JP4336677B2 - 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 and an image forming apparatus that can effectively suppress generation of exposure memory.

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.

Accordingly, the inventors of the present invention have made extensive studies and, as a result, in the single-layer type photoreceptor, the reflection absorbance, film thickness, etc. in the photosensitive layer satisfy the predetermined relationship, and the charge generator and hole used are It has been found that by defining the characteristics of the 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 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, the charge generating agent is provided. As a hole transporting agent, the ionization potential (eV) of the hole transporting agent is used as the hole transporting agent, and the ionization in the oxotitanyl phthalocyanine is a Y-type crystal structure having the following characteristics (b): A reflection absorbance (A / A) for a light having a wavelength of 700 nm in a photosensitive layer using a hole transporting agent having a value obtained by subtracting the value of potential (eV) within a range of 0.1 to 0.4 (eV). -), The film thickness (d / m) in the photosensitive layer, and the concentration (C / wt%) of oxotitanyl phthalocyanine in the photosensitive layer satisfy the following relational expression (1). A characteristic electrophotographic photosensitive member is provided, and the above-described problems can be solved.
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 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C. except for the peak accompanying vaporization of adsorbed water.
That is, when the photosensitive layer satisfies the characteristics represented by the relational expression (1), the dispersibility of oxotitanyl phthalocyanine in the photosensitive layer can be improved, so that the exposure memory is effectively suppressed. can do.
Further, the exposure memory can be more effectively suppressed by setting the difference in ionization potential between the oxotitanyl phthalocyanine as the charge generating agent and the hole transporting agent 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.

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

In constituting the electrophotographic photosensitive member of the present invention, oxo titanyl phthalocyanine having the following characteristic (b) is contained as a charge generator .
(B) In the differential scanning calorimetry, it has no peak in the range of 50 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C., except for the peak accompanying vaporization of adsorbed water.
By comprising in this way, the temporal stability and dispersibility of the oxo titanyl phthalocyanine crystal | crystallization in the coating liquid for photosensitive layers at the time of manufacture of a photosensitive layer can be made more excellent.

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

In constituting the electrophotographic photosensitive member of the present invention, it is preferable to contain oxotitanyl phthalocyanine having the following characteristics (c) as oxo titanyl phthalocyanine.
(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 °. Don't do it.
By comprising in this way, the temporal stability and dispersibility of the oxo titanyl phthalocyanine crystal | crystallization in the coating liquid for photosensitive layers can be made further excellent.

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%. .
By comprising in this way, it becomes easy to satisfy the relational expression (1), and it is possible to easily produce a photosensitive layer having good dispersibility and sensitivity of oxotitanylphthalocyanine and having a uniform thickness. Can do.

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. And oxo titanyl phthalocyanine having a Y-type crystal structure and having the following characteristics (b) as the charge generating agent , and the positive transport agent as the positive hole transport agent. A hole transporting agent in which a value obtained by subtracting a value of ionization potential (eV) in oxotitanyl phthalocyanine from a value of ionization potential (eV) in the hole transporting agent is a value within a range of 0.1 to 0.4 (eV). And the reflection absorbance (A / −) of the photosensitive layer with respect to light having a wavelength of 700 nm, the film thickness (d / μm) in the photosensitive layer, and the concentration of oxotitanyl phthalocyanine in the photosensitive layer ( / Wt%) and, but is an image forming apparatus 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 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C. except for the peak accompanying vaporization of adsorbed water.
That is, the exposure memory can be effectively suppressed when the photosensitive layer satisfies the predetermined range of the characteristic represented by the relational expression (1) and the ionization potential.
Further, the exposure memory can be more effectively suppressed by making the difference between the ionization potential values of the charge generating agent and the hole transporting agent used 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.

