JP2017053982A - Single-layer electrophotographic photoreceptor, manufacturing method of single-layer electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single-layer electrophotographic photoreceptor that has excellent transferability.SOLUTION: A single-layer electrophotographic photoreceptor comprises a conductive substrate and a photosensitive layer. The photosensitive layer contains a polyester resin as a binder resin. The photosensitive layer has a thickness of 25.0 μm or less. The conductive substrate contains aluminum or aluminum alloy. The conductive substrate has, on its surface, an aluminum oxide film or an aluminum alloy oxide film. The abundance ratio R of oxygen atoms in the surface of the conductive substrate calculated from the formula (1) R=100×A/(A+A) is larger than 0.0% and 15.0% or less. In the formula (1), Ais the concentration of oxygen atoms obtained by measuring the surface of the conductive substrate by using energy dispersive X-ray spectroscopy. Ais the concentration of aluminum atoms obtained by measuring the surface of the conductive substrate by using energy dispersive X-ray spectroscopy.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a single layer type electrophotographic photosensitive member, a method for producing a single layer type electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

  The electrophotographic photosensitive member is used in an electrophotographic image forming apparatus. The electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer contains, for example, a charge generator, a charge transport agent (for example, a hole transport agent and an electron transport agent), and a resin (binder resin) that binds them. In an example of the electrophotographic photoreceptor, the charge generation agent and the charge transport agent are contained in the same layer (photosensitive layer), and both functions of charge generation and charge transport are provided in the same layer. Such an electrophotographic photoreceptor is referred to as a single layer type electrophotographic photoreceptor.

  The positively charged single layer type electrophotographic photosensitive member described in Patent Document 1 includes at least a conductive substrate and a photosensitive layer. The photosensitive layer is a layer containing a charge generator, a hole transport agent, an electron transport agent, and a binder resin in the same layer. As a specific example of the binder resin, bisphenol Z-type polycarbonate resin is used.

JP 2012-234001 A

  However, the positively charged single layer type electrophotographic photosensitive member described in Patent Document 1 has not been sufficiently transferable.

  The present invention has been made in view of the above problems, and an object thereof is to provide a single-layer electrophotographic photosensitive member, a process cartridge, and an image forming apparatus that are excellent in transferability. Another object of the present invention is to provide a method for producing a single layer type electrophotographic photoreceptor excellent in transferability.

The single layer type electrophotographic photoreceptor of the present invention comprises a conductive substrate and a photosensitive layer. The photosensitive layer contains at least a polyester resin as a binder resin. The photosensitive layer has a thickness of 25.0 μm or less. The conductive substrate contains aluminum or an aluminum alloy. The surface of the conductive substrate has the aluminum oxide film or the aluminum alloy oxide film. The abundance ratio R of oxygen atoms on the surface of the conductive substrate calculated from the following mathematical formula (1) is greater than 0.0% and not more than 15.0%.
R = 100 × A _O / (A _O + A _Al ) (1)
(In Formula (1), A 2 _O is the oxygen atom concentration obtained by measuring the surface of the conductive substrate using energy dispersive X-ray spectroscopy. A _Al is energy dispersive X-ray. (This is the aluminum atom concentration obtained by measuring the surface of the conductive substrate using spectroscopy.)

  The method for producing a single layer type electrophotographic photosensitive member of the present invention is the above-described method for producing a single layer type electrophotographic photosensitive member. The manufacturing method of the single layer type electrophotographic photosensitive member of the present invention includes a preparation step and an oxide film formation step. In the preparation step, a conductive substrate containing the aluminum or the aluminum alloy is prepared. In the oxide film forming step, the aluminum oxide film or the aluminum alloy is formed on the surface of the conductive substrate by bringing the conductive substrate containing the aluminum or the aluminum alloy into contact with hot water. An oxide film is formed. The temperature of the hot water is 50 ° C. or higher and 70 ° C. or lower. The time for contacting the conductive substrate and the hot water is not less than 1 second and not more than 300 seconds.

  The process cartridge of the present invention includes the above-described single layer type electrophotographic photosensitive member.

  An image forming apparatus according to the present invention includes the above-described single-layer electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit. The charging unit charges the surface of the single-layer electrophotographic photosensitive member. The exposure unit exposes the charged surface of the single-layer electrophotographic photosensitive member to form an electrostatic latent image on the surface of the single-layer electrophotographic photosensitive member. The developing unit develops the electrostatic latent image as a toner image. The transfer unit transfers the toner image from the single-layer electrophotographic photosensitive member to a transfer target.

  According to the single layer type electrophotographic photosensitive member, the process cartridge, and the image forming apparatus of the present invention, transferability can be improved. Moreover, according to the single layer type electrophotographic photosensitive member of the present invention, a single layer type electrophotographic photosensitive member having excellent transferability can be produced.

It is a graph which shows the relationship between a transfer current and image density. (A), (b), (c) is a schematic sectional drawing which respectively shows the structure of the single layer type electrophotographic photoreceptor which concerns on 1st embodiment. It is the schematic which shows the structure of the one aspect | mode of the image forming apparatus which concerns on 3rd embodiment. It is the schematic which shows the structure of another aspect of the image forming apparatus which concerns on 3rd embodiment.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

  Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. In addition, when “polymer” is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

<First Embodiment: Single Layer Type Electrophotographic Photoreceptor>
The first embodiment relates to a single-layer electrophotographic photosensitive member (hereinafter sometimes referred to as “photosensitive member”) 1. The photoreceptor 1 is excellent in transferability. First, the transferability of the photoreceptor 1 will be described with reference to FIG.

  FIG. 1 is a graph showing the relationship between transfer current and image density. In FIG. 1, the horizontal axis represents the transfer current (unit: -μA). The value shown on the right side of the horizontal axis in FIG. 1 indicates that the value shown on the right side is smaller, that is, the absolute value of the transfer current is larger. When the toner image formed on the surface of the photosensitive member 1 is transferred from the photosensitive member 1 to the transfer target 38 (for example, the paper P in FIG. 3), the transfer current 26 (for example, in FIG. This is a current applied to the photosensitive member 1 by the transfer roller 41). In FIG. 1, the vertical axis represents the image density. The image density is an image density of an image formed on the paper P when an image is formed on the paper P (see FIG. 3) using the image forming apparatus 6 including the photoreceptor 1 and toner. For convenience of explanation, FIG. 1 illustrates an example in which the charging polarity of the photosensitive member 1 is positive. However, the charging polarity of the photosensitive member 1 is not limited to positive polarity.

Assume that a desired image density in an image formed on the paper P is D ₁ or more and D ₂ or less. As the absolute value of the transfer current applied by the transfer unit 26 to the photoreceptor 1 increases from 0, the image density of the image formed on the paper P increases. When the transfer current becomes C ₁ (−μA), an image having a desired lower limit value D ₁ of image density is formed. Subsequently, as the absolute value of the transfer current becomes larger than C ₁ , the image density of the image formed on the paper P gradually increases. When the transfer current becomes C ₂ (−μA), an image having a desired image density upper limit value D ₂ is formed. However, when the absolute value of the transfer current exceeds C ₂ , the image density of the formed image is rapidly reduced. The transfer current C ₂ (−μA) at this time is defined as a transfer failure occurrence current value. A range of transfer current in which an image having an image density of D _{1 to} D ₂ is formed, that is, a range of C ₂ (−μA) to C ₁ (−μA) is set to a normal image density range (C _1-2 ).

Here, it is desired to enlarge the normal range of image density. Specifically, it is desired to increase the absolute value (C ₂ ) of the transfer failure occurrence current value. This is because when the absolute value (C ₂ ) of the transfer failure occurrence current value increases, external factors (for example, temperature, humidity, or the type of the transfer target 38) at the time of image formation fluctuate, so that the transfer unit 26 performs photosensitivity. This is because even when the value of the transfer current applied to the body 1 fluctuates, an image having a desired image density can be stably formed. That is, the photoconductor 1 having a large absolute value (C ₂ ) of the transfer failure occurrence current value is excellent in the transferability of the photoconductor 1.

Here, the photoreceptor 1 of the present embodiment includes a conductive substrate 2 and a photosensitive layer 3 as described later with reference to FIG. The photosensitive layer 3 contains at least a polyester resin as a binder resin. When the photosensitive layer 3 contains a polyester resin, the absolute value (C ₂ ) of the transfer failure occurrence current value tends to increase.

The thickness of the photosensitive layer 3 is 25.0 μm or less. If the thickness of the photosensitive layer 3 is 25.0 μm or less, the absolute value (C ₂ ) of the transfer failure occurrence current value tends to increase.

  Further, the conductive substrate 2 contains aluminum or an aluminum alloy. The surface of the conductive substrate 2 has an aluminum oxide film or an aluminum alloy oxide film. The abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 is more than 0.0% and not more than 15.0%. Such a conductive substrate 2 has a desired amount of charge in the photosensitive layer 3 even when a transfer current having a large absolute value (for example, a strong negative transfer bias) is applied to the photoreceptor 1. There is a tendency to adjust.

Therefore, according to the photosensitive member 1, the absolute value (C ₂ ) of the transfer failure occurrence current value can be increased. As a result, when an external factor (for example, temperature, humidity, or type of the transfer target 38) at the time of image formation changes, the value of the transfer current applied from the transfer unit 26 to the photosensitive member 1 changes. Even in such a case, it is considered that an image having a desired image density can be stably formed using toner. Therefore, it is considered that the photoreceptor 1 is excellent in transferability.

