JP5405873B2 - Single layer type electrophotographic photosensitive member and image forming apparatus - Google Patents

Description

  The present invention relates to a single layer type electrophotographic photosensitive member and an image forming apparatus. In particular, the process speed is increased to a predetermined value or more, and even when the charging potential is set to a relatively high value, it exhibits excellent gas resistance, and as a result, a single layer that can maintain excellent charging stability The present invention relates to a type electrophotographic photosensitive member and an image forming apparatus.

2. Description of the Related Art Conventionally, an organic photoreceptor composed of a binder resin, a charge generator, a charge transport agent, and the like has been used as an electrophotographic photoreceptor used in an image forming apparatus. Such an organic photoreceptor is advantageous in that it is easy to manufacture and has a wide degree of freedom in structural design because it has various options for the photoreceptor material as compared with conventional inorganic photoreceptors.
On the other hand, when an organic photoreceptor is exposed to an oxidizing gas such as NOx or ozone generated mainly in the charging process, the material in the photosensitive layer is likely to chemically change, and as a result, the charging characteristics are likely to deteriorate. It was observed.

Therefore, in order to solve the problem of gas resistance in the photosensitive layer, a method of containing an antioxidant in the photosensitive layer is widely used (for example, Patent Document 1).
That is, Patent Document 1 discloses an electrophotographic photoreceptor in which a photosensitive layer contains a charge transport material having an ionization potential of 5.1 eV or less and an antioxidant.

JP 2007-72139 A

However, in the electrophotographic photosensitive member in Patent Document 1, the antioxidant is consumed as it is used. In particular, the process speed is set to a value exceeding 120 mm / sec, and the charging potential is relatively higher than 600 V. When it was set to a high value, there was a problem that it was difficult to maintain gas resistance for a long period of time.
On the other hand, when the blending amount of the antioxidant is increased, charging characteristics and mechanical property control are lowered, and new problems such as a decrease in image density and a decrease in durability are observed.

Therefore, as a result of intensive studies, the present inventors have determined that in a single-layer electrophotographic photosensitive member, the viscosity average molecular weight of the binder resin is not more than a predetermined value and a charge generating agent having a predetermined characteristic is used. It has been found that the gas resistance in the layer can be effectively improved.
That is, the object of the present invention is to improve the gas resistance even when the process speed is set to a high value above a predetermined value or the charging potential is set to a high value above a predetermined value. Accordingly, an object of the present invention is to provide a single-layer electrophotographic photosensitive member and an image forming apparatus having excellent charging stability and sensitivity characteristics.

According to the present invention, there is provided an electrophotographic photosensitive member mounted on an image forming apparatus having a charging potential value in a range of 600 to 1000 V and having a process speed exceeding 120 mm / sec. And a photosensitive layer containing at least a charge generating agent, a hole transporting agent, an electron transporting agent, and a binder resin, the viscosity average molecular weight of the binder resin being 29000 or less, and the binder resin being , Including only one type of polycarbonate resin selected from the following general formulas (1) to (2), the molecular weight of the electron transport agent is set to a value in the range of 300 to 502.6, and the molecular weight of the hole transport agent is 400. and a value within the range of 680, the charge generating agent, a single-layer type electrophotographic photoreceptor which is a titanyl phthalocyanine crystal having the following properties (a) and (B) are provided, the above-described It is possible to solve the problem point.
(A) The CuKα characteristic X-ray diffraction spectrum has main peaks at Bragg angles 2θ ± 0.3 ° = 9.5 and 27.2 °.
(B) In the differential scanning calorimetry spectrum, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
That is, in a single-layer type electrophotographic photosensitive member, even when the process speed is mounted on an image forming apparatus having a predetermined value or higher, or when the charging potential is mounted on an image forming apparatus having a predetermined value or higher, Excellent charging stability and sensitivity characteristics can be obtained.
More specifically, even in an environment where NOx and ozone gas are likely to be generated, excellent charge stability can be obtained by setting the viscosity average molecular weight of the binder resin to a predetermined value and using a charge generating agent having predetermined characteristics. And sensitivity characteristics can be obtained.
Moreover, the compatibility between the charge generating agent and the charge transporting agent can be improved by using such a binder resin.
As a result, it becomes difficult for the oxidizing gas to penetrate into the photosensitive layer, and the gas resistance in the photosensitive layer can be further improved.
Further, by using such an electron transfer agent, compatibility with the binder resin can be further improved, and predetermined durability can be maintained. Therefore, the invasion of the oxidizing gas to the photosensitive layer can be suppressed over a long period.
In addition, by using such a hole transport agent, compatibility with the binder resin can be further improved, and predetermined durability can be maintained. Therefore, the invasion of the oxidizing gas to the photosensitive layer can be suppressed over a long period.

(In the general formula (1), the plurality of substituents Ra and Rb are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts p and q are each independently an integer of 0 to 4, and the substituents Rc and Rd are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms. W is a single bond, —O—, —CO—, —CH ₂ —, and the subscripts k and l are molar ratios satisfying the relational expression of 0 <l / (k + 1) <0.6. .)

(In the general formula (2), the plurality of substituents Re and Rf are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts r and s are each independently an integer of 0 to 4, and the subscripts m and n are molar ratios satisfying a relational expression of 0 <n / (n + m) <0.6. And W is —O—, —CO—, or —CH ₂ —.)

In constituting the single-layer electrophotographic photosensitive member of the present invention, it is preferable that the oxotitanyl phthalocyanine crystal further has the following characteristic (C).
(C) In the CuKα characteristic X-ray spectrum, the ratio A / B between the peak intensity A at the Bragg angle 2θ ± 0.3 ° = 7.2 ° and the peak intensity B at 9.5 ° (hereinafter referred to as α degree) Is a value within the range of 0.05 to 0.25.
By using an oxotitanyl phthalocyanine crystal having such a characteristic (C), it is possible to obtain further excellent charging stability and sensitivity characteristics even in an environment where NOx and ozone gas are easily generated.
That is, if the oxo titanyl phthalocyanine crystal has a degree of alpha conversion within a predetermined range, the dispersibility can be further improved, and as a result, sensitivity characteristics and exposure memory characteristics can be effectively improved.

Another aspect of the present invention is an image forming apparatus having a charging unit, an exposing unit, a developing unit, and a transferring unit around the electrophotographic photosensitive member and having a process speed exceeding 120 mm / sec. The charging potential on the surface of the photographic photosensitive member is a value in the range of 600 to 1000 V, and the electrophotographic photosensitive member includes a charge generating agent, a hole transporting agent, an electron transporting agent and a binder resin on the substrate in the same layer. A single-layer electrophotographic photosensitive member having a photosensitive layer, wherein the binder resin has a viscosity average molecular weight of 29000 or less, and the binder resin is selected from the above general formulas (1) to (2) It includes types only of the polycarbonate resin, the molecular weight of the electron transport agent to a value within the range of 300 to 502.6, a molecular weight of the hole transport agent to a value within the range of 400 to 680, the charge generating agent, following JP An image forming apparatus which is a titanyl phthalocyanine crystal having (A) and the (B).
(A) The CuKα characteristic X-ray diffraction spectrum has main peaks at Bragg angles 2θ ± 0.3 ° = 9.5 and 27.2 °.
(B) In the differential scanning calorimetry spectrum, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
That is, by configuring the image forming apparatus in this way, even if the process speed is a predetermined value or more, the charging potential is a predetermined value or more, and a considerable amount of antioxidant is used. Even in the case of an electrophotographic photoreceptor that does not, excellent charging stability and sensitivity characteristics can be obtained.

