JP2867563B2 - Manufacturing method of electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an electrophotographic photosensitive member using a specific oxytitanium phthalocyanine crystal as a charge generating agent.

[Prior Art] Conventionally, phthalocyanines and metal phthalocyanines exhibit good photoconductivity and have been used, for example, in electrophotographic photoreceptors. In recent years, laser printers that 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, and photoconductors that can withstand the demands have been actively developed. is there.
In particular, in recent years, various types of methods of using a semiconductor laser as a light source, which has remarkably progressed among laser beams, have been tried.
Since the wavelength of the light source is around 800 nm, there is a strong demand for a photoreceptor having high sensitivity to long wavelength light around 800 nm. Known organic photoconductive materials that satisfy this requirement include methine squaric acid dyes, cyanine dyes, pyrylium dyes, thiapyrylium dyes, polyazo dyes, and phthalocyanine dyes. Among these, methine squaric acid dyes, cyanine dyes,
Pyrylium-based dyes and thiapyrylium-based dyes are relatively easy to increase the spectral sensitivity to a longer wavelength, but lack practical stability such as repeated use, and polyazo dyes are difficult to increase the absorption wavelength, and There are manufacturing difficulties. On the other hand, phthalocyanine dyes can be synthesized relatively easily, 60
Vigorous research due to the fact that it has an absorption peak in the long wavelength range of 0 nm or more, and that several types of semiconductor lasers exhibiting high sensitivity in the wavelength range have been published, whose spectral sensitivity varies depending on the metal and crystal system. Development is taking place.

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 form. Some examples have been reported. For example, it is reported that oxytitanium phthalocyanine has various crystal forms, and there is a great difference in chargeability, dark decay, sensitivity, etc. due to the difference in the crystal forms. In JP-A-59-49544, the crystal form of oxytitanium phthalocyanine includes Bragg angles (2θ ± 0.2 °) = 9.2 °, 13.1 °, 2 °
Those which give strong diffraction peaks at 0.7 °, 26.2 ° and 27.1 ° are described as suitable, and the 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 ゜, 28.6
゜ indicates a case where a strong diffraction peak is shown. Further, in Japanese Patent Application Laid-Open No. 64-17066, as the crystal form of oxytitanium phthalocyanine, the main peak of the Bragg angle (2θ ± 0.2 °) is at least 9.5 ° ± 0.2 °, 9.7 ° ± 0.2 °, 1 °
1.7 ± 0.2, 15 ± 0.2, 23.5 ± 0.2, 24.1 ±
It is described that those having 0.2 ° and 27.3 ° ± 0.2 ° are preferable.

The present inventors have conducted detailed studies and evaluations on various crystal forms of such oxytitanium phthalocyanine. In particular, oxytitanium phthalocyanine showing a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° is particularly important. It was found that the film had high sensitivity and excellent characteristics. Several methods have been reported for producing oxytitanium phthalocyanine exhibiting such an X-ray diffraction spectrum. For example, in Japanese Patent Application No. Sho 60-12194, dichlorotitanium phthalocyanine is converted to the pH of the filtrate.
And that the oxytitanium phthalocyanine having a main diffraction peak at 27.3 ° can be obtained by sufficiently washing the suspension with hot water until the value becomes about 5 to 7.

JP-A-63-20365 discloses a method in which an aromatic hydrocarbon solvent is added to an aqueous suspension of α-type oxytitanium phthalocyanine, followed by heat treatment.

Further, Japanese Patent Application Laid-Open No. Sho 64-17066 discloses a method for obtaining α-oxytitanium phthalocyanine by grinding with a sand grinder together with a grinding aid and a dispersion medium.

[Problem to be Solved by the Invention] However, this Bragg angle (2θ ± 0.2 °) is 27.
The oxytitanium phthalocyanine showing a clear diffraction peak in 3 ゜ was examined in more detail, and as a result, the crystal form was metastable, and when preparing the dispersion for coating the charge generation layer, other conditions were considered depending on the dispersion conditions. It has been found that it is easy to change to a more stable crystal form, and the good electrical characteristics originally possessed by this crystal form are impaired at this stage.

