JP2665803B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly to a laminated electrophotographic photoreceptor having a charge generation layer and a charge transport layer.

[Prior Art] Conventionally, inorganic electrophotographic photosensitive members having a photosensitive layer containing selenium, cadmium sulfide, zinc oxide or the like as a main component have been widely used as electrophotographic photosensitive members.

These are not always satisfactory in heat stability, moisture resistance, durability, and the like. In particular, selenium and cadmium sulfide are restricted in production and handling due to toxicity.

On the other hand, an electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductive compound as a main component has many advantages such as overcoming the above-mentioned disadvantages of an inorganic electrophotographic photosensitive member, and has recently attracted attention.

Examples of such an organic photoreceptor include a photoconductive polymer represented by poly-N-vinylcarbazole and a charge transfer complex formed from the photoconductive polymer and a Lewis acid such as 2,4,7-trinitro-9-fluorenone. An electrophotographic photoreceptor having a photosensitive layer containing as a main component has already been put to practical use.

However, this electrophotographic photoreceptor is not always satisfactory in sensitivity and durability.

On the other hand, a function-separated type electrophotographic photoreceptor in which the charge generation function and the charge transport function are shared by separate substances, respectively, brings a remarkable improvement in sensitivity and durability, which were disadvantages of the conventional organic electrophotographic photoreceptor. Was.

Such a function-separated electrophotographic photoreceptor has a wide material selection range for each of the charge generation material and the charge transport material.
It has an advantage that an electrophotographic photosensitive member having arbitrary characteristics can be relatively easily manufactured.

In particular, as electrophotographic photoreceptors are used not only in copiers but also in laser beam printers and LED printers in recent years, a function-separated type is required to set a spectral sensitivity range that matches the emission wavelength of the light source used. Is suitable.

As the charge generating substance, various azo pigments, phthalocyanine pigments, polycyclic quinone pigments, cyanine dyes, squaric acid dyes, pyrylium salt dyes, and the like are known.

Among them, phthalocyanine pigments are stable against heat and light,
It is known for exhibiting a deep blue color, and has recently attracted attention not only as a pigment but also as an organic material that can withstand practical use as an electronic material or a catalyst.

Numerous proposals have been made in the field of electrophotographic photoreceptors, including U.S. Pat. No. 3,816,118, which proposed the use of phthalocyanine pigments.

As a document relating to a high-sensitivity phthalocyanine for an electrophotographic photoreceptor, Japanese Unexamined Patent Publication No.
JP-A-146255, JP-A-62-119547 using dihalogenostin phthalocyanine, and JP-A-59-49544 using titanyloxyphthalocyanine.

By the way, as charge transport substances, hydrazone compounds, pyrazoline compounds, stilbene compounds, triarylmethane compounds, arylamine compounds and the like are known.

These compounds are required to be stable against light and heat, ozone generated by corona discharge,
It is stable against NOx, nitric acid, etc., exhibits high charge transport ability, and has high compatibility with organic solvents and binders.

Examples of the combination of the phthalocyanine pigment and the charge transport material described above include, for example, JP-A-56-128948,
57-146255, JP-A-58-123542, JP-A-60
JP-243660, JP-A-61-27549, JP-A-61-1
No. 09056, and the like.

Electrophotographic photoreceptors made of these combinations have large potential drawbacks in image characteristics, such as small potential fluctuations during repeated use, but image deterioration due to changes in the use environment. It has become.

[Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor having a charge generation layer and a charge transport layer, an electron having sufficient high sensitivity and flatness of spectral sensitivity in a laser diode oscillation wavelength region. An object of the present invention is to provide an electrophotographic photoreceptor in which a potential during repeated use is stably maintained, and which exhibits stable potential characteristics and image characteristics regardless of a use environment (temperature and humidity). .

[Means for Solving the Problems and Action] The present invention relates to an electrophotographic photoreceptor having at least two layers of a charge generation layer and a charge transport layer provided on a conductive support, wherein the charge generation layer has the following general formula The charge transport layer comprises a layer containing at least one phthalocyanine pigment represented by (I), and the charge transport layer has the following general formula (I)
It comprises an electrophotographic photoreceptor comprising a layer containing at least one of the fluorene compounds shown in I).

