JPH0822976B2 - Metal phthalocyanine having a novel crystal structure and photosemiconductor material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical semiconductor material having a specific crystal type and using a mixed crystal of oxytitanium phthalocyanine and oxyvanadium phthalocyanine.

(Prior Art) Phthalocyanines have been actively studied as excellent optical semiconductor materials. Electrophotographic photoconductors, electrophotographic plate-making materials, solar cells, photoelectric conversion materials such as image sensors, optical memory materials such as optical disks and photochromism, photo hole burning (PHB) sensitizers, gas sensors that utilize semiconductor characteristics, Research on organic diode materials is becoming active. In particular, phthalocyanine, which has high sensitivity up to a long wavelength region, is being actively researched and developed as a charge generating material for electrophotographic photoreceptors for semiconductor lasers and electrophotographic photoreceptors for light emitting diodes.

Phthalocyanines not only have different absorption spectra and physical properties such as photoconductivity depending on the type of central metal, but also have significantly different physical properties depending on the crystal type. For example, copper phthalocyanine is known to have large differences in electrophotographic electrical characteristics such as charging property, dark decay, and sensitivity due to differences in crystal types such as α, β, γ, and ε types [Sawada
Gaku: "Dyes and Drugs", Vol. 24, No. 6, p122 (1979)].
In addition, in the case of the electrophotographic photoreceptor, some examples in which a specific crystal type is selected have been reported. Photoreceptors using metal-free phthalocyanines (see, for example, JP-A-60-8655)
1), a photoreceptor using aluminum-containing phthalocyanine (for example, JP-A-63-133462), and many other center metals such as titanium (for example, JP-A-59-49544), indium and gallium. It is known and most choose a particular crystal form.

(Problems to be Solved by the Invention) However, determining the central metal and the crystal type is not sufficient for practical application. For example,
When the above-mentioned phthalocyanine is used as a charge generating agent in a photoreceptor for electrophotography, it is necessary to satisfy not only the sensitivity but also many required performances. Regarding the electrical characteristics, as initial characteristics, not only high sensitivity to a semiconductor laser but also fast response, good charging characteristics, low dark decay, and low residual potential are required. It is required that the characteristics do not change significantly with repeated use, that is, excellent durability.

Methods conventionally used for the purpose of improving these various properties include chemical modification of phthalocyanine molecules, acid treatment, organic solvent treatment, mechanical strain by a ball mill, crystallinity by heat treatment, and the like. Various studies have been conducted, such as controlling the particle size and particle shape, adding an electron-donating substance or an electron-withdrawing substance, and selecting the polarity of the resin used when dispersing in a resin binder. However, in these methods, there are few that satisfy the required various properties in a well-balanced manner, and in many cases, in the resin-dispersed charge generation layer, the dispersibility of the phthalocyanine pigment is significantly impaired, and in practice, the expected effect is obtained. Is often not obtained.

It has been found that the mechanism of photoelectric conversion in phthalocyanines is influenced not by a phenomenon within a single molecule in a crystal but by an interaction between adjacent molecules weakly bound by intermolecular force (for example, N. Minami et al. Japanese Jounal of Applied
Physics Vol.26, No.10, 1987, p.1754). Therefore,
If a mixed crystal is possible in a phthalocyanine molecule having a different metal, the above-mentioned intermolecular force can be artificially controlled, so that a new type of phthalocyanine crystal is created.

Regarding the respective crystal structures of oxytitanium phthalocyanine and oxyvanadium phthalocyanine,
For example, W. Hiller et al. Zeitschrift fur Kristallogra
Although it has been reported in phic, 159, p173, the possibility of mixed crystals is not suggested at all.

As a result of intensive studies to obtain a phthalocyanine having a higher-performance novel structure, the present inventors have found that in a phthalocyanine crystal that is one of molecular crystals, a mixed crystal is formed between phthalocyanine molecules having titanium and vanadium as central metals. Is generated, and
As a charge generating agent for a photoconductor for electrophotography, which is one application as an optical semiconductor material, the inventors have found that the above-mentioned various properties are well-balanced and completed the present invention.

(Means for Solving the Problems) An object of the present invention is to provide a novel type of phthalocyanine crystal that has never existed before, an optical semiconductor material using the same, and photosensitivity in a wide wavelength range (in particular, an oscillation wavelength range of a semiconductor laser). It is to provide a charge generating agent that satisfies excellent initial electrical characteristics such as the photosensitivity near 800 nm) and durability during long-term repeated use.