[First Embodiment]
The first embodiment of the present invention is 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. In addition, oxo titanyl phthalocyanine having a Y-type crystal structure and having the following characteristics (b) is used as a charge generator , and oxo titanyl is used as a hole transport agent from the value of ionization potential (eV) in the hole transport agent. Reflection absorbance for light having a wavelength of 700 nm in the photosensitive layer using a hole transport agent having a value obtained by subtracting the ionization potential (eV) in phthalocyanine within a range of 0.1 to 0.4 (eV). (A / −), the film thickness (d / m) in the photosensitive layer, and the concentration (C / wt%) of oxotitanyl phthalocyanine in the photosensitive layer satisfy the following relational expression (1). An electrophotographic photosensitive member characterized by the above.
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 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C. except for the peak accompanying vaporization of adsorbed water.
Hereinafter, the electrophotographic photosensitive member of the first 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 by containing oxotitanyl phthalocyanine as a charge generating agent, a hole transport agent, an electron transport agent, and a binder resin in the same layer.
The reason for this is that by containing both a hole transport agent and an electron transport agent in the same photosensitive layer, the charge generated from oxo titanyl phthalocyanine as a charge generating agent at the time of exposure can be efficiently transported. It is because it can do.
Further, as shown in FIG. 1B, a photoconductor 10 ′ in which a barrier layer 16 is formed between the conductive substrate 12 and the photoconductive layer 14 within a range not impairing the characteristics of the photoconductor may be used. 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 photoreceptor according to the present invention, oxo titanyl phthalocyanine 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 type.
In addition, as a specific example of the oxo titanyl phthalocyanine represented by the general formula (1), a compound represented by the following formula (2) can be exemplified.

(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.

Further, the crystal form of oxotitanyl phthalocyanine is Y-type.
This is because such a Y-type oxotitanyl phthalocyanine improves the quantum yield in the charge generating agent, thereby improving 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 property and thermal property It is preferable to contain oxo titanyl phthalocyanine having the following property (b) as a charge generator.
(B) In the differential scanning calorimetry, it has no peak in the range of 50 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C., except for the peak accompanying vaporization of adsorbed water.
The reason for this is that with such a configuration, the aging stability and dispersibility of oxotitanyl phthalocyanine in the photosensitive layer coating solution can be further improved.

Further, when oxo titanyl phthalocyanine 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), such oxotitanyl phthalocyanine can suppress crystal transition in an organic solvent and exhibits particularly excellent dispersibility in a photosensitive layer coating solution. be able to.
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 oxotitanyl phthalocyanine and the charge transport agent, thus preventing the generation of residual potential in the photosensitive layer and effective exposure memory. Can be suppressed.

Moreover, it is preferable to contain further oxo titanyl phthalocyanine other than the oxo titanyl phthalocyanine which has the characteristic of (b) as a charge generating agent.
The reason for this is that oxo titanyl phthalocyanine which does not have the characteristics of (b) alone may have poor stability over time and dispersibility in the coating solution for the photosensitive layer, but oxo titanyl which has the characteristics of (b). This is because the problem is remarkably improved by combining with phthalocyanine.
That is, as long as a predetermined amount of the oxotitanyl phthalocyanine having the characteristic (b) is used, even the conventional oxotitanyl phthalocyanine having the characteristic (b) can be suitably used in combination. Therefore, by using oxo titanyl phthalocyanine having a plurality of characteristics as a charge generating agent in this way, it is 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 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 °. Don't do it.
This is because, when oxotitanyl phthalocyanine has the characteristic (c), the oxotitanyl phthalocyanine can more reliably control the crystal transition in an organic solvent.
That is, even when oxotitanyl phthalocyanine is actually immersed in an organic solvent such as tetrahydrofuran for 24 hours, it can be confirmed that the crystal form does not transfer to the α or β form and the Y form is maintained. Therefore, the crystal transition in the organic solvent can be reliably controlled.
In addition, the measuring method of the optical characteristic in oxo titanyl phthalocyanine and a thermal characteristic is described in a subsequent 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.
Note that a method for measuring the ionization potential will be described in a later example.