General formula In the formula, R ₁ represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group or a nitro group; m is an integer of 1, 2, 3 or 4; M represents a metal atom excluding an alkali metal; And M is not divalent, and when M is trivalent, Y represents a halogen atom, an alkyl group or an alkoxy group; n is an integer of 1;
Is tetravalent, Y represents an oxygen atom, a halogen atom, an alkyl group or an alkoxy group;
Is an integer of 1; when it is other than an oxygen atom, n is an integer of 2.

General formula In the formula, R ₂ and R ₃ represent an alkyl group, R ₄ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and R ₅ and R ₆ represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group .

More specifically, as the above group, an alkyl group is a group such as methyl, ethyl, propyl, or butyl, an alkoxy group is a group such as methoxy, ethoxy, or propoxy, an aralkyl group is a group such as benzyl or phenethyl, and an aryl group is phenyl. , Naphthyl and the like, and a halogen atom are a chlorine atom, a bromine atom, a fluorine atom and an iodine atom.

Metal atoms M include Ti, V, Cr, Fe, Cu, Zn, Ga, A
Selected from l, Pb, Ge, Sn, In, Co and the like.

Hereinafter, typical examples of the charge generating substance and the charge transporting substance used in the present invention will be described.

Examples of charge-generating substances are R ₁ , m,
By describing M, Y and n.

Basic type Charge transporting substance (fluorene compound represented by general formula (II)) T- (1) T- (2) T- (3) T- (4) T- (5) T- (6) T- (7) T- (8) T- (9) T- (10) T- (11) T- (12) T- (13) T- (14) T- (15) T- (16) T- (17) T- (18) T- (19) T- (20) T- (21) T- (22) T- (23) T- (24) Next, the electrophotographic photosensitive member of the present invention will be described in more detail.

The charge generation layer contains as many phthalocyanine pigments of the general formula (I) as possible in order to obtain a sufficient absorbance, and a thin film layer, for example 5 μm or less, in order to shorten the range of the generated charge carrier. , Preferably 0.01-1μ
It is desirable to form a thin film layer having a thickness of m.

The charge generation layer can be formed by dispersing the phthalocyanine pigment represented by the general formula (I) in a suitable binder and applying the resulting dispersion on a conductive support. Alternatively, a vapor deposition film can be formed by a vacuum vapor deposition apparatus. it can.

As a binder used when forming by coating, a wide range of insulating resins can be selected, and poly-N-
It can be selected from organic photoconductive polymers such as vinyl carbazole, polyvinyl anthracene and polyvinyl pyrene.

Preferably, polyvinyl butyral, polyarylate (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinyl pyridine, cellulose resin, polyurethane, epoxy resin , Casein, polyvinyl alcohol, polyvinyl pyrrolidone and the like.

The amount of the resin contained in the charge generation layer is at most 80% by weight, preferably at most 40% by weight.

The solvent for dissolving these resins differs depending on the type of the resin, and is preferably selected from the types that do not dissolve the charge transport layer or the undercoat layer.

Specifically, methanol, ethanol, alcohols such as isopropanol, acetone, methyl ethyl ketone, ketones such as cyclohexanone, N, N- dimethylformamide, N, amides such as N- dimethylacetamide, sulfoxides such as dimethyl sulfoxide, Tetrahydrofuran, dioxane, ethers such as ethylene glycol monomethyl ether, methyl acetate, esters such as ethyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, aliphatic halogenated hydrocarbons such as trichloroethylene or benzene,
Aromatic compounds such as toluene, xylene, ligroin, chlorobenzene, and dichlorobenzene can be used.

Examples of the coating method include dip coating, spray coating, spinner coating, bead coating, Meyer bar coating, blade coating, roller coating, and curtain coating.

Drying is preferably performed by touch drying at room temperature and then heating and drying. Heat drying in a temperature range of 30 to 200 ° C for 5 minutes to 2
Perform at rest or under blast for a time range.

The charge transport layer is electrically connected to the charge depletion layer, and has a function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. I have. At this time, the charge transport layer may be laminated on the charge generation layer, or may be laminated thereunder.

The charge transport layer is formed by dissolving a fluorene compound represented by the general formula (II) together with a suitable binder, and applying the resulting solution.

Examples of the binder include insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, and the like. Organic photoconductive polymers such as -N-vinylcarbazole, polyvinylanthracene and polyvinylpyrene are exemplified.

