JP5664342B2 - Electrophotographic photosensitive member, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, an electrophotographic process cartridge, and an image forming apparatus used for a copying machine, a printer, and the like. More specifically, the present invention relates to an electrophotographic photoreceptor excellent in surface mechanical properties and electrical characteristics, an electrophotographic process cartridge using the same, and an image forming apparatus.

The electrophotographic technology is widely used as a copying machine, a printer, and a printing machine because a high-quality image can be obtained immediately.
For the electrophotographic photoreceptor (hereinafter referred to as “photoreceptor” as appropriate) which is the core of the electrophotographic technology, an organic photoconductive material having advantages such as non-polluting, easy film formation and easy production was used. Photoconductors are widely used.

  In recent years, due to the demand for higher image quality, the diameter of toner has been reduced, and in particular, the shape of a chemical toner is often close to a sphere, so that when the toner remaining on the photoreceptor is cleaned with a blade, the toner slips through. This is likely to occur, and as a result, there is a high possibility of image defects such as dirt. For this reason, measures are often taken to bring the cleaning blade into contact with the photosensitive member with a strong pressure to prevent the toner from slipping through, and the photosensitive member is likely to be worn.

  On the other hand, as the electrophotographic apparatus is reduced in size and speeded up, the diameter of the photoconductor is reduced, and further improvement in responsiveness (quick reduction of the exposed portion potential) is required.

Japanese Patent Laid-Open No. 11-212289 Japanese Patent Laid-Open No. 06-289629 JP 2000-258930 A JP 2000-019765 A JP 2000-284508 A JP 2001-356500 A Japanese Patent No. 3788723 Japanese Patent No. 3144117 Japanese Patent Application Laid-Open No. 08-220783 Japanese Patent Laid-Open No. 06-075389 Japanese Patent Laid-Open No. 09-204053

  If the contact pressure of the cleaning blade to the photoconductor increases, the blade will repeatedly stick and slide with the outermost surface of the photoconductor, causing chatter due to the so-called stick-slip phenomenon, resulting in an increased risk of abnormal noise. In addition, toner may slip through during slipping, resulting in poor cleaning and a possibility of streak-like image defects. In addition, the pressure of the blade not only causes the photoconductor to be easily worn, but also causes a so-called filming phenomenon in which the toner component is fixed on the surface of the photoconductor and is difficult to remove, resulting in persistent image defects. The risk of becoming is also high. Furthermore, image defects due to the occurrence of scratches in the circumferential direction due to rotation in a state where the toner is strongly pressed against the photosensitive member are likely to occur.

  As a means for improving the surface mechanical properties of the photoreceptor in this way, polyester resin, especially polyarylate resin, which is wholly aromatic polyester resin, has a high elastic deformation rate, and therefore means that can meet the demands for severe mechanical property improvement. Has been put to practical use. However, polyester resins are generally inferior in electrical properties as compared with polycarbonate resins, and even if they are superior in mechanical properties, they are often insufficient in electrical properties. For this reason, measures to mix polyester resin and polycarbonate resin have also been proposed (Patent Documents 1 to 7), but since they are intermediate properties in terms of performance, there is a difficulty in negating the advantages of both. there were.

  On the other hand, various studies have been made on the polycarbonate resin represented by the following general formula (1) and its copolymer, which have high solubility and translucency and a high elastic deformation rate. (Patent Documents 8 to 11) However, the problem of the present invention has not been solved.

(In the general formula (1), Z forms a cyclic saturated aliphatic alkyl group having 5 to 8 carbon atoms including carbon atoms to be bonded, and the cyclic saturated aliphatic alkyl group has 1 to 3 methyl groups. Group as a substituent.)

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have included a specific polycarbonate resin and a polyester resin in the outermost surface layer of the photoconductor, so that both mechanical properties such as wear resistance and electrical characteristics can be obtained. In response to demands, we found that it is possible to demonstrate synergistic effects while taking advantage of both resins, and to suppress the generation of abnormal noise, poor cleaning, and filming, and excellent layer adhesion. The invention has been completed.

The gist of the present invention resides in the following <1> to <5>.
<1>
An electrophotographic photosensitive member characterized in that the outermost surface layer contains at least a polycarbonate resin having a copolymer component represented by the following general formulas (1) and (2) and a polyester resin.

(In the general formula (1), Z forms a cyclic saturated aliphatic alkyl group having 5 to 8 carbon atoms including carbon atoms to be bonded, and the cyclic saturated aliphatic alkyl group has 1 to 3 methyl groups. Group as a substituent.)

(In general formula (2), A ^{1 to} A ⁴ each independently represents a hydrogen atom or a methyl group)
<2>
The electrophotographic photosensitive member according to <1>, wherein the polycarbonate resin is represented by the following structural formula (3).

(In general formula (3), m and n represent a molar ratio, and m: n = 90: 10 to 10:90) <3>
The electrophotographic photosensitive member according to <1> or <2>, wherein the polyester resin is represented by the following general formula (4).

(In the formula (4), Ar ^{1 to} Ar ⁴ each independently represent an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula (5). Or a group represented by the following formula (6): R ¹ and R ^{2 in} formula (5) each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² And R ³ in the formula (6) is an alkylene group, an arylene group, or a group represented by the following formula (7), and in the formula (7) R ⁴ and R ⁵ each independently represents an alkylene group, Ar ⁵ represents an arylene group, k represents an integer of 0 or more, and Y represents a single bond, an oxygen atom, a sulfur atom, or the following formula ( 8) a group represented by the formula (8), ^{R 6} and ^{R 7} each independently represent a hydrogen atom, an alkyl group, alkoxy Represents shea group, or an aryl group, it may be bonded and the R ⁶ and R ⁷ form a ring.)

