JPS592050A - Electrophotographic receptor - Google Patents

Abstract

PURPOSE:To obtain a long-lived photoreceptor nondamaged against friction forces repeatedly exerted on the surface and high in mechanical strength, by dispersing fine alumina powder together with a photoconductive substance into a binder resin and forming a photoconductive layer on a conductive substrate. CONSTITUTION:A photosensitive liquid is prepared by dispersing 0.1-100pts.wt. fine alumina powder having <=5mum particle diameter and 10<6>-10<14>ohm.cm volume resistivity into 100pts.wt. electrically insulating known binder resin, together with an inorganic photoconductor, such as CdS, or an org. photoconductor, such as copper phthalocyanine, dispersed or dissolved in the resin. The conductive substrate is coated with this liquid, dried, hardened to obtain an electrophotographic receptor. The photoreceptor thus obtained does not undergo damages on the surface of the photosensitive layer, even when a large number of copies are continuously made in a high speed copying machine or the like, it has high mechanical strength and long useful life, and forms a sharp image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having improved abrasion resistance, that is, mechanical strength of a photosensitive layer.

Conventionally, photoconductive materials used in the photoconductive layer of electrophotographic photoreceptors include inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide, organic polymers such as polyvinylcarbazole, and organic materials such as phthalo/anine and perylene. Organic photoconductive materials such as pigments are known.

Among such photoconductive substances, organic photoconductive substances such as organic polymers and organic pigments can be dispersed or made compatible with the binder resin. A photoconductive layer can be easily prepared by applying a dissolved organic photoconductive substance onto a conductive substrate and drying it. However, on the other hand, the photoconductive layer produced in this manner generally has the disadvantage of low mechanical strength, although it depends on the binder resin used.

Many techniques for improving the mechanical strength of photoreceptors have been proposed in the past, and one prior art proposes the use of isodino-alkyd resin, which has strong mechanical strength, as a binder resin. However, in this case, although the hardness of the photoreceptor is considerably increased, it is generally brittle, which leaves problems in practical use. It is also known to use a resin made of a cured polymer with a high degree of crosslinking in place of the above resin, but this increases mechanical strength, but does not cause electrostatic charge.
It has the disadvantage that the charge is not easily removed during exposure, resulting in toner fog on copies.

Furthermore, in addition to selecting a binder resin that improves the mechanical strength of the photoreceptor, a protective layer of phosphor or fluorine is placed on the photoconductive layer in order to increase the mechanical strength of the photoreceptor surface. Techniques have also been proposed for providing a protective layer, but as mentioned above, charging and charge leakage during exposure become difficult, resulting in toner fog on copies, so the protective layer must be made as thin as possible. . However, when using a thin layer,
Another drawback is that it lacks durability and cannot maintain good characteristics at the initial stage of copying.

In recent years, as copying machines have become smaller and faster, a magnetic brush developing method has been adopted in the developing process, and a cleaning blade has tended to be used in the cleaning process to remove residual toner. However, in these devices, it is required to increase the mechanical strength of the surface of the photoreceptor since a sliding force is constantly applied to the surface of the photoreceptor by a magnetic brush or a cleaning blade.

The present inventors have found that when a layer of a composition in which a photoconductive substance is dispersed or compatible with a binder resin and further contains aluminum oxide fine powder is provided on a conductive substrate, It has been found that the mechanical strength of the photoreceptor can be improved without impairing the copying characteristics such as.

That is, an object of the present invention is to provide a photoreceptor with excellent mechanical strength that will not be damaged even when a rubbing force is repeatedly applied to the surface of the photoreceptor during continuous copying.

Normally, to make a photoreceptor in which a composition in which a photoconductive substance is dispersed or dissolved in a binder resin is provided on a conductive substrate,
In particular, electrophotographic properties and mechanical properties must be considered. Electrophotographic properties include sensitivity and charging properties, and depend on the type of binder resin and photoconductive substance and the blending ratio of the two, while mechanical properties include hardness, flexibility, etc. , it largely depends on the physical properties of the binder resin and the ratio of the binder resin in the composition.

