CN109298606B - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

The invention provides an electrophotographic photoreceptor, a process cartridge and an image forming apparatus. An electrophotographic photoreceptor includes a conductive substrate and a photosensitive layer. The conductive matrix comprises aluminum or an aluminum alloy. The photosensitive layer is a single layer of photosensitive layer. The photosensitive layer contains a charge generator, a hole transporting agent, an electron transporting agent, a binder resin, and an additive. The additive comprises a carboxylic acid anhydride. The change value of the relative dielectric constant is 1.00 or more. The change in relative dielectric constant is obtained by charging the photosensitive layer with a light having a wavelength of 780nm and an exposure of 1.2. mu.J/cm²The charged photosensitive layer is exposed to light, a plurality of relative dielectric constants are calculated when a current of-30 μ A to-10 μ A flows into the exposed region, and the difference between the maximum value and the minimum value of the relative dielectric constants, that is, the change value of the relative dielectric constants is obtained.

Description

Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Technical Field

The invention relates to an electrophotographic photoreceptor, a process cartridge and an image forming apparatus.

Background

Electrophotographic photoreceptors are used as image carriers in electrophotographic image forming apparatuses (e.g., printing apparatuses and multifunction machines). Generally, an electrophotographic photoreceptor includes a photosensitive layer. The photosensitive layer contains, for example: a charge generating agent, a charge transporting agent (more specifically, a hole transporting agent or an electron transporting agent), and a resin (binding resin) that binds them. For example, an electrophotographic photoreceptor contains a charge generating agent and a charge transporting agent in the same layer (photosensitive layer), and the layer has both functions of charge generation and charge transport. Such an electrophotographic photoreceptor is called a single-layer type electrophotographic photoreceptor.

As an electron transport agent for electrophotographic photoreceptors, a succinic anhydride compound having a specific structure is known.

Disclosure of Invention

However, the succinic anhydride-based compound having a specific structure cannot sufficiently improve the toner image transferability of the electrophotographic photoreceptor.

In view of the above-described problems, an object of the present invention is to provide an electrophotographic photoreceptor having excellent toner image transferability. Further, an object of the present invention is to provide a process cartridge and an image forming apparatus having excellent toner image transferability.

The electrophotographic photoreceptor of the present invention includes a conductive substrate and a photosensitive layer. The conductive matrix comprises aluminum or an aluminum alloy. The photosensitive layer is a single layer of photosensitive layer. The photosensitive layer includes: a charge generating agent, a hole transporting agent, an electron transporting agent, a binder resin, and an additive. The additive comprises a carboxylic acid anhydride. The change value of the relative dielectric constant is 1.00 or more. The change value of the relative dielectric constant is obtained by charging the photosensitive layer with a wavelength of 780nm and an exposure amount of 1.2 muJ/cm²The charged photosensitive layer is exposed to light, a plurality of relative dielectric constants are calculated when a current of-30 μ A to-10 μ A flows into the exposed region, and the difference between the maximum value and the minimum value of the relative dielectric constants is obtained as the change value of the relative dielectric constants.

The process cartridge of the present invention includes the electrophotographic photoreceptor.

An image forming apparatus of the present invention includes: an image carrier, a charging section, an exposure section, a developing section, and a transfer section. The image bearing member is the electrophotographic photoreceptor. The charging unit charges a surface of the image carrier. The charging polarity of the charging portion is positive. The exposure section exposes the surface of the charged image carrier to form an electrostatic latent image. The developing section develops the electrostatic latent image into a toner image. The transfer section transfers the toner image from the surface of the image carrier to a recording medium.

The electrophotographic photoreceptor of the present invention is excellent in toner image transferability. The process cartridge and the image forming apparatus of the present invention are excellent in toner image transferability.

Drawings

Fig. 1(a), (b), and (c) are schematic cross-sectional views of the structure of the electrophotographic photoreceptor according to the first embodiment.

Fig. 2 shows a measuring device.

Fig. 3 is a schematic configuration diagram of an image forming apparatus according to a second embodiment.

Fig. 4 shows an image in which an image failure occurs.

Fig. 5 shows an evaluation image.

Detailed Description

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. Note that, although the description may be omitted as appropriate, the gist of the present invention is not limited thereto.

Hereinafter, the compound and its derivatives may be collectively referred to by adding "class" to the compound name. When a "class" is added after the compound name to indicate the polymer name, the repeating unit indicating the polymer is derived from the compound or a derivative thereof. The group "may have a certain group" means a group "may be substituted with a certain group", the group "may have a halogen atom" means a group "may be substituted with a halogen atom", and the group "may have a halogen atom" means a group "may be substituted with a halogen atom".

Hereinafter, unless otherwise specified, halogen atoms, hetero atoms, C1-C6 alkyl groups, C1-C5 alkyl groups, C1-C3 alkyl groups, C2-C4 alkynyl groups, C6-C14 aryl groups, C6-C14 aromatic hydrocarbon rings, C3-C14 aromatic heterocyclic rings, C1-C6 alkoxy groups and C1-C3 alkoxy groups each have the following meanings.

Halogen atoms such as: fluorine atom, chlorine atom, bromine atom or iodine atom.

Hetero atoms such as: an oxygen atom, a nitrogen atom or a sulfur atom.

The C1-C6 alkyl group is linear or branched and unsubstituted. C1-C6 alkyl such as: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl or n-hexyl.

The C1-C5 alkyl group is linear or branched and unsubstituted. C1-C5 alkyl such as: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, or neopentyl.

The C1-C3 alkyl group is linear or branched and unsubstituted. C1-C3 alkyl such as: methyl, ethyl, n-propyl or isopropyl.

C2-C4 alkynyl is unsubstituted. C2-C4 alkynyl, for example: ethynyl, propynyl (more specifically, Prop-1-yn-1-yl (Prop-1-yn-1-yl) or Prop-2-yn-1-yl (Prop-2-yn-1-yl)) or butynyl (more specifically, But-1-yn-1-yl (But-l-yn-l-yl), But-1-yn-2-yl (But-l-yn-2-yl) or But-2-yn-1-yl (But-2-yn-1-yl), and the like).

The C6-C14 aryl group is unsubstituted. C6-C14 aryl, for example: unsubstituted C6-C14 aromatic monocyclic hydrocarbon group, unsubstituted C6-C14 aromatic condensed bicyclic hydrocarbon group or unsubstituted C6-C14 aromatic condensed tricyclic hydrocarbon group. C6-C14 aryl, for example: phenyl, naphthyl, anthryl or phenanthryl.

The C6-C14 aromatic hydrocarbon ring is unsubstituted. C6-C14 aromatic hydrocarbon ring such as: a benzene, naphthalene, anthracene or phenanthrene ring.

The C3-C14 heteroaromatic ring is unsubstituted and contains 1 or several heteroatoms. C3-C14 heteroaromatic ring such as monocyclic or polycyclic aromatic heterocyclic ring. Monocyclic aromatic heterocycles are for example: a pyrrole ring, furan ring, thiophene ring, imidazole ring, pyrazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, pyridine ring, pyrimidine ring or pyrazine ring. Polycyclic aromatic heterocycles are, for example: a quinoline ring, an isoquinoline ring, an indole ring, a benzofuran ring or an acridine ring.

The C1-C6 alkoxy group is linear or branched and unsubstituted. C1-C6 alkoxy, for example: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, s-butoxy, t-butoxy, n-pentyloxy, t-pentyloxy or n-hexyloxy.

The C1-C3 alkoxy group is linear or branched and unsubstituted. C1-C3 alkoxy, for example: methoxy, ethoxy, n-propoxy or isopropoxy.

< first embodiment: electrophotographic photoreceptor

The structure of an electrophotographic photoreceptor (hereinafter, referred to as a photoreceptor) according to the first embodiment will be described with reference to fig. 1. Fig. 1 is a schematic sectional view of the structure of the photoreceptor 1. The photoreceptor 1 includes a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 is a single layer of the photosensitive layer 3. The photosensitive layer 3 is directly or indirectly provided on the conductive substrate 2. For example, as shown in fig. 1(a), the photosensitive layer 3 may be provided directly on the conductive substrate 2. For example, as shown in fig. 1(b), the intermediate layer 4 may be provided between the conductive substrate 2 and the photosensitive layer 3. As shown in fig. 1(a) and 1(b), the photosensitive layer 3 may be exposed as an outermost layer. As shown in fig. 1(c), the photosensitive layer 3 may be provided with a protective layer 5.

