JP3196260B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor using oxytitanium phthalocyanine of a specific crystal type as a charge generating agent.

[0002]

2. Description of the Related Art Hitherto, phthalocyanines and metal phthalocyanines have shown good photoconductivity and have been used, for example, in electrophotographic photosensitive members. In recent years, laser beam printers, which use laser light as a light source instead of conventional white light, and have the advantages of high speed, high image quality, and low impact, have become widespread. Research is being actively conducted. In particular, various methods using a semiconductor laser as a light source, which has been remarkably advanced in recent years, have been attempted among laser light. In this case, since the wavelength of the light source is approximately 800 nm, a characteristic having high sensitivity to long wavelength light of approximately 800 nm is used. Is strongly desired. Known organic photoconductive materials satisfying this requirement include methine squaric acid dyes, cyanine dyes, pyrylium dyes, thiapyrylium dyes, polyazo dyes, and phthalocyanine dyes. Of these,
Methine squaric acid-based, cyanine-based dyes, pyrylium-based dyes, and thiapyrylium-based dyes are relatively easy to increase spectral sensitivity, but lack practical stability such as repeated use, and polyazo-based dyes It is difficult to increase the absorption wavelength and there is a problem in manufacturing. On the other hand, phthalocyanine dyes can be synthesized relatively easily,
Vigorous research due to the fact that it has an absorption peak in the long wavelength region of at least nm and that the spectral sensitivity changes depending on the central metal and crystal type, and that several semiconductor lasers exhibit high sensitivity in the wavelength region. Development is taking place.

[0003] Phthalocyanines not only have different absorption spectra and photoconductivity depending on the type of central metal, but also have different physical properties depending on the crystal type. Some examples have been reported in which is selected as an electrophotographic photosensitive member. For example, it is reported that oxytitanium phthalocyanine has various crystal forms, and there is a great difference in chargeability, dark decay, sensitivity, and the like due to the difference in the crystal forms. JP 59
In JP-A-49544, the crystal form of oxytitanium phthalocyanine has a Bragg angle (2θ ± 0.2 °).
= 9.2 °, 13.1 °, 20.7 °, 26.2 °, 2
Those which give a strong diffraction peak at 7.1 ° are described as being suitable, and an X-ray diffraction spectrum is shown. In JP-A-59-166959, a vapor-deposited film of oxytitanium phthalocyanine is left in saturated vapor of tetrahydrofuran for 1 to 24 hours to change the crystal form to form a charge generation layer. The X-ray diffraction spectrum is
The number of peaks is small and wide, and the Bragg angle (2
θ) = 7.5 °, 12.6 °, 13.0 °, 25.4
°, 26.2 ° and 28.6 ° show strong diffraction peaks.

[Problems to be solved by the invention]

However, in a system using such a photoconductive material for an electrophotographic photosensitive member, sensitivity has a large temperature dependency, and a sufficiently satisfactory performance as an electrophotographic photosensitive member has not been obtained. Further, since the sensitivity of the photoreceptor is uniquely determined, the construction of an image forming process for obtaining a high-quality image is restricted. Furthermore, the sensitivity of these photoconductors is insufficient for the recent increase in speed of laser printers, making it difficult to increase the speed of laser printers.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photoreceptor having a high sensitivity and a small temperature dependency of the sensitivity. Another object of the present invention is to provide an image forming process using a step of forming an electrostatic latent image by spot exposure with an exposure beam in an image forming process and a process of developing the electrostatic latent image with a developer. An object of the present invention is to provide an electrophotographic photosensitive member capable of adjusting the sensitivity of the photosensitive member to the light amount of the exposure beam used here so that the image quality is sharp.

[0006]

The present invention has been made to achieve the above object of the present invention, and its gist is that at least the black angle (2θ) in the X-ray diffraction spectrum is determined.
± 0.2 °) 9.3 °, 10.6 °, 13.2 °, 1
5.1 °, 15.7 °, 16.1 °, 20.8 °, 2
Oxytitanium phthalocyanine having a crystal form which shows clear diffraction peaks at 3.3 °, 26.3 ° and 27.1 °, and gives the maximum diffraction peak at a black angle of 26.3 °, and a black angle (2θ Oxytitanium phthalocyanine having a crystal form giving the maximum diffraction peak at 27.3 °) in the photosensitive layer.