  Next, the photoreceptor 1 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing the structure of the photoreceptor 1. The photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is provided directly or indirectly on the conductive substrate 2. For example, as shown in FIG. 2A, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, for example, as shown in FIG. 2B, an intermediate layer 4 may be provided between the conductive substrate 2 and the photosensitive layer 3. Further, as shown in FIGS. 2A and 2B, the photosensitive layer 3 may be exposed as the outermost layer. Alternatively, a protective layer 5 may be provided on the photosensitive layer 3 as shown in FIG.

<1. Conductive substrate>
The conductive substrate 2 contains aluminum or an aluminum alloy. When the conductive substrate 2 contains aluminum or an aluminum alloy, the movement of charges from the photosensitive layer 3 to the conductive substrate 2 tends to be improved.

  An aluminum alloy is an alloy of aluminum and an element other than aluminum. Examples of elements other than aluminum include manganese (Mn), silicon (Si), magnesium (Mg), copper (Cu), iron (Fe), chromium (Cr), titanium (Ti), and zinc (Zn). It is done. The aluminum alloy may contain one of these elements alone as an element other than aluminum, or may contain two or more kinds in combination. Examples of the aluminum alloy include an Al—Mn alloy (JIS 3000), an Al—Mg alloy (JIS 5000), and an Al—Mg—Si alloy (JIS 6000).

The surface of the conductive substrate 2 has an aluminum oxide film or an aluminum alloy oxide film. The aluminum oxide film or the aluminum alloy oxide film is formed, for example, by oxidizing the surface of the conductive substrate 2. Further, the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 calculated from the mathematical formula (1) is greater than 0.0% and not more than 15.0%. Thereby, the absolute value (C ₂ ) of the transfer failure occurrence current value can be increased. This is presumably because the work function of the conductive substrate 2 is adjusted to a desired value by controlling the abundance ratio R of the oxygen atoms of the conductive substrate 2. As a result, the transferability of the photoreceptor 1 can be improved. In order to further improve the transferability of the photoreceptor 1, the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 is preferably larger than 4.0% and not larger than 12.0%.

An example of a method for measuring the oxygen atom abundance ratio R on the surface of the conductive substrate 2 will be described. First, the surface of the conductive substrate 2 is measured by energy dispersive X-ray spectroscopy (EDX) using an energy dispersive X-ray spectrometer (“JSM-6380LV” manufactured by JEOL Ltd.). The measurement condition is set to an acceleration voltage of 5 keV. Thus, the oxygen atom concentration (A _O , unit: atomic%) and the aluminum atom concentration (A _Al , unit: atomic%) on the surface of the conductive substrate 2 are measured. Based on the measured oxygen atom concentration and aluminum atom concentration, an abundance ratio R of oxygen atoms is calculated according to Equation (1).
R = 100 × A _O / (A _O + A _Al ) (1)

In Equation (1), A 2 _O is an oxygen atom concentration (unit: atomic%) obtained by measuring the surface of the conductive substrate 2 using energy dispersive X-ray spectroscopy. A _Al is an aluminum atom concentration (unit: atomic%) obtained by measuring the surface of the conductive substrate 2 using energy dispersive X-ray spectroscopy.

  The shape of the conductive substrate 2 is appropriately selected according to the structure of the image forming apparatus 6 described later in the third embodiment. Examples of the shape of the conductive substrate 2 include a sheet shape and a drum shape. Further, the thickness of the conductive substrate 2 is appropriately selected according to the shape of the conductive substrate 2.

<2. Photosensitive layer>
The thickness of the photosensitive layer 3 is 25.0 μm or less. If the thickness of the photosensitive layer 3 is 25.0 μm or less, the absolute value (C ₂ ) of the transfer failure occurrence current value tends to increase. The reason is presumed as follows. The charge (Q) injected into the photosensitive layer 3 tends to be proportional to the voltage (V) and inversely proportional to the thickness (d) of the photosensitive layer 3. Therefore, when the voltage (V) applied to the photosensitive member 1 by the charging unit 27 (see FIG. 3) has the same value, the smaller the thickness (d) of the photosensitive layer 3 is injected into the photosensitive layer 3 during charging. The charge (Q) is considered to increase. Therefore, if the thickness of the photosensitive layer 3 is 25.0 μm or less, the charge (Q) injected into the photosensitive layer 3 during charging increases, and the current applied to the photosensitive member 1 during transfer (with a polarity opposite to that of charging). Less susceptible to current). In order to further improve the transferability of the photoreceptor 1, the thickness of the photosensitive layer 3 is preferably 20.0 μm or less, and more preferably 15.0 μm or less.

  The thickness of the photosensitive layer 3 is preferably 10.0 μm or more. As already described, the charge (Q) injected into the photosensitive layer 3 tends to be proportional to the voltage (V) and inversely proportional to the thickness (d) of the photosensitive layer 3. When the voltage (V) applied to the photoreceptor 1 by the charging unit 27 (see FIG. 3) has the same value, the charge (Q) injected into the photosensitive layer 3 as the thickness (d) of the photosensitive layer 3 increases. Is expected to decrease. Therefore, if the thickness of the photosensitive layer 3 is 10 μm or more, it is considered that the charge (Q) injected into the photosensitive layer 3 does not increase excessively, and charge leakage from the photosensitive layer 3 is suppressed. As a result, it is considered that the occurrence of black spots in the formed image is suppressed.

  The thickness of the photosensitive layer 3 is preferably from 10.0 μm to 25.0 μm, more preferably from 10.0 μm to 20.0 μm, and particularly preferably from 10.0 μm to 15.0 μm. preferable.

  The thickness of the photosensitive layer 3 is adjusted, for example, by appropriately changing the viscosity of the coating solution used in the coating process described later. The viscosity of the coating solution is measured according to Japanese Industrial Standard (JIS) Z8803, for example, using a torsional vibration viscometer ("FVM-80A" manufactured by Seconic Corporation). The viscosity is measured, for example, in an environment of a temperature of 23 ° C. and a humidity of 60% RH (unit of relative humidity). The thickness of the photosensitive layer 3 is also adjusted by appropriately changing the speed at which the immersed conductive substrate 2 is lifted from the coating solution in the coating step described later. The thickness of the photosensitive layer 3 may be adjusted by appropriately selecting a known method.

  The photosensitive layer 3 contains a binder resin. The photosensitive layer 3 may contain a charge generating agent, a hole transport agent, an electron transport agent, and various additives as necessary.

<2-1. Charge generator>
The charge generator is not particularly limited as long as it is a charge generator for a photoreceptor. Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, and cyanine pigments. , Powders of inorganic photoconductive materials (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, or amorphous silicon), pyrylium salts, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples thereof include pyrazoline pigments and quinacridone pigments.

  Examples of the phthalocyanine pigment include metal-free phthalocyanine represented by the chemical formula (CGM-1) or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine represented by the chemical formula (CGM-2) or phthalocyanine coordinated with a metal other than titanium oxide (for example, V-type hydroxygallium phthalocyanine). The phthalocyanine pigment may be crystalline or non-crystalline. The crystal shape (for example, α-type, β-type, or Y-type) of the phthalocyanine pigment is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

  Examples of the crystal of metal-free phthalocyanine include an X-type crystal of metal-free phthalocyanine (hereinafter sometimes referred to as “X-type metal-free phthalocyanine”). Examples of the titanyl phthalocyanine crystal include α-type crystal, β-type crystal, and Y-type crystal of titanyl phthalocyanine.

  A charge generator having an absorption wavelength in a desired region may be used alone, or two or more charge generators may be used in combination. Further, for example, in the digital optical image forming apparatus 6 (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), the photosensitive member 1 having sensitivity in a wavelength region of 700 nm or more is used. preferable. Therefore, for example, phthalocyanine pigments are preferable, and metal-free phthalocyanine or titanyl phthalocyanine is more preferable. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The photoreceptor 1 applied to the image forming apparatus 6 using a short wavelength laser light source (for example, a laser light source having a wavelength of about 350 nm to about 550 nm) has an sanslon pigment or a perylene pigment as a charge generator. Are preferably used.

  The content of the charge generating agent is preferably 0.1 parts by mass or more and 50 parts by mass or less, and more preferably 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin.

<2-2. Hole transport agent>
The hole transport agent is not particularly limited as long as it can be applied to the photoreceptor 1. As the hole transport agent, for example, a nitrogen-containing cyclic compound or a condensed polycyclic compound can be used. Examples of the nitrogen-containing cyclic compound and the condensed polycyclic compound include triphenylamine derivatives; diamine derivatives (for example, N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N ′). -Tetraphenylphenylenediamine derivative, N, N, N ', N'-tetraphenylnaphthylenediamine derivative, or di (aminophenylethenyl) benzene derivative, or N, N, N', N'-tetraphenylphenanthri Range amine derivatives); oxadiazole compounds (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole); styryl compounds (eg, 9- (4-diethylaminostyryl) ) Anthracene); carbazole compounds (for example, polyvinyl carbazole); organic polysilane compounds; pyrazoline compounds ( For example, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline); hydrazone compound; indole compound; oxazole compound; isoxazole compound; thiazole compound; thiadiazole compound; imidazole compound; Or triazole compounds. These hole transport agents may be used alone or in combination of two or more.

  Specific examples of the hole transporting agent include compounds represented by chemical formulas (HTM-1) to (HTM-9) (hereinafter sometimes referred to as compounds (HTM-1) to (HTM-9)). Can be mentioned.

  The total content of the hole transporting agent is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the binder resin.

