Ar2 each represent an aryl group that may have a substituent, and these may be the same or different from each other. Ar3 represents an arylene group that may have a substituent. .

R1, R2, R3, R4, R5 and R6 are each a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group that may have a substituent, an alkoxy group that may have a substituent, and a represents an optionally substituted aralkyl group or an optionally substituted aryl group, which may be the same or different from each other. Further, B represents any one of the structures of the following general formulas [■] to (X).

(Vl) (■] (III) [■] 2Z [IX) (X) Ar' and Ar5 each represent an arylene group which may have a substituent, and these may be the same or different from each other. good.

R? , RI2. R15, R17, R summer 942
2 and R2S are each an alkyl group that may have a substituent, an aralkyl group that may have a substituent,
It represents an aryl group or an allyl group that may have a substituent, and these may be the same or different from each other.

Re, R9, R10, R11, R14, R weight #IB.

R2° 71 (21, R23, RZ4. R26 and RZ7 are each a hydrogen atom, a hydroxyl group, a halogen atom,
It represents an alkyl group that may have a substituent or an alkoxy group that may have a substituent, and these may be the same or different.

Further, R'3 represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an allyl group. However, RI2 and R13 may be combined to form a ring containing a nitrogen atom. ) Hereinafter, the present invention will be described in detail. The electrophotographic photoreceptor of the present invention has the above-mentioned -
Contains an arylamine compound represented by formula (1).

In the above formula, ^rl and Ar2 each represent an aryl group such as a phenyl group, a naphthyl group, an anthracenyl group, or a pyrenyl group, and these may be the same or different from each other, with a phenyl group being particularly preferred.

Ar' represents an arylene group such as a phenylene group, a naphthylene group, an anthracenylene group, and a phenylene group is particularly preferable.

R1, RZ, R3, R4, R5 and R6 are each a hydrogen atom; a hydroxyl group; a halogen atom such as a chlorine atom, a bromine atom, an iodine atom; a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, etc. Alkyl group; alkoxy group such as methoxy group, ethoxy group, butoxy group; aralkyl group such as benzyl group, naphthylmethyl group, phenethyl group; or aryl group such as phenyl group, naphthyl group, anthracenyl group; They may be the same or different, and a hydrogen atom and a methyl group are particularly preferred.

Further, B represents any one of the structures represented by formulas (II) to (X) above, but the structure represented by formula (II) is preferred, and most preferably R7 is an ethyl group, and R6 and R9
A structure in which is a hydrogen atom is preferred.

Ar' and Ar5 each represent an arylene group such as a phenylene group, a naphthylene group, an anthracenylene group,
These groups may be the same or different from each other, and a phenylene group is particularly preferred.

R7, R12, RIs, RI'J, Ru9.
R22 and R25 each represent an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, or a hexyl group; an aralkyl group such as a benzyl group, a naphthylmethyl group, or a phenethyl group; a phenyl group, a naphthyl group, an anthracenyl group, etc. represents an aryl group; or an allyl group, and these are
They may be the same or different from each other (in particular, methyl groups,
Lower alkyl groups such as ethyl group and benzyl group are preferred.

Re, R9, R10, R11, R14, Ru6.
R.I.B.

R2° 'fJt1. RZ3. R24, R26 and R''!, respectively, a hydrogen atom; a hydroxyl group; a halogen atom such as a chlorine atom, a bromine atom, an iodine atom; a methyl group,
It represents an alkyl group such as an ethyl group, a propyl group, a butyl group, a hexyl group; or an alkoxy group such as a methoxy group, an ethoxy group, a butoxy group, and these may be the same or different from each other, and in particular, a hydrogen atom, a methyl group, etc. is preferred.

Moreover, Ru3 represents an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group; an aralkyl group such as a hensyl group, a naphthylmethyl group, or a phenethyl group; or an allyl group; in particular, a methyl group, Lower alkyl groups such as ethyl group and benzyl group are preferred.

Furthermore, the aryl group represented by Ar' and Ar'', the arylene group represented by ^r3, the alkyl group, alkoxy group, and arylene group represented by aralkyl in R1, RZ, R3R4゜R5, and R6, R7, R12, Rls,
R17R19. R22 and R2! 'alkyl groups, aralkyl groups, and aryl groups, Re ,
R'l, RIOR II, R 14,
R16, R18, R20, R21, R
21.

R24. The alkyl group and alkoxy group in R26 and Ruff, and the alkyl group and aralkyl group in Ru3 may have a substituent.

