JPH09281719A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoreceptor superior in performance to digital light input and repetion characteristics and long in life and high in stability by using a polycarbonate as a binder resin and a compound having a hydroxy group in a photosensitive layer. SOLUTION: This electrophotographic photoreceptor is obtained by forming a photosensitive layer having the titanylphthalocyanine dispersed into the binder resin on a conductive substrate, and this binder resin is made of the polycarbonate resin and contains the compound having a hydroxy group. The titanylphthalocyanine to be used can be embodied by the amorphous one, and the crystalline one having the strong diffraction peak at an angle of 27.3 deg., and the like. The polycarbonate resin to be used is not especially limited so far as having a number average molecular weight of 3,000-500,000, preferably, 10,000-200,000, and a structure represented by the formula in which R is an organic divalent bonding group and (n) is a natural number.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to electrophotography.
For electrophotographic photoreceptors suitable for used digital electrophotography
It is about. For details, see the threshold in the light decay curve.
And an exposure energy that causes a transition from a high surface potential to a low surface potential.
Electrophotographic photoreceptor with small energy change (high γ value photoreceptor)
It is about. In addition, in the present invention, "light attenuation
Having a threshold on the curve "means that
Shall mean. That is, in the light decay curve,
The initial potential after is V₀ (V), residual potential of 50 μJ /
cm ^TwoThe surface potential when the light of_r(V)
The difference between the two is ΔV (V₀-V_r). This time,
"95% surface potential" V₉₅As the residual potential ΔV of 95
Surface potential (V₉₅= ΔV × 0.95 + V
r), "5% surface potential" V_FiveAs the residual potential
Surface potential (V_Five= ΔV × 0.0
5 + V_r), V₉₅, V_FiveExposure energy that gives
"95% exposure energy" E₉₅, "5% exposure
Energy "E_FiveAs E,_Five/ E₉₅Is less than 5
It means that there is.

[0002]

2. Description of the Related Art Electrophotographic methods such as the Carlson method have been developed with a focus on rendering an original image in an analog manner. Therefore, in order to faithfully reproduce the brightness of the input light as the brightness of the toner image, the photoconductor used therein may have a characteristic that a photocurrent flows linearly similar to (the logarithmic value of) the input light amount. I have been asked. Therefore, it has been a principle to select a photosensitizer having such characteristics (low γ characteristics) as a material for the photoconductor. Therefore, it should be similar to the photosensitive layer in the amorphous state of selenium (Se) system, the amorphous layer of silicon (Si), and the amorphous layer of Se, starting from those close to simple photoconductors in the initial stage of electrophotography. The prepared ZnO tie layer or the like has been used as a photoreceptor.
Furthermore, in recent years, a so-called function-separated type photosensitive layer using an organic semiconductor has been developed until it is used as a photoconductor. However, in recent years, the electrophotographic technology and the computer / communication have been combined, and the printer and facsimile systems have rapidly changed to the electrophotographic recording system. It is becoming a method that enables image processing. for that reason,
It is desired to change the recording method of electrophotography from the conventional analog recording format for PPC to the digital recording format.

Further, as an input light source used in the digital recording system, there are a gas laser such as an Ar laser and a He-Ne laser, a semiconductor laser, a shutter array such as a liquid crystal, an LED and an EL array. Among them, semiconductor lasers are currently the mainstream because they can be downsized and reduced in cost, and a photosensitizer having high sensitivity in the near infrared region, which is the oscillation wavelength of semiconductor lasers, is required.

Further, as described above, the photoconductor used in the traditional electrophotographic method based on the analog concept is
It has a low γ characteristic, and due to its characteristics, it is suitable for electronic photography, such as a printer for outputting data from a computer, or a digital copy for digitally processing an image, in which an input digital optical signal must be rendered as a digital image. Not suitable. That is, even the deterioration of the digital signal in the signal path from the computer or image processing device to the electrophotographic device, or the aberration caused by the optical system for converging the writing light beam or forming the original image. However, the photoconductors using these photosensitizers faithfully depict the original digital images.
Therefore, it is strongly desired to provide a digital photoconductor having high sensitivity and high γ characteristics which can be used in this field.