In constituting the image forming apparatus of the present invention, the charging unit is preferably a non-contact type charging unit.
When configured in this way, although the amount of oxidizing gas generated in the charging step increases, in the present invention, since a predetermined single layer type electrophotographic photoreceptor excellent in gas resistance is mounted, Even when image formation is repeatedly performed without deteriorating the surface of the photosensitive layer, a high-quality image can be stably formed.

In configuring the image forming apparatus of the present invention, it is preferable that the image forming apparatus is an image forming apparatus of a simultaneous development cleaning system.
In such a configuration, generally, residual toner and foreign matter on the surface of the photosensitive layer are difficult to be cleaned. However, according to the present invention, a predetermined single-layer type electrophotographic photoreceptor excellent in gas resistance in the photosensitive layer is mounted. Therefore, even if residual toner or foreign matter remains on the surface of the photosensitive layer, the surface of the photosensitive layer is unlikely to deteriorate, so even when repeated image formation is performed, high-quality images are stably formed. can do.

FIG. 1 is a diagram provided for explaining the relationship between the viscosity average molecular weight of a polycarbonate binder resin and the gas resistance evaluation result. FIG. 2 is a diagram provided to explain the relationship between the degree of alpha conversion of the oxotitanyl phthalocyanine crystal and the sensitivity characteristics. FIG. 3 is a diagram provided for explaining the relationship between the degree of alpha conversion of the oxotitanyl phthalocyanine crystal and the exposure memory characteristics. FIGS. 4A to 4B are diagrams for explaining the configuration of the single-layer electrophotographic photosensitive member of the present invention. FIG. 5 is a diagram for explaining the configuration of the image forming apparatus of the present invention. FIG. 6 is a CuKα characteristic X-ray diffraction spectrum of the oxotitanyl phthalocyanine crystal used in Example 1 (after storage in tetrahydrofuran for 24 hours). 7 is a differential scanning calorimetry chart of the oxotitanyl phthalocyanine crystal used in Example 1. FIG.

[First Embodiment]
The first embodiment is an electrophotographic photosensitive member mounted on an image forming apparatus having a charging potential value in a range of 600 to 1000 V and a process speed exceeding 120 mm / sec. Further, a photosensitive layer containing at least a charge generator, a hole transport agent, an electron transport agent, and a binder resin is provided. The viscosity average molecular weight of the binder resin is equal to or less than 29000. with a value, the binder resin comprises only one type of polycarbonate resin selected from the later-described general formulas (1) to (2), within the range of the molecular weight of the electron transport agent 300 to 502.6 and then, the molecular weight of the hole transport agent to a value within the range of 400 to 680, the charge generating agent, a single-layer type photoelectric which is a titanyl phthalocyanine crystal having the following properties (a) and (B) It is a photosensitive member.
(A) The CuKα characteristic X-ray diffraction spectrum has main peaks at Bragg angles 2θ ± 0.3 ° = 9.5 and 27.2 °.
(B) In the differential scanning calorimetry spectrum, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
That is, as shown in FIG. 1, by using a binder resin having a predetermined viscosity average molecular weight together with an oxo titanyl phthalocyanine crystal having predetermined characteristics (A) and (B), excellent gas resistance characteristics, etc. Can be obtained.
Further, as shown in FIGS. 2 and 3, by using an oxotitanyl phthalocyanine crystal having a predetermined characteristic (C) with respect to a predetermined crystallinity (α conversion), further excellent sensitivity and memory potential can be obtained. be able to.
Hereinafter, the single layer type electrophotographic photosensitive member as the first embodiment will be described in detail for each component.
The single-layer type electrophotographic photosensitive member of the present invention is mounted on an image forming apparatus having a charging potential in the range of 600 to 1000 V when charging the single-layer type electrophotographic photosensitive member. However, this configuration requirement will be specifically described in the second embodiment.

1. Basic Structure The electrophotographic photosensitive member 10 of the present invention is a single-layer type photosensitive layer comprising a base 12 and a charge generating agent, a charge transporting agent, and a binder resin as shown in FIG. 14 is a single-layer type electrophotographic photosensitive member 10 provided with 14.
Further, as illustrated in FIG. 4B, a single-layer electrophotographic photosensitive member 10 ′ in which an intermediate layer 16 is formed between the photosensitive layer 14 and the substrate 12 can be used.

2. Substrate Moreover, various materials can be used as the constituent material of the substrate.
For example, a substrate formed of a metal such as iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, or the above-described metal is deposited or deposited. Examples include a substrate made of a laminated plastic material, or a glass substrate coated with aluminum iodide, alumite, tin oxide, indium oxide, or the like.
That is, it is sufficient that the substrate itself has conductivity, or the surface of the substrate has conductivity, and it is sufficient that the substrate has sufficient mechanical strength when used.

3. Intermediate Layer Further, as shown in FIG. 4B, an intermediate layer 16 containing a predetermined binder resin may be provided on the base 12.
This is because the adhesion between the substrate and the photosensitive layer is improved, and a predetermined fine powder is added to the intermediate layer to scatter incident light and suppress the generation of interference fringes. This is because it is possible to suppress charge injection from the substrate to the photosensitive layer during non-exposure causing black spots. The fine powder is not particularly limited as long as it has light scattering properties and dispersibility, and examples thereof include white pigments such as titanium oxide, zinc oxide, zinc white, zinc sulfide, lead white, and lithopone. Inorganic pigments such as alumina, calcium carbonate, barium sulfate and the like, fluorine resin particles, benzoguanamine resin particles, styrene resin particles, and the like can be used.

Moreover, it is preferable to make the film thickness of this intermediate | middle layer into the value within the range of 0.1-50 micrometers. This is because if the intermediate layer is too thick, a residual potential is likely to be generated on the surface of the photoreceptor, which may cause a decrease in electrical characteristics. On the other hand, if the thickness of the intermediate layer becomes too thin, the unevenness of the surface of the substrate cannot be sufficiently relaxed, and the adhesion between the substrate and the photosensitive layer may not be obtained.
Therefore, the thickness of the intermediate layer is preferably set to a value in the range of 0.1 to 50 μm, and more preferably set to a value in the range of 0.5 to 30 μm.

4). Photosensitive layer
(1) Binder resin
The kind of the binder resin used for the electrophotographic photoreceptor of the present invention is characterized by including a polycarbonate resin represented by at least one general formula selected from the following general formulas (1) to (2) .

(In the general formula (1), the plurality of substituents Ra and Rb are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts p and q are each independently an integer of 0 to 4, and the substituents Rc and Rd are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms. W is a single bond, —O—, —CO—, —CH ₂ —, and the subscripts k and l are molar ratios satisfying a relational expression of 0 <l / (k + 1) <0.6. .)

