JP2002296813A - Electrophotographic photoreceptor, electrophotographic apparatus with the same, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable electrophotographic photoreceptor less liable to a potential change in continuous use in any environment, a process cartridge with the electrophotographic photoreceptor and an electrophotographic apparatus. SOLUTION: In the electrophotographic photoreceptor having a photosensitive layer on an electrically conductive substrate, the photosensitive layer is a laminate of an electric charge transporting layer and an electric charge generating layer, a dispersive solvent for a coating material for manufacturing the electric charge generating layer is a mixed solvent of an organic solvent and water having >=1 mass% water content and the electric charge generating layer is formed using a dispersion prepared by mixing oxy-titanium phthalocyanine and the mixed solvent by liquid collision under high pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to an electrophotographic photosensitive member having high sensitivity and excellent potential stability, a process cartridge using the photosensitive member, and an electrophotographic apparatus.

[0002]

2. Description of the Prior Art Electrophotography is disclosed in U.S. Pat. No. 2,297,6.
As shown in JP-A-91, the electrical resistance changes according to the amount of irradiation received during image exposure, and in a dark place, a photoconductive material composed of a support coated with an insulating substance is used. The basic characteristics required of an electrophotographic photoreceptor using this photoconductive material include (1) being able to be charged to an appropriate potential in a dark place, (2) having little charge dissipation in a dark place, (3) The charge can be quickly dissipated by light irradiation.

Conventionally, as an electrophotographic photoreceptor, an inorganic photoreceptor having a photosensitive layer mainly composed of an inorganic photoconductive compound such as selenium, zinc oxide and cadmium sulfide has been widely used. However, they satisfy the above conditions (1) to (3), but do not 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. In addition, heat, fingerprints, and the like cause crystallization, and the performance as a photoreceptor is degraded. Cadmium sulfide has problems in moisture resistance and durability, and zinc oxide has problems in smoothness, hardness and 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. 3,837,851 discloses a photoreceptor having a charge transport layer containing triallyl pyrazoline, and U.S. Pat. No. 3,871,882 discloses a photoreceptor having a charge generation layer comprising a derivative of perylene pigment. A photoreceptor comprising a charge transport layer comprising a condensate of propylene and formaldehyde;

A photoreceptor using a bisazo pigment or a trisazo pigment as a charge generating substance is disclosed in JP-A-59-33.
No. 445, JP-A-56-46237, JP-A-60-111249, and the like.

Further, the photosensitive wavelength range of the electrophotographic photosensitive member can be freely selected depending on the organic photoconductive compound. For example, with respect to azo-based organic pigments, JP-A-61-272754 and JP-A-56-272754 disclose the same.
As the substance disclosed in Japanese Patent No. 167759, a substance exhibiting high sensitivity in a visible region is disclosed.
The substances disclosed in JP-A No. 67 and JP-A-61-228453 have sensitivity up to the infrared region.

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

Particularly, in recent years, oxytitanium phthalocyanine (hereinafter referred to as TiOP) has been used as a material having high sensitivity in the infrared region.
Abbreviated as c. ) Is drawing attention. It is known that TiOPc takes many crystal forms.
JP-A-366 and JP-A-3-128973 disclose crystal forms.

However, an electrophotographic photoreceptor using TiOPc as a charge generating substance has a very high sensitivity and a sensitivity up to the infrared region, but has a large potential during continuous durability under an environment. Sometimes fluctuated.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a conventional Ti
An object of the present invention is to provide an electrophotographic photosensitive member that does not easily cause potential fluctuation during continuous durability in an environment without impairing the excellent characteristics of the electrophotographic photosensitive member using OPc.

[0012]

According to the present invention, there is provided an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer is a laminate of a charge transport layer and a charge generating layer. The dispersing solvent for paints for producing has a water content of 1% by mass or more, and is a mixed solvent of an organic solvent and water,
The charge generation layer is an electrophotographic photoreceptor characterized in that it is a layer formed using a dispersion in which oxytitanium phthalocyanine and the mixed solvent are mixed by liquid collision under high pressure conditions.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

As a result of repeated studies to improve the above-mentioned disadvantages, the present inventors have found that a mixed solvent of an organic solvent and water is used as a dispersing solvent for a paint for producing the charge generation layer. In addition, the charge generating substance is pressurized to a high pressure state together with the mixed solvent and dispersed by the liquid collision under the high pressure condition, so that the generation of ionic impurities in the charge generation layer is small and the affinity for water is low. It has been found that efficient dispersion can be achieved even with a bad organic solvent, and that the liquid stability of the paint can be improved, thereby eliminating the drawback that the potential fluctuates greatly during continuous durability in an environment. Was.