The photoreceptor 1 according to the first embodiment is excellent in toner image transferability. The reason is presumed as follows.

First, for easy understanding, the decrease in transferability will be described. An image forming apparatus of an electrophotographic system includes, for example: an image carrier (photoreceptor), a charging section, an exposure section, a developing section, and a transfer section. The transfer section transfers the toner image from the photoreceptor 1 to a recording medium. A transfer bias having a polarity opposite to that of the toner image is applied to the transfer section. In this case, when the surface potential (post-exposure potential) of the exposure region of the photoreceptor 1 is lowered (for example, when the post-exposure potential is less than-30V), electrostatic attraction easily acts between the toner image and the photosensitive layer surface 3 a. Then, the toner image transfer efficiency from the photoreceptor 1 to the recording medium may be reduced. Such a decrease in the transferability of the toner image is particularly likely to occur in an environment of high temperature and high humidity (more specifically, a temperature of 32.5 ℃ and a relative humidity of 80% RH).

In the photoreceptor 1 according to the first embodiment, the photosensitive layer 3 contains a carboxylic anhydride as an additive, and the change value of the relative permittivity of the photosensitive layer 3 is 1.00 or more. When the photosensitive layer 3 contains a carboxylic anhydride as an additive and the change value of the relative dielectric constant of the photosensitive layer 3 is 1.00 or more, the surface potential of the photosensitive layer 3 is less likely to be charged to the opposite polarity to the toner image even if a transfer bias is applied to the transfer portion. In this case, the electrostatic attraction is less likely to act between the surface potential of the photosensitive layer 3 and the toner image. Therefore, the photoreceptor 1 according to the first embodiment is considered to have excellent toner image transferability.

(value of change in relative permittivity)

The change value of the relative dielectric constant of the photosensitive layer 3 is 1.00 or more, preferably 1.60 or more, and more preferably 1.60 or more and 7.00 or less.

The change value of the relative dielectric constant of the photosensitive layer 3 is obtained by charging the photosensitive layer 3 with a wavelength of 780nm and an exposure amount of 1.2. mu.J/cm²The charged photosensitive layer 3 is exposed to light, a plurality of relative dielectric constants are calculated when a current of-30 μ A to-10 μ A flows into the exposed region, and the difference between the maximum value and the minimum value of the relative dielectric constants, that is, the change value of the relative dielectric constants is obtained. In addition, the exposure region means: on the surface of the photosensitive layer 3, the wavelength was 780nm and the exposure amount was 1.2. mu.J/cm²The area irradiated with the light for exposure.

A method of calculating the change value of the relative dielectric constant of the photosensitive layer 3 will be described in detail. Change value Delta epsilon of relative dielectric constant of photosensitive layer 3_rCalculated by equation (1).

Change value of relative dielectric constant Deltaε_r＝ε_r ^MAX-ε_r ^MIN……(1)

In equation (1), ε_r ^MAXAnd epsilon_r ^MINRespectively, a plurality of relative dielectric constants ε calculated when a negative current applied to the surface 3a of the photosensitive layer is changed_rMaximum and minimum values of (1).

Relative dielectric constant ε_rExpressed by equation (2).

[ number 1 ]

In the equation (2), Q represents the amount of electricity (amount of charge, unit:. mu.C) in a predetermined area S of the photosensitive layer surface 3a charged by the grid electrode type charging unit (Scorotron). d represents the film thickness (unit: μm) of the photosensitive layer 3. S represents a predetermined area (388.55 cm) charged in the photosensitive layer surface 3a²). V represents the surface potential (charged potential V) of the photosensitive layer 3 charged by the grid electrode type charging part (Scorotron)₀) Surface potential (post-transfer potential V) of the negatively charged photosensitive layer 3 after exposure to the charged photosensitive layer 3_t) Difference of difference (V)₀-V_t)。ε₀Which represents the dielectric constant of a vacuum.

The film thickness of the photosensitive layer 3 was measured using a film thickness measuring apparatus ("FISCHERSCOPE (registered trademark) mms (registered trademark) manufactured by helmutcher) and was measured at a temperature of 23 ℃ and a relative humidity of 50% RH.

The quantity of electricity Q was measured by a small portable ammeter/voltmeter (model 2051 manufactured by Yokogawa Test & Measurement). A small portable ammeter was connected in series between a high-voltage substrate of the evaluation apparatus and a negative charging roller described later based on fig. 2, and measurement was performed in a state in which the amount of electricity on the photosensitive layer surface 3a could be monitored at any time during image formation, and at a temperature of 23 ℃ and a relative humidity of 50% RH.

Charged potential V₀And post-transfer potential V_tThe measurement was performed using the measurement apparatus shown in fig. 2. Fig. 2 shows a measuring device 20. The measurement device 20 includes: there are a grid electrode type charging section (Scorotron)10, a first potential probe 12, an exposure unit 14, a negative charging roller 16, and a second potential probe 18. The photoreceptor 1 is provided in the measuring device 20. In the measuring device 20, with the grid electrode type charging section (Scorotron)10 as a reference, the following are provided along the rotation direction of the photoreceptor 1: a first potential probe 12, an exposure unit 14, a negative charging roller 16, and a second potential probe 18. Also, the measurement environment was a temperature of 23 ℃ and a relative humidity of 50% RH.

More specifically, the above-described respective components in the apparatus are set as follows (starting point-ending point: required time). Charged position a-first measurement position B: 0.092 seconds; first measurement position B-exposure position C: 0.092 seconds; exposure position C-charging position D: 0.084 second. The required time represents: when the photoreceptor 1 rotates at 109rpm, the specific region on the photosensitive layer surface 3a passes the above-mentioned 2 points (starting point to end point) for a while.

The charging position a represents: the intersection between the line segment of the wire W having the grid electrode type charging section 10 and the photosensitive layer surface 3a is located at the rotation center O of the photoreceptor 1. The first measurement position B indicates a position where the first potential probe 12 measures the surface potential of the photosensitive layer 3. The exposure position C indicates: the exposure unit 14 irradiates light to a position on the photosensitive layer surface 3a where exposure is performed. The charging position D indicates a contact point between the photoreceptor 1 and the negative charging roller 16. The second measurement position E represents: the second potential probe 18 measures the position of the surface potential of the photosensitive layer 3.

The grid electrode type charging section 10 charges the photosensitive layer surface 3a to a positive polarity. The current flowing into the wire W was 180 μ a. The gate voltage was 540V. The first potential probe 12 ("MODEL 1017 AS" manufactured by Monroe Electronics) measures the surface potential of the photosensitive layer 3 after charging. The exposure unit 14 exposes the charged photosensitive layer surface 3 a. The wavelength of light used for exposure was 780 nm. The exposure amount of light used for the exposure was 1.2. mu.J/cm². The negative charging roller 16 negatively charges the photosensitive layer surface 3 a. The inflow current is from-30 muA to-10 muA. The second potential probe 18 ("MODEL 1017 AS" manufactured by Monroe Electronics) measures the surface potential of the photosensitive layer 3 after the negative charging.

The charged potential V can be obtained by measuring the charged potential and the post-transfer potential after the first, second, and third steps₀And post-transfer potential V_t. In the first step, only the grid electrode type charging section 10 is charged while the photoreceptor 1 rotates 1 time (1 rotation), and the photoreceptor 1 rotates 5 rotations. In the second step, after the first step, while the photoreceptor 1 rotates 1 rotation, the grid electrode type charging section 10 charges the photosensitive layer surface 3a and the exposure unit 14 exposes the charged photosensitive layer surface 3a, and the photoreceptor 1 rotates 10 rotations. In the third step, after the second step, while the photoreceptor 1 rotates 1 rotation, the charging of the photosensitive layer surface 3a by the grid electrode type charging section 10, the exposure of the charged photosensitive layer surface 3a by the exposure unit 14, and the negative charging of the exposed photosensitive layer surface 3a by the negative charging roller are performed, and the photoreceptor 1 rotates 5 rotations.