[Means for Solving the Problems] Therefore, various studies were made on dispersion conditions in order to prepare a stable dispersion while maintaining the crystal form of oxytitanium phthalocyanine having such a crystal form. The temperature during the treatment is at least above the freezing point of the dispersion medium and below room temperature, preferably below the freezing point of the dispersion medium and below 10 ° C. The present inventors have found that a dispersion can be prepared while holding the mold, and have reached the present invention.

That is, the gist of the present invention is a method for producing an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the X-ray diffraction spectrum has a Bragg angle (2θ ± 0.2 °) of 2 mm.
The crystal of oxytitanium phthalocyanine showing a clear diffraction peak at 7.3 ° is at least the freezing point of the dispersion medium and at room temperature or less, preferably at least the freezing point of the dispersion medium and at least 10 ° C. Forming a photosensitive layer using a dispersion liquid subjected to a dispersion treatment in (1).

[Operation] 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) (Wherein X represents a halogen atom, and n represents a number from 0 to 1).

In the general formula (I), those wherein X is a chlorine atom and n is from 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, for example, the following reaction formula (1) or (2).

That is, 1,2-dicyanobenzene and a titanium halide are heated and reacted in an inert solvent. As the titanium compound, titanium tetrachloride, titanium trichloride, titanium tetrabromide and the like can be used, but titanium tetrachloride is preferably used. As the inert solvent, trichlorobenzene, α-chloronaphthalene, β-chloronaphthalene, α
-High boiling solvents which are inert to the reaction such as methyl naphthalene, methoxy naphthalene, diphenyl ether, diphenyl methane, diphenyl ethane, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, and triethylene glycol dialkyl ether are preferred. The reaction temperature is usually from 150 ° C to 300 ° C, preferably from 180 ° C to 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, the solvent used in the reaction is removed by washing with an inert solvent such as alcohols such as methanol, ethanol and isopropyl alcohol, and ethers such as tetrahydrofuran and diethyl ether. Next, the obtained dichlorotitanium phthalocyanine is hydrolyzed into oxytitanium phthalocyanine. The oxytitanium phthalocyanine thus formed is subjected to amorphous treatment by, for example, an acid paste method or a mechanical grinding method using a sand grind mill, and then suspended in water, and chlorobenzene,
By adding and heating an aromatic hydrocarbon solvent such as dichlorobenzene, toluene, and xylene, the X-ray diffraction spectrum shows that the Bragg angle (2θ ± 0.2 °) is 2 °.
An oxytitanium phthalocyanine crystal having a main diffraction peak at 7.3 ° 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, for example, by appropriate treatment from other crystalline oxytitanium phthalocyanine. Although it can be produced, any crystalline oxytitanium phthalocyanine produced by any production method shows a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in the X-ray diffraction spectrum, and FIG. 1 as long as they belong to the same crystal type as the crystal whose X-ray diffraction spectrum is shown. Normally, it shows relatively clear diffraction peaks other than 27.3 ゜, around 9.5 ゜ and 24.1 ゜.

In the present specification, the “clear diffraction peak” refers to a peak having the highest (highest) peak intensity or the sharpest peak in the powder X-ray diffraction spectrum. The X-ray diffraction spectrum of the oxytitanium phthalocyanine crystal produced by the method of the present invention shows a clear diffraction peak at a Bragg angle (2θ ± 0.2) 27.3 ° as shown in FIGS. 1 and 2, and 9.7 ° and 24.1 °. Other diffraction peaks such as ゜ vary depending on manufacturing conditions, and in some cases,
Although the intensity may be stronger than the peak at 27.3 ° C, it is a relatively broad peak.

As an index indicating the clarity (sharpness) of each diffraction peak, an S value is calculated and used as shown in the following equation from the shape of the peak on the chart of the X-ray diffraction spectrum.

Next, when dispersing the oxytitanium phthalocyanine of such a crystal type in a dispersion medium, the temperature of the dispersion medium is not less than the freezing point of the dispersion and not more than room temperature, preferably not less than the freezing point of the dispersion medium. In addition, it is cooled to 10 ° C. or lower, and is finally adjusted as a coating liquid for coating the photosensitive layer in a state of being mixed with the binder resin.

