JP3239143B2 - Electrophotographic photoreceptor - Google Patents

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, and more particularly, to an electrophotographic photosensitive member containing a specific compound in a photosensitive layer.

[0002]

2. Description of the Related Art Conventionally, inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been used as a photoconductive material of a photoreceptor used in an electrophotographic system.
Here, the term "electrophotographic method" generally means that a photoconductive photoreceptor is first charged in a dark place, for example, by corona discharge, and then subjected to image exposure to selectively dissipate the charge of only the exposed portion. An electrostatic latent image is obtained, and the latent image portion is developed and visualized with fine particles (toner) composed of a coloring material such as a dye or a pigment and a binder such as a polymer substance to form an image. This is one of the image forming methods used.

The basic characteristics required of a photoreceptor in such an electrophotographic method include (1) being able to be charged to an appropriate potential in a dark place, (2) being small in electric charge dissipation in a dark place, (3) Charges can be quickly dissipated by light irradiation.

[0004] The above-mentioned inorganic substances have many advantages and also have various disadvantages. For example, selenium, which is widely used at present, satisfies the above conditions (1) to (3), but the production conditions are difficult, the production cost is high, there is no flexibility, and the selenium is processed into a belt shape. It also has drawbacks in that it is difficult to handle, and is sensitive to heat and mechanical shocks, and requires careful handling. Cadmium sulfide and zinc oxide are used as photoreceptors by dispersing them in a resin as a binder.However, due to mechanical defects such as smoothness, hardness, tensile strength, and abrasion resistance, they are repeatedly used as they are. Can not be used.

In recent years, electrophotographic photoreceptors using various organic substances have been proposed to eliminate the disadvantages of these inorganic substances, and some of them have been put to practical use. For example, a photoreceptor comprising poly-N-vinylcarbazole and 2,4,7-trinitrofluoren-9-one (U.S. Pat.
84237), a photoreceptor obtained by sensitizing poly-N-vinylcarbazole with a pyrylium salt-based dye (described in JP-B-48-25658), and a photoreceptor containing an organic pigment as a main component (see JP-B-48-25658). JP-A-47-37543), a photoreceptor containing a eutectic complex composed of a dye and a resin as a main component (described in JP-A-47-10735), and dye-sensitized triphenylamine compound. (US Pat. No. 3,180,730), a photoreceptor using an amine derivative as a charge transport material (JP-A-57-195254), and poly-N-vinylcarbazole and an amine derivative as charge transport materials Photoreceptor used (Japanese Patent Laid-Open No. 58-11
55, a photoconductor using a benzidine compound among polyfunctional tertiary amine compounds as a photoconductive material (US Pat. No. 3,265,496, JP-B-39-11546, JP-A-53-27033). ). Although these photoreceptors have excellent properties and are considered to be of high practical value, in electrophotography, considering various requirements for photoreceptors, these requirements are still insufficient. In fact, it is not possible to obtain anything satisfying the above conditions.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photoreceptor which can solve the above-mentioned various disadvantages of the conventional photoreceptor and can sufficiently satisfy the conditions required in electrophotography. It is in. It is a further object of the present invention to provide an electrophotographic photoreceptor which is easy to manufacture, relatively inexpensive, and has excellent durability.

[0007]

According to the present invention, a photosensitive layer containing, as an active ingredient, at least one alkylpyrene compound represented by the following general formula 1 (general formula I) on a conductive support is provided. An electrophotographic photoreceptor characterized by having:

Embedded image ( Wherein , Ar is a heterocyclic group or N-carbazolylphenyl
The group and R are a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group, and n is 1 or 2. )

In the present invention, the alkylpyrene compound represented by the general formula (1) to be contained in the photosensitive layer is, for example, represented by the following general formula 2 (general formula (II))

Embedded image (Wherein, Ar, R and n are the same as described above).