Thus, in order to obtain a more suitable photoreceptor, it is necessary to combine the above-mentioned characteristics to a high degree.

For this reason, the binder resins used include saturated polyester resins, polyamide resins,
Acrylic resin, ethylene-vinyl acetate copolymer, ionically crosslinked olefin copolymer (ionomer), styrene-
Thermoplastic binders such as butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, etc. Thermosetting binders such as xylene resin, thermosetting acrylic resin, unsaturated polyester resin, bismaleimide resin, alkyd resin, etc. These electrically insulating resins have a volume of 1.1014 Ωcm or more when measured alone. It is desirable that the photoconductive material and the binder resin have electrical resistance, and the weight ratio of the photoconductive material and the binder resin generally ranges from 100:I to 100:1000, particularly from 100:2 to 100:00, to achieve optimum electrophotographic properties. Optimum values for individual photoconductive material and binder resin combinations are determined to provide a combination of mechanical properties.

An important feature of the present invention is that a composition comprising the above-mentioned optimal combination of a photoconductive substance and a binder resin, and a composition in which aluminum oxide fine powder is further dispersed or compatible with a conductive substrate. Preferably, the fine aluminum oxide powder has a particle size of 5 μm or less and a volume electrical resistivity of 10 to 10 Ωcm to a composition comprising a combination of the photoconductive substance and a binder resin. The purpose is to disperse or dissolve the binder resin in an amount of 0.1 to 100 parts by weight per 100 parts by weight of the binder resin.

As is clear from the examples described below, it is possible to improve the mechanical strength without using the acid mentioned above.

Although the exact reason for this has not yet been fully elucidated, the reason for improving the mechanical strength of the photoreceptor is that aluminum oxide fine powder acts as an aggregate in the photoreceptor layer. it is conceivable that.

That is, the aluminum oxide fine powder used in the present invention has a larger surface area per particle size than other fine powders with the same particle size, and the particles themselves have a large hardness.
The bonding force with the binder resin in the binder resin is large, and even when external pressure is applied to one photosensitive layer, the aluminum oxide and ram fine powder particles themselves are not destroyed. By distributing the pressure to the binder resin and also cooperating with the flexibility of the binder resin, it is possible to avoid concentration of force.

As a result, the above-mentioned problem that the conventional photoreceptor has increased hardness but is generally brittle can be solved. In addition, by including aluminum oxide fine powder in the photosensitive layer, the ratio of the binder resin in the photosensitive layer decreases, and as a result, the capacitance of the photosensitive layer itself decreases, causing charge to escape. This improves the image quality and can also solve the problem of toner fog on copies.

The aluminum oxide fine powder used in the present invention is generally referred to as V-type alumina, and is produced using the Bayer method, which involves firing aluminum hydroxide (AI(OH)3), or anhydrous aluminum chloride (A-type alumina). Obtained by high-temperature hydrolysis of Cl5).

Further, as the photoconductive substance used in the present invention, any known photoconductive material can be used as long as it is dispersible or compatible with the insulating binder resin.

Such photoconductive materials include, but are not limited to, inorganic photoconductive materials such as zinc oxide, titanium oxide, selenium, cadmium sulfide, non-metallic phthalocyanines, metallic copper phthalocyanines, bicarbonate, etc. zoimidazole pigment, perylene pigment, quinacridone pigment, indigoid pigment, violaho+) -N-acrylicphenothiazine,
HoIJ-N-(β-acryloxy-ethyl)-phenothiazine, poly-N-(2-acryloxypropyl)-fetch azine, poly-N-allylcarbazole, poly-N-2-acryloxy/- 2-methyl-
N-ethylcarno(sol, poly-N-(2-p-vinylpensoylethyl)-ruhasol, ho+)-N--
j Lopenylcarbazole, poly-N-2-methylacrylic-oxapropylcarbazole, poly-N-acryliccarbazole, poly-4-vinyl-p-(N-carbasol)toluene, poly(vinylanizal) These photoconductors These substances can be used alone or in combination of two or more.

