JP2001356505A - Method for manufacturing electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce so-called Y-type titanyl oxyphthalocyanine with good reproducibility. SOLUTION: The method for manufacturing an electrophotographic photoreceptor features that when the Y-type titanyl oxyphthalocyanine is dispersed, the temperature of the dispersion liquid is maintained in the range from -10 deg.C to 3 deg.C with fluctuation of the temperature of the dispersion liquid controlled to within 4 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrophotographic photosensitive member using a specific oxytitanium phthalocyanine crystal as a charge generating agent.

[0002]

2. Description of the Related Art In recent years, laser printers which use laser light as an exposure light source in place of conventional white light and have the advantages of high speed, high image quality, high definition and non-impact have become widespread. The development of photoreceptors with high sensitivity and good responsiveness that can withstand odors has been actively pursued.

In order to obtain such a photosensitive member having high sensitivity and good responsiveness, a Bragg angle (2θ ± 0.2 °) 9.
It is effective to use a crystal of oxytitanium phthalocyanine (hereinafter simply referred to as “Y-type TiOPc”) having diffraction peaks at 2 °, 14.3 °, 24.0 °, and 27.3 ° as a charge generating agent. is there. For example, Japanese Unexamined Patent Publication
JP-A-257458 discloses that a crystal form of Y-type TiOPc can be stably produced by a dispersion treatment at 10 ° C. or lower.

[0004]

However, the Y-type T
Since iOPc has a metastable crystal form, a stable (for example, α-type or β-type TiOP
It is easy to change to c). For this reason, Japanese Unexamined Patent Publication No.
No. 8, the temperature of the dispersion is 10 ° C.
When the dispersion treatment is performed as follows, to some extent Y-type TiO
Although Pc can be manufactured stably, a partially stable type of TiOP
There is a problem that c may be generated.

[0005]

Means for Solving the Problems In order to prepare a stable dispersion with good reproducibility while maintaining the crystal type of Y-type TiOPc, the dispersion conditions were examined. The present inventors have found that it is important not only to lower the temperature but also to sufficiently consider the temperature change (ΔT), and have reached the present invention.

That is, the gist of the present invention is to provide a Y-type TiOP
When performing dispersion treatment of c, the dispersion temperature is -3C to 10C,
More preferably, the present invention is directed to a method for producing an electrophotographic photoreceptor in which the temperature is set at −3 ° C. to 3 ° C. and the change in liquid temperature (ΔT) during the dispersion treatment is controlled within 4 ° C., more preferably within 2 ° C. In the case of Y-type TiOPc, when the dispersion treatment is performed in a state where the temperature change is small, the crystal type change to a stable crystal is less likely to occur. For this reason, it is more effective to perform the dispersion treatment without changing the crystal form of the Y-type TiOPc if the temperature change is further reduced, not only at a low temperature.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The electrophotographic photoreceptor of the present invention includes a conductive support and a photosensitive layer formed on the conductive support. The photosensitive layer may be of a so-called stacked type including two layers of a charge generation layer and a charge transfer layer, or may be a single layer type including only one layer. Further, an intermediate layer may be provided between the conductive support and the photosensitive layer. Further, a protective layer may be provided on the surface of the photosensitive layer.

As the conductive support, metal materials such as aluminum, stainless steel, copper, nickel and alloys thereof, and aluminum, copper, palladium, tin oxide,
For example, an insulating support such as a polyester film, paper, or glass prepared by depositing a conductive layer of indium oxide or the like is used. The charge generation layer includes Y-type TiOPc as a charge generation material and a binder resin. The Y-type TiOPc crystal can be produced by a known production method.

In the normal case, Y-type TiOPc is 27.3.
In addition to °, relatively clear diffraction peaks are also shown at around 9.5 °, 14.3 °, and 24.0 °. Due to small differences in the manufacturing conditions, the relative relationship between the peak intensities may slightly fluctuate. Examples of the binder resin include polyvinyl butyral, polyvinyl acetal, polyester, polycarbonate, polystyrene, polyester carbonate, polysulfone, polyimide, polymethyl methacrylate, and vinyl polymers such as polyvinyl chloride, and copolymers thereof, phenoxy, epoxy, and silicone. Resins, etc., or partially crosslinked and cured products thereof can be used alone or in combination of two or more.

The ratio between the Y-type TiOPc and the binder resin is not particularly limited as long as the characteristics as an electrophotographic photosensitive member can be exhibited. Generally, Y type TiOPc is used in a range of 5 to 500 parts by weight based on 100 parts by weight of the resin. Further, the charge generation layer may contain an antioxidant, a sensitizer, a lubricant, and the like, if necessary.

The Y-type TiOPc is subjected to a dispersion treatment,
After mixing with a binder resin or the like to prepare a solution, it is applied on a conductive support. When Y-type TiOPc is subjected to dispersion treatment in a dispersion medium, the temperature of the dispersion is maintained at 10 ° C. to −3 ° C., and the temperature change (ΔT) of the dispersion is within 4 ° C., more preferably the dispersion. The temperature is maintained between 3 ° C. and −3 ° C., and most preferably is cooled such that ΔT is controlled within 2 ° C.

