JP2998809B2 - Electrophotographic photoreceptor and electrophotographic apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member which can be widely used in electrophotographic applications such as an electrophotographic copying machine, a laser beam printer, and a plain paper FAX, and an electrophotographic apparatus using the same.

[0002]

2. Description of the Related Art Electrophotography is disclosed in U.S. Pat. No. 2,297,691.
As shown in the publication, a photoconductive material comprising a support coated with an insulating substance is used in which the electric resistance changes according to the amount of irradiation received during image exposure, and in a dark place. The basic characteristics required of an electrophotographic photoreceptor using this photoconductive material are (1) that it can be charged to an appropriate potential in a dark place. (2) There is little charge dissipation in a dark place.
(3) Charges can be quickly dissipated by light irradiation.

[0003] Conventionally, selenium,
Inorganic photoreceptors having a photosensitive layer mainly containing an inorganic photoconductive compound such as zinc oxide and cadmium sulfide have been widely used. However, they satisfy the conditions of (1) to (3), but cannot always satisfy thermal stability, moisture resistance, durability, productivity, and the like. For example, when selenium is crystallized, its characteristics as a photoreceptor are deteriorated, so that it is difficult to manufacture the photoreceptor. In addition, heat, fingerprints, and the like cause crystallization, which degrades the performance as a photoreceptor. In addition, cadmium sulfide has moisture resistance and durability, and zinc oxide has smoothness, hardness,
There is a problem with friction resistance. Furthermore, the photosensitive wavelength region of many inorganic photosensitive members is limited. For example, the photosensitive wavelength region of selenium is the blue region and has little sensitivity in the red region.

For this reason, various methods have been proposed to extend the photosensitivity to the long wavelength region, but there are many restrictions on the selection of the photosensitive wavelength region. Even when zinc oxide or cadmium sulfide is used as a photoreceptor, the photosensitive wavelength range of the photoreceptor itself is narrow, and it is necessary to add various sensitizers.

In order to overcome the disadvantages of these inorganic photoreceptors, electrophotographic photoreceptors containing various organic photoconductive compounds as main components have been actively developed in recent years. For example, U.S. Pat. No. 3,838,851 discloses a photoreceptor having a charge transport layer containing triallylpyrazoline, U.S. Pat.
Japanese Patent No. 871882 discloses a photoreceptor including a charge generation layer composed of a perylene pigment derivative and a charge transport layer composed of a condensate of 3-propylene and formaldehyde.

A photoreceptor using a bisazo pigment or a trisazo pigment as a charge generating substance is disclosed in
No. 3445, JP-A-56-46237, JP-A-60-111249 and the like are known.

Further, the photosensitive wavelength range of the electrophotographic photosensitive member can be freely selected depending on the organic photoconductive compound. For example, azo organic pigments are disclosed in JP-A-61-272754 and JP-A-56-16.
No. 7759 discloses substances exhibiting high sensitivity in the visible region, and substances disclosed in JP-A-57-195767 and JP-A-61-228453 disclose substances in the infrared region. Those having a sensitivity up to this point are also shown.

Among these materials, those having sensitivity in the infrared region are used in laser beam printers (hereinafter abbreviated as LBPs), LED printers, and the like, which have been making remarkable progress in recent years, and the demand frequency is increasing.

Particularly, in recent years, oxytitanium phthalocyanine (hereinafter referred to as TiOc) has been used as a material having high sensitivity in the infrared region.
(Abbreviated as). It is known that TiOPc takes many crystal forms.
No. 6, Japanese Patent Application No. 1-319934, and the like, show crystal forms.

[0010]

However, although an electrophotoreceptor using TiOPc as a charge generating substance is very sensitive and has sensitivity up to the infrared region, it has a problem of black spot image defects and the like. There was a drawback that potential fluctuations easily occurred.

Accordingly, it is an object of the present invention to provide a black-spotted image defect even at a high temperature and a high humidity without impairing the excellent characteristics of an electrophotographic photosensitive member using TiOPc, and with a small potential fluctuation. Electrophotographic photoreceptor and electronic
A photographic device is provided.

[0012]

In accordance with the present invention, in order to solve the problems], an electrophotographic photosensitive member comprising a charge generating layer and a charge transport layer on an electroconductive substrate, said charge generation layer is an average particle diameter of 0.15μm
The following oxytitanium phthalocyanine is contained ,
The transport layer is 2-N, N-di (4-methylphenyl) amido
An electrophotographic photoreceptor characterized by containing no-9,9-dimethylfluorene is provided. In addition, the electrophotography
An electrophotographic apparatus provided with a photoreceptor is provided.
It is.

Hereinafter, the present invention will be described in detail. In the present invention, the average particle size refers to the average particle size in terms of sphere.