In the general formula (I), Ar represents a monovalent or divalent heterocyclic group, and specific examples of the monovalent group include the following groups. Pyridyl group, pyrimidyl group, pyrazinyl group, triazinyl group, furyl group, pyrrolyl group, thienyl group, quinolyl group, coumarinyl group, benzofuranyl group, benzimidazolyl group, benzoxazolyl group, dibenzofuranyl group, benzothiophenyl group ,
Dibenzothiophenyl group, indolyl group, carbazolyl group, pyrazolyl group, imidazolyl group, oxazolyl group,
Isoxazolyl group, thiazolyl group, indazolyl group,
Benzothiazolyl group, pyridazinyl group, cinnolinyl group, quinazolinyl group, quinoxalyl group, phthalazinyl group, phthalazinedionyl group, chromonyl group , naphtholactonyl group, quinolonyl group, imidyl O-sulfobenzoate, imidyl maleate, naphthalidyl, benz Imidazolonyl group, benzoxazolonyl group, benzothiazolonyl group, benzothiazothonyl group, quinazolonyl group, quinoxaronyl group, phthalazonyl group, dioxopyrimidinyl group, pyridonyl group, isoquinolonyl group, isoquinolyl group, isothiazolyl group, benz Isoxazolyl group, benzisothiazolyl group, indazolonyl group, acridinyl group, acridonyl group, quinazolindionyl group,
Quinoxalinedionyl, benzoxazinedionyl, benzoxazinyl , naphthalimidyl, tetrahydrofuryl, tetrahydrothienyl, piperazino, piperazinyl, pyrrolidinyl, and the like.

The heterocyclic groups include those having the following substituents.

(1) halogen atom, cyano group, nitro group (2) alkyl group, preferably C ₁ -C _12, especially C ₁
To C ₈ , more preferably C _{1 to} C ₄ linear or branched alkyl groups, and these alkyl groups are furthermore fluorine, hydroxyl, cyano, C _{1 to} C ₄ alkoxy, phenyl or It may contain a phenyl group substituted by a halogen atom, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group. Specifically, a methyl group, an ethyl group,
n-propyl group, i-propyl group, t-butyl group, s-
Butyl group, n-butyl group, i-butyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-cyanoethyl group, 2-ethoxyethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, Examples include a 4-methylbenzyl group, a 4-methoxybenzyl group, a 4-phenylbenzyl group, and the like.

(3) alkoxy group (-OR ₁ ); R ₁ represents an alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, 2
-A cyanoethoxy group, a benzyloxy group, a 4-methylbenzyloxy group, a trifluoromethoxy group and the like.

(4) Aryloxy group: Examples of the aryl group include a phenyl group and a naphthyl group. This is C ₁
Alkoxy group -C _4, alkyl group, or a halogen atom C ₁ -C ₄ may contain a substituent group. Specifically, a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methylphenoxy group, a 4-methoxyphenoxy group, a 4-chlorophenoxy group, a 6-methyl-2
-Naphthyloxy group and the like.

(5) Alkyl mercapto group (-S
R ₁ ); R ₁ represents an alkyl group defined in (2). Specific examples include a methylthio group, an ethylthio group, a phenylthio group, and a p-methylphenylthio group.

[0015] Represents an alkyl group or an aryl group, and an aryl group
For example, phenyl group, biphenylyl group or naphthyl
And these include C₁~ C_FourAn alkoxy group of C
₁~ C_FourWith an alkyl group or a halogen atom as a substituent
May be contained. ) Specifically, amino group, diethylamino group, N-methyl
-N-phenylamino group, N, N-diphenylamino
Group, N, N-di (p-tolyl) amino group, dibenzyla
And a mino group.

(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.

In the general formulas (I) and (II), the alkyl group represented by R is the alkyl group described for the substituent of the heterocyclic group, and the aryl group is a phenyl group, biphenylyl group, naphthyl group or the like. .

Hereinafter, representative examples of the alkylpyrene compound represented by the general formula (I) will be shown.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

In the photoreceptor of the present invention, one or more of the above-mentioned alkylpyrene compounds are used in the photosensitive layer 2 (2 ', 2).
'', 2 '''' or 2 ''''), depending on the application of these alkylpyrene compounds, as shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4 or FIG. Can be used.

The photoreceptor shown in FIG. 1 has a conductive support 1 on which a photosensitive layer 2 comprising an alkylpyrene compound, a sensitizing dye and a binder (binder resin) is provided. The alkylpyrene compound here acts as a photoconductive substance,
The generation and transfer of charge carriers required for light decay are performed via alkylpyrene compounds. However, since the alkylpyrene compound has almost no absorption in the visible region of light, it is necessary to sensitize by adding a sensitizing dye having absorption in the visible region for the purpose of forming an image with visible light. is there.