<4>
A process cartridge comprising the electrophotographic photosensitive member according to <1> to <3>, at least a charging unit, and a cleaning unit.
<5>
An image forming apparatus that forms an image using the electrophotographic photosensitive member according to <1> to <3>, the charging step for charging the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member An exposure process for performing exposure to form an electrostatic latent image; a development process for developing the electrostatic latent image with toner; a transfer process for transferring the toner to a transfer target; and a cleaning process. , Image forming apparatus.

  According to the present invention, it is possible to obtain an electrophotographic photosensitive member that can meet the demands of both mechanical properties such as wear resistance and electrical characteristics, and an electrophotographic photosensitive member cartridge and an image forming apparatus using the same. .

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. It is the graph which showed the load curve with respect to indentation depth.

Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can change arbitrarily and can implement.
First, the binder resin used for the electrophotographic photoreceptor of the present invention will be described.
<Polycarbonate resin>
In the photosensitive layer of the electrophotographic photoreceptor of the present invention, a polycarbonate resin having both of the structural units represented by the following general formulas (1) and (2) as a copolymerization component and a polyester resin described later are used as the outermost layer. contains.

  In the general formula (1), Z forms a cyclic saturated aliphatic alkyl group having 5 to 8 carbon atoms including carbon atoms to be bonded, and the cyclic saturated aliphatic alkyl group has 1 to 3 methyl groups. As a substituent. By introducing a methyl group, the structural flexibility of the cycloalkyl group is suppressed, and the rigidity as a resin is increased. As an example, the homopolymer of the following (1) -6 has a high Tg of 245 ° C., but the homopolymer having no methyl group substitution (commonly called bisphenol-Z-polycarbonate) has a Tg of 180 ° C. Further, by introducing a methyl group asymmetrically, there is an advantage that the solubility is further increased and problems such as gelation of the coating solution can be suppressed. Preferred examples of the general formula (1) are shown below.

Among these, (1) -5 and (1) -6 are preferable, and (1) -6 is most preferable from the viewpoint of mechanical properties and ease of production of the resin. In the structure represented by the general formula (1), structural tautomerism (conversion between boat shape and chair shape) of the cyclohexyl unit is suppressed by methyl group substitution, and rigidity is increased as described above.
Further, in the general formula (2) represent respectively A ¹ to A ⁴ independently represent a hydrogen atom or a methyl group.

  Preferred examples of general formula (2) are shown below.

  Since the homopolymer represented by the general formula (1) has a very high Tg as described above, the homopolymer is not preferable from the viewpoint of compatibility with a charge transport material, adhesion to a substrate, and the like for use in a photoreceptor. On the other hand, the homopolymer of the general formula (2) has a relatively low Tg, for example, (2) -1 is about 150 ° C. Therefore, it is possible to adjust to an appropriate Tg by copolymerization of the general formula (1) and the general formula (2). Among the above, (2) -1 and (2) -4 are preferable from the viewpoint of mechanical properties, and (2) -1 is most preferable.

Moreover, 90: 10-10: 90 is preferable and, as for the copolymerization ratio of General formula (2) and General formula (1), when the ratio of General formula (1) increases too much, a glass transition point (Tg) will become high. In addition, since the solubility is also lowered, the general formula (2): general formula (1) = 90: 10 to 50:50 is more preferable.
Moreover, the case where the copolymer resin which has a structural unit represented by General formula (1) and General formula (2) is represented by following General formula (3) is especially preferable.

In the general formula (3), m and n represent a molar ratio, usually m: n = 90: 10 to 10:90, preferably 90:10 to 50:50, most preferably 85:15 to 60. : 40.
Moreover, as a preferable molecular weight, it is 30,000 or more and 200,000 or less by weight average molecular weight (polystyrene conversion), More preferably, it is 40,000 or more and 100,000 or less. The viscosity average molecular weight is preferably 10,000 or more, more preferably 15,000 or more, and the upper limit is preferably 70,000 or less, more preferably 50,000 or less. If the value of the viscosity average molecular weight is too small, the mechanical strength may be insufficient, and if it is too large, the viscosity of the coating solution for forming the photosensitive layer may be too high, resulting in a decrease in productivity. In addition, a viscosity average molecular weight can be measured by the method as described in an Example using an Ubbelohde type capillary viscometer etc., for example.

<Polyester resin>
The polycarbonate resin is used as a mixture with a polyester resin. As the polyester resin, any polyester resin that is thermoplastic and soluble in an organic solvent can be used.
The polyester resin is obtained by polycondensing a polyhydric alcohol component and a polyvalent carboxylic acid component such as a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid ester as a raw material monomer. As the polyhydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4
-Hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4
-Hydroxyphenyl) propane alkylene (carbon number 2-3) oxide (average addition mole number 1-10) adduct, ethylene glycol, propylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, Hydrogenated bisphenol A, sorbitol, or alkylene thereof (2 to 2 carbon atoms)
3) Oxide (average added mole number: 1 to 10) adduct, aromatic bisphenol and the like can be mentioned, and those containing one or more of these are preferable.

