JPH0655907B2 - Novel crystalline form of oxytitanium phthalocyanine and electrophotographic photoreceptor using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel crystalline form of oxytitanium phthalocyanine and an electrophotographic photoreceptor using the same.

[Conventional technology]

Conventionally, phthalocyanine pigments have been attracting attention and studied as electronic materials used for electrophotographic photoreceptors, solar cells, sensors and the like, as well as for coloring.

Further, in recent years, non-impact printers to which electrophotographic technology is applied have become widespread in place of conventional impact printers as terminal printers. These are mainly laser beam printers using a laser beam as a light source, and as the light source, a semiconductor laser is used in terms of cost, size of the device, and the like.

Currently, semiconductor lasers that are mainly used have an oscillation wavelength of 790 ± 20 nm, which is a long wavelength. Therefore, development of an electrophotographic photosensitive member having sufficient sensitivity to light of these long wavelengths has been advanced.

The sensitivity on the long wavelength side varies depending on the type of charge generating material, and many charge generating materials have been studied.

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

On the other hand, as charge generating materials having sensitivity to long-wavelength light, research on metal phthalocyanines such as aluminum chlorophthalocyanine, chloroindium phthalocyanine, oxyvanadyl phthalocyanine, chlorogallium phthalocyanine, magnesium phthalocyanine, and oxytitanium phthalocyanine or metal-free phthalocyanines has recently been conducted. Has been done a lot.

Of these, many phthalocyanine compounds are known to have polymorphism. For example, metal-free phthalocyanine has α-form,
There are β-type, γ-type, δ-type, ε-type, x-type, τ-type, etc. Among copper phthalocyanines, α-type, β-type, γ-type, δ-type, ε-type, x-type and the like are generally known.

It is also generally known that the difference in crystal form greatly affects electrophotographic properties (sensitivity, potential stability during durability, etc.) and paint properties when made into a paint.

In particular, regarding oxytitanium phthalocyanine having high sensitivity to long-wavelength light, there are polymorphs like other phthalocyanines such as metal-free phthalocyanine and copper phthalocyanine as described above. For example, JP-A-59-49544 (USP4,444,861), JP-A-59-166959, JP-A-61-239248 (USP4,728,592), JP-A-62-6709
4 (USP 4,664,997), JP-A-63-366, JP-A-63-116158, JP-A-63-198067 and JP-A-64-17066, each having a different crystal form. Oxytitanium phthalocyanine has been reported.

[Problems to be solved by the invention]

The main object of the present invention is to provide a novel crystalline form of oxytitanium phthalocyanine different from these previously reported crystalline forms.

Another object of the present invention is to provide an electrophotographic photosensitive member having extremely high photosensitivity to long wavelength light.

Further, the purpose of the present invention, when repeated durability,
It is an object of the present invention to provide an electrophotographic photosensitive member having extremely good potential stability and holding a good image.

Further, it is an object of the present invention to provide an electrophotographic photosensitive member having no memory for light even when it is irradiated with visible light for a long time.

[Means for solving problems]

As a result of research on oxytitanium phthalocyanine, the present inventors have found a novel crystal form whose X-ray diffraction spectrum is different from any of the conventionally known ones, and further, an electrophotographic photoreceptor using this crystal form of oxytitanium phthalocyanine has excellent electron It has been found to exhibit photographic properties.

That is, the present invention is a novel crystalline form of oxytitanium phthalocyanine having strong peaks at Bragg angles 2θ ± 0.2 ° of 4.8 °, 9.6 ° and 26.2 ° in X-ray diffraction of CuK _α .

Further, the present invention is an electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer has a Bragg angle 2θ ± 0.2 ° of 4.8 ° and 9.6 ° in X-ray diffraction of CuK _α. And an electrophotographic photoconductor characterized by containing crystalline oxytitanium phthalocyanine having a strong peak at 26.2 °.

Hereinafter, the present invention will be described in detail.

The X-ray diffraction pattern of oxytitanium phthalocyanine in the present invention is as shown in FIG.
Strong peaks are shown at 4.8 °, 9.6 ° and 26.2 ° (± 0.2 °). The above peaks are the top three peaks with the highest peak intensity, and are the main peaks.

The characteristic of the X-ray diffraction diagram of FIG. 1 is that the peak at 26.2 ° is the strongest among the peaks at the above three points, and the peaks weaker than the above three points are at the positions at 13.0 ° and 28.8 °. That is.

In the present invention, the peak shape of X-ray diffraction is slightly different due to the difference in the conditions at the time of manufacture, the measurement conditions, etc., and the tip of each peak may be split.