[0005]

Under these circumstances, Japanese Patent Laid-Open No.
No. 169454 discloses the concept of a digital photoconductor. However, no specific mention is made of materials that can be used for this digital photoconductor.
The present invention has been made in view of the present situation, and has excellent performance (high γ characteristic) for digital optical input, and
It is an object of the present invention to provide a photoreceptor having excellent repeatability, long life and high stability.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to solve the above-mentioned problems, and as a result, have found that a photosensitive material containing a phthalocyanine and a polycarbonate resin dispersed therein contains a compound having a hydroxyl group. The present invention has been completed by finding that the body is a digital photoreceptor having excellent performance (high γ characteristic) with respect to digital light input and excellent repeatability and having a long life and high stability.

That is, according to the present invention, in an electrophotographic photoreceptor having a photosensitive layer having a titanyl phthalocyanine dispersed in a binder resin provided on a conductive substrate, a polycarbonate resin is used as the binder resin, and a hydroxyl group is contained in the photosensitive layer. An electrophotographic photoreceptor comprising a compound having:
In particular, it is an electrophotographic photosensitive member (high γ value photosensitive member) that has a threshold value in the light attenuation curve and has a small change in exposure energy that causes a transition from a high surface potential to a low surface potential.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. (1) Titanyl phthalocyanine Various crystal forms of titanyl phthalocyanine have been known so far, but the titanyl phthalocyanine used in the present invention is not particularly limited. For example, an amorphous form, usually an X-ray diffraction spectrum using CuKα ray Bragg angles (2θ ± 0.2 °) of 7.6 °, 25.3 °, 2
Α form having a main peak at 8.6 °, usually Bragg angle (2θ ± 0.2 °) 9.3 °, 13.3 °, 26.3
Β-type with a major peak at °, usually Bragg angle (2
θ ± 0.2 °) 7.0 °, 15.6 °, 23.4 °, 2
C-type having a main peak at 5.5 °, usually Bragg angle (2θ ± 0.2 °) 9.5 °, 24.1 °, 27.3
A crystal form having a peak at 0 °, of which the intensity of the diffraction peak at 27.3 ° is the strongest, may be mentioned. Among them, amorphous type, β type and Bragg angle (2θ ± 0.2 °)
The crystal form showing peaks at 9.5 °, 24.1 °, and 27.3 °, of which the intensity of the diffraction peak at 27.3 ° is the strongest, the crystal form is preferable, and further, in the X-ray diffraction spectrum, the Bragg angle (2θ ± 0 .2 °) 9.5 °, 24.1 °, 27.3
Usually, a crystalline form of titanyl phthalocyanine having a peak at 2 °, of which the diffraction peak at 27.3 ° has the highest intensity, is most preferable.

The method for synthesizing titanyl phthalocyanine is described in Moser and Thomas's "phthalocyanine compound" (MO
SER and THOMAS, “Phthalocy”
anine Compounds ") known method, etc., for example, a method in which o-phthalonitrile and titanium tetrachloride are melted by heating or heated in the presence of an organic solvent such as α-chloronaphthalene, 1,3- It can be obtained in good yield by heating diiminoisoindoline and tetrabutoxytitanium with an organic solvent such as N-methylpyrrolidone etc. The titanyl phthalocyanine thus synthesized may contain a chlorine-substituted phthalocyanine. As a method for producing titanyl phthalocyanine having the highest intensity of the diffraction peak at 27.3 ° described above, for example, titanyl phthalocyanine is mechanically ground and treated by adding water and an organic solvent. 289
No. 658, etc., but the invention is not limited to this method. For example, even if it can be manufactured by another manufacturing method, it includes as long as it belongs to the same crystal form crystallographically. Is.

(2) Polycarbonate Resin The polycarbonate resin used in the present invention is not particularly limited as long as it has a structure represented by the following general formula.

