JPH02267563A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the stability of a potential at all times by using an oxytitanium phthalocyanine crystal having strong peaks at plural Bragg angles in the X-ray diffraction spectra of CuKa to constitute a charge generating material on a conductive base. CONSTITUTION:The charge generating material of the electrophotographic sensitive body contg. the charge generating material and charge transfer material on the conductive base is the oxytitanium phthalocyanine crystal in which the Bragg angle 2theta+ or -2 deg. in the X-ray diffraction spectra of the CuKa has the strong peaks at the following values and which is expressed by formula. The Bragg angle attains the values 7.4 deg., 9.2 deg., 10.4 deg., 11.6 deg., 13.0 deg., 14.3 deg., 15.0 deg., 15.5 deg., 23.4 deg., 24.1 deg., 26.2 deg. and 27.2 deg.. X1, X2, X3, X4 denote Cl or Br and n, m, l, k denote 0 to 4 integer. The stability of the potential is extremely good and the good images are maintained in the case of using the photosensitive body repetitively over a long period of time.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing oxytitanium phthalocyanine having a specific crystal form in the photosensitive layer as a charge generating material. Regarding.

[Conventional technology]

In recent years, non-impact printers that apply electrophotographic technology have become widely used as terminal printers, replacing conventional impact printers. These are laser beam printers that mainly use laser light as a light source, and a semiconductor laser is used as the light source from the viewpoint of cost, size of the device, etc.

Semiconductor lasers that are currently mainly used have a long oscillation wavelength of 790±20 nm, and efforts have been made to develop electrophotographic photoreceptors that have sufficient sensitivity to light at these long wavelengths.

Sensitivity on the long wavelength side varies depending on the type of charge-generating material, and many charge-generating materials are being considered.

Typical charge generating materials include phthalocyanine pigments, azo pigments, cyanine dyes, azulene dyes, and squarylium dyes.

On the other hand, metal phthalocyanines or metal-free phthalocyanines such as aluminium lophthalocyanine, lyroloindium phthalocyanine, oxyvanadyl phthalocyanine, chlorogallium phthalocyanine, magnesium phthalocyanine, and oxytitanium phthalocyanine are used as charge-generating materials that are sensitive to long wavelength light. A lot of research has been done.

Among these, many phthalocyanine compounds are known to have polymorphisms; for example, metal-free phthalocyanine has an α-type,
There are β-type, γ-type, δ-type, ε-type,
The types are generally known.

It is also generally known that the crystal type has a great influence on electrophotographic properties (sensitivity, potential stability during durability, etc.) and coating properties when made into a coating.

Furthermore, as mentioned above, oxytitanium phthalocyanine, which has high sensitivity to light with a particularly long wavelength, has polymorphisms as well as other phthalocyanines such as metal-free phthalocyanine and copper phthalocyanine. For example, JP-A-59-
No. 49544 (USP 4.444,861), JP-A-59-166959, JP-A-61-23924
Publication No. 8 (USP 4,728,592), JP-A-62-
67094 (USP 4,664,997), JP-A-63-366, JP-A-63-116158, JP-A-63-198067, and JP-A-64
No. 17066 reports oxytitanium phthalocyanine having different crystal forms.

[Problem that the invention seeks to solve]

The main object of the present invention is to provide succititanium phthalocyanine in a crystal form different from these conventionally reported crystal forms.

Another object of the present invention is to provide an electrophotographic photoreceptor that has extremely high photosensitivity to long wavelength light.

In addition, the purpose of the present invention is that when repeated durability is carried out,
The object of the present invention is to provide an electrophotographic photoreceptor that has extremely good potential stability and retains good images.

A further object of the present invention is to provide an electrophotographic photoreceptor that has no memory for light even when exposed to visible light for a long time.

[Means for solving problems]

The present inventors focused on oxytitanium phthalocyanine as a charge-generating material and discovered a new crystal form.

That is, the present invention provides an electrophotographic photoreceptor having a photosensitive layer containing a charge-generating material and a charge-transporting material on a conductive support, wherein the charge-generating material has a Bragg angle of 2θ±0. 2° is 7.4°, 9
．． 2°, 10.4°, 11.6° 13.0'
14.3°15.0°, 15.5°. 23.4°,
24.1' This is an electrophotographic photoreceptor characterized by being an oxytitanium phthalocyanine crystal having strong peaks at 26.2° and 27.2°.

