JPH0782506A - Process for producing oxotitanium phthalocyanine crystal and electrophotographic photoreceptor containing the compound - Google Patents

Abstract

(57) [Abstract] [Purpose] An industrially advantageous production method for producing a specific oxotitanium phthalocyanine crystal suitable for an electrophotographic photoreceptor having a sufficient sensitivity to a long-wavelength light source such as a semiconductor laser, and the like. It is an object of the present invention to provide an electrophotographic photoreceptor containing the compound obtained by the method. [Structure] Acid-treated oxotitanium phthalocyanine is washed with alcohol and then solvent-treated to produce specific oxotitanium phthalocyanine crystals. Further, as a photoreceptor for electrophotography, a photosensitive layer containing the compound is provided on a conductive support.

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 oxotitanium phthalocyanine crystals and a high-sensitivity electrophotographic photoreceptor containing the compound obtained by the method.

[0002]

2. Description of the Related Art It has been widely known that phthalocyanine compounds have been used in electrophotographic photoconductors as photoconductive materials for electrophotography, but in recent years, non-impact printing technology has been developed. Along with this, expectations for laser beam printers using semiconductor lasers are increasing. Therefore, in response to these requirements, some have been reported that have absorption peaks in the long wavelength region of 700 nm or more and show high sensitivity in the near infrared region of semiconductor lasers depending on the type of central metal and crystal type. Cage,
The research and development is actively done.

Among them, the photoconductor using oxotitanium phthalocyanine is particularly excellent in carrier generation efficiency and mobility, and exhibits electrophotographic characteristics far superior to the photoconductors using other phthalocyanine compounds in the near infrared region. .

The crystalline form of oxotitanium phthalocyanine is described by Hiller et al. (Z. Krist., 159 , 1
73 (1982)), there is a crystal form called Phase I or II corresponding to stable β-type and metastable α-type, and which crystal form can be obtained is particularly dependent on the production conditions. It is generally known that it depends on heating conditions, the type of solvent to be treated, or mechanical strain.

Further, an α-type oxotitanium phthalocyanine is made into an aqueous suspension, and an aromatic hydrocarbon solvent is added thereto and heat-treated to obtain a Bragg angle (2θ) of 27.3 ° in an X-ray diffraction spectrum. It is possible to obtain a crystalline oxotitanium phthalocyanine which is not classified into α-type or β-type and has a strong peak in JP-A-63-
It is described in Japanese Patent No. 20365.

As described above, there are various crystal forms of oxotitanium phthalocyanine, and there are large differences in the crystal forms, that is, in the charging property, dark decay, sensitivity, etc., which are the characteristics of the electrophotographic photoreceptor, depending on the processing conditions. Known to be.

Conventionally, as a method for converting the crystalline form obtained by the method of the present invention, solvent treatment of acid-treated oxotitanium phthalocyanine with acetone, methyl ethyl ketone or the like has been carried out. At this time, as the acid-treated oxotitanium phthalocyanine, for example, after the reaction of phthalonitrile and titanium tetrachloride, oxotitanium phthalocyanine obtained by hydrolysis is dissolved in sulfuric acid, and the solution is poured into ice water to obtain a precipitate. The product is filtered, then washed thoroughly with water until it becomes neutral, and then dried.
In particular, nothing was clarified about the solvent washing of the acid-treated oxotitanium phthalocyanine. But,
As a result of detailed examination of the electrophotographic properties of the pigment obtained by solvent-cleaning the acid-treated oxotitanium phthalocyanine and using it, the acid-treated oxotitanium phthalocyanine was crystallized as it was without being washed with the solvent. Subsequent investigation revealed that the use of a pigment obtained by solvent treatment for electrophotographic photoreceptor in electrophotographic photoreceptor has an adverse effect on electrophotographic characteristics, which is considered to be due to impurities remaining in the pigment. Became.