(In the general formula (2), the plurality of substituents Re and Rf are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts r and s are each independently an integer of 0 to 4, and the subscripts m and n are molar ratios satisfying a relational expression of 0 <n / (n + m) <0.6. And W is —O—, —CO—, or —CH ₂ —.)

This is because these polycarbonate resins can improve the compatibility with the charge generating agent and the charge transporting agent.
As a result, it is difficult for the oxidizing gas to penetrate into the photosensitive layer, and the gas resistance in the photosensitive layer can be further improved.
In addition, as a substituent in the substituent shown in General formula (1)-(2), a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C6-C30 aryl group, etc. are mentioned. .
In addition, the subscripts k to n in the general formulas (1) and (2) represent the molar ratio of the copolymerization component. For example, when k is 85 and l is 15, the molar ratio is 85:15. Represents. Such a molar ratio can be calculated by, for example, NMR.

Here, specific examples of the polycarbonate resin represented by the general formula (1) include polycarbonate resins (Resin-1 to 6 ) represented by the following formulas (3) to (8) (formula (9)). (Resin-7) is a reference example).
That is, as shown in the following formula, the polycarbonate resin represented by the general formula (1) is more preferably one in which the substituent Rc is a hydrogen atom and the substituent Rd is an alkyl group having 1 to 2 carbon atoms. More preferably, the substituent Rd is a methyl group.
This is because the compatibility of the binder resin with the charge generating agent and the charge transporting agent can be further improved by doing so.

Moreover, as a reference example of polycarbonate resin represented by General formula (2), the polycarbonate resin (Resin-8-9) represented by following formula (10)-(11) can be mentioned.

Further, the viscosity average molecular weight of the binder resin is set to a value of 29,000 or less .
This is because when the viscosity average molecular weight of the binder resin exceeds 29,000 , the compatibility between the binder resin, the charge generator and the charge transport agent is excessively reduced, and the oxidizing gas is reduced. This is because it easily penetrates into the photosensitive layer and it becomes difficult to maintain a predetermined gas resistance.
However, when the viscosity average molecular weight of the binder resin is excessively small, the mechanical strength of the photosensitive layer may be significantly reduced.
Therefore, the viscosity average molecular weight of the binder resin is more preferably set to a value within the range of 15,000 to 29,000, and further preferably set to a value within the range of 20,000 to 28,000.

Here, the relationship between the viscosity average molecular weight of the polycarbonate binder resin and the gas resistance evaluation result will be described with reference to FIG.
That is, the horizontal axis of FIG. 1 shows the viscosity average molecular weight of the polycarbonate binder resin, and the vertical axis of FIG. 1 shows the gas resistance evaluation result (V).
As shown in the characteristic curve of FIG. 1, there is a tendency that the gas resistance evaluation result (V) becomes better as the viscosity average molecular weight of the polycarbonate binder resin becomes smaller.
Therefore, when the viscosity average molecular weight of the polycarbonate binder resin is 29,000 or less , the gas resistance evaluation result (V) can be improved.

(2) Charge generator The charge generator used in the electrophotographic photosensitive member of the present invention includes crystals of an oxotitanyl phthalocyanine compound represented by the following formula (12).

  This is because such an oxotitanyl phthalocyanine crystal can further improve the compatibility between the binder resin and the charge generating agent.

The oxotitanyl phthalocyanine crystal has a main peak at a Bragg angle 2θ ± 0.2 ° = 27.2 ° in the CuKα characteristic X-ray diffraction spectrum as the characteristic (A) (first optical characteristic). ).
In the CuKα characteristic X-ray diffraction spectrum, it is preferable that there is no peak at the Bragg angle 2θ ± 0.2 ° = 26.2 ° (second optical characteristic).
Furthermore, in the CuKα characteristic X-ray diffraction spectrum, it is preferable that there is no peak at the Bragg angle 2θ ± 0.2 ° = 7.2 ° (third optical characteristic).
These reasons are that, when the first optical characteristic is not provided, the crystal stability, charge generation ability and dispersibility tend to be remarkably lowered as compared with the oxotitanyl phthalocyanine crystal having such an optical characteristic. Because there is. In other words, it is possible to improve crystal stability, charge generation ability and dispersibility by providing the first optical characteristic, more preferably the second optical characteristic and the third optical characteristic. .

Further, the oxotitanyl phthalocyanine crystal has one peak in the range of 270 to 400 ° C. as a characteristic (B) in the differential scanning calorimetric analysis other than the peak accompanying vaporization of adsorbed water.
This is because the oxo titanyl phthalocyanine crystal having such optical characteristics and thermal characteristics can further improve crystal stability, charge generation ability and dispersibility.
In addition, it is more preferable that one peak appearing in the range of 270 to 400 ° C. other than the peak accompanying vaporization of the adsorbed water appears in the range of 290 to 400 ° C., and the range of 300 to 400 ° C. More preferably, it appears within.

Moreover, it is preferable that an oxo titanyl phthalocyanine crystal has the following characteristic (C).
(C) In the CuKα characteristic X-ray spectrum, the ratio A / B between the peak intensity A at Bragg angle 2θ ± 0.3 ° = 7.2 ° and the peak intensity B at 9.5 ° is 0.05 to It is a value within the range of 0.25.
This is because, when the ratio A / B is set to a value of 0.25 or less, the crystal transition to the α-type is difficult, and the specific crystal form can be more stably maintained. That is, even in an environment where NOx and ozone gas are likely to be generated, it is possible to obtain further excellent charging stability and sensitivity characteristics, and further improve the exposure memory characteristics.
On the other hand, setting the ratio A / B to a value less than 0.05 is more preferable from the viewpoint of suppressing crystal transition to α-type, but the yield during production may be excessively reduced. .
Therefore, the ratio A / B is more preferably a value within the range of 0.1 to 0.25, and even more preferably a value within the range of 0.15 to 0.20.

Here, with reference to FIGS. 2 and 3, the relationship between the degree of alpha (A / B) of the oxotitanyl phthalocyanine crystal, the sensitivity characteristic, and the exposure memory characteristic will be described in detail.
The horizontal axis of FIG. 2 shows the degree of alpha (A / B) (−), and the vertical axis shows the characteristic curve taking the sensitivity (relative value).
In FIG. 3, the abscissa indicates the degree of alpha (A / B) (−), and the ordinate indicates the memory potential (relative value) and the characteristic curve.
From the characteristic curves shown in FIG. 2 and FIG. 3, as the alpha value (A / B) of the oxotitanyl phthalocyanine crystal gradually increases, the sensitivity and the memory potential also increase. It is understood that there is a correlation.
More specifically, from these characteristic curves, the sensitivity and memory potential are stably maintained at a predetermined value or less by suppressing the value of the degree of alpha (A / B) to a range of 0.25 or less. can do.
In addition, the sensitivity and the memory potential can be held at lower values by suppressing the value of the degree of alpha (A / B) to a range of 0.22 or less.
That is, from the results shown in FIG. 2 and FIG. 3, by setting the value of the degree of alpha (A / B) within a predetermined range, dispersibility of the oxotitanyl phthalocyanine crystal in the photosensitive layer, crystal stability in the organic solvent, It is understood that various characteristics such as charge generation ability are effectively exhibited.

