JP4330592B2 - Electrophotographic photosensitive member and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming apparatus, and more particularly, to an electrophotographic photosensitive member capable of effectively suppressing generation of exposure memory and an image forming apparatus using the same.

In general, organic photoconductors are often used as electrophotographic photoconductors used in electrophotographic machines such as copying machines and laser printers due to demands for low cost and low environmental pollution.
In addition, the surface of such an organic photoreceptor is charged (main charging step) and an electrostatic latent image is formed (exposure step), and then the electrostatic latent image is applied with a developing bias voltage. An image forming process is performed in which toner development (development process) is performed, and the formed toner image is transferred to transfer paper by a reversal development method (transfer process), which is heated and fixed to form a predetermined image. ing.
The residual toner on the organic photoconductor is removed using a cleaning blade (cleaning step), and the residual charge on the organic photoconductor is erased by an LED or the like (static elimination step). .

However, in such an organic photoreceptor, since the organic photoreceptor is rotated and used, the potential (bright potential) of the portion exposed in the previous round remains and the charging process in the next round is performed. In such a portion, a phenomenon (exposure memory) in which a desired charging potential (dark potential) cannot be obtained was observed.
For this reason, there has been a problem that the image density is changed between the portion with and without the exposure memory, and a good image cannot be obtained.

Therefore, in order to provide an electrophotographic photoreceptor with little potential fluctuation even when used repeatedly, in the negatively charged laminated organic photoreceptor, a substance used as a charge transport agent is specified, and the charge transport layer and the charge An electrophotographic photoreceptor in which the difference in ionization potential between the generation layers is defined is disclosed (for example, Patent Document 1).
JP-A-7-36204 (Claims)

However, the electrophotographic photosensitive member disclosed in Patent Document 1 is limited to a negatively charged laminated type organic photosensitive member, and there is a problem that the exposure memory cannot be suppressed yet for other photosensitive type. It was. In particular, in the case of a photoconductor having a long electron transport distance such as a positively charged single layer type photoconductor, there has been a problem that exposure memory is remarkably generated.
Further, in an image forming apparatus equipped with the above-described positively charged single layer type photoreceptor and having no charge eliminating means, the occurrence of exposure memory is more remarkable.
In addition, as a factor that the electron transport distance in the positively charged single layer type photoreceptor affects the exposure memory, an electron transport agent having mobility as high as a hole transport agent has not been developed yet, and In comparison, the single layer type photoreceptor has lower charge transport efficiency.
In addition, as described above, development of a technique for suppressing the occurrence of exposure memory is required, but it is also necessary to meet the demand for higher speed in the image forming apparatus. For this reason, the electrophotographic photoreceptor needs to be highly sensitive to exposure.

Therefore, the inventors of the present invention, as a result of intensive studies, in the single-layer type photoreceptor, the reflection absorbance, film thickness, etc. in the photosensitive layer satisfy a predetermined relationship, and the type of charge generator used and It has been found that by limiting the characteristics of the hole transport agent, not only the exposure memory can be suppressed, but also the sensitivity can be improved.
That is, an object of the present invention is to provide a single-layer electrophotographic photosensitive member that can effectively suppress exposure memory and has high sensitivity, and an image forming apparatus using the same.

According to the present invention, in an electrophotographic photoreceptor having a single-layer type photosensitive layer containing at least a charge generator, a hole transport agent, an electron transport agent, and a binder resin on a substrate, charge generation is performed. As the agent, an oxotitanyl phthalocyanine crystal having a Y-type crystal structure and having the following characteristic (b) is used, and the concentration (C / wt%) of the oxo titanyl phthalocyanine crystal in the single-layer type photosensitive layer is 0.6 to 3%. The mobility measured at a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm is 5.0 × 10 5. ^{−6 to} 5.0 × 10 ⁻⁴ cm ² / V / sec, a hole transport agent having a value in the range, and the reflection absorbance (A / −) with respect to light having a wavelength of 700 nm in the photosensitive layer; Film thickness (d / m) in the layer and in the photosensitive layer Concentration of Kiso titanyl phthalocyanine crystals (C / wt%), but the electrophotographic photosensitive member that satisfies the following equation (1).
Can be provided to solve the above-mentioned problems.
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it does not have a peak in the range of 50 to 200 ° C, but has one peak in the range of 296 to 400 ° C. When the layer satisfies the characteristic represented by the relational expression (1), the dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer can be improved, so that the exposure memory is effectively suppressed. Can do.
In addition, by setting the mobility of the hole transport agent to be used to a value within a predetermined range, it is possible to efficiently transport holes generated from the charge generating agent and more effectively suppress the exposure memory. it can.
Furthermore, as the exposure memory described above can be suppressed, the movement of charges in the photosensitive layer can be performed efficiently, so that the sensitivity during exposure can also be improved.

In constituting the electrophotographic photosensitive member of the present invention, the charge generator is preferably an oxotitanyl phthalocyanine crystal having a Y-type crystal structure.
With such a configuration, it becomes easy to satisfy the relational expression (1), and it is possible to provide an electrophotographic photosensitive member having a high sensitivity while reducing the occurrence of exposure memory.

In constituting the electrophotographic photoreceptor of the present invention, an oxo titanyl phthalocyanine crystal having the following characteristics (b) is contained as a charge generator .
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it has no peak in the range of 50 ° C. to 200 ° C. and one peak in the range of 296 to 400 ° C. By constituting in this manner, the stability with time and dispersibility of the oxotitanyl phthalocyanine crystal in the coating solution for the photosensitive layer during the production of the photosensitive layer can be made more excellent.

Further, in constituting the electrophotographic photosensitive member of the present invention, it is preferable to further contain an oxo titanyl phthalocyanine crystal other than the oxo titanyl phthalocyanine crystal having the characteristics (b) as a charge generator.
Thus, by using an oxotitanyl phthalocyanine crystal having a plurality of characteristics as a charge generating agent, it becomes easy to satisfy the relational expression (1), and an inexpensive electrophotographic photoreceptor can be provided.

Further, in constituting the electrophotographic photoreceptor of the present invention, it is preferable to contain an oxo titanyl phthalocyanine crystal having the following characteristics (c) as the oxo titanyl phthalocyanine crystal.
(C) After immersing in an organic solvent for 24 hours, the CuKα characteristic X-ray diffraction spectrum has a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° and a peak at 26.2 °. Not to be configured in this manner can further improve the temporal stability and dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer coating solution.

In constituting the electrophotographic photosensitive member of the present invention, it is preferable to set the oxo titanyl phthalocyanine concentration (C / wt%) in the single-layer type photosensitive layer to a value within the range of 0.6 to 3.0 wt%. .
With this configuration, since it becomes easy to satisfy the relational expression (1), a photosensitive layer having good dispersibility and sensitivity of the oxotitanyl phthalocyanine crystal and a uniform thickness can be easily obtained. Can be manufactured.