<2-3. Electron transport agent>
Examples of electron transfer agents include quinone compounds, diimide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, Examples include dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride, or dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds, azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, nitroanthraquinone compounds, and dinitroanthraquinone compounds. These electron transfer agents may be used alone or in combination of two or more.

  Among these electron transfer agents, compounds represented by the general formula (1), (2), (3), (4), (5) or (6) (hereinafter referred to as “compound (1), (2) , (3), (4), (5) or (6) ”may be preferable). Photoconductor provided with photosensitive layer 3 containing compound (1), (2), (3), (4), (5) or (6) when a negative transfer potential is applied to photoconductor 1 1 is assumed to have the following advantages. When a transfer current having a large absolute value (for example, a strong negative transfer bias) is applied to the photoconductor 1, the potential of the exposed region of the photoconductor 1 that is electrically neutral at the time of exposure is transferred at the time of transfer. May be inclined to the polarity (for example, negative polarity). However, the compounds (1), (2), (3), (4), (5) and (6) are considered to have a suitable reduction potential. Therefore, electrons easily move in the photosensitive layer 3. As a result, the potential of the exposed area of the photoreceptor 1 is easily maintained near neutral even during transfer, and toner (for example, positively charged toner) attached to the exposed area of the photoreceptor 1 is transferred to the photoreceptor 1 during transfer. It becomes difficult to remain. As a result, it is considered that the toner is satisfactorily transferred from the photosensitive member 1 to the transfer target 38.

In the general formulas (1), (2), (3), (4) and (5), R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ each independently represent a hydrogen atom, a cyano group, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or a substituent. An alkoxy group that may have, an alkoxycarbonyl group that may have a substituent, an aralkyl group that may have a substituent, an aryl group that may have a substituent, or a substituent Represents a good heterocyclic group. R ₃₃ is a halogen atom, a hydrogen atom, a cyano group, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. And an optionally substituted alkoxycarbonyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ in the general formulas (1), (2), (3), (4) and (5) Examples of the alkyl group represented by R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ include alkyl groups having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, s-butyl, n-butyl, tert-butyl, n-pentyl, and isopentyl. Group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, or decyl group. Among the alkyl groups having 1 to 10 carbon atoms, alkyl groups having 1 to 6 carbon atoms are preferable, alkyl groups having 1 to 5 carbon atoms are more preferable, methyl group, isopropyl group, and tert-butyl. A group or a 1,1-dimethylpropyl group is particularly preferred. The alkyl group may be linear or branched. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ in the general formulas (1), (2), (3), (4) and (5) Examples of the alkenyl group represented by R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ include alkenyl groups having 2 to 10 carbon atoms. Among the alkenyl groups having 2 to 10 carbon atoms, alkenyl groups having 2 to 6 carbon atoms are preferable, and alkenyl groups having 2 to 4 carbon atoms are more preferable. The alkenyl group may be a linear alkenyl group, a branched alkenyl group, a cyclic alkenyl group, or an alkenyl group combining these. The alkenyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ in the general formulas (1), (2), (3), (4) and (5) Examples of the alkoxy group represented by R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ include an alkoxy group having 1 to 10 carbon atoms. Examples of the alkoxy group having 1 to 10 carbon atoms include methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, and decyloxy group. . Among the alkoxy groups having 1 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms is preferable, and a methoxy group is more preferable. The alkoxy group may be a linear alkoxy group, a branched alkoxy group, a cyclic alkoxy group, or an alkoxy group that combines these. The alkoxy group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, a phenyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ in the general formulas (1), (2), (3), (4) and (5) _{R 41, R 42, R 51} , R 52, and alkoxycarbonyl group R ₅₃ is represented, for example, a carbonyl group attached an alkoxy group having 1 to 10 carbon atoms. The alkoxy group having 1 to 10 carbon atoms contained in the alkoxycarbonyl group is represented by R ₁₁ , R ₁₂ , R ₂₁ in the general formulas (1), (2), (3), (4) and (5), This is the same as the alkoxy group represented by R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ . The alkoxycarbonyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, a phenyl group, an alkoxy group having 1 to 4 carbon atoms, or a cyano group. The number of substituents is not particularly limited, but is preferably 3 or less.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ in the general formulas (1), (2), (3), (4) and (5) Examples of the aralkyl group represented by R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ include aralkyl groups having 7 to 15 carbon atoms. Among the aralkyl groups having 7 to 15 carbon atoms, aralkyl groups having 7 to 13 carbon atoms are preferable, and aralkyl groups having 7 to 12 carbon atoms are more preferable. The aralkyl group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, and a fat having 2 to 4 carbon atoms. An acyl group, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group. The number of substituents is not particularly limited, but is preferably 5 or less, and more preferably 3 or less.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ in the general formulas (1), (2), (3), (4) and (5) As the aryl group represented by R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ and R ₅₃ , for example, a phenyl group, a group formed by condensing two or three benzene rings, or two or Examples include a group formed by connecting three benzene rings by a single bond. The number of benzene rings contained in the aryl group is, for example, 1 or more and 3 or less, and preferably 1 or 2. As the aryl group, a phenyl group is preferable. Examples of the substituent that the aryl group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, and carbon. Examples thereof include an aliphatic acyl group having 2 to 4 atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ in the general formulas (1), (2), (3), (4) and (5) The heterocyclic group represented by R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ is, for example, a 5- or 6-membered group containing one or more heteroatoms selected from the group consisting of N, S, and O Or a heterocyclic group in which such a single ring is condensed with a 5-membered or 6-membered hydrocarbon ring. When the heterocyclic group is a condensed ring, the number of rings contained in the condensed ring is preferably 3 or less. Examples of the substituent that the heterocyclic group may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, Examples thereof include an aliphatic acyl group having 2 to 4 carbon atoms, a benzoyl group, a phenoxy group, an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms, or a phenoxycarbonyl group.

In R ₃₃ in the general formula (3), examples of the halogen atom include a fluoro group, a chloro group, a bromo group, and an iodo group, and a chloro group is preferable.

R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R _{23 in} the general formulas (1), (2), (3), (4) and (5) are easy to improve the transferability of the photoreceptor 1. , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ are preferably the following compounds. R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ are each independently a hydrogen atom, phenyl An alkoxy group having 1 to 6 carbon atoms which may have a group, a phenyl group which may have an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms . R ₃₃ represents a halogen atom.

In the general formula (6), each R ₆₁ is independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, It represents an aralkyl group having 7 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms which may have a substituent. R ₆₂ represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or An aryl group having 6 to 12 carbon atoms which may have a substituent or a heterocyclic group which may have a substituent.

The alkyl group having 1 to 10 carbon atoms represented by R ₆₁ and R _{62 in} the general formula (6) is, for example, in the general formulas (1), (2), (3), (4) and (5) 1 to 10 carbon atoms represented by R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ The same as the following alkyl groups. The alkyl group having 1 to 10 carbon atoms represented by R ₆₁ and R ₆₂ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and tert-butyl. The group is particularly preferred.

Examples of the cycloalkyl group having 3 to 10 carbon atoms represented by R ₆₁ and R _{62 in} the general formula (6) include, for example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, A cyclononyl group or a cyclodecyl group is mentioned.

Examples of the alkoxy group having 1 to 6 carbon atoms represented by R ₆₁ and R _{62 in} the general formula (6) include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, and a hexyloxy group. It is done.

The aralkyl group having 7 to 12 carbon atoms represented by R ₆₁ and R _{62 in} the general formula (6) is an alkyl group having 1 to 6 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms. Of these, a group having 7 to 12 carbon atoms in total. Examples of the aryl group having 6 to 10 carbon atoms contained in the aralkyl group having 7 to 12 carbon atoms include a phenyl group and a naphthyl group. Examples of the alkyl group having 1 to 6 carbon atoms contained in the aralkyl group having 7 to 12 carbon atoms include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, s-butyl group, and n-butyl. Group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, or hexyl group.

Examples of the aryl group having 6 to 12 carbon atoms represented by R ₆₁ and R _{62 in} the general formula (6) include, for example, a phenyl group, a group formed by condensing two benzene rings, or two And a group formed by linking the benzene rings by a single bond. The aryl group having 6 to 12 carbon atoms is preferably a phenyl group. Examples of the substituent that the aryl group having 6 to 12 carbon atoms may have include, for example, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms. , A nitro group, a cyano group, an aliphatic acyl group having 2 to 4 carbon atoms, a benzoyl group, a phenoxy group, and an alkoxycarbonyl group containing an alkoxy group having 1 to 4 carbon atoms.

The heterocyclic group represented by R _{62 in the} general formula (6) is, for example, R ₁₁ , R ₁₂ , R ₂₁ , R in the general formulas (1), (2), (3), (4) and (5). It is the same as the heterocyclic group represented by ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₃₃ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ .

A compound in which R ₆₁ and R ₆₂ in the general formula (6) represent the following groups is preferable because the transferability of the photoreceptor 1 is easily improved. R ₆₁ each independently represents an alkyl group having 1 to 6 carbon atoms. R ₆₂ represents a 12 following an aryl group having 6 or more carbon atoms.

  Specific examples of the compounds (1), (2), (3), (4), (5), and (6) include compounds represented by chemical formulas (ETM-1) to (ETM-6). It is done. Hereinafter, the compounds represented by chemical formulas (ETM-1) to (ETM-6) may be referred to as compounds (ETM-1) to (ETM-6), respectively.

  The content of the electron transport agent is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the binder resin.

<2-4. Binder resin>
The photosensitive layer 3 contains at least a polyester resin as a binder resin. When the photosensitive layer 3 contains the polyester resin, the absolute value (C ₂ ) of the transfer failure occurrence current value tends to increase. As a result, the transferability of the photoreceptor 1 can be improved.