[0011]

Embedded image

In the above general formula, R represents a divalent organic residue, and n represents a natural number. The method for producing the polycarbonate resin used in the present invention includes a method in which an aromatic dihydroxy compound and a carbonic acid derivative are polymerized by transesterification (ester exchange method, melt polymerization method), and an aromatic dihydroxy compound and phosgene as a deoxidizing agent. There are a method of polymerizing in a solution in the presence or at an interface (phosgene method), a method of ring-opening polymerization of a cyclic oligocarbonate, and the like.

The method for producing the polycarbonate resin used in the present invention by the phosgene method (interfacial polymerization method) uses methylene chloride, toluene and xylene as organic solvents, uses an aqueous alkaline solution as a deoxidizing agent, and uses dihydroxy. Polymerization is carried out by coexisting an organic solvent in an aqueous alkaline solution of the compound and blowing phosgene into the organic solvent. Phosgene is usually blown in an excess of about 20%. Also,
Tertiary amine, quaternary ammonium, phosphonium salts, etc. may be added to accelerate the polymerization reaction. The reaction temperature is 0 to 50 ° C, preferably 10 to 30 ° C. The reaction time varies depending on conditions such as temperature and catalyst, but is 30 minutes to 5 hours.

In the method for producing the polycarbonate resin used in the present invention by the transesterification method, an aromatic dihydroxy compound and an aromatic ester of carbonic acid are melt-polymerized in the presence of a base catalyst. As a catalyst for transesterification, basic metal oxides such as alkali metals, alkaline earth metals and zinc oxide, carbonates of various metals, acetates, hydrides, quaternary ammonium salts, phosphonium salts and other basic metals Salt is used. Polymerization is carried out by gradually reducing the pressure between 200 and 350 ° C. Eventually 1mmH
The reaction is terminated by adjusting the pressure to a high pressure of g or less. The reaction time varies depending on conditions such as temperature and catalyst, but it is 2 to 5 hours. Further, during polymerization, it should be carried out in an inert atmosphere of nitrogen, argon or the like in order to suppress abnormal reactions such as decomposition and crosslinking.

The polycarbonate resin used as the binder resin in the present invention has a number average molecular weight of 3,000 to 5,000.
00 is preferable, and those of 10,000 to 200,000 are more preferable. The glass transition temperature is 20 to 3
The temperature is 00 ° C, more preferably 50 to 250 ° C. Such a polycarbonate resin may be obtained by polymerizing each of the above monomers by the above method, but a commercially available product may be used.
Examples of commercially available products include "Upilon" (particularly Z-200) manufactured by Mitsubishi Gas Chemical Co., Inc., "APEC" manufactured by Bayer Japan Co., Ltd., and the like. In the present invention, it is preferable to use substantially only the polycarbonate resin as the binder resin, but other resins may be mixed depending on the case.

(3) Compound Having Hydroxyl Group The compound having a hydroxyl group of the present invention is not particularly limited as long as it contains a hydroxyl group, but it is a compound having an aromatic hydroxyl group having 6 to 30 carbon atoms and 6 to 20 carbon atoms. Compounds having an aliphatic hydroxyl group are preferred. Further, a compound having 6 to 25 carbon atoms and having an aromatic hydroxyl group, and a compound having 6 to 15 carbon atoms and having an aliphatic hydroxyl group are preferable. Among the above compounds,
It is more preferable that an electron withdrawing group such as a halogen atom or a nitro group or an ester group is contained as a substituent.
These hydroxyl group-containing compounds are, for example, phenol, fluorinated phenol, chlorophenol, brominated phenol (the number of these halogen atoms is 1 to 5), trifluoromethylphenol, trichloromethylphenol in the aromatic system,
Nitrophenol (number of nitro groups 1-5), cyanophenol (number of cyano groups 1-5), aminophenol (number of amino groups 1-5), methylphenol (number of methyl groups 1-5), t- Butylphenol (Number of t-butyl groups 1
~ 3), methoxyphenol (number of methoxy groups 1 ~
3), hydroxybenzaldehyde, hydroxyacetophenone, salicylic acid, benzyl alcohol, chlorobenzyl alcohol, bromobenzyl alcohol, fluorobenzyl alcohol, methyl hydroxybenzoate, phenylphenol (the number of phenyl groups is 1 to 1).
3), phenylazophenol, hydroxynaphthophenone, hydroxynaphthalene, dihydroxynaphthalene, bisphenol A, bisphenol F, tetrabromobisphenol A, tetrabromobisphenol A-bishydroxyethyl ether and the like.