Since the charge transport layer has a limit for transporting the charge carrier, the thickness cannot be increased more than necessary. Generally, it is 5 to 35 μm, but a preferable range is 8 to 30 μm.
It is.

When forming the charge transport layer by coating, an appropriate coating method as described above can be employed.

An electrophotographic photosensitive member having a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive support.

As the conductive support, those having conductivity itself, for example, metals and alloys such as aluminum and aluminum alloys can be used. In addition, aluminum, aluminum alloys, indium oxide, tin oxide, indium tin oxide and the like can be used. A plastic having a layer in which an alloy or the like is formed by a vacuum deposition method, a conductive support in which conductive particles (e.g., carbon black, silver particles, etc.) are coated on the metal support with a suitable binder, The conductive particles also include a plastic or a conductive support impregnated in paper or a plastic having a conductive polymer.

An undercoat layer having a barrier function and an adhesive function may be provided between the conductive support and the photosensitive layer.

The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymer nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc. .

The thickness of the undercoat layer is 0.1 to 5 μm, preferably 0.5 to 3 μm.
m is appropriate.

The electrophotographic photoreceptor of the present invention, in addition to a copying machine, can fully utilize its performance by using a laser diode printer, and also an LED printer, a liquid crystal printer,
It can be widely used in electrophotographic applications such as laser plate making.

[Example] Example 1 An undercoat layer using a vinyl chloride-maleic anhydride-vinyl acetate polymer of 0.1 µm was formed on an aluminum plate.

Next, 5 g of the exemplified pigment P- (11) was added to cyclohexanone 95
2 ml of butyral resin (butyralization degree: 63 mol%, number average molecular weight: 20,000) was dissolved in ml, and the mixture was dispersed by a sand mill for 20 hours.

The thickness of this dispersion after drying on the undercoat layer is 0.4 μm.
The resultant was coated with a Meyer bar and dried to form a charge generation layer.

Next, 5 g of the exemplified fluorene compound T- (1) and bisphenol Z-type polycarbonate resin (viscosity average molecular weight 3
5 g was dissolved in 70 ml of chlorobenzene, and this was applied on a charge generating layer with a Meyer bar so that the film thickness after drying was 17 μm, and dried to form a charge transport layer.

 The manufactured electrophotographic photoconductor is referred to as photoconductor 1.

Photoreceptor 1 was subjected to a corona charging of -5.5 KV in a static manner using an electrostatic copying paper tester Model SP-428 (manufactured by Kawaguchi Electric Co., Ltd.), held for 1 second in a dark place, and irradiated with 2 lux halogen. Exposure was performed with a lamp, and the charging characteristics were measured.

As the charging characteristics, the surface potential (V ₀ ), the potential after dark decay for one second (V _D ), and the exposure (E 1/5) required to attenuate V _D to 1/5 were measured. The results are shown.

V ₀ : −715 V V _D : −703 V E 1/5: 0.48 lux · sec Further, the photosensitive member 1 is provided with a −5.6 KV corona charger, an exposure optical system, a developing device, a transfer charger, a neutralizing exposure optical system, and a cleaner. Paste it on the cylinder of the equipped electrophotographic copier,
The image characteristics were examined.

This copying machine is configured so that an image can be obtained on a transfer paper by driving a cylinder.

Image evaluation: Humidity 10%, temperature 5 ° C, humidity 50%, temperature 18
C., humidity 80%, and temperature 35.degree. C., respectively.

In each case, good images faithful to the original were obtained. This image showed no blurring or blurring of the image even on the 10,000th sheet, indicating that the photoreceptor 1 exhibited good image characteristics.

A change in sensitivity over a laser oscillation wavelength range of 770 to 800 nm of the photoconductor 1, Was calculated, it was found that ΔE = 0.27, which was extremely small.

Examples 2 to 20 By combining the exemplified pigments and the exemplified fluorene compounds, electrophotographic photosensitive members corresponding to Examples 2 to 20 were manufactured in the same manner as in Example 1, and the resulting photosensitive members were designated as 2 to 20, and E1 / 5 was measured. did.

Further, the photoconductors 2 to 20 were affixed to a cylinder of an electrophotographic copying machine equipped with a -5.6 KV corona charger, an exposure optical system, a developing device, a transfer charger, a charge removing exposure optical system and a cleaner. This copying machine is configured so that an image can be obtained on a transfer paper by driving a cylinder.