In addition, the alpha degree (A / B) of an oxo titanyl phthalocyanine crystal | crystallization can be suitably adjusted according to the following manufacturing process, for example.
(A) Step of obtaining a titanyl phthalocyanine solution by dissolving a crude titanyl phthalocyanine crystal in an acid to obtain a titanyl phthalocyanine solution in a poor solvent to obtain a wet cake (c) Step (d) of washing with alcohol of No. 4 (d) Step of obtaining an initial titanyl phthalocyanine crystal by heating and stirring the washed wet cake in a non-aqueous solvent (e) Obtaining the initial titanyl phthalocyanine crystal from 1 to 4 carbon atoms (F) After washing the initial titanyl phthalocyanine crystal after finely pulverizing, stirring and heating in a non-aqueous solvent to obtain a titanyl phthalocyanine crystal (g) Step of washing with alcohols of formulas 1 to 4 That is, in step (d), non-water After washing the initial titanyl phthalocyanine crystal obtained by stirring in a system solvent with a predetermined alcohol, in the step (f), after further pulverizing and further stirring in a non-aqueous solvent, The electrical conductivity can be efficiently set to a value within a predetermined range.
The degree of alpha (A / B) of the oxotitanyl phthalocyanine crystal is determined by, for example, adding 0.3 g of oxo titanyl phthalocyanine crystal to 20 g of water and ultrasonically dispersing for 90 seconds in an environment of 23 ± 3 ° C. ( (Frequency: 18 kHz) By controlling the value of the electric conductivity in the filtrate of the dispersion obtained by performing the treatment in the range of 0.6 to 2.4 μS / cm, it can be controlled and confirmed.

In order to obtain an oxotitanyl phthalocyanine crystal having the above-mentioned optical properties and thermal properties, when synthesizing an oxo titanyl phthalocyanine compound, the amount of titanium alkoxide such as titanium tetrabutoxide or titanium tetrachloride as a material substance is added. In addition, o-phthalonitrile or a derivative thereof as another material, or 1,3-diiminoisoindoline or a derivative thereof may be set to a value within a range of 0.40 to 0.53 mol. Preferably, the value is in the range of 0.42 to 0.50 mol.
Furthermore, it is preferable to synthesize the oxotitanyl phthalocyanine compound in the presence of the urea compound. In this case, the amount of the urea compound added is o-phthalonitrile or a derivative thereof, or 1,3-diiminoisoindoline. Or it is preferable to set it as the value within the range of 0.1-0.95 mol with respect to 1 mol of its derivatives, and it is more preferable to set it as the value within the range of 0.2-0.8 mol.

Moreover, it is preferable to make the addition amount of a charge generator into the value within the range of 0.2-40 weight part with respect to 100 weight part of binder resin.
The reason for this is that when the amount of the charge generator added is less than 0.2 parts by weight, the effect of increasing the quantum yield becomes insufficient, and the sensitivity characteristics, electrical characteristics, stability, etc. of the electrophotographic photoreceptor are improved. It is because it becomes impossible. On the other hand, when the amount of the charge generator added exceeds 40 parts by weight, the effect of increasing the extinction coefficient for light having a wavelength in the red region, near infrared region, or infrared region in visible light becomes insufficient. This is because the sensitivity characteristics, electrical characteristics, stability, and the like of the photoconductor may not be improved.
Therefore, the amount of the charge generator added is more preferably in the range of 0.5 to 20 parts by weight, and still more preferably in the range of 1 to 10 parts by weight.

(3) Electron transport agent The electron transport agent used in the electrophotographic photosensitive member of the present invention is not particularly limited. For example, diphenoquinone derivatives, naphthoquinone derivatives, benzoquinone derivatives, dinaphthoquinone derivatives, Anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, thioxanthone derivatives, fluorenone derivatives, anthracene derivatives, acridine derivatives, antharaquinone derivatives, anthraquinone derivatives, tetracyanoethylene, thioxanthone derivatives, nitrobenzene derivatives, acridine derivatives, succinic anhydride, maleic anhydride, One kind of a compound having an electron accepting property such as dibromomaleic anhydride or a combination of two or more kinds may be mentioned.

Further, the number average molecular weight of the electron transfer agent is set to a value in the range of 300 to 502.6 .
This is because, by setting the number average molecular weight of the electron transporting agent in such a range, the compatibility between the binder resin and the electron transporting agent can be further improved, and the fineness of the photosensitive layer can be reduced. This is because the entry of the oxidizing gas to the photosensitive layer can be effectively suppressed.
That is, when the molecular weight of the electron transport agent is less than 300, compatibility with the binder resin can be improved, but it may be difficult to obtain sufficient electron transport ability. On the other hand, when the molecular weight of the electron transfer agent exceeds 502.6 , the compatibility with the binder resin is lowered, the texture of the photosensitive layer becomes rough, and as a result, an oxidizing gas easily enters the photosensitive layer. This is because there may be cases.
Therefore, the molecular weight of the electron transfer agent is more preferably set to a value within the range of 300 to 500, and further preferably set to a value within the range of 300 to 400.

Moreover, it is preferable to make the addition amount of an electron carrying agent into the value within the range of 10-100 weight part with respect to 100 weight part of binder resin.
This is because when the amount of the electron transport agent added is less than 10 parts by weight, the sensitivity is lowered and a practical problem may occur. On the other hand, if the amount of the electron transport agent added exceeds 100 parts by weight, crystallization may be easily caused.
Therefore, it is more preferable to set the addition amount of the electron transport agent to a value within the range of 20 to 80 parts by weight, and to a value within the range of 30 to 70 parts by weight with respect to 100 parts by weight of the binder resin. Further preferred.

(4) Hole transport agent The hole transport agent used in the electrophotographic photosensitive member of the present invention is not particularly limited, and examples thereof include benzidine compounds, phenylenediamine compounds, and naphthylenediamine compounds. Compounds, phenanthrylenediamine compounds, oxadiazole compounds (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, etc.), styryl compounds (eg, 9- ( 4-diethylaminostyryl) anthracene), carbazole compounds (eg, poly-N-vinylcarbazole, etc.), organic polysilane compounds, pyrazoline compounds (eg, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, etc.) Hydrazone compounds, triphenylamine compounds, indole compounds, oxy Sazole compound, isoxazole compound, thiazole compound, thiadiazole compound, imidazole compound, pyrazole compound, triazole compound, butadiene compound, pyrene-hydrazone compound, acrolein compound, carbazole-hydrazone compound, quinoline A hydrazone compound, a stilbene compound, a stilbene-hydrazone compound, a diphenylenediamine compound, or the like is preferably used. These may be used alone or in combination of two or more.

