JPH07145329A - Production of oxotitanium phthalocyanine crystal and electrophotographic photoreceptor containing the compound - Google Patents

Abstract

PURPOSE:To obtain an oxotitanium phthalocyanine crystal which has sufficient sensitivity to a long-wavelength light source, e.g. a semiconductor laser, and stable electrophotographic characteristics and is suited for use in an electrophotographic photoreceptor by washing and heating an acid-treated oxotitanium phthalocyanine with specific solvents. CONSTITUTION:An oxotitanium phthalocyanine treated with an acid is washed with an alcohol, dried, and then heated in Ethyl Cellosolve. This phthalocyanine is suspended in and washed with heated cyclohexanone, and then suspended in and washed with heated ethanol. Thus, crystals can be obtained which give an X-ray diffraction spectrum having intense diffraction peaks at Bragg angles (2 theta+ or -0.2 deg.) of 7.6 deg., 10.3 deg., 12.7 deg., 16.3 deg., 22.7 deg., 24.3 deg., 25.5 deg., and 28.6 deg..

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, the method of washing the acid-treated oxotitanium phthalocyanine with a solvent and the method of washing the pigment after the solvent treatment for crystal conversion have not been clarified at all. However, the acid-treated oxotitanium phthalocyanine was washed with a solvent, and as a result of detailed examination of the electrophotographic characteristics of the pigment obtained by the solvent treatment using the same, the acid-treated oxotitanium phthalocyanine was not washed with a solvent, and Subsequent investigations revealed that if the pigment after solvent treatment for crystal conversion is used as it is in the electrophotographic photoreceptor, it may have an adverse effect on the electrophotographic characteristics, which is probably 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,
An electrophotographic photosensitive member having sufficient sensitivity and stable electrophotographic characteristics to a long-wavelength light source such as a semiconductor laser by heating and stirring it with a specific processing solvent and then washing the pigment with a predetermined solvent. A method for producing an oxotitanium phthalocyanine crystal suitable for a high-purity and high-yield industrially advantageous production method, and an electrophotographic photoreceptor containing the compound obtained by the method. is there.

[0009]

In the present invention, acid-treated oxotitanium phthalocyanine is washed with alcohol, dried, heat-treated with ethyl cellosolve, and then heat-suspended and washed with cyclohexanone and ethanol. In the line diffraction spectrum, the Bragg angle (2θ
± 0.2 °) 7.6 °, 10.3 °, 12.7 °, 1
6.3 °, 22.7 °, 24.3 °, 25.5 °, 2
Novel production of oxotitanium phthalocyanine crystal having a strong diffraction peak at 8.6 ° and being characterized in that when the obtained pigment is used in an electrophotographic photoreceptor, its electrophotographic characteristics are very stable. A method and an electrophotographic photoreceptor containing the compound obtained by the method.

[0010]

The method for producing an oxotitanium phthalocyanine pigment of the present invention comprises washing the acid-treated oxotitanium phthalocyanine pigment with alcohol before crystallizing it,
Furthermore, since impurities are effectively removed without affecting the crystal form by washing with a specific solvent even after the crystal transition, a highly pure product can be produced in good yield and industrially advantageous. Is something that can be done.

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. In addition, the variation 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 warmed 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 is placed in a 500 ml three-necked flask and refluxed with 300 ml of ethyl cellosolve under heating and stirring for 20 hours. Then, cool to room temperature and separate with a centrifuge. This was washed twice with 300 ml each of cyclohexanone under stirring (60 ° C., 1 hour) under heat, and finally, twice with 300 ml each of ethanol (60 ° C., 1 hour). And vacuum dry. 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) 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 sand ground together with 38.8 g of isobutyl alcohol. The mixture was dispersed in a 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 photoreceptor.
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 amounts to become 1 / 2V ₀ and 1 / 5V ₀ are 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).

(Application Example 1) Using the sample of Example 2 and repeating 1000 times under the same measurement conditions, there was no change in initial charging potential, half exposure amount, dark decay, residual potential, etc. It shows very stable results. The result is shown in FIG.

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

(Comparative Example 1) Obtained by washing the oxotitanium phthalocyanine after acid treatment with ethanol in the synthetic method of Example 1 and solvent-treated cyclohexanone for crystal conversion and ethanol without washing with ethanol. An electrophotographic photosensitive member was produced by using the obtained oxotitanium phthalocyanine in the same manner as in Example 2, and its electrostatic characteristics were measured. The results are shown in (Table 1).

[0024]

[Table 1]

Further, the above electrophotographic photoconductor is used to obtain 100
Since the test was repeated 0 times, the results are shown in FIG. As is clear from FIG. 4, by washing the oxotitanium phthalocyanine pigment after the acid treatment and the solvent treatment for crystal conversion, the electrophotographic characteristics at the time of repetition are stabilized.

[0026]

As described above, according to the present invention, after acid-treated oxotitanium phthalocyanine is washed with alcohol, it is heat-treated with ethyl cellosolve, and then washed with cyclohexanone and ethanol to give a Bragg angle (2θ ± 2). 0.2 °) 7.6 °, 10.3 °, 1
2.7 °, 16.3 °, 22.7 °, 24.3 °, 2
Oxotitanium phthalocyanine crystals having strong diffraction peaks at 5.5 ° and 28.6 ° can be produced in high yield, and for electrophotography using the oxotitanium phthalocyanine crystals obtained by this method as a charge generating material. The photoconductor is used as a highly durable photoconductor because it has high sensitivity, good chargeability and charge retention rate, low residual potential, and shows stable results without fluctuation due to repetition, which has been a problem in the past. To be Also 750-800
Since it exhibits high sensitivity in the nm region, 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 an X-ray diffraction spectrum diagram of crystalline oxotitanium phthalocyanine obtained in the first example of the present invention.

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

FIG. 3 is a repeating characteristic diagram of the electrophotographic photosensitive member obtained in Example 2 of the present invention.

FIG. 4 is a repetitive characteristic diagram of an electrophotographic photoreceptor obtained by the method described in Comparative Example of the present invention.

Claims (2)

[Claims] 1. An acid-treated oxotitanium phthalocyanine is washed with alcohol, dried and then heat-treated with ethyl cellosolve, followed by washing with cyclohexanone and ethanol in a hot suspension in order to obtain a Bragg angle (2θ) in an X-ray diffraction spectrum. ± 0.2 °) 7.6 °, 1
0.3 °, 12.7 °, 16.3 °, 22.7 °, 2
A process for producing an oxotitanium phthalocyanine crystal, which comprises obtaining a crystal having strong diffraction peaks at 4.3 °, 25.5 °, and 28.6 °. 2. An electrophotographic photosensitive member having at least a photosensitive layer in which oxotitanium phthalocyanine is dispersed in a binder resin, wherein the oxotitanium phthalocyanine is washed with alcohol and dried with ethyl ether. Bragg angle (2θ ± 0.2 °) 7.6 in X-ray diffraction spectrum obtained by sequentially performing heat treatment with cellosolve and then hot suspension washing with cyclohexanone and ethanol.
°, 10.3 °, 12.7 °, 16.3 °, 22.7
A photoreceptor for electrophotography, which is a crystal showing a strong diffraction peak at °, 24.3 °, 25.5 °, and 28.6 °.