Using this copier, the initial bright portion (V _L ) and the dark portion potential (V _D ) were set to −200 V and −700 V, respectively, and the bright portion potential (V _L 10000) and the dark portion after 10,000 uses. were measured variation △ V _L and △ V _D of the potential (V _D 10000).

However, △ V _L and △ V _D is when the bright part region and the dark portion potential at the initial stage V _L 0 and V _D 0 respectively _{△ V L = [V L 10000} ] - [V L 0] △ V D = [V _D 10000]-[V _D 0].

 The results are shown.

Combination of the exemplified pigment and the exemplified fluorene compound Comparative Examples 1 to 6 Instead of the fluorene compound of Example 1, compounds H- (1), (H)-(2), H- (3) and H-
(4) An electrophotographic photoreceptor was manufactured in the same manner as in Example 1 except that H- (5) and H- (6) were used as the charge transporting material, and Comparative Photoreceptors 1 to 6 were prepared. It was measured.

Further, the amount of potential fluctuation was measured in exactly the same manner as in Example 2. The results are described below.

Comparative Examples 7 to 16 Charge transport materials H- (1), H- (2), H- (3),
The compounds of H- (4), H- (5), and H- (6) were combined with the charge-generating materials used in Examples 1, 6, 10, 11, 13 and 18 as described below. Electrophotographic photoreceptors were manufactured in the same manner as in Examples, and Comparative Photosensitive Nos. 7 to 16 were prepared.

With respect to this comparative photoreceptor, the charging characteristics and the amount of potential fluctuation were measured. The results are shown. Comparative Example Comparative Photoreceptor Illustrative Pigment Charge Transport Material 77 P- (11) H- (1) 88 P- (6) H- (6) 99 P- (6) H- (3) 10 10 P- (7) H- (5) 11 11 P- (10) H- (4) 12 11 P- (11) H- (3) 13 13 P- (11) H- (2) 14 14 P- (15 ) H- (1) 15 15 P- (19) H- (6) 16 16 P- (23) H- (2) From the above results, it can be seen that the electrophotographic photoreceptor of the present invention is excellent in sensitivity and repetition potential characteristics.

Examples 21 to 25 Each of the photoconductors 7, 10, 11, 14 and 17 was exposed to 120 ppm of ozone for 30 minutes.
After being exposed to the _three gases for one hour, the charging characteristics were measured in exactly the same manner as in Example 1. The results are shown.

Comparative Columns 17 to 21 Using Comparative Photoconductors 9, 11, 12, 14, and 15
The charging characteristics were measured in exactly the same manner as described above. The results are shown.

From the above results, it can be seen that the electrophotographic photosensitive member of the present invention is an extremely stable electrophotographic photosensitive member against oxidizing substances caused by corona charging such as ozone and nitric acid.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention has high sensitivity and flat spectral characteristics in the oscillation wavelength range of a laser diode by combining a specific charge generating substance and a specific charge transporting substance, It exhibits stable image characteristics in a photographic process and has a remarkable effect of being excellent in potential stability.

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor comprising at least two layers, a charge generation layer and a charge transport layer, provided on a conductive support, wherein the charge generation layer comprises a phthalocyanine pigment represented by the following general formula (I) as a charge generation substance: The charge transport layer comprises a layer containing at least one of the following general formula (I)
An electrophotographic photosensitive member comprising a layer containing at least one of the fluorene compounds represented by I). General formula In the formula, R ₁ represents a hydrogen atom, an alkyl group, a halogen atom, a cyano group or a nitro group; m is an integer of 1, 2, 3 or 4; M represents a metal atom except for an alkali metal; And M is not divalent, and when M is trivalent, Y represents a halogen atom, an alkyl group or an alkoxy group; n is an integer of 1;
Is tetravalent, Y represents an oxygen atom, a halogen atom, an alkyl group or an alkoxy group;
Is an integer of 1; when it is other than an oxygen atom, n is an integer of 2. General formula In the formula, R ₂ and R ₃ represent an alkyl group, R ₄ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and R ₅ and R ₆ represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group . 2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer comprises a layer containing at least one fluorene compound represented by the following general formula (III) as a charge transport material. General formula In the formula, R ₇ and R ₈ represent a methyl group or an ethyl group.