Further, the molecular weight of the hole transporting agent is set to a value in the range of 400 to 680 .
This is because the compatibility of the binder resin and the hole transport agent can be further improved by making the molecular weight of the hole transport agent within such a range, and the texture of the photosensitive layer can be made finer. This is because the penetration of the oxidizing gas into the photosensitive layer can be further effectively suppressed.
That is, when the molecular weight of the hole transport agent is less than 400, compatibility with the binder resin can be improved, but it may be difficult to obtain sufficient hole transport ability. On the other hand, when the molecular weight of the hole transport agent exceeds 680, the compatibility with the binder resin is lowered, the texture of the photosensitive layer becomes rough, and the oxidizing gas easily enters the photosensitive layer. This is because there are cases.
Therefore, the molecular weight of the hole transport agent is more preferably set to a value within the range of 400 to 680, and further preferably set to a value within the range of 450 to 650.

Moreover, it is preferable to make the addition amount of a positive hole transport agent into the value within the range of 10-100 weight part with respect to 100 weight part of binder resin.
The reason for this is that by setting the content of the hole transporting agent in such a range, excellent electrical characteristics can be obtained while effectively suppressing the crystallization of the hole transporting agent in the photosensitive layer. This is because it can.
That is, when the content of the hole transport agent is less than 10 parts by weight, the sensitivity is lowered, and there may be practical problems. On the other hand, when the content of the hole transport agent exceeds 100 parts by weight, the hole transport agent is excessively easily crystallized and it is difficult to form an appropriate film as a photosensitive layer. Because there is.
Therefore, the content of the hole transport agent is more preferably set to a value within the range of 20 to 90 parts by weight, and further preferably set to a value within the range of 30 to 80 parts by weight.

(5) Film thickness The thickness of the photosensitive layer is preferably set to a value in the range of 5 to 100 μm.
This is because if the thickness of the photosensitive layer is less than 5 μm, it may be difficult to form the photosensitive layer uniformly or the mechanical strength may be reduced. On the other hand, when the thickness of the photosensitive layer exceeds 100 μm, the photosensitive layer may be easily peeled off from the substrate.
Accordingly, the thickness of the photosensitive layer is more preferably set to a value within the range of 10 to 50 μm, and further preferably set to a value within the range of 15 to 45 μm.

(6) Manufacturing method of single-layer type electrophotographic photosensitive member The manufacturing method of the single-layer type electrophotographic photosensitive member is not particularly limited, but can be carried out by the following procedure.
First, a coating solution is prepared by adding a charge generating agent, a charge transporting agent, a binder resin, an additive and the like to a solvent. The coating solution thus obtained is applied onto a conductive substrate (aluminum tube) using a coating method such as a dip coating method, a spray coating method, a bead coating method, a blade coating method, or a roller coating method. Apply.
Then, for example, it is dried with hot air at 100 ° C. for 30 minutes to obtain a single layer type electrophotographic photosensitive member having a photosensitive layer having a predetermined thickness.
In addition, various organic solvents can be used as a solvent for preparing the dispersion, for example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane. Aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,3- Ethers such as dioxolane and 1,4-dioxane; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformaldehyde, di Examples include methylformamide and dimethyl sulfoxide. These solvents are used alone or in admixture of two or more. At this time, in order to improve the dispersibility of the charge generating agent and the smoothness of the surface of the photoreceptor layer, a surfactant, a leveling agent, and the like may be further contained. Further, an antioxidant may be added to further improve the gas property.

It is also preferable to form an intermediate layer on the substrate before forming this photosensitive layer.
In forming this intermediate layer, a binder resin and, if necessary, an additive (organic fine powder or inorganic fine powder) together with an appropriate dispersion medium, a known method such as a roll mill, ball mill, attritor, paint shaker, ultrasonic wave A coating solution is prepared by dispersing and mixing using a disperser or the like, and this is applied by a known means such as a blade method, a dipping method, or a spray method, and subjected to heat treatment to form an intermediate layer.
In addition, the additive is in a range where precipitation during production does not become a problem, and various additives (organic fine powder or inorganic fine powder are used for the purpose of preventing the occurrence of interference fringes by causing light scattering. ) Can be added in small amounts.
Next, the obtained coating solution is applied to a support substrate (aluminum base tube) according to a known production method, such as dip coating, spray coating, bead coating, blade coating, roller coating, etc. It can apply | coat using the apply | coating method.
Then, it is preferable to perform the process of drying the coating liquid on a base | substrate at the temperature of 20-200 degreeC for 5 minutes-2 hours.

  In addition, various organic solvents can be used as a solvent for producing such a coating solution, for example, alcohols such as methanol, ethanol, isopropanol, and butanol; aliphatic carbonization such as n-hexane, octane, and cyclohexane. Hydrogen: aromatic hydrocarbons such as benzene, toluene, xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene; ketones such as acetone, methyl ethyl ketone, cyclohexanone; ethyl acetate, methyl acetate, etc. Esters: dimethylformaldehyde, dimethylformamide, dimethylsulfoxide and the like. These solvents are used alone or in admixture of two or more.

[Second Embodiment]
The second embodiment is an image forming apparatus having a process speed of more than 120 mm / sec having a charging unit, an exposure unit, a developing unit, and a transfer unit around the electrophotographic photosensitive member. A photosensitive layer having a charge potential on the surface within a range of 600 to 1000 V and an electrophotographic photosensitive member comprising a charge generator, a hole transport agent, an electron transport agent and a binder resin in the same layer on a substrate. A single-layer electrophotographic photosensitive member having a binder resin having a viscosity average molecular weight of 29000 or less, and the binder resin having only one type selected from the general formulas (1) to (2). by weight of polycarbonate resin, the molecular weight of the electron transport agent to a value within the range of 300 to 502.6, a molecular weight of the hole transport agent to a value within the range of 400 to 680, the charge generating agent, the following characteristics ( ) And an image forming apparatus which is a titanyl phthalocyanine crystal having a (B).
(A) The CuKα characteristic X-ray diffraction spectrum has main peaks at Bragg angles 2θ ± 0.3 ° = 9.5 and 27.2 °.
(B) In the differential scanning calorimetry spectrum, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
The image forming apparatus as the second embodiment will be specifically described below.

1. Basic Configuration As an image forming apparatus according to the second embodiment, a copying machine 30 as shown in FIG. 5 can be preferably used. The copying machine 30 includes an image forming unit 31, a paper discharge unit 32, an image reading unit 33, and a document feeding unit 34. The image forming unit 31 further includes an image forming unit 31a and a paper feeding unit 31b. In the illustrated example, the document feeding unit 34 includes a document placing tray 34a, a document feeding mechanism 34b, and a document discharge tray 34c, and the document placed on the document placing tray 34a. Is fed to the image reading position P by the document feeding mechanism 34b and then discharged to the document discharge tray 34c.

Then, when the original is sent to the original reading position P, the image reading unit 33 reads the image on the original using the light from the light source 33a. That is, an image signal corresponding to the image on the document is formed using an optical element 33b such as a CCD.
On the other hand, recording sheets (hereinafter simply referred to as “sheets”) S stacked on the sheet feeding unit 31b are sent one by one to the image forming unit 31a. The image forming unit 31a is provided with an electrophotographic photosensitive member 41 as an image carrier. Further, around the electrophotographic photosensitive member 41, a charging unit 42, an exposing unit 43, a developing unit 44, and The transfer roller 45 and the cleaning unit 46 are arranged along the rotation direction of the electrophotographic photosensitive member 41.