  The polyester resin can be obtained by, for example, condensation polymerization or co-condensation polymerization of alcohol and carboxylic acid. Examples of the alcohol used when synthesizing the polyester resin include dihydric alcohols and trihydric or higher alcohols. Examples of the dihydric alcohol include diols or bisphenols.

  Examples of diols include alkyl diol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol. Examples of the alkyl diol include alkyl diols having 1 to 6 carbon atoms. Specific examples of the alkyl diol having 1 to 6 carbon atoms include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol. 1,5-pentanediol, or 1,6-hexanediol.

  Examples of bisphenols include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, or bisphenol A propylene oxide adduct.

  Examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, or 1,3,5-trihydroxy Mention may be made of methylbenzene.

  Examples of the carboxylic acid used when synthesizing the polyester resin include divalent carboxylic acids and trivalent or higher carboxylic acids.

  Examples of divalent carboxylic acids include phthalic acid (eg, isophthalic acid, terephthalic acid, or orthophthalic acid), maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, Examples include azelaic acid, malonic acid, succinic acid, alkyl succinic acid, or alkenyl succinic acid. Specific examples of the alkyl succinic acid include n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, or isododecyl succinic acid. Specific examples of alkenyl succinic acid include n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, or isododecenyl succinic acid.

  Examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimer acid.

  Alcohol and carboxylic acid may be used individually by 1 type, respectively, and may be used in combination of 2 or more type. Further, the carboxylic acid may be used after being derivatized into an ester-forming derivative. The ester-forming derivative is, for example, an acid halide, an acid anhydride, or a lower alkyl ester. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms. Furthermore, these polyester resins may be used individually by 1 type, and may be used in combination of 2 or more type.

  The polyester resin is preferably a polycondensate of phthalic acid and an alkyl diol because the transferability of the photoreceptor 1 is easy to improve, and a polycondensate of one or both of terephthalic acid and isophthalic acid and an alkyl diol. It is more preferable that

  The content of the polyester resin is preferably 5% by mass or more and 30% by mass or less with respect to the mass of the photosensitive layer 3. When the content of the polyester resin is 5% by mass or more with respect to the mass of the photosensitive layer 3, the transferability of the photoreceptor 1 tends to be improved. When the content of the polyester resin is 30% by mass or less with respect to the mass of the photosensitive layer 3, it is easy to suppress the occurrence of image ghost in the formed image.

  The viscosity average molecular weight of the polyester resin is preferably 40000 or more, and more preferably 40000 or more and 52500 or less. When the viscosity average molecular weight of the polyester resin is 40000 or more, it is easy to improve the wear resistance of the photoreceptor 1. Further, when the viscosity average molecular weight of the polyester resin is 52500 or less, the polyester resin is easily dissolved in a solvent when the photosensitive layer 3 is formed, and the viscosity of the coating solution for the photosensitive layer 3 does not become too high. As a result, the photosensitive layer 3 can be easily formed. The number average molecular weight (Mn) of the polyester resin is preferably 5000 or more and 30000 or less, and more preferably 10,000 or more and 20000 or less.

  The photosensitive layer 3 may further contain another binder resin other than the polyester resin as a binder resin. Examples of another binder resin include a thermoplastic resin, a thermosetting resin, or a photocurable resin. Examples of the thermoplastic resin include polycarbonate resin, styrene resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic copolymer, Polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, urethane resin, polyarylate resin, polysulfone resin , Diallyl phthalate resin, ketone resin, polyvinyl butyral resin, or polyether resin. Examples of thermosetting resins include silicone resins, epoxy resins, phenolic resins, urea resins, melamine resins, or other crosslinkable thermosetting resins. As an example of a photocurable resin, an epoxy acrylic acid resin or a urethane-acrylic acid copolymer is mentioned. One of these other resins may be used alone, or two or more thereof may be used in combination.

  Among these other binder resins, a polycarbonate resin is preferable because the photosensitive layer 3 having an excellent balance of processability, mechanical properties, optical properties, and abrasion resistance can be easily obtained. Among the polycarbonate resins, bisphenol Z-type polycarbonate resin, bisphenol CZ-type polycarbonate resin, or bisphenol C-type polycarbonate resin is preferable because the transferability of the photoconductor 1 is easy to improve, and the following chemical formulas (Z), (C) or A resin represented by (CZ) is more preferable. In chemical formulas (Z), (C) and (CZ), the suffix of the repeating unit indicates the molar ratio of the repeating unit to which the suffix is attached relative to the total number of moles of the repeating unit in the resin.

  The molecular weight of another binder resin other than the polyester resin is preferably 40000 or more in terms of viscosity average molecular weight, and more preferably 40000 or more and 52500 or less. When the viscosity average molecular weight of another binder resin is 40000 or more, it is easy to improve the wear resistance of the photoreceptor 1. If the molecular weight of the other binder resin is 52500 or less, the other binder resin is easily dissolved in the solvent when the photosensitive layer 3 is formed, and the viscosity of the coating solution for the photosensitive layer 3 does not become too high. As a result, the photosensitive layer 3 can be easily formed.

  When the photosensitive layer 3 contains another binder resin in addition to the polyester resin as the binder resin, the content of the polyester resin is based on the total mass of the binder resin (polyester resin and another binder resin). It is preferable that they are 10 mass% or more and 60 mass% or less. There exists a tendency for the transferability of the photoreceptor 1 to improve that the content rate of a polyester resin is 10 mass% or more with respect to the total mass of binder resin. It becomes easy to suppress generation | occurrence | production of the image ghost in the image formed as the content rate of a polyester resin is 60 mass% or less with respect to the total mass of binder resin.

<2-5. Additives>
Examples of additives include deterioration inhibitors (eg, antioxidants, radical scavengers, singlet quenchers, or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, and dispersion stabilizers. Agents, waxes, acceptors, donors, surfactants, plasticizers, sensitizers, or leveling agents. Examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone, or a derivative thereof, an organic sulfur compound, or an organic phosphorus compound.

<3. Intermediate layer>
In the photoreceptor 1, the intermediate layer 4 (particularly the undercoat layer) is located between the conductive substrate 2 and the photosensitive layer 3, for example. The intermediate layer 4 contains, for example, inorganic particles and a resin (interlayer resin) used for the intermediate layer 4. It is considered that the presence of the intermediate layer 4 smoothes the flow of current generated when the photosensitive member 1 is exposed while suppressing an increase in resistance while maintaining an insulating state capable of suppressing the occurrence of leakage. .

  As the inorganic particles, for example, metal (for example, aluminum, iron, or copper), metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide, or zinc oxide) particles, or non-metal oxide (for example, , Silica) particles. These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

  The resin for the intermediate layer is not particularly limited as long as it is a resin that can be used as the resin for forming the intermediate layer 4.

  The intermediate layer 4 may contain various additives as long as the electrophotographic characteristics of the photoreceptor 1 are not adversely affected. The additives are the same as those for the photosensitive layer 3.

  The photoconductor 1 according to the first embodiment has been described above with reference to FIG. According to the photoreceptor 1 according to the first embodiment, the transferability of the photoreceptor 1 can be improved. According to the photoconductor 1 according to the first embodiment, an image having a desired image density is stabilized even when the value of the transfer current fluctuates due to fluctuations in external factors during image formation. Can be formed.

<Second Embodiment: Method for Manufacturing Photoconductor>
The second embodiment relates to a method for manufacturing the photoreceptor 1. The method for manufacturing the photoreceptor 1 includes, for example, a preparation process and an oxide film formation process. The method for manufacturing the photoreceptor 1 may further include a coating process and a photosensitive layer forming process.

<1. Preparation process>
In the preparation step, the conductive substrate 2 is prepared. The conductive substrate 2 contains aluminum or an aluminum alloy. In the preparation step, the conductive substrate 2 may be cleaned in advance. In the preparation step, the oxide film on the surface of the conductive substrate 2 may be removed in advance before the oxide film formation step. As a method for removing the oxide film, for example, a method of immersing the conductive substrate 2 in alkaline ionized water can be mentioned. The pH of the alkaline ionized water is preferably 9 or more and 12 or less. The time for immersing the conductive substrate 2 in alkaline ionized water is preferably 20 seconds or longer and 120 seconds or shorter. Further, in the preparation step, the conductive substrate 2 may be heated after removing the oxide film. For example, an oven is used to heat the conductive substrate 2. When heating the conductive substrate 2, the heating time is preferably 5 minutes or longer and 30 minutes or shorter.

<2. Oxide film formation process>
In the oxide film forming step, the surface of the conductive substrate 2 is oxidized. The method for oxidizing the surface of the conductive substrate 2 is not particularly limited. Since it is easy to adjust the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 to a desired value, in the oxide film forming step, the conductive substrate 2 is brought into contact with hot water so as to contact the surface of the conductive substrate 2. It is preferable to form an aluminum oxide film or an aluminum alloy oxide film. In other words, it is preferable that the surface of the conductive substrate 2 is oxidized using hot water.

  The method for bringing the conductive substrate 2 into contact with hot water is not particularly limited as long as the surface of the conductive substrate 2 is oxidized. Examples of the method of bringing the conductive substrate 2 into contact with hot water include a method of immersing the conductive substrate 2 in hot water, a method of spraying hot water onto the conductive substrate 2, or a conductive substrate under a hot water stream. The method of putting 2 is mentioned. A method of immersing the conductive substrate 2 in hot water is preferable because the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 can be easily adjusted.