Hereinafter, the present invention will be described in detail. The oxytitanium phthalocyanine used in the present invention includes, for example, the following general formula (I)

[0008]

Wherein X represents a halogen atom, and n represents 0
Represents a number from to 1. ). In the general formula (I), X is a chlorine atom and n is 0.
To 0.5 are preferred. The oxytitanium phthalocyanine used in the present invention can be easily synthesized from, for example, 1,2 dicyanobenzene (orthophthalonitrile) and a titanium compound according to the following reaction formula (1) or (2).

[0010]

That is, 1,2-dicyanobenzene and a halide of titanium are reacted by heating in an inert solvent. As the titanium compound, titanium tetrachloride, titanium trichloride, titanium tetrabromide and the like can be used. As an inert solvent, trichlorobenzene, α-chloronaphthalene,
β-chloronaphthalene, α-methylnaphthalene, methoxynaphthalene, diphenyl ether, diphenylmethane, diphenylethane, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether,
High-boiling organic solvents inert to the reaction, such as triethylene glycol dialkyl ether, are preferred. The reaction temperature is usually 1
50-300 ° C, particularly preferably 180-250 ° C. The dichlorotitanium phthalocyanine formed after the reaction is filtered off and washed with the solvent used in the reaction to remove impurities generated during the reaction and unreacted raw materials.

Next, alcohols such as methanol, ethanol and isopropyl alcohol, tetrahydrofuran,
The solvent used in the reaction is removed by washing with an inert solvent such as ethers such as diethyl ether. Next, the obtained dichlorotitanium phthalocyanine is hydrolyzed into oxytitanium phthalocyanine.

Then, the obtained oxytitanium phthalocyanine is subjected to, for example, a hot water treatment disclosed in JP-A-62-67094 or a mechanical grinding treatment disclosed in JP-A-2-215866. Thus, a desired crystal form can be obtained. Further, the crystalline oxytitanium phthalocyanine used in the present invention is not limited to only the crystalline oxytitanium phthalocyanine produced by the above-mentioned production method, and for example, is also suitable from other crystalline oxytitanium phthalocyanines. Oxytitanium phthalocyanine, which can be produced by any of the above methods,
In the line diffraction spectrum, at least black angle (2θ ± 0.2 °) 9.3 °, 10.6 °, 13.2
°, 15.1 °, 15.7 °, 16.1 °, 20.8
°, 23.3 °, 26.3 °, and 27.1 ° show clear diffraction peaks, of which a crystal form giving the largest diffraction peak at a black angle of 26.3 ° is shown. FIG. 1 shows X-ray diffraction. Includes as long as they belong to the same crystal form as the crystal form showing the spectrum (hereinafter referred to as phthalocyanine 1). In the X-ray diffraction spectrum, the black angle (2θ ± 0.
2 °) indicates a crystal form that gives the maximum diffraction peak at 27.3 °, and is included as long as it belongs to the same crystal form as the crystal form whose X-ray diffraction spectrum is shown in FIG. 2. , Usually other than 27.3 °, around 9.5 °.
It shows a relatively clear diffraction peak even at 1 °. Hereinafter, it is referred to as phthalocyanine 2.)

These oxytitanium phthalocyanines having different crystal forms are mixed and dispersed in a dispersion medium, and finally prepared as a coating solution for coating a photosensitive layer in a state of being mixed with a binder resin, Alternatively, the oxytitanium phthalocyanine of each crystal type is subjected to a dispersion treatment in a dispersion medium, and further adjusted to a state of being mixed with a binder resin, and the adjusted liquids are mixed to apply a photosensitive layer. Liquid. Various solvents may be used as the dispersion medium. For example, ethers such as diethyl ether, dimethoxymethane, tetrahydrofuran and 1,2-dimethoxyethane; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; alcohols such as methanol, ethanol and propanol alone. Alternatively, two or more kinds can be used as a mixture.

