JP2636274B2 - Organic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic laminated photoreceptor having at least a charge generation layer and a charge transport layer on a substrate.

[Prior art and its problems] Conventionally, as a photoreceptor used in an electrophotographic apparatus or the like,
As a photosensitive material for forming a photoconductive layer, an inorganic photoconductive material such as selenium, zinc oxide, titanium oxide, and cadmium sulfide, or an organic photoconductive material has been used.

However, many of the above-mentioned inorganic photoconductive materials are generally highly toxic, have problems in moisture resistance and the like, and have many drawbacks.

On the other hand, when an organic photoconductive material is used,
Although excellent in lightness and price, sufficient sensitivity was not yet obtained, and there were problems in durability, stability against environmental changes, and the like.

For this reason, in recent years, a stacked photoreceptor in which the functions of charge generation and charge transport are separated has been proposed, and as a result, the disadvantages of the conventional photoreceptor using an organic photoconductive material have been significantly improved, A photoreceptor using an organic photoconductive material has been put to practical use and is rapidly making progress.

Such a laminated photoreceptor generally has a configuration in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate such as aluminum, an aluminum alloy, or copper.

In these laminated photoreceptors, basic properties such as charge retention, high sensitivity, repetition stability, dielectric breakdown resistance, abrasion resistance, durability, moisture resistance, transferability, cleaning properties, storage stability, etc. In recent years, it has been required to have high image reliability and repetition stability even during reversal phenomena, since it is also used for laser printers. .

Here, in the case of a conventional laminated photoreceptor, particularly in the case where the charge generation layer is formed by a dispersion film in which a pigment is dispersed in a resin, the charge generation layer has an adhesive property to the substrate, a coating property, and a charge injection from the substrate. There was a problem in various points such as.

Such a problem is largely caused by the conductive substrate itself, and it is necessary to improve defects on the substrate, charge injection properties, and adhesion.

In addition, Al-Mn based materials such as A3003 alloy or Al-Mg
-When a conventional organic laminated photoreceptor using a Mn-based material is used for a reader printer or laser printer and an image is formed by a reversal development method, partial discharge at the conductive substrate interface or from the conductive substrate Injection of the electric charge caused white spots in solid black portions and minute black spots in blank paper portions.

As a countermeasure against such a problem, Japanese Patent Application Laid-Open No. 58-3075
In JP-A-58-95744 and JP-A-58-95744, there are disclosed photoreceptors in which an undercoat layer is formed on a conductive substrate, and JP-A-58-14841 and JP-A-59-41360. JP-A-61-140947 proposes a photoconductor in which an aluminum support used as a conductive substrate is anodized.

Here, when the undercoat layer is formed on the conductive substrate as described above, various properties are required for the undercoat layer. For example, if the electric resistance of the undercoat layer is high, the undercoat layer is formed even after discharge. Since the potential remains in the layer and the so-called residual potential becomes high and fogging occurs in the image, the condition is that the electric resistance is low.

However, the undercoat layer disclosed in JP-A-58-30757 and JP-A-58-95744 has an electric resistance that is greatly affected by external environmental changes, particularly changes in atmospheric humidity.
There has been a problem that fogging occurs at low humidity.

For this reason, the thickness of the resin film forming the undercoat layer is made extremely thin, or a conductive powder such as a metal powder is dispersed in the resin as necessary to reduce the electric resistance. However, reducing the thickness of the resin layer has the disadvantage that the performance as an undercoat layer is not sufficient, while, in the undercoat layer in which metal powder is dispersed, metal particles are rough,
There is a disadvantage that the surface property of the undercoat layer is reduced.

Further, in the case of such a stacked type photoreceptor, it was not very effective in suppressing minute black spots generated in a blank portion when the reversal phenomenon was caused by using a laser printer.

On the other hand, in the case of a conductive substrate obtained by subjecting an aluminum support to alumite treatment, the cost is increased due to the alumite treatment, and impurities and the like are mixed into the substrate by this treatment, and black spots are generated on a white paper portion. Had the problem of adversely affecting

Japanese Patent Application Laid-Open Nos. 59-193463, 60-28662, and 59-212845 disclose that an aluminum substrate containing impurities such as iron, manganese, and magnesium contains a silicon atom. 1 shows a photoreceptor having a photoconductive layer containing an amorphous material as a base material.

However, the photoreceptor shown here is manufactured by a method such as plasma CVD using an amorphous material having a silicon atom as a base,
Since the photoconductive layer is formed on the surface of the aluminum base, the adhesion between the base and the photoconductive layer is poor, and fine streaks on the base surface cause white streak-like image noise or light interference. There has been a problem that development noise is very likely to occur due to the phenomenon.

For this reason, in this photoreceptor, it is necessary to use a high-purity aluminum substrate, which increases the cost and deteriorates the machinability, and it is necessary to roughen the surface. In addition, there is another problem that a material that is stable under conditions such as high temperature and high vacuum must be used.

