JP3286685B2 - Electrophotographic photosensitive member and method of manufacturing electrophotographic photosensitive member - 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 photosensitive member having separated functions, and more particularly to an electrophotographic photosensitive member having good productivity and excellent electrophotographic characteristics. More specifically, the composition of the charge generation layer using α-type oxotitanium phthalocyanine as the charge generation agent , the charge transport layer using the tetraphenylbutadiene compound and the diphenylhydrazone compound as the charge transport agent , the composition of the intermediate layer, and the production thereof It is about the method.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors have good charging characteristics and sensitivity, low dark decay, abrasion resistance, printing durability, and moisture resistance during repeated use, as well as infrared and corona discharge during exposure. It is also required to have good resistance to generated ozone and the like.

In general, an inorganic photoreceptor having a photosensitive layer containing an inorganic photoconductive material such as selenium or zinc oxide as a main component;
Organic photoconductors having a photosensitive layer mainly containing an organic photoconductive material such as poly-N-vinylcarbazole and phthalocyanine pigment are known, and the inorganic photoconductors have sensitivity, heat stability, durability and the like. However, due to its toxicity, there is a tendency to use organic photoconductive substances as materials for photosensitive layers of electrophotographic photoreceptors.

[0004] The layer structure is such that a function-separated organic electrophotographic photoreceptor having functions separated into a charge generation layer and a charge transport layer has excellent productivity and electrophotographic characteristics, and has a wavelength of laser light to be used. In recent years, sufficient sensitivity and charging characteristics can be obtained, and therefore, they are widely used in copiers, printers, facsimile machines and the like in recent years.

In a function-separated organic electrophotographic photosensitive member, a charge generation layer and a charge transport layer are generally formed in this order on a conductive support such as aluminum. If necessary, an intermediate layer may be provided between the conductive support and the charge generation layer.

The charge generation layer is formed by using a coating solution in which a charge generation agent and a binder are dispersed or dissolved in a solvent.
It is formed by a simple coating method such as spray coating and dip coating. The charge transport layer is similarly formed by a coating solution in which a charge transport agent and a binder are dissolved in a solvent.

[0007]

As for such an electrophotographic photosensitive member, it is a matter of course that an appropriate one for the electrophotographic photosensitive member should be selected for each layer constitution. Requires examination from the synergistic effect of the combination of the substances in each layer. That is, it is understood that the combination of the charge generating agent and the binder and the compounding ratio thereof, the combination of the charge transporting agent and the binder and the compounding ratio thereof, and the combination of the charge generating layer and the charge transport layer have an important effect on the electrophotographic characteristics. ing.

[0008] The solvent used in these coating liquids is that the charge generating layer coating liquid has good dispersibility of the charge generating agent and good solubility of the binder.
Further, in the charge transport layer coating solution, it is naturally required that the charge transport agent and the binder used have good solubility. However, when these layers are further coated, the solvent of the charge transport layer coating solution is required. If the solubility of the lower charge generation layer is high, the charge generation layer will be dissolved in the coating solution for the charge transport layer, resulting in poor productivity and adversely affecting electrophotographic characteristics.

That is, if the combination and the mixing ratio of the charge generating agent and the binder, the combination and the mixing ratio of the charge transporting agent and the binder, and the combination of the charge generating layer and the charge transport layer are not appropriate, the print density is low, Further, soiling may occur.

Further, a combination thereof, also as a blending ratio was originally correct, or distributed becomes bad by solvent used, also, the problem in productivity by Rukoto disintegrate soluble layer of the previous step In addition to adverse effects on electrophotographic properties.

Providing an intermediate layer between the conductive support and the charge generation layer is effective in preventing charge leakage. The coating material of the intermediate layer, adhesion between the conductive support such as aluminum, adhesive, and not only electrical insulation is required, is required to be not attacked by the solvent of the charge generation layer You. Conventionally, many examples have been published for the function-separated organic electrophotographic photoreceptor,
There is no invention showing an optimum case for these combinations, mixing ratios and solvents used.

