JP2923312B2 - Electrophotographic photoreceptor - Google Patents

Description

The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member.
The present invention relates to an electrophotographic photosensitive member suitable for use in an image forming apparatus such as a laser printer, a facsimile, and a digital copying machine using a laser diode having an infrared wavelength as a light source.

<Prior Art> In an image forming apparatus such as a copying machine using a so-called Carlson process, an electrophotographic photosensitive member having a photosensitive layer formed on a conductive base material is used.

Conventionally, as a photosensitive layer of an electrophotographic photosensitive member used for a laser printer, a facsimile, a digital copying machine, or the like using a laser diode of an infrared wavelength as a light source, an organic photosensitive layer mainly using a phthalocyanine compound as a charge generating agent is used. I was This is because the phthalocyanine-based compound has excellent sensitivity at an infrared wavelength of 780 nm. Above all, so-called x-type metal-free phthalocyanines having an x-type crystal form are widely used because they have an advantage of being excellent in stability and dispersibility.

<Problems to be Solved by the Invention> However, x-type metal-free phthalocyanine as a charge generating agent is excellent in stability and dispersibility, but has a disadvantage that sensitivity (carrier generation efficiency) is insufficient.

On the other hand, various proposals have conventionally been made for improving the sensitivity of the photoconductor. For example, Japanese Patent Application Laid-Open No. 57-13257 describes a photoconductor in which the photosensitive layer contains nitrophthalic anhydride as a sensitizer to increase the sensitivity, and Japanese Patent Application Laid-Open No. 63-55555 discloses There is described a photoconductor in which the sensitivity is increased by adding a compound such as p-benzoquinone, anthraquinone, 1,4-naphthoquinone, or monochloro-p-benzoquinone.

However, even the photoreceptors using these sensitizers did not have sufficient sensitivity.

The present invention has been made in view of the above problems, and provides an electrophotographic photoreceptor having a photosensitive layer containing a phthalocyanine-based compound such as x-type metal-free phthalocyanine, and having dramatically improved sensitivity. The purpose is to:

<Means and Actions for Solving the Problems> An electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a photosensitive layer containing a phthalocyanine-based charge generating material, wherein the photosensitive layer has the following general formula as a sensitizer: Or phthalic acid or a derivative thereof.

(In the formula, R ¹ is a hydroxyl group, an amino group, a lower alkoxy group or a cyano group, and R ² is an oxo group or an imino group.) Examples of the lower alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group. And alkoxy groups having 1 to 6 carbon atoms such as butoxy group, pentyloxy group and hexyloxy group.

Phthalic acid or a derivative thereof represented by the above general formula,
By adding this to the photosensitive layer, the sensitivity of the photoreceptor is significantly improved over other known sensitizers (nitrophthalic anhydride, p-benzoquinone, etc.). Although the reason is not clear, it is assumed that the reason is that the electron transport efficiency in the charge generation layer is improved.

The amount of the phthalic acid or derivative thereof to be added is usually 1 to 20 parts by weight per 100 parts by weight of the phthalocyanine compound. When the amount of phthalic acid or a derivative thereof is larger than this range, undissolved components remain and adversely affect the photosensitive layer. On the contrary, when it is smaller than this range, a high sensitizing effect cannot be obtained. Are not preferred.

As the phthalocyanine-based compound in the present invention,
Metal-free phthalocyanine, aluminum phthalocyanine, vanadium phthalocyanine, cadmium phthalocyanine, antimony phthalocyanine, chromium phthalocyanine, copper 4-phthalocyanine, germanium phthalocyanine, iron phthalocyanine, dialkyl phthalocyanine,
Tetramethyl phthalocyanine, tetraphenyl phthalocyanine, and the like, and the crystal form is α-type, β-type, γ-type,
Any type such as ε type, σ type, x type and τ type can be used. In particular, in the present invention, considering the stability and dispersibility, x
Preference is given to using type metal-free phthalocyanines.

Further, together with the phthalocyanine-based compound, other charge generating agents (for example, azo-based, bisazo-based compounds, phthalocyanine-based, indigo-based, triphenylmethane-based, sulene-based, toluidine-based, pyrazoline-based, quinacridone-based, and pyrrolopyrrole-based) are used. You may use together.