These photoconductive substances can be used in the form of being sensitized with chemical sensitizers or spectral sensitizers that are known per se.

For example, when combined with an electron-donating photoconductive substance, it forms a complex and becomes an electron acceptor (θ1ec
Any Lewis acid that acts as a tron acceptor can be used as a chemical sensitizer.

The most suitable examples of Lewis acids are tri- or tetra-nitrofluorenones such as 2,4,7-) IJ nitrofluorenone, 2,4,5,7-tetranitrofluorenone.

In addition to the above-mentioned Lewis acids, nitro groups,
Suitable examples of the cyano group, norogen atom, and ketone group are as follows.

2-Bromo-5-nitro-benzoic acid 1,2-bromobenzoic acid, 2';'lolutriol-4-sulfonic acid, chlormaleic anhydride, 9-chloroacridine, 0-
Chlornitropenzole, chloracetophenone, 2-
Chlorcinnamic acid, 2-chloro-4-nitro-1-benzoic acid, 2-chloro-5-nitro-1-4E-zoic acid, a-
Chlor-6-nitro-1-7-niline, 5-chlornitrobenzo-5-sulfochloride, 4-chloro-3-nitro-1-benzoic acid, 4-chloro-2-oquine-benzoic acid, 4-chloro- 1-phenol-3-sulfonic acid,'
2-chloro-3-nitro-1-toluo-5-sulfonic acid, 4-chloro-3-nitro-penzole phosphoric acid, dibromosuccinic acid, 2-4-dichlorobenzoic acid, dibromaleic anhydride, 9.10. - sifuromanthracene,
■, 5-dichlornaphthalene, 1,8-dichlornaphthalene, 2,4-dinitro-1-chloro-naphthalene, 8
．． 4-dichloro-nitropenzole, 2, + 4
'-'Chloro-benzisatin, 2,6-cycloupenzaltehyde, hexabromnaphthalic anhydride, phthalic anhydride, t+z-1-cyan-benzanthrone,
/Anoacetic acid, 2-cyanocinnamic acid, 3-chloro-6-nitro-r-benzoic acid, mucochloric acid, mu↓l.lifueniclormethane, tetracrocyphthalic acid,
Tetrabromophthalic acid, tetraiodophthalic acid, tetracrocyphthalic anhydride, tetrabromophthalic anhydride-1
phosphoric acid, tetraiodophthalic anhydride, tetrabromophthalic acid monoethyl ester, tetrabromophthalic acid monoethyl ester, tetrabromophthalic acid monoethyl ester, iodoform, fumaric acid dinitrile, tetracyanethylene, S-)licyane-benzole ,1,5-di・
/annaphthalin, phthalic anhydride, 3,5-dinitrobenzoic acid, 3,5-dinitrobenzoic acid, 2,4-dinitro-1-benzoic acid, 2,4-dinitro-1-toluo-
-6-sulfonic acid, 2,6-sinitro-1-phenol-4-sulfonic acid, 1,3-dinitro-penzole,
4+4'-dinitro-biphenyl, 3-nitro-4-methoxybenzoic acid, 4-nitro-1-methyl-benzoic acid, 6-nitro-4-methyl-1-phenol-2-sulfonic acid, 2-nitropenzole sulfone acid, 3-nitro-2-oxy-1-benzoic acid, 2-nitro-1-phenol-4-sulfonic acid, 4-nitro-1-phenol-
2-sulfonic acid, 3-nitro-N-butyl-carbazole, 4-nitro-biphenyl, tetranitrofluorenone, 2.4.6-dolinitroaninol, 2.4-dinitro-1-chlornaphthalene, 1. 4-dinitro-naphthalene, 1, 5-dinitro-naphthalene, 1,8-dinitro-naphthalene, 2-nitrobenzoic acid, 3-21.
Mouthbenzoic acid, 4-nitrobenzoic acid, 3-nitro-4-ethoxy-benzoic acid, 3-nitro-2-cresol-5-
Sulfonic acid, 5-nitrobarbic acid, 4-droacenaphthene, 4-nitrobenzaldehyde, 4-ditrophenol, picric acid, picryl chloride, 2
, 4.7-11J=)0-fluorenone, S-trinitro-pentole, anthraquinone, anthraquinone-2
-carboxylic acid, anthraquinone-2-aldehyde, anthraquinone-2-sulfonic acid anilide, anthraquinone-2,7-disulfonic acid, anthraquinone-2,7-disulfonic acid bis-anilide, anthraquinone-2-sulfonic acid dimethylamide, acetic acid Naphthenequinone, anthraquinone-2-sulfonic acid-methylamide, acenaphthenequinone dichloride, benzoquinone-1,4,1゜2-
Benzanthraquinone, bromoanil, 1-chloro-4
-Nitro-anthuq-non, chloranil, 1-chloro-anthraquinone, chrysenequinone, thymoquinone, l
-chloro-2-methyl-anthraquinone, teuroquinone, 2. -7 Chlorquinone, I, 5-diphenogizoanthraquinone, 2,7-sinitroanthraquinone, l
, 5-dichloro-anthraquinone, 1,4-dimethyl-
anthraquinone, 2,5-dichloro-benzoquinone, 2
．． 3-dichloro-naphthoquinone-1,4,1,5-dichloro-anthraquinone, 1-methyl-4-chloro-anthraquinone, 2-methylanthraquinone, naphthoquinone-1,2, naphthoquinone-1,4, pen/tacenequinone,
Tetracene-7,12-quinone, 1,4-toluo-fi
vki/7.2,5.7', Io-tetrachloro-pyrenequinone.