First, the photosensitive materials used in the charge generation layer and the charge transport layer will be examined, and what kind of binder should be combined with them at what ratio will be examined. In examining the material of the charge generation layer, most of the oscillation wavelengths of currently operating semiconductor lasers are in the near infrared region (λ> 780 nm). Among such photoconductive materials that exhibit high sensitivity in the long wavelength region, oxo titanium phthalocyanine is attracting attention,
Various types are used, such as α-type, β-type, and unspecified. Among them, the present inventors focused on α-type oxotitanium phthalocyanine.

The α-type oxotitanium phthalocyanine has low sensitivity, poor potential stability, and has a problem that fogging easily occurs in an electrophotographic process using reversal development. Α-type is liable to shift to β-type when the polarity of the solvent is high. However, the α-type is not particularly low in sensitivity, and the point of low sensitivity can be compensated for by a charge transfer agent. Therefore, when oxotitanium phthalocyanine is used, high sensitivity is not an absolute requirement. The α-form preferably has a low residual potential.

Accordingly, an object of the present invention is to provide a function-separated electrophotographic photoreceptor using α-type oxotitanium phthalocyanine as a charge generating agent, which has good productivity and exhibits optimal electrophotographic characteristics. Agent, binder, solvent combination, to provide the compounding ratio,
As a result of various experiments, the present inventors have found the optimal combination (charge generating agent and binder, charge transporting agent and binder, these and solvent), and the mixing ratio.

[0015]

According to the present invention , (X) an infrared absorption spectrum of 729 c
m ^-1 , 752 cm ^-1 , 894 cm ^-1 , 971 cm ^-1 , 1070 c
It has strong absorption at m ^-1 , 1119 cm ^-1 and 1333 cm ^-1 ,
The ^{775cm -1, 802cm -1, 8 79cm} -1, 1 1 60cm
Has weak absorption in ^-1, (Y) CuKa ray (wavelength 1.54
1 °) in the X-ray diffraction spectrum 7.5 °, 10.2, 12.5, 1
30 to 70 parts by weight of an α-type oxotitanium phthalocyanine crystal composition having a strong diffraction peak at 6.3, 22.4, 24.2, 25.3, 28.6 degrees and an acetalization amount of 8
0 or more, formed by a charge generator containing 30 to 70 parts by weight of a polyvinyl butyral resin having an average degree of polymerization of 2000 or more.
A charge generation layer to be formed, 10 to 40 parts by weight of a tetraphenylbutadiene compound represented by the general formula ( Chemical Formula 1) and 10 parts by weight of a diphenylhydrazone compound represented by the general formula ( Chemical Formula 2)
~ 40 parts by weight, and further, 40 ~ 7 parts of polycarbonate resin
Charge formed by the charge transporting agent containing 0 parts by weight
Charge generation in an electrophotographic photoreceptor provided with a transport layer
Tetrahydrofuran as a solvent for the layer coating solution
Using (THF) as a solvent for the coating solution for the charge transport layer
As by this <br/> and using a mixed solution of toluene and methylene chloride, good productivity, it was possible to obtain good electrophotographic photoreceptor of the electrophotographic characteristics.

The polyvinyl butyral resin used for the binder of the charge generation layer according to the present invention is polyvinyl alcohol (PVA) obtained by saponifying a polyvinyl acetate resin.
Is reacted with butyraldehyde. When the amount of the binder in the charge generation layer is 30 parts by weight or less, the dark decay becomes large, and when the amount is 70 parts by weight or more, the sensitivity is insufficient. Therefore, 30 to 70 parts by weight is preferable.

Further, an intermediate layer of a polyamide resin having a coating amount of 1 to 8 g / m ² may be provided between the conductive support and the charge generation layer. When aluminum is used as the conductive support, the surface of the intermediate layer may be subjected to alumite processing.

JP-A-59-71057 discloses that a polycarbonate resin is excellent as a binder for the charge transport layer because of its tough film properties and the like. When the amount of the binder is 30 parts by weight or less, the initial charge level is low, the dark decay is large, and when the amount is 70 parts by weight or more, the sensitivity is poor. For this reason, there are problems such as soiling of the background and a low print density when used in an actual printer. Follow
Containing polycarbonate as binder for charge transport layer
Is preferably 30 to 70 parts by weight, and more preferably 40 to 60 parts by weight to obtain more preferable results.