According to another aspect of the present invention, in an image forming apparatus provided with an electrophotographic photosensitive member, the electrophotographic photosensitive member includes at least a charge generating agent, a hole transporting agent, and an electron transporting agent on a substrate. An oxotitanyl phthalocyanine crystal having a Y-type crystal structure and having the following characteristics (b), and the concentration of the oxotitanyl phthalocyanine crystal in the single-layer type photosensitive layer: (C / wt%) is a value within the range of 0.6 to 3.0 wt%, and as a hole transporting agent, a concentration of 30 wt% and an electric field strength of 3.0 × 10 ⁵ V / cm In the photosensitive layer using a hole transporting agent whose mobility is a value in the range of 5.0 × 10 ⁻⁶ to 5.0 × 10 ⁻⁴ cm ² / V / sec. Reflection absorbance (A /-) for light and film thickness in photosensitive layer ( / M) and, the concentration of oxo-titanyl phthalocyanine crystal (C / wt%) in the photosensitive layer, but is an image forming apparatus which satisfies the following relation (1).
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it does not have a peak in the range of 50 to 200 ° C, but has one peak in the range of 296 to 400 ° C. When the layer satisfies the characteristic represented by the relational expression (1), the dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer can be improved, so that the exposure memory is effectively suppressed. Can do.
Moreover, exposure memory can be more effectively suppressed by setting the mobility of the hole transport agent to be used to a value within a predetermined range.
Furthermore, as the exposure memory described above can be suppressed, the movement of charges in the photosensitive layer can be performed efficiently, so that the sensitivity during exposure can also be improved.
Therefore, it is possible to provide an image forming apparatus such as a printer and a copier that can print a high-quality image with a suppressed exposure memory at a high speed.

In configuring the image forming apparatus of the present invention, it is preferable not to have a charge eliminating unit.
In this way, by adopting a so-called static elimination-less configuration that does not have the static elimination means, the image forming apparatus can be reduced in size and simplified, and the exposure memory can also be sufficiently suppressed.

In the first embodiment of the present invention, an electrophotographic photosensitive member having a single-layer type photosensitive layer containing at least a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin on a substrate. As the charge generating agent, an oxotitanyl phthalocyanine crystal having a Y-type crystal structure and having the following characteristics (b) is used, and the concentration (C / wt%) of the oxo titanyl phthalocyanine crystal in the single-layer type photosensitive layer is 0. The mobility measured under the conditions of a concentration in the range of .6 to 3.0 wt% and a concentration of 30 wt% and an electric field strength of 3.0 × 10 ⁵ V / cm as a hole transporting agent is 5 Reflective absorbance (A / −) for light having a wavelength of 700 nm in the photosensitive layer using a hole transporting agent having a value in the range of 0.0 × 10 ^{−6 to} 5.0 × 10 ⁻⁴ cm ² / V / sec. ), Film thickness (d / m) in the photosensitive layer, and photosensitive layer The concentration of definitive titanyl phthalocyanine crystal (C / wt%), but which is an electrophotographic photosensitive member and satisfies the following relation (1).
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it has no peak in the range of 50 to 200 ° C. and one peak in the range of 296 to 400 ° C. The electrophotographic photosensitive member of one embodiment will be described separately for each component.

1. Basic Configuration As shown in FIG. 1A, a single-layer type photoreceptor 10 has a single photoreceptor layer 14 provided on a substrate (conductive substrate) 12. The photosensitive layer 14 is characterized in that it contains oxotitanyl phthalocyanine crystal as a charge generating agent, a hole transport agent, an electron transport agent, and a binder resin in the same layer.
The reason is that the charge generated from the oxo titanyl phthalocyanine crystal as a charge generating agent at the time of exposure can be efficiently transported by including both a hole transporting agent and an electron transporting agent in the same photosensitive layer. Because it can.
Further, as shown in FIG. 1B, a photoreceptor 10 ′ in which a barrier layer 16 is formed between the substrate 12 and the photosensitive layer 14 within a range that does not impair the characteristics of the photoreceptor. Further, as shown in FIG. 1C, a photosensitive member 10 ″ having a protective layer 18 formed on the surface of the photosensitive layer 14 may be used.

2. Charge Generating Agent (1) Type As the charge generating agent used in the electrophotographic photosensitive member according to the present invention, an oxo titanyl phthalocyanine compound represented by the following general formula (1) is used.
The reason for this is that metal-free phthalocyanine generally used as a charge generator cannot sufficiently achieve high sensitivity in an electrophotographic photoreceptor, whereas oxotitanyl phthalocyanine represented by the general formula (1). This is because the quantum yield can be remarkably improved depending on the crystal form of a compound.
In addition, the compound represented by following formula (2) can be mentioned as a specific example of the oxo titanyl phthalocyanine compound represented by General formula (1).

(In the general formula (1), X ¹ , X ² , X ³ and X ⁴ are the same or different substituents, and each represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a cyano group, or a nitro group. And the repeating numbers a, b, c and d each represent an integer of 1 to 4, and may be the same or different.

The crystal form of the oxotitanyl phthalocyanine compound is Y-type.
This is because such a Y-type oxo titanyl phthalocyanine crystal improves the quantum yield in the charge generating agent, and can improve the sensitivity during exposure. That is, if the quantum yield is said to be about 90%, it is possible to efficiently generate charges according to the light irradiated by exposure, thereby sufficiently improving the sensitivity during exposure. This is because it can.

(2) Optical characteristics and thermal characteristics Further, the charge generating agent is characterized by containing an oxotitanyl phthalocyanine crystal having the following characteristics (b) .
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it does not have a peak in the range of 50 to 200 ° C, but has one peak in the range of 296 to 400 ° C. This is because such a configuration makes it possible to further improve the temporal stability and dispersibility of the oxotitanyl phthalocyanine crystal in the coating solution for the photosensitive layer.

Further, when the oxo titanyl phthalocyanine crystal has the characteristic (b), the aging stability and dispersibility of the oxo titanyl phthalocyanine crystal in the photosensitive layer coating solution can be further improved.
More specifically, in the case of having the characteristics (b), the oxotitanyl phthalocyanine crystal can suppress crystal transition in an organic solvent and exhibits particularly excellent dispersibility in a coating solution for a photosensitive layer. can do.
That is, when producing a photosensitive layer coating solution for producing a photosensitive layer, the crystal type does not transition to α or β type, and the Y type can be maintained, and the dispersibility in the photosensitive layer coating solution is particularly high. Since it is excellent, charge generation at the time of exposure in the formed photosensitive layer can be performed very efficiently. Furthermore, this excellent dispersibility enables efficient charge transport between the oxotitanyl phthalocyanine crystal and the charge transport agent, thereby preventing the generation of residual potential in the photosensitive layer and reducing the exposure memory. It can be effectively suppressed.

Moreover, it is preferable to further contain another oxo titanyl phthalocyanine crystal other than the oxo titanyl phthalocyanine crystal having the characteristics (b) as the charge generating agent.
The reason for this is that the oxo titanyl phthalocyanine crystal having no characteristics (b) by itself may have poor stability over time and dispersibility in the coating solution for the photosensitive layer, but the oxo titanyl phthalocyanine crystal having the characteristics (b). This is because the problem is remarkably improved by combining with titanyl phthalocyanine crystal .
That is, as long as a predetermined amount of the oxo titanyl phthalocyanine crystal having the characteristic (b) is used, even the conventional oxo titanyl phthalocyanine crystal having the characteristic (b) can be suitably used in combination. Therefore, by using an oxotitanyl phthalocyanine crystal having a plurality of characteristics as a charge generating agent in this way, it becomes easy to satisfy the relational expression (1) and an inexpensive electrophotographic photosensitive member can be provided.