[0008]

DISCLOSURE OF THE INVENTION The present invention involves washing acid-treated oxotitanium phthalocyanine with a specific solvent,
By heating and stirring it together with a specific processing solvent, it is possible to obtain an oxotitanium phthalocyanine crystal suitable for an electrophotographic photoreceptor, which has sufficient sensitivity and stable electrophotographic characteristics with respect to a long-wavelength light source such as a semiconductor laser. It is an object of the present invention to provide an industrially advantageous production method of producing a compound with high purity and a high yield, and an electrophotographic photoreceptor containing the compound obtained by the method.

[0009]

According to the present invention, acid-treated oxotitanium phthalocyanine is washed with alcohol and dried, and then heat-treated with acetonitrile or cyclohexanone or ethyl cellosolve to obtain a Bragg angle (X-ray diffraction spectrum in an X-ray diffraction spectrum. 2θ ± 0.2 °)
7.6 °, 10.3 °, 12.7 °, 16.3 °, 2
It shows strong diffraction peaks at 2.7 °, 24.3 °, 25.5 °, and 28.6 °, and when the pigment obtained is used for an electrophotographic photoreceptor, its electrophotographic characteristics are very stable. And a novel method for producing an oxotitanium phthalocyanine crystal having the feature of being characterized, and an electrophotographic photoreceptor containing the compound obtained by the method.

[0010]

In the method for producing an oxotitanium phthalocyanine pigment of the present invention, impurities are removed without affecting the crystal form by washing the acid-treated oxotitanium phthalocyanine pigment with alcohol before crystallizing it. Therefore, a highly pure product can be produced in good yield and industrially advantageously.

Further, since the electrophotographic photoreceptor containing the compound of the present invention uses the above-mentioned high-purity crystal as a charge generating material, it has high sensitivity, good chargeability and charge retention, and low residual potential. Also, the fluctuation due to repetition, which has been a problem in the past, will be small.

[0012]

EXAMPLES The present invention will be described more specifically below with reference to examples.

Example 1 100 g of phthalonitrile was added to 1
-Dissolve partly in 770 ml of chloronaphthalene and add 24 ml of titanium tetrachloride dropwise under stirring in a nitrogen atmosphere. After that, the temperature is gradually increased, and the mixture is heated at 200 to 220 ° C. for 3 hours and continuously stirred. Then, it is left to cool, and suction filtration is performed at 130 ° C. The filtered substance is further washed with 200 ml of 1-chloronaphthalene heated to 100 ° C. This is further washed with ethanol until the filtrate is no longer colored.

Next, the obtained dichlorotitanium phthalocyanine is gently refluxed with 400 ml of ammonia water and 400 ml of water for 1 hour with stirring. Then cool down,
Suction filter and wash thoroughly with water. The filtered product is hot-suspended (80 ° C.) with 800 ml of water for 1 hour under stirring, cooled and filtered by suction. This hot suspension treatment is repeated twice more. After that, vacuum drying is performed at 50 ° C. to obtain 82 g of crude oxotitanium phthalocyanine.

15 g of the obtained crude oxotitanium phthalocyanine is gradually added to 300 g of sulfuric acid while cooling in an ice water bath. After stirring for 1 hour, the mixture is suction-filtered with a glass filter and the filtrate is gradually added to 5 l of ice water while stirring. The precipitate obtained is filtered off with suction and washed thoroughly with distilled water until the filtrate becomes acidic to almost neutral. After that, the filtered substance is stirred with 300 ml of ethanol at room temperature for 1 hour, and then the pigment is separated by a centrifuge. After performing this operation once more, the pigment is vacuum dried at 30 ° C.

After the acid treatment and alcohol washing, oxotitanium phthalocyanine was placed in a 500 ml three-necked flask and heated with stirring with 300 ml of acetonitrile.
Reflux for 0 hours. Then, the mixture is cooled to room temperature, separated by a centrifuge, and vacuum dried. The X-ray diffraction spectrum of the obtained oxocytitanium phthalocyanine (yield 11.5 g) is shown in FIG.

As is apparent from FIG. 1, the Bragg angle (2θ
± 0.2 °) 7.6 °, 10.3 °, 12.7 °, 1
6.3 °, 22.7 °, 24.3 °, 25.5 °, 2
It had a strong diffraction peak at 8.6 °.