In the present invention, the water content of the dispersing solvent for paint for preparing the charge generating layer is 1% by mass or more, preferably 1% by mass or more and 5% by mass or less.

As a result, it is possible to obtain an electrophotographic photosensitive member having a high sensitivity and a small potential fluctuation due to continuous durability under an environment.

Next, the present invention will be described according to an actual configuration.

The conductive support may be any conductive material, and examples thereof include metals such as aluminum and stainless steel, and metals, plastics, and papers provided with a conductive layer. And the like.

When an image input such as LBP is a laser beam, it is preferable to provide a conductive layer for preventing interference fringes due to scattering. This layer 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 preferably 5 to 40 μm,
More preferably, it is 10 to 30 μm.

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

On the intermediate layer, TiOP is used as a charge generating material.
A coating liquid in which c is dispersed in an appropriate binder resin is applied and dried to form a charge generation layer.

TiOPc that can be used in the present invention includes a Bragg angle 2θ ± in X-ray diffraction of CuKα.
9.0%, 14.2%, 23.9% and 2 of 0.2%
A crystalline form of TiOPc having a strong peak at 7.1 ° is preferred.

Examples of the binder resin 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, Examples include, but are not limited to, polyvinyl benzal resins. These may be used alone, as a mixture, or as one or more kinds of copolymer polymers. The mass ratio of the binder resin to the charge generating substance is preferably 1/5 to 5/1, and more preferably 1/2 to 3/1.

The solvent for dispersing the charge generating substance may be a mixed solvent of an organic solvent and water.
Examples include, but are not limited to, tetrahydrofuran, cyclohexanone, methyl ethyl ketone, ethyl acetate, methanol, methyl cellosolve, acetone, dioxane, and the like. In particular, the water content of the solvent is preferably 1% by weight or more. Particularly preferably, the water content is 1 wt% or more and 5 wt% or less.

The thickness of the charge generation layer is preferably 5 μm or less, particularly preferably 0.01 to 2 μm.

Further, various additives such as a sensitizer and a deterioration inhibitor may be added to the charge generation layer.

As a dispersing means, a general-purpose sand mill, roll mill, ball mill, attritor, homogenizer and the like can be used, but it is particularly preferable to use a high-pressure liquid collision dispersing apparatus.

The high-pressure liquid collision dispersion apparatus according to the present invention comprises:
A device for pumping a fluid into a fine flow path and pulverizing and dispersing a dispersion by high-pressure liquid collision in the fine flow path. It is composed of a jig and a jig processed so that the liquids collide when the liquid is discharged from the orifice. The high pressure referred to in the present invention is generally determined from the discharge amount, discharge pressure and orifice system and length of the high-pressure pump, and further from the viscosity of the dispersion, and is expressed as a load per unit area of 4.9 to 137 MPa. (50-140
0 kg / cm ² ).

FIG. 3 is a schematic structural view of an example of an apparatus for causing liquid collision at a high pressure used in the present invention. Briefly describing the apparatus with reference to FIG. 3, the dispersion introduced from the dispersion introduction container 31 is filled in the pipe 33 during the suction-discharge process of the high-pressure pump 32. As the high-pressure pump 32, a pump using a hydraulic cylinder, a plunger pump, or the like is used. The dispersion is supplied to the liquid collision jig 34 during the compression process of the pump.
And several orifices 37 (50 μm in diameter)
(2 mm, length 2 to 10 mm), a liquid collision in a high pressure state is performed. Sample receiving container 35
Can be returned to the dispersion container 31 as necessary, and the process can be repeated until desired physical properties are obtained. Further, it is also possible to control the temperature of the liquid in the pipe by the heat exchange system. In addition, 3 in the figure
3 is a pipe, 36 is a pressure gauge, and 38 is a three-way valve.

The charge transport layer is formed mainly by dissolving a charge transport substance and a binder resin in a solvent and applying and drying a paint obtained. Examples of the charge transport material used include various triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds. 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 the figure, reference numeral 1 denotes a drum-type photoconductor of the present invention as an image carrier, which is driven to rotate around an axis 1a in a direction of an arrow at a predetermined peripheral speed. The photoreceptor 1 receives a uniform charge of a predetermined positive or negative potential on its peripheral surface by a charging means 2 during the rotation process,
Next, the exposure unit 3 receives light image exposure L (slit exposure, laser beam scanning exposure, etc.) by an image exposure unit (not shown). As a result, an electrostatic latent image corresponding to the exposure image is sequentially formed on the peripheral surface of the photoconductor 1.