Moreover, it is preferable to contain the oxo titanyl phthalocyanine crystal | crystallization which has the characteristic of the following (c) as a charge generator.
(C) After immersing in an organic solvent for 24 hours, the CuKα characteristic X-ray diffraction spectrum has a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° and a peak at 26.2 °. This is because, when the oxotitanyl phthalocyanine crystal has the characteristic (c), the oxo titanyl phthalocyanine crystal can control the crystal transition in the organic solvent more reliably.
That is, even when the oxo titanyl phthalocyanine crystal was actually immersed in an organic solvent such as tetrahydrofuran for 24 hours, it was confirmed that the crystal form did not transition to the α or β form and retained the Y form. This is because the crystal transition in the organic solvent can be reliably controlled.

Moreover, the optical characteristics in the above-mentioned oxotitanyl phthalocyanine crystal can be measured, for example, as follows.
First, 0.3 g of oxotitanyl phthalocyanine crystal was dispersed in 5 g of tetrahydrofuran and stored in a closed system for 24 hours under conditions of a temperature of 23 ± 1 ° C. and a relative humidity of 50-60% RH. A sample holder of RINT1100 manufactured by Denki Co., Ltd. can be filled and measured under the following conditions.
X-ray tube: Cu
Tube voltage: 40 kV
Tube current: 30 mA
Start angle: 3.0 °
Stop angle: 40.0 °
Scanning speed: 10 ° / min In addition, the measuring method of the thermal characteristic in an oxo titanyl phthalocyanine crystal | crystallization is described in the following Example.

(3) Ionization potential Moreover, it is preferable to make the value of the ionization potential in the oxo titanyl phthalocyanine as a charge generator into the value within the range of 5.0-5.5 eV.
The reason for this is that when the value of the ionization potential is less than 5.0 eV, the difference from the value of the ionization potential in the hole transport agent described later becomes excessively large, so that efficient charge transport becomes difficult. Because there is. As a result, the sensitivity of the photosensitive member is lowered and the exposure memory is caused. On the other hand, when the value of the ionization potential exceeds 5.5 eV, the difference from the value of the ionization potential in the hole transport agent described later becomes excessively small, and the charging characteristics in the photoconductor may deteriorate. Because.
Therefore, the ionization potential value of the oxotitanyl phthalocyanine is more preferably set to a value within the range of 5.1 to 5.4 eV, and further preferably set to a value within the range of 5.2 to 5.3 eV.
In addition, the measuring method of ionization potential can be measured, for example using an atmospheric-type ultraviolet photoelectron analyzer (Riken Keiki Co., Ltd. product, AC-1).

(4) Addition amount The addition amount of the oxotitanyl phthalocyanine crystal as the charge generating agent is characterized by being a value within the range of 0.6 to 3.0% by weight relative to the total amount .
The reason for this is that, by setting the amount of oxo titanyl phthalocyanine crystal to a value within such a range, when the photoconductor is exposed, the oxo titanyl phthalocyanine crystal can efficiently generate charges, This is because charge transport to and from the charge transport agent is also efficiently performed.
That is, when the amount of the oxotitanyl phthalocyanine crystal added is less than 0.6% by weight, the charge generation amount becomes insufficient and it becomes difficult to form a predetermined electrostatic latent image on the photoreceptor. Because there is. On the other hand, when the added amount of the charge generating agent exceeds 3% by weight, it may be difficult to uniformly disperse in the photosensitive layer coating solution.
Therefore, it is more preferable that the addition amount of the charge generating agent is a value within the range of 0.8 to 2.8% by weight with respect to the total amount.

3. Hole transport agent (1) Mobility The hole transport agent used in the electrophotographic photosensitive member according to the present invention is measured under the conditions of a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm. A hole transporting agent having a mobility within a range of 5.0 × 10 ⁻⁶ to 5.0 × 10 ⁻⁴ cm ² / V / sec is used.
The reason for this is that by setting the mobility of the hole transporting agent to a value within such a range, holes generated from the charge generating agent can be efficiently transported and the exposure memory can be more effectively suppressed. This is because it can.
That is, the mobility of the hole transport agent measured under the conditions of a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm is a value less than 5.0 × 10 ⁻⁶ cm ² / V / sec. This is because the holes generated by exposure cannot be sufficiently transported, and charges remain in the photosensitive layer, causing exposure memory and reducing sensitivity. On the other hand, the mobility of the hole transport agent measured under conditions of a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm exceeds 5.0 × 10 ⁻⁴ cm ² / V / sec. Then, since the hole transport ability is improved, it is preferable for suppressing exposure memory and improving sensitivity, but obtaining such a high-performance hole transport agent may be technically and costly difficult. Because. Further, the balance with the electron transporting ability of the electron transporting agent is lost, so that charges may remain in the photosensitive layer.

Here, the relationship between the mobility of the hole transport agent and the exposure memory potential in the photoreceptor will be described with reference to FIG.
In FIG. 2, the mobility (cm ² / V / sec) of the hole transport agent measured on the horizontal axis at a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm (logarithmic display) The vertical axis shows a characteristic diagram in which the exposure memory potential (V) is taken. As understood from the characteristic diagram, as the mobility (cm ² / V / sec) value of the hole transport agent increases, the value of the exposure memory potential (V) decreases. More specifically, when the mobility (cm ² / V / sec) of the hole transport agent is a value in the vicinity of 1.0 × 10 ⁻⁶ cm ² / V / sec, the exposure memory potential (V) is The value is around 100V. As the mobility (cm ² / V / sec) of the hole transport agent is increased to about 5.0 × 10 ⁻⁶ cm ² / V / sec, the value of the exposure memory potential (V) is about 60 ( V) is rapidly decreasing. As the mobility of the hole transport agent (cm ² / V / sec) is further increased, the value of the exposure memory potential (V) gradually decreases and maintains a value of less than 60V. ing.
Therefore, the mobility of the hole transport agent measured under the conditions of a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm is 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻⁴ cm. The value is more preferably in the range of ² / V / sec, and more preferably in the range of 2.0 × 10 ^{−5 to} 5.0 × 10 ⁻⁵ cm ² / V / sec.

(2) Kinds Specific examples of the hole transport agent that satisfies the above-described conditions include hole transport agents (HTM-A to F) represented by the following formulas (3) to (8).

(3) Ionization potential Moreover, as a hole transport agent, it is preferable to make the value of the ionization potential (eV) in the said hole transport agent into the value within the range of 5.1-6.0 eV.
The reason for this is that the ionization potential (eV) in the hole transport agent is set to a value in the range of 5.1 to 6.0 eV, as described in detail in the next section. This is because it becomes easy to adjust the value obtained by subtracting the value of the ionization potential (eV) in the oxotitanyl phthalocyanine compound from the value of (eV) within a predetermined range. Therefore, the value of ionization potential (eV) in the hole transport agent is more preferably in the range of 5.2 to 5.8 eV, and is preferably in the range of 5.3 to 5.7 eV. Is more preferable.