As the cooling method, any of known methods such as air cooling, water cooling, ice water cooling, a method of adding salt to ice water cooling, a method using dry ice and methanol, and the like may be used.

Various solvents may be used as the dispersion medium, as long as the crystal form of oxytitanium phthalocyanine is not changed. 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 or Two or more kinds can be used as a mixture.

The amount of the dispersion medium to be 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 oxytitanium phthalocyanine in the dispersion at the time of dispersion is 3 to 20wt
%, More preferably about 4 to 20 wt%.

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. These partially crosslinked cured products 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.

As a method of mixing the binder resin and the oxytitanium phthalocyanine particles, for example, a method of dispersing the oxytitanium phthalocyanine particles at the same time as dispersing the binder resin as a powder or a polymer solution thereof, and dispersing the dispersion liquid of the binder resin 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.

Next, the dispersion obtained here may be diluted with various solvents in order to make the liquid properties suitable for coating, as long as the crystal form of oxytitanium phthalocyanine is not changed. As such a 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 based on 100 parts by weight of the resin. In addition, a charge transfer agent can be included as needed. As the charge transfer agent, for example, 2,4,7-trinitrofluorenone, an electron withdrawing substance such as tetracyanoxydimethane, cerbazole, indole, imidazole, oxazole, pyrazole, oxadiazole,
Heterocyclic compounds such as pyrazoline and thiadiazole; electron-donating substances such as aniline derivatives, hydrazone compounds, aromatic amine derivatives, stilbene derivatives, and polymers having a group consisting of these compounds in the main chain or side chain. . The ratio of the charge transfer agent to the binder resin is such that the charge transfer substance is used in a range of 5 to 500 parts by weight based on 100 parts by weight of the binder tree.

When the X-ray spectrum is measured using the dispersion thus prepared in the form of a thin film, for example, the Bragg angle (2θ ± 0.2
In (ii), the peak intensity around 9.5 ° may appear to change, but this does not involve a change in the crystal form and is not particularly hindered. That is, as long as the main peak shows a clear diffraction peak at 27.3 °, the intensity of the other peaks may be changed.

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 the conductive support. Forming a moving layer, forming a charge generation layer thereon using the dispersion liquid to form a photosensitive layer, or forming a charge generation layer using the dispersion liquid on a conductive support to form a photosensitive layer, The photosensitive layer can be formed by any one of the above structures. When the photosensitive layer is formed by laminating the charge transfer 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 10 μm to 40 μm. 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 in the range of 5 to 40 μm.

When the charge transfer layer is provided, the materials exemplified as the charge transfer agent can be used as the charge transfer agent used therein. A binder resin is blended with these charge transfer agents as needed. As the binder resin, for example, the binder resins exemplified above 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, but as the conductive support, aluminum, stainless steel, copper, a metal material such as nickel, aluminum, copper, palladium on the surface,
An insulative support such as polyester film, paper, or glass provided with a conductive layer such as tin oxide or indium oxide is used. A well-known barrier layer which is usually used may be provided between the conductive support and the charge generation layer.

As the barrier layer, for example, an anodized aluminum film, an inorganic layer such as aluminum oxide and aluminum hydroxide, an organic layer such as polyvinyl alcohol, casein, polyvinyl pyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, etc. Layers are used. Barrier layer thickness from 0.1 μm to 2
It is most effective to use 0 μm, preferably in the range of 0.1 μm to 10 μm.

[Effects of the Invention] According to the production method of the present invention, when preparing a coating solution for coating a photosensitive layer, a coating solution having excellent dispersibility and excellent coatability without changing the crystal form of oxytitanium phthalocyanine. Can be prepared. Further, the electrophotographic photoreceptor obtained according to the present invention shows a particularly high sensitivity as compared with those which have been practically used so far, and has a residual potential,
Other electrical characteristics such as chargeability also show good characteristics.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Production Examples and Examples.