[0012] The dispersion medium used in the above dispersion processing includes:
Various solvents may be used as long as the crystal form of Y-type TiOPc used as a raw material is not changed. Such a dispersion solvent, for example, diethyl ether, dimethoxymethane, tetrahydrofuran, linear such as 1,2-dimethoxyethane, cyclic ethers, acetone, methyl ethyl ketone, linear such as cyclohexanone, cyclic ketones, methyl acetate, methyl acetate, Esters such as ethyl acetate and alcohols such as methanol, ethanol and propanol can be used alone or in combination of two or more.

The amount of the dispersion medium used may be any amount as long as the dispersion can be sufficiently performed and the dispersion contains an effective amount of oxytitanium phthalocyanine. Usually, the concentration of the Y-type TiOPc in the dispersion at the time of dispersion is used. It is preferably about 3 to 20% by weight, more preferably about 4 to 20% by weight.
As a method of performing the dispersion treatment, a known method, for example, a method such as a ball mill, a sand grind mill, and a roll mill can be used. Among these, a method using a sand grind mill is particularly preferable from the viewpoint of dispersion efficiency and the like.

As a method for controlling and cooling the container holding the dispersion solution with a refrigerant at a constant temperature, a known method is used. For example, direct cooling with dry ice, water,
A refrigerant using a cryogen such as ice and salt, a refrigerant using methanol, butanol, glycerin and the like in combination are also effective. In order to control and maintain the temperature of the dispersion liquid at a constant temperature, it is preferable to use a dispersion liquid temperature management device. The dispersion liquid temperature management device includes a dispersion liquid temperature measurement unit that measures the temperature during the dispersion process, and a refrigerant control unit that controls the flow rate of the refrigerant that cools the dispersion liquid holding device based on the obtained temperature data. I do. As the dispersion liquid temperature measuring means, the dispersion processing step is measured at an electronic thermometer or the like inserted into the dispersion liquid, and simultaneously, a signal is sent to the refrigerant flow control device to control the flow rate, so that the dispersion processing step is performed at a constant temperature. The temperature change (ΔT) is also made in a very narrow range.

Next, in order to obtain liquid properties suitable for coating, the dispersion obtained here may be diluted with various solvents unless the crystal form of Y-type TiOPc is changed. Absent. As such a solvent, for example, the solvents exemplified as the dispersion solvent can be used. The method of mixing the binder resin and the oxytitanium phthalocyanine particles is, for example, a method of dispersing the oxytitanium phthalocyanine particles in a powdery state or adding a polymer solution of the binder resin as it is, and simultaneously dispersing the oxytitanium phthalocyanine particles. Any method such as a method of mixing in a polymer solution or a method of mixing a polymer solution in a dispersion may be used.

Thus, the coating solution for the charge generation layer is prepared. As a method for applying the charge generation layer coating solution to the conductive support, a known coating method can be used. For example, dip coating, spray coating, ring coating, or the like can be used. Of these, dip coating is desirable from the viewpoint of the stability of Y-type TiOPc and the ease of coating.

The thickness of the charge generation layer is 0.1 μm to
It is preferably 10 μm, and particularly preferably from 0.5 μm to 2 μm from the viewpoint of sensitivity, manufacturing cost and the like.
When the photosensitive layer is formed with a single layer structure including only the charge generation layer, the thickness of the charge generation layer is preferably 5 μm to 40 μm. The charge transfer layer includes a charge transfer material and a binder resin. As the binder resin, the same resin as the charge generation layer can be used.

As the charge transfer material, known materials can be used. For example, electron-withdrawing compounds such as 2,4,7-trinitrofluorenone, tetracyanoquinodimethane, chloranil, dicyanovinyl-nitro-benzene derivative, carbazole, indole, imidazole, oxazole, pyrazole, oxadiazole, thiazole,
Heterocyclic compounds such as pyrazoline, aromatic amine derivatives such as dialkylaniline, diarylaniline, diallylaniline, and triphenylamine, hydrazone compounds, stilbene compounds, styryl compounds, and heavy compounds in which these components are incorporated in the main chain or side chain. An electron donating compound such as a coalescence can be used.

The mixing ratio of the charge transfer material to the binder resin is such that the charge transfer material is 5 to 500 parts per 100 parts by weight of the binder resin.
Used from parts by weight. Further, the charge transfer layer may contain, if necessary, an application inhibitor, a sensitizer, a lubricant and the like. The charge transfer layer coating solution can be adjusted using a known method.

After the formation of the charge generation layer, a coating solution for the charge transfer layer is applied. As a coating method, a method similar to the method of coating the charge generation layer can be employed. The thickness of the charge transfer layer is preferably from 10 μm to 40 μm,
A thickness of 5 μm to 30 μm is more preferable from the viewpoint of printing durability and the like. The intermediate layer is an anodized film, aluminum oxide,
Inorganic layers such as aluminum hydroxide, polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyimide,
An organic layer such as polyamide, a layer made of a hybrid material in which titanium oxide, zirconium oxide, or the like is finely dispersed in a resin is used.