The present inventors have found that, in an electrophotographic photoreceptor containing oxytitanium phthalocyanine as a charge generating substance, the presence of a site where the amount of generated carriers is extremely large in the charge generating layer is particularly high temperature and high humidity. The phenomenon that black spot-like image defects occur or the residual potential is higher than the initial level or increases with time occurs only when the average particle size of TiOPc exceeds 0.15 μm. It was found that it did not occur below 15 μm.

This phenomenon occurs because the electrophotographic photosensitive member using TiOPc for the charge generation layer has a very high sensitivity since the amount of carriers generated by TiOPc is large and carriers can be easily injected into the charge transport layer. This is caused by the large amount of carriers generated from the site when the giant particles exist. Regarding this phenomenon, the effect of reducing the average particle diameter of the charge generating substance to a specific value or less is not so large in the conventional relatively low-sensitivity photoreceptor, and the improvement effect is not so large. When a high-sensitivity charge generating substance is used, a remarkable improvement effect can be obtained by setting the average particle diameter to a specific value or less.

The preferred range of the average particle size is 0.07 to 0.1.
15 μm.

Means for reducing the average particle size of TiOPc to 0.15 μm or less include a wet dispersion method. Examples of the wet dispersing device to be used include a sand mill, a ball mill, a paint shaker, and a homomixer. Among these, it is desirable to use a sand mill in terms of dispersion treatment capacity and crushing force for dispersion.

Next, the present invention will be described according to an actual configuration. The conductive support may be any material having conductivity, such as aluminum, a metal such as stainless steel, or a metal provided with a conductive layer, plastic, or paper.
Examples of the shape include a cylindrical shape and a film shape.

When the image input is a laser beam such as LBP, it is preferable to provide a conductive layer for preventing interference fringes due to scattering. This can be formed by dispersing conductive powder such as carbon black and metal particles in a binder resin. The thickness of the conductive layer is 5 to 40 μm, preferably 1
0 to 30 μm.

It is preferable to provide an intermediate layer made of polyamide thereon. The thickness of the intermediate layer is 0.2 to 5 μm, preferably 0.5 to 1 μm.

On the intermediate layer, a coating liquid in which TiOPc is dispersed in a binder resin dissolved in a solvent is applied and dried to form a charge generation layer.

Examples of the binder resin used herein include polyester resin, polyacryl resin, polyvinyl carbazole resin, phenoxy resin, polycarbonate resin, polystyrene resin, polyvinyl acetate resin, polysulfone resin, polyarylate resin, vinylidene chloride-acrylonitrilo copolymer resin And polyvinyl benzal resin are mainly used. The ratio of the binder resin to the pigment is preferably 1/5 to 5/1, and more preferably 1/2 to 3/1.

The charge transport layer is formed by applying and drying a coating material in which a charge transport material and a binder resin are dissolved in a solvent. The charge transport material used is 2-N, N-di-
(4-methylphenyl) amino-9,9-dimethylfur
Oren. As the binder resin, the same resin as that used for the charge generation layer can be used.

As a method for applying these photosensitive layers, a dipping method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method and the like can be used.

FIG. 1 shows a schematic configuration example of a general transfer type electrophotographic apparatus using the electrophotographic photosensitive member of the present invention.

In FIG. 1, reference numeral 1 denotes a drum type photosensitive member of the present invention as an image carrier, which is driven to rotate around an axis 1a in a direction indicated by an arrow at a predetermined peripheral speed. The photoreceptor 1 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by a charging means 2 during the rotation process, and then, in an exposure section 3, a light image exposure L (slit exposure / Laser beam scanning exposure). As a result, an electrostatic latent image corresponding to the exposure image is sequentially formed on the peripheral surface of the photoconductor.

The electrostatic latent image is then developed with toner by developing means 4, and the developed toner image is transferred by a transfer means 5 between a photosensitive member 1 and a transfer means 5 from a paper feeding unit (not shown). The transfer material P is sequentially transferred onto the surface of the transfer material P which is synchronously taken out and fed.

The transfer material P which has undergone the image transfer is separated from the photoreceptor surface, introduced into the image fixing means 8 and subjected to image fixing to be printed out as a copy (copy) outside the machine.

The surface of the photoreceptor 1 after the image is transferred is cleaned by a cleaning unit 6 to remove the untransferred toner, and is further subjected to a static elimination process by a pre-exposure unit 7 to be used repeatedly for image formation.

As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used. Transfer device 5
Also, corona transfer means are generally widely used. As an electrophotographic apparatus, a plurality of components such as the above-described photoreceptor, developing means, and cleaning means are integrally connected as an apparatus unit, and this unit is configured to be detachable from the apparatus body. May be. For example, photoconductor 1
The cleaning unit 6 and the cleaning unit 6 may be integrated into one device unit, and may be configured to be detachable using a guide unit such as a rail of the device body. At this time, the above-described device unit may be provided with a charging unit and / or a developing unit.