That is, the present invention is based on the X-ray diffraction spectrum
Bragg angle (2θ ± 0.2 °) 9.2 °, 13.1 °, 20.7 °, 2
Strong diffraction peaks at 6.2 ° and 27.1 ° (hereinafter referred to as β type)
The first component is oxytitanium phthalocyanine,
The second component is composed of oxyvanadium phthalocyanine and has a molar fraction of oxytitanium phthalocyanine of 100.
% In the range of more than 80% and a mixed crystal of phthalocyanine, and X-ray diffraction spectrum, Bragg angles (2θ ± 0.2 °) 7.6 °, 10.2 °, 12.6 °, 22.5
Phthalocyanine crystals showing strong diffraction peaks (hereinafter referred to as α type) at °, 24.3 ° and 28.6 °, the first component being oxytitanium phthalocyanine, the second component being a mixed crystal composed of oxyvanadium phthalocyanine, and β type Alternatively, it exists in an optical semiconductor material containing the α-type compound.

 Hereinafter, the present invention will be described in detail.

The oxytitanium phthalocyanine-oxyvanadium phthalocyanine mixed crystal in the present invention is preferably produced by using, as a starting material, a single phthalocyanine crystal or an amorphous substance, but is not necessarily limited thereto.

The method of synthesizing oxytitanium phthalocyanine as a starting material used herein is described by Moser and Thomas in "Phthalocyanine Compounds" (Moser and Thomas "Ph
thalocianine compounds "), etc., for example, a method of heating and melting O-phthalonitrile and titanium tetrachloride or heating in the presence of an organic solvent such as α-chloronaphthalene, O-phthalonitrile and tetrachloride. It can be obtained in good yield by reaction of titanium chloride with a pyridinium salt or oxidation of chlorotitanium phthalocyanine.In addition, the synthetic product is acid, alkali, or a soluble solvent of the phthalocyanine, for example, methanol, toluene, xylene, chloroform, dichloroethane, It can be obtained by washing with trichloroethane, α-chloronaphthalene, etc. and washing with water, and can be further subjected to sublimation purification or acid paste treatment.

The method for synthesizing oxyvanadium phthalocyanine used as a starting material may be any of the known methods in the above-mentioned documents. For example, a good yield can be obtained by heating and melting O-phthalonitrile and vanadium pentoxide in the presence of an organic solvent, or heating phthalic anhydride with urea and titanium trichloride in the presence of an organic solvent and heating. can get. In addition, the synthetic
Alternatively, it can be obtained by washing with a soluble solvent of the phthalocyanine, for example, methanol, toluene, xylene, chloroform, dichloroethane, trichloroethane, α-chloronaphthalene, or washing with water. Further, sublimation purification and acid paste treatment can also be performed.

The mixed phase is formed by the vapor phase method described below. In general, for the formation of mixed crystals of inorganic substances, in addition to the vapor phase method, a liquid phase method of producing from a molten state, a method of recrystallizing from a solution state of an organic solvent, etc. are known. Is not limited to the vapor phase method. However, the liquid phase method has problems such as thermal decomposition and sublimation of phthalocyanine, and the recrystallization method has problems such as solubility of phthalocyanine. In the case of phthalocyanine rich in sublimation, the gas phase method is most suitable. is there.

A powder of oxytitanium phthalocyanine and oxyvanadium phthalocyanine obtained by the above-mentioned method as a starting material is charged into a sublimation source of a sublimation apparatus by a carrier gas method at a predetermined ratio and heated. Sublimation source temperature is 500 ℃
To 600 ° C., and the adhesion temperature is preferably 480 ° C. or lower.
As the carrier gas, an inert gas such as argon or nitrogen gas is preferable. The pressure is preferably 10 Torr to 0.1 Torr, but so-called simple sublimation without using a carrier gas is also possible.

Thus, the mixed crystal having the β-type or α-type crystal form of the present invention can be obtained.

The material of the present invention is used not only as a copying machine, a semiconductor laser printer, an LED printer, a liquid crystal shutter printer, etc. as an electrophotographic photoreceptor, but also as a photoelectric conversion element such as a solar cell and an image sensor, and further a memory material such as an optical disk. Is also suitable.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples.
The present invention is not limited to the following examples.

Production Example 1 (Production of Starting Material) First, an example of production of oxytitanium phthalocyanine as a starting material will be described.