[Production Example] 97.5 g of phthalodinitrile was added to 750 ml of α-chloronaphthalene
Then, under a nitrogen atmosphere, 22 ml of titanium tetrachloride was added dropwise. After the dropwise addition, the mixture was heated and reacted at 200 to 220 ° C. for 3 hours with stirring, then allowed to cool, filtered while hot at 100 to 130 ° C., and washed with 200 ml of α-chloronaphthalene heated to 100 ° C. 2 more
Hot suspension washing with 100 ml of N-methylpyrrolidone (100 ° C, 1
Time) three times. Then, wash with 300 ml of methanol at room temperature and wash with 500 ml of methanol for 1 hour.
Performed times. The oxytitanium phthalocyanine thus obtained was subjected to a grinding treatment for 20 hours in a sand grind mill, 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.

The X-ray diffraction spectrum of the oxytitanium phthalocyanine thus obtained is shown in FIG. As is apparent from FIG. 1, a sharp peak is shown at 27.3 ° at the Bragg angle (2θ ± 0.2 °).

Example 1 Oxytitanium phthalocyanine 10 produced in Production Example
200 parts by weight of n-propanol are added to the parts by weight, and the liquid temperature is cooled to 5 ° C. or less by ice-water cooling, and the mixture is sand-milled.
Pulverization and atomization and dispersion treatment were performed for 10 hours. Next, a dispersion was prepared by mixing 5 parts by weight of a polyvinyl butyral (Denka Butyral # -6000C, manufactured by Denki Kagaku Kogyo KK) with a 10% methanol solution.

The dispersion A thus obtained was prepared on a glass substrate to prepare a sample A provided with a charge generation layer so that the film thickness after drying was 0.4 μm. The X-ray diffraction spectrum measured in this state is shown in FIG. 2, but no change in the crystal form is observed.

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 the following hydrazone compound was placed on the charge generation layer. The following hydrazone compound 14 parts by weight, And 1.5 parts by weight of the following cyano compound And 100 parts by weight of polycarbonate resin (manufactured by Mitsubishi Chemical Corporation, trade name NOVAREX 7030A) in 1,4-dioxane 100
A solution dissolved in 0 parts by weight was applied by a film applicator, and a charge transfer layer was provided so that the film thickness after drying was 17 μm. The photoreceptor thus obtained is referred to as photoreceptor A.

As the initial electrical characteristics of the photoreceptor, the charged voltage, half-exposure sensitivity and residual potential were measured by an electrostatic copying paper tester (model SP-428, manufactured by Kawaguchi Electric Works).

That is, in a dark place, the charged voltage Vo when the photoreceptor is negatively charged by corona discharge with an applied voltage set so that the corona current becomes 22 μA, and then white light having an illuminance of 1.0 lux is continuously exposed to the surface potential. The amount of exposure (E1 / 5) required to decrease from −450 V to −90 V and the residual potential Vr 10 seconds after exposure were measured. The results are shown in Table 1, and it can be seen that the sensitivity is high.

Comparative Example-1 A sample B and a photoreceptor B were prepared in the same manner as in Example 1 except that the temperature was changed to room temperature instead of cooling to 5 ° C. or lower. The X-ray diffraction spectrum of Sample B is shown in FIG. 3, which clearly shows that the spectrum pattern has changed and the crystal form has changed.

Next, the measurement results of the electrical characteristics are shown in Table 1. As shown in Table 1, the characteristics were lower in sensitivity and higher in residual potential than those in Examples.

[Brief description of the drawings]

FIG. 1 shows the X-ray diffraction spectrum of oxytitanium phthalocyanine obtained in the production example, and FIGS. 2 and 3 show the X-ray diffraction spectra of Sample A and Sample B, respectively.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-217462 (JP, A) JP-A-3-181570 (JP, A) JP-A 1-292066 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G03G 5/00-5/16

Claims (1)

(57) [Claims] 1. A method for producing an electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the X-ray diffraction spectrum shows a Bragg angle (2θ ± 0.2 °) of 27.3 °. A crystal layer of oxytitanium phthalocyanine exhibiting a precipitation peak, the photosensitive layer is formed by using a dispersion obtained by performing a dispersion treatment in a dispersion medium cooled to 10 ° C. or lower, which is higher than the freezing point of the dispersion medium. A method for producing an electrophotographic photoreceptor.