(4) Addition amount The addition amount of oxo titanyl phthalocyanine as a charge generating agent is preferably set to a value within the range of 0.6 to 3.0% by weight with respect to the total amount.
The reason for this is that by setting the amount of oxotitanyl phthalocyanine to a value within such a range, the oxo titanyl phthalocyanine can efficiently generate charges when exposed to a photoconductor, and charge transport can be performed. This is because charge transport to and from the agent is also efficiently performed.
That is, when the amount of oxotitanyl phthalocyanine added is less than 0.6% by weight, the amount of charge generation becomes insufficient, and it may be 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) Ionization Potential Further, as the hole transport agent, the ion transport potential (eV) of the hole transport agent is preferably set to a value within the range of 5.1 to 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 oxotitanyl phthalocyanine 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.

In addition, as a hole transport agent, a value obtained by subtracting a value of ionization potential (eV) in oxotitanylphthalocyanine from a value of ionization potential (eV) in the hole transport agent is in a range of 0.1 to 0.4 (eV). A hole transporting agent having a value within the range is used.
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 oxotitanylphthalocyanine, the photosensitive layer is used. This is because, in addition to the suppression of exposure memory and the improvement of sensitivity, the charging characteristics can be improved.
That is, when the difference between the ionization potential (eV) of such a hole transport agent and the ionization potential (eV) of oxotitanyl phthalocyanine is less than 0.1 eV, the ionization potential of the hole transport agent and the ionization of oxo titanyl phthalocyanine This is because the difference between the potential and the potential becomes excessively small, and the charging characteristics of the photosensitive member may deteriorate.
On the other hand, when the difference between the ionization potential (eV) of the hole transport agent and the ionization potential (eV) of oxotitanylphthalocyanine exceeds 0.4 eV, efficient charge transport becomes difficult, and the sensitivity This is because there is a case where the image quality decreases or an exposure memory is generated.
Therefore, the difference between the ionization potential (eV) of the hole transport agent and the ionization potential (eV) of oxotitanyl phthalocyanine is more preferably set to a value within the range of 0.12 to 0.35 eV. More preferably, the value is in the range of -0.3 eV.
In addition, the measuring method of the ionization potential in a hole transport agent is described in a later Example.

(2) Kinds Specific examples of the hole transport agent that satisfies the above-described conditions include hole transport agents (HTM-A to D) represented by the following formulas (3) to (6).

(3) Addition amount The addition amount of the hole transport 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 (7) to (10).

(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 (11).