FIG. 2 is a spectrum of acid-treated oxotitanium phthalocyanine. (Example 2) Oxotitanium phthalocyanine prepared by the same method as in Example 1 and subjected to acid treatment and alcohol washing was placed in a 500 ml three-necked flask and refluxed with 300 ml of cyclohexanone for 8 hours under heating and stirring. Then, the mixture is cooled to room temperature, separated by a centrifuge, and dried in vacuum.
The X-ray diffraction spectrum of the obtained oxotitanium phthalocyanine is shown in FIG.

Example 3 Oxotitanium phthalocyanine prepared by the same method as in Example 1 and subjected to acid treatment and washed with alcohol was placed in a 500 ml three-necked flask and refluxed with 300 ml of ethyl cellosolve under heating and stirring for 20 hours. Then, the mixture is cooled to room temperature, separated by a centrifuge, and dried in vacuum. The X-ray diffraction spectrum of the obtained oxotitanium phthalocyanine is shown in FIG.

(Example 4) On an aluminum plate washed with acetone, 0.8 g of oxotitanium phthalocyanine crystals produced in Example 1, 0.2 g of fluororesin and 0.2 g of polyvinyl butyral resin were mixed with 38.
This was dispersed together with 8 g by a sand grind mill, and this dispersion was applied onto an aluminum plate so that the film thickness after drying would be 0.1 μm to form a charge generation layer.

On the charge generation layer, 1,1-bis (P-
5 g of diethylaminophenyl) -4,4-diphenylbutadiene, 5 g of polycarbonate resin (trade name PCZ-300 manufactured by Mitsubishi Gas Chemical Co., Inc.) and 35 g of dichloromethane are applied so that the film thickness after drying is 20 μm. Then, an electrophotographic photoreceptor having a laminated photosensitive layer was obtained.

An electrostatic copying paper test apparatus (model EPA-810 manufactured by Kawaguchi Electric Co., Ltd.) was used to measure the electrostatic characteristics of this photosensitive member.
0) was used. The measurement conditions are corona current -3
The initial charging potential when the photosensitive member is negatively charged in the dark by corona discharge with an applied voltage set to 0 μA is Vmax
(V), the surface potential after 1 second of dark decay is V0 (V), and the charge retention rate after 1 second of dark decay is DDR (%).
Irradiation with monochromatic light with energy of 2.1 μJ / cm ² · sec having a peak at 0 nm for 4 seconds, at which time the surface potential is 1
The exposure amount to become / 2V0, 1 / 5V0 is E1 / 2, E1 / 5 (μJ
/ Cm ² ), and the surface potential after 4 seconds of exposure was taken as the residual potential V _R (V). The results are shown in (Table 1).

[0023]

[Table 1]

Example 5 Using the oxotitanium phthalocyanine produced in Example 2, an electrophotographic photosensitive member was produced in the same manner as in Example 4, and its electrostatic characteristics were measured. The results are shown in (Table 1).

Example 6 Using the oxotitanium phthalocyanine produced in Example 3, an electrophotographic photosensitive member was produced in the same manner as in Example 4, and its electrostatic characteristics were measured. The results are shown in (Table 1).

(Application Example 1) Using the sample of Example 4 and repeating 1000 times under the same measurement conditions, the initial charge potential, half-exposure dose, dark decay, residual potential, etc. all show little fluctuation. It shows stable results.
The result is shown in FIG.

The symbols in the figure are the same as those used in Example 4, but only V _R is the residual potential after 2 seconds of exposure.

Further, the samples of Examples 5 and 6 were also repeatedly tested 1000 times.
As with the sample, the results were stable with little fluctuation.

(Comparative Example 1) In the synthetic method of Example 1, oxotitanium phthalocyanine obtained by subjecting oxotitanium phthalocyanine after acid treatment to ethanol treatment without rinsing was used. Then, an electrophotographic photosensitive member was produced in the same manner as in Example 4, and its electrostatic characteristics were measured. The results are shown in (Table 1).

