JP2857486B2 - Electrophotographic photoreceptor and electrophotographic apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor and an electrophotographic apparatus provided with the photoreceptor, and more particularly, to an extremely high sensitivity containing oxytitanium phthalocyanine in a photosensitive layer. And an electrophotographic apparatus provided with the photoconductor.

[Prior Art] Many electrophotographic photoreceptors using organic materials have been mounted on copiers and optical printers, and the progress of materials has been remarkable.

Of those materials, oxytitanium phthalocyanine (hereinafter abbreviated as TIOPC) has recently attracted attention. TiOPc
Since it has high sensitivity to light with wavelengths around 600 to 800 nm, LE
It is useful as a photoreceptor material for electrophotographic printers or digital copiers using D or a semiconductor laser as a light source.

[Problems to be Solved by the Invention] However, although TiOPc has high sensitivity, it has a drawback that the residual potential is large.

Incidentally, TiOPc is known to take many crystal forms, in particular times in the X-ray diffraction of the Cu K _alpha析角2 [Theta] ± 0.2 ° of 9.0 ° among them, 14.2 °, 23.9 °, a 27.1 ° The crystalline form of TiOPc with a strong peak shows the above characteristics remarkably. That is, although having extremely high sensitivity, the residual potential is high. In such a characteristic, there is a disadvantage that it is difficult to obtain a potential contrast in a system in which the process speed of electrophotography is high or a process cycle is short, and in a system in which a laser spot is small when using laser exposure. . Further, for example, when a laminated photoreceptor is to be formed using TiOPc as a charge generation layer, the formulation design latitude of a charge transport layer, an intermediate layer, a surface protective layer, and the like becomes narrow, which is not preferable.

Accordingly, it is an object of the present invention to improve the above-mentioned drawbacks and to provide an electrophotographic photoreceptor using TiOPc which has a very high sensitivity and a low residual potential, and an electrophotographic apparatus provided with the photoreceptor.

[Means for Solving the Problems] That is, the present invention provides an electrophotographic photosensitive member comprising an organic photoconductive layer on a conductive support, the photoconductive layer (A) Cu K times in the X-ray diffraction of the _α 9.A diffraction angle of 2θ ± 0.2 °
An electrophotographic photoreceptor comprising: a crystalline oxytitanium phthalocyanine having strong peaks at 0 °, 14.2 °, 23.9 ° and 27.1 °; and (B) an azo pigment having a work function Wf ≧ 5.45 eV. And an electrophotographic apparatus provided with the photoconductor.

 Hereinafter, the present invention will be described in detail.

When TiOPc is used in combination with a charge transport material, TiO
Since the work function Wf of Pc is lower than that of a commonly used charge transporting material, carrier injection is not sufficiently performed in a region where the electric field intensity is low, which is considered to be a factor of the residual potential.

The present inventors have paid attention to this point, and after intensive studies, found that the addition of an azo pigment having a higher Wf lowers the residual potential without hindering the original characteristics,
The present invention has been reached. Wf of TiOPc varies depending on its crystal form, but takes a value of about 5.1 to 5.4 eV. In contrast, the effect of the present invention can be obtained when the added azo pigment has a Wf of 5.45 eV or more.

The addition ratio of the azo pigment to TiOPc is suitably 100% by weight to 5% by weight (hereinafter abbreviated as%), and more preferably 70% to 10%.
Is preferred. When the addition ratio of the azo pigment exceeds 100%, TiO
In some cases, the original high-sensitivity characteristics of Pc are significantly impaired.
That is, at 100% or less, the residual potential of the photoconductor can be reduced by the effect of increasing Wf of the entire photoconductive layer without deteriorating the sensitivity. When the addition ratio is lower than 5%, the effect of the present invention is insufficient, which is not preferable.

Further, as inferred from the above description, it is desirable that the azo pigment has a certain degree of light sensitivity. Further, it is preferable to have high sensitivity to the wavelength of the light source of the mounted electrophotographic apparatus (for example, semiconductor laser, LED, etc.).

As such azo pigments, the following general formulas (I) and (I)
Those represented by I) are preferred.

Here, A and A 'are diamine or triamine central skeletons, and B, C and D are compounds having a phenolic hydroxyl group, and may be the same compound.

 Hereinafter, specific examples of A and A 'will be described.

Next, specific examples of B, C, and D will be described.

Next, the general formula of oxytitanium phthalocyanine used as a charge generation material is shown.