When used as an electrophotographic apparatus, a copying machine or a printer, the light image exposure L is a signal reflected from or transmitted from an original, or a read signal from the original. , Or by driving a liquid crystal shutter array. When used as a facsimile printer, the light image exposure L is exposure for printing received data.
FIG. 2 is a block diagram showing an example of this case.

The controller 11 controls the image reading unit 10 and the printer 19. The whole controller 11 is CP
It is controlled by U17. The read data from the image reading unit 10 is transmitted to the partner station through the transmission circuit 13. Data received from the partner station is sent to the printer 19 through the receiving circuit 12. The image memory 16 stores predetermined image data. The printer controller 18 controls a printer 19. 14 is a telephone.

The image information received from the line 15 (image information from a remote terminal connected via the line) is demodulated by the receiving circuit 12 and then decoded by the CPU 17. Is stored. When the image information of at least one page is stored in the memory 16, the image of the page is recorded. The CPU 17 reads one page of image information from the memory 16 and sends the decoded one page of image information to the printer controller 18. Upon receiving the image information of one page from the CPU 17, the printer controller 18 controls the printer 19 to record the image information of the page.

The CPU 17 receives the next page during recording by the printer 19.

As described above, image reception and recording are performed.

The electrophotographic photosensitive member of the present invention can be used not only for an electrophotographic copying machine but also for a laser beam printer,
RT printer, LED printer, LCD printer,
It can be widely used in electrophotographic applications such as laser plate making.

Next, a production example of TiOPc used in the present invention will be described.

[Production Example 1] α-chloronaphthalene 100
g, 5.0 g of o-phthalodinitrile and 2.0 g of titanium tetrachloride were heated and stirred at 200 ° C for 3 hours, and then heated to 50 ° C.
After cooling to room temperature, the precipitated crystals were separated by filtration to obtain a paste of dichlorotitanium phthalocyanine. Next, put this at 100 ° C
N, N'-dimethylformamide heated to 100ml
The mixture was stirred and washed with, and washed twice with 100 ml of methanol at 60 ° C, followed by filtration. Further, the obtained paste was stirred in 100 ml of deionized water at 80 ° C. for 1 hour and filtered to obtain blue TiOPc crystals. Yield 4.3 g.

The elemental analysis of this compound was as follows. Elemental analysis (C ₃₂ H ₁₆ N ₈ TiO) CH N Cl Calculated (%) 66.68 2.80 19.44 0.00 Found (%) 66.50 2.99 19.42 0.47 Next, the crystals were dissolved in 30 ml of concentrated sulfuric acid, dropped into 300 ml of deionized water at 20 ° C. with stirring to reprecipitate, filtered and sufficiently washed with water to obtain amorphous TiOPc. 4.0 g of this amorphous TiOPc was suspended and stirred in 100 ml of methanol at room temperature (22 ° C.) for 8 hours, filtered and dried under reduced pressure to obtain low-crystalline TiOPc. Furthermore, low crystallinity T
To 2.0 g of iOPc, 40 ml of n-butyl ether was added, and milling was performed together with 1 mmφ glass beads at room temperature (22 mm).
C) for 20 hours. Solids were taken out of the dispersion, washed thoroughly with methanol and water, and dried. Yield 1.8
g.

[0040] 9.0 ° of the diffraction angle 2 [Theta] ± 0.2 ° in the crystal CuKα characteristic X-ray diffraction, 14.2 °, 23.
It had strong peaks at 9 ° and 27.1 °.

[Production Example 2] In accordance with a production example disclosed in Japanese Patent Application Laid-Open No. 61-239248 (US Pat. No. 4,728,592), a so-called α-type crystal T
iOPc was obtained.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of embodiments.

(Example 1) Based on an A1 cylinder having a diameter of 30 mm and 260 mm, a coating composed of the following materials was applied on a substrate by a dipping method, and was thermally cured at 140 ° C. for 30 minutes to obtain an 18 μm conductive material. A layer was formed. Conductive pigment: Tin oxide-coated titanium oxide 10 parts (parts by weight, the same applies hereinafter) Resistance adjusting pigment: titanium oxide 10 parts Binder resin: phenol resin 10 parts Leveling agent: silicone oil 0.001 part Solvent: Methanol / methyl cellosolve = 1/1... 20 parts Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymerized nylon in 65 parts of methanol and 30 parts of n-butanol was applied thereto. 1.0μ
m of intermediate layers were formed.