Here, the structure of oxytitanium phthalocyanine is represented by:

However, X+ T X2 + Xa + X4 represents CI or Br, and n, m, I! , is an integer from O to 4.

The method for producing oxytitanium phthalocyanine according to the present invention will be exemplified.

First, for example, titanium tetrachloride and orthophthalodinitrile are reacted in α-chlornaphthalene to obtain dichlorotitanium phthalocyanine. This is washed with a solvent such as α-chloronaphthalene, trichlorobenzene, dichlorobenzene, N-methylpyrrolidone, N,N-dimethylformamide, etc., then washed with a solvent such as methanol or ethanol, and then hydrolyzed with hot water. Oxytitanium phthalocyanine crystals are obtained. Since the crystals thus obtained are often a mixture of various polymorphs, they are converted into amorphous succinititanium phthalocyanine by treatment with an acid basting method.

Next, this amorphous oxytitanium phthalocyanine was added to
Milling at 0 to 200°C, preferably 60 to 120°C, and then adding a solvent such as cyclohexanone for 5 minutes to
Oxytitanium phthalocyanine crystals of the present invention can be obtained by treatment for 24 hours, preferably 15 minutes to 10 hours.

The X-ray diffraction pattern of the oxytitanium phthalocyanine crystal in the present invention has strong peaks at Bragg angles of 2θ±0.26 of 7.4°, 9.2°, 10.4°, 11.6°, 13.0°, 14.3 @15.0015.5°. 23
．． The peaks are located at 4° 24.1', 26, 2' and 27.2°, and the above peaks are obtained by selecting the top 16 points with the highest peak intensities. The specific diffraction pattern is shown in FIG. 1, for example.

Hereinafter, the typical layer structure of the electrophotographic photoreceptor of the present invention will be explained as follows.
As shown in FIG.

In FIG. 2, the photosensitive layer 1 consists of a single layer, and the photosensitive layer 1 contains a charge generating material 2 and a charge transporting material (not shown) at the same time.

Note that 3 is a conductive support.

In FIG. 3, the photosensitive layer 1 has a laminated structure of a charge generation layer 4 and a charge transport layer 5, and the charge generation layer 4 contains the charge generation material 2. In FIG.

Note that the stacking relationship between the charge generation layer 4 and the charge transport layer 5 shown in FIG. 3 may be reversed.

When producing the electrophotographic photoreceptor of the present invention, the conductive support 3 may be any material as long as it has conductivity, such as metals such as aluminum and stainless steel, metals provided with a conductive layer, plastics, and paper. Examples of the shape include a cylindrical shape or a film shape.

Furthermore, a subbing layer having barrier and adhesive functions may be provided between the conductive support 3 and the photosensitive layer l.

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

These are dissolved in a suitable solvent and applied onto a conductive support. The film thickness is 0.2 to 3.0 μm.

When forming a photosensitive layer consisting of a single layer as shown in FIG. 2, it can be obtained by mixing the oxytitanium phthalocyanine charge generating material and charge transporting material of the present invention in a suitable binder resin solution, coating and drying.

The charge generating layer of the photosensitive layer having a laminated structure as shown in FIG. 3 can be formed by dispersing the oxytitanium phthalocyanine charge generating material of the present invention together with a suitable binder resin solution, coating and drying. In this case, the binder resin may also be used.

Examples of the binder resin used here include polyester resin, acrylic resin, polyvinyl carbazole resin, phenoxy resin, polycarbonate resin, polyvinyl butyral resin, polystyrene resin, polyvinyl acetate resin, polysulfone resin, polyarylate resin, and vinylidene chloride/acrylonitrile resin. Polymer resins and the like are mainly used.

The charge transport layer is mainly formed by applying and drying a paint 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, and triallylmethane compounds.

Moreover, as the binder resin, those mentioned above can be used.

Coating methods for these photosensitive layers include dipping,
Spray coating method, spinner coating method,
A bead coating method, a blade coating method, a beam coating method, etc. can be used.