In the aliphatic system, chlorohexanol, bromohexanol, fluorohexanol, chlorocyclohexanol, heptanol, chloroheptanol, octanol, nonanol, trimethylhexanol, decanol, eicosanol, heptanediol, octanediol, nonanediol, decanediol, Eicosane diol etc. are mentioned. The addition rate of the compound containing a hydroxyl group is 0.001 to 2 with respect to the total weight of titanyl phthalocyanine and the polycarbonate as the binder resin.
It is 0 wt%, preferably 0.001 to 10 wt%, and more preferably 0.001 to 5 wt%.

(4) Electrophotographic Photoreceptor In the electrophotographic photoreceptor of the present invention, a photosensitive layer in which the above-mentioned titanyl phthalocyanine and the above-mentioned compound having a hydroxyl group are dispersed in the above-mentioned polycarbonate resin is provided on a conductive substrate. Is obtained by That is, a compound having a titanyl phthalocyanine and a hydroxyl group and a polycarbonate resin are uniformly dispersed with a solvent and the like in a kneading disperser such as a ball mill and an attritor, and coated on a conductive support to form a single photosensitive layer. Just do it.

That is, the weight ratio of titanyl phthalocyanine and the polycarbonate resin to the phthalocyanine of the polycarbonate resin is set to about 1 to 10, and 0.001 to 20 of the compound containing a hydroxyl group is added to the weight.
Add wt% and mix with solvent. Then, the mixed dispersion liquid is applied to a metal such as aluminum ordinarily used for an electrophotographic photosensitive member, or a conductive support such as paper or plastic subjected to conductive treatment to form a photosensitive layer.

The solvent used for the coating liquid is preferably selected from those which dissolve the above polycarbonate resin and do not cause the growth of crystals of titanyl phthalocyanine which hinders the performance. Examples of the solvent having such a property include: Hydrocarbons such as toluene, xylene, mineral spirits, ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, cyclohexanone, halogenated hydrocarbons such as dichloromethane, dichloroethane, trichloroethane, chlorobenzene, tetrahydrofuran, dioxane, monoglyme, diglyme, anisole Ethers such as, methanol, ethanol, propanol,
Examples include alcohols such as butanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cyclohexanol, esters such as ethyl acetate, propyl acetate and butyl acetate, amides such as dimethylformamide and N-methylpyrrolidone. it can. These solvents may be used alone or in combination of two or more.

As a coating method, if necessary, a solvent such as toluene or cyclohexanone is added to the above mixture to adjust the viscosity, and then an air doctor coater, a plate coater,
Dip coater, ring coater, rod coater,
The film is formed by a coating method such as a reverse coater, a spray coater, a hot coater, a squeeze coater, a gravure coater. After coating, it is dried until a sufficient charging potential is imparted as a photoconductive layer. Drying is carried out at a temperature of 30 to 300 ° C. after preliminary drying at room temperature
It is performed in the range of minutes to 24 hours.

The electrophotographic photosensitive member (hereinafter, referred to as the photosensitive member of the present invention) manufactured by the above means according to the present invention usually has a resin / photoconductive material ratio of 1 or more by weight. Therefore, for example, the amount of resin is larger than in the case of the conventional photoconductor using zinc oxide in which the weight ratio of resin / photoconductive material is 0.2. Therefore, there is a physical strength of the coating,
It is possible to realize a flexible photoconductor.

Further, for the purpose of improving various characteristics of the photoreceptor, it is possible to provide an undercoat layer between the conductive substrate and the photosensitive layer and an overcoat layer on the photosensitive layer. Further, additives such as antioxidants may be added for the purpose of improving stability and the like. The thickness of the photosensitive layer thus obtained is 5
The range is preferably from 50 to 50 μm, more preferably from 10 to 30 μm.