Further, as the hole transport agent, a value obtained by subtracting the ionization potential (eV) value of the oxotitanyl phthalocyanine compound from the ionization potential (eV) value of the hole transport agent is 0.1 to 0.4 (eV). It is preferable to use a hole transport agent having a value within the range.
The reason for this is that by using a hole transporting agent whose ionization potential (eV) value in the hole transporting agent is 0.1 to 0.4 eV greater than the ionization potential (eV) value in the oxotitanyl phthalocyanine compound, photosensitivity is achieved. This is because not only the exposure memory in the layer can be suppressed and the sensitivity can be improved, but also the charging characteristics can be improved.
That is, when the difference between the ionization potential (eV) of the hole transport agent and the ionization potential (eV) of the oxotitanyl phthalocyanine compound is less than 0.1 eV, the ionization potential in the hole transport agent and the oxo titanyl phthalocyanine compound This is because the charging characteristic of the photoconductor may be deteriorated because the difference from the ionization potential at is excessively small.
On the other hand, when the difference between the ionization potential (eV) of the hole transport agent and the ionization potential (eV) of the oxotitanyl phthalocyanine compound exceeds 0.4 eV, efficient charge transport becomes difficult. This is because the sensitivity may be reduced or an exposure memory may be generated.
Therefore, the difference between the ionization potential (eV) of the hole transport agent and the ionization potential (eV) of the oxotitanyl phthalocyanine compound is more preferably set to a value in the range of 0.12 to 0.35 eV. More preferably, the value is within the range of 15 to 0.3 eV.
In addition, the measuring method of the ionization potential in a hole transport agent can be measured, for example using an atmospheric-type ultraviolet photoelectron analyzer (the Riken Keiki Co., Ltd. product, AC-1).

(4) Addition amount The addition amount of the hole transfer agent is preferably set to a value in the range of 20 to 500 parts by weight with respect to 100 parts by weight of the binder resin.
This is because when the amount of the hole transporting agent added is less than 20 parts by weight, the hole transporting function in the photosensitive layer is lowered, which may adversely affect image characteristics. On the other hand, when the added amount of the hole transport agent exceeds 500 parts by weight, the dispersibility is lowered and crystallization is likely to occur.
Therefore, the amount of the hole transport agent added is more preferably set to a value within a range of 30 to 200 parts by weight, and a value within a range of 40 to 100 parts by weight with respect to 100 parts by weight of the binder resin. Is more preferable.

4). Electron Transfer Agent (1) Type As the electron transfer agent, any of various conventionally known electron transfer compounds can be used. In particular, benzoquinone compounds, diphenoquinone compounds, naphthoquinone compounds, malononitrile, thiopyran compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, fluorenone compounds [for example, 2,4,7-trinitro-9-fluorenone, etc. ], Dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride, 2,4,7-trinitrofluorenone imine compound, ethylated nitrofluorenone imine compound, tryptoan Thrin compound, tryptoanthrin imine compound, azafluorenone compound, dinitropyridoquinazoline compound, thioxanthene compound, 2-phenyl-1,4-benzoquinone compound, 2- Electrons such as salts of anion radicals and cations of phenyl-1,4-naphthoquinone compounds, 5,12-naphthacenequinone compounds, α-cyanostilbene compounds, 4, '-nitrostilbene compounds, and benzoquinone compounds Inhalable compounds are preferably used. These may be used alone or in combination of two or more.

  Specific examples of the electron transport agent described above include electron transport agents (ETM-A to D) represented by the following formulas (9) to (12).

(2) Addition amount The addition amount of the electron transfer agent is preferably set to a value within the range of 20 to 500 parts by weight with respect to 100 parts by weight of the binder resin.
This is because, when the amount of the electron transfer agent added is less than 20 parts by weight, the sensitivity is lowered and a practical problem may occur. On the other hand, when the added amount of the electron transport agent exceeds 500 parts by weight, the electron transport agent is easily crystallized, and it may be difficult to form an appropriate film as the photosensitive layer. Therefore, it is more preferable that the addition amount of the electron transport agent is a value within a range of 30 to 200 parts by weight, and a value within a range of 40 to 100 parts by weight with respect to 100 parts by weight of the binder resin. Is more preferable.

5. Binder resin As the binder resin, for example, styrene polymer, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic polymer, styrene-acrylic copolymer, Polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, ketone Thermoplastic resins such as resins, polyvinyl butyral resins, and polyether resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, and other crosslinkable thermosetting resins, and epoxy-acrylates, and Examples thereof include a photocurable resin such as urethane-acrylate. These binder resins can be used alone or in combination of two or more.
In constituting the electrophotographic photosensitive member of the present invention, a preferred binder resin includes a Z-type polycarbonate resin containing a structural unit represented by the following formula (13).

6). Additives In addition to the above-described components, various additives such as sensitizers, fluorene compounds, ultraviolet absorbers, plasticizers, surfactants, and leveling agents may be added to the photosensitive layer. it can. In order to improve the sensitivity of the photoreceptor, sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.

7). Substrate As the substrate on which the above-described photosensitive layer is formed, various conductive materials can be used. For example, a conductive substrate formed of a metal such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, or the above-mentioned Examples include a substrate made of a plastic material on which a metal is deposited or laminated, or a glass substrate coated with aluminum iodide, tin oxide, indium oxide, or the like.
That is, it is only necessary that the substrate itself has conductivity or the surface of the substrate has conductivity. Further, it is preferable that the substrate has sufficient mechanical strength when used.
The shape of the substrate may be any of a sheet shape and a drum shape according to the structure of the image forming apparatus to be used.

8). Photosensitive layer (1) Relational expression (1)
Further, the reflection absorbance (A / −) with respect to light having a wavelength of 700 nm in the photosensitive layer, the film thickness (d / m) in the photosensitive layer, the concentration of oxotitanyl phthalocyanine crystal in the photosensitive layer (C / wt%), Satisfies the following relational expression (1).
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
This is because, if the photosensitive layer satisfies the relational expression (1), the dispersibility of the oxotitanyl phthalocyanine crystal as the charge generating agent in the photosensitive layer can be made sufficient. Therefore, if the photosensitive layer satisfies the relational expression (1), the exposure memory can be effectively suppressed. In addition, if the exposure memory can be suppressed in this way, the movement of charges in the photosensitive layer can be performed efficiently, so that the sensitivity during exposure can also be improved.

The left side (A · C ⁻¹ · d ⁻¹ ) in the relational expression (1) is regarded as a parameter representing the dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer according to the Lambert-Beer law. Can do.
That is, when the film thickness (d / m) and the concentration of the oxotitanyl phthalocyanine crystal (C / wt%) in the photosensitive layer are constant, the incident light is difficult to be absorbed if the dispersibility of the oxo titanyl phthalocyanine crystal is insufficient. This is because the reflected absorbance (A) with respect to light having a wavelength of 700 nm tends to be a small value. On the other hand, if the dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer is good, incident light is easily absorbed, and the reflection absorbance (A) with respect to light having a wavelength of 700 nm in the photosensitive layer becomes a large value.
Therefore, it can be seen from this reason that the dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer can be evaluated from the value of the left side (A · C ⁻¹ · d ⁻¹ ) in the relational expression (1).