The solvent used for the coating solution for the charge transport layer naturally has good solubility for the polycarbonate resin. However, if the drying speed is too high, the surface becomes uneven and the printing becomes uneven. If the drying speed is low, the productivity is not good. Further, it is necessary that the lower charge generation layer is not substantially dissolved during the coating step. From these points, a mixed solvent of toluene and methylene chloride is particularly preferable.

In the above-mentioned electrophotographic photoreceptor, when the coating amount of the charge generating layer is 0.1 g / m ² or less, a partial difference in the coating amount tends to appear as uneven printing,
Also, the sensitivity is not good. When it is 0.5 g / m ² or more, dark attenuation increases, so that 0.1 to 0.5 g / m ² is preferable.

Further, the coating amount of the charge transport layer is 20
When it is less than g / m ^2, dark decay becomes large and printing durability is poor. If it is 40 g / m ² or more, the charge transport efficiency becomes poor and sufficient contrast cannot be obtained. Therefore 2 0
~40g / m ² is preferred.

It is preferable to provide an insulating intermediate layer between the conductive support substrate and the charge generation layer in order to prevent leakage of the charge and control the charge potential. As the intermediate layer, a polyamide resin which is not substantially eroded by the solvent of the charge generating layer coating agent is used, and a coating amount of 1 g / m ² or more is required in order to prevent partial background fouling due to charge leakage. is there.

Further, as the conductive support, if aluminum is used, it is also possible to form the intermediate layer by the surface to anodized.

[0024]

The present invention uses α-type oxotitanium phthalocyanine as a charge generating agent, and therefore preferably exhibits high sensitivity in a long wavelength region and a low residual potential. The physical and chemical properties of the polyvinyl butyral resin used as a binder in the charge generation layer of the present invention generally vary depending on the composition, and the mechanical properties and solution viscosity vary depending on the degree of polymerization. In the present invention, since a polyvinyl butyral resin having an acetalization amount of 80 or more and an average molecular weight of 2000 or more is used as a binder of the charge generation layer, oxotitanium phthalocyanine which is a charge generation agent has good dispersion, and the charge transport described above. Since the solubility of the layer in the solvent used for the coating liquid is low, there is no trouble in applying the charge transport layer.

In the present invention, since tetrahydrofuran is used as the solvent for the charge generation layer, the solubility of the polyvinyl butyral resin is good, and the dispersion of oxotitanium phthalocyanine, which is the charge generation agent, is good. Further, the present invention contains 10 to 40 parts by weight of a hydrazone compound represented by the general formula ( Chemical Formula 2 ) and a butadiene compound represented by the general formula ( Chemical Formula 1 ) as a charge transporting agent. By utilizing the small charge leakage under high humidity, excellent electrophotographic characteristics can be obtained.

Since a polycarbonate resin is used as a binder for the charge transport layer, the compatibility between the charge transport agent and the binder resin is sufficient, and the ratio is optimal, so that the charge transport agent precipitates as crystals. There is no problem such as cleaning or cracking defects as a nucleus, and there is also a small part where the charging is uneven and the potential is not applied locally locally. In the case of development, it does not appear as black spots. Because the filling properties of the resin and charge transport agent are not bad,
Under high temperature and high humidity, the dark resistance of the photoreceptor decreases, and there is no problem such as a decrease in density in normal development and a fog in reversal development.

Further, there is a combination of an optimal charge transporting agent and an optimal carrier generating substance (charge generating agent). Since these are well matched, problems such as a decrease in charging ability, a decrease in sensitivity, and a deterioration in repetition characteristics are caused. Does not occur. As butadiene compound of the general formula (Formula 1), 1,1-bis -
A tetraphenylbutadiene compound such as 4,4-diphenyl1-1,3-butadiene, a styryl compound, and the like are considered. As the hydrazone compound of the general formula ( Chemical Formula 2), 2-methyl-4-dibenzylaminobenzaldehyde-1, 1
Phenylhydrazone compounds such as diphenylhydrazone are conceivable.