The photosensitive layer in the present invention is formed on the surface of a conductive substrate. The conductive substrate is formed in an appropriate shape such as a sheet shape or a drum shape according to the mechanism and structure of the image forming apparatus into which the photoconductor is incorporated. The conductive base material may be entirely made of a conductive material such as a metal, or the base material itself may be made of a material having no conductivity, and the surface thereof may be provided with conductivity.

Examples of the conductive material used for the conductive substrate having the former structure include, for example, aluminum or untreated aluminum whose surface is anodized, copper, tin, platinum,
Metal materials such as gold, silver, vanadium, molybdenum, chromium, titanium, nickel, stainless steel, and brass can be used.

On the other hand, as the latter structure, a thin film made of a conductive material such as the above-mentioned metals or aluminum iodide, tin oxide, or indium oxide is laminated on a surface of a synthetic resin substrate or a glass substrate, or is vacuum-deposited or wet-plated. Examples thereof include those having a structure laminated by a known film forming method such as a method.

The conductive substrate may be subjected to a surface treatment with a silane coupling agent, a titanium coupling agent, or the like, if necessary, so as to enhance the adhesion to the photosensitive layer.

The photosensitive layer according to the present invention includes a single-layer organic photosensitive layer containing a charge generator containing the phthalocyanine-based compound and a charge transport agent in the binder resin, and a charge generator in the binder resin. And a charge transport layer containing a charge transport agent in a binder resin. The stacking order of the charge generation layer and the charge transport layer in the stacked photosensitive layer can be appropriately determined as necessary.

Examples of the charge transport agent include tetracyanoethylene; a fluorenone compound; a nitro compound such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; a triphenylmethane compound; an oxadiazole compound; Styryl compounds such as (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; pyrazoline compounds; 1-1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3 Conjugated unsaturated compounds such as butadiene; hydrazone compounds such as 4- (N, N-diethylamino) benzaldehyde-N-diphenylhydrazone;
Indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds,
Nitrogen-containing cyclic compounds such as pyrazoline compounds and triazole compounds; condensed polycyclic compounds and the like. These charge transporting agents can be used alone or in combination of two or more.

As the binder resin, for example, a curable acrylic resin,
Alkyd resin, unsaturated polyester, diallyl phthalate resin, melamine resin, styrene resin, acrylic polymer, olefin polymer such as polyethylene, polyvinyl chloride, polyvinyl acetate, polyamide, polycarbonate, thermoplastic polyurethane, ketone resin, And polyvinyl butyral resin.

An antioxidant, a deterioration inhibitor such as an ultraviolet absorber, a plasticizer, and the like can be added to each of the single-layer type and the laminated type photosensitive layer.

The amount of the phthalocyanine-based compound (charge generating agent) added to the single-layer type photosensitive layer is 2 parts per 100 parts by weight of the binder resin.
Suitably, it is -20 parts by weight, preferably 3-15 parts by weight. Further, the addition amount of the phthalocyanine compound in the charge generation layer in the laminated photosensitive layer is suitably from 5 to 500 parts by weight, preferably from 10 to 250 parts by weight, based on 100 parts by weight of the binder.

The addition amount of the charge transporting agent in the single-layer type photosensitive layer is suitably from 40 to 200 parts by weight, preferably from 50 to 100 parts by weight, based on 100 parts by weight of the binder resin. The amount of the phthalocyanine compound in the charge generation layer of the laminated photosensitive layer is suitably 10 to 500 parts by weight, preferably 25 to 200 parts by weight, based on 100 parts by weight of the binder.

The thickness of the formed photosensitive layer is 10 to 50 μm in the case of a single layer type.
m, preferably about 15 to 25 μm. On the other hand, in the case of the stacked type, the thickness of the charge generation layer is 0.01 to 3
It is preferable that the charge transport layer has a thickness of about 2 to 100 μm, particularly about 5 to 30 μm.

The single-layer or laminated photosensitive layer is manufactured by preparing a coating solution for each layer containing the above-described components, applying the coating solution to the conductive substrate for each layer, and drying or curing. You.