Referring to FIG. 3, the numerical value of the left side A · C ⁻¹ · d ⁻¹ in the relational expression (1) (unit: 1 / (weight% · m), the same applies hereinafter) and the photoconductor. The relationship with the exposure memory potential will be described.
In FIG. 3, the horizontal axis represents the value of the left side A · C ⁻¹ · d ⁻¹ in the relational expression (1), and the vertical axis represents the characteristic curve taking the exposure memory potential (V) of the photoreceptor. .
As can be understood from the characteristic curve, the value of the exposure memory potential (V) increases as the value of the left side A · C ⁻¹ · d ⁻¹ in the relational expression (1) approaches 1 × 10 ^4. As the value of the left side A · C ⁻¹ · d ⁻¹ in 1) becomes larger, the value of the exposure memory potential (V) becomes smaller. More specifically, when the value of the left side A · C ⁻¹ · d ⁻¹ in the relational expression (1) is in the range of 1 × 10 ^{4 to} 1.75 × 10 ⁴ , the value rapidly increases as the value increases. It can be seen that the value of the exposure memory potential (V) is lowered. On the other hand, in the range where the value of the left side A · C ⁻¹ · d ⁻¹ in the relational expression (1) is 1.75 × 10 ⁴ or more, the value of the exposure memory potential (V) increases as the value increases. It can be seen that the value decreases gradually and takes a value within the range of 70V or less.
Therefore, the value of A · C ⁻¹ · d ^{−1 on} the left side in the relational expression (1) is more preferably 1.9 × 10 ⁴ or more, and 2.0 × 10 ⁴ or more. Is more preferable.

(2) Reflectance Absorbance Further, the value of the reflection absorbance (A / −) with respect to light having a wavelength of 700 nm in the photosensitive layer is preferably set to a value within the range of 0.7 to 0.9.
This is because the thickness of the photosensitive layer (d / m) and the thickness of the oxo layer in the photosensitive layer are adjusted by setting the reflection absorbance of the photosensitive layer to light having a wavelength of 700 nm within the range of 0.7 to 0.9. This is because it is easy to adjust the value of the titanyl phthalocyanine crystal concentration (C / wt%) to form a photosensitive layer having characteristics satisfying the relational expression (1). Furthermore, if the reflection absorbance is in such a range, the sensitivity can be improved more effectively while suppressing the exposure memory even under the conditions defined by the relational expression (1).
That is, when the value of the reflection absorbance with respect to light having a wavelength of 700 nm in the photosensitive layer is less than 0.7, the amount of oxotitanyl phthalocyanine crystals added in the photosensitive layer is too small and the charge generation amount becomes insufficient. This is because it may be difficult to form a predetermined electrostatic latent image. Alternatively, the film thickness in the photosensitive layer becomes excessively small, and the mechanical strength as the photosensitive member may be insufficient. On the other hand, when the value of the reflection absorbance with respect to light having a wavelength of 700 nm in the photosensitive layer exceeds 0.9, the film thickness in the photosensitive layer or the concentration value of the oxotitanyl phthalocyanine crystal in the photosensitive layer becomes excessively large. This is because it may not be possible to evaluate the dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer using the formula (1).
Therefore, it is more preferable to set the value of the reflection absorbance with respect to light having a wavelength of 700 nm in the photosensitive layer to a value in the range of 0.72 to 0.88, and to a value in the range of 0.75 to 0.85. Is more preferable.
In addition, the measuring method of reflected absorbance will be described in detail in a later example.

(3) Film thickness The film thickness (d / m) in the photosensitive layer is preferably set to a value in the range of 5.0 × 10 ^{−6 to} 1.0 × 10 ⁻⁴ m.
The reason for this is that the film thickness (d / m) in the photosensitive layer is set to a value within the range of 5.0 × 10 ^{−6 to} 1.0 × 10 ⁻⁴ m, so that the photosensitive layer has a wavelength of 700 nm. Adjusting the value of the reflection absorbance (A / −) and the value of the concentration (C / wt%) of the oxo titanyl phthalocyanine crystal in the photosensitive layer to form a photosensitive layer having characteristics satisfying the relational expression (1). This is because it becomes easy. Furthermore, if the film thickness (d / m) of the photosensitive layer is in such a range, it is possible to obtain a photoconductor excellent in practicality even under the conditions defined by the relational expression (1).
That is, when the film thickness (d / m) in the photosensitive layer is less than 5.0 × 10 ⁻⁶ m, the mechanical strength as the photosensitive member may be insufficient. On the other hand, when the film thickness (d / m) of the photosensitive layer exceeds 1.0 × 10 ⁻⁴ m, it may be easily peeled off from the substrate. Therefore, the film thickness (d / m) in the photosensitive layer is more preferably set to a value in the range of 1.0 × 10 ^{−5 to} 8.0 × 10 ⁻⁵ m, and more preferably from 2.0 × 10 ⁻⁵ to More preferably, the value is within the range of 4.0 × 10 ⁻⁵ m.

9. Manufacturing method In addition, in manufacturing a single-layer type photoreceptor, a binder resin, a charge generating agent, a hole transporting agent, and an electron transporting agent are added to a solvent, dispersed and mixed, and coated for a photosensitive layer. Use liquid. That is, when a single layer type photoreceptor is formed by a coating method, a known method including an oxo titanyl phthalocyanine crystal as a charge generating agent, a hole transport agent, an electron transport agent, a binder resin, and the like together with an appropriate solvent. For example, a dispersion liquid may be prepared by dispersing and mixing using a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic disperser or the like, and this may be applied and dried by a known means.
Moreover, as a solvent for making the coating liquid for photosensitive layers, 1 type (s) or 2 or more types, such as tetrahydrofuran, a dichloromethane, toluene, 1, 4- dioxane, and 1-methoxy-2-propanol, are mentioned.
Furthermore, in order to improve the dispersibility of the charge transport agent and the charge generator and the smoothness of the surface of the photoreceptor layer, a surfactant, a leveling agent, and the like may be added to the photosensitive layer coating solution. .

[Second Embodiment]
According to a second embodiment of the present invention, in an image forming apparatus including an electrophotographic photosensitive member, the electrophotographic photosensitive member includes at least a charge generating agent, a hole transporting agent, and an electron transporting agent on a substrate. And a single-layer photosensitive layer having a Y-type crystal structure and having the following characteristics (b) as a charge generator: The concentration (C / wt%) of the oxotitanyl phthalocyanine crystal at a value in the range of 0.6 to 3.0 wt%, a concentration of 30 wt% as the hole transport agent , and an electric field strength of 3.0 x 10 ^A hole transporting agent having a mobility measured under a condition of ⁵ V / cm within a range of 5.0 × 10 ⁻⁶ to 5.0 × 10 ⁻⁴ cm ² / V / sec, and , Reflectance Absorbance (A /-) for light having a wavelength of 700 nm in the photosensitive layer The image forming apparatus is characterized in that the film thickness (d / m) in the photosensitive layer and the concentration (C / wt%) of the oxotitanyl phthalocyanine crystal in the photosensitive layer satisfy the following relational expression (1): .
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it has no peak in the range of 50 to 200 ° C. and one peak in the range of 296 to 400 ° C. The content already described in the first embodiment will be omitted, and the second embodiment will be described focusing on differences from the first embodiment.

That is, as the configuration of the image forming apparatus of the second embodiment, a configuration like the image forming apparatus 100 shown in FIG. 4 is preferably used.
Here, FIG. 4 is a schematic diagram showing the overall configuration of the image forming apparatus. Hereinafter, the operation will be described in order.
First, the photosensitive member 111 of the image forming apparatus 100 is rotated at a predetermined process speed (peripheral speed) in the direction indicated by the arrow A, and then the surface is charged to a predetermined potential by the charging unit 112.
Next, the exposure unit 113 exposes the surface of the photoconductor 111 through a reflection mirror or the like while being optically modulated according to image information. By this exposure, an electrostatic latent image is formed on the surface of the photoreceptor 111.
Next, based on the electrostatic latent image, latent image development is performed by the developing unit 114. The developing means 114 contains toner, and the toner adheres corresponding to the electrostatic latent image on the surface of the photoconductor 111 to form a toner image.
Further, the recording paper 120 is conveyed to the lower part of the photoconductor along a predetermined transfer conveyance path. At this time, a toner image can be transferred onto the recording material 120 by applying a predetermined transfer bias between the photosensitive member 111 and the transfer unit 115.