After the photosensitive layer surface 3a is positively charged by the grid electrode type charging section 10, the charged potential after the first to third steps is measured by the first potential probe 12. The current flowing into the wire was 180 μ A. The gate voltage was 540V.

After the photosensitive layer surface 3a is charged by the grid electrode type charging section 10, exposed by the exposure unit 14, and negatively charged by the negative charging roller 16, the post-exposure potential after the first to third steps is measured by the second potential probe 18. The wavelength of light used for exposure was 780 nm. The exposure amount of light used for the exposure was 1.2. mu.J/cm²。

The applied currents (-10. mu.A, -15. mu.A, -20. mu.A, -25. mu.A and-30. mu.A) in the negative charging process were varied, and the charging potential V of each applied current was measured separately₀And post-transfer potential V_t。

[ conductive substrate ]

The conductive substrate 2 contains aluminum or an aluminum alloy. The conductive substrate 2 contains aluminum or an aluminum alloy, and therefore, the movement of charge from the photosensitive layer 3 to the conductive substrate 2 tends to be enhanced. An aluminum alloy is an alloy of aluminum and an element other than aluminum. Elements other than aluminum such as: manganese (Mn), silicon (Si), magnesium (Mg), copper (Cu), iron (Fe), chromium (Cr), titanium (Ti) or zinc (Zn). The aluminum alloy may contain 1 kind of element other than aluminum, or may contain 2 or more kinds of elements. Aluminum alloys such as: Al-Mn based alloys (JIS3000 series), Al-Mg based alloys (JIS5000 series), or Al-Mg-Si based alloys (JIS6000 series).

The surface of the conductive substrate 2 may contain an oxide film of aluminum or an oxide film of an aluminum alloy. The aluminum oxide film or the aluminum alloy oxide film is formed by, for example, subjecting the surface of the conductive substrate 2 to oxidation treatment.

The shape of the conductive substrate 2 can be appropriately selected according to the structure of the image forming apparatus to be used. The conductive substrate 2 has a sheet-like or drum-like shape, for example. The thickness of the conductive substrate 2 may be appropriately selected according to the shape of the conductive substrate 2.

[ photosensitive layer ]

The photosensitive layer 3 contains a charge generator, a hole transporting agent, an electron transporting agent, a binder resin, and an additive. The additive contains carboxylic anhydride. The photosensitive layer 3 may contain additives other than carboxylic anhydride, as required. The following describes a carboxylic anhydride, a charge generator, an electron transport agent, a hole transport agent, a binder resin, and additives (additives other than carboxylic anhydride).

(Carboxylic anhydride)

Examples of the carboxylic anhydride include carboxylic anhydrides represented by general formulae (1), (2), (3), (4) and (5) (hereinafter, these carboxylic anhydrides may be referred to as carboxylic anhydrides (1) to (5), respectively).

[ CHEM 1 ]

In the general formula (1), R¹And R²Each independently represents a C1-C6 alkyl group which may have 1 or several halogen atoms. R¹And R²May be the same or different.

In the general formulae (2), (3), (4) and (5), ring Y₂Ring Y₃Ring Y_4ARing Y_4BRing Y_5AAnd ring Y_5BEach independently represents a monocyclic non-aromatic heterocyclic ring having 5 to 7 ring atoms. The non-aromatic heterocyclic ring contains 2 carbon atoms and 1 oxygen atom of the condensed carboxyl group as ring-forming atoms. The non-aromatic heterocyclic ring may contain 1 or several hetero atoms as ring-constituting atoms in addition to the oxygen atom. Ring Y₂The non-aromatic heterocyclic ring has 1 or several first substituents.

Ring Y₃Ring Y_4ARing Y_4BRing Y_5AAnd ring Y_5BThe non-aromatic heterocyclic ring may have 1 or several second substituents. The first substituent and the second substituent are independent of each other and are a halogen atom or a C6-C14 aryl group. Ring Y_4AAnd ring Y_4BMay be the same or different. Ring Y_5AAnd ring Y_5BMay be the same or different.

Ring Z₃Ring Z₄Ring Z_5AAnd ring Z_5BIs monocyclic or polycyclic, each condensed to ring Y₃Ring Y_4AAnd ring Y_4BRing Y_5AAnd Y_5BAnd is 1 or several C6-C14 aromatic hydrocarbon rings or C3-C14 aromatic heterocyclic rings. Ring Z₃Ring Z₄Ring Z_5AAnd ring Z_5BMay have 1 or several fourth substituents. Wherein, when ring Z₃When it is an aromatic heterocyclic ring, ring Z₃Having a fourth substituent. The fourth substituent represents: C2-C4 alkynyl groups which may have C6-C14 aryl groups, C1-C6 alkyl groups, carboxyl groups, halogen atoms or nitro groups.

X represents: a methylene group which may have 1 or several third substituents, a carbonyl group, a sulfonyl group, a single bond, a divalent group represented by the formula (5-1), or an oxygen atom. The third substituent represents a C1-C6 alkyl group which may have 1 or several halogen atoms. Further, the asterisk in the chemical formula (5-1) indicates the binding site.

[ CHEM 2 ]

In the general formulae (4) and (5), ring Y_4ARing Y_4BRing Y_5AAnd ring Y_5BThe non-aromatic heterocyclic ring represented contains 2 carbon atoms and 1 oxygen atom as ring-constituting atoms. That is, the non-aromatic heterocyclic ring is: a cycloalkyl ring having 5 to 7 ring atoms in which 3 carbon atoms are substituted with 2 carbon atoms and 1 oxygen atom. Monocyclic cycloalkyl rings having 5 or more and 7 or less ring atoms include, for example: a cyclopentane ring, a cyclohexane ring, or a cycloheptane ring.

The 2 carbon atoms and 1 oxygen atom of the non-aromatic heterocyclic ring mean: the condensed carboxyl group has 2 carbon atoms and 1 oxygen atom, and is an atom of a site of condensation in the carboxyl group represented by the chemical formula (5-3). Specifically, in the chemical formula (5-3), carbon atoms and oxygen atoms are shown by dotted circles. The non-aromatic heterocyclic ring may further contain 1 or several hetero atoms (more specifically, nitrogen atom and the like) as ring-constituting atoms in addition to the oxygen atom in the chemical formula (5-3).

[ CHEM 3 ]

Ring Z₄Is and ring Y_4AAnd ring Y_4BCondensed 1 or several C6-C14 aromatic hydrocarbon rings or C3-C14 aromatic heterocyclic rings, preferably 1C 6-C14 aromatic hydrocarbon ring. Ring Y_4AAnd ring Y_4BAnd ring Z₄The site of condensation may be a double bond.

Ring Z_5AAnd ring Z_5BAre each independently of ring Y_5AAnd ring Y_5BCondensed 1 or several C6-C14 aromatic hydrocarbon rings or C3-C14 aromatic heterocyclic rings, preferably 1C 6-C14 aromatic hydrocarbon ring. Ring Y_5AAnd ring Z_5AThe site of condensation may be a double bond. Ring Y_5BAnd ring Z_5BThe site of condensation may be a double bond.

X preferably represents: a methylene group having 2 third substituents, a carbonyl group, a sulfonyl group, a single bond, a divalent group represented by the formula (5-1), or an oxygen atom. The third substituent more preferably represents a C1-C6 alkyl group having 2 halogen atoms, a C1-C3 alkyl group having a plurality of halogen atoms, and still more preferably a methyl group having a plurality of fluorine atoms. In the divalent substituent represented by the chemical formula (5-1), the portion indicated by an asterisk indicates a binding site.

In the formula (4), ring Y is preferred_4AAnd ring Y_4BA monocyclic non-aromatic heterocycle having 5 or 6 ring atoms, ring Z₄Represents a benzene ring or a naphthalene ring.

Carboxylic acid anhydride (4) such as: carboxylic anhydrides represented by chemical formulae (ADD-1), (ADD-2) or (ADD-5) (hereinafter, sometimes referred to as carboxylic anhydrides (ADD-1), (ADD-2) and (ADD-5), respectively).