The present invention has been made in view of the circumstances described above, and in an organic laminated photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated on an aluminum substrate, the characteristics of the aluminum substrate are improved, and the machinability and the charge generation layer are improved. It is an object of the present invention to provide a photoreceptor having excellent electrophotographic characteristics such as charge retention in addition to adhesiveness.

[Means and Actions for Solving the Problems] The present invention relates to an organic laminated photoreceptor having at least a charge generation layer and a charge transport layer formed on an aluminum substrate. An aluminum alloy containing 0.3% by weight of iron, 0.3% by weight or less of iron, 0.5 to 5% by weight of magnesium, and a total amount of other metals of 1.5% by weight or less was used. .

As described above, when an aluminum alloy in which silicon or the like is mixed into an aluminum substrate is used, a barrier against injection of carriers from the aluminum substrate to the charge generation layer or the like is increased, and a decrease in charging ability due to the injection of carriers is prevented. .

In addition, by using the aluminum substrate made of the above-described aluminum alloy, the occurrence of black spots, which is particularly problematic in a reader printer, a laser printer, or the like that performs reversal development, can be suppressed.

Further, by mixing silicon or magnesium, the machinability of the aluminum substrate is improved.

Here, the amount of silicon mixed into the aluminum substrate is
The content of 0.05 to 1% by weight means that if the content is less than 0.05% by weight, the strength and workability of the aluminum substrate are reduced.
If the content is more than the weight%, black spots may occur during the reversal phenomenon.

Further, the reason why the amount of magnesium in the aluminum base is set to 0.5 to 5% by weight is that if the amount is less than 0.5% by weight, the machinability is reduced, and irregularities are generated at the interface of the aluminum base, which causes partial discharge. If the content is more than 5% by weight, corrosion resistance becomes insufficient and dark attenuation increases.

Further, the reason why the amount of iron in the aluminum base is set to 0.3% by weight or less is that if a large amount of iron is contained, iron hardly forms a solid solution with aluminum and causes partial discharge.

Further, the reason why the total amount of other metals contained is 1.5% by weight or less is that when a large amount of copper, manganese, or the like is mixed, charge injection from an aluminum substrate is likely to occur.

And such an aluminum base is manufactured by a usual method. For example, a cylinder made of an aluminum alloy composed of the above components, by front hot extrusion or back hot extrusion, or after forming by a method such as cold instead of hot, mirror cutting with a diamond tool, or It can be obtained by rough surface cutting with a polygonal cutting tool or roughening treatment with a compound, buff, or the like.
The aluminum substrate may be subjected to a surface treatment such as an alumite treatment or an etching treatment, and in particular, the alumite treatment exhibits good characteristics.

Then, a charge generation layer and a charge transport layer are formed on such an aluminum substrate to obtain an organic laminated photoreceptor according to the present invention.

Here, when forming the charge generation layer, as a charge generation material, bisazo pigment, triarylmethane dye, thiazine dye, oxazine dye, xanthene dye, cyanine dye, styryl dye, pyrylium dye It is possible to use organic substances such as azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarylium pigments, and phthalocyanine pigments. it can. In addition, even if it is something other than this,
Any material that absorbs light and generates charge carriers with extremely high efficiency can be used.

Then, a charge-generating material as described above is added to a solution obtained by dissolving an appropriate binder resin in an appropriate solvent at a ratio of 10 to 200 parts by weight with respect to 100 parts by weight of the binder resin. Disperse by mill, sand mill, roll mill, etc.
This solution is applied to the surface of the aluminum substrate in a thickness of 0.1 to 1 μm.
Coating and drying to form a charge generation layer.

In forming the charge transport layer, an electron-donating substance comprising a derivative such as pyrazoline, triphenylmethane, oxadiazole, carbazole, hydrazone, styryl, imidazole, toninitrofluorenone,
A substance having a charge transporting property, such as an electron accepting substance such as tetranitroxanthone, tetracyanoethylene, and tetracyanoquinodimethane, is dissolved together with a resin having a film-forming property, applied 5 to 30 μm, and dried. Form.

Here, as the binder resin used for forming the charge generation layer and the like, use is made of a thermoplastic resin, a thermosetting resin, a photocurable resin, a photoconductive resin, or the like, which is electrically insulating and known per se. Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, and ion-crosslinked olefin copolymers ( (Ionomer), styrene-butadiene block copolymer, polyarylate, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, thermoplastic binder such as styrene resin, epoxy resin, urethane resin, silicone resin, phenol resin,
Examples include thermosetting binders such as melamine resins, xylene resins, alkyd resins, and thermosetting acrylic resins, photocurable resins, and photoconductive resins such as poly-N-vinylcarbazole, polyvinylpyrene, and polyvinylanthracene.