The photosensitive member shown in FIG. 2 has a photosensitive layer 2 'in which a charge generating substance 3 is dispersed in a charge transporting medium 4 comprising an alkylpyrene compound and a binder on a conductive support 1. It is. The alkylpyrene compound here forms a charge transport medium with a binder (or a binder and a plasticizer), while the charge generating material 3 (a charge generating material such as an inorganic or organic pigment) generates a charge carrier. . In this case, the charge transport medium 4 is mainly responsible for receiving and transporting charge carriers generated by the charge generating substance 3. In this photoreceptor, the basic condition is that the charge generating substance and the alkylpyrene compound do not overlap in the absorption wavelength region mainly in the visible region. This is because it is necessary to transmit light to the surface of the charge generating material 3 in order to efficiently generate charge carriers in the charge generating material 3. The alkylpyrene compound represented by the general formula (I) has almost no absorption in the visible region, and generally absorbs light in the visible region, and is particularly effective when combined with the charge generation material 3 which generates a charge carrier. The feature is that it works as

The photosensitive member shown in FIG. 3 is a photosensitive layer 2 'comprising a conductive support 1 and a charge generating layer 5 mainly composed of a charge generating substance 3 and a charge transporting layer 4 containing an alkylpyrene compound. 'Is provided. In this photoreceptor, the light transmitted through the charge transport layer 4 reaches the charge generation layer 5 and charge carriers are generated in that region. On the other hand, the charge transport layer 4 receives injection of the charge carriers and transports them. The generation of charge carriers required for light attenuation is based on the charge generation material 3
The transport of the charge carriers is performed in the charge transport layer 4 (where an alkylpyrene compound mainly works). Such a mechanism is the same as that described for the photoconductor shown in FIG.

The photosensitive member in FIG.
And the charge transport layer 4 containing the alkylpyrene compound is reversed in the stacking order, and the mechanism of generation and transport of the charge carriers can be the same as described above. In this case, a protective layer 6 can be provided on the charge generation layer 5 in the fifth manner in consideration of mechanical strength.

In order to actually manufacture the photoreceptor of the present invention, FIG.
In the case of the photoreceptor shown in (1), one or two or more alkylpyrene compounds are dissolved in a solution in which a binder is dissolved, and a solution is prepared by adding a sensitizing dye thereto. What is necessary is just to apply | coat on top and dry, and to form the photosensitive layer 2.

The thickness of the photosensitive layer is 3 to 50 μm, preferably 5 to 20 μm. The amount of the alkylpyrene compound in the photosensitive layer 2 is 30 to 70% by weight, preferably about 5%.
The amount of the sensitizing dye in the photosensitive layer 2 is 0.1 to 5% by weight, preferably 0.5 to 3% by weight. Examples of sensitizing charges include triarylmethane dyes such as brilliant green, Victoria Blue B, methyl violet, crystal violet, and acid violet 6B, rhodamine B, rhodamine 6G, rhodamine G extra, eosin S, erythrosin, rose bengal, and fluorescein. Such as xanthene dyes, thiazine dyes such as methylene blue, cyanine dyes such as cyanine, 2,6-diphenyl-4- (N, N-dimethylaminophenyl) thiapyrylium perchlorate, and benzopyrylium salts (Japanese Patent Publication No. Sho 48) 25658)) and the like. These sensitizing dyes may be used alone or in combination of two or more.

Further, in order to produce the photoreceptor shown in FIG. 2, fine particles of the charge generating substance 3 are dispersed in a solution in which one or more alkylpyrene compounds and a binder are dissolved, and this is electrically conductive. Coated on a support 1 and dried to form a photosensitive layer 2
'May be formed.

The thickness of the photosensitive layer 2 'is 3 to 50 μm, preferably 5 to 20 μm. The amount of the alkylpyrene compound in the photosensitive layer 2 'is 10 to 95% by weight, preferably 30 to 90% by weight, and the amount of the charge generating substance 3 in the photosensitive layer 2' is 0.1 to 50% by weight. , Preferably 1 to 20% by weight. Examples of the charge generation material 3 include inorganic pigments such as selenium, selenium-tellurium, cadmium sulfide, cadmium sulphide-selenium, and α-silicon. (CI 21200), CI Acid Red 52 (CI 45100), CI Basic Red 3 (CI45210), an azo pigment having a carbazole skeleton (described in JP-A-53-95033),
Azo pigments having a distyrylbenzene skeleton (JP-A-53
JP-A-133445), azo pigments having a triphenylamine skeleton (described in JP-A-53-132347), azo pigments having a dibenzothiophene skeleton (described in JP-A-54-21728), oxadiazole Azo pigments having a skeleton (described in JP-A-54-12742), azo pigments having a fluorenone skeleton (described in JP-A-54-22834), and azo pigments having a bisstilbene skeleton (described in JP-A-54-22784) 17733), an azo pigment having a distyryloxadiazole skeleton (described in JP-A-54-2129), and an azo pigment having a distyrylcarbazole skeleton (described in JP-A-54-14).
Azo pigments such as C.I. Pigment Blue 16 (CI 74100), such as C.I.
(CI 73410), sea butt die (CI 7
3030), Argo Scarlet B (manufactured by Bayer AG), Indance Scarlet R
(Manufactured by Bayer AG) and the like. These charge generating substances may be used alone or in combination of two or more.