6). Other additives In addition to the above-mentioned components, various additives such as a sensitizer, a fluorene compound, an ultraviolet absorber, a plasticizer, a surfactant, and a leveling agent are added to the photosensitive layer. You can also. 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, and the oxotitanyl phthalocyanine concentration (C / wt%) in the photosensitive layer are as follows. It satisfies the 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 oxotitanyl phthalocyanine as a 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) can be regarded as a parameter representing the dispersibility of oxotitanyl phthalocyanine in the photosensitive layer according to the Lambert-Beer law. it can.
That is, when the film thickness (d / m) and oxo titanyl phthalocyanine concentration (C / wt%) in the photosensitive layer are constant, if the dispersibility of oxo titanyl phthalocyanine is insufficient, incident light is hardly absorbed, and the wavelength is 700 nm. This is because the reflected absorbance (A) with respect to light tends to be small. On the other hand, if the dispersibility of oxotitanyl phthalocyanine 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 oxotitanyl phthalocyanine 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. 2, the numerical value of the left side A · C ⁻¹ · d ⁻¹ in the relational expression (1) (unit: 1 / (m · weight%), the same applies hereinafter) and the photoconductor. The relationship with the exposure memory potential will be described.
Here, FIG. 2 is a characteristic curve in which 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 exposure memory potential (V) of the photosensitive member. .
As can be understood from FIG. 2, 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. The value of the exposure memory potential (V) decreases as the value of the left side A · C ⁻¹ · d ⁻¹ in 1) increases from 1 × 10 ⁴ . 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 exposure memory potential (V) is reduced. 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 exposure memory potential (V) is almost stable at a value around 100 (V). It is understood that
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 titanyl phthalocyanine 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 reflection absorbance value with respect to light having a wavelength of 700 nm in the photosensitive layer is less than 0.7, the amount of oxotitanyl phthalocyanine added in the photosensitive layer is too small, and the amount of charge generation 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 value of the oxo titanyl phthalocyanine concentration in the photosensitive layer becomes excessively large. This is because it may not be possible to evaluate the dispersibility of oxotitanyl phthalocyanine in the photosensitive layer using 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. By adjusting the value of reflection absorbance (A / −) and the value of oxotitanyl phthalocyanine concentration (C / wt%) in the photosensitive layer, it is easy to form a photosensitive layer having characteristics satisfying the relational expression (1). It is to become. 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 forming a single layer type step back by a coating method, oxo titanyl phthalocyanine as a charge generating agent, a hole transport agent, an electron transport agent, a binder resin and the like together with a suitable solvent, a known method, For example, a dispersion 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 type photosensitive layer containing a binder resin, and as a charge generating agent, an oxotitanyl phthalocyanine having a Y-type crystal structure and having the following characteristics (b) is used as a hole transporting agent: A hole whose value obtained by subtracting the ionization potential (eV) value of oxotitanyl phthalocyanine from the ionization potential (eV) value of the hole transport agent is a value within the range of 0.1 to 0.4 (eV). Reflective absorbance (A /-) for light having a wavelength of 700 nm in the photosensitive layer using a transport agent, film thickness (d / μm) in the photosensitive layer, and oxotitanyl phthalocyanine in the photosensitive layer And degrees (C / wt%), but with satisfying the following relationships (1), an image forming apparatus characterized by exposing the electrophotographic photoreceptor is one.
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 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C. except for the peak accompanying vaporization of adsorbed water.
Hereinafter, the contents 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. 3 is preferably used.
Here, FIG. 3 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 toner image is transferred 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 of the present invention. .

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 generating agent, oxotitanyl phthalocyanine having a Y-type crystal structure and having the following characteristics (b) is used, and as a hole transporting agent, the value of ionization potential (eV) in the hole transporting agent is used in oxotitanyl phthalocyanine. Reflection absorbance of light with a wavelength of 700 nm in the photosensitive layer using a hole transporting agent having a value obtained by subtracting the ionization potential (eV) in the range of 0.1 to 0.4 (eV). A / −), the film thickness (d / μm) in the photosensitive layer, and the concentration (C / wt%) of oxotitanyl phthalocyanine in the electrophotographic photoreceptor in the photosensitive layer And satisfies 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 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C. except for the peak accompanying vaporization of adsorbed water.
Therefore, as described in detail in the first embodiment, the photoconductor 111 effectively suppresses the exposure memory and has excellent sensitivity during 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 Y-type oxotitanyl phthalocyanine (TiOPc) represented by formula (2) having an ionization potential of 5.25 eV, and having the characteristics represented by (TiOPc-A) in Table 1. Type oxo titanyl phthalocyanine 3 parts by weight, hole transporting agent (HTM-A) represented by the formula (3) 45 parts by weight, electron transporting agent (ETM-C) represented by the formula (9) 30 parts by weight And 100 parts by weight of Z-type polycarbonate (Resin-A) represented by the formula (11) having a viscosity average molecular weight of 20,000 as a binder resin (TS2020 manufactured by Teijin Chemicals Ltd.) A coating solution for the photosensitive layer was prepared by mixing and dispersing for 50 hours with tetrahydrofuran using a ball mill.
Next, this photosensitive layer coating solution was applied by dip coating to an aluminum drum-shaped support having a diameter of 30 mm and a total length of 254 mm as a conductive substrate. 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とＢは、それぞれ特許第３４６３０３２号に記載の方法で作成した。
ＴｉＯＰｃ−Ｃは実施例６に記載の方法で作成した。

TiOPc-A and B were prepared by the method described in Japanese Patent No. 34630 3 2, respectively.
TiOPc-C was prepared by the method described in Example 6.