These can be used alone or in combination. It is desirable that these electrically insulating resins have a volume resistivity of 1 × 10 ¹² Ω · cm or more when measured alone. More preferred are polyester resin, polycarbonate and acrylic resin.

Further, together with such a binder resin, plasticizers such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, O-terphenyl, chloranil, tetracyanoethylene, 2,4,7-trinitro-9
-Fluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5
Electron-withdrawing sensitizers such as dinitrobenzoic acid, and sensitizers such as methyl violet, rhodamine B, cyanine dyes, pyrylium salts, and thiapyrylium salts may be used.

Further, in the organic laminated photoreceptor according to the present invention,
If necessary, an adhesive layer, an intermediate layer, and a surface protective layer may be provided.

As a material used for the intermediate layer, a polymer such as polyimide, polyamide, nitrocellulose, polyvinyl butyral, or polyvinyl alcohol as it is, or a material in which a low-resistance compound such as tin oxide or indium oxide is dispersed, aluminum oxide, zinc oxide, oxide A deposited film of silicon or the like is suitable. This intermediate layer has a thickness of 1
It is desirable that it is not more than μm.

As a material used for the surface protective layer, a polymer such as an acrylic resin, a polyaryl resin, a polycarbonate resin, or a urethane resin as it is, or a material in which a low-resistance compound such as tin oxide or indium oxide is dispersed is suitable. Also, an organic plasma polymerized film can be used, and this organic plasma polymerized film can contain oxygen, nitrogen, halogen, and atoms of Groups III and V of the periodic table, if necessary.

 The thickness of the surface protective layer is desirably 5 μm or less.

[Effects of the Invention] As described above, in the organic laminated photoreceptor according to the present invention, 0.05 to 1% by weight of silicon and 0.3% by weight or less of iron are added to the aluminum substrate on which the charge generation layer and the charge transport layer are laminated. And an alloy containing 0.5 to 5% by weight of magnesium and a total amount of other metals of 1.5% by weight or less. The coatability has been improved, the partial discharge at the interface of the aluminum substrate has been reduced, and the charge injection from the aluminum substrate has also been suppressed. As a result, good electrophotographic properties can be obtained.

EXAMPLES Next, specific examples of the present invention will be described, and comparative examples will be given to clarify that the examples of the present invention are superior.

Here, in each of the examples and comparative examples, when manufacturing the aluminum substrate in the organic laminated photoreceptor by cutting, a precision cutting lathe manufactured by Eguro Iron Works was used. The cylinder was set so as to have a negative rake angle of −20 ° with respect to the central angle of the cylinder for the aluminum substrate.

Then, on the rotating shaft flange of the lathe, let the aluminum alloy cylinder for each aluminum substrate be checked, spray white kerosene from the nozzle attached to the lathe, and suck the chips with the nozzle also attached to the lathe, With the above polygonal cutting tool, each aluminum alloy cylinder was cut under the cutting conditions of a peripheral speed of 650 m / min and a feed speed of 0.02 mm / rev to manufacture each aluminum base having an outer diameter of 80 mm.

Examples 1 and 2 In each of the examples 1 and 2, an aluminum substrate produced by cutting as described above was made of an aluminum substrate having the components shown in Table 1 below. used.

Then, a 1% methanol solution of polyamide resin (manufactured by Elvamide 8061 Dupont) was first applied to the surface of each of the aluminum substrates, and dried to form a 0.1 μm intermediate layer.

Next, when forming a charge generation layer on the intermediate layer, using a τ-type metal-free phthalocyanine as a charge generation material, 0.45 parts by weight of the τ-type metal-free phthalocyanine and 0.45 parts by weight of a polystyrene resin (molecular weight 40,000), in addition to the solvent of cyclohexanone 50 parts by weight, they were dispersed by a sand grinder, the dispersion was applied to a dry film thickness to the intermediate layer is 0.2 g / m ^2, which was dried intermediate layer To form a charge generation layer.

Next, in forming a charge transport layer on the charge generation layer thus formed, a styryl compound represented by the following chemical formula I was used as a charge transport material.

Then, 10 parts by weight of this styryl compound and 10 parts by weight of a polycarbonate resin (K-1300: manufactured by Teijin Chemicals) were added to 1,4
-Dissolve in 100 parts by weight of Geokin, apply this solution to the charge generating layer so that the dry film thickness becomes 20 μm, and dry to form a charge transport layer. Each was produced.

Comparative Examples 1 to 3 In order to compare with those of Examples 1 and 2, Comparative Examples 1 to 3
In each of the above, aluminum substrates having the components shown in Table 2 below were used.

An intermediate layer, a charge generation layer, and a charge transport layer were formed in the same manner as in Examples 1 and 2 except that such an aluminum substrate was used.
Were produced respectively.