The polyvalent carboxylic acid component includes dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and maleic acid, carbon numbers such as dodecenyl succinic acid and octyl succinic acid.
Succinic acid, trimellitic acid, pyromellitic acid, anhydrides of these acids and alkyl (1 to 3 carbon atoms) esters of these acids substituted with -20 alkyl groups or C2-C20 alkenyl groups The thing containing 1 or more types of these is preferable.

  Among these polyester resins, a wholly aromatic polyester resin (polyarylate resin) represented by the following general formula (4) is preferable.

(In the formula (4), Ar ^{1 to} Ar ⁴ each independently represent an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula (5). Or a group represented by the following formula (6): R ¹ and R ^{2 in} formula (5) each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² And R ³ in the formula (6) is an alkylene group, an arylene group, or a group represented by the following formula (7), and in the formula (7) R ⁴ and R ⁵ each independently represents an alkylene group, Ar ⁵ represents an arylene group, k represents an integer of 0 or more, and Y represents a single bond, an oxygen atom, a sulfur atom, or the following formula ( 8) a group represented by the formula (8), ^{R 6} and ^{R 7} each independently represent a hydrogen atom, an alkyl group, alkoxy Represents shea group, or an aryl group, it may be bonded and the R ⁶ and R ⁷ form a ring.)

In the above formula (4), the number of carbon atoms contained in the arylene group of Ar ^{1 to} Ar ⁴ is usually 6 or more, and the upper limit thereof is usually 20 or less, preferably 10 or less, more preferably 6. is there. If the number of carbon atoms is too large, the production cost increases and the electrical characteristics may also deteriorate.
Specific examples of the arylene group of Ar ^{1 to} Ar ⁴ include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, naphthylene group, anthrylene group, phenanthrylene group, and the like. Of these, a 1,4-phenylene group is preferred from the viewpoint of electrical characteristics. An arylene group may be used individually by 1 type, and may be used 2 or more types by arbitrary ratios and combinations.

Specific examples of the substituents for Ar ^{1 to} Ar ⁴ include an alkyl group, an aryl group, a halogen group, and an alkoxy group. Among them, considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the alkyl group is preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and is preferably an aryl group. Is preferably a phenyl group or a naphthyl group, a halogen group is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and an alkoxy group is preferably a methoxy group, an ethoxy group, a propoxy group or a butoxy group.

In addition, when a substituent is an alkyl group, carbon number of the alkyl group is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 2 or less.
More specifically, Ar ³ and Ar ⁴ each independently preferably has a substituent number of 0 or more and 2 or less, more preferably has a substituent from the viewpoint of adhesion, and among these, substitution from the viewpoint of wear resistance. It is particularly preferable that the number of groups is one. Moreover, as a substituent, an alkyl group is preferable and a methyl group is particularly preferable.

From the above viewpoint, at least one of Ar ³ and Ar ⁴ is preferably an arylene group having a substituent.
On the other hand, Ar ¹ and Ar ² each independently preferably have 0 or more and 2 or less substituents, and more preferably have no substituents from the viewpoint of wear resistance.
In the above formula (4), X represents a single bond, an oxygen atom, a sulfur atom, a group represented by the above formula (5), or a group represented by the above formula (6). R ¹ and R ^{2 in} Formula (5) each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² are bonded to form a ring such as a cycloalkylidene group. It may be. R ³ in the formula (6) is an alkylene group, an arylene group, or a group represented by the above formula (7), and R ⁴ and R ⁵ in the formula (7) are each independently an alkylene group. Ar ⁵ represents an arylene group.

In Formula (4), preferable X includes an oxygen atom, a sulfur atom, a structure represented by Formula (5), or a divalent organic residue having a structure represented by Formula (6).
Examples of the alkyl group of R ¹ and R ² in the formula (5) include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. In addition, examples of the cycloalkylidene group formed by combining R ¹ and R ² in Formula (5) include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptylidene group. Furthermore, examples of the alkylene group represented by R ³ in formula (6) include a methylene group, an ethylene group, and a propylene group. Examples of the arylene group represented by R ³ in formula (6) include a phenylene group and a terphenylene group.

Among these, X is preferably an oxygen atom. At that time, k is preferably 1.
In the above formula (4), Y is a single bond, an oxygen atom, a sulfur atom, or a group represented by the above formula (8).
R ⁶ and R ^{7 in} Formula (8) each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or a cycloalkylidene group formed by combining R ⁶ and R ⁷ . Considering the mechanical properties as the binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, R ⁶ and R ⁷ in the formula (8) are preferably phenyl groups and naphthyl groups as aryl groups, As an alkoxy group, a methoxy group, an ethoxy group, and a butoxy group are preferable. Moreover, as an alkyl group, a C1-C10 alkyl group is preferable, More preferably, it is C1-C8, Most preferably, it is C1-2. Considering the simplicity of production of the divalent hydroxyaryl component used for producing the polyester resin, Y is a single bond, —O—, —S—, —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ — and cyclohexylene are preferable, —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ — and cyclohexylene are particularly preferable, and —CH ₂ is particularly preferable. _{2 -, - CH (CH 3} ) - is.

In the electrophotographic photoreceptor used in the present invention, the polyester resin (4) is preferably a polyester resin having a repeating structure represented by the following general formula (9) when k = 1. In the following general formula (9), Ar ^{6 to} Ar ⁹ each independently represent an arylene group which may have a substituent, and R ⁸ represents a hydrogen atom or an alkyl group.