As the binder resin, polyvinyl butyral,
Polyvinyl acetal, polyester, polycarbonate, polystyrene, polyester carbonate, polysulfone, polyimide, polymethyl methacrylate, vinyl polymers such as polyvinyl chloride, and copolymers thereof, phenoxy, epoxy, silicone resin, etc., or partially cross-linked cured products thereof Etc. can be used alone or in combination of two or more. As a method for dispersing the oxytitanium phthalocyanine, a known method such as a ball mill, a sand grind mill, a planetary mill, a roll mill, or the like can be used.

Examples of the method of mixing the binder resin with the oxytitanium phthalocyanine particles include a method of dispersing the oxytitanium phthalocyanine particles at the same time as the binder resin in the form of a powder or a polymer solution thereof and simultaneously dispersing the dispersion. Any method may be used, such as a method of mixing the polymer solution in the polymer solution of the landing resin, or a method of mixing the polymer solution in the dispersion liquid. The content ratio of phthalocyanine 1 to phthalocyanine 2 is such that phthalocyanine 1 is 1 part by weight and phthalocyanine 2 is 0.1 part by weight.
It is used in the range of 1 to 10 parts by weight. Each crystal form of oxytitanium phthalocyanine is subjected to dispersion treatment in a dispersion medium, and further adjusted to a state of being mixed with a binder resin, and the adjusted liquids are mixed to form a coating liquid for coating the photosensitive layer. The method of mixing the liquids prepared in each case is, for example, mixing using a mechanical stirrer, a homomixer, a homogenizer, or mixing by applying ultrasonic waves, and any other known method may be used. .

Next, the dispersion obtained here may be diluted with various solvents in order to obtain liquid properties suitable for coating. As the solvent, for example, the solvents exemplified as the dispersion medium can be used. The ratio of oxytitanium phthalocyanine to the binder resin is not particularly limited, but generally oxytitanium phthalocyanine is used in an amount of 5 to 500 parts by weight per 100 parts by weight of the resin. In this dispersion, the concentration of oxytitanium phthalocyanine is preferably used in the range of 0.1% by weight to 10% by weight. Further, a charge transfer agent can be included as needed. Examples of the charge transfer agent include electron-withdrawing substances such as 2,4,7-trinitrofluorenone and tetracyanoquinodimethane, and heterocyclic rings such as carbazole, indole, imidazole, oxazole, pyrazoline, oxadiazole, pyrazoline, and thiazole. Compounds, aniline derivatives, hydrazone compounds,
An electron donating substance such as an aromatic amine derivative, a stilbene derivative, or a polymer having a group consisting of these compounds in a main chain or a side chain is exemplified. The ratio of the charge transfer agent to the binder resin is in the range of 5 to 500 parts by weight based on 100 parts by weight of the binder resin.

Using the dispersion thus prepared,
A charge generation layer is formed on a conductive support, and a charge transfer layer is laminated thereon to form a photosensitive layer, or a charge transfer layer is formed on a conductive support, and the dispersion liquid is formed thereon. To form a photosensitive layer by using the dispersion to form a photosensitive layer on the conductive support. be able to. When the photosensitive layer is formed by laminating the charge generation layer and the charge transfer layer, the thickness of the charge transfer layer is preferably 0.1 μm to 10 μm, and the thickness of the charge transfer layer is preferably 5 μm to 60 μm. When the photosensitive layer is formed with a single structure including only the charge generation layer, the thickness of the charge generation layer is preferably in the range of 5 μm to 60 μm.

When a charge transfer layer is provided, as the charge transfer agent used therein, the materials exemplified as the charge transfer agent can be used. A binder resin is blended with these charge transfer agents as needed. As the binder resin, for example, the binder resins exemplified as the binder resin can be used. The photosensitive layer may contain various additives such as an antioxidant and a sensitizer as needed. The photosensitive layer is provided on a conductive support. Examples of the conductive support include a metal material such as aluminum, stainless steel, and nickel, and a conductive layer such as aluminum, copper, palladium, tin oxide, and indium oxide on the surface. An insulating support such as a polyester film, paper, or glass provided with is used.
A well-known barrier layer, which is generally used, may be provided between the conductive support and the photosensitive layer.