Here, X ₁ , X ₂ , X ₃ , and X ₄ represent Cl or Br, and n, m, l, and k are integers of 0 to 4.

References relating to synthesis methods and electrophotographic properties include, for example, JP-A-57-148745, JP-A-59-36254, JP-A-59-44054, JP-A-59-31965, and
1-239248 and 62-67094. The TiOPc obtained according to these is used as a charge generating material.

TiOPc has polymorphism like other phthalocyanines. For example, JP-A-59-49544 (USP 4,444,861),
JP-A-59-166959, JP-A-61-239248 (USP
4,728,592) and JP-A-62-67094 (USP 4,664,99).
7), JP-A-63-366, JP-A-63-116158, JP-A-63-198067 and JP-A-64-17066 report oxytitanium phthalocyanines having different crystal forms. ing.

Among them, (1) crystalline oxytitanium phthalocyanine having strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° at black angle 2θ ± 0.2 ° in X-ray diffraction of CuK _α has high sensitivity. The present invention works effectively.

As the constitution of the photoreceptor of the present invention, both a laminated type of a charge generation layer and a charge transport layer or a single layer type in which a charge generation material and a charge transport material are mixed is applied. In the former case, there are two stacking orders, of which the charge generation layer,
In general, the charge transport layers are stacked in this order. The configuration of the photoconductor will be described using the configuration as an example.

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.

Further, an undercoat layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer.

As a material for the undercoat layer, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, methyl cellulose, casein, polyamide, glue, gelatin, and the like are used.

These are dissolved in a suitable solvent and coated on a conductive support.

Further, it is preferable to provide a conductive layer between the support and the undercoat layer for the purpose of coating unevenness and defects on the substrate and preventing interference fringes due to scattering when image input is performed by laser light. This can be formed by dispersing conductive powder such as carbon black, metal particles, and metal oxide in a binder resin. The thickness of the conductive layer is 5 to 40 microns, preferably
10-30 microns is suitable.

A charge generation layer is provided on the undercoat layer. That is, it is formed by applying and drying a coating material in which a TiOPc and an azo pigment are dispersed in a binder resin dissolved in a solvent.

As the binder resin used here, for example,
Examples mainly include a polyester resin, an acrylic resin, a polyvinyl carbazole resin, a phenoxy resin, a polycarbonate resin, a polyvinyl butyral resin, a polystyrene resin, a polyvinyl acetate resin, a polysulfone resin, a polyarylate resin, and a vinylidene chloride-acrylonitrile copolymer resin.

The ratio (weight ratio: the same applies hereinafter) of the total pigment of TiOPc and the azo pigment to the binder resin is preferably 1/5 to 5/1, and more preferably 1/2 to 3
/ 1 is preferred.

The charge transport layer is formed by coating and drying a coating material in which a charge transport material and a binder resin are dissolved in a solvent.

Examples of the charge transport material used include various triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triallylmethane compounds, and the like. As the binder resin, the same resin as that used for the charge generation layer can be used.

These photosensitive layers can be applied by dipping, spray coating, spinner coating, bead coating, blade coating,
A beam coating method or 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 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 photosensitive member 1 is charged by charging means 2 during its rotation.
Further, the peripheral surface thereof is uniformly charged with a predetermined positive or negative potential, and then, in the exposure section 3, light image exposure L (slit exposure, laser beam scanning exposure, etc.) by an image exposure means (not shown).
Receive. 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 synchronized with the rotation of photoconductor 1 between photoconductor 1 and transfer means 5 from a feeding unit (not shown) by transfer means 5. The transfer material P is sequentially transferred onto the surface of the transferred transfer material P.

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

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 used repeatedly for image formation.

As the uniform charging means 2 for the photoreceptor 1, a corona charging device is generally widely used. The transfer device 5 also generally uses a corona transfer unit. 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, the photoconductor 1 and the cleaning means 6 are integrated into one device unit,
It may be configured to be detachable using a guide means such as a rail of the apparatus body. At this time, the above-described device unit may be provided with a charging unit and / or a developing unit.

When the electrophotographic apparatus is used as a copying machine or a printer, the light image exposure L is a signal reflected from or transmitted from an original, or a signal is read from the original, and the signal is used to scan a laser beam and drive an LED array. Or by driving a liquid crystal shutter array.

When used as a facsimile printer, the light image exposure L is an exposure for printing received data. FIG. 2 is a block diagram showing one example of this case.

The controller 11 controls the image reading unit 10 and the printer 19. The entire controller 11 is controlled by the CPU 17. 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 the printer 19. 14 is a telephone.