Next, the recording paper 120 on which the toner image has been transferred is separated from the surface of the photoreceptor 111 by a separating unit (not shown) and conveyed to a fixing device by a conveying belt. Next, the toner image is fixed on the surface by being heated and pressed by the fixing device, and then discharged to the outside of the image forming apparatus 100 by a discharge roller.
On the other hand, the photoconductor 111 after the transfer of the toner image continues to rotate, and residual toner (adhered matter) that has not been transferred to the recording paper 120 at the time of transfer is removed from the surface of the photoconductor 111 by the cleaning device 117.

In the present invention, the above-described photoreceptor 111 has a single-layer photosensitive layer containing at least a charge generator, a hole transport agent, an electron transport agent, and a binder resin on a substrate, As the generator , an oxotitanyl phthalocyanine crystal having a Y-type crystal structure and having the following characteristics (b) is used, and the concentration (C / wt%) of the oxo titanyl phthalocyanine crystal in the single-layer type photosensitive layer is 0.6 to The mobility measured under the conditions of a value within the range of 3.0% by weight and the concentration of 30% by weight and the electric field strength of 3.0 × 10 ⁵ V / cm as the hole transporting agent is 5.0 ×. Reflective absorbance (A / −) with respect to light having a wavelength of 700 nm in the photosensitive layer, using a hole transporting agent having a value in the range of 10 ^{−6 to} 5.0 × 10 ⁻⁴ cm ² / V / sec, The film thickness (d / m) in the photosensitive layer and the thickness in the photosensitive layer The concentration of Soviet titanyl phthalocyanine crystal (C / wt%), but which satisfies the following relation (1).
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
(B) In the differential scanning calorimetry, it has no peak in the range of 50 to 200 ° C. except for the peak due to vaporization of the adsorbed water, and therefore has one peak in the range of 296 to 400 ° C. As described in detail in the first embodiment, the photoconductor 111 effectively suppresses the exposure memory and is excellent in sensitivity at the time of exposure.
Therefore, the image forming apparatus 100 according to the present invention can print a high-quality image in which the exposure memory is suppressed at a high speed.

In the image forming apparatus of the present invention, it is preferable not to have a charge eliminating unit.
This is because, as described above, the image forming apparatus 100 according to the present invention can sufficiently suppress the exposure memory. Therefore, even if the step of erasing the exposure memory or the like by the charge eliminating unit is omitted, This is because a high-quality image can be formed.
Therefore, the configuration of the image forming apparatus can be simplified, and the image forming apparatus can be downsized.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these description content.

[Reference Example 1]
1. Production of electrophotographic photoreceptor Using a ball mill, Y-type oxotitanyl phthalocyanine (TiOPc) represented by the formula (2) having the characteristics represented by (TiOPc-A) in Table 1 The mobility measured under the conditions of 3 parts by weight of phthalocyanine, a concentration of 30% by weight represented by the formula (3), and an electric field strength of 3.0 × 10 ⁵ V / cm is 1.0 × 10 ⁻⁵ cm ² / 45 parts by weight of a hole transporting agent (HTM-A) that is V / sec, 30 parts by weight of an electron transporting agent (ETM-C) represented by the formula (11), and a viscosity average molecular weight of 20, 100 parts by weight of Z-type polycarbonate (Resin-A) (TS2020, manufactured by Teijin Chemicals Ltd.) represented by the formula (13), which is 000, is mixed and dispersed with 800 parts by weight of tetrahydrofuran for 50 hours to form a photosensitive layer. for The coating liquid was manufactured.
Next, this photosensitive layer coating solution was applied to an aluminum drum-shaped support having a diameter of 30 mm and a total length of 254 mm as a substrate by a dip coating method. Thereafter, it was dried with hot air at 100 ° C. for 40 minutes to produce an electrophotographic photoreceptor having a single-layer type photosensitive layer having a thickness of 2.5 × 10 ⁻⁵ m.

TiOPc-A was prepared by the method described in Japanese Patent No. 3463032 .
TiOPc-B was prepared by the method described in Example 8.

2. DSC measurement in oxo titanyl phthalocyanine crystal The DSC (differential scanning calorimetry) of the oxo titanyl phthalocyanine crystal (TiOPc-A) used was a differential scanning calorimeter (TAS-200 type, DSC 8230D manufactured by Rigaku Corporation). Used. The measurement conditions are as follows. FIG. 5 shows the obtained differential scanning calorimetry chart.
Sample pan: Aluminum heating rate: 20 ° C / min

3. Evaluation of Electrophotographic Photoreceptor (1) Reflection Absorbance Measurement Reflection absorbance (A ₁ ) with respect to light having a wavelength of 700 nm in a support substrate on which the obtained photosensitive layer (reference thickness 2.5 × 10 ⁻⁵ m) was laminated. Was measured using a color difference meter (manufactured by Minolta Co., Ltd., color difference meter CM1000). Next, the reflection absorbance (A ₂ ) with respect to light having a wavelength of 700 nm in a supporting substrate on which no photosensitive layer was laminated was measured in the same manner.
6A and 6B, more specifically, FIG. 6A shows a state where the photosensitive layer 14 is laminated on the support base 12, and FIG. b) shows the state of the support base 12 alone. In FIGS. 6A and 6B, I ₀ represents the intensity of light (incident light) irradiated to each supporting substrate, and I ₁ and I ₂ represent the respective supporting substrates. It represents the intensity of the reflected light in the incident light irradiated. Therefore, in order to eliminate the influence of the support substrate and obtain the reflection absorbance in the photosensitive layer, subtract the A ₂ that is the reflection absorbance of the support substrate from A ₁ where the reflection absorbance of the photosensitive layer and the support substrate is mixed. Just pull it.
Therefore, the reflection absorbance (A) of the photosensitive layer is calculated from the following formula (1) based on the obtained reflection absorbance values (A ₁ , A ₂ ), and the reflection absorbance (A) is calculated as follows: In light of the criteria, the dispersibility of the oxotitanyl phthalocyanine crystals in the photosensitive layer was evaluated. The obtained results are shown in Table 1.
The reflected absorbance (A ₁ ) in FIG. 6 (a) is calculated from the following formula (2). Similarly, the reflected absorbance (A ₂ ) in FIG. 6 (b) is calculated from the following formula (3). The The larger the reflection absorbance (A) of the photosensitive layer is, the more light is absorbed by the photosensitive layer. That is, it shows that the dispersibility of the oxo titanyl phthalocyanine crystal in the photosensitive layer is high. The reflection absorbance A of the photosensitive layer in Example 1 was 0.810.
Here, the calculation of A · C ⁻¹ · d ^{−1 in} the first embodiment will be specifically described. First, the concentration C is a total of 3 parts by weight of (TiOPc-A), 45 parts by weight of a hole transporting agent (HTM-A), 30 parts by weight of an electron transporting agent (ETM-C), and 100 parts by weight of a binder resin. From the ratio of (TiOPc-A) to 178.0 (3 / 178.0) × 100 = 1.69, C = 1.69 (% by weight) was obtained. By substituting this value, the reflection absorbance and the film thickness in the photosensitive layer described above, A · C ⁻¹ · d ⁻¹ = 0.810 / {1.69 (wt%) × 2.5 × 10 ^{− 5} (m)} = 1.92 × 10 ⁴ was determined.