Various solvents can be used for preparing the coating liquid depending on the components used. Examples thereof include aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene; and dichloromethane. Alcohols such as isopropyl alcohol; ethers such as dimethyl ether; ketones such as acetone and cyclohexanone; esters such as ethyl acetate; dimethylformamide; and various solvents such as dimethyl sulfoxide. Can be

The coating liquid can be prepared by a conventional method, for example, using a mixer, a ball mill, a paint shaker, a sand mill, an attritor, an ultrasonic disperser, or the like.

<Example> Hereinafter, the present invention will be described in more detail with reference to examples.

Examples 1-4 An aluminum drum (diameter 78 mm, length
344 mm), a coating liquid for forming a charge generation layer having the following composition was applied onto the aluminum drum, and dried with hot air at a temperature of 110 ° C. for 30 minutes to form a charge generation layer having a thickness of 0.3 μm. Table 1 shows the types and amounts a of the sensitizers used.

Then, on the surface of the charge generating layer, a coating solution for forming a charge transporting layer having the following composition is applied, and dried with hot air at a temperature of 110 ° C. for 30 minutes to form a charge transporting layer having a thickness of 18 μm. An electrophotographic photosensitive member having a layer was obtained.

Comparative Example 1 An electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that no sensitizer was added to the charge generation layer.

Comparative Examples 2 and 3 An electrophotographic photoreceptor was obtained in the same manner as in Example 1 except that sensitizers of the type shown in Table 1 were added in a prescribed amount a shown in Table 1 to the charge generating layer. Comparative Example 2 is a sensitizer disclosed in JP-A-63-55555, and Comparative Example 3 is a sensitizer disclosed in JP-A-57-132157.

Test The charging characteristics and the photosensitive characteristics of the electrophotographic photosensitive members obtained in each of the examples and comparative examples were examined under the following conditions.

Charging: Scorotron (750 V Zener diode) Inflow current: 300 μA Exposure light source: semiconductor laser (wavelength 780 nm) Exposure intensity: 1.4 μJ / cm ² Process speed: 136 mm / sec The test results are shown in Table 1. In the table, the V _d is the initial non-exposed portion potential after charging the electrophotographic photoreceptor, V _l represents the initial exposure area potential after exposure, respectively, also V _d1000 1000
The non-exposed portion potential after repeated use is shown, and _Vl1000 represents the exposed portion potential after repeated use 1000 times.

 Table 1 shows the test results.

Formula (a): From Table 1, the electrophotographic photoreceptors obtained in Examples 1 to 4 are:
Compared with the electrophotographic photoreceptors of Comparative Example 1 to which no sensitizer was added and the electrophotographic photoreceptors of Comparative Examples 2 and 3 to which known sensitizers were added, the sensitivity was remarkably improved, and excellent charging was achieved. It can be seen that the film has characteristics and photosensitive characteristics.

<Effects of the Invention> As described above, in the electrophotographic photoreceptor of the present invention, a specific phthalic acid or a derivative thereof is added as a sensitizer to a photosensitive layer containing a phthalocyanine-based compound. There is an effect that the sensitivity of the photosensitive layer at the wavelength is dramatically improved.

Continuation of front page (56) References JP-A-3-35247 (JP, A) JP-A-61-156132 (JP, A) JP-A-54-147839 (JP, A) JP-A-62-100759 (JP, A) , A) JP-A-55-9558 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 5/09

Claims (2)

(57) [Claims] 1. An electrophotographic photoreceptor having a photosensitive layer containing a phthalocyanine-based charge generating material, wherein the photosensitive layer contains a charge generating agent containing a phthalocyanine-based compound and a charge transporting agent in a binder resin. Mold, or a charge generation layer in a binder resin, and a laminate type comprising a charge transport layer containing a charge transport agent in the binder resin, wherein the photosensitive layer is a phthalate represented by the following general formula as a sensitizer: 1 to 20 parts by weight of the acid or its derivative with respect to 100 parts by weight of the phthalocyanine compound.
An electrophotographic photoreceptor characterized by containing by weight. (In the formula, R ¹ is a hydroxyl group, an amino group, a lower alkoxy group or a cyano group, and R ² is an oxo group.) 2. The electrophotographic photoreceptor according to claim 1, wherein said phthalocyanine compound is an X-type metal-free phthalocyanine.