Next, 3 parts by weight of the pigment prepared in Production Example 1, 2 parts of polyvinyl butyral (trade name: Slek BM-2, manufactured by Sekisui Chemical) and 80 parts of cyclohexanone were dispersed in a sand mill using φ1 mm glass beads for 4 hours. And 115 parts of methyl ethyl ketone were added to obtain an average particle size of 0.1.
A charge generation layer dispersion containing 15 μm of TiOPc was obtained.
This was applied on the intermediate layer by a dipping method to form a 0.2 μm charge generation layer. The charge generation layer of the produced electrophotographic photosensitive member was peeled off to obtain a powder, the powder was ultrasonically dispersed, and the average particle diameter of TiOPc was measured with a laser particle size meter. It has been confirmed that the average particle size is the same as the average particle size in the dispersion for use.

10 parts of a bisphenol Z polycarbonate resin (viscosity average molecular weight 22,000) and 10 parts of a charge transport material represented by the following structure

[0046]

Embedded image It was dissolved in 50 parts of monochlorobenzene and 10 parts of dichloromethane. This paint was applied on the above-mentioned charge generating layer by a dipping method, and dried at 110 ° C. for 1 hour to form a 20 μm charge transport layer.

The image of the obtained photoreceptor was evaluated. For evaluation, LBP (trade name “Laser Shot”) manufactured by Canon was used. The environment was 35 ° C. and 85% RH. In the evaluation of black spots, the number of black spots in the image area of 5 × 5 cm ² was ranked as shown in Table 1.

After an image was formed at 35 ° C. and 85% RH, the residual potential was measured under the same environment. After the measurement of the residual potential, a continuous image output durability test was performed on 2,000 sheets, and the potential immediately after that was measured to determine how much the residual potential had increased. Table 2 shows the results.

Example 2 Sample No. In the preparation of the dispersion for charge generation layer 1, the dispersion time was set to be longer than 4 hours, and a sample having an average particle diameter shown below was prepared. No. No. 234556 Average particle size (μm) 0.14 0.13 0.12 0.11 0.10 7 Average particle size (μm) 0.09 Example 1 except that the average particle size of the dispersion for charge generation layer was changed.
A photoreceptor was prepared in the same manner as described above. The same evaluation as in Example 1 was performed using the obtained photoreceptor, and the results are shown in Table 2.

(Comparative Example 1) In the preparation of the dispersion for charge generation layer 1, the dispersion time was changed to less than 4 hours to prepare a sample having the following average particle diameter. No. 8 9 10 11 12 Average particle size (μm) 0.16 0.17 0.18 0.20 0.25 Example 1 except that the average particle size of the dispersion for the charge generation layer was changed.
A photoreceptor was prepared in the same manner as described above. The same evaluation as in Example 1 was performed using the obtained photoreceptor, and the results are shown in Table 2.

[0051]

[Table 1]

[0052]

[Table 2] As described in the above examples, the average particle size of the coating liquid using TiOPc as the charge generating substance is 0.15 μm.
By using the following, it is possible to produce an electrophotographic photoreceptor having high sensitivity, no image defects even under high temperature and high humidity, and little change in potential even under high temperature and high humidity. Also,
TiOPc has diffraction angle 2θ in CuKα characteristic X-ray diffraction
± 0.2 ° in 9.0 °, 14.2 °, 23.9 ° , 2
The effect is particularly remarkable when there is a strong peak at 7.1 °.

As shown in the comparative example, the average particle size was 0.15.
When it is larger than μm, no improvement effect on the image characteristics and potential fluctuation is recognized as compared with the case where it is smaller.

[0054]

The electrophotographic photoreceptor of the present invention suppresses image defects, especially black spots under high temperature and high humidity, without impairing excellent electrophotographic characteristics, and reduces potential fluctuations under the same environment. This makes it possible to obtain a stable image in all environments.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a general transfer type electrophotographic apparatus.

FIG. 2 is a block diagram of a facsimile using the electrophotographic apparatus as a printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging means 3 Exposure part 4 Developing means 5 Transfer means 6 Cleaning means 7 Pre-exposure means 8 Image fixing means

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Kishi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Aoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Hideki Anayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-95964 (JP, A) JP-A-4-198367 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 5/06

Claims (3)

(57) [Claims] A charge generation layer and a charge transport layer on a conductive support.
An electrophotographic photosensitive member comprising a Okuso, said charge generating layer contains the following oxytitanium phthalocyanine average particle diameter 0.15 [mu] m, the charge transport layer is 2-N, N-di (4-
Methylphenyl) amino-9,9-dimethylfluorene
An electrophotographic photosensitive member, characterized in that it contains a. 2. The oxytitanium phthalocyanine has a diffraction angle 2θ ± 0.2 in CuKα characteristic X-ray diffraction.
° of 9.0 °, 14.2 °, 23.9 ° and 27.1 °
2. The electrophotographic photosensitive member according to claim 1, which has a strong peak. 3. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1 or 2 wherein.