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 from a paper feeding unit (not shown) between the photosensitive body 1 and the transfer means 5. Are sequentially transferred onto the surface of the transfer material P which is taken out and fed in synchronization with the rotation of. The transfer material P having undergone the image transfer is separated from the surface of the photoreceptor 1 and introduced into the image fixing means 8 where the image is fixed and printed out of the machine as a copy. The surface of the photoreceptor 1 after the image transfer is cleaned and cleaned by removing the untransferred toner by the cleaning means 6, and further subjected to a charge removal treatment by the pre-exposure means 7 to be repeatedly used for image formation.

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

In the case where the electrophotographic apparatus is used as a copying machine or a printer, the light image exposure L is performed by reflecting or transmitting light from the original or by reading the original and converting it into a signal. , Or by driving a liquid crystal shutter array.

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.

[0037]

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

Production Example 1 5.0 g of o-phthalodinitrile and 2.0 g of titanium tetrachloride in 100 g of α-chloronaphthalene were heated and stirred at 200 ° C. for 3 hours, and then cooled to 50 ° C. The precipitated crystals were separated by filtration to obtain a paste of dichlorotitanium phthalocyanine. Next, this was washed by stirring with 100 ml of N, N'-dimethylformamide heated to 100 ° C.
The washing was repeated twice with 100 ml of methanol, followed by filtration.
Further, the obtained paste is mixed with 100 ml of deionized water in 8 ml.
The mixture was stirred at 0 ° 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 value (C ₃₂ H ₁₆ N ₈ TiO) CH N Cl Calculated value (%) 66.68 2.80 19.44 0.00 Actual value (%) 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, reprecipitated, 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 a milling treatment was performed together with 1 mmφ glass beads at room temperature (22 ° C.) for 20 hours. The solid content was taken out of the dispersion, washed thoroughly with methanol and water, and dried. Yield 1.8 g.

Diffraction angle 2θ ± in X-ray diffraction of this crystal
9.0%, 14.2%, 23.9%, 27% of 0.2%.
It had a strong peak at 1 °.

The following is a description of the embodiment.

Example 1 A 30φ × 260mm Al cylinder was used as a conductive support, and a coating composed of the following materials was applied on the support by a dipping method, and thermally cured at 140 ° C. for 30 minutes. 1
An 8 μm conductive layer was formed.

Conductive pigment: tin oxide-coated titanium oxide 10 parts 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 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 thereon by a dipping method to form a 1.0 μm
m of intermediate layers were formed.

Next, 3 parts of the pigment prepared in Production Example 1, 2 parts of polyvinyl butyral (trade name: Eslec BM-2, manufactured by Sekisui Chemical) and 80 parts of a mixed solvent of cyclohexanone: water = 98: 2 are shown in FIG. Dispersion treatment was performed with a high-pressure liquid collision dispersion device. The pressure during dispersion is 58.8 MPa (600 kPa).
g / cm ² ). After the liquid obtained from the discharge port was added again and subjected to high-pressure treatment a total of 10 times, 115 parts of ethyl acetate was added to obtain a dispersion for a charge generation layer. This was applied on the intermediate layer by a dipping method to form a 0.2 μm charge generation layer.

The polyvinyl butyral used was treated by the following method. 1 part of butyral was dissolved in 10 parts of dichloromethane for a reagent, filtered through 5C filter paper, and then added dropwise to 100 parts of methanol. After decanting, 60 parts of methanol was added and washed with stirring. The steps after decanting were repeated three times. Thereafter, the mixture was filtered to collect butyral, and dried under reduced pressure.

Next, 10 parts of an amine compound having the following structural formula

[0048]

Embedded image 10 parts of bisphenol Z polycarbonate resin (viscosity average molecular weight 22,000), 50 parts of monochlorobenzene,
Dissolved in 10 parts of dichloromethane. This paint was applied on the above-mentioned charge generation layer by a dipping method, and dried at 110 ° C. for 1 hour to form a charge transport layer of 20 μm.

Example 2 Example 1 was the same as Example 1 except that the number of high pressure treatments was changed to 5.
A photoreceptor was prepared in the same manner as described above.

Example 3 A photoconductor was prepared by the same way as that of Example 1 except that the ratio of the mixed solvent was 97: 3.

Example 4 A photoconductor was prepared by the same way as that of Example 2 except that the ratio of the mixed solvent in Example 2 was changed to 97: 3.

Example 5 The pressure during dispersion in Example 1 was 49.0 MPa (500 kg).
/ Cm ² ), and a photoconductor was prepared in the same manner as in Example 1.

Example 6 The pressure at the time of dispersion in Example 2 was 49.0 MPa (500 kg).
/ Cm ² ), and a photoconductor was prepared in the same manner as in Example 2.

Example 7 The pressure during dispersion in Example 3 was 49.0 MPa (500 kg).
/ Cm ² ), and a photoconductor was prepared in the same manner as in Example 3.