2. Ionization potential measurement and DSC measurement (1) Ionization potential measurement The ionization potentials of the oxotitanyl phthalocyanine and hole transporting agent used were the atmospheric-type ultraviolet photoelectron analyzer (manufactured by Riken Keiki Co., Ltd., AC-1). It measured using. The results obtained are shown in Table 2.

(2) DSC measurement Moreover, DSC (differential scanning calorimetry) of the used oxo titanyl phthalocyanine was performed using a differential scanning calorimeter (TAS-200 type, DSC8230D manufactured by Rigaku Corporation). The measurement conditions are as follows. FIG. 4 shows the obtained differential scanning calorimetry analysis 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.
More specifically, FIGS. 5A and 5B will be described in more detail. FIG. 5A shows a state in which 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. 5A and 5B, I ₀ represents the intensity of light (incident light) irradiated to each support substrate, and I ₁ and I ₂ represent the respective support 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, based on the obtained values of reflected absorbance (A ₁ , A ₂ ), the reflected absorbance (A) of the intermediate layer is calculated from the following formula (1), and the reflected absorbance (A) is calculated as follows: In light of the criteria, the dispersibility of oxotitanyl phthalocyanine particles in the photosensitive layer was evaluated. The obtained results are shown in Table 1.
The reflected absorbance (A ₁ ) in FIG. 5 (a) is calculated from the following formula (2). Similarly, the reflected absorbance (A ₂ ) in FIG. 5 (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, the dispersibility of oxotitanyl phthalocyanine in the photosensitive layer is high. The reflection absorbance A of the photosensitive layer in Example 1 was 0.0810.
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 static elimination lamp is omitted, and after printing 1000 sheets of a 5% density character original, an unexposed portion (white paper in a formed image) The surface potential of the exposed portion (corresponding to the black solid portion in the formed image) after the charging step 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 100 (V).
○: The memory potential is a value less than 100 to 110 (V).
Δ: The memory potential is a value less than 110 to 120 (V).
X: Memory potential is a value of 120 (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.) in which a static elimination lamp was 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. 6 was used, and it was determined whether a ghost image of a solid black portion was generated 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 100 (V).
◯: The sensitivity value is 101 (V) or more and less than 150 (V).
X: The value of sensitivity is 151 (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 x.
X: At least one evaluation of x is received in all items.

[Reference Examples 2 to 5 and 7, Example 6]
In Reference Examples 2 to 5 and 7, and Example 6 , the Y-type oxotitanyl phthalocyanine (TiOPc-A) used in Reference Example 1 and the hole represented by the formula (3) were used in the production of the photoreceptor. Instead of the transport agent (HTM-A), as shown in Table 2, Y-type oxotitanyl phthalocyanine (TiOPc-A to D) and a hole transport agent (HTM) represented by formulas (3) to (6), respectively. A photosensitive member was produced and evaluated in the same manner as in Example 1 except that -AD) were used. The obtained results are shown in Table 2.
The characteristics of each Y-type oxotitanyl phthalocyanine are shown in Table 1.

1. CuKα Characteristic X-ray Diffraction Spectrum Measurement Here, the CuKα characteristic X-ray diffraction spectrum of Y-type oxotitanyl phthalocyanine (TiOPc-B) used in Example 5 was measured by the following measurement method.
First, 0.3 g of Y-type oxotitanyl phthalocyanine 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. Measurement was performed by filling a sample holder of RINT1100) manufactured by Rigaku Denki Co., Ltd. The obtained X-ray spectrum is shown in FIG.
Measurement conditions were as follows.
X-ray tube: Cu
Tube voltage: 40 kV
Tube current: 30 mA
Start angle: 3.0 °
Stop angle: 40.0 °
Scanning speed: 10 ° / min