[ CHEM 4 ]

In the formula (5), ring Y is preferred_5AAnd ring Y_5BA non-aromatic heterocyclic ring having 5 ring atomsZ_5AAnd ring Z_5BRepresents 1 benzene ring, X represents a methylene group or a single bond having 2 third substituents, and the third substituents represent C1-C3 alkyl groups having several fluorine atoms (more specifically, trifluoromethyl group, etc.).

The carboxylic anhydride (5) is, for example, a carboxylic anhydride represented by the general formula (5-2) (hereinafter, may be referred to as carboxylic anhydride (5-2)).

[ CHEM 5 ]

In the general formula (5-2), X⁵Represents a methylene group having 2 third substituents or a single bond. The third substituent represents a C1-C3 alkyl group having several fluorine atoms (more specifically, trifluoromethyl group and the like).

The carboxylic anhydride (5) is, for example, a carboxylic anhydride represented by the chemical formulae (ADD-3) and (ADD-4) (hereinafter, sometimes referred to as carboxylic anhydride (ADD-3) and carboxylic anhydride (ADD-4), respectively).

[ CHEM 6 ]

Of the carboxylic anhydrides (1) to (5), carboxylic anhydrides (4) and (5) are preferable from the viewpoint of further improving the transferability of the toner image. More preferably, in the formula (4), ring Y_4AAnd ring Y_4BA monocyclic non-aromatic heterocycle having 5 or 6 ring atoms, ring Z₄Represents a benzene ring or a naphthalene ring, the carboxylic anhydride represented by the general formula (5) is represented by the general formula (5-2), wherein X is represented by the general formula (5-2)⁵Represents a methylene group or a single bond having 2 third substituents, the third substituents representing C1-C3 alkyl groups having several fluorine atoms.

The content of the carboxylic anhydride is preferably 0.20 parts by mass or more and 7.00 parts by mass or less, and more preferably 0.50 parts by mass or more and 5.00 parts by mass or less, with respect to 100 parts by mass of the binder resin.

(Charge generating agent)

The charge generating agent is not particularly limited as long as it is a charge generating agent for a photoreceptor. Charge generators such as: phthalocyanine pigments, perylene pigments, disazo pigments, dithione-pyrrolopyrrole (dithioketo-pyrropyrole) pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaric acid pigments, trisazo pigments, indigo pigments, azulene pigments, cyanine pigments, powders of inorganic photoconductive materials (more specifically, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, or the like), pyranyl salts, anthanthrone pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, or quinacridone pigments.

Examples of the phthalocyanine pigment include metal-free phthalocyanine and metal phthalocyanine represented by the formula (CGM-1). Examples of the metal phthalocyanine include oxytitanium phthalocyanine represented by the formula (CGM-2) and phthalocyanine in which a metal other than titanium dioxide is coordinated (more specifically, V-type hydroxygallium phthalocyanine and the like). The phthalocyanine pigment may be crystalline or amorphous. 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 can be used.

[ CHEM 7 ]

[ CHEM 8 ]

Examples of metal phthalocyanine-free crystals are: an X-type crystal of metal-free phthalocyanine (hereinafter, sometimes referred to as X-type metal-free phthalocyanine). Crystals of oxytitanium phthalocyanine such as: an alpha-type crystal, a beta-type crystal or a Y-type crystal of oxytitanium phthalocyanine. When the photosensitive layer contains a carboxylic anhydride as an additive, the charge generator is preferably a metal-free phthalocyanine.

The charge generating agent having an absorption wavelength in a desired region may be used alone, or two or more kinds of charge generating agents may be used in combination. Examples of the digital optical image forming apparatus include: a laser printer or a facsimile machine using a light source such as a semiconductor laser. In the digital optical image forming apparatus, the photoreceptor 1 having sensitivity in a wavelength region of 700nm or more is preferably used. Therefore, phthalocyanine pigments are preferable, and metal-free phthalocyanines are more preferable. One kind of charge generating agent may be used alone, or two or more kinds may be used in combination.

In the photoreceptor used in an image forming apparatus using a short-wavelength laser light source, an anthanthrone pigment or a perylene pigment is preferably used as the charge generating agent. The wavelength of the short-wavelength laser light is, for example, in a range of 350nm to 550 nm.

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

(hole transport agent)

Hole transport agents such as triphenylamine derivatives; diamine derivatives (more specifically, N ' -tetraphenylbenzidine derivatives, N ' -tetraphenyl-p-triphenylenediamine derivatives, N ' -tetraphenylphenylenediamine derivatives, di (aminophenylvinyl) benzene derivatives, or N, N ' -tetraphenylphenylenediamine (N, N ' -tetraphenylphenylenediamine) derivatives, etc.); oxadiazole compounds (more specifically, 2, 5-bis (4-methylaminophenyl) -1, 3, 4-oxadiazole and the like); a styrene compound (more specifically, 9- (4-diethylaminostyryl) anthracene, etc.); carbazole-based compounds (more specifically, polyvinylcarbazole and the like); an organic polysilane compound; pyrazolines (more specifically, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, etc.); a hydrazone compound; indole compounds; an oxazole compound; isoxazoles compounds; thiazole compounds; a thiadiazole compound; imidazole compounds; a pyrazole compound; or a triazole compound. These hole-transporting agents may be used alone or in combination of two or more. Among these hole transport agents, compounds represented by the general formula (HTM) are more preferable.

[ CHEM 9 ]

In the general formula (HTM), R¹¹、R¹²、R¹³And R¹⁴Independently of one another, represents C-C6 alkyl or C1-C6 alkoxy. a11, a12, a13 and a14 are independent of each other and each represents an integer of 0 to 5. Wherein a11, a12, a13 and a14 are not all 0. a11 represents an integer of 2 to 5, and R's are several¹¹May be the same or different. a12 represents an integer of 2 to 5, and R's are several¹²May be the same or different. a13 represents an integer of 2 to 5, and R's are several¹³May be the same or different. a14 represents an integer of 2 to 5, and R's are several¹⁴May be the same or different.

In the general formula (HTM), R¹¹、R¹²、R¹³And R¹⁴The C1-C6 alkoxy group is preferably a C1-C3 alkoxy group, and more preferably a methoxy group. al1, a12, a13 and a14 are each independently, preferably represent 0 or 1, more preferably, a11 and a13 represent 1 and a12 and a14 represent 0, or a11 and a13 represent 0 and a12 and a14 represent 1.

The hole-transporting agent represented by the general formula (HTM) is, for example, a compound represented by the chemical formula (HTM-1) (hereinafter, sometimes referred to as a hole-transporting agent (HTM-1)).

[ CHEM 10 ]

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.

From the viewpoint of further improving the transferability of the toner image, the content ratio of the hole transporting agent to the mass of the photosensitive layer is preferably 25% by mass or more, more preferably 30% by mass or more, and still more preferably 30% by mass or more and 50% by mass or less.

(Electron transport agent)

Electron transport agents such as: quinone compounds, imide compounds, hydrazone compounds, malononitrile compounds, thiopyran compounds, trinitrothioxanthone compounds, 3, 4, 5, 7-tetranitro-9-fluorenone compounds, dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2, 4, 8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride or dibromomaleic anhydride. Quinone compounds are exemplified by: a diphenoquinone compound, an azoquinone compound, an anthraquinone compound, a naphthoquinone compound, a nitroanthraquinone compound or a dinitroanthraquinone compound. These electron transport agents may be used alone or in combination of two or more. Among these electron transport agents, a compound represented by the general formula (ETM) is preferable.

[ CHEM 11 ]

In the general formula (ETM), R²¹And R²²Each independently represents a C1-C6 alkyl group or a hydrogen atom. R²³And R²⁴Each independently represents a C1-C6 alkyl group. b23 and b24 each independently represent an integer of 0 to 4. b23 represents an integer of 2 to 4, a plurality of R²³May be the same or different. b24 represents an integer of 2 to 4, a plurality of R²⁴May be the same or different.

In the general formula (ETM), R²¹And R²²Preferably represents a C1-C5 alkyl group, more preferably a1, 1-dimethylpropyl group. b23 and b24 preferably represent 0.

The electron-transporting agent represented by the general formula (ETM) is, for example, a compound represented by the chemical formula (ETM-1) (hereinafter, sometimes referred to as an electron-transporting agent (ETM-1)).

[ CHEM 12 ]

The content of the electron-transporting 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.