Among these components, the electrophotographic photoreceptor 41 is rotationally driven in the direction indicated by the solid line arrow in the figure, and the surface thereof is uniformly charged by the charging means 42. Thereafter, an exposure process is performed on the electrophotographic photosensitive member 41 by the exposure unit 43 based on the above-described image signal, and an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member 41.
Based on the electrostatic latent image, the developing means 44 attaches toner and develops it to form a toner image on the surface of the electrophotographic photoreceptor 41. The toner image is transferred as a transfer image onto the sheet S conveyed to the nip portion between the electrophotographic photosensitive member 41 and the transfer roller 45. Next, the sheet S to which the transferred image is transferred is conveyed to the fixing unit 47 and a fixing process is performed.

Further, the sheet S after fixing is sent to the paper discharge unit 32. However, when performing post-processing (for example, stapling processing), the paper S is sent to the intermediate tray 32a and then post-processed. Is done. Thereafter, the sheet S is discharged to a discharge tray portion (not shown) provided on the side surface of the image forming apparatus. On the other hand, when no post-processing is performed, the sheet S is discharged to a discharge tray 32b provided below the intermediate tray 32a. The intermediate tray 32a and the paper discharge tray 32b are configured as a so-called in-body paper discharge unit.
Next, after the transfer is performed as described above, residual toner (and paper dust) remaining on the electrophotographic photosensitive member 41 is removed by the cleaning unit 46. That is, while the electrophotographic photosensitive member 41 is cleaned, the residual toner is collected in a waste toner container (not shown).
On the other hand, in the case of the present invention, as will be described later, it is possible to omit the cleaning unit and perform so-called simultaneous development cleaning in which the developing unit performs cleaning simultaneously with development.
Hereinafter, the electrophotographic photosensitive member, the charging unit, and the developing unit, which are main components in the present invention, will be described more specifically.

2. Electrophotographic Photoreceptor In the present invention, a predetermined single layer type electrophotographic photoreceptor is used as the electrophotographic photoreceptor.
That is, an electrophotographic photosensitive member mounted on an image forming apparatus having a charging potential value in the range of 600 to 1000 V and having a process speed exceeding 120 mm / sec, wherein at least a charge is formed on the conductive substrate. A photoconductor layer including a generator, a hole transport agent, an electron transport agent, and a binder resin is provided. The viscosity average molecular weight of the binder resin is set to a value of 30000 or less, and the charge generator has the following characteristics ( A single-layer electrophotographic photosensitive member characterized by being an oxotitanyl phthalocyanine crystal having A) and (B) is used.
Note that the description of the predetermined single-layer type electrophotographic photosensitive member has been described in the first embodiment, and thus will be omitted.

3. Charging means The charging means in the present invention is characterized in that the charging potential on the surface of the photosensitive layer of a single layer type electrophotographic photosensitive member as a charging target is charged to a value in the range of 600 to 1000V.
The reason for this is that the difference between the post-exposure potential of the photosensitive layer and the charged potential can be increased by setting the charging potential to a relatively high value in this way. This is because not only can it be formed, but it can also be used for further high-speed image formation.
On the other hand, when the charging potential is set to a relatively high value, the oxidizing gas generated from the charging means increases, so that oxidation deterioration of the photosensitive layer made of an organic material becomes a problem.
Specifically, it is difficult to maintain charging stability when performing durable printing.
In this regard, in the present invention, since a predetermined single-layer type electrophotographic photoreceptor excellent in gas resistance is used, the charging potential can be set to a relatively high value without concern for such problems. It becomes possible.
Here, the numerical range of the charging potential on the surface of the photosensitive layer will be described. When this value is less than 600 V, it becomes difficult to increase the difference between the post-exposure potential and the charging potential. It may be difficult to support image formation. On the other hand, when the charged potential on the surface of the photosensitive layer exceeds 1000 V, the amount of oxidizing gas generated from the charging means increases excessively, even though a predetermined single layer type electrophotographic photosensitive member is used. Therefore, it may be difficult to sufficiently maintain the charging stability.
Therefore, the charging potential on the surface of the photosensitive layer is more preferably set to a value within the range of 625 to 975V, and further preferably set to a value within the range of 650 to 950V.

Further, as such charging means, it is preferable to use non-contact type charging means such as scorotron, corotron and the like.
The reason for this is that when such a non-contact type charging means is used, the amount of oxidizing gas generated in the charging step is further increased. This is because, since the photosensitive member is mounted, deterioration of the photosensitive layer surface is effectively suppressed.
As a result, even when image formation is repeatedly performed, a high-quality image can be stably formed.
The applied voltage applied to the non-contact type charging means is preferably a value in the range of 1 to 10 kV, and more preferably a value in the range of 2 to 9 kV.
The other charging means is not particularly limited as long as a predetermined charging potential can be realized, and a contact-type charging means such as a charging roller or a charging brush may be used.

4). Developing means Further, the developing means in the present invention is preferably a developing means of a simultaneous development cleaning system.
The reason for this is that the residual toner and foreign matter on the surface of the photosensitive layer are generally difficult to clean with the developing means of the simultaneous development cleaning method, but with the present invention, a predetermined unit having excellent gas resistance in the photosensitive layer. Since the layer type electrophotographic photosensitive member is mounted, even if residual toner or foreign matter remains on the surface of the photosensitive layer, the surface of the photosensitive layer is not easily deteriorated. Therefore, even when repeated image formation is performed. This is because a high-quality image can be stably formed.
Further, according to the present invention, since the value of the charging potential is set to a relatively high value, even when residual toner or foreign matter remains on the surface of the photosensitive layer, the photosensitive layer is relatively stably provided. This is because the surface can be charged to a predetermined level.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, it cannot be overemphasized and this invention is not limited to these description content without a particular reason.

[ Reference Example 1]
1. Manufacture of electrophotographic photoreceptor (1) Formation of photosensitive layer Crystal of 3 weight of oxotitanyl phthalocyanine (CGM-1) represented by formula (12) as a charge generating agent manufactured by a manufacturing method described later in a container Parts, 50 parts by weight of a hole transporting agent (HTM-1) represented by the following formula (13), 30 parts by weight of an electron transporting agent (ETM-1) represented by the following formula (14), and a binder resin 100 parts by weight of a polycarbonate resin (Resin-9) represented by the formula (11) having a viscosity average molecular weight of 10,000 and 800 parts by weight of tetrahydrofuran as a solvent were accommodated to obtain a mixture thereof. Next, this mixture was mixed and dispersed for 50 hours using a ball mill to obtain a photosensitive layer coating solution.
Next, the obtained coating solution for the photosensitive layer was applied on an aluminum substrate having a diameter of 30 mm and a length of 254 mm by a dip coating method, and then dried with hot air at 100 ° C. for 40 minutes to obtain a film thickness of 30 μm. A single layer type electrophotographic photosensitive member was obtained.
In addition, it was confirmed that the crystals of oxotitanyl phthalocyanine (CGM-1) satisfy all the characteristics (A) to (C).

(2) Manufacture of oxo titanyl phthalocyanine crystal In addition, the crystal | crystallization of the oxo titanyl phthalocyanine (CGM-1) represented by Formula (12) as a charge generator was manufactured as follows.