Hereinafter, the present invention will be described by way of examples.
In each of Examples and Comparative Examples, the coating method was dip coating, and the conductive support had an outer diameter of 30.
A mmΦ aluminum tube was used. Electrophotographic property evaluation
Trek's photosensitive drum evaluation system "ELYSIA-1"
(Registered trademark) ", and a printing evaluation was performed using a laser beam printer" Laser Shot-A408 "manufactured by Canon.
(Registered trademark) ".

[0029]

EXAMPLE 1 O-phthalodinitrile and titanium tetrachloride were used in a molar ratio of 3: 1 or 2.5: 1, and 5 to 10 times the amount of α-chloronaphthalene solvent was added thereto. It mixed and heated and stirred at 220-250 degreeC under nitrogen stream for 3 hours.
Thereafter, after allowing to cool to room temperature, the product was filtered, concentrated ammonia water was added to the product (dichlorotitanium phthalocyanine), and the mixture was heated under reflux for 1 hour to hydrolyze. Hydrolysis may be by hot water treatment. Washing liquid for hot water treatment is pH
It is necessary to repeat until 5-7.

The resulting titanium phthalocyanine was sufficiently washed with acetone using a Soxhlet extractor. The solvent methanol, may be used ethanol. Then, while maintaining the temperature at 5 ° C. or lower, 1 part by weight of oxotitanium phthalocyanine was dissolved in 10 parts by weight of concentrated sulfuric acid, followed by stirring for 2 hours. The sulfuric acid solution was stirred while being gradually dropped into 200 parts by weight of ice water to obtain a precipitate. This precipitate was sufficiently washed and purified with distilled water after filtration. FIG. 1 shows a differential heat pattern diagram showing the purity of the oxotitanium phthalocyanine thus obtained. Table 1 shows the results of infrared absorption spectrum, and FIG. 2 shows an X-ray diffraction diagram.

[0031]

[Table 1]

As shown in Table 1, the oxotitanium phthalocyanine used in the present invention has a wavelength of 775 cm ^-1 and 802 cm.
cm ^-1, 1160 cm ^-1, to show a weak absorption wavelength 966cm
It is characteristic that no absorption is observed at ^-1 and 1052 cm ^-1 .

Next, three kinds of adjusting liquids are prepared. 10 parts by weight of Elbamide (registered trademark, manufactured by DuPont) and 90 parts by weight of methanol were stirred at 40 ° C. for 7 hours to prepare an intermediate layer coating liquid. On the other hand, oxo titanium phthalocyanine 1.5 parts by weight butyral # 3000K (manufactured by Denki Kagaku)
1.5 parts by weight, THF (tetrahydrofuran) 97.0
Parts by weight were dispersed in an alumina ball mill for 48 hours to obtain a charge generation layer coating solution. Further, 4.5 parts by weight of 4-dibenzylamino-2-methylbenzaldehyde-1,1-diphenylhydrazone and 1,1-bis (p-diethylaminophenyl) -4,4-diphenyl-1,3 are used.
-4.5 parts by weight of butadiene, 14.0 parts by weight of polycarbonate Z (manufactured by Mitsubishi Gas Chemical), 35.0 parts by weight of toluene, and 42.0 parts by weight of methylene chloride were stirred at room temperature for 8 hours to form a charge transport layer. The coating solution was used.

Hereinafter, the coating process is performed in order. First, an outer diameter 30 of the above intermediate layer coating solution washed with a solvent.
It was coated on an aluminum tube of Φ by dip coating so that the coating amount when dried was 3 g / m ² . Further, a coating liquid for the charge generation layer was further applied thereon by a dip coating method so as to have a coating amount of 0.3 g / m ² when dried. Further, the above-mentioned coating solution for the charge transport layer was further applied with a coating amount of 35
g / m ² . The photoreceptor drum thus prepared was measured with "ELYSIA-I (registered trademark)" manufactured by Trek to obtain the following characteristic values. Initial charging -755V Dark decay retention (5 seconds) 90% Contrast potential 710V

Further, a print test was carried out using a laser beam printer (Laser Shot-A-408 (registered trademark)) manufactured by Canon Inc., and good print density was obtained.