Next, each of the laminated photoconductors of Examples 1 and 2 and Comparative Examples 1 to 3 manufactured as described above was used in a copying machine Ep-470Z manufactured by Minolta Camera Co., Ltd., and charged with corona. The half-exposure amount E required to set the initial surface potential V _o of each photoconductor to −750 V and to halve the initial surface voltage V _o of each photoconductor.
Half (1 × sec) and the dark decay rate DDR ₅ (%) of the initial surface potential when left in the dark for 5 seconds were measured. Also, while the initial surface potential V _o of each photoconductor -750 V, and the developing Baiyasu voltage Vb to -500 V, and black spots in the white paper portion of the image when obtained by reversal development, the black solid portion The white spots were evaluated. Further, the workability of each aluminum substrate used in Examples 1 and 2 and Comparative Examples 1 to 3 during cutting and applicability of a resin or the like during coating were also evaluated.

The results are summarized in Table 3 below. In the table, black spots on white paper portions during reversal development, white spots on solid black portions, workability during cutting, and applicability during coating were evaluated as ○ when good, and practically problematic. The case where there is no problem is indicated by △, and the case where there is a problem is indicated by ×.

As shown in the same table, those of Examples 1 and 2 were different from those of Comparative Example in that black spots on a blank portion during reversal development,
The white spots on the solid black portion were reduced, and the workability of the cutting line and the applicability at the time of coating were also good.

Examples 3 to 5 In Examples 3 to 5, the aluminum base used was composed of the components shown in Table 4 below.

Then, in Examples 3 and 4, these aluminum substrates were immersed in an electrolytic solution containing 15 vol% of sulfuric acid at a liquid temperature of 20 ± 1 ° C. to form an alumite layer on the surfaces of these aluminum substrates. This alumite layer had a barrier layer of about 200 ° and a porous layer of 7 μm. Thereafter, these aluminum substrates were treated with a nickel acetate aqueous solution (concentration 7).
% By weight) at 50 ° C. to seal the aluminum substrate.

On the other hand, in the case of Example 5, the aluminum substrate was used as it was without performing the alumite treatment as described above.

Next, in forming a charge generation layer on these aluminum substrates, a disazo compound represented by the following chemical formula II was used as a charge generation material.

Then, 0.45 parts by weight of this disazo compound and 0.45 parts by weight of a polyester resin (manufactured by Byron 200 Toyobo Co., Ltd.) were added to a solvent of 50 parts by weight of cyclohexanone, and these were dispersed by a sand grinder. Next, this dispersion was dried on each of the aluminum substrates described above to a dry film thickness of 0.
After coating to 3 g / m ² , this was dried to form a charge generation layer.

Next, in providing the charge transport layer on the charge generation layer thus formed, the same styryl compound shown below as the charge transport material used in Examples 1 and 2 was used. used.

Then, 10 parts by weight of this styryl compound and 10 parts by weight of a polyarylate resin (U-100: manufactured by Unitika Ltd.)
The solution was dissolved in 100 parts by weight of THF, and this solution was dried to a thickness of 20 μm.
Was applied on the above-mentioned charge generation layer, and dried to form a charge transport layer, thereby producing laminated photoconductors of Examples 3 to 5, respectively.

Comparative Example 4 In order to compare with those of Examples 3 to 5, in Comparative Example 4, the aluminum substrate used in Comparative Example 3 was used. The body was made.

Next, each of the laminated photoconductors of Examples 3 to 5 and Comparative Example 4 thus manufactured was used in a copying machine Ep-470Z manufactured by Minolta Camera Co., Ltd. in the same manner as described above. , Half-exposure E1 / 2 (1xsec), dark decay rate for each photoconductor
DDR ₅ (%) was measured, and black spots on white paper, black spots on solid black, workability during cutting, and applicability of resin and the like during coating were evaluated during reversal development.

These results are summarized in Table 5 below. Regarding black spots on white paper during reversal development, white spots on solid black, workability during cutting, and applicability during coating, the same as in the previous case: The case where there was no problem was indicated by △, and the case where there was a problem was indicated by ×.

Also in the present results, as shown in the same table, in the example, the number of black spots on a blank portion and the number of white spots on a solid black portion during reversal development were smaller than that of the comparative example. Was.

Further, in the present results, the half-life exposure amount and the dark decay rate of the example were generally lower than those of the comparative example, and the sensitivity and the charge retention ability were superior to those of the comparative example.

Claims (1)

(57) [Claims] An organic laminated photoreceptor comprising at least a charge generation layer and a charge transport layer formed on an aluminum substrate, wherein the aluminum substrate contains 0.05 to 1% by weight of silicon, 0.3% by weight or less of iron, 0.5-5% by weight
An organic laminated type photoreceptor comprising an aluminum alloy containing 1.5% by weight or less of a total amount of other metals contained.