In the general formula (9), Ar ^{6 to} Ar ⁹ correspond to the Ar ^{1 to} Ar ⁴ , respectively, and particularly preferably a phenylene group which may have a substituent. Moreover, as a preferable substituent, it is a hydrogen atom or an alkyl group, Most preferably, it is a methyl group. Furthermore, in the general formula (9), Ar ⁸ and Ar ⁹ are phenylene groups having a methyl group, and Ar ⁶ and Ar ⁷ are particularly preferably phenylene groups having no substituent. R ⁸ represents a hydrogen atom or an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably a methyl group.

<Dicarboxylic acid residue>
The dicarboxylic acid component which is a dicarboxylic acid residue in the polyester resin is represented by the following general formula (10).

Ar ¹ , Ar ² , X, and k in the general formula (10) are as described above in the general formula (4). As the dicarboxylic acid residue contained in the formula (10), the following general formula [I] The structure represented by-[VI] can be illustrated. Here, k is an integer of 0 or more, but an integer of 0 to 5 is preferable from the viewpoint of electrical characteristics and scratch resistance, and more preferably 0 or 1.

  In the structure represented by the general formula (10), when k is 1, a structure represented by the following general formula (11) in which X is an oxygen atom is preferable.

Specific examples of the preferred dicarboxylic acid residue represented by the general formula (11) include diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,3′-dicarboxylic acid residue, diphenyl ether-2,4 ′. -Dicarboxylic acid residue, diphenyl ether-3,3'-dicarboxylic acid residue, diphenyl ether-3,4'-dicarboxylic acid residue, diphenyl ether-4,4'-dicarboxylic acid residue and the like. Among these, considering the simplicity of production of the dicarboxylic acid component, diphenyl ether-2,2′-dicarboxylic acid residue, diphenyl ether-2,4′-dicarboxylic acid residue, diphenyl ether-4,4′-dicarboxylic acid Residues are more preferred, and diphenyl ether-4,4′-dicarboxylic acid residues are particularly preferred.

Specific examples of the dicarboxylic acid residue represented by the general formula (10) and k = 0 include phthalic acid residue, isophthalic acid residue, terephthalic acid residue, toluene-2,5-dicarboxylic acid residue P-xylene-2,5-dicarboxylic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,3-dicarboxylic acid residue, naphthalene-2,6-dicarboxylic acid residue, biphenyl-2 , 2′-dicarboxylic acid residue, biphenyl-4,4′-dicarboxylic acid residue, preferably phthalic acid residue, isophthalic acid residue, terephthalic acid residue, naphthalene-1,4-dicarboxylic acid A residue, naphthalene-2,6-dicarboxylic acid residue, biphenyl-2,2′-dicarboxylic acid residue, biphenyl-4,4′-dicarboxylic acid residue, particularly preferably an isophthalic acid residue, terephthalic acid acid It is also possible to use a combination of a plurality of these dicarboxylic acid residues. A preferred specific example of the polyester resin in which the dicarboxylic acid residue is represented by the general formula (10) and k = 0 includes the following formula (12). The ratio of isophthalic acid residue to terephthalic acid residue is usually 50:50, but can be arbitrarily changed. In that case, the higher the ratio of terephthalic acid residues, the better from the viewpoint of electrical characteristics.

  The polyester resin may be a resin that contains another dicarboxylic acid component and includes the general formula (10) in a part of the structure. Specific examples of other dicarboxylic acid residues include adipic acid residues, suberic acid residues, sebacic acid residues, pyridine-2,3-dicarboxylic acid residues, pyridine-2,4-dicarboxylic acid residues, pyridine -2,5-dicarboxylic acid residue, pyridine-2,6-dicarboxylic acid residue, pyridine-3,4-dicarboxylic acid residue, pyridine-3,5-dicarboxylic acid residue, preferably, These are adipic acid residues and sebacic acid residues, and a plurality of these dicarboxylic acid residues can be used in combination.

  In addition, when it has the dicarboxylic acid residue (10) which comprises the polyester resin used for this invention, and the other dicarboxylic acid residue mentioned above, the dicarboxylic acid residue (10) which comprises the polyester resin used for this invention However, the number of repeating units is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. Most preferably, the dicarboxylic acid residue (10) constituting the present invention is 100% as the number of repeating units.

The viscosity average molecular weight of the polyester resin used in the present invention is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 10,000 or more, more preferably 20,000 or more, and the upper limit is preferably 70,000 or less, more preferably 50,000 or less is desirable. If the value of the viscosity average molecular weight is too small, the mechanical strength of the polyester resin may be insufficient, and if it is too large, the viscosity of the coating solution for forming the photosensitive layer may be too high and the productivity may decrease. is there. In addition, a viscosity average molecular weight can be measured by the method as described in an Example using an Ubbelohde type capillary viscometer etc., for example.

<Mixing of polycarbonate resin and polyester resin>
The mixing ratio (weight ratio) of the polycarbonate resin and the polyester resin can be arbitrarily set according to the purpose, but is usually polycarbonate resin: polyester resin = 5: 95 to 95: 5, and 20: from the viewpoint of improving wear. 80 to 80:20 is preferable, and 50:50 to 80:20 is more preferable from the viewpoint of further improving the electrical characteristics.