The electron-donating photoconductor and the Lewis acid have a ratio of +00: 1
0 to +00: 250X% to 100 = 20 to 100:
A weight ratio of 200 may be used.

Spectral sensitizers include dye sensitizers known per se, such as rose bengal, eosin, erythrosin, tsuksin, bironin B10 to damin G1, pyomine, methyl violet, neutral red, astrophloquine, crystal violet, diacid cyanine. Green GWA, Methylene Blue, Patent Blue v1 Victoria Blue B1 Xylene Shea Tool FF,
Brilliant Bloom 1 Uranine, Full Fang Tsusein,
Tartrazine, 3-carboxymethyl-5-(3-ethyl-2(3)-benzo"thiazolidenorhodanine triethylamine salt, auramine, cetofrapidine-T
1 Bromfe 0.005 to 0.2% by weight, especially 0,
It is used in amounts such as OI to 0.1% by weight.

In the present invention, a charge transfer complex of an electron-donating polymeric photoconductor and a Lewis acid is combined with an inorganic or organic photoconductive pigment in a weight ratio of, for example, 1000:1 to 1000:500, and this combination is It can also be used as a conductive material.

In addition to the above-mentioned essential components, the photoreceptor of the present invention may contain any known additives or compounding agents, if desired. For example, such compounding agents include thickeners, thinners, anti-sagging agents, leveling agents, antifoaming agents, etc., which are known per se.

The photoreceptor of the present invention is prepared by preparing a coating composition by dissolving or dispersing a binder resin and a photoconductive substance in an organic solvent and further dispersing fine aluminum oxide powder. The photoreceptor for electrophotography is prepared by coating the photoreceptor on a plastic substrate and then drying it.

As an organic solvent for preparing the coating composition, aromatic hydrocarbon solvents such as trichloride, benzene, toluene, and xylene; cyclic ethers such as dioxane and tetrahydrofuran;
Ketones such as methyl ethyl ketone, methyl imbutyl ketone, zoclohexanone; alcohols such as guacetone alcohol, ethylene glycol, isobutyl ether; one type or tr of alicyclic hydrocarbons such as nclohexane;
i A combination of two or more types can be used. 2. The coating composition of the present invention generally preferably has a solid content concentration of 1 to 50 inches, particularly 5 to 30 inches, from the viewpoint of coating workability.

