JPH0719067B2 - Electrophotographic photoconductor - Google Patents

Description

The present invention relates to an electrophotographic apparatus, and more particularly to an electrophotographic photoreceptor having high sensitivity in the near infrared region used in a laser beam printer using a semiconductor laser as a recording light source and a laser plate making system.

In recent years, there have been significant advances in semiconductor lasers, but the ones that have been put into practical use are those whose oscillation wavelength is longer than 780 nm, and are mainly used as light sources for printers or plate-making systems at 780 nm to 850 nm. The one with the oscillation wavelength is used.

At present, the output of semiconductor lasers is weaker than that of other lasers, so the photoconductors used in semiconductor laser printers and semiconductor laser plate making systems have sufficiently high sensitivity in the region of 780 to 850 nm (for example, half exposure dose of 10 erg / cm). ² or less) is required.

Conventionally, as electrophotographic photoreceptors, inorganic compounds such as selenium, selenium tellurium, cadmium sulfide and zinc oxide,
Alternatively, organic compounds such as poly-N-vinylcarbazole (PVK), perylene pigments, anzantron pigments and disazo pigments are used.

However, these have insufficient photosensitivity in the long wavelength region of 780 nm to 850 nm. In recent years, it has been reported that the photosensitivity of alloys of selenium, tellurium, and arsenic, or the photosensitization of dyes sensitized with cadmium sulfide, improves the sensitivity in the long wavelength region around 800 nm. Therefore, there is a problem in safety in manufacturing and handling the photoconductor, and there is a problem in environmental pollution. Further, the amorphous silicon type photoconductor can be made into a photoconductor having sensitivity in a long wavelength region by a specific doping method and a producing method, but at this stage, the film forming speed is slow and there is a problem in mass productivity. It is hard to say that it is a low-cost photoconductor.

Phthalocyanine compounds have been extensively studied as compounds having high sensitivity in the long wavelength region, but among the phthalocyanine compounds, compounds showing high sensitivity in the long wavelength region of 780 nm or more are χ-type metal-free phthalocyanine ( χ-H ₂ Pc), ε-type copper phthalocyanine (ε-CuPc), vanadyl phthalocyanine (VOPc), titanyl phthalocyanine (TiOPc), etc.

On the other hand, in order to improve the sensitivity, a laminated-type photoreceptor using a vapor-deposited film of phthalocyanine as a charge generation layer has been studied, and IIIa and IV
Among the metal phthalocyanines whose group metals are central metals, those having relatively high sensitivity have been obtained. However, the production of the vapor-deposited film requires a high-vacuum exhaust device, and the equipment cost is high, and the mass productivity of the organic photoconductor and the production cost for producing a large-area photoconductor are high.

Further, regarding the characteristics of the phthalocyanine compound-resin dispersion type photoreceptor, a photoreceptor using a phthalocyanine compound which is generally commercially available or obtained by a general production method is
760 to 860nm Half-wave exposure at each wavelength in the long wavelength range is 10
Until now, no one has shown high sensitivity below erg / cm ² .

In the long wavelength region of 760 to 860 nm, the present inventors have found that the half-exposure amount is 10 erg / cm ² or less in the high sensitivity region of the phthalocyanine compound.
As a result of intensive studies on the physical properties of magnesium phthalocyanine compounds as Group II metal phthalocyanine compounds, production method and treatment method, and crystal form for the purpose of producing a resin dispersion type photoreceptor, a pigment binder was found among these metal phthalocyanines. We have found a pigment that can realize a highly sensitive electrophotographic photoreceptor using a dispersion system.

The present invention is a photosensitive layer formed by dispersing a magnesium phthalocyanine compound or its derivative showing a strong peak at a Bragg angle 2θ of 18 °, 20 °, 21 °, 23 ° and 31 ° in a binder in an X-ray diffraction pattern. And an electrophotographic photosensitive member.

The magnesium phthalocyanine compound used in the present invention has the formula Represents a phthalocyanine compound containing magnesium as a central metal, and its derivative is 4 in the above formula.
Represents a compound having a structure in which at least a part of each benzene nucleus is substituted with a halogen atom, a nitro group, an amino group, or an optionally substituted alkyl, aralkyl, or aryl group.