Example 2 First, oxotitanium phthalocyanine is produced.
After 1,3-diiminoisoindoline is used as a solvent and α-chloronaphthalene is mixed, titanium tetraphthoxide is added, and the mixture is heated under a nitrogen atmosphere at 140 to 150 ° C. for 2 hours, and subsequently at 180 ° C. for 3 hours. Let react. After cooling to room temperature, the product is filtered. The produced titanium phthalocyanine is washed first with sulfolane, then with chloroform, further washed with a 2% hydrochloric acid aqueous solution, washed with water, and finally washed with methanol and dried. Then, as in Example 1, oxotitanium phthalocyanine is purified by sulfuric acid treatment. The charge generation layer coating liquid was applied to a 7 μm-thick alumite-treated aluminum tube having an outer diameter of 30Φ by a dip coating method so as to have a dry coating amount of 0.2 g / m ² . Further, a charge transport layer coating solution was applied thereon by the same dip coating method so that the coating amount upon drying was 30 g / m ² . The photoreceptor drum thus prepared was measured with "ELYSIA-I (registered trademark)" manufactured by Trek to obtain the following characteristic values. Initial charging -763V Dark decay retention (5 seconds) 94% Contrast potential 714V

Further, a print test was performed using a laser beam printer manufactured by Canon Inc. (Laser Shot-A-408 (registered trademark)), and good print density results were obtained. As described above, when the alumite processing is performed on the substrate, an insulating layer is formed, and the same function as that of the intermediate layer is obtained, and a good result is obtained.

Comparative Example 1 4-Dibenzylamino-2-methylbenzaldehyde
4.5 parts by weight of 1,1-diphenylhydrazone, 1,1
4.5 parts by weight of -bis (p-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene, 14.0 parts by weight of polycarbonate Z (manufactured by Mitsubishi Gas Chemical), and 77.0 parts by weight of methylene chloride at room temperature. For 8 hours to obtain a charge transport layer coating solution.

The intermediate layer coating solution shown in Example 1 was applied to a solvent-washed aluminum tube having an outer diameter of 30Φ by a dip coating method so as to have a coating amount of 3 g / m ² when dried. Furthermore, the coating liquid for the charge generation layer shown in Example 1 was further applied thereon by a dip coating method so as to have a coating amount of 0.3 g / m ² when dried. Further, the above-mentioned charge transport layer coating solution was applied thereon by the same dip coating method so that the coating amount upon drying was 30 g / m ² . The photoreceptor drum thus prepared is supplied to a laser beam printer (LaserSh manufactured by Canon Inc.).
ot-A @ 408 (registered trademark)), the result was a low density and extremely non-uniform overall. This is considered to be because only the methylene chloride was used as the solvent for the charge transport layer, and the charge generation layer was dissolved in the charge transport layer coating solution during the application of the charge transport layer.

Comparative Example 2 1.0 part by weight of oxotitanium phthalocyanine, 2.0 parts by weight of butyral, and 97.0 parts by weight of tetrahydrofuran produced by the method of Example 1 were dispersed in a ball mill for 48 hours. And A photoreceptor drum was prepared under the same conditions except that the coating solution for the charge generation layer in Example 1 was replaced with this coating solution. The photoreceptor drum thus prepared was measured with "ELYSIA @ I (registered trademark)" manufactured by Trek to obtain the following characteristic values. Initial charging −761 V Dark decay holding ratio (5 seconds) 94% Contrast potential 659 V As described above, in Comparative Example 2, the contrast potential was low, and the print density was low as a result of the print test, and the print was slightly faint. Was.

Comparative Example 3 A charge transport layer was coated at a dry amount of 15 g / m ² ,
An electrophotographic photosensitive member was obtained in the same manner as in Example 1. Using this electrophotographic photoreceptor, the characteristics of the electrophotographic photoreceptor were examined in the same manner as in Example 1. When printing was performed, the initial charging potential was low. Was.