Further, in order to manufacture the photoreceptor shown in FIG. 3, a charge generating substance is vacuum-deposited on the conductive support 1 or more, or a suitable binder is prepared by dissolving a binder 3 if necessary. Coating and drying, and further, if necessary, surface finishing and film thickness adjustment by a method such as buffing, and the like.
Is formed, and a solution in which one or more alkylpyrene compounds and a binder are dissolved is applied thereon and dried to form the charge transport layer 4. Here, the charge generation layer 5
Are the same as those described in the description of the photosensitive layer 2 '.

The thickness of the charge generation layer 5 is 5 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer 4 is 3 to 50 μm.
μm, preferably 5 to 20 μm is suitable. In the type in which the charge generation layer 5 has the fine particles 3 of the charge generation layer material dispersed in a binder, the ratio of the fine particles 3 of the charge generation material to the charge generation layer 5 is preferably 10 to 95% by weight. Is about 50 to 90% by weight. The charge transport layer 4
Is 10 to 95% by weight, preferably 3% by weight.
0 to 90% by weight. In order to prepare the photoreceptor shown in FIG. 4, a solution in which an alkylpyrene compound and a binder are dissolved is applied on the conductive support 1 and dried to form the charge transport layer 4. The charge generation layer 5 may be formed by applying a dispersion of fine particles of the charge generation layer material in a solvent in which a binder is dissolved, if necessary, by a method such as spray coating and drying. The amount ratio of the charge generation layer or the charge transport layer is the same as that described in FIG. The photoreceptor shown in FIG. 5 can be prepared by further forming a protective layer 6 on the thus-obtained photoreceptor charge generation layer 5 by a method such as spray coating. As the resin used here, a binder described later can be used.

In the production of any of these photoconductors, a metal plate or a metal foil such as aluminum, a plastic film on which a metal such as aluminum is vapor-deposited, or a paper subjected to a conductive treatment is used for the conductive support 1. Can be Examples of the binder include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate; and vinyl polymers such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, and polyacrylamide. All insulating and adhesive resins can be used. If necessary, a plasticizer is added to the binder. Examples of such a plasticizer include halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, and dibutylphthalate.

Further, the photosensitive member obtained as described above may be provided with an adhesive layer or a barrier layer between the conductive support and the photosensitive layer, if necessary. Materials used for these layers include polyamide, nitrocellulose,
Aluminum oxide and the like, and the film thickness is preferably 1 μm or less. To make a copy using the photoreceptor of the present invention,
After the photosensitive surface is charged and exposed, development is performed and, if necessary, transfer to paper or the like. The photoreceptor of the present invention has excellent advantages such as high sensitivity and high flexibility.

[0032]

The present invention will be described below with reference to examples. In the following examples, all parts are parts by weight.