Examples of the barrier layer include an anodized aluminum film, an inorganic layer such as aluminum oxide and aluminum hydroxide, polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, And the like. The thickness of the barrier layer is 0.
1 μm to 20 μm, preferably 0.1 μm to 10 μm
It is most effective to use in the range of m.

[0021]

According to the present invention, an exposure amount used in an image forming process using a step of forming an electrostatic latent image by spot exposure with an exposure beam, and a step of developing the electrostatic latent image with a developer. Therefore, the sensitivity of the photoconductor can be adjusted to the sensitivity required for maintaining sharpness of image quality, and the environmental characteristics of electrical characteristics are improved.

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Production Examples, but is not limited thereto.

Production Example 1 97.5 g of phthalodinitrile was converted to α-chloronaphthalene 7
50 ml of titanium tetrachloride 2 under a nitrogen atmosphere.
2 ml are added dropwise. After dropping, raise the temperature, and stir for 20 minutes.
After reacting at 0 to 220 ° C. for 3 hours, the mixture is allowed to cool,
The mixture was filtered while hot at 130 ° C., and washed with 200 ml of α-chloronaphthalene heated to 100 ° C. 200ml of N
-Hot suspension washing with methylpyrrolidone (100 ° C, 1 hour)
Was performed three times. Then, the suspension was washed with 300 ml of methanol at room temperature, and further washed with 500 ml of methanol for 1 hour.
I went there. The X-ray diffraction spectrum of the oxytitanium phthalocyanine thus obtained is shown in FIG. As is clear from FIG. 1, the black angle (2θ ± 0.2 °) is 4 °.
There is no substantial peak from ° to 8 °, 9.3 °, 1
0.6 °, 13.2 °, 15.1 °, 15.7 °, 1
6.1 °, 20.8 °, 23.3 °, 26.3 °, 2
There is a clear diffraction peak at 7.1 °, of which 26.3.
° peak is the strongest.

Production Example 2 The oxytitanium phthalocyanine obtained in Production Example 1 was ground by a sand grinding mill for 20 hours, followed by 400 ml of water and orthodichlorobenzene 4
The mixture was placed in 0 ml of the suspension and heat-treated at 60 ° C. for 1 hour. FIG. 2 shows an X-ray diffraction spectrum of the oxytitanium phthalocyanine thus obtained. As apparent from FIG. 2, 27. at the black angle (2θ ± 0.2 °).
It can be seen that the maximum is at 3 ° and a sharp peak is shown.

Example 1 6 parts by weight of the oxytitanium phthalocyanine (phthalocyanine 1) prepared in Preparation Example 1 and 4 parts of the oxytitanium phthalocyanine (phthalocyanine 2) prepared in Preparation Example 2
200 parts by weight of n-propanol was added to the parts by weight, and the mixture was pulverized with a sand grind mill for 10 hours, and subjected to atomization dispersion treatment. Next, polyvinyl butyral (Electrical Chemical Industry Co., Ltd.)
Manufactured by Denka Butyral # 6000c) (5 parts by weight of a 10% methanol solution) to prepare a dispersion. Next, a charge generation layer was provided on an aluminum vapor-deposited surface on which the dispersion was vapor-deposited on a polyester film so that the film thickness after drying was 0.4 μm by a bar coater. next,
On this charge generation layer, 56 parts by weight of a hydrazone compound represented by the following chemical formula (1), 14 parts by weight of a hydrazone compound represented by the following chemical formula (2), and 1.5 parts by weight of a cyano compound represented by the following chemical formula (3) Department

[0026]

[0027]

[0028]

A solution prepared by dissolving 100 parts by weight of a polycarbonate resin (NOVAREX 7030A, manufactured by Mitsubishi Kasei Co., Ltd.) in 1,000 parts by weight of 1,4-dioxane is applied by a film applicator. 1
The charge generation layer is provided to have a thickness of 7 μm. The photoreceptor thus obtained is referred to as photoreceptor A.