The photoconductor of the present invention produced as described above has a large adhesiveness with a conductive support, good moisture resistance, little change over time, little toxicity problems, and is not easily produced. It has practically excellent characteristics such as easy and inexpensive. The photoconductor of the present invention obtained as described above is usually used by positive charging, and as a photoconductor for digital light input in order to cause a specific photocurrent flow compared with the case of the conventional photoconductor. Can be used.

That is, in the conventional photoconductor, as described above, the photocurrent of an amount linearly corresponding to (the logarithmic value of) the input light amount flows, whereas the photoconductor of the present invention has a certain input. The photocurrent does not flow up to the light amount, or it is a very small amount,
It has a threshold value in a light attenuation curve in which a photocurrent suddenly flows out immediately after the light amount is exceeded (see FIG. 4).

In digital recording, image gradation is expressed by the dot area, and therefore the photosensitivity characteristics of the photoconductor used in this recording method are preferably those described above. This is because, even if the laser spot is accurately modulated by the optical system, the distribution of the light quantity of the spot itself and the halo cannot be avoided in principle. Therefore, in the conventional photoconductor, which changes the light energy (input light amount) stepwise, the dot pattern changes due to the light amount change, which causes fog as noise. Therefore, the photoconductor of the present invention is a photoconductor advantageous as a photoconductor for digital light input.

[0027]

The present invention will be described below with reference to examples. <Production Example of Titanyl Phthalocyanine> Production Example 1 58 g of 1,3-diiminoisoindoline and 51 g of tetrabutoxytitanium were reacted in 300 ml of α-chloronaphthalene at 210 ° C. for 5 hours, and then heat filtered at 150 ° C. to obtain α-
Chloronaphthalene and dimethylformamide (DMF) were washed in this order. Then, it was washed with hot DMF, hot water and methanol and dried to obtain 51 g of titanyl phthalocyanine. An X-ray diagram of this titanyl phthalocyanine is shown in FIG. Bragg angle (2θ ± 0.2 °) 9.3 °, 13.2
This is β-type titanyl phthalocyanine having a peak at 2 ° and 26.2 °.

Production Example 2 4 g of the titanyl phthalocyanine produced in Production Example 1 was dissolved in 400 g of sulfuric acid at 0 ° C., and this acid solution was added dropwise to 4 L of water cooled to 0 ° C. After completion of dropping, the mixture was stirred for 1 hour, filtered, and washed with water until the filtrate became neutral to obtain 3.1 g of titanyl phthalocyanine. The X-ray diagram of this titanyl phthalocyanine is shown in FIG. It is an amorphous form that does not have a particularly sharp peak.

Production Example 3 6 g of the titanyl phthalocyanine produced in Production Example 1 and 50 g of glass beads were placed in a 100 ml poly bottle and ground in a paint shaker (Red Devil) for 40 hours. Then, the titanyl phthalocyanine was separated from the glass beads with methanol, and the obtained titanyl phthalocyanine was washed with 100 ml of water. This titanyl phthalocyanine wet cake was added to a mixed solution of 100 ml of water and 10 ml of dichlorobenzene, stirred for 1 hour, filtered and washed with methanol to obtain 4.3 g of titanyl phthalocyanine. An X-ray diagram of this titanyl phthalocyanine is shown in FIG. Bragg angle (2θ ± 0.2 °) 9.5 °, 24.1
Has peaks at 2 ° and 27.3 °, of which the intensity of the diffraction peak at 27.3 ° is the strongest.

<Production Example of Polycarbonate Resin> Production Example 4 A 2 L flask equipped with a stirrer, a reflux condenser, a thermometer, a gas introduction tube, a pH electrode and a dropping funnel was replaced with nitrogen, and then 1,1-bis (4 -Hydroxyphenyl) -cyclohexane (147.4 g, 0.55 mol), sodium hydrogen sulfite (0.11 g), aqueous sodium hydroxide solution (NaOH: 55 g, 1.38 mol, water: 600 m)
1) and methylene chloride (400 ml) were added. The reaction temperature was maintained at 23 to 27 ° C., and phosgene was bubbled in under vigorous stirring until the pH of the reaction solution dropped to 7. The time required for the reaction was about 2 hours. About 70 g of phosgene was used. Next, sodium hydroxide aqueous solution (NaOH: 3
0 g, water: 30 ml) and benzyltriethylammonium chloride (4.8 g) were added, and the mixture was vigorously stirred at 25 to 35 ° C for 1 hour. After the reaction was completed, the organic phase was separated from the aqueous phase, and the organic phase was washed with water (500 ml) three times. 2% HC
It was washed with an aqueous solution (500 ml) and water (500 ml). After washing, put into methanol, separate by filtration, and then under reduced pressure 1
It was dried at 00 ° C. for 10 hours.