(Binder resin)

Examples of binding resins are: a thermoplastic resin, a thermosetting resin, or a photocurable resin. Thermoplastic resins such as: a polyester resin, a polycarbonate resin, a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, a styrene-maleic acid copolymer, a styrene-acrylic acid copolymer, an acrylic acid copolymer, a polyethylene resin, an ethylene-vinyl acetate copolymer, a chlorinated polyethylene resin, a polyvinyl chloride resin, a polypropylene resin, an ionomer, a vinyl chloride-vinyl acetate copolymer, an alkyd resin, a polyamide resin, a polyurethane resin, a polyarylate resin, a polysulfone resin, a diallyl phthalate resin, a ketone resin, a polyvinyl butyral resin, or a polyether resin. Thermosetting resins such as: silicone resins, epoxy resins, phenolic resins, urea-formaldehyde resins, melamine resins or other cross-linking thermosetting resins. The photocurable resin is, for example: epoxy acrylic resin or polyurethane-acrylic copolymer. The resin may be used alone or in combination of two or more.

Among these binding resins, polycarbonate resins are preferred. When the binder resin is a polycarbonate resin, a photosensitive layer having an excellent balance among processability, mechanical strength, optical performance, and abrasion resistance can be easily obtained. Among the polycarbonate resins, a bisphenol Z type polycarbonate resin, a bisphenol CZ type polycarbonate resin, or a bisphenol C type polycarbonate resin is preferable, and a polycarbonate resin represented by chemical formula (Z), (C), or (CZ) is more preferable, from the viewpoint of easily improving the toner image transferability of the photoreceptor. In formulae (Z), (C) and (CZ), the subscripts of the repeat units represent: the mole fraction of moles of recurring units indexed by subscript relative to the total moles of recurring units in the resin.

[ CHEM 13 ]

[ CHEM 14 ]

[ CHEM 15 ]

The viscosity average molecular weight of the binder resin is preferably 40,000 or more, and more preferably 40,000 or more and 52,500 or less. When the viscosity average molecular weight of the binder resin is 40,000 or more, the abrasion resistance of the photoreceptor is easily improved. When the viscosity average molecular weight of the binder resin is 52,500 or less, the binder resin is easily dissolved in the solvent at the time of forming the photosensitive layer 3, and the viscosity of the coating liquid for photosensitive layer does not become too high. Thereby easily forming the photosensitive layer 3.

(additives other than Carboxylic anhydrides (1) to (5))

Additives other than the carboxylic anhydrides (1) to (5) include: a deterioration inhibitor (more specifically, an antioxidant, a radical scavenger, a quencher or an ultraviolet absorber, etc.), a softening agent, a surface modifier, an extender, a thickener, a dispersion stabilizer, a wax, an acceptor, a donor, a surfactant, a plasticizer, a sensitizer or a leveling agent.

(combination of materials)

In the photosensitive layer 3, the carboxylic anhydride is preferably any one of carboxylic anhydrides (ADD-1) to (ADD-5), and the hole-transporting agent is preferably a hole-transporting agent (HTM-1). Among the photosensitive layers 3, preferred are: the carboxylic anhydride is any one of carboxylic anhydrides (ADD-1) to (ADD-5), and the electron-transporting agent is an electron-transporting agent (ETM-1). In the photosensitive layer 3, the carboxylic anhydride is preferably any one of carboxylic anhydrides (ADD-1) to (ADD-5), and the binder resin is preferably a polycarbonate resin represented by the chemical formula (Z). In the photosensitive layer 3, the carboxylic anhydride is preferably any one of carboxylic anhydrides (ADD-1) to (ADD-5), and the charge generator is preferably X-type metal-free phthalocyanine. In the photosensitive layer 3, it is more preferable that the carboxylic anhydride is any one of carboxylic anhydrides (ADD-1) to (ADD-5), the charge generator is X-type metal-free phthalocyanine, the hole transport agent is a hole transport agent (HTM-1), the electron transport agent is an electron transport agent (ETM-1), and the binder resin is a polycarbonate resin represented by chemical formula (Z).

[ intermediate layer ]

The intermediate layer 4 (particularly, an undercoat layer) is located, for example, between the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 contains, for example, inorganic particles and a resin (intermediate layer resin). It is considered that the presence of the intermediate layer 4 allows smooth flow of current generated when the photoreceptor 1 is exposed, while maintaining an insulating state to such an extent that generation of electric leakage can be suppressed, and thus can suppress an increase in electric resistance.

Inorganic particles such as: particles of a metal (more specifically, aluminum, iron, copper, or the like), particles of a metal oxide (more specifically, titanium oxide, aluminum oxide, zirconium oxide, tin oxide, zinc oxide, or the like), or particles of a non-metal oxide (more specifically, silicon dioxide, or the like). These inorganic particles may be used alone or in combination of two or more.

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

The intermediate layer 4 may also contain additives. The additive of the intermediate layer 4 is the same as that of the photosensitive layer 3. [ method for producing photoreceptor ]

A method for manufacturing the photoreceptor 1 will be described with reference to fig. 1. The method for manufacturing the photoreceptor 1 includes a photosensitive layer forming step. The photosensitive layer forming step will be described below.

(photosensitive layer Forming step)

In the photosensitive layer forming step, a coating liquid for photosensitive layer (hereinafter, sometimes referred to as a coating liquid) is applied to the conductive substrate 2 to form a coating film. At least a part of the solvent contained in the coating film is removed to form the photosensitive layer 3. The photosensitive layer forming step includes, for example: a coating liquid preparation step, a coating step and a drying step. The coating liquid preparation step, the coating step, and the drying step will be described below.

(coating liquid preparation Process)

In the coating liquid preparation step, a coating liquid is prepared. The coating liquid contains at least: a charge generator, a hole transporting agent, an electron transporting agent, a binder resin, a carboxylic anhydride as an additive, and a solvent. The coating liquid may contain other additives as necessary. The coating liquid can be prepared by, for example, dissolving or dispersing a charge generator, a hole transporting agent, an electron transporting agent, a binder resin, a carboxylic anhydride as an additive, and optional components in a solvent.

The solvent contained in the coating liquid is not particularly limited as long as each component contained in the coating liquid can be dissolved or dispersed. Solvents such as: alcohols (more specifically, methanol, ethanol, isopropanol, butanol, or the like), aliphatic hydrocarbons (more specifically, N-hexane, octane, cyclohexane, or the like), aromatic hydrocarbons (more specifically, benzene, toluene, xylene, or the like), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, or the like), ethers (more specifically, dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or the like), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, or the like), esters (more specifically, ethyl acetate, methyl acetate, or the like), dimethyl formaldehyde, N-Dimethylformamide (DMF), or dimethyl sulfoxide. These solvents may be used alone, or two or more of them may be used in combination. Among these solvents, non-halogenated solvents are preferable.

The coating liquid is prepared by mixing the respective components and dissolving or dispersing in a solvent. Mixing, dissolving or dispersing can be carried out, for example, using a bead mill, roll mill, ball mill, attritor, paint shaker or ultrasonic disperser.

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

(coating Process)

In the coating step, the coating liquid is applied to the conductive substrate 2 to form a coating film. The method for applying the coating liquid is not particularly limited as long as the coating liquid can be uniformly applied to the conductive substrate 2, for example. Examples of the coating method include: dip coating, spray coating, spin coating or bar coating.

The method of applying the coating liquid is preferably a dip coating method in terms of easily adjusting the thickness of the photosensitive layer 3 to a desired value. When the dip coating method is used in the coating step, the conductive substrate 2 is immersed in the coating liquid in the coating step. Next, the impregnated conductive substrate 2 is pulled up from the coating liquid. Thereby, the coating liquid is applied to the conductive substrate 2.

(drying Process)

In the drying step, at least a part of the solvent contained in the coating film is removed. The method for removing at least a part of the solvent contained in the coating film is not particularly limited as long as the solvent in the coating liquid can be evaporated. Examples of the removal method include: heating, reducing pressure or heating and reducing pressure. More specifically, for example, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a reduced-pressure dryer. The heat treatment conditions are, for example, a temperature of 40 ℃ to 150 ℃ and a time of 3 minutes to 120 minutes.