Example 2 3 parts by weight of the oxytitanium phthalocyanine produced in Production Example 1 and 7 parts by weight of the oxytitanium phthalocyanine produced in Production Example 2 in place of the mixing ratio of the two oxytitanium phthalocyanines used in Example 1 A photoreceptor was prepared in the same manner as in Example 1 except for the above. The photoreceptor thus obtained is referred to as photoreceptor B.

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 1, except that only 10 parts by weight of the oxytitanium phthalocyanine produced in Production Example 1 was used as the oxytitanium phthalocyanine.
The photoreceptor thus obtained is referred to as photoreceptor C.

Comparative Example 2 A photoconductor was prepared in the same manner as in Example 1, except that only 10 parts by weight of the oxytitanium phthalocyanine produced in Production Example 2 was used as the oxytitanium phthalocyanine. The photoreceptor thus obtained is referred to as photoreceptor D.

Evaluation The photoreceptor obtained was evaluated for its half-life exposure sensitivity as an initial electrical characteristic by an electrostatic copying paper tester (model SP, manufactured by Kawaguchi Electric Works, Ltd.).
-428), at 5 ° C, 25 ° C, and 35 ° C. That is, the photoreceptor is negatively charged by corona discharge with an applied voltage set so that the corona current is 22 μA in a dark place, and then continuously exposed to white light having an illuminance of 1.0 lux, and the surface is changed from −450 V to −450 V. The amount of exposure (E1 / 2) required to reduce to 225v was measured. Table 1 shows the results.

[0034]

[Table 1]

From Table 1, it can be seen that the photoconductors A, B and D have high sensitivity, have low temperature dependence of the sensitivity and have good electrical characteristics. It shows that the sensitivity can be controlled by the content ratio of phthalocyanine 1 and phthalocyanine 2. On the other hand, the photoconductor C shows that the sensitivity has a large temperature dependency.

The sharpness of images was evaluated using various commercially available laser printers. Photoconductors A and B obtained good images in all of solid images, line images, and dot patterns. Further, depending on the type of laser printer, the photoconductor A or the photoconductor B was more suitable for obtaining a good image depending on the exposure amount. The photoreceptor C often had no solid image density, and the photoreceptor D often had a thick line image and a crushed dot pattern, resulting in a loss of resolution.

From the above results, the photoreceptor of the present invention is an electrophotographic photoreceptor having a high sensitivity and a small temperature dependency of the sensitivity, and the sensitivity can be controlled. Forming an electrostatic latent image, and developing the electrostatic latent image with a developer. When using the image forming process, the sensitivity of the photoconductor is adjusted so that the image quality is sharp. It is possible to match the light amount of the beam.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction spectrum of oxytanium phthalocyanine obtained in Production Example 1.

FIG. 2 is an X-ray diffraction spectrum of oxytitanium phthalocyanine obtained in Production Example 2.

Continuation of the front page (56) References JP-A-2-183263 (JP, A) JP-A-2-183261 (JP, A) JP-A-2-183262 (JP, A) JP-A-62-272272 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 5/06

Claims (2)

(57) [Claims] In an X-ray diffraction spectrum, at least a black angle (2θ ± 0.2 °) of 9.3 °, 10.6
°, 13.2 °, 15.1 °, 15.7 °, 16.1
°, 20.8 °, 23.3 °, 26.3 °, 27.1 °
Shows a clear diffraction peak, of which the black angle is 26.3.
Oxytitanium phthalocyanine having a crystal form that gives the maximum diffraction peak in ° and black angle (2θ ± 0.2
°) An electrophotographic photoreceptor characterized in that the photosensitive layer contains oxytitanium phthalocyanine having a crystal form giving a maximum diffraction peak at 27.3 °. 2. An oxytitanium cover in a photosensitive layer.
The content ratio of Russiannin is the largest at the black angle of 26.3 °
Oxytitanium Having a Crystal Form That Gives a Diffraction Peak
For 1 part by weight of phthalocyanine, the black angle (2θ
± 0.2 °) which gives the maximum diffraction peak at 27.3 °
Oxytitanium phthalocyanine having a crystal form 0.1
The electrophotographic feeling according to claim 1, wherein the amount is in the range of 10 to 10 parts by weight.
Light body.