Magnesium phthalocyanine compounds and their derivatives showing a strong peak at a specific Bragg angle in the X-ray diffraction pattern used in the present invention include, for example, a mixture of magnesium chloride and phthalonitrile as a quinoline solvent or without solvent at 230 to 240 ° C. After heating with, the crude product obtained by passing unreacted materials etc. It is obtained by treating with a strongly basic compound represented by As a treatment method, for example, a crude product of a magnesium phthalocyanine compound and its derivative is heated and dissolved in a strongly basic compound of the general formula (I), and then the mixture is passed, purified by a recrystallization method, and then dried by heating. The magnesium phthalocyanine compound and its derivative used in the present invention are thus obtained.

The magnesium phthalocyanine compound and its derivative obtained by the treatment using the general formula (I) can be dispersed as they are in a resin to be used for preparing a photoreceptor having high sensitivity in the near infrared region. Further, a magnesium phthalocyanine compound and its derivative treated by the recrystallization method or the like can be made into fine particles by using an appropriate mechanical means (attritor, ball milling, etc.) to prepare a photoreceptor having a higher charge accepting property. it can.

As the compound represented by the general formula (I) used in the present invention, any of amine-based, amide-based, imine-based and imide-based compounds can be applied.

Specific examples include methylamine, ethylamine, butylamine, pentylamine, hexylamine, peptylamine, octylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, morpholine, piperidine, pyridine, quinoline, indoline, dimethylformamide (DMF), diethylenetriamide, Examples include triethanolamine, diethanolamine, toluidine, 2-methylpyrrolidone and the like.

The treatment method using such a solvent can be carried out in the temperature range from room temperature to the boiling point of the solvent.

FIG. 1 is an X-ray diffraction diagram (b) of magnesium phthalocyanine before the recrystallization treatment from the solvent and an X-ray diffraction diagram (a) of magnesium phthalocyanine after the recrystallization treatment from the solvent. From these diffractograms 18 °, 20 °, 21
It can be seen that remarkably strong peaks at Bragg angles 2θ of °, 23 ° and 31 are caused by recrystallization from the compound of the general formula (I).

Other magnesium phthalocyanine compounds and their derivatives used in the present invention commonly have strong specific peaks as described above in their X-ray diffraction patterns, despite the difference in the substituents, their substitution positions or their substitution numbers. To be

The absorption layers in the visible region and the near infrared region are largely different between the photosensitive layer using magnesium phthalocyanine before the recrystallization treatment and the photosensitive layer using magnesium phthalocyanine after the recrystallization treatment.

FIG. 2 shows each absorption spectrum. These absorption spectra are measured by dispersing the magnesium phthalocyanine compound before and after the recrystallization treatment in a resin and coating the dispersion on a glass substrate. From this figure, it is understood that the photosensitive layer using the above-mentioned magnesium phthalocyanine compound and its derivative shows a sharp absorption peak at 800 to 820 nm.

Next, the photoconductivity of the magnesium phthalocyanine compound and its derivative used in the present invention will be described.

By simply dispersing this compound in an insulating resin and coating and drying it on a conductive substrate, a high charge-accepting property and sensitivity in the near infrared region can be increased as an electrophotographic photoreceptor.

Magnesium phthalocyanine compound powder obtained by a treatment method (including a recrystallization method) using a non-amine solvent has a small specific volume resistance and is hardly charged when dispersed in a resin to prepare a photoreceptor. From this, the effect of improving the chargeability and sensitivity of the resin dispersion type photoreceptor using the magnesium phthalocyanine compound and its derivative is counted as another feature of the present invention.

Therefore, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having photosensitivity in the near infrared region and improved charging ability and sensitivity.

The electrophotographic photoreceptor of the present invention can have various structures. Examples thereof are shown in FIGS. The photosensitive member shown in FIG. 3 is a photosensitive layer 2a in which a magnesium phthalocyanine compound and its derivative 3 are dispersed in a binder 4 on a conductive support 1.
Is provided. The photosensitive member shown in FIG. 4 is a conductive support 1.
A photosensitive layer 2b is provided on which a magnesium phthalocyanine compound and its derivative 3 are dispersed in a charge transport medium 5 composed of a charge transport substance and a binder. The photoreceptor of FIGS. 5 and 6 is a photosensitive layer comprising a charge carrier generation layer 6 mainly composed of a magnesium phthalocyanine compound and its derivative 3 and a charge transport layer 7 composed of a charge transport material and a binder.
2c or 2d is provided, respectively.