O-diphthalonitrile 64.0g, titanium tetrachloride 24.3g α
-After reacting in 500 ml of chloronaphthalene at 230 ° C for 3 hours,
It was washed with α-chloronaphthalene, methanol and hot water in this order. Then, it was washed with xylene and dried to obtain 46.0 g of oxytitanium phthalocyanine. 5 of this product
g, was charged into the sublimation source part of the carrier gas method sublimation device, and sublimation was carried out for 1 hour at a temperature of the sublimation source part of 540 ° C., an argon gas flow rate of 70 ml / min, and a pressure of 0.3 Torr. 3.6 g of the deposit in the temperature range of 480 to 350 ° C. was scraped off to obtain a starting material.

Next, an example of producing oxyvanadium phthalocyanine as a starting material is shown. 5 g of oxyvanadium phthalocyanine (reagent manufactured by Kanto Kagaku) was charged into the sublimation source part of the carrier gas sublimation device, and the temperature of the sublimation source part was 540 ° C, the flow rate of argon gas was 70 ml / min, and the pressure was 0.3 Torr. did. 3.5 g of the deposit in the temperature range of 480 to 350 ° C. was scraped off to obtain a starting material.

The powder X-ray diffraction spectra of oxytitanium phthalocyanine and oxyvanadium phthalocyanine thus obtained are shown in FIGS. 1 (a) and (b), respectively.
Shown in Further, the transmission absorption spectra obtained by the method described below are summarized in (a) and (b) of FIG. 2, respectively, and the results of elemental analysis and metal quantitative analysis are summarized in Table 2. Oxytitanium phthalocyanine has a Bragg angle of 9.2 °, 13.1
There are strong diffraction peaks at °, 20.7 °, 26.2 ° and 27.1 ° β
Oxyvanadium phthalocyanine was α-type with strong diffraction peaks at Bragg angles of 7.6 °, 10.2 °, 12.6 °, 22.5 °, 24.3 ° and 28.6 °.

Example 1 The powders of oxytitanium phthalocyanine and oxyvanadium phthalocyanine obtained in Production Example 1 were each mixed with 3.6
g and 0.4 g were mixed and charged into a sublimation source section of a carrier gas sublimation apparatus, and sublimation was performed for 1 hour at a temperature of the sublimation source section of 540 ° C., an argon gas flow rate of 70 ml / min, and a pressure of 0.3 Torr. 480
The deposit in the temperature range of ˜350 ° C. was scraped off to obtain 3.7 g of the product. The powder X-ray diffraction spectrum of this product is shown in FIG. Bragg angle (2θ ± 0.2 °) 9.2 °, 13.1
Shows strong diffraction peaks at °, 20.7 °, 26.2 °, and 27.1 °,
The same diffraction peak as that of the β-type oxytitanium phthalocyanine crystal was observed. At the same time, the Bragg angle (2θ ± 0.2
(°) 7.6 °, 10.2 °, 12.6 °, 22.5 °, 24.3 °, 28.6 ° showed strong diffraction peaks, and the diffraction peaks which characterize the α-type oxytitanium phthalocyanine described later were observed, though a few. That is, β-type and α-type are mixed as the crystal type.

Next, in order to confirm that the product obtained by sublimation was not a simple mixture of oxytitanium phthalocyanine and oxyvanadium phthalocyanine, an infrared absorption spectrum was measured. The measurement was performed using a JEOL FTIR (JIR-100) by the nucleic acid reflection method at a resolution of 0.5 cm ^-1 . Sixth
In the figure, (b) shows an infrared absorption spectrum of wave numbers 900 to 1020 cm ^-1 . Table 1 summarizes the attribution and peak position of each absorption.
It is not observed in the powder mixture of oxytitanium phthalocyanine and oxyvanadium phthalocyanine of Comparative Example 1 described later. A new peak (indicated by B in the figure) near 994 cm ^-1 has appeared, indicating that a new molecular vibration mode has been induced with the change in intermolecular force due to the formation of mixed crystals. ing.

Next, Table 2 shows the metal quantitative analysis results and the elemental analysis results of oxytitanium phthalocyanine and oxyvanadium phthalocyanine of this mixed crystal.

Further, in order to measure the absorption spectrum, a dispersion liquid of phthalocyanine was prepared by the method of Application Example 1 described later, and was applied onto a cover glass and dried to form a pigment dispersion layer. The transmission absorption spectrum is shown in FIG.

Comparative Example 1 The results of infrared absorption spectrum of a mixture of β-type oxytitanium phthalocyanine and α-type oxyvanadium phthalocyanine in a powder form at a weight ratio of 90:10 are shown in FIG. 6 (a) and Table 1.