[Synthesis of Compound of General Formula (I)] [Compound No. Synthesis Example 2] Synthesis 1 of 1- [3- (9-ethylcarbazolyl)]-2- (1-pyrenyl) ethane
1.22 g (3.46 mmol) of-[3- (9-ethylcarbazolyl)]-2- (1-pyrenyl) ethylene are dissolved in 20 ml of tetrahydrofuran, and 0.12 g of activated carbon with 5% palladium is added. Under pressure, the inside of the reaction vessel was filled with hydrogen and shaken. After completion of the reaction, the reaction solution was filtered through Celite, and the filtrate was concentrated under reduced pressure to obtain a pale green powder. After drying this powder, it was subjected to column purification (carrier: silica gel, eluent: chloroform / n-hexane = (2/3) vol mixed solvent) to give 1.01 g of pale green powder (yield: 82.8).
%). Further, the obtained pale green powder is mixed with toluene / n
Recrystallized with a mixed solvent of -hexane to obtain colorless needle crystals.
-[3- (9-Ethylcarbazolyl)]-2- (1-pyrenyl) ethane was obtained. The melting point of the obtained compound is 19
6.0-197.5 ° C., and the elemental analysis value was C ₃₂ H ₂₅ N
It was as follows. C (%) H (%) N (%) Measured value 91.00 5.71 3.29 Measured value 90.74 5.95 3.31 Further, in the infrared absorption spectrum (KBr tablet method) of this compound, the raw material 1- [3- (9-Ethylcarbazolyl)]-2- (1-pyrenyl) ethylene was confirmed to have disappeared at 960 cm ^{-1 due} to a transolefin ^- based absorption peak. Other alkylpyrene compounds were synthesized in the same manner as described above.

Example 1 As a charge generating substance, 76 parts of P-1 shown in Table 6, 1260 parts of a 2% solution of polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.) in tetrahydrofuran and 3700 parts of tetrahydrofuran were ground and mixed in a ball mill. The obtained dispersion was applied on an aluminum surface of a conductive support made of a polyester base on which aluminum was deposited by using a doctor blade, and was naturally dried to form a charge generating layer having a thickness of about 1 μm. On the other hand, as the charge transport substance, Compound Specific Example No. 2 parts of an alkylpyrene compound of No. 8 and a polycarbonate resin (Panlite K1300, manufactured by Teijin Limited) 2
And 16 parts of tetrahydrofuran were mixed and dissolved to form a solution. The solution was applied onto the charge generating layer using a doctor blade, and then applied at 80 ° C. for 2 minutes and then at 120 ° C. for 5 minutes.
After drying for about 20 minutes, a charge transport layer having a thickness of about 20 μm was formed. 1 was created.

Examples 2 to 4 Except that the charge generating substance and the charge transporting substance (alkylpyrene compound) were changed to those shown in Table 6, the photosensitive member Nos. 2 to 4 were prepared.

[Table 6]

The photosensitive member No. Using a commercially available electrostatic copying paper tester (SP428, manufactured by KK Kawaguchi Denki Seisakusho) for 1-4, a corona discharge of -6 KV or +6 KV was performed for 20 seconds to charge the battery, and then left in a dark place for 20 seconds. The surface potential Vpo (volt) at that time was measured, and then a tungsten lamp light was applied so that the illuminance on the photoreceptor surface became 4.5 lux, and the surface potential was V
The time (seconds) required to reach 1/2 of the po is obtained, and the exposure amount E1
/ 2 (looks per second) was calculated. Table 7 shows the results.

After charging each of the above photoreceptors using a commercially available electrophotographic copying machine, the photosensitive members are irradiated with light through the original drawing to form an electrostatic latent image, and developed using a dry developer. When the obtained image (toner image) was electrostatically transferred onto plain paper and fixed, a clear transfer image was obtained. Similarly, when a wet type developer was used as the developer, a clear transfer image was obtained.

[Table 7]

[Effects] The photoreceptor of the present invention is excellent not only in photosensitivity, but also has high strength against heat and mechanical shock, and can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view enlarged in a thickness direction of an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a cross-sectional view enlarged in a thickness direction of the electrophotographic photosensitive member according to the present invention.

FIG. 3 is a cross-sectional view enlarged in a thickness direction of the electrophotographic photosensitive member according to the present invention.

FIG. 4 is a cross-sectional view enlarged in a thickness direction of the electrophotographic photosensitive member according to the present invention.

FIG. 5 is a cross-sectional view enlarged in a thickness direction of the electrophotographic photosensitive member according to the present invention.

[Description of Signs] 1... Conductive support 2, 2 ′, 2 ″, 2 ″ ″, 2 ″ ″ ″... Photosensitive layer 3... Charge generating substance 4. Generation layer 6 ... Protective layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomoyuki Shimada Ricoh Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo (56) References JP-A-4-117349 (JP, A) 4-230764 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 5/06 314-315

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer containing at least one alkylpyrene compound represented by the following general formula [1] as an active ingredient. Embedded image ( Wherein , Ar is a heterocyclic group or N-carbazolylphenyl
The group and R are a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group, and n is 1 or 2. )