In the case of the photoreceptor shown in FIG. 3, the magnesium phthalocyanine compound and its derivative 3 have both functions of generating and transporting charge carriers necessary for light attenuation. In the case of the photoreceptor of FIG. 4, the charge transport substance forms the charge transport medium 5 together with the binder, while the magnesium phthalocyanine compound and its derivative 3 act as the charge carrier generating substance.
This charge transport medium 5 does not have the ability to generate charge carriers such as magnesium phthalocyanine compound and its derivatives,
It has the ability to accept and transport charge carriers generated from magnesium phthalocyanine compounds and their derivatives. That is, in the photoreceptor of FIG. 4, the charge carriers required for light attenuation are generated by the magnesium phthalocyanine compound and its derivative 3, while the charge carriers are mainly transported by the charge transport medium 5. In the case of the photoreceptor of FIGS. 5 and 6, the magnesium phthalocyanine compound and its derivative 3 contained in the charge carrier generation layer 6 generate charge carriers, while the charge transport layer 7 receives injection of charge carriers. Carry out the transportation. That is, the mechanism of action in which the charge carriers required for light attenuation are generated by the magnesium phthalocyanine compound and its derivative, and the charge carriers are transported by the charge transport medium is the same as in the case of the photoreceptor of FIG. .

The photoreceptor shown in FIG. 3 can be prepared by dispersing a magnesium phthalocyanine compound and its derivative in a binder solution, coating the dispersion on a conductive support, and drying. The photoreceptor shown in FIG. 4 can be prepared by dispersing a magnesium phthalocyanine compound and its derivative in a solution in which a charge transport material and a binder are dissolved, and coating the dispersion on a conductive support and drying. Further, the photoreceptor of FIG. 5 is obtained by applying a dispersion liquid obtained by dispersing fine particles of a magnesium phthalocyanine compound and its derivative in a solvent or a binder solution on a conductive support, and drying and then transporting the charge. It can be prepared by applying and drying a solution in which a substance and a binder are dissolved. The photoreceptor of FIG. 6 is obtained by applying a solution in which a charge transport material and a binder are dissolved onto a conductive support and drying it, and then adding fine particles of a magnesium phthalocyanine compound and its derivative into a solvent or a binder solution. It can be produced by applying a dispersion obtained by dispersion and drying. For coating, a roll coater, wire bar, doctor blade or the like is usually used.

The thickness of the photosensitive layer is, in the case of the photoconductor of FIGS. 3 and 4,
It is 3 to 50 μ, preferably 5 to 20 μ. Further, in the case of the photoreceptor of FIGS. 5 and 6, the thickness of the charge carrier generating layer is 5 μm or less, preferably 0.01 to 2 μm, and the thickness of the charge transport medium layer is 3 to 50 μm, preferably 5 μm. ~ 20μ. In the photoreceptor shown in FIG. 3, the proportion of the magnesium phthalocyanine compound and its derivative in the photosensitive layer is 10 to 70% by weight, preferably 30 to 50% by weight, based on the photosensitive layer. In the photoreceptor of FIG. 4, the proportion of the magnesium phthalocyanine compound and its derivative in the photosensitive layer is 1 to 50% by weight,
It is preferably 10 to 50% by weight, and the proportion of the charge transport material is 10 to 90% by weight, preferably 10 to 60% by weight. The proportion of the charge transport material in the charge transport medium layer of the photoreceptor of FIGS. 5 and 6 is 10 to 95% by weight, preferably 10 to 60% by weight. Note that a plasticizer can be used together with the binder in the production of any of the photoconductors shown in FIGS.