(2) -1 Synthesis of crude oxotitanyl phthalocyanine crystal First, in an argon-substituted flask, 22 g (0.17 mol) of o-phthalonitrile, 25 g (0.073 mol) of titanium tetrabutoxide, 300 g of quinoline, urea 2 .28 g (0.038 mol) was added, and the temperature was raised to 150 ° C. while stirring.
Next, the temperature of the system was raised to 215 ° C. while distilling off the vapor generated from the reaction system, and the mixture was further stirred for 2 hours while maintaining this temperature.
Then, after the reaction is completed, when the reaction mixture is cooled to 150 ° C., the reaction mixture is taken out of the flask, filtered through a glass filter, and the resulting solid is washed successively with N, N-dimethylformamide and methanol and then vacuum-dried. Then, 24 g of a blue-violet solid as a crude oxotitanyl phthalocyanine crystal was synthesized.

(2) -2 Pre-acid treatment step 10 g of the blue-violet solid obtained in the production of the oxotitanyl phthalocyanine compound described above was added to 100 ml of N, N-dimethylformamide, heated to 130 ° C. with stirring, and heated to 2 ° C. Stir processing was performed for a time.
Next, the heating was stopped when 2 hours passed, and further the stirring was stopped when the temperature was cooled to 23 ± 1 ° C. In this state, the liquid was allowed to stand for 12 hours for stabilization treatment. The stabilized supernatant was filtered off with a glass filter, and the resulting solid was washed with methanol and then vacuum dried to obtain 9.83 g of crude crystals of an oxotitanyl phthalocyanine compound.

(2) -3 Acid treatment step 5 g of crude crystals of oxotitanyl phthalocyanine obtained in the above-mentioned acid treatment pre-treatment were 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 ° 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 crystals of unsubstituted oxotitanylphthalocyanine represented by the formula (12) (blue powder). 1 g was obtained.

(2) -4 Evaluation of oxotitanyl phthalocyanine crystal (X-ray diffraction measurement)
0.3 g of the obtained oxotitanyl phthalocyanine crystal was dispersed in 5 g of tetrahydrofuran, stored in a closed system for 24 hours under conditions of a temperature of 23 ± 1 ° C. and a relative humidity of 50-60%, and then the tetrahydrofuran was removed. The measurement was performed by filling a sample holder of an X-ray diffractometer (RINT1100 manufactured by Rigaku Corporation). The obtained spectrum chart is shown in FIG.
In addition, this spectrum chart has a characteristic that it has a maximum peak at a Bragg angle 2θ ± 0.2 ° = 27.2 ° and has no peak at 26.2 °. It was confirmed that the titanyl phthalocyanine crystal had a stable predetermined crystal type. This is because the peak at the Bragg angle 2θ ± 0.2 ° = 27.2 ° is a peak peculiar to the above-mentioned predetermined crystal type, and the peak at 26.2 ° is a peculiar peak to the β-type crystal. Because there is.
Note that a spectrum chart similar to that shown in FIG. 6 was also measured before the dispersion in tetrahydrofuran.
The measurement conditions for the X-ray diffraction 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

(Differential scanning calorimeter measurement)
Moreover, the differential scanning calorimetry of the obtained oxo titanyl phthalocyanine crystal | crystallization was performed using the differential scanning calorimeter (Rigaku Denki Co., Ltd. product TAS-200 type, DSC8230D). The obtained differential scanning analysis chart is shown in FIG. Further, in this chart, one peak was confirmed at 296 ° C. in addition to the peak accompanying vaporization of adsorbed water.
The measurement conditions were as follows.
Sample pan: Aluminum heating rate: 20 ° C / min

2. Evaluation (1) Image characteristic evaluation The obtained electrophotographic photosensitive member was subjected to a Kyocera Mita printer FS-1010 with a drum rotation speed of 140 mm / sec, cleaning means: roller cleaning system, charging means: scorotron (charging potential 850 V) , Transfer means: roller system), and continuously printed 5000 sheets of A4 paper (Fuji Xerox high-quality PPC paper) under environmental conditions of 35 ° C. and 85% Rh.
Next, after being left for 6 hours, an A4 paper gray document was printed, and the A4 paper was visually observed for white spots, and image characteristics were evaluated in a high-temperature and high-humidity environment according to the following criteria. .
A: No white spots are observed at all.
○: White spots are slightly observed.
Δ: Streaky white spots are observed, which are less than the charger width.
X: Streaky white spots are observed, which are larger than the charger width.

(2) Evaluation of ozone resistance Using a drum sensitivity tester (manufactured by GENTEC), the photoconductor is charged so as to satisfy the current condition of 8 μA (circumferential speed 31 rpm), and the average surface potential of four rounds is defined as the initial surface potential. did.
Next, the photoconductor was exposed at room temperature for 6 hours in an atmosphere having an ozone concentration of 10 ppm in a dark place. The surface potential immediately after the exposure was measured in the same manner.
Next, ΔV0 was calculated from the following equation, and ozone resistance was evaluated according to the following criteria. It can be said that the smaller the ΔV0, the better the ozone resistance of the photoreceptor.
(Initial surface potential)-(Surface potential immediately after exposure) = ΔV0
A: Less than 30V ○: Less than 30-60V Δ: Less than 60-90V x: 90V or more

(3) Evaluation of sensitivity The light potential of the obtained electrophotographic photosensitive member was measured. That is, using a drum sensitivity tester (produced by GENTEC), the surface potential was charged to 700 V, and then monochromatic light having a wavelength of 780 nm extracted from white light using a band pulse filter (half-width: 20 nm, The surface of the electrophotographic photosensitive member was exposed (light intensity: 0.3 μJ / cm ² ) (irradiation time: 50 msec). Next, the potential after 350 msec after exposure was measured, and the sensitivity was evaluated based on the following criteria. The obtained results are shown in Table 1.
◎: Less than 120V ○: 120 to less than 150V Δ: 150 to less than 180V ×: 180V or more

[ Reference Examples 2-3]
In Reference Examples 2-3, a single-layer electrophotographic photosensitive member was prepared in the same manner as in Reference Example 1, except that the binder resin in Reference Example 1 had a viscosity average molecular weight of 10,000 and 30,000, respectively. It was manufactured and evaluated. The obtained results are shown in Table 1.

[Examples 4 to 6]
In Examples 4-6, except that the kind and viscosity average molecular weight of the binder resin in Example 1 were changed as shown in Table 1, with each producing a single-layer type electrophotographic photoreceptor in the same manner as in Reference Example 1 ,evaluated. The obtained results are shown in Table 1.
The binder resin used in Example 4 is a polycarbonate copolymer resin (Resin-4) represented by the formula (6).
The binder resin used in Example 5 is a polycarbonate copolymer resin (Resin-6) represented by the formula (8).
Further, the binder resin used in Example 6 is a polycarbonate copolymer resin (Resin-3) represented by the formula (5).

[ Reference Examples 7 to 24]
In Reference Examples 7 to 24, the type of hole transport agent in Reference Example 1 was changed to hole transport agents (HTM-2 to 19) represented by the following formulas (15) to (32), respectively, and a binder resin was used. A single-layer electrophotographic photosensitive member was produced and evaluated in the same manner as in Reference Example 1 except that the viscosity average molecular weight was changed to 20000. The obtained results are shown in Table 1.

