JP3158815B2 - Dispersion type organic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor used for electrophotography, and more particularly, to a photoreceptor having a thick photosensitive layer, having excellent abrasion resistance and electrical characteristics, and having good image quality without roughness or image roughness. The present invention relates to a photoreceptor capable of forming an image.

[0002]

2. Description of the Related Art Conventionally, in a photoreceptor used for electrophotography and the like, inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide have been known as materials constituting a photosensitive layer. These inorganic photoconductive materials have many advantages, for example, less charge dissipation in a dark place, or the ability to quickly dissipate charge by light irradiation, but have the following various disadvantages. ing. For example,
Selenium-based photoconductors are expensive to manufacture and are susceptible to heat and mechanical shock, so care must be taken when handling them. In addition, cadmium sulfide photoconductors do not provide stable sensitivity in humid environments, and dyes added as sensitizers cause charge deterioration due to corona charging and photobleaching due to exposure. Has the disadvantage that it cannot be provided. Further, these photoconductors have a problem in terms of safety.

On the other hand, the use of various organic photoconductive polymers such as polyvinyl carbazole for forming the photosensitive layer has been studied as a material constituting the photosensitive layer. These polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film formability and lightness, but still have sufficient sensitivity, durability and stability due to environmental changes. It was inferior to the conductive material.

In recent years, various researches and developments have been made in order to solve the above-mentioned drawbacks of these photoconductors, and the charge generation function and the charge transport function of the photoconductive function are respectively separated from each other. A function-separated type organic photoreceptor of the laminated type or the dispersed type was developed. Normally, the photosensitive layer of the layered function-separated type photoreceptor is configured by laminating a charge generation layer containing an organic charge generation material and a charge transport layer containing an organic charge transport material and a binder resin, The photosensitive layer of the dispersed-type function-separated type photoconductor is composed of a layer in which an organic charge generation material and an organic charge transport material in a binder resin are dispersed.

[0005] Such a function-separated type organic photoreceptor has a wide selection range of materials, and can combine the best materials in electrophotographic characteristics such as charging characteristics, sensitivity, residual potential, and repetition characteristics. A high-performance photoconductor can be provided. Further, since it can be produced by coating, extremely high productivity and an inexpensive photoreceptor can be provided, and the photosensitive wavelength region can be freely controlled by appropriately selecting the charge generating material.

In particular, a dispersed-type function-separated type photoreceptor can be used as a positively charged photoreceptor. Positively charged photoreceptors have attracted attention because they generate less ozone than negatively charged photoreceptors and are advantageous for the environment.

However, the above-mentioned organic photoreceptors generally have lower mechanical strength than inorganic photoreceptors and are inferior in durability, and are practically used in an apparatus such as friction with toner or paper and friction with a cleaning member. The above load causes the photosensitive layer to be worn and the film thickness to be reduced. The amount of film loss due to wear is
Although it differs depending on the material and the process, it is usually about 0.2 to 1 μm in a 10,000-sheet copy process. Further, a decrease in the film thickness causes a decrease in chargeability. If this decrease exceeds an allowable range, the photoreceptor reaches its end of life, resulting in poor press life.

Therefore, in order to improve the durability and extend the life of the photosensitive member, it has been studied to make the photosensitive layer thicker than before in the dispersion type photosensitive member.

[0009]

However, simply,
When the thickness of the photosensitive layer is greatly increased, there is a problem that charge is accumulated in the photosensitive layer due to repeated use, a remarkable rise in residual potential, and image disorder is caused due to a decrease in charging performance. .

Accordingly, the present invention has solved the above-mentioned problems,
Even if the thickness of the photosensitive layer is significantly increased from the conventionally used thickness in the vicinity of 10 to 20 μm and is increased to 30 μm or more, preferably 35 μm to 60 μm, the electrical characteristics do not deteriorate upon repeated use. , The rise in residual potential is small,
It is an object of the present invention to provide a high sensitivity dispersion-type and function-separation type organic photoreceptor.