Where the structure of oxytitanium phthalocyanine is It is represented by.

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

The method for producing crystalline oxytitanium phthalocyanine of the present invention will be exemplarily described.

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, and then with a solvent such as methanol and ethanol, and then hydrolyzed with hot water. Oxytitanium phthalocyanine crystals are obtained. The crystals thus obtained are often a mixture of various polymorphs, and it is usually difficult to obtain the crystalline form of oxytitanium phthalocyanine of the present invention by treating this mixture. Therefore, in the present invention, it is converted into amorphous oxytitanium phthalocyanine by a treatment by an acidic pacing method.

Next, the obtained amorphous oxytitanium phthalocyanine was mixed with α-chloronaphthalene, α-bromonaphthalene, α-
By performing a dispersion treatment using a solvent such as fluoronaphthalene as a dispersion medium, the crystalline oxytitanium phthalocyanine of the present invention can be obtained.

The thus-obtained oxytitanium phthalocyanine crystal has an excellent function as, for example, a photoconductor, and can be applied to electronic materials such as electrophotographic photoreceptors, solar cells, sensors, and switching elements.

Hereinafter, an example of applying the oxytitanium phthalocyanine crystal of the present invention as a charge generating material in an electrophotographic photoreceptor will be described.

First, a typical layer structure of an electrophotographic photoreceptor is shown in FIGS. 2 and 3.

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

In addition, 3 is a conductive support.

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

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

In the case of manufacturing an electrophotographic photosensitive member, the conductive support 3 may be any one having conductivity, and may be a metal such as aluminum or stainless steel, or a metal provided with a conductive layer, plastic, paper, or the like. Examples thereof include a cylindrical shape and a film shape.

An undercoat layer having a barrier function and an adhesive function may be provided between the conductive support 3 and the photosensitive layer 1.

Examples of the material for the undercoat layer include polyvinyl alcohol, polyethylene oxide, ethyl cellulose, methyl cellulose, casein, polyamide, glue, gelatin and the like.

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

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

A method for forming the charge generating layer of the photosensitive layer having a laminated structure as shown in FIG. 3 is obtained 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 be omitted.

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

The charge transport layer is mainly formed by coating 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, the above-mentioned thing can be used as a binder resin.

As the coating method of these photosensitive layers, a dipping method,
Spray coating method, spinner coating method,
A bead coating method, a blade coating method, a beam coating method or the like can be used.

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

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 10 to 30 μm.

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

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

Such an electrophotographic photoreceptor can be widely applied not only to printers such as laser beam printers, LED printers and CRT printers, but also to ordinary electrophotographic copying machines and other electrophotographic application fields.

Next, a production example of the oxytitanium phthalocyanine crystal of the present invention will be shown.

[Production Example 1] In 100 g of α-chlornaphthalene, 5.0 g of o-phthalodinitrile and 2.0 g of titanium tetrachloride were heated and stirred at 200 ° C for 3 hours, then cooled to 50 ° C and the precipitated crystals were filtered. Separately, a paste of dichlorotitanium phthalocyanine was obtained. Next, this was washed with 100 ml of N, N′-dimethylformamide heated to 100 ° C. under stirring, and then washed twice with 100 ml of methanol at 60 ° C., and separated by filtration. Furthermore,
The resulting paste was mixed with 100 ml of deionized water at 80 ° C for 1 hour.
After stirring for an hour and filtering, blue oxytitanium phthalocyanine crystals were obtained. Yield 4.3g.

The elemental analysis values of this compound were as follows.

Elemental analysis value (C ₃₂ H ₁₆ N ₈ TiO) Next, the crystals were dissolved in 30 ml of concentrated sulfuric acid, added dropwise to 300 ml of deionized water at 20 ° C. under stirring to reprecipitate, filtered, and thoroughly washed with water to obtain amorphous oxytitanium phthalocyanine. 100 g of α-chloronaphthalene was added to 4.0 g of the amorphous oxytitanium phthalocyanine thus obtained, and the dispersion treatment was carried out for 20 hours with a paint shaker using φ1 mm glass beads, and then thoroughly washed, After drying, a novel crystalline oxytitanium phthalocyanine of the present invention was obtained. Yield 3.7g. The X-ray diffraction pattern of this oxytitanium phthalocyanine is shown in FIG.

[Comparative Production Example 1] According to the production example disclosed in JP-A-61-239248 (USP 4,728,592), a crystalline form of oxytitanium phthalocyanine, which is so-called α-type, was obtained.