  The temperature of the hot water is preferably 50 ° C. or higher and 70 ° C. or lower. When the temperature of the hot water is within such a range, the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 tends to be greater than 0.0% and not more than 15.0%.

  The time for contacting the conductive substrate 2 and hot water is preferably 1 second or more and 300 seconds or less. When the temperature of the hot water is within such a range, the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 tends to be greater than 0.0% and not more than 15.0%.

  As a suitable example for adjusting the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 to a desired value, the temperature of hot water is 50 ° C. or more and 60 ° C. or less. The contact time is 1 second or more and 10 seconds or less. As another preferred example for adjusting the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 to a desired value, the temperature of hot water is higher than 60 ° C. and not higher than 70 ° C. The time for contacting with hot water is 1 second or more and 5 seconds or less.

  As a more preferred example for adjusting the abundance ratio R of oxygen atoms on the surface of the conductive substrate 2 to a desired value, the temperature of hot water is 50 ° C. or higher and 60 ° C. or lower. The contact time is 5 seconds or more and 10 seconds or less.

  After contacting the conductive substrate 2 with hot water, the conductive substrate 2 may be heat-treated. The heat treatment of the conductive substrate 2 is performed, for example, in the air at a temperature of 120 ° C. or higher and 180 ° C. or lower for a period of 15 minutes or longer and 25 minutes or shorter.

<3. Application process>
In the coating step, a coating solution is applied to the conductive substrate 2 on which an aluminum oxide film or an aluminum alloy oxide film is formed. The method for applying the coating solution is not particularly limited as long as the coating solution can be uniformly applied on the conductive substrate 2. Examples of the method for applying the coating solution include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

  Since it is easy to adjust the thickness of the photosensitive layer 3 to a desired value, a dip coating method is preferable as a method of applying the coating solution. When the coating step is performed by a dip coating method, in the coating step, the conductive substrate 2 on which an aluminum oxide film or an aluminum alloy oxide film is formed is immersed in a coating solution. Subsequently, the immersed conductive substrate 2 is pulled up from the coating solution. As a result, the coating liquid is applied to the conductive substrate 2.

  The coating liquid contains at least a binder resin and a solvent. The coating solution contains, for example, at least a polyester resin as a binder resin. The coating solution may contain a charge generator, a hole transport agent, an electron transport agent, or various additives as necessary. The coating solution is prepared by dissolving or dispersing a binder resin and optional components (for example, a charge generator, a hole transport agent, an electron transport agent, or various additives) in a solvent.

  The solvent contained in the coating solution is not particularly limited as long as each component contained in the coating solution can be dissolved or dispersed. Examples of the solvent include alcohols (for example, methanol, ethanol, isopropanol, or butanol), aliphatic hydrocarbons (for example, n-hexane, octane, or cyclohexane), aromatic hydrocarbons (for example, benzene, toluene, Or xylene), halogenated hydrocarbons (eg, dichloromethane, dichloroethane, carbon tetrachloride, or chlorobenzene), ethers (eg, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, or diethylene glycol dimethyl ether), ketones (eg, acetone) , Methyl ethyl ketone, or cyclohexanone), esters (for example, ethyl acetate or methyl acetate), dimethylformaldehyde, N, N-dimethylformamide (D F), or dimethyl sulfoxide. These solvents may be used alone or in combination of two or more. Of these solvents, solvents other than halogenated hydrocarbons are preferred in order to improve the workability during production of the photoreceptor 1.

  The coating liquid is prepared by mixing each component with a solvent and dispersing each component in the solvent. For mixing or dispersing, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser is used.

  The coating liquid may contain, for example, a surfactant or a leveling agent in order to improve the dispersibility of each component and the smoothness of the formed photosensitive layer 3.

<4. Photosensitive layer forming step>
In the photosensitive layer forming step, the solvent contained in the coating solution applied to the conductive substrate 2 is removed to form the photosensitive layer 3.

  The method for removing the solvent contained in the coating solution is not particularly limited as long as the solvent in the coating solution can be evaporated. Examples of the method for removing the solvent include heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a vacuum dryer can be mentioned. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

  In addition, the manufacturing method of the photoreceptor 1 may further include one or both of a step of forming the intermediate layer 4 and a step of forming the protective layer 5 as necessary. In the step of forming the intermediate layer 4 and the step of forming the protective layer 5, a known method is appropriately selected.

  The method for manufacturing the photoreceptor 1 according to the second embodiment has been described above. According to the method for manufacturing the photoreceptor 1 according to the second embodiment, the photoreceptor 1 having excellent transferability can be manufactured.

<Third embodiment: Image forming apparatus>
The third embodiment relates to the image forming apparatus 6. Hereinafter, the image forming apparatus 6 according to the present embodiment will be described with reference to FIGS. 3 and 4.

  The image forming apparatus 6 includes a photoreceptor 1 as an image carrier. As described in the first embodiment, the photoreceptor 1 can improve the transferability of the photoreceptor 1. Therefore, the image forming apparatus 6 can improve transferability by including such a photoreceptor 1.

  Hereinafter, a case where the image forming apparatus 6 adopts the direct transfer method will be described as an example with reference to FIG. FIG. 3 is a schematic diagram illustrating a configuration of one aspect of the image forming apparatus 6.

  The image forming apparatus 6 includes the photoreceptor 1 described in the first embodiment, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit 26. The charging unit 27 charges the surface of the photoreceptor 1. The exposure unit 28 exposes the charged surface of the photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. The developing unit 29 develops the electrostatic latent image as a toner image. The transfer unit 26 transfers the toner image from the photoreceptor 1 to the transfer target 38. When the image forming apparatus 6 employs the direct transfer method, the transfer unit 26 corresponds to the transfer roller 41. The transfer body 38 corresponds to a recording medium (for example, paper P).

  The image forming apparatus 6 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 6 may be, for example, a monochrome image forming apparatus or a color image forming apparatus. The image forming apparatus 6 may be a tandem color image forming apparatus in order to form toner images of the respective colors using different color toners.

  Hereinafter, the image forming apparatus 6 will be described by taking a tandem color image forming apparatus as an example. The image forming apparatus 6 includes a plurality of photoreceptors 1 arranged in parallel in a predetermined direction and a plurality of developing units 29. Each of the plurality of developing units 29 is disposed to face the photoreceptor 1. Each of the plurality of developing units 29 includes a developing roller. The developing roller carries and conveys toner and supplies the toner to the surface of the corresponding photoreceptor 1.

  As shown in FIG. 3, the image forming apparatus 6 further includes a box-shaped device housing 7. In the device housing 7, a paper feeding unit 8, an image forming unit 9, and a fixing unit 10 are provided. The paper feed unit 8 feeds the paper P. The image forming unit 9 transfers the toner image based on the image data to the paper P while conveying the paper P fed from the paper feeding unit 8. The fixing unit 10 fixes the unfixed toner image transferred on the paper P by the image forming unit 9 to the paper P. Further, a paper discharge unit 11 is provided on the upper surface of the device housing 7. The paper discharge unit 11 discharges the paper P fixed by the fixing unit 10.

  The paper feed unit 8 includes a paper feed cassette 12, a first pickup roller 13, a plurality of paper feed rollers 14, and a registration roller pair 17. The paper feed cassette 12 is provided so as to be detachable from the device housing 7. Various sizes of paper P are stored in the paper feed cassette 12. The first pickup roller 13 is provided at the upper left position of the paper feed cassette 12. The first pickup roller 13 takes out the sheets P stored in the sheet feeding cassette 12 one by one. The plurality of paper feed rollers 14 transport the paper P picked up by the first pickup roller 13. The registration roller pair 17 temporarily waits for the paper P conveyed by the plurality of paper feed rollers 14 and then supplies the paper P to the image forming unit 9 at a predetermined timing.

  The paper feed unit 8 may further include a manual feed tray (not shown) and a second pickup roller 18 (see FIG. 4). The manual feed tray is attached to the left side surface of the device housing 7. The second pickup roller 18 takes out the paper P placed on the manual feed tray. The paper P taken out by the second pickup roller 18 is conveyed by a plurality of paper feed rollers 14 and is supplied to the image forming unit 9 by a registration roller pair 17 at a predetermined timing.

  The image forming unit 9 includes an image forming unit 19 and a transfer belt 40. The image forming unit 19 includes a black toner supply unit 22 and a cyan toner supply unit from the upstream side (left side in FIG. 3) to the downstream side in the rotation direction of the transfer belt 40 with respect to the black toner supply unit 22. 23, a magenta toner supply unit 24, and a yellow toner supply unit 25 are arranged in this order. The photosensitive member 1 is disposed at the center position of each unit 22, 23, 24, and 25. The photoreceptor 1 is disposed so as to be rotatable in the direction of an arrow (clockwise). Around each photoconductor 1, a charging unit 27, an exposure unit 28, a developing unit 29, and a transfer unit 26 are sequentially arranged from the upstream side in the rotation direction of each photoconductor 1 with respect to the charging unit 27. Yes.

  One or both of a cleaning device (not shown) and a static eliminator (not shown) may be provided on the upstream side of the charging unit 27 in the rotation direction of the photoreceptor 1. The cleaning device and the static eliminator respectively clean and neutralize the peripheral surface of the photoreceptor 1 after the transfer of the toner image onto the paper P is completed. The peripheral surface of the photoreceptor 1 cleaned and discharged by the cleaning device and the charge eliminator is sent to the charging unit 27 and newly charged. When the image forming apparatus 6 includes a cleaning device and a static eliminator, the charging unit 27, the exposure unit 28, the developing unit 29, the transfer unit 26, and the cleaning device with respect to the charging unit 27 from the upstream side in the rotation direction of each photoreceptor 1. , And the static eliminator.