[0011]

SUMMARY OF THE INVENTION The present invention has a thickness of 10 to 1 mm.
With a barrier layer of 2,000 mm and a porous layer having a thickness of 1 to 10 μm.
And the electrically conductive substrate having alumite layers formed of, and a photosensitive layer having a thickness of 30~60μm obtained by dispersing an organic charge-generating material and an organic charge-transporting material in a binder resin, wherein the alumite layer is nickel acetate or fluoride reduction are sealing treatment by nickel, Lee <br/> impedance of sealing treatment Eloxal layer is 85 ～250Keiomega, it is sealing treatment
The present invention relates to a dispersion-type organic photoconductor in which the photosensitive layer is formed on a porous alumite layer .

The photoreceptor of the present invention is sealed with nickel acetate or nickel fluoride, has an impedance of 85 to 250 KΩ, and a porous layer having a thickness of 1 to 1.
A conductive support having an alumite layer having a thickness of 0 μm and a barrier layer of 10 to 1000 °, and an organic charge generation material and an organic charge transport material provided on the conductive support are dispersed in a binder resin. And a photosensitive layer having a thickness of 30 to 60 μm.

In the present invention, by providing an alumite layer, even if the photosensitive layer has a thicker photosensitive layer than the conventional one, the accumulation of charges in the photosensitive layer during repeated use is eased, and the charging ability is reduced. It is possible to prevent a decrease and a rise in the residual potential as much as possible, and to effectively prevent the deterioration of the image, for example, the roughness of the image and the black spots.

First, the alumite layer constituting the photoreceptor of the present invention will be described.

The alumite layer comprises two layers, a barrier layer and a porous layer provided on an aluminum conductive support. The role of the alumite layer is to provide adhesiveness, prevent charge injection, rectify, and the like.

In order for the alumite layer to have charge injection preventing properties, it is necessary to increase the thickness of the barrier layer. However, if the barrier layer is too thick, the residual potential will increase, causing a reduction in sensitivity and fogging that may occur during repetition. Therefore, the thickness of the barrier layer is 10 to 10
00 °, preferably 10-500 °.

The porous layer is required to have a certain thickness in order to provide adhesion, but if it is too thick, it appears as an increase in residual potential and an increase in dark current. Therefore, the thickness of the porous layer is desirably 1 to 10 μm , preferably 2 to 8 μm .

More preferably, the alumite layer of the present invention is partially subjected to a sealing treatment. Partially means that only the surface is sealed with cavities remaining in the porous layer. The degree of sealing can be adjusted by the time for sealing treatment, the concentration of the sealing agent, the temperature of the solution, and the like. N in the alumite layer by partial sealing
Due to impurities such as i, the flow of electrons is performed smoothly,
On the other hand, the holes themselves are prevented from being injected by the barrier property of the alumite layer, so that good rectifying properties can be obtained.

The alumite layer is formed by subjecting an aluminum support, which has been processed into an appropriate shape such as a cylindrical shape, to an anode as a support for the photoreceptor, and performing an electrolytic treatment using sulfuric acid or oxalic acid as an electrolytic solution. To form an alumite layer. The thickness of the barrier layer can be adjusted by adjusting the electrolysis voltage, and the thickness of the porous layer can be adjusted by adjusting the electrolysis time.

The sealing treatment is performed by treating with an aqueous solution such as nickel acetate or nickel fluoride. The concentration of the sealing agent is preferably 1 to 15 wt%, and more preferably 5 to 10 wt%. The temperature of the aqueous solution is preferably 30 to 80C.

The amount of impurities in the alumite layer in the present invention can be adjusted by the material of the aluminum alloy and the conditions of the alumite treatment.

In the alumite layer of the present invention, manganese other than magnesium, iron, copper and silicon, chromium, zinc,
Metals such as titanium may be contained as long as they do not cause charge injection, but the amount is desirably 0.1% by weight or less.

The amount of metal in the alumite layer can be quantified by Auger electron spectroscopy and emission spectroscopy.