Production Example 5 1,1-bis (4-hydroxyphenyl) -of Production Example 4
Cyclohexane (147.4 g, 0.55 mol) was added to 1,
1-Bis (4-hydroxyphenyl) -cyclohexane (73.7 g, 0.275 mol) and bisphenol A
(62.5 g, 0.275 mol) and was polymerized in the same manner as in Production Example 4.

Production Example 6 1,1-bis (4-hydroxyphenyl) -of Production Example 4
Cyclohexane (147.4 g, 0.55 mol) was added to 1,
1-bis (4-hydroxyphenyl) -cyclohexane (73.7 g, 0.275 mol) and bisphenol F
(55 g, 0.275 mol) and was polymerized in the same manner as in Production Example 4.

Production Example 7 1,1-bis (4-hydroxyphenyl) -of Production Example 4
Cyclohexane (147.4 g, 0.55 mol) was added to 1,
1-Bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (170.5 g, 0.275 mol) and bisphenol A (62.5 g, 0.275 mol) were used, and the same as in Production Example 4. Polymerized.

Production Example 8 1,1-bis (4-hydroxyphenyl) -of Production Example 4
Cyclohexane (147.4 g, 0.55 mol) was added to 1,
1-bis (4-hydroxyphenyl) -cyclohexane (73.7 g, 0.275 mol) and 1,1-bis (4-
Hydroxyphenyl) -phenyl-ethane (79.8)
g, 0.275 mol) and polymerized in the same manner as in Production Example 4. Next, examples of the electrophotographic photoreceptor of the present invention using the titanyl phthalocyanine and the polycarbonate resin obtained in each production example, and the compound having a hydroxyl group will be described.

Example 1 0.25 g of the titanyl phthalocyanine obtained in Production Example 1
And 12.5 mg (1 wt%) of bromophenol were sealed in a glass container together with 1.0 g of the polycarbonate resin obtained in Production Example 4, 6.5 g of toluene, and 12 g of glass beads (diameter 2 mm), and a paint shaker (red devil). (Manufactured by K.K.) for 4 hours, and the glass beads were separated after dispersion to obtain a photoreceptor coating liquid. This photoconductor coating solution was applied on a degreased aluminum sheet having a thickness of 90 μm by a wire bar method, preliminarily dried at room temperature, and then dried in an oven at 100 ° C. for 1 hour to give a photoconductor film thickness of 18 μm.
m photoconductor was obtained.

Examples 2 to 41 Titanyl phthalocyanine (TiO 2) shown in Table 1 below.
A photoconductor was obtained in the same manner as in Example 1 by using 0.25 g of Pc), a hydroxyl group-containing compound, and 1.0 g of a polycarbonate resin (PCR).

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

Comparative examples used to evaluate the hydroxyl compound according to each example of the present invention will be described below. Comparative Example 1 0.25 g of titanyl phthalocyanine obtained in Production Example 1
To the polycarbonate resin 1.0 obtained in Production Example 4.
g, toluene 6.5 g, glass beads (diameter 2 mm) 1
It was sealed together with 2 g in a glass container and dispersed for 4 hours with a paint shaker (manufactured by Red Devil Co.), and after dispersion, glass beads were separated to obtain a photoreceptor coating solution. This photoconductor coating solution is applied on a degreased aluminum sheet having a thickness of 90 μm by a wire bar method, preliminarily dried at room temperature, and then dried in an oven at 100 ° C. for 1 hour to form a photosensitive layer having a thickness of 1
An 8 μm photosensitive member was obtained.