  As already described, the charging unit 27 charges the surface (circumferential surface) of the photoreceptor 1. The charging polarity of the charging unit 27 is not particularly limited. In order to improve the sensitivity characteristics of the single-layer type photoreceptor 1, the charging unit 27 preferably charges the surface of the photoreceptor 1 to a positive polarity. That is, the charging polarity of the charging unit 27 is preferably positive.

  The charging unit 27 may be a non-contact method or a contact method. The non-contact charging unit 27 applies a voltage without contacting the photosensitive member 1. Examples of the non-contact charging unit 27 include a corona discharge type charging device, and more specifically, a corotron charger or a scorotron charger. The contact-type charging unit 27 is in contact with the photoreceptor 1 and applies a voltage. Examples of the contact-type charging unit 27 include a contact (proximity) discharge type charger, and more specifically, a charging roller or a charging brush.

  Examples of the charging roller include a charging roller that rotates following the rotation of the photoconductor 1 while in contact with the photoconductor 1. For example, at least a surface portion of the charging roller is formed of a resin. Specifically, the charging roller includes a core metal that is rotatably supported, a resin layer formed on the core metal, and a voltage application unit that applies a voltage to the core metal. The charging unit 27 including such a charging roller charges the surface of the photoreceptor 1 that is in contact with the resin through the resin layer when the voltage application unit applies a voltage to the cored bar.

  The resin that forms the resin layer of the charging roller is not particularly limited as long as the surface of the photoreceptor 1 can be charged satisfactorily. Specific examples of the resin forming the resin layer include a silicone resin, a urethane resin, and a silicone-modified resin. The resin layer may contain an inorganic filler.

  When the image forming apparatus 6 includes the contact-type charging unit 27, it is considered that discharge of active gas (for example, ozone or nitrogen oxide) generated from the charging unit 27 can be suppressed. As a result, it is considered that the deterioration of the photosensitive layer 3 due to the active gas is suppressed and the design considering the office environment can be achieved.

  The voltage applied by the charging unit 27 is not particularly limited. Examples of the voltage applied by the charging unit 27 include an AC voltage, a superimposed voltage obtained by superimposing the AC voltage on the DC voltage, or a DC voltage. Especially, it is preferable that the charging unit 27 applies only a DC voltage. The charging unit 27 that applies only a DC voltage has the following advantages compared to the charging unit 27 that applies an AC voltage or the charging unit 27 that applies a superimposed voltage obtained by superimposing an AC voltage on a DC voltage. When the charging unit 27 applies only a DC voltage, since the voltage value applied to the photoconductor 1 is constant, the surface of the photoconductor 1 is easily charged uniformly to a constant potential. Further, when the charging unit 27 applies only a DC voltage, the wear amount of the photosensitive layer 3 tends to decrease. As a result, it is considered that a suitable image can be formed.

  The voltage applied to the photosensitive member 1 by the charging unit 27 is preferably 1000 V or more and 2000 V or less, more preferably 1200 V or more and 1800 V or less, and particularly preferably 1400 V or more and 1600 V or less.

  Examples of the exposure unit 28 include an exposure device, and more specifically, a laser scanning unit. The exposure unit 28 exposes the charged surface of the photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. Specifically, the exposure unit 28 irradiates the circumferential surface of the photoreceptor 1 uniformly charged by the charging unit 27 with laser light based on image data input from a host device such as a personal computer. Thereby, an electrostatic latent image based on the image data is formed on the peripheral surface of the photoreceptor 1.

  The developing unit 29 develops the electrostatic latent image as a toner image. Specifically, the developing unit 29 supplies toner to the peripheral surface of the photoreceptor 1 on which the electrostatic latent image is formed, and forms a toner image based on the image data. An example of the developing unit 29 is a developing device.

  The transfer unit 26 (corresponding to the transfer roller 41) transfers the toner image formed on the surface of the photoreceptor 1 to the transfer target 38 (corresponding to the paper P). Specifically, the transfer belt 40 is an endless belt-like rotating body. The transfer belt 40 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of transfer rollers 41. The transfer belt 40 is arranged so that the circumferential surface of each photoconductor 1 abuts on the surface (contact surface) of the transfer belt 40. The transfer belt 40 is pressed against the photoconductor 1 by each transfer roller 41 disposed to face each photoconductor 1. While the transfer belt 40 is pressed, the transfer belt 40 rotates endlessly by the rotation of the driving roller 30, the driven roller 31, the backup roller 32, and the plurality of transfer rollers 41. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the transfer belt 40 endlessly. The driven roller 31, the backup roller 32, and the transfer roller 41 are rotatably provided. With the endless rotation of the transfer belt 40 by the driving roller 30, the driven roller 31, the backup roller 32, and the plurality of transfer rollers 41 are driven to rotate. The driven roller 31, the backup roller 32, and the plurality of transfer rollers 41 are driven to rotate and support the transfer belt 40. The paper P supplied from the registration roller pair 17 is sucked onto the transfer belt 40 by the suction roller 42. The sheet P adsorbed on the transfer belt 40 passes between each photoconductor 1 and the corresponding transfer roller 41 as the transfer belt 40 rotates.

  The transfer roller 41 transfers the toner image from the photoreceptor 1 to the paper P. The photosensitive member 1 is in contact with the paper P when the toner image is transferred. Specifically, each transfer roller 41 applies a transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the paper P adsorbed on the transfer belt 40. As a result, the toner image formed on the photoconductor 1 is transferred onto the paper P between each photoconductor 1 and the corresponding transfer roller 41. The transfer belt 40 circulates in the arrow (clockwise) direction by driving the driving roller 30. Accordingly, the paper P sucked on the transfer belt 40 sequentially passes between each photoconductor 1 and the corresponding transfer roller 41. When passing, the toner images of the corresponding colors formed on the respective photoreceptors 1 are sequentially transferred onto the paper P in the overcoated state.

  The fixing unit 10 fixes the unfixed toner image transferred to the paper P. The fixing unit 10 includes a heating roller 34 and a pressure roller 35. The heating roller 34 is heated by an energized heating element. The pressure roller 35 is disposed to face the heating roller 34, and the circumferential surface of the pressure roller 35 is pressed against the circumferential surface of the heating roller 34.

  The paper P on which the toner image is fixed is discharged from the paper discharge unit 11. The paper discharge unit 11 is formed by recessing the top of the device housing 7. A paper discharge tray 37 that receives the discharged paper P is provided at the bottom of the recessed portion. The image forming apparatus 6 that employs the direct transfer method according to one aspect of the embodiment has been described above with reference to FIG.

  Note that the image forming apparatus 6 of the present embodiment may adopt an intermediate transfer method. Hereinafter, an image forming apparatus 6 according to another aspect of the present embodiment will be described with reference to FIG. The image forming apparatus 6 shown in FIG. 4 employs an intermediate transfer method. In the image forming apparatus 6 illustrated in FIG. 4, the transfer unit 26 corresponds to the primary transfer roller 33 and the secondary transfer roller 21. The transfer target 38 corresponds to the intermediate transfer belt 20 and a recording medium (for example, paper P). In FIG. 4, elements corresponding to those in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.

  The intermediate transfer belt 20 is an endless belt rotating body. The intermediate transfer belt 20 is stretched around a driving roller 30, a driven roller 31, a backup roller 32, and a plurality of primary transfer rollers 33. The intermediate transfer belt 20 is disposed so that the peripheral surfaces of the plurality of photosensitive members 1 are in contact with the surface (contact surface) of the intermediate transfer belt 20.

  Further, the intermediate transfer belt 20 is pressed against the photoconductor 1 by a primary transfer roller 33 disposed to face each photoconductor 1. In the pressed state, the intermediate transfer belt 20 rotates endlessly in the arrow (counterclockwise) direction by the plurality of drive rollers 30. The driving roller 30 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 20 endlessly. The driven roller 31, the backup roller 32, and the plurality of primary transfer rollers 33 are rotatably provided. The driven roller 31, the backup roller 32, and the primary transfer roller 33 rotate following the endless rotation of the intermediate transfer belt 20 by the driving roller 30. The driven roller 31, the backup roller 32, and the primary transfer roller 33 are driven to rotate via the intermediate transfer belt 20 according to the main rotation of the driving roller 30 and support the intermediate transfer belt 20.

  The primary transfer roller 33 applies a primary transfer bias (specifically, a bias having a polarity opposite to the charging polarity of the toner) to the intermediate transfer belt 20. As a result, the toner image formed on each photoconductor 1 is sequentially transferred (primary transfer) to the intermediate transfer belt 20 that circulates between each photoconductor 1 and the primary transfer roller 33.

  The secondary transfer roller 21 applies a secondary transfer bias (specifically, a bias having a polarity opposite to the toner charging polarity) to the paper P. As a result, the toner image primarily transferred onto the intermediate transfer belt 20 is transferred onto the paper P between the secondary transfer roller 21 and the backup roller 32. As a result, an unfixed toner image is transferred onto the paper P.

  The unfixed toner image transferred to the paper P by the secondary transfer roller 21 is fixed to the paper P by a fixing process by heating when the paper P passes between the heating roller 34 and the pressure roller 35. Then, the paper P subjected to the fixing process is discharged to the paper discharge unit 11. In addition, a plurality of transport rollers 36 are disposed at appropriate positions between the fixing unit 10 and the paper discharge unit 11.