The method for manufacturing the photoreceptor may further include one or both of the step of forming the intermediate layer and the step of forming the protective layer, as necessary. The step of forming the intermediate layer and the step of forming the protective layer can be realized by appropriately selecting a known method.

< second embodiment: image Forming apparatus

An embodiment of an image forming apparatus according to a second embodiment will be described with reference to fig. 3. Fig. 3 is an example of an image forming apparatus according to a second embodiment. The image forming apparatus 90 according to the second embodiment includes an image forming unit 40. The image forming unit 40 includes: an image carrier 30, a charging section 42, an exposure section 44, a developing section 46, and a transfer section 48. The image carrier 30 is the photoreceptor according to the first embodiment. The charging section 42 charges the surface of the image carrier 30. The charging polarity of the charging section 42 is positive. The phrase "the charging polarity of the charging section 42 is positive" means that the charging section 42 charges the surface of the image carrier 30 with positive polarity. The exposure section 44 exposes the surface of the charged image carrier 30, and forms an electrostatic latent image on the surface of the image carrier 30. The developing section 46 develops the electrostatic latent image into a toner image. The transfer section 48 transfers the toner image from the surface of the image carrier 30 to the recording medium M. The outline of the image forming apparatus 90 according to the second embodiment is described above.

The image forming apparatus 90 according to the second embodiment can form an image having excellent toner image transferability. The reason for this is considered as follows: as described in the first embodiment, the photoreceptor according to the first embodiment is excellent in toner image transferability. Therefore, the image forming apparatus 90 according to the second embodiment includes the photoreceptor according to the first embodiment as the image carrier 30, and thus has excellent toner image transferability. Hereinafter, an image failure due to a decrease in transferability of a toner image will be described as an example.

Hereinafter, an image in which an image failure has occurred will be described with reference to fig. 3 and 4. Fig. 4 shows an image with a defective image due to a decrease in transferability of the toner image on the photoreceptor. Image 100 has region 102, region 104, and region 106. Each of the regions 102, 104, and 106 corresponds to 1 turn of the image carrier 30. The image 108 of the region 102 includes a rectangular solid image (image density 100%). Both the region 104 and the region 106 are images (image density 0%) with a blank design. Along the direction a (conveyance direction a) in which the recording medium is conveyed, first, the image 108 of the area 102 is formed, then, the blank image of the area 104 is formed, and finally, the blank image of the area 106 is formed. The blank image of the region 104 corresponds to the image of the lower 1 turn of the image carrier 30. That is, the blank image of the region 104 is an image corresponding to the image carrier 30 of the 2 nd turn with reference to the 1 st turn (hereinafter, sometimes referred to as a reference turn) of the image carrier 30 on which the image 108 is formed. The blank image of the region 106 corresponds to the image of the lower 1 turn of the image carrier 30, and corresponds to the image of the image carrier 30 of the 3 rd turn from the reference turn of the image carrier 30 on which the image 108 is formed.

The blank image of the area 110 of the area 104 is an image corresponding to the image 108 in the 2 nd turn from the reference turn of the image carrier 30. The blank image of the area 112 of the area 106 is an image corresponding to the image 108 in the 3 rd turn from the reference turn of the image carrier 30. In this case, an image reflecting the image 108 is formed in the region 110 and/or the region 112, and an image failure occurs. Thus, image defects due to a decrease in the toner image transferability of the image carrier 30 occur periodically on a circumferential length basis of the image carrier 30. Images reflecting the image 108 are easily formed on both end portions of the recording medium. This is presumably because the pressing force is strong to both end portions of the recording medium. Here, the both end portions of the recording medium are, for example, both end portions in the vertical direction b in the area 110 (the area 110L and the area 110R) of the recording medium, and also both end portions in the vertical direction b in the area 112 (the area 112L and the area 112R). The vertical direction b is a direction perpendicular to the conveying direction a.

Hereinafter, referring back to fig. 3, each part of the image forming apparatus 90 according to the second embodiment will be described in detail. The image forming apparatus 90 is not particularly limited as long as it is an electrophotographic image forming apparatus. The image forming apparatus 90 may be a monochrome image forming apparatus or a color image forming apparatus, for example. When image forming apparatus 90 is a color image forming apparatus, image forming apparatus 90 employs, for example, a tandem system. Hereinafter, the tandem image forming apparatus 90 will be described as an example.

The image forming apparatus 90 employs a direct transfer system. In general, in an image forming apparatus employing a direct transfer method, the transferability of a toner image is liable to be lowered, and an image failure due to the lowered transferability is liable to occur. However, the image forming apparatus 90 according to the second embodiment includes the photoreceptor according to the first embodiment as the image carrier 30. The photoreceptor according to the first embodiment is excellent in toner image transferability. Therefore, it is considered that, when the photoreceptor according to the first embodiment is provided as the image carrier 30, even if the image forming apparatus 90 employs the direct transfer method, it is possible to suppress image defects caused by a decrease in toner image transferability.

The image forming apparatus 90 further includes a conveyor belt 50 and a fixing unit 52.

The image forming unit 40 forms an image. The image forming unit 40 may be constituted by image forming units 40a, 40b, 40c, and 40d of respective colors. The image forming units 40a to 40d sequentially superimpose toner images of several colors (for example, four colors of black, cyan, magenta, and yellow) on the recording medium M on the conveying belt 50. When image forming apparatus 90 is a monochrome image forming apparatus, image forming apparatus 90 includes image forming unit 40a, and image forming units 40b to 40d are omitted.

The image forming unit 40 may further include a cleaning unit (not shown). The cleaning section cleans the blade, for example. The image carrier 30 is disposed at the center of the image forming unit 40. The image carrier 30 is provided to be rotatable in an arrow direction (counterclockwise direction). Around the image carrier 30, a charging section 42, an exposure section 44, a developing section 46, and a transfer section 48 are provided in this order from the upstream side in the rotation direction of the image carrier 30 with reference to the charging section 42. The image forming unit 40 may further include a power removing unit (not shown).

The charging section 42 is a charging roller. The charging roller is brought into contact with the surface of the image carrier 30 to charge the surface of the image carrier 30. The voltage applied by the charging section 42 is not particularly limited. The voltage applied by the charging unit 42 is, for example, a dc voltage, an ac voltage, or a superimposed voltage (a voltage in which an ac voltage is superimposed on a dc voltage), and is more preferably a dc voltage. The dc voltage has the following advantages compared to the ac voltage or the superimposed voltage. When only the dc voltage is applied to the charging section 42, the voltage applied to the image carrier 30 is constant, and therefore, the surface of the image carrier 30 is easily charged uniformly to a constant potential. Further, when only the dc voltage is applied to the charging section 42, the amount of abrasion of the photosensitive layer tends to decrease. Thus, a preferable image can be formed.

The exposure section 44 exposes the surface of the charged image carrier 30. Thereby, an electrostatic latent image is formed on the surface of the image carrier 30. An electrostatic latent image is formed based on image data input to the image forming apparatus 90.

The developing section 46 develops the electrostatic latent image into a toner image. The developing unit 46 can clean the surface of the image carrier 30. That is, the image forming apparatus 90 according to the second embodiment may employ a non-blade cleaner system. In an image forming apparatus employing the blade cleaner-less system, generally, the transferability of a toner image is liable to be lowered, and the lowered transferability is liable to cause an image failure. However, the image forming apparatus 90 according to the second embodiment includes the photoreceptor according to the first embodiment as the image carrier 30. Therefore, even if the blade-less cleaner system is adopted in the image forming apparatus 90 according to the second embodiment, it is possible to suppress an image failure due to a reduction in toner image transferability.

In order for the developing section 46 to efficiently clean the surface of the image carrier 30, the following conditions (1) and (2) are preferably satisfied.

Condition (1): a contact development method is adopted and a difference in rotation speed is provided between the image carrier 30 and the developing roller.

Condition (2): the difference between the surface potential of the image carrier 30 and the potential of the developing bias satisfies the following equations (2-1) and (2-2).