This X-ray diffraction pattern is shown in FIG.

[Comparative Production Example 2] According to the production example disclosed in JP-A-62-67094 (USP 4,664,997), a crystalline form of oxytitanium phthalocyanine called so-called A type was obtained.

This X-ray diffraction pattern is shown in FIG.

[Comparative Production Example 3] Oxytitanium phthalocyanine having the same crystal form as in JP-A-64-17066 was obtained according to the production example disclosed in JP-A-64-17066.

This X-ray diffraction pattern is shown in FIG.

The X-ray diffraction pattern in the present invention was measured using CuK _α rays under the following conditions.

Measuring instrument used: X-ray diffractometer RAD-A system made by Rigaku Denki X-ray tube: Cu Tube voltage: 50kV Tube current: 40mA Scanning method: 2θ / θ scanning Scanning speed: 2deg./min Sampling interval: 0.020deg. Start angle (2θ): 3 deg. Stop angle (2θ): 40 deg. Divergence slit: 0.5 deg. Skirting slit: 0.5 deg. Receiving slit: 0.3 mm Using a curved monochromator. An example in which a crystalline form of oxytitanium phthalocyanine is applied to an electrophotographic photoreceptor is shown. In addition, a part shows a weight part.

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

On an aluminum cylinder (φ30mm × 260mm),
Apply the above coating by dipping and dry at 140 ° C for 30 minutes to obtain a film thickness of 2
A conductive layer of 0 μm was formed.

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 a dipping method and dried to form a 1 μm thick undercoat layer. Provided.

Next, 4 parts of crystalline oxytitanium phthalocyanine obtained in Production Example 1 of the present invention and 2 parts of polyvinyl butyral resin were added to 100 parts of cyclohexanone and dispersed for 1 hour in a sand mill using 1 mmφ glass beads. 100
Part of methyl ethyl ketone was added to dilute it, and this was coated on the undercoat layer and then dried at 80 ° C for 10 minutes to give a film thickness of 0.15μ.
m charge generating layer was formed.

Next, the following structural formula A solution was prepared by dissolving 10 parts of the charge-transporting material and 10 parts of a bisphenol Z-type polycarbonate resin in 60 parts of monochlorobenzene, and applied on the charge generation layer by the dipping method. This is dried at 110 ℃ for 1 hour and 20μ
An m-thick charge transport layer was formed to manufacture an electrophotographic photoreceptor.

Comparative Example 1 An electrophotographic photosensitive member was produced in the same manner as in Example 1 using the α-type oxytitanium phthalocyanine obtained in Comparative Production Example 1.

Comparative Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the A-type oxytitanium phthalocyanine obtained in Comparative Production Example 2 was used.

[Comparative Example 3] An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that oxytitanium phthalocyanine having the same crystal form as in JP-A No. 64-17066 obtained in Comparative Production Example 3 was used.

The electrophotographic photoconductors of Example 1 and Comparative Examples 1, 2, and 3 were installed in a laser beam printer (trade name: LBP-SX: made by Canon), and charged so that the dark potential was −700 (V). The sensitivity was set by measuring the amount of light required to lower the potential of -700 (V) to -150 (V) by irradiating it with laser light having a wavelength of 802 nm.

The results are shown in Table 1.

Next, these four types of photoconductors were subjected to a continuous paper passing durability test of 4,000 sheets under the condition that the dark part potential was −700 (V) and the light part potential was −150 (V). The potential was measured and the image was evaluated.

FIG. 7 shows the state of fluctuation of the dark potential due to paper running durability, and FIG. 8 shows the state of fluctuation of the contrast potential between the dark potential and the bright potential.
Shown in the figure.

As is clear from the results of FIG. 7 and FIG. 8, in Example 1, a good image equivalent to the initial stage was obtained even after the endurance, but in Comparative Examples 1, 2, and 3, the background was white. Fog was caused, and it was particularly remarkable in Comparative Example 3.

Further, in Comparative Examples 1, 2, and 3, when the density adjustment lever was used to remove the background fog, the density of the black background became insufficient.

Next, the same photoconductors as in Example 1 and Comparative Examples 1, 2, and 3 were used.
Prepare this, irradiate a part of each photoconductor with white light of 1500 lux for 30 minutes, then install it in the laser beam printer and set the dark part potential of the part not irradiated with white light to −
The difference from the irradiated portion when set to 700 (V) was measured.
The results are shown in Table 2.

Note that FIG. 9 shows the distribution of the spectral sensitivity when the maximum spectral sensitivity of the electrophotographic photosensitive member of Example 1 is 100.