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

Note that the CPU 17 is receiving the next page during recording by the printer 19.

 Image reception and recording are performed as described above.

The electrophotographic photoreceptor of the present invention can be widely used not only for electrophotographic copying machines but also for electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

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

Production Example 1 o-phthalodinitrile in 100 g of α-chloronaphthalene
5.0 g and 2.0 g of titanium tetrachloride were heated and stirred at 200 ° C. for 3 hours, and then cooled to 50 ° C., and the precipitated crystals were separated by filtration to obtain a paste of dichlorotitanium phthalocyanine. Next, this was heated to 100 ° C., N, N′-dimethylformamide 100 m
The mixture was washed with 1 l while stirring and then 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 oxytitanium phthalocyanine crystal. Yield 4.
3g. The elemental analysis of this compound was as follows.

Elemental analysis (C ₃₂ H ₁₆ N ₁₈ TiO) Calculated value of CH N Cl (%) 66.68 2.80 19.44 0.00 Actual value (%) 66.50 2.99 19.42 0.47 Next, dissolve the crystals in 30 ml of concentrated sulfuric acid and remove at 20 ° C. The resulting solution was reprecipitated by dropping into 300 ml of deionized water with stirring, filtered, and sufficiently washed with water to obtain amorphous oxytitanium phthalocyanine.

4.0 g of the amorphous oxytitanium phthalocyanine thus obtained was added to 100 ml of methanol at room temperature (22 ° C.).
The mixture was suspended and stirred for 8 hours, filtered, and dried under reduced pressure to obtain oxytitanium phthalocyanine having low crystallinity. Next, 40 ml of n-butyl ether was added to 2.0 g of this oxytitanium phthalocyanine, and milling was performed at room temperature (22 ° C.) for 20 hours together with 1 mmφ glass beads.

The solid was removed from the dispersion, washed thoroughly with methanol and then with water, and dried to obtain the novel oxytitanium phthalocyanine of the present invention. Yield 1.8 g. This oxytitanium phthalocyanine had strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° at Bragg angles 2θ ± 0.2 ° in X-ray diffraction.

[Examples] Next, the present invention will be described in accordance with examples.

Example 1 50 parts of titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of resole type phenol resin,
20 parts of methyl cellosolve, 5 parts of methanol and 0.002 part of silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, average molecular weight 3000) were dispersed in a sand mill using φ1 mm glass beads for 2 hours to prepare a coating for a conductive layer. .

Dip-coat the above paint on an aluminum cylinder (φ30mm × 260mm), dry at 140 ° C for 30 minutes,
m conductive layers were formed.

A solution of 5 parts of a 6-66-610-12 quaternary polyamide copolymer resin in a mixed solvent of 70 parts of methanol and 25 parts of butanol was applied by dipping and dried to form an undercoat layer having a thickness of 1 μm. Provided.

Next, polyvinyl butyral was prepared by dissolving 3 parts of the oxytitanium phthalocyanine crystal (Wf = 5.28 eV) obtained in Production Example 1 of the present invention and 2 parts of a trisazo pigment (Wf = 5.52 eV) having the following structure in 100 parts of cyclohexanone. Two parts of a resin (trade name: Esrec BM-2, manufactured by Sekisui Chemical) were dispersed in a sand mill using 1φ glass beads for 2 hours, and 100 parts of methyl ethyl ketone was added thereto.
After applying this on the undercoat layer, dried at 80 ° C for 10 minutes,
A charge generation layer having a thickness of 0.15 μm was formed.

Next, the following structural formula A solution was prepared by dissolving 10 parts of the charge transporting material represented by the following formula and 10 parts of a bisphenol Z-type polycarbonate resin in 60 parts of monochlorobenzene, and applied to the charge generating layer by dipping. This is dried at 110 ° C for 1 hour and
An m-thick charge transport layer was formed.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that the trisazo pigment was not added.

These Example 1 and Comparative Example 1 were installed in a laser beam printer (trade name: LBP-SX: manufactured by Canon Inc.), and charged so that the dark area potential became -700 (V).
irradiate a laser beam of nm to raise the potential of -700 (V) to -150
The amount of light required for lowering to (V) was measured and defined as sensitivity.
Further, the potential at a light quantity of 5 μJ / cm ² was measured, and this was defined as a residual potential. Table 1 shows the results.

The laser beam spot diameter in this printer is 85 μm in the main scanning direction and 100 μm in the sub scanning direction.
The process speed is 47 mm / sec.