Further, the impedance of the alumite layer is 85 to 250 KΩ, preferably 100 to 250 KΩ.
By adjusting to the range described above, it is possible to improve the characteristics of the photoconductor, which are considered to be deteriorated by the alumite treatment, such as an increase in the residual potential and a deterioration in the repetition characteristics.

The impedance can be adjusted by adjusting the electrolysis time and the electrolysis voltage, respectively, or by performing a sealing treatment. If the impedance of the alumite layer is too low, it does not serve as an injection preventing layer, has a low charge retention ability, and generates many white spots during printing. Conversely, if the impedance of the alumite layer is too high, the initial residual potential will increase, causing a decrease in sensitivity, and the residual potential will increase due to repeated copying, resulting in fogging of the image.

The measuring method of the impedance is ASTM-
It can be measured by the standard method according to B457-67. That is, the method is a method of performing measurement using an AC impedance bridge, using a 35% saline solution as an electrolytic solution, measuring at 1000 Hz, repeating the test several times in other places, Take the average.

The impedance of the alumite layer film is proportional to the film thickness, inversely proportional to the measurement area, and affected by the measurement temperature. The impedance of the alumite layer film of the present invention is a value converted into an impedance value under the conditions of a measurement area of 0.129 cm ² and a measurement temperature of 25 ° C.

The charge injection preventing property is greatly affected by impurities in the alumite layer. If iron, copper, silicon, or the like is contained in a large amount as an impurity, prevention of charge injection and rectification are greatly affected. In the present invention, it is particularly preferable to minimize impurities such as silicon, copper, and iron which are considered to cause charge injection. In addition, when magnesium and silicon are contained, a magnesium-silicon alloy that is extremely detrimental is formed. For this reason, it is desirable that the amount of the metal be as small as possible.

As the conductive support in the photoreceptor of the present invention, a cylindrical support is generally used. For example, after being extruded, a drawn aluminum pipe is cut, and the outer surface thereof is cut with a diamond bite. Approximately 0.2-0.3mm cut and finished using a cutting tool such as (cutting tube), or a deep-drawn aluminum disk formed into a cup shape, and the outer surface finished by ironing
(DI tube). Impact-processed aluminum disk made into a cup shape, the outer surface finished by ironing (EI tube), extruded, cold-drawn
(ED tube) or the like is used. Further, these surfaces may be further cut. In addition to the above, the conductive support may be a sheet of aluminum foil or plate, or a sheet obtained by bonding these metals to a plastic film or the like.

The photoreceptor of the present invention has a photosensitive layer formed by dispersing a charge generating material and a charge transporting material in a binder resin after forming an alumite layer on such a conductive support. is there.

In forming the photosensitive layer, the charge generating material and the charge transporting material are dispersed in a solution in which a suitable binder resin is dissolved, and this dispersion is applied on the alumite layer.
Dry to form. The thickness of the photosensitive layer is adjusted to 30 to 60 μm, preferably 35 to 60 μm. Further, the photoreceptor of the present invention may have a surface protective layer, an undercoat layer or an intermediate layer, if necessary.

In the photoreceptor of the present invention, the fine particles of the charge generating material are dispersed in a resin solution or a solution in which the charge transporting material and the resin are dissolved, and the resultant is coated on the outer peripheral surface of the alumite-treated drum and dried. It is produced by this. The application of the photosensitive layer can be performed using various coating apparatuses such as a known one, and specifically, for example, using an applicator, a spray coater, a bar coater, a dip coater, a roll coater, a doctor blade, or the like. Can be. When the compounding ratio of the charge generating material in the photosensitive layer is too small, sufficient sensitivity cannot be obtained, and when it is too large, problems such as poor film formability and low mechanical strength of the photosensitive layer occur. 0.01 to 2 parts by weight, preferably 0.2 to 1.5 parts by weight, based on 1 part by weight of the binder resin therein. When the proportion of the charge transport material is too small, sufficient sensitivity cannot be obtained, and when the proportion is too large, problems such as poor charging and weak mechanical strength of the photosensitive layer occur. 0.01 to 2 parts by weight, preferably 0.03 to 1.3 parts by weight, per 1 part by weight of the resin. The thickness of the photosensitive layer is 30 to 60 μm as described above, preferably 3 to 60 μm.
5 to 60 μm.