Comparative Examples 2 to 9 Titanyl phthalocyanine (TiO 2) shown in Table 2 below.
Pc) 0.25 g, polycarbonate resin (PCR)
A photosensitive member was obtained in the same manner as in Comparative Example 1 using 1.0 g. In Comparative Example 9, pentabromotoluene was used instead of the hydroxyl group-containing compound.

[0042]

[Table 4]

<Evaluation of Electrophotographic Photoreceptor> The photosensitivity of each of the photoreceptors of Examples and Comparative Examples obtained above was evaluated by a photoreceptor evaluation apparatus (Cynthia-55, manufactured by Gentec).
Was evaluated using First, corona charging was performed at a voltage of +6.0 KV, and monochromatic light of 780 nm with different light intensity was applied to each corona-charged photoconductor, and the light decay time curve for each light intensity (characteristic curve of surface potential against irradiation time) )
Was measured respectively. Then, the surface potential after irradiation for a certain period of time (here, 0.075 seconds) obtained from the curve was plotted against the light energy. This is called a light attenuation curve, and an example is shown in FIG.

The light energy capable of maintaining the surface potential at about the same level as the initial potential V ₀ immediately after charging (95% surface potential) is E ₉₅ (light energy at the falling point in the light attenuation curve), and the surface potential is 50 μJ / cm 2. ² Residual potential V after irradiation
_The light energy that can be reduced to about _r (5% surface potential) is E ₅ (light energy at the rising point of the light attenuation curve), and the value of E ₅ / E ₉₅ can be digitally recorded according to the following evaluation criteria. I was aiming.

0 <E ₅ / E ₉₅ ≦ 5: Digital recording is possible 5 <E ₉₅ / E ₅ : Analog recording Further, among 0 <E ₅ / E ₉₅ ≦ 5, the smaller E ₉₅ is, the light sensitivity is higher. It can be said that it is excellent as an electrophotographic photoreceptor. Table 3 shows the evaluation results.

[0046]

[Table 5]

[0047]

[Table 6]

[0048]

[Table 7]

[0049]

As described above, the photoconductor obtained by dispersing the compound having titanyl phthalocyanine and the hydroxyl group of the present invention in the polycarbonate resin has a peculiar flow of optical power to the light input, that is, an analog light. It can be output as a digital signal regardless of whether it is present or digital light. Therefore, it can be used for a digital recording type electrophotography, and can realize a high-quality image with a sharp edge even when used for a conventional PPC (analog light input) photoconductor.

[Brief description of drawings]

FIG. 1 is an X-ray diagram of titanyl phthalocyanine obtained in Production Example 1.

FIG. 2 is an X-ray diagram of titanyl phthalocyanine obtained in Production Example 2.

FIG. 3 is an X-ray diagram of titanyl phthalocyanine obtained in Production Example 3.

FIG. 4 is a diagram showing an example of an optical attenuation curve.

Claims (5)

[Claims] 1. An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer having titanyl phthalocyanine dispersed in a binder resin, wherein a polycarbonate resin is used as the binder resin, and a hydroxyl group is contained in the binder resin. An electrophotographic photoreceptor containing a compound. 2. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member has a threshold value in its light decay curve and is for digital light input. 3. The compound having a hydroxyl group has 6 carbon atoms.
To 30 aromatic hydroxyl group-containing compound, 6 to 2 carbon atoms
The electrophotographic photosensitive member according to claim 1 or 2, which is a compound having an aliphatic hydroxyl group of 0. 4. The content of the compound having a hydroxyl group is
The electrophotographic photoreceptor according to claim 1, wherein the content of the solid content in the photoreceptor is 0.001 to 20 wt%. 5. The X-ray diffraction spectrum of the titanyl phthalocyanine has a Bragg angle (2θ ± 0.2 °).
Showing peaks at 9.5 °, 24.1 ° and 27.3 °,
The electrophotographic photosensitive member according to any one of claims 1 to 4, which is a crystalline form of titanyl phthalocyanine having the highest intensity of the diffraction peak at 27.3 °.