Substituents include hydroxyl; halogen atoms such as chlorine, bromine and iodine; alkyl groups such as methyl, ethyl, propyl, butyl and hexyl; methoxy,
Alkoxy groups such as ethoxy groups and butoxy groups; allyl groups;
Aralkyl groups such as benzyl group, naphthylmethyl group, phenethyl group; Aryloxy groups such as phenoxy group, triloxy group; Aryl alkoxy groups such as benzyloxy group, phenethyloxy group; Aryl groups such as phenyl group, naphthyl group; styryl arylvinyl groups such as naphthylvinyl groups; dialkylamino groups such as dimethylamino and diethylamino groups; diarylamino groups such as diphenylamino and dinaphthylamino groups; dibenzylamino groups,
Examples include diheterocyclic amino groups such as diethylamino groups and diarylamino groups; diallylamino groups, and di-substituted amino groups in which substituents of the above amino groups are combined.

However, R'2 and RI3 are each derived from the above-mentioned substituents and are also included in the present invention if they are divalent substituents forming a ring. Examples of such groups include pyrrolidyl groups, piperidyl groups, and morpholino groups.

The above-mentioned amine compound represented by formula (I) can be produced using a known method.

Preferred manufacturing methods include, for example, the following methods (A) to (D).

(A) Method of condensation by reaction of raw material alcohol and ketone body, and then reaction of carbonyl group (B) Method of condensation by reaction of raw material ketone body and aldehyde body to synthesize chalcone, Method for reacting heavy bonds and carbonyl groups (C) Triarylamine as a raw material and R CI! , -C-C-X (R, R': g substituent, X
: After acylation by a free-sol Tarafluor reaction with a halogen atom), the other raw material, an aldehyde or ketone body, is condensed by a Wittig reaction to react with a double bond and a carbonyl group (D) Raw material The aldehyde body or ketone body and X-C
The olefin is condensed by Wittig reaction with I-X' (R: substituent, x, X': halogen atom), and then double bond reaction is performed, and then the other raw material, aldehyde or , a method in which the Wittig reaction with the ketone body is carried out again, and then a double bond reaction is carried out. Although several production methods have been shown above, it goes without saying that
The present invention is not limited only to these manufacturing methods.

To explain (A) of the above production method in detail, first, as shown in the reaction formula below, - formula (X I :l and [Xn
) (in the formula, r1.8r2+ Ar3.B, R2R
3, R5 and R6 have the same meaning as in general formula CI). The same applies to the following formulas. ), the alcohol compound and the ketone compound are reacted with a basic catalyst such as sodium hydroxide or potassium hydroxide in a known organic solvent that is inert to the reaction with xylene or the like, to form the formula (XI[
A compound represented by I) is obtained.

(XI) (XII) (Xlll) Next, the ketone moiety of general formula (XIII) is reacted, but it can be roughly divided into two reactions: reduction reaction and nucleophilic reaction to the ketone moiety.
It can be divided into

Reduction reactions can be further divided into two types: a reaction in which a ketone is converted into a secondary alcohol, and a reaction in which a ketone is directly converted into a methylene group.

First, for the reaction of converting a ketone into a secondary alcohol, a compound represented by formula (XII[) is mixed with lithium aluminum hydride, By using a reducing agent such as sodium borohydride, a compound represented by formula (1) is obtained.

Next, for a reaction in which a ketone is directly converted into a methylene group, the compound represented by the formula (XI) is reacted in ethanol water with Raney nickel as a catalyst, or sodium borohydride and trifluoride are reacted in tetrahydrofuran. React with boronic acid ether complex,
By reacting trifluoroacetic acid with sodium borohydride in methylene chloride, a compound of formula CI) is obtained.

Next, regarding the nucleophilic reaction to the ketone moiety, the formula (Xl
By reacting the compound represented by ll) with a Grignard reagent, an organometallic reagent, etc. in a known organic solvent inert to the reaction such as diethyl ether or tetrahydrofuran,
- A compound represented by formula [I] is obtained.

( XI .

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

- The arylamine compound represented by 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 an arylamine compound in the binder and, if necessary, a dye or electron-withdrawing compound as a sensitizer, and an arylamine compound containing photoconductive particles that generate charge carriers with extremely high efficiency when absorbing light. A photosensitive layer in which a compound is added in a binder, a charge transfer layer made of an arylamine compound and a binder, and a charge generation layer made of photoconductive particles that generate charge carriers with extremely high efficiency when absorbing light, or a charge generation layer made of photoconductive particles and a binder. Examples include photosensitive layers laminated with.

In these photosensitive layers, a known hydrazone compound or stilbene compound having excellent performance as an organic photoconductor may be mixed together with the arylamine compound represented by formula (1).