(2) Measurement of exposure memory potential The exposure memory potential of the obtained electrophotographic photosensitive member was measured under the following conditions.
That is, the obtained electrophotographic photosensitive member is mounted on a printer (Antico 40 manufactured by Kyocera Mita Co., Ltd.) in which a charge eliminating lamp is omitted, and the surface potential of an unexposed portion (corresponding to a blank portion in a formed image) and an exposed portion ( The surface potential after the charging step (corresponding to a solid black portion in the formed image) was measured, and the difference was evaluated as the exposure memory potential according to the following criteria. The obtained results are shown in Table 2.
A: Memory potential is less than 70 (V).
○: Memory potential is a value less than 70-80 (V).
Δ: Memory potential is a value less than 80 to 90 (V).
X: Memory potential is a value of 90 (V) or more.

(3) Evaluation of exposure memory image Moreover, the evaluation of the exposure memory image when image formation was performed using the obtained electrophotographic photosensitive member was performed under the following conditions.
That is, the obtained electrophotographic photosensitive member was mounted on a printer (Antico 40 manufactured by Kyocera Mita Co., Ltd.) modified to have a drum peripheral speed of 100 mm / sec with the charge eliminating lamp omitted, and a printing test was performed. In such a printing test, it was determined whether or not an exposure memory image was visually generated after printing 1,000 originals of 5% density text. More specifically, in the printing test, an original as shown in FIG. 7 was used, and it was determined whether or not a ghost image of a solid black portion occurred in the gray portion. Moreover, this judgment result was evaluated according to the following criteria. The obtained results are shown in Table 2.
A: Memory image is not observed.
○: A slight memory image is observed.
Δ: A memory image is observed.
X: A memory image is observed remarkably.

(4) Sensitivity measurement Moreover, the sensitivity measurement of the obtained photoreceptor was measured under the following conditions.
That is, using a drum sensitivity tester (Gentec Co., Ltd.), a monochromatic light having a wavelength of 780 nm extracted from the white light of a halogen lamp using a bandpass filter while the surface potential of the photoconductor is charged to + 850V. The surface of the photoconductor was irradiated with (full width at half maximum of 20 nm, light intensity of 1.5 μJ / m ² ) for 50 msec. Next, the surface potential at the time when 0.35 seconds passed from the start of exposure was measured as sensitivity. Further, the measurement results were evaluated according to the following criteria. The obtained results are shown in Table 2.
A: The sensitivity value is less than 105 (V).
A: The sensitivity value is 105 (V) or more and less than 125 (V).
X: The sensitivity value is 125 (V) or more.

(5) Comprehensive evaluation Moreover, comprehensive evaluation which integrated the evaluation in the exposure memory electric potential mentioned above, an exposure memory image, and a sensitivity was implemented according to the following reference | standard. The obtained results are shown in Table 2.
A: All items have not been evaluated as Δ or ×.
X: In all items, at least one evaluation of Δ or x is received.

[ Reference Examples 2 to 7 and Examples 8 to 9 ]
In Reference Examples 2 to 7 and Examples 8 to 9 , the Y-type oxotitanyl phthalocyanine crystal (TiOPc-A) used in Reference Example 1 and the positive formula represented by the formula (3) were used when producing the photoreceptor. Instead of the hole transporting agent (HTM-A), as shown in Table 2, Y-type oxotitanyl phthalocyanine crystals (TiOPc-A, B, and C) and positive ones represented by formulas (3) to (8) are used. A photoconductor was produced and evaluated in the same manner as in Example 1 except that the hole transport agents (HTM-A to F) were used. The obtained results are shown in Table 2.
The properties of each Y-type oxotitanyl phthalocyanine crystal are shown in Table 1.

Moreover, the manufacturing method of the Y type oxo titanyl phthalocyanine crystal | crystallization (TiOPc-B) used in Example 8 and 9 is shown below.
1. Production of titanyl phthalocyanine In an argon-substituted flask, 22 g (0.17 mol) of o-phthalonitrile, 25 g (0.073 mol) of titanium tetrabutoxide, 2.28 g (0.038 mol) of urea and 300 g of quinoline The mixture was heated to 150 ° C. while stirring. Next, after evaporating the steam generated from the reaction system, the temperature was raised to 215 ° C. while the reaction temperature was maintained, and the reaction was further continued for 2 hours while maintaining the reaction temperature.
After completion of the reaction, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out from the flask, filtered through a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol and then vacuum-dried. 24 g of a purple solid was obtained.

2. Production of titanyl phthalocyanine crystal (1) Pre-acid treatment step 10 g of the blue-purple solid obtained in the production of the titanyl phthalocyanine compound described above was added to 100 ml of N, N-dimethylformamide and heated to 130 ° C. with stirring. For 2 hours. Next, heating was stopped when 2 hours passed, and after cooling to 23 ± 1 ° C., stirring was stopped, and the liquid was allowed to stand in this state for 12 hours for stabilization treatment. Subsequently, the stabilized liquid was filtered off with a glass filter, and the obtained solid was washed with methanol and then vacuum-dried to obtain 9.83 g of a crude crystal of a titanyl phthalocyanine compound.

(2) Acid treatment step 5 g of the crude crystal of titanyl phthalocyanine obtained in the above-mentioned pre-acid treatment step was added to 100 ml of concentrated sulfuric acid and dissolved. Next, this solution was added dropwise to ice-cooled water, stirred for 15 minutes at room temperature, and then allowed to stand at about 23 ± 1 ° C. for 30 minutes for recrystallization. Next, the liquid described above was filtered off with a glass filter, and the obtained solid was washed with water until the washing liquid became neutral, and then dispersed in 200 ml of chlorobenzene in the presence of water without drying. The mixture was heated to 0 ° C. and stirred for 10 hours. Next, after filtering the liquid through a glass filter, the obtained solid was vacuum-dried at 50 ° C. for 5 hours to obtain 4.1 g of an unsubstituted titanyl phthalocyanine crystal (blue powder) represented by the formula (2). Obtained.
Further, the differential scanning calorimetry in the Y-type oxotitanyl phthalocyanine crystal (TiOPc-B) used in Examples 8 and 9 was measured using the same method as in Example 1. In addition, the differential scanning calorimetry chart obtained in FIG. 8 is shown.

[Comparative Examples 1-2]
In Comparative Examples 1 and 2, when manufacturing the photoreceptor, the Y-type oxotitanyl phthalocyanine crystal (TiOPc-A) used in Example 1 and the hole transporting agent (HTM-) represented by the formula (3) were used. Instead of A), Y-type oxotitanyl phthalocyanine crystals (TiOPc-D) and hole transporting agents (HTM-A to B) represented by formulas (3) to (4) are used as shown in Table 2, respectively. Except for the use, a photoreceptor was prepared and evaluated in the same manner as in Example 1. The obtained results are shown in Table 2.
The properties of the used Y-type oxotitanyl phthalocyanine crystal (TiOPc-D) are shown in Table 1.