0(V) < potential of developing bias (V) < surface potential of unexposed area of image bearing body 30 (V) … … equation (2-1)

Potential of developing bias (V) > surface potential of exposed region of image bearing body 30 (V) > 0(V) … … equation (2-2)

In the equation (2-1), the surface potential (V) of the unexposed region of the image bearing member 30 is the surface potential of the unexposed region of the image bearing member 30 that is not exposed by the exposed portion 44. In the equation (2-2), the surface potential (V) of the exposure region of the image carrier 30 is the surface potential of the exposure region of the image carrier 30 exposed by the exposure portion 44. After the transfer section 48 transfers the toner image from the image bearing member 30 to the recording medium M, and before the charging section 42 charges the surface of the image bearing member 30 for the next cycle, the surface potential of the unexposed area and the surface potential of the exposed area of the image bearing member 30 are measured.

In the contact development method shown in the condition (1), when a difference in rotation speed is provided between the image carrier 30 and the developing roller, the surface of the image carrier 30 is in contact with the developing roller, and the residual component on the surface of the image carrier 30 is removed by friction with the developing roller. The image forming apparatus 90 according to the second embodiment may employ a contact development system. In the image forming apparatus 90 employing the contact development method, the developing portion 46 develops the electrostatic latent image into a toner image while contacting the surface of the image carrier 30.

The rotation speed of the image bearing member 30 is preferably 120 mm/sec to 350 mm/sec. The rotation speed of the developing roller is preferably 133 mm/sec to 700 mm/sec. Further, the rotation speed V of the image carrier 30_PAnd the rotational speed V of the developing roller_DThe ratio (c) preferably satisfies the formula (1-1). When the ratio is other than 1, it means that a difference in rotation speed is provided between the image carrier 30 and the developing roller.

0.5≤V_P/V_DLess than or equal to 0.8 … … formula (1-1)

In the condition (2), a case where the charging polarity of the toner is positive charging and the developing system is a reversal developing system will be described as an example. When a difference is provided between the potential of the developing bias and the surface potential of the image carrier 30 as shown in the condition (2), in the unexposed area, the electrostatic repulsive force acting between the residual toner (hereinafter, sometimes referred to as residual toner) and the unexposed area of the image carrier 30 is larger than the electrostatic repulsive force acting between the residual toner and the developing roller because the surface potential (charging potential) of the image carrier 30 and the potential of the developing bias satisfy the equation (2-1). Therefore, the residual toner moves from the surface of the image carrier 30 to the developing roller and is collected. The toner is difficult to adhere to the unexposed area of the image carrier 30.

When a difference is provided between the potential of the developing bias and the surface potential of the image carrier 30 as shown in the condition (2), the electrostatic repulsive force acting between the residual toner and the exposure region of the image carrier 30 is smaller than the electrostatic repulsive force acting between the toner and the developing roller in the exposure region because the surface potential of the image carrier 30 (post-exposure potential) and the potential of the developing bias satisfy the equation (2-2). Therefore, the residual toner on the surface of the image carrier 30 remains on the surface of the image carrier 30. The toner adheres to the exposed area of the image carrier 30.

The potential of the developing bias is, for example, +250V or more and +400V or less. The charged potential of the image carrier 30 is, for example, +450V or more and +900V or less. The post-exposure potential of the image carrier 30 is, for example, +50V or more and +200V or less. The difference between the potential of the developing bias and the charged potential of the image carrier 30 is, for example, +100V or more and +700V or less. The difference between the potential of the developing bias and the post-exposure potential of the image carrier 30 is, for example, +150V or more and +300V or less. Here, the potential difference represents an absolute value of the difference. The conditions for providing such a potential difference are, for example, "potential of developing bias + 330V", "charged potential of image carrier 30 + 600V", and "post-exposure potential of image carrier 30 + 100V".

The transfer section 48 is a transfer roller. The transfer roller transfers the toner image developed by the developing portion 46 from the surface of the image carrier 30 to the recording medium M. When the toner image is transferred from the image carrier 30 to the recording medium M, the image carrier 30 comes into contact with the recording medium M.

The transport belt 50 transports the recording medium M so that the recording medium M passes between the image carrier 30 and the transfer unit 48. The conveyor belt 50 is an endless belt. The conveyor belt 50 is provided to be rotatable in the arrow direction (clockwise direction).

When the toner image is transferred to the recording medium M by the transfer section 48, the fixing section 52 fixes the unfixed toner image by heating and/or pressing. Thereby, an image is formed on the recording medium M. The fixing unit 52 is, for example, a heat roller and/or a pressure roller.

< third embodiment: treatment Cartridge >

The third embodiment relates to a process cartridge. A process cartridge according to a third embodiment includes the photoreceptor according to the first embodiment. Next, a process cartridge according to a third embodiment will be described with reference to fig. 3.

The process cartridge is provided with an image carrier 30. The image carrier 30 may be unitized. The process cartridge includes at least 1 selected from the group consisting of a charging section 42, an exposure section 44, a developing section 46, and a transfer section 48 in addition to the image carrier 30. The process cartridges correspond to the respective image forming units 40a to 40d, for example. The process cartridge may further include a cleaning unit or a static eliminator (not shown). The process cartridge is designed to be detachable from the image forming apparatus 90. Therefore, when the process cartridge is easy to handle and the toner image transferability of the image carrier 30 is deteriorated, the process cartridge including the image carrier 30 can be easily and quickly replaced.

[ examples ] A method for producing a compound

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the scope of the examples.

[ Material of photoreceptor ]

As a material for forming the photosensitive layer of the photoreceptor, the following charge generating agent, hole transporting agent, electron transporting agent and binder resin are prepared.

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

The hole transporting agent (HTM-1) and the electron transporting agent (ETM-1) described in the first embodiment are prepared.

The preliminary additives (ADD-6) and (ADD-7) and the carboxylic anhydrides (ADD-1) to (ADD-5) described in the first embodiment. The additives (ADD-6) and (ADD-7) are represented by chemical formulas (ADD-6) and (ADD-7), respectively.

[ CHEM 16 ]

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

[ production of photoreceptor ]

The photoreceptors (A-1) to (A-9) and the photoreceptors (B-1) to (B-4) were manufactured using the materials prepared for forming the photosensitive layer of the photoreceptor.

(production of photoreceptor (A-1))

First, a conductive substrate is prepared. The conductive substrate was an aluminum conductive substrate having a diameter of 160mm, a length of 365mm and a thickness of 2 mm.

A coating liquid was prepared. Adding into a container: 2.0 parts by mass of a compound (CGM-1X) as a charge generating agent, 45 parts by mass of a hole transporting agent (HTM-1), 30 parts by mass of an electron transporting agent (ETM-1), 100 parts by mass of a polycarbonate resin (Za) as a binder resin, 0.1 part by mass of a carboxylic acid anhydride (ADD-1) as an additive, and 800 parts by mass of tetrahydrofuran as a solvent. The contents of the container were mixed for 50 hours by a ball mill and dispersed to obtain a coating liquid. The content ratio of the hole-transporting agent to the mass of the solid portion (compound (CGM-1X), hole-transporting agent (HTM-1), electron-transporting agent (ETM-1), polycarbonate resin (Za) and carboxylic acid anhydride (ADD-1)) was 25% by mass.

Next, the coating liquid is coated on the conductive substrate by a dip coating method, and a coating film is formed on the conductive substrate. Specifically, the conductive substrate is immersed in the coating liquid. Next, the impregnated conductive substrate is pulled out from the coating liquid. Thereby, the coating liquid is applied to the conductive substrate to form a coating film.

Next, the conductive substrate on which the coating film was formed was dried at 100 ℃ for 40 minutes by hot air. Thereby, the solvent (tetrahydrofuran) contained in the coating film was removed. As a result, a single photosensitive layer is formed on the conductive substrate. Thus, photoreceptor (A-1) was obtained.

(production of photoreceptors (A-2) to (A-9) and photoreceptors (B-1) to (B-4))

Photoreceptors (A-2) to (A-9) and photoreceptors (B-1) to (B-4) were produced by the same method as for producing photoreceptor (A-1) except for the following modifications.

In the production process of the photoreceptor (A-1), the kind of the additive used for adjusting the coating liquid was changed from the carboxylic anhydride (ADD-1) to the one shown in Table 4. The content ratio of the hole transport agent to the mass of the photosensitive layer, 25 mass%, was changed to the content ratio shown in table 4. The change value of the relative dielectric constant was changed to the change value of the relative dielectric constant shown in table 4.