In the present invention, when the arylamine compound represented by the above 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 low. It is possible to obtain a photoreceptor that is small and has excellent durability with little variation in surface potential, decrease in sensitivity, accumulation of residual potential, etc. when used repeatedly.

The electrophotographic photoreceptor of the present invention is prepared according to the conventional method using the above-mentioned formula (
Photoconductive particles, sensitizer dyes, and electron-withdrawing compounds that generate charge carriers with extremely high efficiency when the arylamine compound represented by 1) is dissolved in a suitable solvent together with a binder and absorb light as necessary. , 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 having a thickness of usually several μm to several tens of μm. 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 coated on the charge ordering layer, or the charge generation layer is coated 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; esters such as ethyl acetate, methyl formate, and methyl cellosolve acetate Examples include solvents that dissolve arylamine compounds such as chlorinated hydrocarbons such as digloroethane and chloroborum. Of course, it is necessary to select one that dissolves the binder from among these. In addition, binders include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic esters, methacrylic esters, butadiene, polyvinyl acecool, polycarbonate, polyester, polysulfone, polyphenylene oxide, and polyurethane. , cellulose ether, cellulose ether, phonoxy resin, silicon resin, epoxy resin, and various other polymers that are compatible with styrenic compounds. The amount of binder used is usually 0.5 to 30 times the weight of the arylamine compound, preferably 0.7 to 10 times the weight of the arylamine compound.
The range is twice 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 upon absorption of light include inorganic photoconductive particles such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, cadmium sulfide, and amorphous silicon; metal-containing phthalocyanine, and perinone pigments. , 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, biryllium salts, thiapyrylium salts, and benzobyrylium salts. Examples of electron-withdrawing compounds that form charge transfer complexes with arylamine compounds include chloranil, 2,3-dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2 - Quinones such as chloroanthraquinone and phenanthrenequinone; aldehydes such as 4-nitrobenzaldehyde; 9-benzoylanthracene, indanedione, 3,5-dinitrobenzophenone, 2,4°7-dolinitrofluorenone, 2,4,5 Ketones such as .7 tetranitrofluorenone, 3.3', 5.5'tetranitrobenzophenone; acid anhydrides such as phthalic anhydride, 4-chloronaphthalic anhydride; tetracyanoethylene, terephthalalmalononitrile, 9- An-1-lyl methylidenemalononitrile, 4-nitrobenzalmalononitrile,
Cyano compounds such as 4-(p-nitrobenzoyloxy)penzalmalononitrile; 3-benzalphthalide, 3-(
α-cyano-p-nitrobenzal)phthalide, 3-(α
Examples include electron-withdrawing compounds such as phthalides such as -cyano-p-nitrobenzal)-4,5,6,7-tetrachlorophthalide.

Furthermore, the photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a known plasticizer in order to improve film formability, flexibility, and mechanical strength. For this purpose, examples of the plasticizer added to the coating solution include phthalic esters, phosphoric esters, epoxy compounds, chlorinated paraffins, chlorinated aliphatic esters, and aromatic compounds such as methylnaphthalene.

When using an arylamine compound as a charge transfer medium in the charge transfer layer, the coating liquid may have the composition described above, but photoconductive particles, dyes, electron-withdrawing compounds, etc. may be excluded (or a small amount may be added). In this case, the charge generation layer may be a coating liquid obtained by dissolving or dispersing the above-mentioned photoconductive particles in a solvent such as a binder polymer, an organic photoconductive substance, a dye, an electron-withdrawing compound, etc. as necessary. Examples include a thin layer formed by coating and drying, or a layer formed by forming the photoconductive particles into a film 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.

〔Effect of the invention〕

The electrophotographic photoreceptor of the present invention has extremely high sensitivity over the entire visible light region or semiconductor laser wavelength range, and does not decrease in sensitivity even in the short wavelength region of 400 to 500 nm, where conventional organic photoreceptors had low sensitivity. In addition, the residual potential that causes fogging is small, and in particular, there is little optical fatigue, so the accumulation of residual potential due to repeated use and fluctuations in surface potential and sensitivity are small, resulting in excellent durability.

〔Example〕

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 it exceeds the gist thereof. In addition, "parts" in the examples indicate "parts by weight."

Production example 1 4-acetyltriphenylamine 3.3g methyl-N-
2.6 g of ethylcarbazole C21 (S) heated and dissolved, then 0.7 g of powdered KOH at 110 °C.
was added, and then stirred for 1 hour while heating under reflux. after that,
Allow to cool, then add 20 mI of water to the reaction system! By adding , extracting and purifying using conventional methods, a brown oily substance 36
9g was obtained. This compound was found to be a carbonyl compound represented by the following structural formula by the following elemental analysis, mass spectrometry, and infrared absorption spectrum measurement.