When the polycarbonate resin and the polyester resin are mixed, the wear amount as a photoreceptor is improved more than expected. That is, the amount of wear is significantly less than the simple average of the amount of wear in the case of a single resin. This mechanism is not necessarily clear, but is considered as follows.
In the general formula (1), by adding a substituent to the cycloalkyl group, the rigidity is increased as described above, and the structural transformation is suppressed. As a result, the optimum packing of the polymer does not sufficiently progress in the coating / drying process during the production of the photoreceptor, the free volume increases, and the entanglement of the polymer is not sufficient. By mixing the polyester resin here, it is considered that such a free volume is appropriately filled, the entanglement of the polymers at the molecular level is sufficiently advanced, and the wearability is also improved. Also, the high elastic deformation rate of the polyester resin is not greatly reduced by mixing.

The polycarbonate resin having the copolymer component represented by the above general formulas (1) and (2) and the polyester resin of the present invention are the layers that become the outermost surface of an electrophotographic photosensitive member having a photosensitive layer on a conductive support. However, when a protective layer is provided on the photosensitive layer as described in detail below, it is contained in the protective layer.
Next, the electrophotographic photoreceptor of the present invention will be described including other components.

[I. Electrophotographic photoreceptor]
The photoreceptor of the present invention comprises an outermost surface layer containing the specific polycarbonate resin and a polyester resin. The photoreceptor of the present invention is usually provided on a conductive support (also referred to as “conductive substrate”).
[I-1. Conductive support]
As the conductive support, a known material disclosed in Japanese Patent Application Laid-Open No. 2007-293319, such as aluminum or an aluminum alloy, can be used. Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after providing an anodic oxide film as disclosed by Unexamined-Japanese-Patent No. 2007-293319.

[I-2. Undercoat layer]
An undercoat layer may be provided between the conductive support and the photosensitive layer in order to improve adhesion and blocking properties. As the undercoat layer, known examples disclosed in JP-A-2007-293319 can be used.
[I-3. Photosensitive layer]
The photosensitive layer is formed on the above-mentioned conductive support (or on the undercoat layer when the above-described undercoat layer is provided). As the type of the photosensitive layer, a charge generation material and a charge transport material are present in the same layer and have a single layer structure in which they are dispersed in a binder resin (hereinafter referred to as “single layer type photosensitive layer” as appropriate). , A functionally separated type layered structure composed of two or more layers, including a charge generation layer in which a charge generation material is dispersed in a binder resin, and a charge transport layer in which a charge transport material is dispersed in a binder resin ( Hereinafter, it is referred to as “laminated photosensitive layer” as appropriate, but any form may be used.

In addition, as the laminated photosensitive layer, a charge-generating layer and a charge transport layer are laminated in this order from the conductive support side, and conversely, a charge transport layer and a charge generation layer are formed from the conductive support side. There are reverse laminated photosensitive layers provided in order, and any of them can be adopted, but a forward laminated photosensitive layer that can exhibit the most balanced photoconductivity is preferable.
The polycarbonate resin and the polyester resin of the present invention are contained in a layer which becomes the “outermost surface” of the photosensitive layer regardless of the type of the photosensitive layer.
When forming the charge transport layer of the function-separated type photoreceptor having the charge generation layer and the charge transport layer, a binder resin is used to ensure film strength.

In the case of the charge transport layer of the functional separation type photoreceptor, a coating solution obtained by dissolving or dispersing the charge transport material and the binder resin in a solvent, and in the case of the single layer type photoreceptor, the charge generation material and the charge transport material. And a coating solution obtained by dissolving or dispersing the binder resin in a solvent and applying and drying.
<Functional separation type photosensitive layer>
<Charge transport layer>
<Binder resin>
When the electrophotographic photosensitive member of the present invention is a sequentially laminated type photosensitive member, the above-described polycarbonate resin and polyester resin are contained as a binder resin for the charge transport layer serving as the outermost surface layer. The binder resin may be mixed with other resins as long as the effects of the present invention are not impaired. Examples of the other resins include butadiene resins, styrene resins, vinyl acetate resins, vinyl chloride resins, and acrylate esters. Polymers and copolymers of vinyl compounds such as resins, methacrylic ester resins, vinyl alcohol resins, ethyl vinyl ethers, polyvinyl butyral resins, polyvinyl formal resins, partially modified polyvinyl acetals, polyamide resins, polyurethane resins, cellulose ester resins, phenoxy resins , Silicon resin, silicon-alkyd resin, poly-N-vinylcarbazole resin and the like. These binder resins can be used by crosslinking with an appropriate curing agent by heat, light or the like, and may be modified with a silicon reagent or the like. In that case, it is preferable that the ratio of the mixture of the polycarbonate resin of this invention and a polyester resin is 50 weight% or more.

<Charge transport material>
In the electrophotographic photoreceptor of the present invention, known examples as disclosed in JP-A-2007-293319 can be used as a charge transport material.
The amount of the charge transport material contained in the present invention is arbitrary as long as the effects of the present invention are not significantly impaired. However, if the amount is too small, the charge transport is disadvantageous and the electrical characteristics are deteriorated. Therefore, the amount is usually 30 parts by weight or more, preferably 40 parts by weight or more with respect to 100 parts by weight of the binder resin in the photosensitive layer. And the glass point transfer point (Tg) is too low, and the wear resistance may be deteriorated. Therefore, it is usually 200 parts by weight or less, preferably 150 parts by weight or less.