In the photoreceptor of the present invention, the mobility of the electric charge in the photosensitive layer is ⁵ × 10 ⁵ V / cm.
By selecting and using a resin and a charge transporting material so as to be 10 to ⁶ cm ² / V · sec or more, it is possible to further improve durability and sensitivity.

Examples of the charge generating material used in the photoreceptor of the present invention include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, cyanine dyes, styryl dyes, and pyrylium dyes. Organic substances such as dyes, azo dyes, chiacdrine dyes, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarylium pigments, and phthalocyanine pigments are exemplified. In addition, any material that absorbs light and generates charge carriers with extremely high efficiency can be used.

The charge transporting material used in the present invention includes, for example, an electron-donating substance composed of a derivative such as hydrazone, triphenylmethane, oxadiazole, carbazole, hydrazone, styryl, imidazole, trinitrofluorenone, tetranitrogen. A substance having a charge transporting property such as an electron donating property such as xanthone, tetracyanoethylene, and tetracyanoquinodimethane can be used.

The binder resin used in the production of the above-mentioned photoreceptor is electrically insulating, and is measured by 1 × 10 ¹²
It is desirable to have a volume resistance of Ω · cm or more. For example, a binder such as a thermoplastic resin, a thermosetting resin, a photocurable resin, or a photoconductive resin known per se can be used. Specifically, saturated polyester resin, polyamide resin, acrylic resin, ethylene-vinyl acetate resin, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, Cellulose ester,
Thermoplastic resins such as polyimide and styrene resin; epoxy resins, urethane resins, silicone resins, phenol resins, melamine resins, xylene resins, alkyd resins, thermosetting resins such as thermosetting acrylic resins; photo-curing resins; polyvinyl carbazole; Examples thereof include photoconductive resins such as polyvinylpyrene, polyvinylanthracene, and polyvinylpyrrole. These binder resins are used alone or in combination of two or more.

When the charge transporting material is a polymeric charge transporting material that can be used as a binder, it is not necessary to use another binder resin.

The photoreceptor of the present invention can be used together with the above binder resin together with a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, O-terphenyl, chloranil, tetracyanoethylene, 2,1,
Electron withdrawing sensitizers such as 7-trinitrofluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-dinitrobenzoic acid, methyl violet, rhodamine B, cyanine dye, pyrylium A sensitizer such as a salt or a thiapyrylium salt may be used.

The solvent for dissolving these resins varies depending on the type of the resin. Examples thereof include aromatic solvents such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone, methyl ethyl ketone and cyclohexanone, methanol, ethanol, and the like. Alcohols such as isopropanol, ethyl acetate, esters such as ethyl cellosolve, carbon tetrachloride, carbon tetrabromide, chloroform, dichloromethane, halogenated hydrocarbons such as tetrachloroethane,
Examples thereof include ethers such as tetrahydrofuran and dioxane, dimethylformamide, dimethylsulfoxide, and diethylformamide.

These solvents may be used alone or as a mixture of two or more.

Further, the photoreceptor of the present invention may have an intermediate layer provided between the alumite layer and the photosensitive layer. As a result, it is possible to improve adhesion, improve coating properties, protect the support, and suppress charge injection from the support side into the photosensitive layer. As the material used for the intermediate layer, polyimide, polyamide, nitrocellulose, polyvinyl butyral, polyvinyl alcohol and the like are suitable, and the film thickness is desirably 1 μm or less. A low-resistance compound may be dispersed in these materials.

Further, the photoreceptor of the present invention may be provided with a surface protective layer. As a material used for the surface protective layer, a polymer such as an acrylic resin, a polyaryl resin, a polycarbonate resin, a urethane resin, a thermosetting resin, a photocurable resin, or a low-resistance substance such as tin oxide or indium oxide may be used. Those dispersed are suitable. The thickness is desirably 5 μm or less.