(Elemental analysis value) As C3sH3°N20 (Mass spectrometry measurement result) C3s11i. As N20 MW=494M” −
494 g was obtained.

This compound was found to be an arylamine compound represented by the following structural formula by the following elemental analysis, mass spectrometry, and infrared absorption spectrum measurement (Figure 1).

(Elemental analysis value) C3,■3□N2 Production Example 2 3.8g of the carbonyl compound synthesized in Production Example 2 was added to tetrahydrofuran 76n+I! , and 0.6 g of sodium borohydride and 3.3 g of boron trifluoride-diethyl ether complex were added in this order at room temperature, and then reacted at the same temperature for 15 hours. Then, 50 m of water was added to the reaction system under water cooling.
1 and further extracted and purified by conventional methods to obtain colorless oil 2.3 (mass spectrometry measurement result) as C3sH812Nz MW=480M''=480 Example 1 1.4 parts of bisazo pigment having the above structure and polyvinyl butyral resin (#6000/C manufactured by Denki Kagaku Kogyo Co., Ltd.)
) and 0.7 parts of phenoxy resin (manufactured by Union Carbide Co., Ltd., registered trademark PKHH) were dispersed in 44 parts of methyl ethyl ketone and 15 parts of 4-methoxy-4-methylpankanone-2 using a sand grinder. 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.
/m2 with a wire bar and then dried to form a charge generation layer.

On top of this, the arylamine compound 8 produced in Production Example 2
A coating solution prepared by dissolving 100 parts of polycarbonate and 100 parts of polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd., registered trademark Niepilon E2000) in 900 parts of dioxane was applied and dried to form a charge transfer layer with a thickness of 20 μm.

Regarding the electrophotographic photoreceptor having the photosensitive layer composed of two layers thus obtained, the sensitivity, that is, the half-decrease exposure amount (El/2
) was measured and 1. It was O1ux-sec.

For the half-decreased exposure, first set the photoreceptor to -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 1/2 of the initial surface potential.

Example 2 A photoreceptor was prepared in the same manner as in Example 1 using a bisazo pigment represented by the following structural formula in place of the bisazo pigment used in Example 1, and the sensitivity was adjusted in the same manner as in Example 1. When measured, it was 1.81 ux-sec.

Example 3 Instead of the arylamine compound used in Example 1, an arylamine compound shown in Table 1 below, which was synthesized in the same manner as in Production Example 2, was used. The sensitivity of the electrophotographic photoreceptor obtained using the bisazo pigment used is shown in the table below.

[Brief explanation of drawings]

FIG. 1 shows an infrared absorption spectrum of the arylamine compound obtained in Production Example 2. Applicant Mitsubishi Kasei Corporation

Claims (1)

[Claims] (1) An electrophotographic photoreceptor comprising a photosensitive layer containing an arylamine compound represented by the general formula [I] on a conductive support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...[I] (In the formula, Ar^1 and Ar^2 each represent an aryl group that may have a substituent, and these may be the same or different from each other. Ar^3 represents an arylene group which may have a substituent. R^1, R^2, R^3, R^4, R^5 and R^6
are a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or a substituent, respectively. represents an aryl group which may have , and these may be the same or different from each other. Moreover, B represents any one of the structures of the following general formulas [II] to [X]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼, [II] [III] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, [IV] [V] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc.▼, [VI] [VII] ▲There are mathematical formulas, chemical formulas, tables, etc.▼, [VIII] ▲There are mathematical formulas, chemical formulas, tables, etc.▼, [IX] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [X] Ar^4 and Ar^5 each represent an arylene group which may have a substituent, and these may be the same or different from each other. R^7, R^1^2, R^1^5, R^1^7, R^1
^9, R^2^2 and R^2^5 each represent an alkyl group which may have a substituent, an aralkyl group which may have a substituent, and an aralkyl group which may have a substituent. It represents an aryl group or an allyl group, and these may be the same or different from each other. R^8, R^9, R^1^0, R^1^1, R^1^4
, R^1^6, R^1^8, R^2^0, R^2^1,
R^2^3, R^2^4, R^2^6 and R^2^7
each represents a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group which may have a substituent, or an alkoxy group which may have a substituent, and these may be the same or different. Further, R^1^3 represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an allyl group. However, R^1^2 and R^1^3 may be combined to form a ring containing a nitrogen atom. )