Comparative Example 4 The same procedure as in Example 1 was carried out except that the dry coating amount of the charge transport layer was 50 g.
An electrophotographic photoreceptor was obtained in the same manner as in Example 1, except that / m ² was used. Using this electrophotographic photoreceptor, the characteristics were examined and printing was performed in the same manner as in Example 1. When the printing was performed, the initial charging potential was sufficiently high, but the contrast potential was low.
In the actual print test, the print density was low overall.

[0043]

As described above, in the electrophotographic photoreceptor of the present invention, in each of the charge generating layer and the charge transporting layer, the combination of the charge generating agent, the charge transporting agent, the binder resin, and the solvent is appropriate. In addition, the combination of the respective layers can provide an electrophotographic photosensitive member having good compatibility with the resin, good sensitivity, and excellent quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing a differential heat pattern of oxotitanium phthalocyanine according to the present invention.

FIG. 2 is an X-ray diffraction diagram of oxotitanium phthalocyanine according to the present invention.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI G03G 5/05 101 G03G 5/05 101 102 102 5/10 5/10 B (56) References JP-A-4-97159 (JP) JP-A-3-50554 (JP, A) JP-A-3-9962 (JP, A) JP-A-2-173655 (JP, A) JP-A-1-207755 (JP, A) JP-A-5-173345 (JP, A) JP-A-5-257309 (JP, A) JP-A-2-73360 (JP, A) JP-A-4-104258 (JP, A) JP-A-4-257866 (JP, A A) JP-A-3-157666 (JP, A) JP-A-63-55553 (JP, A) JP-A-63-267949 (JP, A) JP-A-2-256057 (JP, A) JP-A-5 JP-A-289380 (JP, A) JP-A-4-30171 (JP, A) JP-A-3-50555 (JP, A) JP-A-3- 166548 (JP, A) JP-A-5-216250 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 5/00

Claims (2)

(57) [Claims] To 1. A conductive substrate, in (X) infrared absorption spectrum, 729cm ^-1, 752cm ^-1, 894c
m ⁻¹ , 971 cm ⁻¹ , 1070 cm ⁻¹ , 1119 cm ⁻¹ , 13
It has a strong absorption to 33cm ^-1, also 775cm ^-1, 802cm
^-1, 8 79cm ^-1, has a weak absorption in the 1 1 60cm ^-1,
(Y) Bragg angle (2 ° ± 0.2 °) in X-ray diffraction spectrum for CuKα ray (wavelength 1.541 °)
7.5, 10.2, 12.5, 16.3, 22.4, 2
Α-type oxotitanium phthalocyanine crystal composition 30 having a strong diffraction peak at 4.2, 25.3, 28.6 degrees
-70 parts by weight, acetalization amount of 80 or more, average degree of polymerization of 2
Charge generating layer formed by a charge generating agent containing 30 to 70 parts by weight of polyvinyl butyral resin of 000 or more
When 10 to 40 parts by weight of diphenyl hydrazone compound represented by the following general formula (Formula 1) tetraphenylbutadiene compounds 10 to 40 parts by weight represented by the following general formula (Formula 2), a further polycarbonate resin 40 A charge transport layer formed by a charge transport agent containing 70 parts by weight,
In the electrophotographic photoreceptor provided with
Tetrahydrofuran (TH
F) using a solvent for the coating solution for the charge transport layer
And using a mixed solution of toluene and methylene chloride . Embedded image (In the formula, R ₁ represents a di-lower alkylamino group, and R ₂ represents a hydrogen atom or a di-lower alkylamino group.) (Wherein, R ₃ and R ₄ represent the same or different lower alkyl groups, benzyl groups and substituted or unsubstituted phenyl groups, and R ₅ represents a hydrogen atom, a lower alkyl group, a lower alkoxy group and a benzyloxy group. ) 2. The electrophotographic photoreceptor according to claim 1, wherein aluminum is used as the conductive support and the surface thereof is anodized.