As the conductive support of the photoreceptor of the present invention, for example, a metal plate or metal foil such as aluminum, a plastic film on which a metal such as aluminum is vapor-deposited, or a paper subjected to a conductive treatment is used. As the binder, a vinyl polymer such as polystyrene, polyacrylamide, poly-N-vinylcarbazole, or a condensation resin such as a polyamide resin, a polyester resin, an epoxy resin, a phenoxy resin, or a polycarbonate resin is used, but it is supported by an insulating property. Any resin that adheres to the body can be used.

As the charge transporting substance, known substances can be used, for example, derivatives of heterocyclic compounds such as pyrazole, pyrazoline, oxadiazole, thiazole, imidazole, hydrazone derivatives, triphenylmethane derivatives, poly-N-vinylcarbazole and its derivatives. Etc. Of these, pyrazoline derivatives and hydrazone derivatives are particularly effective. In addition, these charge transport materials may be used alone or in combination of two or more.

In the photoreceptor obtained as described above, an adhesive layer or a barrier layer can be provided between the conductive support and the photosensitive layer, if necessary. Materials for these layers include polyamide,
Nitrocellulose, casein, polyvinyl alcohol, etc., and the film thickness is preferably 1 μm or less.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

Examples and Comparative Examples Example 1 100 g of phthalonitrile, hydrous magnesium chloride (MgCl ₂ .6H ₂
A mixture of 40 g of O) and 800 g of quinoline was refluxed at 230 ° C. for 2 hours and then filtered to obtain a solid. This solid is washed with methanol, warm water, and methanol in this order, and dried. 5 g of the crude product thus obtained are dissolved in 100 g of n-hexylamine at 130 ° C. under reflux for 1 hour and then heated. The liquid obtained is quenched and left to stand overnight for recrystallization. The crystals are roughly dried, crushed with a milk needle, and then re-dried (10
Perform 2 hours at 0 ℃. The magnesium phthalocyanine pigment produced by the above method is hereinafter referred to as Pigment A. To prepare an electrophotographic photoreceptor, 1 g of the above pigment A was mixed with 38 g of a polyester solution (chloroform solvent, 15% wt "AEP-01"; manufactured by Dainippon Ink and Chemicals, Inc.) with a paint checker. Use to disperse evenly. The finished paint is applied and dried on a PET film with aluminum deposited using a wire bar. The charging characteristics and photosensitivity of the electrophotographic photoreceptor thus prepared were measured. "Paper analyzer SP-428" (manufactured by Kawaguchi Electric Co., Ltd.) was used as a measuring machine.

The surface potential V ₀ (v) of the photoconductor immediately after applying each voltage of (+) 6 kV and (−) 6 kV to the photoconductor surface, and the surface potential V ₁₀ of the photoconductor 10 seconds after the voltage application is stopped ( v),
The charge retention ability of the photoconductor was evaluated by the value of V ₁₀ / V ₀ .

The sensitivity of the photoconductor was measured by exposing the surface of the charged photoconductor using a tungsten lamp of a white light source. Exposure amount E _1/2 (Lux.Sec) required to reduce the surface potential after exposure to half of the initial surface potential when the exposure intensity is 5 Lux
And the exposure amount E _1/2 (Lux.Sec) required to reduce the surface potential after exposure to 1/5 of the initial surface potential, and the surface potential V _R15 (v) at the time of 15 seconds after the start of exposure. The sensitivity of the photoconductor was evaluated based on the measured values. The results are summarized in Table 1.

Examples 2 to 12 Magnesium phthalocyanine compounds synthesized by the same synthetic method (quinoline method) as in Example 1 were subjected to rebinding treatment using various amine solvents. The characteristics of the electrophotographic photosensitive member using each magnesium phthalocyanine compound are summarized in Table 2.

Comparative Example 1 A photoconductor was prepared using the crude product obtained by the synthesis method of Example 1 (one that has not been subjected to recrystallization treatment with an amine solvent). The electrophotographic properties of this product are summarized in Table 3.

As is clear from this result, the magnesium phthalocyanine compound recrystallized with an amine solvent has high sensitivity.

FIG. 7 is a diagram showing the spectral sensitivity of the photoconductor of Example 1.
As is clear from the figure, the electrophotographic photosensitive member of the present invention is 500 n
The half-dose exposure from m to 900 nm was between ³ ergs / cm ² and ¹ ergs / cm ² .