Further, a protective layer using an organic plasma polymerized film may be used. The organic plasma polymerized film may optionally contain oxygen, nitrogen, halogen, and atoms of groups 3 and 5 of the periodic table.

The photoreceptor of the present invention can be used in various electrophotographic application fields as a photoreceptor for a printer, a facsimile, and the like, in addition to an electrophotographic copying machine, a laser, a light emitting diode (LED), an LCD shutter, a cathode ray tube, etc. as a light source. It can be suitably used.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto unless it exceeds the gist thereof. In the following, “parts” means “parts by weight” unless otherwise specified.

Example 1 An aluminum pipe made of JIS6063 alloy having a mirror-finished surface was etched in a 1% aqueous sodium hydroxide solution at 30 ° C. for 5 minutes, washed with water, and then immersed in 7% sulfuric acid at 25 ° C. for 1 minute. did. After washing with water, in a 150 g / l sulfuric acid electrolyte,
Anodization was performed at a current density of 1.0 A / dm ² to form an anodized film having an average film thickness of 6 μm (barrier layer 300 °). Further, after washing with water, it was immersed in a 10 g / l aqueous solution of nickel acetate at 80 ° C. for 30 minutes, pulled up, and washed with pure water. The impedance of this pipe was 85 KΩ.

On the alumite layer, the following chemical formula:

[0048]

Embedded image

1.5 parts of an azo pigment represented by the following chemical formula:

[0050]

Embedded image

A dispersion coating liquid obtained by dispersing 40 parts of a distyryl compound represented by the following formula and 60 parts of a polycarbonate resin (Panlite K-1300; manufactured by Teijin Chemicals Ltd.) together with 500 parts of 1,4-dioxane for 24 hours in a sand mill for 24 hours. Thickness 3
It was applied to a thickness of 5 μm and dried to form a photosensitive layer. Thus, a dispersion-type and function-separated type photoreceptor was obtained.

Example 2 An aluminum pipe made of JIS 3003 alloy whose surface was cut was etched in a 1% aqueous sodium hydroxide solution at 30 ° C. for 5 minutes, washed with water, and then immersed in 1% nitric acid at 25 ° C. for 1 minute. did. After washing with water, an electrolytic bath containing sulfuric acid 7vol% at 20 ° C. ± 1 ° C., bath voltage 30V, current density 1.2A / dm.
Anodizing is performed in Step ² to obtain an average film thickness of 4 μm (barrier layer 42
An anodized film of 0 °) was formed.

After the obtained aluminum pipe was washed with water, it was immersed in a 7 g / l aqueous solution of nickel fluoride at 70 ° C. for 10 minutes. After immersion, the pipe was pulled up and washed with pure water. The impedance of this pipe was 120 KΩ.

On the alumite layer, 1 part of a τ-type metal-free phthalocyanine, 20 parts of a polycarbonate resin (PC-Z; manufactured by Mitsubishi Gas Chemical Company), the following chemical formula:

[0055]

Embedded image

20 parts of a butadiene compound represented by the formula, 2 parts of a hindered phenol compound (Irganox 565; manufactured by Ciba Geigy), and 0.01 part of fluorosilicone oil (X-22-8-19; manufactured by Shin-Etsu Chemical Co., Ltd.) And 180 parts by weight of tetrahydrofuran (THF) were dispersed by a sand mill for 12 hours, and the dispersion was applied to a dry film thickness of 40 μm, followed by drying to obtain a dispersion-type and function-separated photoconductor.

Example 3 The outer surface of a cylindrical substrate made of aluminum was mirror-polished, washed with dichloromethane, and the liquid temperature was 20 ° C.
A current density of 2.5 A in an electrolyte having a sulfuric acid concentration of 100 g / l
/ Dm ² for 10 minutes to give a film thickness of 7 μm
An anodized film of (barrier layer 800 °) was formed. Further, after washing with water, it was immersed in an aqueous solution of nickel acetate 8 g / l at 90 ° C. for 10 minutes, pulled up, and washed with pure water. The impedance of this pipe was 190 KΩ.