The β-type oxytitanium phthalocyanine used here was obtained by sublimating 4.0 g of oxytitanium phthalocyanine obtained in Production Example 1 again under the same conditions as in Example 1.

The α-type oxyvanadium phthalocyanine used here was obtained by sublimating 4.0 g of oxyvanadium phthalocyanine obtained in Production Example 1 again under the same conditions as in Example 1.

Example 2 3.2 parts each of powders of oxytitanium phthalocyanine and oxyvanadium phthalocyanine obtained in Production Example 1 were prepared.
g and 0.8 g were mixed and charged into a sublimation source section of a carrier gas sublimation apparatus, and sublimation was carried out in the same manner as in Example 1. 480-350
The deposit in the temperature range of ° C was scraped off to obtain 3.7 g of a product. The powder X-ray diffraction spectrum of this product is shown in FIG. 3 (b). Bragg angle (2θ ± 0.2 °) 7.6 °, 10.2
It showed strong diffraction peaks at °, 12.6 °, 22.5 °, 24.3 ° and 28.6 °, showing the same diffraction peak as α-type oxytitanium phthalocyanine. However, unlike Example 1, no diffraction peak derived from β type was observed.

Next, the infrared absorption spectrum was measured in the same manner as in Example 1. The results are shown in FIG. 6 (d) and Table 1. Comparative Example 2 described below
Of, 1003 cm ^-1 vicinity of peaks observed in the powder mixture of oxytitanium phthalocyanine and oxyvanadium phthalocyanine (shown in the figure A) is, that has shifted about 2 cm ^-1 to a lower wavenumber side was observed. Such a phenomenon is usually observed in the mixed crystal system of inorganic substances, and it has become one of the means for identifying the mixed crystal. The subtle changes in intermolecular force due to the formation of mixed crystals are the result of changes in the molecular vibrational energy, indicating that mixed crystals are formed in this system.

Next, Table 2 shows the metal quantitative analysis results of oxytitanium phthalocyanine and oxyvanadium phthalocyanine of this mixed crystal.

 FIG. 5 (b) shows the transmission absorption spectrum.

Comparative Example 2 The results of infrared absorption spectrum of a mixture of α-type oxytitanium phthalocyanine and α-type oxyvanadium phthalocyanine in powder form at a weight ratio of 80:20 are shown in FIG. 6 (c) and Table 1.

The α-type oxytitanium phthalocyanine used here was the same as in Example 1 except that 4.0 g of the oxytitanium phthalocyanine obtained in Production Example 1 was set to the adhesion temperature of 200 ° C.
It was sublimated again under the same conditions as.

Further, the α-type oxyvanadium phthalocyanine used here is the one obtained in Comparative Example 1.

Examples 3-5 3.8 g, 0.2 g (Example 3) 2.4 g, 1.6 g (Example 4) 0.8 g, 3.2 g (implementation) of the powders of oxytitanium phthalocyanine and oxyvanadium phthalocyanine obtained in Production Example 1, respectively. Example 5) The components were mixed and charged into a sublimation source section of a carrier gas sublimation apparatus, and sublimation was performed in the same manner as in Example 1. Powder X-ray diffraction spectra obtained by the same method as in Example 1 are shown in FIGS. 4 (c), (d) and (e), an infrared absorption spectrum is shown in Table 1, and a transmission absorption spectrum is shown in FIG. (C),
The results of quantitative metal analysis and elemental analysis are shown in (d) and (e), respectively.

In Example 3, similarly to Example 1, in the crystal form, a diffraction peak derived from β type was strongly observed, and an α type peak was also observed although the diffraction intensity was weak. In the infrared absorption spectrum, the peak around 994 cm ^-1 (B in the figure) was obtained as in Example 1.
(Indicated by) newly appeared.

In Examples 4 and 5, only the diffraction peak derived from α type was observed in the crystal form as in Example 2. In the infrared absorption spectrum, as in Example 2, it was observed that the peak near 1003 cm ^-1 (indicated by A in the figure) was shifted to the lower wave number side.

 Both show that mixed crystals are generated.