  The image forming apparatus 6 that employs the intermediate transfer method according to another aspect of the present embodiment has been described above with reference to FIG.

  As described above with reference to FIGS. 3 and 4, the image forming apparatus 6 according to this embodiment includes the photoreceptor 1 according to the first embodiment. The photoreceptor 1 is excellent in transferability. Therefore, the image forming apparatus 6 according to this embodiment can improve the transferability of the photoreceptor 1.

<Fourth embodiment: Process cartridge>
The fourth embodiment relates to a process cartridge. The process cartridge according to the present embodiment includes, for example, the photoreceptor 1 according to the first embodiment that is unitized. The process cartridge may be designed to be detachable from the image forming apparatus 6 according to the third embodiment. For example, in addition to the photosensitive member 1, the process cartridge is selected from the group consisting of the charging unit 27, the exposure unit 28, the developing unit 29, the transfer unit 26, the cleaning device, and the static eliminator described in the third embodiment. A configuration in which at least one is unitized is adopted.

  The process cartridge according to the present embodiment has been described above. The process cartridge according to the present embodiment includes the photoreceptor 1 according to the first embodiment. The photoreceptor 1 is excellent in transferability. Therefore, the process cartridge according to the present embodiment can improve the transferability of the photoreceptor 1. Furthermore, since such a process cartridge is easy to handle, when the sensitivity characteristics of the photoconductor 1 deteriorate, the process cartridge including the photoconductor 1 can be easily and quickly replaced.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the scope of the examples.

<1. Photosensitive Material>
The following charge generator, hole transport agent, electron transport agent, and binder resin were prepared as materials for forming the photosensitive layer of the photoreceptor.

  A compound (CGM-1X) was prepared as a charge generator. The compound (CGM-1X) was a metal-free phthalocyanine represented by the chemical formula (CGM-1) described in the first embodiment. Furthermore, the crystal structure of the compound (CGM-1X) was X-type.

  The compound (HTM-3) described in the first embodiment was prepared as a hole transport agent.

  As electron transport agents, the compounds (ETM-1) to (ETM-6) described in the first embodiment were prepared.

  A polyester resin (R1a) was prepared as a binder resin. The polyester resin (R1a) was a polycondensate of terephthalic acid, isophthalic acid, and alkyldiol (“Byron (registered trademark) 200” manufactured by Toyobo Co., Ltd., number average molecular weight (Mn) 17,000).

  A polycarbonate resin (Za) was prepared as a binder resin. The polycarbonate resin (Za) was a polycarbonate resin represented by the chemical formula (Z) described in the first embodiment.

<2. Manufacture of photoconductor>
Photoconductors (A-1) to (A-22) and (B-1) to (B-6) were produced using the material for forming the photosensitive layer of the prepared photoconductor.

<2-1. Production of photoconductor (A-1)>
First, a preparation process was performed. Specifically, an aluminum conductive substrate having a diameter of 30 mm, a length of 254 mm, and a thickness of 0.7 mm was prepared. This conductive substrate was subjected to alkali treatment. Specifically, the conductive substrate was immersed in alkaline ionized water having a pH of 11 for 20 minutes. Thereby, the oxide film on the surface of the conductive substrate was removed.

  Next, an oxide film forming step was performed. Specifically, the conductive substrate was immersed in hot water at 60 ° C. for 10 seconds. Thus, an aluminum oxide film was formed again on the surface of the conductive substrate. The conductive substrate was removed from the hot water, and the conductive substrate was naturally dried. The conductive substrate was then heated at 120 ° C. for 2 minutes using an oven. Thus, a conductive substrate having an aluminum oxide film on the surface of the conductive substrate was obtained. The abundance ratio R of oxygen atoms on the surface of the obtained conductive substrate was measured by the method described later.

  Next, the coating process was performed. First, a coating solution was prepared. 5 parts by mass of a compound (CGM-1X) as a charge generating agent, 60 parts by mass of a compound (HTM-3) as a hole transporting agent, 35 parts by mass of a compound (ETM-1) as an electron transporting agent, and a binder 90 parts by mass of a polycarbonate resin (Za) as a resin, 10 parts by mass of a polyester resin (R1a), and 800 parts by mass of tetrahydrofuran as a solvent were put in a container. The contents of the container were mixed and dispersed for 50 hours using a ball mill to obtain a coating solution.

  Next, using a dip coating method, a coating solution was applied on the conductive substrate obtained in the oxide film forming step, and a coating film was formed on the conductive substrate. Specifically, the conductive substrate was immersed in the coating solution. The immersed conductive substrate was pulled up from the coating solution, and the coating solution was applied to the conductive substrate.

  Next, a photosensitive layer forming step was performed. Specifically, the conductive substrate coated with the coating solution was dried with hot air at 100 ° C. for 40 minutes. As a result, the solvent (tetrahydrofuran) contained in the coating solution applied to the conductive substrate was removed. As a result, a photosensitive layer was formed on the conductive substrate. Thereby, the photoreceptor (A-1) was obtained.

<2-2. Production of photoconductors (A-2) to (A-22) and (B-1) to (B-6)>
Except for the following changes, the photoconductors (A-2) to (A-22) and (B-1) to (B-6) were prepared in the same manner as in the production of the photoconductor (A-1). Manufactured.

  In the oxide film forming step, the temperature shown in Table 1 is changed from the temperature of hot water and the immersion time in hot water (time to contact with hot water) from 60 ° C. and 10 seconds in the production of the photoreceptor (A-1). Changed to immersion time. Thereby, the abundance ratio R of oxygen atoms on the surface of the conductive substrate was changed from 12.0% of the photoreceptor (A-1) to the ratio shown in Table 1.

  In the coating process, the electron transport agent used for the preparation of the coating solution was changed from the compound (ETM-1) in the production of the photoreceptor (A-1) to the type of compound shown in Table 1.

  In the coating step, the addition amount of the polycarbonate resin (Za) as the binder resin used for the preparation of the coating solution was changed from 90 parts by mass in the production of the photoreceptor (A-1) to the addition amount shown in Table 1. Furthermore, the addition amount of the polyester resin (R1a) as a binder resin was changed from 10 parts by mass in the production of the photoreceptor (A-1) to the addition amount shown in Table 1. Thereby, the content rate of the polyester resin with respect to the mass of a photosensitive layer was changed into the content rate shown in Table 1 from 5 mass% of a photoreceptor (A-1). In addition, the mass of the photosensitive layer was the total mass of the charge generator, the hole transport agent, the electron transport agent, and the polycarbonate resin and the polyester resin as the binder resin.

  By appropriately changing the viscosity of the coating solution used in the coating step and the speed at which the conductive substrate is pulled up from the coating solution, the thickness (film thickness) of the photosensitive layer is changed from 25.0 μm of the photoreceptor (A-1). The thickness was changed as shown in Table 1.

<3. Measurement of oxygen atom abundance ratio R on the surface of the conductive substrate>
In the production of each photoconductor, the oxygen atom abundance ratio R on the surface of the conductive substrate was measured by the following method for the conductive substrate obtained in the oxide film forming step. First, the surface of the conductive substrate was subjected to energy dispersive X-ray spectroscopy (EDX) using an energy dispersive X-ray spectroscope (“JEMOL JSM-6380LV” manufactured by JEOL Ltd.). It was measured. The measurement conditions were set at an acceleration voltage of 5 keV. Thereby, the oxygen atom concentration (A _O , unit: atomic%) and the aluminum atom concentration (A _Al , unit: atomic%) on the surface of the conductive substrate were measured. Based on the measured oxygen atom concentration and aluminum atom concentration, the abundance ratio R of oxygen atoms was calculated according to the following formula (1). Table 1 shows the calculated oxygen atom abundance ratio R.
R = 100 × A _O / (A _O + A _Al ) (1)

<4. Measurement of photosensitive layer thickness>
The thickness of the photosensitive layer of each photoconductor was measured using an eddy current film thickness meter (“Fischer Scope MMS 3AM” manufactured by Fischer Instruments Co., Ltd.). Table 1 shows the measured thickness (film thickness) of the photosensitive layer.

<5. Evaluation of transferability>
An image A was formed on a sheet while changing the current applied by the transfer roller to the photoconductor using an evaluation machine equipped with each photoconductor and toner. Image A was a solid image of 30 mm × 30 mm. As an image forming condition, the current applied by the transfer roller to the photoconductor was set in the range of −2 μA to −40 μA. Specifically, the transfer current of the transfer roller was decreased from −2 μA to −2 μA, and an image A was formed on the paper at each transfer current. The image density (ID) of image A formed on the paper was measured using a Macbeth reflection densitometer (“SpectroEye (registered trademark)” sold by Sakata Inx Engineering Co., Ltd.). The transfer current when the measured image density was 1.20 or less was defined as a transfer failure occurrence current value (C ₂ , unit: −μA). Based on the measured transfer failure occurrence current value, the transferability of the photoreceptor was evaluated according to the following evaluation criteria. Table 2 shows the measured transfer failure occurrence current value (C ₂ , unit: −μA) and the evaluation result of the transferability of the photoreceptor. Note that the larger the absolute value (C ₂ ) of the transfer failure occurrence current value, the better the transferability of the photoconductor.
(Evaluation criteria for transferability)
Evaluation A: The absolute value (C ₂ ) of the transfer failure occurrence current value was 20 μA or more.
Evaluation B: The absolute value (C ₂ ) of the transfer failure occurrence current value was less than ₂₀ μA.