Example 8 The dispersion pressure of Example 4 was set to 49.0 MPa (500 kg).
/ Cm ² ), and a photoconductor was prepared in the same manner as in Example 4.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1, except that a conventional sand mill containing glass beads was used instead of the dispersion treatment using the high-pressure liquid collision dispersion apparatus of Example 1. The processing time of the sand mill was 4 hours.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that the ratio of the mixed solvent in Example 1 was changed to 99.5: 0.5.

Comparative Example 3 A photoconductor was prepared by the same way as that of Example 1 except that the mixed solvent of Example 1 was changed to 100% of cyclohexanone.

Image evaluation was performed on these photosensitive members. For evaluation, LBP manufactured by Canon was used. Environment is 15
° C and 10% RH. In the evaluation of the photoreceptor, the dark portion potential was set to -700 V and the light portion potential was set to -200 V, and the fluctuation amounts ΔVd and ΔVl of the dark portion potential and the light portion potential after continuous running of 3,000 sheets were measured. A positive sign of the variation indicates an increase in the absolute value of the potential, and a negative sign indicates a decrease in the absolute value of the potential.

The results are shown in Table 1.

[0061]

[Table 1] As described in the above examples, TiOPc is used as a charge generating material, and a mixed solvent of an organic solvent and water is used as a coating dispersion solvent for forming a charge generating layer. Is increased to a high pressure state, and dispersed by liquid collision under the high pressure condition, so that the generation of ionic impurities in the charge generation layer is small, and efficient dispersion is possible even with an organic solvent having poor affinity for water. This makes it possible to improve the liquid stability of the coating material, thereby making it possible to produce an electrophotographic photoreceptor having high sensitivity and low potential fluctuation during continuous durability in an environment.

Particularly, TiOPc has a diffraction angle of 29.0 ± 0.2 ° in the X-ray diffraction spectrum of 69.0 °, 14.2 °,
The effect is particularly remarkable in the case of crystals having strong peaks at 23.9 ° and 27.1 °.

Further, in the present invention, as shown in Comparative Example 1, further effects can be obtained as compared with the case where the dispersion treatment is performed by a general-purpose sand mill. Further, the water content of the mixed solvent is 1
When the amount is less than mass%, the potential fluctuates greatly during continuous durability in an environment, so that no significant effect is obtained.

[0064]

According to the present invention, it is possible to obtain a stable electrophotographic photoreceptor having little potential fluctuation during continuous durability under an environment, which is a disadvantage, without impairing excellent electrophotographic characteristics. Further, the same effects can be obtained in a process cartridge and an electrophotographic apparatus in which the electrophotographic photosensitive member of the present invention is combined.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram of an example of an apparatus for causing liquid collision at a high pressure used in the present invention.

[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 31 Dispersion charging container 32 High pressure pump 33 Piping 34 Liquid collision jig 35 Sample receiving container 36 Pressure gauge 37 Orifice 38 Three-way valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H068 AA19 AA21 AA34 AA35 BA39 EA13 EA14 EA36 FA12 FA27

Claims (5)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer is a laminate of a charge transport layer and a charge generation layer, and a coating dispersion for preparing the charge generation layer. The solvent has a water content of 1% by mass or more, and is a mixed solvent of an organic solvent and water. The charge generation layer is a dispersion in which oxytitanium phthalocyanine and the mixed solvent are mixed by liquid collision under high pressure conditions. An electrophotographic photoreceptor, which is a layer formed by using an electrophotographic photoreceptor. 2. The water content is 1% by mass or more and 5% by mass.
2. The electrophotographic photoreceptor according to claim 1, wherein: 3. The oxytitanium phthalocyanine has a Bragg angle of 2 ± 0.5 in X-ray diffraction of CuKα.
9.0%, 14.2%, 23.9% and 27.1 of 2%
3. The electrophotographic photoreceptor according to claim 1, which has a strong peak at ゜. 4. An electrophotographic photosensitive member according to claim 1, and charging means for charging said electrophotographic photosensitive member.
At least one member selected from the group consisting of developing means for developing the electrophotographic photosensitive member on which the electrostatic latent image is formed with toner and cleaning means for collecting residual toner on the electrophotographic photosensitive member after the transfer step A process cartridge integrally supporting the means and being detachable from the electrophotographic apparatus main body. 5. An electrophotographic photosensitive member according to claim 1, a charging means for charging said electrophotographic photosensitive member, and exposing said charged electrophotographic photosensitive member to form an electrostatic latent image. 1. An electrophotographic apparatus comprising: an exposure unit for developing an electrophotographic photosensitive member on which an electrostatic latent image is formed with toner; and a transfer unit for heating and transferring a toner image on a transfer material.