2. Production of Y-type oxo titanyl phthalocyanine (TiOPc-C) The production method of Y-type oxo titanyl phthalocyanine (TiOPc-C) used in Example 6 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, and 2.28 g (0.038 mol) of urea The quinoline 300g was added and it heated up to 150 degreeC, 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 (2) -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 stirred. The mixture was heated to 130 ° C. and stirred 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) -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 the liquid was filtered off with a glass filter, the obtained solid was vacuum dried at 50 ° C. for 5 hours to obtain 4.1 g of unsubstituted titanyl phthalocyanine crystals (blue powder) represented by the formula (3). Got.
In addition, the differential scanning calorimetry of Y-type oxotitanyl phthalocyanine (TiOPc-C) used in Example 6 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, the Y-type oxotitanyl phthalocyanine (TiOPc-A) used in Example 1 and the hole transporting agent (HTM-A) represented by the formula (3) were used in the production of the photoreceptor. ), Y-type oxotitanyl phthalocyanine (TiOPc-F) and hole transporting agents (HTM-A to B) represented by formulas (3) to (4) were used as shown in Table 2, respectively. Otherwise, the photoreceptors were produced 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 used are shown in Table 1.

[Comparative Example 3]
In Comparative Example 3, it is represented by the following formula (12) 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-E) was used. The obtained results are shown in Table 2.

[Comparative Example 4]
In Comparative Example 4, it is represented by the following formula (13) 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-F) was used. The obtained results are shown in Table 2.

[Comparative Example 5]
In Comparative Example 5, 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 the photoreceptor is manufactured. 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 Examples 6-7]
In Comparative Examples 6 to 7, when manufacturing the photoconductor, the Y-type oxotitanyl phthalocyanine (TiOPc-A) used in Example 1 and the hole transporting agent (HTM-A) represented by the formula (3) were used. ) In place of Y-type oxo titanyl phthalocyanine (TiOPc-E) and hole transporting agents (HTM-A to B) represented by formulas (3) to (4) as shown in Table 2 respectively. Otherwise, the photoreceptors were produced 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 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 setting the characteristics of the generator and the hole transport agent within a predetermined range, 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 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 CuK (alpha) characteristic X-ray-diffraction spectrum of TiPc-B which is a charge generating agent. It is a figure which shows the chart in the differential scanning calorimetry of TiPc-C 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 (6)

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 generator , an oxotitanyl phthalocyanine having a Y-type crystal structure and having the following characteristics (b) is used :
As the hole transport agent, a value obtained by subtracting the ionization potential (eV) value in the oxotitanylphthalocyanine from the ionization potential (eV) value in the hole transport agent is in a range of 0.1 to 0.4 (eV). Use the hole transport agent that is the value of
And 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 in the photosensitive layer. An electrophotographic photosensitive member satisfying the following relational expression (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 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C. except for the peak accompanying vaporization of adsorbed water. 2. The electrophotographic photoreceptor according to claim 1, further comprising oxo titanyl phthalocyanine other than the oxo titanyl phthalocyanine having the characteristic (b) as the charge generating agent. 3. The electrophotographic photoreceptor according to claim 1, wherein the oxo titanyl phthalocyanine contains oxo titanyl phthalocyanine having the following characteristics (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 a Bragg angle 2θ ± 0.2 ° = 27.2 ° and a peak at 26.2 °. Don't do it.   The oxo titanyl phthalocyanine concentration (C / wt%) in the single-layer type photosensitive layer is set to a value in the range of 0.6 to 3.0 wt%. The electrophotographic photosensitive member described. 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 generator , an oxotitanyl phthalocyanine having a Y-type crystal structure and having the following characteristics (b) is used :
As the hole transport agent, a value obtained by subtracting the ionization potential (eV) value in the oxotitanylphthalocyanine from the ionization potential (eV) value in the hole transport agent is in a range of 0.1 to 0.4 (eV). Use the hole transport agent that is the value of
And, the reflection absorbance (A / −) for light having a wavelength of 700 nm in the photosensitive layer, the film thickness (d / μm) in the photosensitive layer, the concentration of oxotitanyl phthalocyanine in the photosensitive layer (C / wt%), Satisfies the following relational expression (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 ° C. to 200 ° C. but one peak in the range of 296 to 400 ° C. except for the peak accompanying vaporization of adsorbed water.   The image forming apparatus according to claim 5, wherein the image forming apparatus does not have a charge eliminating unit.

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