When the photosensitive layer is a single layer, the appropriate film thickness is 5 to 40 μm, preferably 10 to 30 μm.

Further, when the photosensitive layer has a laminated structure, the thickness of the charge generation layer is 0.
01 to 10 μm, preferably 0.05 to 5 μm, and the thickness of the charge transport layer is 5 to 40 μm, preferably 1
It is in the range of 0 to 30 μm.

Furthermore, in order to protect these photosensitive layers from external impact, a thin protective layer may be provided on the surface of the photosensitive layer.

When the oxytitanium phthalocyanine crystal of the present invention is used as a charge-generating material, it can be mixed with other charge-generating materials depending on the purpose.

Next, a synthesis example of oxytitanium phthalocyanine crystals used in the present invention will be shown.

Hereinafter, parts refer to parts by weight.

[Synthesis Example 1] In 100 parts of α-chlornaphthalene, 5.0 parts of 0-phthalodinitrile and 13.6 parts of titanium tetrachloride were mixed at 200°C with 3 parts of
After heating and stirring for an hour, the mixture was cooled to 50° C., and the precipitated crystals were filtered off to obtain a paste of dichlorotitanium phthalocyanine. Next, this was heated to 100℃ N, N'
- Washing with 100 parts of dimethylformamide with stirring, then washing twice with 100 parts of methanol at 60°C was repeated, followed by filtration. Further, the obtained paste was diluted with deionized water for 10 minutes.
The mixture was stirred at 80° C. for 1 hour and filtered to obtain blue oxytitanium phthalocyanine crystals.

The elemental analysis values of this compound were as follows.

Elemental analysis value (C32H+a Nls TiO) CHN
(J! Calculated value (%) 66.68 2.80 19.4
4 0.00 Actual value (%) 66.50 2.9
9 19.42 0.47 Next, the crystals were dissolved in concentrated sulfuric acid 3
The solution was dissolved in 300 parts of deionized water at 20° C. under stirring, reprecipitated, and filtered to obtain amorphous oxytitanium phthalocyanine. 10 parts of the amorphous oxytitanium phthalocyanine thus obtained were mixed with 15 parts of sodium chloride and 7 parts of diethylene glycol,
Milling treatment was performed for 60 hours in an automatic mortar under heating at 80°C. Next, sufficient water washing was performed to completely remove the sodium chloride and diethylene glycol contained in this treated product. After drying this under reduced pressure, 200 parts of cyclohexanone and 1 mm diameter glass beads were added and processed in a sand mill for 30 minutes to obtain novel oxytitanium phthalocyanine crystals of the present invention. The X-ray diffraction pattern of this oxytitanium phthalocyanine crystal is shown in FIG.

[Comparative Synthesis Example 1] JP-A No. 61-239248 (USP 4,728,
592), the so-called α
An oxytitanium phthalocyanine crystal called a type was obtained.

This X-ray diffraction diagram is shown in FIG.

[Comparative Synthesis Example 2] JP-A-62-67094 (USP 4,664,9
According to the synthesis example disclosed in 97), oxytitanium phthalocyanine crystals, so-called type A, were obtained.

This X-ray diffraction diagram is shown in FIG.

[Comparative Synthesis Example 3] According to the synthesis example disclosed in JP-A-64-17066, an oxytitanium phthalocyanine crystal having the same crystal type as that of JP-A-64-17066 was obtained.

This X-ray diffraction diagram is shown in FIG.

In addition, the measurement of the X-ray diffraction pattern in the present invention was carried out using CuKa rays under the following conditions.

Measuring device used: Rigaku Denki X-ray diffraction device X-ray bulb: Cu Voltage: 50KV Current: 40mA Scan method = 2θ/θ scan Sampling interval: 0.020 deg.

Start angle (2θ): 3 deg.

Stop angle (2θ): 40 deg.

Divergence slit: 0.5 deg.

Scattering slit: 0,5 deg.

Receiving slit: 0.3 mm Using a curved monochromator The electrophotographic photoreceptor of the present invention is widely used not only in printers such as laser beam printers, LED printers, and CRT printers, but also in ordinary electrophotographic copying machines and other electrophotographic application fields. Can be applied.