The thickness of the intermediate layer is in the range of 0.1 μm to 20 μm, preferably 0.1 μm to 10 μm. The protective layer is not particularly limited as long as the characteristics of the electrophotographic photoreceptor are not impaired, and a known protective layer can be used.

[0022]

The electrophotographic photoreceptor of the present invention will be specifically described below with reference to examples. Example 1 To 10 parts by weight of oxytitanium phthalocyanine, 1,2-
140 parts by weight of dimethoxyethane was added to form a dispersion solution, a refrigerant was circulated around a container holding the dispersion solution, and the temperature of the dispersion solution was measured with an electronic thermometer attached to the container. While controlling the flow rate to maintain the liquid temperature of the dispersion solution at 3 ° C. to −1 ° C., dispersion treatment was performed for 5 hours using a sand grind mill. Next, 50% by weight of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denka butyral # 6000C),
A dispersion was prepared by mixing with a 2-dimethoxyethane solution.

Next, a charge generation layer was provided on an aluminum-deposited surface on which the dispersion was deposited on a polyester film so that the film thickness after drying was 0.4 μm by a bar coater. Next, 56 parts by weight of a hydrazone compound shown below was placed on the charge generation layer.

[0024]

Embedded image 14 parts by weight of the following hydrazone compound

[0025]

Embedded image And 1.5 parts by weight of the following cyano compound

[0026]

Embedded image And a solution prepared by dissolving 100 parts by weight of a polycarbonate resin (manufactured by Mitsubishi Chemical Corporation, trade name NOVAREX 7030A) in 100 parts by weight of tetrahydrofuran is applied by a film applicator, and charge transfer is performed so that the film thickness after drying becomes 17 μm. Layers were provided. The photoreceptor thus obtained is referred to as photoreceptor A.

Similarly, five photosensitive members were prepared. These photoconductor groups are referred to as A-1 to A-5. As the initial electrical characteristics of the photoreceptor, a charged voltage, half-life exposure sensitivity, and residual potential were measured using an electrostatic copying paper tester (Model SP-4, manufactured by Kawaguchi Electric Works, Ltd.).
28). That is, a charged voltage Vo when the photoreceptor is negatively charged by corona discharge with an applied voltage set so that a corona current is set to 22 μA in a dark place, and then white light having an illuminance of 1.0 lux is continuously exposed, The exposure amount (E1 / 5) required for the potential to decrease from -450 V to -90 V and the residual potential Vr 10 seconds after the exposure were measured.

Example 2 The procedure of Example 1 was repeated, except that the liquid temperature was maintained at 3 ° C. to -1 ° C. instead of 3 ° C. to -1 ° C. 1 to B-5). Comparative Example 1 The procedure of Example 1 was repeated except that the temperature of the solution was kept at 3 ° C. to −1 ° C., and the temperature was not controlled. C-5) was produced.

COMPARATIVE EXAMPLE 2 Instead of maintaining the liquid temperature in the range of 3 ° C. to −1 ° C. in Example 1, the liquid temperature was set to 10 ° C. or lower and −3 ° C. or higher and the temperature was not controlled. The same operation is performed, and the photosensitive member D
(D-1 to D-5) were produced. Next, Table 1 shows the measurement results of the electrical characteristics.

[0030]

[Table 1] As is evident from Table 1, the electrophotographic photoreceptor obtained in Example 1 had good and excellent characteristics, and in Example 2 the characteristics and the reproducibility were sufficiently satisfactory. In Comparative Examples 1 and 2, the characteristics were slightly decoy and the reproducibility had some problems. This indicates that it is important to control the temperature of the dispersion liquid in the dispersion treatment of Y-type TiOPc to be constant.

[0031]

According to the present invention, a coating liquid using Y-type TiOPc having high characteristics as a charge generating material for an electrophotographic photosensitive member can be manufactured at an industrial production level without changing to a stable crystal form. A highly sensitive and uniform electrophotographic photosensitive member can be obtained.

Claims (3)

[Claims] 1. In an X-ray diffraction spectrum, Bragg angles (2θ ± 0.2 °) 9.2 °, 14.3 °, 24.0.
° and 27.3 °, wherein the oxytitanium phthalocyanine crystal having a diffraction peak at 27.3 ° is dispersed in a dispersion medium to form a photosensitive layer using a dispersion liquid. A method for producing an electrophotographic photoreceptor, wherein the temperature of the dispersion in the dispersion is maintained at −3 ° C. to 10 ° C., and the temperature change of the dispersion during the dispersion treatment is within 4 ° C. 2. The method according to claim 1, wherein the temperature of the dispersion is maintained at −3 ° C. to 3 ° C. 3. The method according to claim 1, wherein a temperature change of the dispersion is within 2 ° C.