The above-mentioned conductive substrates include copper, aluminum, silver,
Foils or plates of tin, iron, etc. are used in the form of sheets or drums, or these metals are applied to plastic films in the form of a thin film by vacuum deposition, electroless plating, etc. used.

The photosensitive composition of the present invention generally has a solid content of 2 to 2
It can be applied on the substrate as a layer with a thickness of 0μ, especially 3 to 10μ.

As detailed above, the present invention provides a photoreceptor with excellent mechanical properties and electrophotographic properties. Further advantageous features of the invention will become apparent in the following examples.

Examples 1-5 A photosensitive solution was prepared according to the following recipe.

The drug weighed according to the above prescription was coated on the ultrasonic separation plate for 2 minutes using a wire bar, and then 10 minutes.
The resin was thermally cured at 0° C. for 1 hour to provide heat treatment. The thickness of the photosensitive layer after heat treatment was 20 μm.

The samples manufactured above were stored in a dark place for one day and night, and then electrophotographic characteristics were evaluated under the following conditions.

Measuring equipment -> Manufactured by Kawaguchi Electric However, the sensitivity was measured by half-attenuation exposure.

Next, as a copy test, we conducted a copy test using C-162 manufactured by Sanda Kogyo KK.
The photoreceptor of Example 4 was attached to a molding machine equipped with a polyurethane blade as a cleaning blade, and a printing durability test was conducted. As a result, even after copying 30,000 copies, there were no scratches on the surface of the photoconductor, and the image quality of the copies remained almost the same as the first copy, with good transfer and clear and beautiful image quality. Ta.

Furthermore, as a comparison, a test was conducted in exactly the same manner as above using the master of Comparative Example I, and as a result, after approximately 10,000 copies were made, countless scratches caused by the blade occurred on the surface of the photoreceptor. The flaws also appeared in the image quality of the copies, making them very difficult to see and unclear. Moreover, the amount of toner scraped off by the blade was considerably greater than when the same number of copies were made using the photoreceptor of the present invention, and it was also found that the transfer performance was inferior to that of the photoreceptor of the present invention.

Example 6 A photosensitive solution was prepared according to the following recipe.

The weighed chemicals according to the above formulation were placed in a ball mill and dispersed for 24 hours to obtain a photosensitive liquid. Next, apply a photosensitive solution to 80 μm.
Coating was performed on an aluminum plate using a wire bar, and the thickness of the photosensitive layer was set to 16 μm.

The samples prepared above were stored day and night in a dark place, and then electrophotographic characteristics were evaluated under the following conditions.

Measuring machine - Made by Kawaguchi Electric KK However, sensitivity was measured by half-attenuation exposure.

Next, as a copying test, a printing durability test was carried out using a DC-optical body manufactured by Sanda Kogyo KK. As a result, even after 10,000 copies were made, there were no scratches on the surface of the photoconductor, and the image quality of the copies remained almost the same as the first copy, with good transfer and clear, beautiful images. Ta.

Furthermore, for comparison, a test was conducted in exactly the same manner as above using the master of Comparative Example 2, and as a result, approximately a, o o
When o sheets are copied, a blade is placed on the surface of the photoreceptor:
Numerous scratches occurred, and these scratches also appeared in the image quality of the copies, making them very difficult to see and having an unclear image quality.

Claims (4)

[Claims] (1) An electrophotographic photoreceptor characterized in that a layer of a composition in which a photoconductive substance and fine aluminum oxide powder are dispersed or dissolved in a binder resin is provided on a conductive substrate. (2) The electrophotographic photoreceptor according to claim 1, wherein the aluminum oxide fine powder is dispersed or dissolved in an amount of 0.1 to 100 parts by weight per 100 parts by weight of the binder resin. (3) The electrophotographic photoreceptor according to claim 1, wherein the fine aluminum oxide powder has a particle size of 5 μm or less. (4) The electrophotographic photoreceptor according to claim 1, wherein the aluminum oxide fine powder has a volume electrical resistance of 10 to 1014 Ωcm.