<Charge generation layer>
The charge generation layer of the laminated photosensitive layer (function-separated type photosensitive layer) contains a charge generation material and usually contains a binder resin and other components used as necessary. Such a charge generation layer is prepared by, for example, preparing a coating solution by dissolving or dispersing fine particles of a charge generation material and a binder resin in a solvent or a dispersion medium. It can be obtained by coating and drying on the top (on the undercoat layer when an undercoat layer is provided) and on the charge transport layer in the case of a reverse laminated type photosensitive layer. When the charge generation layer is the outermost surface layer in the reverse laminated photosensitive layer, the layer contains a polycarbonate resin having a copolymerization component represented by the above general formulas (1) and (2) and a polyester resin.

<Charge generation material>
As an example of the charge generation material, a known material disclosed in Japanese Patent Application Laid-Open No. 2007-293319 can be used. Of these materials, metal-containing phthalocyanines containing a metal at the center of the phthalocyanine ring are preferable. Among metal-containing phthalocyanines, A-type (β-type), B-type (α-type), and D-type (Y-type) oxytitanium. More preferred are phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, G-type μ-oxo-gallium phthalocyanine dimer, A-type (β-type), B-type (α-type), D-type (Y-type) More preferred is oxytitanium phthalocyanine.

In particular, it is preferable that oxytitanium phthalocyanine has a clear diffraction peak mainly at a Bragg angle (2θ ± 0.2 °) of 27.2 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray.
In addition, the oxytitanium dirocyanine has a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 9.0 ° to 9.7 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray. ,preferable.

When an azo pigment is used as the charge generation material, various known bisazo pigments and trisazo pigments are preferably used.
As the pigment used as the charge generation material, a preferable material may be determined depending on the exposure wavelength used. When the exposure wavelength is in the short wavelength region of about 380 nm to 500 nm, the above azo pigment is preferably used. On the other hand, when near-infrared light of about 630 to 780 nm is used, a phthalocyanine pigment having high sensitivity also in that region and a part of azo pigments are preferably used. On the other hand, even when environmental characteristics such as humidity dependency are required to be small, the Bragg angle (2θ ± 0.2 °) is set to 9.0 ° to 9.7 ° in the powder X-ray diffraction spectrum by CuKα characteristic X-ray. Since oxytitanium phthalocyanine having a clear diffraction peak is highly dependent on humidity, the above azo pigment is preferably used.

It is desirable that the particle size of the charge generating material used is sufficiently small. Specifically, it is usually 1 μm or less, preferably 0.5 μm or less.
Furthermore, if the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity may not be obtained. If the amount is too large, the chargeability may decrease, the sensitivity may decrease, the smoothness may decrease due to aggregation, etc. There are harmful effects. Therefore, the amount of the charge generating material in the charge generating layer of the multilayer photosensitive layer is usually 20% by weight or more, preferably 40% by weight or more, and usually 90% by weight or less, preferably 70% by weight or less.

<Binder resin>
The binder resin used for the charge generation layer constituting the multilayer photosensitive layer is not particularly limited, and for example, a known material disclosed in JP-A-2007-293319 can be used.
Specifically, the charge generation layer is prepared by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent to prepare a coating solution, which is then formed on a conductive support (when an undercoat layer is provided). Is formed by coating (on the undercoat layer).

<Single layer type photosensitive layer>
The single-layer type photosensitive layer is formed by using both the polycarbonate resin and the polyester resin described above as the binder resin in the same manner as the charge transport layer of the function-separated type photoreceptor in addition to the charge generation material and the charge transport material. In addition, the binder resin may be mixed with other resins as long as the effect of the present invention is not impaired in the same manner as the charge transport layer. A single-layer type photosensitive layer is prepared by dissolving or dispersing a charge generating substance, a charge transporting substance, and the binder resin in a solvent to form a coating solution, and on a conductive support (if an undercoat layer is provided, on the undercoat layer). ) And dried.

The types of the charge transport material and the binder resin and the use ratios thereof are the same as those described for the charge transport layer of the multilayer photoreceptor. A charge generation material is further dispersed in a charge transport medium comprising these charge transport materials and a binder resin.
As the charge generation material, the same materials as those described for the charge generation layer of the multilayer photoreceptor can be used. However, in the case of a photosensitive layer of a single layer type photoreceptor, it is necessary to sufficiently reduce the particle size of the charge generating material. Specifically, the range is usually 1 μm or less, preferably 0.5 μm or less.

If the amount of the charge generating material dispersed in the single-layer type photosensitive layer is too small, sufficient sensitivity cannot be obtained, but if it is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. The total amount of the layer-type photosensitive layer is usually 0.5% by mass or more, preferably 1% by mass or more, and usually 50% by mass or less, preferably 20% by mass or less.
In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is set as the range of 10 mass parts or less.

Next, other components of the laminated / single layer type photosensitive layer will be described.
<Other components>
Furthermore, the photosensitive layer may contain various additives. These additives are used to improve film formability, flexibility, mechanical strength, and the like. For example, plasticizers, short-wavelength light absorbers such as ultraviolet rays, antioxidants, and residual potential are suppressed. For example, residual potential inhibitors for improving dispersion stability, leveling agents for improving coating properties (for example, silicone oil, fluorine-based oil, etc.), surfactants and the like. In addition, 1 type may be used for an additive and it may use 2 or more types together by arbitrary combinations and a ratio.