Comparative Example 2 5 g of a magnesium phthalocyanine crude product is completely dissolved in 150 g of concentrated sulfuric acid at 0 ° C., then rapidly cooled and reprecipitated. The solid obtained is washed with distilled water until it is not acidic and then dried. A photoconductor was prepared in the same manner as in Example 1 and its electrophotographic characteristics were measured. E _1/2 was 1000 Lu
It was x.Sec. Furthermore, the charge acceptability of the photoreceptor in this case was small, which was 50V.

Example 13 50 g of magnesium phthalocyanine obtained by the treatment method of Example 1 was milled with 1 kg of stainless beads for 24 hours. Reflux 5 g of the finished pigment in diethyl ether for 30 minutes. The pigment obtained by repeating this operation 5 times is hereinafter referred to as Pigment B. Pigment B 150 parts by weight, hexamethylenediamine 1.5 parts by weight, polyester (AEP-01) 850 parts by weight, and epichlorohydrin 4820
2 parts by weight of the mixture of the composition is used with a paint shaker.
After being dispersed for a period of time, a 12 μm-thick photosensitive layer was applied and dried using a wire bar on an aluminum vapor-deposited PET film. When the electrophotographic characteristics were measured, the charge acceptance was +600 V, and the half-exposure amount E _1/2 = 1.0 Lux.Sec.

Comparative Example 3 A photosensitive layer was prepared in the same manner as in Example 13 except that hexamethylenediamine was not added. The charge acceptance of this photosensitive layer was + 20V. The half-exposure amount E _{1/2 was} > 1000 Lux.Sec.

Examples 14 to 24 In Example 13, the characteristics of the photoconductor were examined by changing the additives of various amines shown in Table 4 below. The results are summarized in Table 4.

Example 25 Magnesium phthalocyanine compound treated in Example 1
A mixture of 30 g, 10 g of phenoxy resin (PKHH) and 900 g of toluene / ethyl cellosolve / dioxane (4: 4: 1) is dispersed for 2 hours using a paint shaker. The paint made in this way is 0.1μm on the aluminum vapor-deposited PET film.
A charge generation layer having a film thickness of On top of this, 5 parts of p-diethylaminobenzaldehyde-diphenylhydrazone, polycarbonate resin (trade name "Banlite L-1250W")
A solution in which 5 parts of methylene chloride was dissolved in 65 parts of methylene chloride was applied and dried using a wire bar to form a charge transport layer having a thickness of 10 μm to obtain a laminated photoreceptor. The sensitivity of the thus prepared photoconductor was measured according to Example 1 by performing corona discharge at an applied voltage of -6 kV and found to be E _1/2 = 0.6 Lux.Sec.

[Brief description of drawings]

FIG. 1 is a diagram showing an X-ray diffraction spectrum of magnesium phthalocyanine. FIG. 2 shows an absorption spectrum (b) of a dispersion of magnesium phthalocyanine before recrystallization using a compound represented by the general formula (I) in a polyester resin and a compound represented by the general formula (I). It is a figure which shows the absorption spectrum (a) of what disperse | distributed magnesium phthalocyanine after the recrystallization process to the same polyester resin. 3 to 6 are enlarged partial sectional views of the electrophotographic photosensitive member according to the present invention. FIG. 7 is a graph showing the spectral sensitivity of the electrophotographic photoconductor of Example 1. FIG. 8 shows X of magnesium phthalocyanine of Comparative Example 2.
It is a line diffraction diagram. 1 ... Conductive support, 2a, 2b, 2c, 2d ... Photosensitive layer, 3 ...
Magnesium phthalocyanine compound and its derivatives, 4
…… Binder, 5 …… Charge transport medium, 6 …… Charge carrier generation layer, 7 …… Charge transport layer.

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Claims (1)

[Claims] 1. In an X-ray diffraction pattern, 18 °, 20 °, 21 °, 23
An electrophotographic photoreceptor having a photosensitive layer formed by dispersing a magnesium phthalocyanine compound or a derivative thereof having a strong peak at a Bragg angle 2θ of 31 ° and 31 ° in a binder.