[Comparative Example 3]
In Comparative Example 3, it is represented by the following formula (14) instead of the hole transporting agent (HTM-A) represented by the formula (3) used in Example 1 when producing the photoreceptor. A photoconductor was produced and evaluated in the same manner as in Example 1 except that the hole transport agent (HTM-G) was used. The obtained results are shown in Table 2.

[Comparative Example 4]
In Comparative Example 4, it is represented by the following formula (15) instead of the hole transport agent (HTM-A) represented by the formula (3) used in Example 1 when manufacturing the photoreceptor. A photoconductor was produced and evaluated in the same manner as in Example 1 except that the hole transport agent (HTM-H) was used. The obtained results are shown in Table 2.

[Comparative Example 5]
In Comparative Example 5, it is represented by the following formula (16) instead of the hole transport agent (HTM-A) represented by the formula (3) used in Example 1 when producing the photoreceptor. A photoconductor was produced and evaluated in the same manner as in Example 1 except that the hole transport agent (HTM-I) was used. The obtained results are shown in Table 2.

[Comparative Example 6]
In Comparative Example 6, it is represented by the following formula (17) instead of the hole transporting agent (HTM-A) represented by the formula (3) used in Example 1 when producing the photoreceptor. A photoconductor was produced and evaluated in the same manner as in Example 1 except that the hole transport agent (HTM-J) was used. The obtained results are shown in Table 2.

[Comparative Examples 7-8]
In Comparative Examples 7 to 8, when manufacturing the photoreceptor, the Y-type oxotitanyl phthalocyanine crystal (TiOPc-A) used in Example 1 and the hole transport agent (HTM-) represented by the formula (3) were used. Instead of A), Y-type oxotitanyl phthalocyanine crystals (TiOPc-E) and hole transporting agents (HTM-A to B) represented by formulas (3) to (4) are used as shown in Table 2, respectively. Except for the use, a photoreceptor was prepared and evaluated in the same manner as in Example 1. The obtained results are shown in Table 2.
The characteristics of the Y-type oxotitanyl phthalocyanine crystal used are shown in Table 1.

According to the electrophotographic photosensitive member and the image forming apparatus of the present invention, in the single-layer type photosensitive member, the reflection absorbance, the film thickness, and the like in the photosensitive layer are determined so as to satisfy the relational expression (1), and the charge used By limiting the type of the generating agent and the characteristics of the hole transport agent, not only the exposure memory can be suppressed, but also the sensitivity can be improved.
Therefore, the electrophotographic photosensitive member and the image forming apparatus of the present invention are expected to contribute to high image quality and high speed of the image forming apparatus.

(A)-(c) is a figure provided in order to demonstrate the structure of a single layer type photoreceptor. It is a figure provided in order to demonstrate the relationship between the mobility of a hole transport agent, and exposure memory potential. It is a figure provided in order to demonstrate the relationship between the left side in relational expression (1), and exposure memory electric potential. 1 is a diagram for explaining a schematic configuration of an image forming apparatus including an electrophotographic photosensitive member according to the present invention. It is a figure which shows the chart in the differential scanning calorimetry of TiPc-A which is a charge generation agent. It is a figure provided in order to demonstrate the measuring method of the reflected light absorbency in a photosensitive layer. It is a figure provided in order to demonstrate a memory image. It is a figure which shows the chart in the differential scanning calorimetry of TiPc-B which is a charge generation agent.

Explanation of symbols

10: single layer type photoreceptor 10 ': single layer type photoreceptor 10 ": single layer type photoreceptor 12: substrate 14: photosensitive layer 16: barrier layer 18: protective layer 100: image forming apparatus 111: electrophotographic photoreceptor 112: Charging means 113: Exposure means 114: Developing means 115: Transfer means 117: Cleaning device 120: Recording paper

Claims (7)

In an electrophotographic photoreceptor having a single-layer type photosensitive layer containing at least a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin on a substrate,
As the charge generating agent, an oxo titanyl phthalocyanine crystal having a Y-type crystal structure and having the following characteristics (b) is used, and the concentration (C / wt%) of the oxo titanyl phthalocyanine crystal in the single-layer type photosensitive layer is 0. A value within the range of 6 to 3.0% by weight,
And,
As the hole transport agent, a mobility measured under conditions of a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm is 5.0 × 10 ⁻⁶ to 5.0 × 10 ⁻⁴ cm ^2. Using a hole transporting agent having a value within the range of / V / sec,
Furthermore, the reflection absorbance (A / −) for light having a wavelength of 700 nm in the photosensitive layer, the film thickness (d / m) in the photosensitive layer, and the concentration (C / wt%) of oxotitanylphthalocyanine crystals in the photosensitive layer. Satisfies the following relational expression (1).
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it has no peak in the range of 50 to 200 ° C and one peak in the range of 296 to 400 ° C. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge generating agent is an oxo titanyl phthalocyanine crystal having the following property (c).
(C) After immersing in an organic solvent for 24 hours, the CuKα characteristic X-ray diffraction spectrum has a maximum peak at least at Bragg angle 2θ ± 0.2 ° = 27.2 ° and a peak at 26.2 °. Not to do   3. The electrophotographic photosensitive member according to claim 1, further comprising an oxo titanyl phthalocyanine crystal other than the oxo titanyl phthalocyanine crystal having the characteristic (b) as the charge generating agent. In an image forming apparatus provided with an electrophotographic photosensitive member,
The electrophotographic photosensitive member has a single-layer type photosensitive layer containing at least a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin on a substrate,
As the charge generating agent, an oxo titanyl phthalocyanine crystal having a Y-type crystal structure and having the following characteristics (b) is used, and the concentration (C / wt%) of the oxo titanyl phthalocyanine crystal in the single-layer type photosensitive layer is 0. A value within the range of 6 to 3.0% by weight,
And,
As the hole transport agent, a mobility measured under conditions of a concentration of 30% by weight and an electric field strength of 3.0 × 10 ⁵ V / cm is 5.0 × 10 ⁻⁶ to 5.0 × 10 ⁻⁴ cm ^2. Using a hole transporting agent having a value within the range of / V / sec,
Furthermore, the reflection absorbance (A / −) for light having a wavelength of 700 nm in the photosensitive layer, the film thickness (d / m) in the photosensitive layer, and the concentration (C / wt%) of oxotitanylphthalocyanine crystals in the photosensitive layer. Satisfies the following relational expression (1).
A · C ⁻¹ · d ⁻¹ > 1.75 × 10 ⁴ (1)
(B) In differential scanning calorimetry, except for the peak accompanying vaporization of adsorbed water, it has no peak in the range of 50 to 200 ° C and one peak in the range of 296 to 400 ° C. 5. The image forming apparatus according to claim 4, wherein the charge generating agent is an oxo titanyl phthalocyanine crystal having the following characteristic (c).
(C) After immersing in an organic solvent for 24 hours, the CuKα characteristic X-ray diffraction spectrum has a maximum peak at least at Bragg angle 2θ ± 0.2 ° = 27.2 ° and a peak at 26.2 °. Not to do   6. The image forming apparatus according to claim 4, further comprising an oxo titanyl phthalocyanine crystal other than the oxo titanyl phthalocyanine crystal having the characteristic (b) as the charge generating agent.   The image forming apparatus according to claim 4, wherein the image forming apparatus does not include a charge eliminating unit.