<Film thickness>
In the photoreceptor of the present invention, the thickness of the photosensitive layer is not particularly limited as long as the effects of the present invention are not significantly impaired. In the case of a single-layer photoreceptor, it is usually 10 μm or more, preferably 15 μm or more. Usually, it is 50 μm or less, preferably 45 μm or less. In the case of a multilayer photoreceptor, the charge generation layer is preferably 0.1 μm or more and 1 μm or less, more preferably 0.2 μm or more and 0.8 μm or less, and the charge transport layer is usually 5 μm or more, preferably 10 μm or more, Usually, it is 40 μm or less, preferably 35 μm or less. The charge transport layer may be formed not only from a single layer but also from two or more different layers.

<Universal hardness and elastic deformation rate>
In order to suppress abnormal noise caused by friction with the cleaning blade and to suppress the occurrence of scratches on the surface, it is preferable that the surface hardness of the photosensitive layer is high. From the viewpoint of preventing defective cleaning of the toner, the elasticity of the photosensitive layer is preferred. It is preferable that the deformation rate is high. From the viewpoint of suppressing filming, it is preferable that both the hardness and the elastic deformation rate are high. The hardness and elastic deformation rate depend on both the charge transporting material and the binder resin, and are also affected by the compatibility thereof, so that it is necessary to design the materials to be in a suitable range. The preferred surface hardness of the photosensitive layer is, as a universal hardness value, the lower limit is usually 175 N / mm ² or more, preferably 180 N / mm ² or more, more preferably 190 N / mm ² or more, and the upper limit is usually 290 N / mm ^2. mm ² or less, preferably 270 N / mm ² or less. The range of the preferred elastic deformation rate of the photosensitive layer is usually 38% or more as the lower limit, preferably 40% or more, more preferably 42% or more, from the viewpoint of preventing poor cleaning, and the upper limit is usually 60% or less. , Preferably 55% or less.

The elastic deformation rate and the universal hardness in the present invention are values measured under an environment of a temperature of 25 ° C. and a relative humidity of 50% using a microhardness meter FISCHERSCOPE H100C (or an equivalent machine, HM2000) manufactured by Fischer. For the measurement, a Vickers square pyramid diamond indenter having a facing angle of 136 ° is used. The measurement conditions are set as follows, the load applied to the indenter and the indentation depth under the load are continuously read, and profiles as shown in FIG. 2 plotted on the Y axis and the X axis are obtained.
・ Measurement conditions Maximum indentation load 5mN
Load required time 10 seconds Unloading required time 10 seconds The above elastic deformation rate is a value defined by the following formula, and the work performed by the film due to elasticity at the time of unloading with respect to the total work required for indentation. It is a ratio.

Elastic deformation rate (%) = (We / Wt) × 100
In the above formula, the total work Wt (nJ) indicates the area surrounded by A-B-D-A in FIG. 2, and the elastic deformation work We (nJ) is the area surrounded by C-B-D-C. Indicates. As the elastic deformation rate is larger, the deformation with respect to the load is less likely to remain, and when the elastic deformation rate is 100, it means that no deformation remains.

Moreover, said universal hardness is a value when it pushes in to indentation load 5mN, and is a value defined by the following formula | equation from the indentation depth at that time.
Universal hardness (N / mm ² ) = Test load (N) / Vickers indenter surface area under test load (mm ² )
[I-4. Other layers]
A protective layer may be provided as the outermost surface layer on the photosensitive layer. In this case, the protective layer contains at least the mixed binder resin of the polycarbonate resin and the polyester resin. Moreover, you may add an additive suitably to the said protective layer. Examples thereof include resin particles such as fluorine resin, silicone resin, and cross-linked polystyrene resin, and inorganic particles such as alumina particles and silica particles. Further, when the thickness of the protective layer is greater than 1 μm, the physical properties of the protective layer dominate the surface mechanical properties more than the influence of the lower layer. Therefore, the material used for the lower photosensitive layer is within the range specified in the present invention. Any known material may be used regardless of the above.

[I-5. Formation method of each layer]
There are no limitations on the method of forming each layer such as the undercoat layer, the photosensitive layer, and the protective layer. For example, a known method such as applying a coating solution obtained by dissolving or dispersing a material contained in a layer to be formed in a solvent directly onto a conductive support directly or via another layer is applied. it can. After coating, the photosensitive layer is formed by removing the solvent by drying.

  In this case, the coating method is not limited and may be arbitrary. For example, a dip coating method, a spray coating method, a nozzle coating method, a bar coating method, a roll coating method, a blade coating method, or the like can be used. Among these, the dip coating method is preferable because of its high productivity. Note that these coating methods may be performed by only one method, or may be performed by combining two or more methods.

[I-6. Photoconductor charging type]
The photoreceptor of the present invention is used for image forming applications by being used in an image forming apparatus described later. The laminated photoreceptor of the present invention is used with negative charge, and the single-layer photoreceptor is used with positive charge.
[I-7. Photoconductor exposure wavelength]
When forming an image, the photosensitive member of the present invention is exposed to writing light from an exposure unit to form an electrostatic latent image. The writing light used at this time is arbitrary as long as an electrostatic latent image can be formed, but monochromatic light having an exposure wavelength of usually 380 nm or more, particularly 400 nm or more and usually 850 nm or less is used. In particular, when monochromatic light of 480 nm or less is used, the photosensitive member can be exposed with light having a smaller spot size, and a high-quality image having high resolution and high gradation can be formed. When it is desired to obtain the light, exposure with monochromatic light of 480 nm or less is preferable.