(value of change in relative permittivity of photosensitive layer)

The change value of the relative dielectric constant of the photosensitive layer is calculated by the method described in the first embodiment. Specifically, with the method and conditions described in the first embodiment, the charge amount Q of the surface of the photosensitive layer of each negative current is measured by changing the negative current. Table 1 shows the charge Q of the surface of the photosensitive layer.

[ TABLE 1 ]

The charged potential V was measured by the method and conditions described in the first embodiment₀And post-transfer potential V_tCalculating these potential differences (V)₀-V_t). Table 2 shows the potential difference (V)₀-V_t)。

[ TABLE 2 ]

The film thickness of the photosensitive layer was measured by the method and conditions described in the first embodiment. Table 3 shows the film thickness of the photosensitive layer.

[ TABLE 3 ]

Based on the obtained electric quantity Q and potential difference V, using equation (2)₀-V_t) To calculate the relative dielectric constant ε_r. Table 4 shows the relative dielectric constant ε_r。

(evaluation of transferability of toner image on photoreceptor)

The photoreceptor was mounted on an evaluation apparatus. The evaluation equipment used a printing apparatus ("FS-1300D" manufactured by Kyowa office information systems Co., Ltd., dry electrophotographic printing apparatus using a semiconductor laser). The evaluation equipment includes a charging roller as a charging unit. The charging roller is applied with a direct-current voltage. The evaluation apparatus includes a transfer unit (transfer roller) of a direct transfer system. The evaluation apparatus includes a developing unit of a contact development system. The evaluation equipment did not have a cleaning blade. The developing part of the evaluation apparatus can clean the surface of the object carrier. The paper used for the evaluation of transferability was "Jing porcelain office information System Brand paper VM-A4(A4 size)" sold by Jing porcelain office information System, Inc. The toner used for evaluation of transferability was "TK-131" manufactured by Kyowa office information systems. The measurement of the transferability evaluation was performed under a high-temperature high-humidity (temperature 32.5 ℃ C. and relative humidity 80% RH) environment.

An evaluation image for evaluation was formed on a sheet of paper using an evaluation device equipped with a photoreceptor and a toner. The evaluation image will be specifically described below with reference to fig. 5. The image forming conditions were set to a linear velocity of 165 mm/sec. The current applied to the photoreceptor by the transfer roller was set to-25 μ A.

Then, the presence or absence of an image corresponding to the image 208 in the region 210 and the region 212 is confirmed by visual inspection of the obtained image. Based on the observation results obtained by visual observation, the toner image transferability of the photoreceptor was evaluated according to the following evaluation criteria. The evaluation A (very good) and the evaluation B (good) were passed. The column entitled "transferability" in table 4 represents the evaluation results.

The evaluation image will be described with reference to fig. 5. Fig. 5 shows an evaluation image. The evaluation image 200 includes a region 202, a region 204, and a region 206. The region 202 corresponds to 1 turn of the image carrier. The image 208 of the region 202 is composed of only a solid image (image density 100%). The solid image is rectangular in shape. The regions 204 and 206 are regions corresponding to 1 turn of the image carrier, and both include a blank image (image density 0%). The image 208 of the area 202 is first formed in the conveying direction a, and then blank images of the area 204 and the area 206 are formed. The blank image of the area 204 is an image formed at the 2 nd circle with reference to the circle (reference circle) where the image 208 is formed. Region 210 is a region corresponding to image 208 in region 204. The blank image of the area 206 is an image formed at the 3 rd circle from the reference circle where the image 108 is formed. Region 212 is a region corresponding to image 208 in region 206.

(evaluation criteria for transferability)

Evaluation a (very good): no image corresponding to image 208 is confirmed in area 210 and area 212.

Evaluation B (good): a few images corresponding to the image 208 are confirmed at both ends of the region 210 in the vertical direction b; no image corresponding to image 208 is confirmed in region 212.

Evaluation C (poor): images corresponding to the image 208 are clearly confirmed at both ends of the area 210 in the vertical direction b; no image corresponding to image 208 is confirmed in region 212.

Evaluation D (very poor): the image corresponding to the image 208 is clearly recognized at both ends of the area 210 and the area 212 in the vertical direction b.

As shown in table 4, the photosensitive layers of the photoreceptors (a-1) to (a-9) were single-layer photosensitive layers, and included a charge generator, a hole transporting agent, an electron transporting agent, and an additive. The additive is carboxylic anhydride represented by chemical formulas (ADD-1) to (ADD-5). The photosensitive layer has a change value of relative dielectric constant of 1.00 or more.

As shown in Table 4, the results of evaluation of the toner image transferability of the photoreceptors (A-1) to (A-9) were evaluation A (excellent) or evaluation B (excellent).

As shown in Table 4, in the photoreceptors (B-1) to (B-4), the change in the relative dielectric constant of the photosensitive layer was less than 1.00. In the photoreceptor (B-1), the photosensitive layer does not contain a carboxylic anhydride as an additive.

As shown in Table 4, all of the photoreceptors (B-1) to (B-4) were evaluated for their toner image transferability as evaluation C (poor).

As described above, the photoreceptors (A-1) to (A-9) are superior in toner image transferability to the photoreceptors (B-1) to (B-4).

Claims (6)

1. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer,

the conductive substrate contains aluminum or an aluminum alloy,

the photosensitive layer is a single layer of a photosensitive layer,

the photosensitive layer contains a charge generator, a hole transporting agent, an electron transporting agent, a binder resin and an additive,

the additive comprises a carboxylic acid anhydride and a carboxylic acid anhydride,

the carboxylic anhydride is represented by at least 1 of chemical formulas (ADD-1), (ADD-3) and (ADD-4),

the change value of the relative dielectric constant is more than 3.68,

the change value of the relative dielectric constant is obtained by charging the photosensitive layer with a wavelength of 780nm and an exposure amount of 1.2 muJ/cm²The charged photosensitive layer is exposed to light, a plurality of relative dielectric constants are calculated when a current of-30 muA to-10 muA flows into the exposed region, and the difference between the maximum value and the minimum value of the relative dielectric constants, that is, the change value of the relative dielectric constants is obtained,

the content ratio of the hole-transporting agent is 35 to 50 mass% based on the mass of the photosensitive layer,

2. the electrophotographic photoreceptor according to claim 1,

the hole transporting agent comprises a compound represented by the general formula (HTM),

in the general formula (HTM) below,

R¹¹、R¹²、R¹³and R¹⁴Independently of one another, represents C1-C6 alkyl or C1-C6 alkoxy,

a11, a12, a13 and a14 are independent of each other and each represents an integer of 0 to 5 inclusive,

a11, a12, a13 and a14 are not all 0,

a11 represents an integer of 2 to 5, and R's are several¹¹Which may be the same or different from each other,

a12 represents an integer of 2 to 5, and R's are several¹²Which may be the same or different from each other,

a13 represents an integer of 2 to 5, and R's are several¹³Which may be the same or different from each other,

a14 represents an integer of 2 to 5, and R's are several¹⁴May be the same or different.

3. The electrophotographic photoreceptor according to claim 1 or 2,

the electron transport agent comprises a compound represented by the general formula (ETM),

in the general formula (ETM),

R²¹and R²²Each independently represents a C1-C6 alkyl group or a hydrogen atom,

R²³and R²⁴Independently of one another, represents a C1-C6 alkyl group,

b23 and b24 each independently represents an integer of 0 to 4,

b23 represents an integer of 2 to 4, a plurality of R²³Which may be the same or different from each other,

b24 represents an integer of 2 to 4, a plurality of R²⁴May be the same or different.

4. A kind of processing box is disclosed, which comprises a box body,

the electrophotographic photoreceptor according to claim 1 or 2.

5. An image forming apparatus includes:

an image bearing body;

a charging unit for charging a surface of the image carrier;

an exposure section that exposes the surface of the charged image carrier to form an electrostatic latent image;

a developing section that develops the electrostatic latent image into a toner image; and

a transfer section for transferring the toner image from the surface of the image bearing member to a recording medium,

the image bearing member is the electrophotographic photoreceptor according to claim 1 or 2,

the charging polarity of the charging portion is positive.

6. The image forming apparatus according to claim 5,

the charging section is a charging roller.

Images