[Example 1] 50 parts of titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of resol type phenolic resin
1 part, 20 parts of methyl cellosolve, 5 parts of methanol, and 0.002 parts of silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, average molecular weight 3000) were dispersed for 2 hours in a sand mill apparatus using φ1 mm glass beads to obtain conductivity. A layer paint was prepared.

Aluminum cylinder (φ30 mm x 260
The above-mentioned paint was applied by dip coating on M m ) and dried at 140° C. for 30 minutes to form a conductive layer with a thickness of 20 μm.

On top of this, a solution of 5 parts of 6-66-610-12 quaternary polyamide copolymer resin dissolved in a mixed solvent of 70 parts of methanol and 25 parts of butanol was applied by dipping and dried to form a 1 μm thick undercoat layer. Established.

Next, 4 parts of oxytitanium phthalocyanine crystals obtained in Synthesis Example 1 of the present invention and 2 parts of polyvinyl butyral resin were added to 100 parts of cyclohexanone and dispersed for 2 hours in a sand mill using 1 mm diameter glass beads.
0 parts of methyl ethyl ketone was added, diluted and recovered, and this was coated on the undercoat layer and dried at 80° C. for 10 minutes to form a charge generation layer with a thickness of 0.15 μm.

Next, a solution was prepared by dissolving 10 parts of a charge transport material represented by the following structural formula and 10 parts of bisphenol Z type car recarbonate resin in 60 parts of monochlorobenzene, and the solution was applied onto the charge generation layer by a dipping method. This was dried at a temperature of 110° C. for 1 hour to form a charge transport layer with a thickness of 20 μm.

[Comparative Example 1] An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that α-type oxytitanium phthalocyanine obtained in Comparative Synthesis Example 1 was used.

[Comparative Example 2] An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that type A oxytitanium phthalocyanine obtained in Comparative Synthesis Example 2 was used.

[Comparative Example 3] An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that oxytitanium phthalocyanine having the same crystal type as that of JP-A-64-17066 obtained in Comparative Synthesis Example 3 was used.

These Example 1 and Comparative Examples 1.2.3 were installed in a laser beam printer (product name: LBP-SX: manufactured by Canon), and charging was set so that the dark area potential was -700 (V). A laser beam with a wavelength of 802 nm was irradiated, and the amount of light required to lower the potential of Qi 700 (V) to -150 (V) was measured and defined as the sensitivity.

The results are shown in Table 1.

Table 1 Next, these four types of photoreceptors were measured at a dark potential of -700 (V).
, 400 volts continuously with the bright area potential set to -150 (V)
A 0-sheet paper running durability test was conducted, and after the durability test, the potentials of dark areas and bright areas were measured and the image was evaluated.

Figure 7 shows the state of dark area potential fluctuation due to paper feeding durability, and Figure 8 shows the state of contrast potential fluctuation between dark area potential and bright area potential.
As shown in the figure.

As is clear from the results shown in Figures 1 and 2, in Example 1, a good image equivalent to the initial image was obtained even after durability, but in Comparative Example 1.2.3, the ground strength in the white area was Blurring occurred, and was particularly noticeable in Comparative Example 3.

In addition, in Comparative Examples 1, 2, and 3, when the density was adjusted using the density adjustment lever to remove soil blur, the density of the black background portion was insufficient.

Next, the same photoreceptors as in Example 1 and Comparative Examples 1.2.3 were each used.
After preparing this photoconductor and irradiating a part of each photoreceptor with white light of 1500 lux for 30 minutes, it is installed in the laser beam printer and the dark potential of the part not irradiated with white light is set to -700 (V). The difference between the irradiated area and the irradiated area was measured. The results are shown in Table 2.

Table 2 shows stable high sensitivity characteristics in the long wavelength region around 810 nm.

[Example 2] An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that bisphenol 2 type polycarbonate resin was used as the binder resin of the charge generation layer.

[Example 3] The charge transport material had the following structural formula. FIG. 9 shows the distribution of spectral sensitivity in the electrophotographic photoreceptor of Example 1 when the maximum value of spectral sensitivity is 100.