Further, using the above electrophotographic photoreceptor, 100
The test was repeated 0 times, and the results are shown in FIG. As is clear from Table 1 and FIG. 6, it can be seen that by washing the oxotitanium phthalocyanine pigment after the acid treatment, the charging property and E1 / 2 are slightly improved, and the electrophotographic characteristics at the time of repetition are very stable. .

[0031]

As described above, according to the present invention, the acid-treated oxotitanium phthalocyanine is washed with alcohol and then treated with a solvent to obtain a Bragg angle (2θ).
± 0.2 °) 7.6 °, 10.3 °, 12.7 °, 1
6.3 °, 22.7 °, 24.3 °, 25.5 °, 2
An oxotitanium phthalocyanine crystal having a strong diffraction peak at 8.6 ° can be produced in good yield, and an electrophotographic photoreceptor using the oxotitanium phthalocyanine crystal obtained by this method as a charge generating material has a high yield. It is used as a highly durable photoreceptor because it has high sensitivity, good chargeability and charge retention rate, low residual potential, little variation due to repetition, which has been a problem in the past, and stable results. Further, since it exhibits high sensitivity in the region of 750 to 800 nm, it is suitable as a photoconductor for a semiconductor laser printer, which has been increasingly required in recent years.

[Brief description of drawings]

FIG. 1 is a diagram showing an X-ray diffraction spectrum of crystalline oxotitanium phthalocyanine obtained in the first example of the present invention.

FIG. 2 is a diagram showing an X-ray diffraction spectrum of acid-treated oxotitanium phthalocyanine.

FIG. 3 is a diagram showing an X-ray diffraction spectrum of crystalline oxotitanium phthalocyanine obtained in the second example of the present invention.

FIG. 4 is a diagram showing an X-ray diffraction spectrum of crystalline oxotitanium phthalocyanine obtained in the third example of the present invention.

FIG. 5 is a repeating characteristic diagram of the electrophotographic photoreceptor obtained in Example 4 of the present invention.

FIG. 6 is a repetitive characteristic diagram of an electrophotographic photoreceptor obtained by the method described in Comparative Example of the present invention.

Claims (8)

[Claims] 1. An acid-treated oxotitanium phthalocyanine is washed with alcohol, dried and then treated with a solvent to obtain a Bragg angle (2θ ± 0.2 °) of 7.6 °, 10.3 in an X-ray diffraction spectrum. °, 12.7
°, 16.3 °, 22.7 °, 24.3 °, 25.5
A process for producing an oxotitanium phthalocyanine crystal, which comprises obtaining a crystal having a strong diffraction peak at 2 ° and 28.6 °. 2. The method for producing an oxotitanium phthalocyanine crystal according to claim 1, wherein the solvent treatment is heat treatment with acetonitrile. 3. The method for producing an oxotitanium phthalocyanine crystal according to claim 1, wherein the solvent treatment is heat treatment with cyclohexanone. 4. The method for producing an oxotitanium phthalocyanine crystal according to claim 1, wherein the solvent treatment is heat treatment with ethyl cellosolve. 5. An electrophotographic photoreceptor having at least a photosensitive layer in which oxotitanium phthalocyanine is dispersed in a binder resin, wherein the oxotitanium phthalocyanine is prepared by washing the acid-treated oxotitanium phthalocyanine with alcohol and drying. Bragg angle (2θ ± 0.2 °) of 7.6 °, 10.3 °, 1 in X-ray diffraction spectrum obtained by solvent treatment.
2.7 °, 16.3 °, 22.7 °, 24.3 °, 2
An electrophotographic photoreceptor, which is a crystal having strong diffraction peaks at 5.5 ° and 28.6 °. 6. A photoreceptor for electrophotography using an oxotitanium phthalocyanine crystal according to claim 5, wherein the solvent treatment is a heat treatment with acetonitrile. 7. The electrophotographic photoconductor using the oxotitanium phthalocyanine crystal according to claim 5, wherein the solvent treatment is a heat treatment with cyclohexanone. 8. The electrophotographic photoreceptor using the oxotitanium phthalocyanine crystal according to claim 5, wherein the solvent treatment is a heat treatment with ethyl cellosolve.