<6. Image Evaluation (Image Ghost)>
In order to stabilize the operation of the photoconductor of the evaluation machine, the alphabet image was printed for 1 hour. Subsequently, one image B was printed. Image B was an image composed of a donut-shaped white pattern. The donut-shaped white pattern was composed of a pair of two concentric circles. The image density of the image portion of image B (the portion other than the donut-shaped white pattern) was 100%. Image B was equivalent to one round of the photoreceptor. Subsequently, one sheet of half-tone image C (image density 12.5%) was printed as an image ghost evaluation sample. Image C corresponds to the second round of the photoreceptor.

The obtained sample for evaluation was visually observed, and the presence or absence of an image ghost derived from the image B was observed. Based on the observation results, image evaluation related to the image ghost was performed according to the following evaluation criteria. Table 2 shows the evaluation results regarding the image ghost.
(Evaluation criteria for image evaluation related to image ghost)
Evaluation A: Image ghost was not confirmed.
Evaluation B: Image ghost was confirmed.

<7. Image evaluation (black dots)>
The photoconductor was mounted on an evaluation machine. Image formation was performed in an environment of a temperature of 32.5 ° C. and a humidity of 80%. In order to stabilize the operation of the photoconductor of the evaluator, 1000 alphabet images were printed, and then the evaluator was left overnight. One image D was printed and used as a black spot evaluation sample. Image D was a full blank image. The obtained sample for evaluation was visually observed to observe the presence or absence of black spots. Based on the observation results, image evaluation on black spots was performed according to the following evaluation criteria. Table 2 shows the evaluation results regarding the black spots.
(Evaluation criteria for image evaluation for sunspots)
Evaluation A: A black spot was not confirmed.
Evaluation B: A black spot was confirmed.

<8. Overall evaluation>
From the results of the evaluation of the transferability of the photoconductor, the image evaluation relating to the image ghost, and the image evaluation relating to the black spot, the overall evaluation of the photoconductor was performed according to the following evaluation criteria. The results of comprehensive evaluation are shown in Table 2.
(Evaluation criteria for comprehensive evaluation)
A (particularly good): The transferability of the photoreceptor was evaluated as A. Furthermore, the image evaluation regarding the image ghost and the image evaluation regarding the black spot were also A.
○ (Good): The transferability of the photoreceptor was evaluated as A. However, one or both of the image evaluation regarding the image ghost and the image evaluation regarding the black spot were B.
X (defect): The transferability of the photoconductor was evaluated as B.

  In Table 1, “R”, “ETM”, and “content ratio” indicate the content ratio of the polyester resin relative to the mass of the oxygen atom, the electron transport agent, and the photosensitive layer on the surface of the conductive substrate. Photoconductors (A-1) to (A-22) are examples. Photoconductors (B-1) to (B-6) are comparative examples.

  As shown in Table 1, in the photoreceptors (A-1) to (A-22), the photosensitive layer contained at least a polyester resin as a binder resin. The thickness of the photosensitive layer was 25.0 μm or less. The conductive substrate contained aluminum or an aluminum alloy. The surface of the conductive substrate had an aluminum oxide film or an aluminum alloy oxide film. The abundance ratio R of oxygen atoms on the surface of the conductive substrate was greater than 0.0% and 15.0% or less. Therefore, as shown in Table 2, these photoconductors were excellent in transferability.

  As shown in Table 1, photoconductors (A-1) to (A-5), (A-7) to (A-11), (A-13) to (A-17), and (A-19) ) To (A-22), the polyester resin content was 5% by mass or more and 30% by mass or less based on the mass of the photosensitive layer. Therefore, as shown in Table 2, these photoconductors were excellent in transferability, and the occurrence of image ghosts in the formed image was suppressed.

  As shown in Table 1, in the photoreceptors (A-1) to (A-18) and (A-20) to (A-22), the thickness of the photosensitive layer is 10.0 μm or more and 25.0 μm or less. there were. Therefore, as shown in Table 2, these photoconductors were excellent in transferability, and the occurrence of black spots in the formed image was suppressed.

  As shown in Table 1, the photosensitive layers of the photoreceptors (B-1) to (B-3) did not contain a polyester resin. In the photoreceptor (B-4), the oxygen atom existing ratio R on the surface of the conductive substrate exceeded 15.0%. In the photoreceptors (B-5) and (B-6), the thickness of the photosensitive layer exceeded 25.0 μm. Therefore, as shown in Table 2, these photoconductors were inferior in transferability.

  From the above, it has become clear that the photoreceptor according to the present invention is excellent in transferability. Further, it has been clarified that an image forming apparatus provided with such a photoreceptor is excellent in transferability.

  The photoreceptor according to the present invention can be suitably used in an electrophotographic image forming apparatus.

1 Photoconductor (Single-layer type electrophotographic photoconductor)
2 Conductive substrate 3 Photosensitive layer 6 Image forming apparatus 26 Transfer unit 27 Charging unit 28 Exposure unit 29 Development unit 38 Transfer object

Claims (12)

A single-layer electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer,
The photosensitive layer contains at least a polyester resin as a binder resin,
The photosensitive layer has a thickness of 25.0 μm or less,
The conductive substrate contains aluminum or an aluminum alloy,
The surface of the conductive substrate has the aluminum oxide film or the aluminum alloy oxide film,
The single layer type electrophotographic photosensitive member, wherein an abundance ratio R of oxygen atoms on the surface of the conductive substrate calculated from the following mathematical formula (1) is greater than 0.0% and equal to or less than 15.0%.
R = 100 × A _O / (A _O + A _Al ) (1)
(In Formula (1),
A _O is the oxygen atom concentration obtained by measuring the surface of the conductive substrate using energy dispersive X-ray spectroscopy,
A _Al is the aluminum atom concentration obtained by measuring the surface of the conductive substrate using energy dispersive X-ray spectroscopy. )   2. The single-layer electrophotographic photosensitive member according to claim 1, wherein the content of the polyester resin is 5% by mass or more and 30% by mass or less with respect to the mass of the photosensitive layer.   The single-layer electrophotographic photosensitive member according to claim 1, wherein the polyester resin is a polycondensate of phthalic acid and an alkyl diol.   The single-layer electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a thickness of 10.0 μm or more and 25.0 μm or less. The photosensitive layer further contains an electron transport agent,
The electron transport agent is a compound represented by the following general formula (1), (2), (3), (4), (5) or (6). 1. A single-layer electrophotographic photosensitive member according to 1.

(In the general formulas (1), (2), (3), (4) and (5),
R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ are each independently a hydrogen atom, cyano A group, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkoxy group which may have a substituent, an alkoxycarbonyl group which may have a substituent, a substituent An aralkyl group which may have, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent;
R ₃₃ is a halogen atom, a hydrogen atom, a cyano group, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkoxy group that may have a substituent, or a substituent. And an optionally substituted alkoxycarbonyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. )

(In the general formula (6),
R ₆₁ each independently represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 7 to 12 carbon atoms. An aralkyl group, or an aryl group having 6 to 12 carbon atoms that may have a substituent,
R ₆₂ represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or An aryl group having 6 to 12 carbon atoms which may have a substituent or a heterocyclic group which may have a substituent. ) In the general formulas (1), (2), (3), (4) and (5),
R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₃₁ , R ₃₂ , R ₄₁ , R ₄₂ , R ₅₁ , R ₅₂ , and R ₅₃ are each independently a hydrogen atom, phenyl Represents an alkoxy group having 1 to 6 carbon atoms, a phenyl group optionally having an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. ,
R ₃₃ represents a halogen atom,
In the general formula (6),
R ₆₁ each independently represents an alkyl group having 1 to 6 carbon atoms,
The single-layer electrophotographic photosensitive member according to claim 5, wherein R ₆₂ represents an aryl group having 6 to 12 carbon atoms. The single-layer electrophotographic photosensitive member according to claim 5 or 6, wherein the electron transfer agent is a compound represented by the following chemical formula (ETM-6).

Preparing the conductive substrate containing the aluminum or the aluminum alloy; and
An oxide film for forming the aluminum oxide film or the aluminum alloy oxide film on the surface of the conductive substrate by bringing the conductive substrate containing the aluminum or the aluminum alloy into contact with hot water Forming process, and
The temperature of the hot water is 50 ° C. or higher and 70 ° C. or lower,
The method for producing a single-layer electrophotographic photosensitive member according to any one of claims 1 to 7, wherein a time for contacting the conductive substrate and the hot water is 1 second or more and 300 seconds or less. The temperature of the hot water is 50 ° C. or more and 60 ° C. or less, and the time for contacting the conductive substrate and the hot water is 1 second or more and 10 seconds or less,
The single layer type according to claim 8, wherein the temperature of the hot water is higher than 60 ° C and not higher than 70 ° C, and the time for contacting the conductive substrate and the hot water is not shorter than 1 second and not longer than 5 seconds. A method for producing an electrophotographic photoreceptor.   A process cartridge comprising the single-layer electrophotographic photosensitive member according to claim 1. The single-layer electrophotographic photosensitive member according to any one of claims 1 to 7,
A charging unit that charges the surface of the single-layer electrophotographic photosensitive member;
Exposing the charged surface of the single-layer electrophotographic photosensitive member to form an electrostatic latent image on the surface of the single-layer electrophotographic photosensitive member; and
A developing unit for developing the electrostatic latent image as a toner image;
An image forming apparatus comprising: a transfer unit that transfers the toner image from the single-layer electrophotographic photosensitive member to a transfer target.   The image forming apparatus according to claim 11, wherein the charging unit charges the surface of the single-layer electrophotographic photosensitive member to a positive polarity.

Images