On the alumite layer, 5 parts by weight of a titanyl phthalocyanine pigment, having the following chemical formula:

[0059]

Embedded image

50 parts of a diamino compound represented by the following formula, 50 parts of a polyarylate resin (U-Polymer U-100, manufactured by Unitika), and 10 parts of dibutylhydroxytoluene were dispersed together with 400 parts by weight of dichloroethane using a sand mill for 24 hours. The liquid was applied and dried so as to have a dry film thickness of 45 μm, thereby producing a dispersion-type and function-separated type photoconductor.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that the aluminum base was not anodized.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the thickness of the photosensitive layer was changed to 20 μm.

The obtained photoreceptor was converted to a commercially available electrophotographic copying machine.
(Minolta Camera; EP-5400) +5
Charged by KV corona discharge, the initial surface potential V
₀ (V), the amount of exposure necessary for the surface potential to attenuate to half of the initial surface potential (hereinafter referred to as half-exposure amount) E _1/2 (lux · s
ec), decay rate D of initial potential when left in the dark for 5 seconds
The residual potential Vr (V) after irradiation with DR ₅ (%) and erase light (50 lux · sec) was measured. In addition, the obtained photoreceptor is
After printing for 50,000 continuous copies, 15
After taking 10,000 sheets, the initial surface potential V0, half-exposure amount E1 _{/ 2} ,
The residual potential Vr and the film thickness were measured. Table 1 shows the results.

Further, with respect to each of the photoreceptors of the above Examples and Comparative Examples, white spots in black solid portions, rough spots, white spots in half portions, and image density (ID) of black solid portions in image characteristics were obtained.
Were evaluated based on the following criteria. Table 2 shows the results.

White spots: に お い て In the visual evaluation of the black solid image area, almost no white spots were observed. Very good. △ Some white spots were observed, but no practical problems. × Many white spots were observed. Problematic-Not measured Half: て い る Good reproduction in the gray image part in the non-sighted evaluation △ Some slight white spots but no practical problems × Many white spots were observed and practical problems -With no measurement Gastrox: Good reproduced in visual evaluation of fine line reproducibility △ Some fine line thinning but no problem in practical use × Fine line thinning becomes noticeable and practical problem With-Not measured Black solid image density: ○ ID 1.5 or more △ ID 1.0 to 1.5 × ID less than 1.0-Not measured

[0066]

[Table 1]

[0067]

[Table 2]

[0068]

As described above in detail, according to the photoreceptor of the present invention, the pores are sealed with nickel acetate or nickel fluoride, and the impedance is 85 to 250K.
Ω, the thickness of the porous layer is 1 to 10 μm, and the thickness of the barrier layer is 10 to 1000 °. By providing an alumite layer, the accumulation of charges in the photosensitive layer during repeated use is reduced, and the charging ability is reduced. In addition to preventing a decrease and a rise in the residual potential as much as possible, it has excellent durability and can effectively prevent image deterioration, for example, image roughness and black spots.

[0069]

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 5/00-5/16

Claims (3)

(57) [Claims] 1. A barrier layer having a thickness of 10 to 1000 ° and a thickness.
A conductive support having an alumite layer comprising a porous layer having a thickness of 1 to 10 μm, and a thickness of 30 to 60 μm obtained by dispersing an organic charge generation material and an organic charge transport material in a binder resin.
Of a photosensitive layer, the anodized layer are sealing treatment by nickel acetate or nickel fluoride, sealing
The impedance of the treated anodized layer is 85 to 25
0 KΩ , porous layer of anodized alumite layer
A dispersion-type organic photoconductor, wherein the photosensitive layer is formed thereon. 2. The dispersion type organic photoreceptor according to claim 1, wherein said photosensitive layer has a thickness of 35 to 60 μm. 3. The electric charge mobility in the photosensitive layer is 2 × 10
3. The dispersion type organic photoreceptor according to claim 1, wherein the pressure is 5 × 10 ⁻⁶ cm ² / V · sec or more under a condition of ⁵ V / cm.