Application Examples 1 and 2 (Preparation of Electrophotographic Photoreceptor) 1 g of the mixed crystal obtained in Example 1 was added to 33 g of 4-methoxy-4-methyl-2-pentanone and 0.5 g of butyral resin (BM-2 manufactured by Sekisui Chemical Co., Ltd.). Was added to the melted solution and dispersed for 6 hours with a paint shaker. This dispersion was coated on aluminum with a 0.1 μm thick polyamide (Toray, CM4
001) undercoat layer and apply at 100 ℃ for 1
It was dried for an hour to form a 0.1 μm charge generation layer. Next, a liquid prepared by dissolving 50 parts by weight of P-diethylaminobenzaldehyde (diphenylhydrazone) as a charge transfer agent and 50 parts by weight of a polycarbonate resin (PCZ manufactured by Mitsubishi Gas Chemical Co., Inc.) in 100 parts by weight of 1,2-dichloroethane was placed on the charge generation layer. A 17 μm-thick charge transfer layer was formed by coating and drying to obtain a photoconductor for electrophotography (Application Example 1). In the same manner, a photoconductor was prepared by using the mixed crystal crystal obtained in Example 2 (Application Example 2).
The characteristics of these photoconductors were measured by the following methods.

Kawaguchi Electric Co., Ltd. electrostatic copying paper tester model EPA-8100
At −6kVk, charged in a dark place for 1 second, and then monochromated with an interference filter at wavelengths of 800nm and 6
The surface potential was measured by exposing 50 nm to 4.2 μW / cm ^{2 for} 2 seconds.
Initial charge position (Vo), half exposure sensitivity (E _1/2 ), exposure amount 5
The surface potential (Vi), residual potential (Vr), dark decay (DD) and repeatability at μJ / cm ² were determined. The results are shown in Table 3, and Table 4 shows the characteristics after 10,000 charging / exposure cycles.

Vo, E _1/2 , Vi, Vr, and DD all show very good electrophotographic characteristics, and the repeating characteristics are also satisfactory.

(Effects of the Invention) As described above, the phthalocyanine mixed crystal of the present invention has an excellent photoelectric conversion ability from the semiconductor laser oscillation wavelength range to the light emitting diode emission range.

[Brief description of drawings]

FIG. 1 shows a powder X-ray diffraction spectrum of phthalocyanine as a starting material obtained in Production Example 1, FIG. 2 shows a transmission absorption spectrum of a dispersion layer obtained from the same phthalocyanine, and (a) shows oxytitanium phthalocyanine. (B)
Is oxyvanadium phthalocyanine. 3 and 4 show powder X-ray diffraction spectra of phthalocyanines of Examples, FIG. 5 shows transmission absorption spectra of dispersion layers obtained from the same phthalocyanines, (a) shows Example 1,
(B) is Example 2, (c) is Example 3, (d) is Example 4, and (e) is Example 5. FIG. 6 shows infrared absorption spectra of phthalocyanines of Examples and Comparative Examples, (a) is Comparative Example 1, (b) is Example 1,
(C) is for Comparative Example 2, and (d) is for Example 2.

Claims (3)

[Claims] 1. In X-ray diffraction spectrum, Bragg angles (2θ ± 0.2 °) 9.2 °, 13.1 °, 20.7 °, 26.2 °, 27.1
Shows a strong diffraction peak at ゜, the first component is oxytitanium phthalocyanine, the second component is oxyvanadium phthalocyanine, and the molar fraction of oxytitanium phthalocyanine is less than 100% and more than 80%. Phthalocyanine crystal. 2. In X-ray diffraction spectrum, Bragg angle (2θ ± 0.2 °) 7.6 °, 10.2 °, 12.6 °, 22.5 °, 24.3
A phthalocyanine crystal that shows a strong diffraction peak at 2 ° and 28.6 °, and is a mixed crystal composed of oxytitanium phthalocyanine as the first component and oxyvanadium phthalocyanine as the second component. 3. In X-ray diffraction spectrum, Bragg angles (2θ ± 0.2 °) 9.2 °, 13.1 °, 20.7 °, 26.2 °, 27.1
Shows a strong diffraction peak at ゜, the first component is oxytitanium phthalocyanine, the second component is oxyvanadium phthalocyanine, and the molar fraction of oxytitanium phthalocyanine is less than 100% and more than 80%. In the phthalocyanine crystal or X-ray diffraction spectrum, Bragg angle (2θ ± 0.2 °) 7.6 °, 1
It shows strong diffraction peaks at 0.2 °, 12.6 °, 22.5 °, 24.3 ° and 28.6 °, and at least one of phthalocyanine crystals composed of a mixed crystal composed of oxytitanium phthalocyanine as the first component and oxyvanadium phthalocyanine as the second component. An optical semiconductor material containing a seed.