[ Reference Examples 25 to 28]
In Reference Examples 25 to 28, the type of the electron transfer agent in Reference Example 1 is changed to the electron transfer agent (ETM-2 to 5) represented by the following formulas (33) to (36), respectively, and the viscosity of the binder resin is changed. A single-layer electrophotographic photosensitive member was produced and evaluated in the same manner except that the electron transport agent was changed as shown in Table 1 except that the average molecular weight was changed to 20000. The obtained results are shown in Table 1.

[Comparative Examples 1-3]
In Comparative Examples 1 to 3, the charge generating agent of Reference Example 1 was changed to x-type metal-free phthalocyanine (CGM-2) represented by the following formula (37), and the type and viscosity average molecular weight of the binder resin are shown in Table 1. A single-layer electrophotographic photosensitive member was produced and evaluated in the same manner except that it was changed as shown. The obtained results are shown in Table 1.

[Comparative Examples 4 to 7]
In Comparative Examples 4 to 7, single-layer electrophotographic photosensitive members were similarly prepared except that the type of the binder resin in Reference Example 1 was changed as shown in Table 1 and the viscosity average molecular weight was changed to 38,000 to 60,000. It was manufactured and evaluated. The obtained results are shown in Table 1.

[Comparative Examples 8-9]
In Comparative Examples 8 to 9, single-layer electrons were similarly obtained except that the charge generator in Reference Example 1 was changed to Y-type titanyl phthalocyanine crystals and the viscosity average molecular weight of the binder resin was changed to 40,000 to 60,000. Photoconductors were manufactured and evaluated. The obtained results are shown in Table 1.

Even if the process speed is set to a higher value than the predetermined value or the charging potential is set to a higher value than the predetermined value, the viscosity average of the binder resin in the single layer type electrophotographic photosensitive member By setting the molecular weight to a predetermined value and using a charge generating agent having predetermined characteristics, the gas resistance in the photosensitive layer can be effectively improved without using a considerable amount of antioxidant. It was.
Therefore, the single-layer electrophotographic photosensitive member and the image forming apparatus according to the present invention are expected to significantly contribute to the long life and the stabilization of image quality in various image forming apparatuses such as copying machines and printers.

10: single layer type photoreceptor, 10 ': single layer type photoreceptor having an intermediate layer, 12: conductive substrate, 14: photoreceptor layer, 16: intermediate layer, 30: copying machine, 31: image forming unit, 31a : Image forming unit, 31b: Paper feeding unit, 32: Paper discharge unit, 33: Image reading unit, 33a: Light source, 33b: Optical element, 34: Document feeding unit, 34a: Document loading tray, 34b: Document feeding Feed mechanism 34c: Document discharge tray 41: Photoconductor drum 42: Charger 43: Exposure source 44: Developer 45: Transfer roller 46: Cleaning device

Claims (5)

An electrophotographic photosensitive member mounted on an image forming apparatus having a charging potential value in a range of 600 to 1000 V and a process speed exceeding 120 mm / sec,
Provided with a photoreceptor layer containing at least a charge generator, a hole transport agent, an electron transport agent, and a binder resin on a conductive substrate;
While setting the viscosity average molecular weight of the binder resin to a value of 29000 or less ,
The binder resin includes only one type of polycarbonate resin selected from the following formulas (1) to (2):
The molecular weight of the electron transfer agent is a value within the range of 300 to 502.6,
The molecular weight of the hole transport agent is a value within the range of 400 to 680,
A single-layer electrophotographic photoreceptor, wherein the charge generating agent is an oxotitanyl phthalocyanine crystal having the following characteristics (A) and (B).
(A) The CuKα characteristic X-ray diffraction spectrum has main peaks at Bragg angles 2θ ± 0.3 ° = 9.5 and 27.2 °.
(B) In the differential scanning calorimetry spectrum, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
(In the general formula (1), the plurality of substituents Ra and Rb are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts p and q are each independently an integer of 0 to 4, and the substituents Rc and Rd are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms. W is a single bond, —O—, —CO—, —CH ₂ —, and the subscripts k and l are molar ratios satisfying the relational expression of 0 <l / (k + 1) <0.6. .)
(In the general formula (2), the plurality of substituents Re and Rf are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts r and s are each independently an integer of 0 to 4, and the subscripts m and n are molar ratios satisfying a relational expression of 0 <n / (n + m) <0.6. And W is —O—, —CO—, or —CH ₂ —.) The single-layer electrophotographic photosensitive member according to claim 1, wherein the oxotitanyl phthalocyanine crystal further has the following characteristic (C).
(C) In the CuKα characteristic X-ray spectrum, the ratio A / B between the peak intensity A at the Bragg angle 2θ ± 0.3 ° = 7.2 ° and the peak intensity B at 9.5 ° (hereinafter referred to as α degree) Is a value within the range of 0.05 to 0.25. An image forming apparatus having a charging speed, an exposure means, a development means and a transfer means around an electrophotographic photosensitive member, the process speed of which exceeds 120 mm / sec,
The charging potential on the surface of the electrophotographic photosensitive member by the charging means is a value in the range of 600 to 1000 V,
The electrophotographic photoreceptor is a single layer type electrophotographic photoreceptor having a photosensitive layer containing a charge generator, a hole transport agent, an electron transport agent and a binder resin in the same layer on a substrate,
While setting the viscosity average molecular weight of the binder resin to a value of 29000 or less ,
The binder resin includes only one type of polycarbonate resin selected from the following formulas (1) to (2):
The molecular weight of the electron transfer agent is a value within the range of 300 to 502.6,
The molecular weight of the hole transport agent is a value within the range of 400 to 680,
An image forming apparatus, wherein the charge generating agent is an oxo titanyl phthalocyanine crystal having the following characteristics (A) and (B):
(A) CuKα characteristic X-ray diffraction spectrum has main peaks at Bragg angles 2θ ± 0.3 ° = 9.5 and 27.2 °.
(B) In the differential scanning calorimetry spectrum, it has one peak in the range of 270 to 400 ° C. in addition to the peak accompanying vaporization of adsorbed water.
(In the general formula (1), the plurality of substituents Ra and Rb are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts p and q are each independently an integer of 0 to 4, and the substituents Rc and Rd are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms. W is a single bond, —O—, —CO—, —CH ₂ —, and the subscripts k and l are molar ratios satisfying the relational expression of 0 <l / (k + 1) <0.6. .)
(In the general formula (2), the plurality of substituents Re and Rf are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or non-substituted group having 6 to 30 carbon atoms. A substituted aryl group, the subscripts r and s are each independently an integer of 0 to 4, and the subscripts m and n are molar ratios satisfying a relational expression of 0 <n / (n + m) <0.6. And W is —O—, —CO—, or —CH ₂ —.) The image forming apparatus according to claim 3 , wherein the charging unit is a non-contact type charging unit. The image forming apparatus according to claim 3 , wherein the image forming apparatus is an image forming apparatus of a simultaneous development cleaning type.