As described above, the electrophotographic photosensitive member of the present invention exhibits stable high sensitivity characteristics in the long wavelength region around 770 to 810 nm.

[Example 2] An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that a bisphenol Z-type polycarbonate resin was used as the binder resin of the charge generation layer and monochlorobenzene was used instead of cyclohexanone. did.

Example 3 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that bisphenol Z-type polycarbonate resin was used as the binder resin for the charge generation layer.

Example 4 As the charge transport material, the following structural formula An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the compound shown in 1 was used.

Example 5 As the charge transport material, the following structural formula An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the compound shown in 1 was used.

For Examples 2, 3, 4, and 5, the surface potential was changed from -700 (V) to -150 with a laser beam printer as in Example 1.
The amount of light required to change to (V) was measured and used as the sensitivity.
The results are shown in Table 3.

Example 6 An undercoat layer similar to that of Example 1 was formed by bar coating on an aluminum sheet substrate having a thickness of 50 μm, and a charge transport layer similar to that of Example 1 was further formed thereon to a thickness of 20 μm.

Next, 5 parts of bisphenol Z type polycarbonate was dissolved in 68 parts of cyclohexanone, and 3 parts of the oxytitanium phthalocyanine crystal showing the X-ray diffraction pattern obtained in Production Example 1 was mixed with this solution, and dispersed in a sand mill for 1 hour. After that, 5 parts of bisphenol Z-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 added and diluted to obtain a dispersion paint. This paint was applied onto the charge transport layer by a spray coating method and dried to form a charge generating layer having a thickness of 6 μm, thus producing an electrophotographic photoreceptor.

Comparative Example 4 An electrophotographic photosensitive member was produced in the same manner as in Example 6 except that the α-type oxytitanium phthalocyanine obtained in Comparative Production Example 1 was used as the charge generation material.

Comparative Example 5 An electrophotographic photosensitive member was produced in the same manner as in Example 6 except that the A-type oxytitanium phthalocyanine obtained in Comparative Production Example 2 was used as the charge generation material.

[Comparative Example 6] Japanese Patent Application Laid-Open No. 64-64, which was obtained in Comparative Production Example 3 as a charge generating material.
An electrophotographic photosensitive member was produced in the same manner as in Example 6 except that oxytitanium phthalocyanine having the same crystal type as 17066 was used.

The electrophotographic photoreceptors of Example 6 and Comparative Examples 4, 5 and 6 thus obtained were subjected to an electrostatic tester (EPA-8100: manufactured by Kawaguchi Electric Co., Ltd.).
Was evaluated.

The evaluation is that the surface potential is 700 (V) due to positive corona charging at first.
And then exposed with monochromatic light of 802 nm separated by a monochromator to obtain a surface potential of 200 (V).
The amount of light when it went down was measured and used as the sensitivity. The results are shown in Table 4.

[Effects of the Invention] As described above, the crystalline form of oxytitanium phthalocyanine of the present invention is novel, and its usefulness is clear.
In addition, the electrophotographic photosensitive member using this novel crystalline form of oxytitanium phthalocyanine as a charge generating material exhibits extremely high sensitivity to long-wavelength light and has potential fluctuations such as deterioration of charging ability even in continuous use. It is excellent in potential stability and has good optical memory characteristics for white light.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction diagram of the crystalline oxytitanium phthalocyanine crystal of the present invention obtained in the production example, FIGS. 2 and 3 are schematic cross-sectional views of the layer structure of the electrophotographic photoreceptor, and FIG. 5 and 6 are X-ray diffraction patterns of the crystalline form of oxytitanium phthalocyanine obtained in the comparative production example, and FIG. 7 shows the dark potential variation due to the paper passing durability obtained in the examples. FIG. 8 is a diagram showing the state of fluctuations in contrast potential due to paper passing durability obtained in Examples, and FIG. 9 is a diagram showing the spectral sensitivity of the electrophotographic photosensitive member of Example 1.

Claims (2)

[Claims] 1. Bragg angle 2θ in X-ray diffraction of CuK _α
A novel crystalline form of oxytitanium phthalocyanine having strong peaks at ± 0.2 ° at 4.8 °, 9.6 ° and 26.2 °. 2. An electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has a Bragg angle 2θ ± 0.2 ° in X-ray diffraction of CuK _α of 4.8 °, 9.6 ° and 2
An electrophotographic photoreceptor containing crystalline oxytitanium phthalocyanine having a strong peak at 6.2 °.