As described above, an electrophotographic photoreceptor of the present invention was prepared in the same manner as in Example 1 except that the compounds represented by 770 and above were used.

[Example 4] An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that a compound represented by the following structural formula was used as the charge transport material.

Regarding Example 2.3.4, the surface potential was changed from -700 (V) to -15 using a laser beam printer as in Example 1.
The amount of light required to change the voltage to 0 (V) was measured and defined as the sensitivity. The results are shown in Table 3.

Table 3 [Example 5] A subbing layer similar to that in Example 1 was formed using a bar code on an aluminum sheet substrate having a thickness of 50 μm, and a charge transport layer similar to that in Example 1 was further formed on this to a thickness of 20 μm. Form.

Next, 5 parts of bisphenol Z-type car recarbonate were dissolved in 68 parts of cyclohexanone, 3 parts of oxytitanium phthalocyanine crystals showing the X-ray diffraction pattern obtained in Synthesis Example 1 were mixed with this solution, and the mixture was milled in a sand mill for 1 hour. After time dispersion, 5 parts of bisphenol 2 type polycarbonate and 10 parts of the charge transport material used in Example 1 were dissolved, and 40 parts of tetrahydrofuran and 40 parts of dichloromethane were further added to dilute the solution to obtain a dispersed paint. This paint was applied onto the charge transport layer by a spray coating method and dried to form a charge generation layer with a thickness of 6 μm.

[Comparative Example 4] An electrophotographic photoreceptor was prepared in the same manner as in Example 5, except that α-type oxytitanium phthalocyanine obtained in Comparative Synthesis Example 1 was used as the charge-generating material.

[Comparative Example 5] An electrophotographic photoreceptor was prepared in the same manner as in Example 5, except that the A-type oxytitanium phthalocyanine obtained in Comparative Synthesis Example 2 was used as the charge-generating material.

[Comparative Example 6] JP-A-64 obtained in Comparative Synthesis Example 3 as a charge generating material
An electrophotographic photoreceptor was prepared in the same manner as in Example 5, except that oxytitanium phthalocyanine having the same type of crystal as No. 17066 was used.

The thus obtained electrophotographic photoreceptors of Example 5 and Comparative Examples 4, 5, and 6 were evaluated using an electrostatic tester (EPA-8100 + Kawaguchi Denki type).

The evaluation begins with a surface potential of 700 due to positive corona charging.
(V), and then exposed to monochromatic light of 802 nm separated by a monochromator, and the amount of light when the surface potential decreased to 200 (V) was measured, and the sensitivity was determined. The results are shown in Table 4.

Table 4 [Effects of the present invention] As described above, an electrophotographic photoreceptor using the oxytitanium phthalocyanine crystal of the present invention as a charge generating material has the following properties:
It exhibits extremely high sensitivity to long wavelength light, and there is no potential fluctuation such as decrease in charging ability even during continuous use.
It has excellent potential stability and also has good optical memory characteristics against white light.

[Brief explanation of drawings]

FIG. 1 is an X-ray diffraction diagram of the oxytitanium phthalocyanine crystal of the present invention, FIGS. 2 and 3 are schematic cross-sectional views of the layer structure of the electrophotographic photoreceptor, and FIGS. 4, 5, and 6 are An X-ray diffraction diagram of the oxytitanium phthalocyanine crystal obtained in the comparative synthesis example, Fig. 7 is a diagram showing the state of dark area potential fluctuation due to paper running durability obtained in the example, and Fig. 8 is a diagram showing the state of dark area potential fluctuation obtained in the example. FIG. 9 is a diagram showing the spectral sensitivity of the electrophotographic photoreceptor of Example 1. FIG.

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer containing a charge-generating material and a charge-transporting material on a conductive support, the charge-generating material has a Bragg angle of 2θ±0.2° in the X-ray diffraction spectrum of CuKα. 7.4°, 9.2°, 10.
4°, 11.6°, 13.0°, 14.3°, 15.0
゜, 15.5゜. An electrophotographic photoreceptor characterized in that it is an oxytitanium phthalocyanine crystal having strong peaks at 23.4°, 24.1°, 26.2° and 27.2°.