Example 2 A disazo pigment having the following structural formula (Wf = 5.
A photoconductor was prepared in the same manner as in Example 1, except that 76 eV) was used.

Example 3 A disazo pigment having the following structural formula (Wf = 5.
60eV) Except for using the following structure as the charge transport material, A photoconductor was prepared in the same manner as in Example 1.

These photoconductors were evaluated in the same manner as in Example 1. Table 2 shows the results.

Example 4 A photoconductor was prepared in the same manner as in Example 1, except that an aluminum cylinder having a diameter of 80 mm x 360 mm was used.

Comparative Example 2 A photoconductor was prepared in the same manner as in Comparative Example 1, except that an aluminum cylinder having a diameter of 80 mm × 360 mm was used.

These photoconductors were converted to digital color copiers (trade name: CLC
-500, manufactured by Canon) and the dark area potential is -700 (V)
, And irradiating it with a laser beam having a wavelength of 790 nm to measure the amount of light required to reduce the voltage to -700 (V), and the sensitivity was determined. Further, the potential at a light quantity of 5 μJ / cm ² was measured, and this was defined as a residual potential. Table 3 shows the results.

The laser beam spot diameter in this copying machine is 40 μm in the main scanning direction and 60 μm in the sub scanning direction. The process speed is 160 mm / sec.

Example 5 A protective layer was provided on the photoreceptor obtained in Example 1 by the following procedure. 1 part of polytetrachloroethylene powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) was dispersed in a monochlorobenzene solution of 3 parts of a bisphenol Z-type polycarbonate resin, and 2 parts of the charge transport material used in Example 1 was added thereto. In addition, paint was created. This was spray-coated on the photoreceptor to form a 2 μm protective layer.

Comparative Example 3 A protective layer was provided on the photoreceptor obtained in Comparative Example 1 in the same manner as in Example 5.

These photosensitive members were evaluated in the same manner as in Example 1 using a laser beam printer. Table 4 shows the results.

Examples 6 and 7 A photoconductor was prepared by the same way as that of Example 2 except that the addition ratio of the azo pigment to TiOPc was changed as follows.

Example 6 TiOPc 2.5 parts, disazo pigment 2.5 parts Example 7 TiOPc 4.7 parts, disazo pigment 0.3 parts The evaluation results of these photoconductors in the same manner as in Example 1 are shown in Table 5.

[Effects of the Invention] As is clear from the above examples, a photoreceptor obtained by adding an azo pigment having a work function of Wf ≥ 5.45 eV to oxytitanium phthalocyanine has a low residual potential and can fully utilize the characteristics of highly sensitive TiOPc. it can. The effect is more remarkable in a system having a small laser beam spot diameter or a system having a fast process speed. Similarly, the effect sufficiently functions in the case of a photoconductor such as a surface protective layer.

[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. 1: Photoconductor, 2: Charging means 3: Exposure unit, 4: Developing means 5: Transfer means, 6: Cleaning means 7: Pre-exposure means, 8: Image fixing means.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyuki Hanami 3- 30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hideyuki Ainoya 3- 30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-64-17066 (JP, A) JP-A-2-99969 (JP, A) JP-A-1-2577862 (JP, A) JP-A-3-37665 (JP) JP-A-3-37667 (JP, A) JP-A-3-196049 (JP, A) JP-A-2-267563 (JP, A) JP-A-3-250059 (JP, A) (58) Surveyed field (Int.Cl. ⁶ , DB name) G03G 5/06 370 G03G 5/06 340

Claims (5)

(57) [Claims] 1. An electrophotographic photosensitive member having an organic photoconductive layer on a conductive support, wherein the photoconductive layer has a diffraction angle of 2θ ± 0.2 ° in X-ray diffraction of (A) CuKα.
An electrophotographic photoreceptor comprising: crystalline oxytitanium phthalocyanine having strong peaks at 0 °, 14.2 °, 23.9 ° and 27.1 °; and (B) an azo pigment having a work function of Wf ≧ 5.45 eV. 2. The method according to claim 1, wherein the photoconductive layer comprises the component (A) and the component (B).
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor comprises two layers, a charge generation layer containing components and a charge transport layer. 3. The electrophotographic photoreceptor according to claim 2, wherein the charge transport layer is laminated on the charge generation layer containing the components (A) and (B). 4. The electrophotographic photosensitive member according to claim 1, wherein the weight ratio of the component (B) to the component (A) is 5 to 100%. 5. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to any one of claims (1) to (4).