[II. Image forming apparatus, process cartridge]
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (an image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

As shown in FIG. 1, the image forming apparatus includes an electrophotographic photoreceptor 1, a charging device (charging means) 2, an exposure device (exposure means; image exposure means) 3, and a developing device (developing means) 4. Furthermore, a transfer device (transfer means) 5, a cleaning unit 6, and a fixing device (fixing means) 7 are provided as necessary.
The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5 and a cleaning unit 6 are arranged along the outer peripheral surface of the electrophotographic photosensitive member 1.

The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but other corona charging devices such as corotron and scorotron, and contact-type charging devices such as charging brushes are often used.
The electrophotographic photosensitive member 1, the charging device 2, and the cleaning unit 6 are often used as cartridges (electrophotographic photosensitive member cartridge of the present invention, hereinafter referred to as “process cartridge” as appropriate) from the main body of the image forming apparatus. Designed to be removable and replaceable. For example, when the electrophotographic photosensitive member 1, the charging device 2, and the cleaning unit 6 are deteriorated, the process cartridge can be removed from the image forming apparatus main body, and another new process cartridge can be mounted on the image forming apparatus main body. It has become. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a process cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, the cleaning unit 6, and the toner may be used.

  The type of exposure apparatus 3 is not particularly limited as long as it can form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member 1 by performing exposure (image exposure) on the electrophotographic photosensitive member 1. Absent. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, and LEDs (light emitting diodes). Further, exposure may be performed by a photoreceptor internal exposure method. The light used for exposure is arbitrary, but is generally preferably monochromatic light. For example, monochromatic light having a wavelength (exposure wavelength) of 700 nm to 850 nm, monochromatic light having a wavelength of 600 nm to 700 nm, slightly shorter wavelength, and having a wavelength of 300 nm to 500 nm. Exposure may be performed with short-wave monochromatic light or the like.

The type of the developing device 4 is not particularly limited as long as it can develop the exposed electrostatic latent image on the electrophotographic photosensitive member 1 into a visible image. Specific examples include cascade development,
Any apparatus such as a dry development system such as a one-component conductive toner development or a two-component magnetic brush development, or a wet development system can be used. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicone resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.
The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. However, the developing roller 44 and the electrophotographic photosensitive member 1 may not be in contact with each other but may be close to each other. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed of a resin blade such as silicone resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such metal blade with resin. The regulating member 45 normally abuts on the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 0.05 to 5 N / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

The agitator 42 is provided as necessary, and is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers a toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium, transfer target). Transfer to P.

The cleaning unit 6 collects residual toner adhering to the photoreceptor 1 by scraping it off with a cleaning blade and storing it in a recovery container. The cleaning blade includes an elastic rubber member and a support member, and an edge member may be further provided on the photosensitive member contact portion of the elastic rubber member as necessary. Generally, polyurethane is used for these cleaning blade members. This is because polyurethane is an elastic body, has good wear resistance, has sufficient mechanical strength without adding a reinforcing agent, and is non-staining. However, it is known that the physical properties of polyurethane have temperature dependence. The temperature dependence appears particularly in the resilience and is a problem in cleaning. That is, when the impact resilience is lowered at a low temperature, a cleaning failure is caused. Therefore, it is desired to provide a highly functional cleaning blade that has sufficiently stable rebound resilience even when the environment changes. In particular, since the temperature inside the device is likely to rise with the recent downsizing of the device, such a reduction in the temperature dependence of the resilience is increasingly required. In order to obtain such a resilience polyurethane, the elastic rubber member or edge member is made of a polyester polyol obtained by reacting adipic acid and a diol component, or a polyurethane made from a caprolactone polyester polyol as a raw material. However, it is preferable from the viewpoint of improving the cleaning efficiency. The properties of polyurethane are: 100% permanent elongation is 3% or less, rebound resilience at 25 ° C is 20% or less, and the difference between the maximum and minimum rebound resilience between 10 ° C and 50 ° C is 30% or less. It is preferable that

Further, from the viewpoint of improving the cleaning property, it is preferable that the cleaning blade counter-contacts the photoconductor.
The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. Each of the upper and lower fixing members 71 and 72 includes a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, and a fixing sheet. A member can be used. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.
The type of the fixing device is not particularly limited, and a fixing device of any type such as heat roller fixing, flash fixing, oven fixing, pressure fixing, etc. can be provided including those used here.

  In the electrophotographic apparatus configured as described above, a charging step for charging the photosensitive member, an exposure step for exposing the charged photosensitive member to form an electrostatic latent image, and developing the electrostatic latent image with toner. An image is recorded by performing a developing process and a transferring process for transferring the toner to the transfer target. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential by the charging device 2 (charging process). At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.

Subsequently, the photosensitive member is exposed to form an electrostatic latent image (exposure process). That is, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface.
Then, development of the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1 is performed by the developing device 4 (developing process). The developing device 4 thins the toner T supplied by the supply roller 43 by a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and positive polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1. When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1.

The toner image is transferred to the recording paper P by the transfer device 5 (transfer process). Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning unit 6.
After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.

In addition to the above-described configuration, the image forming apparatus may have a configuration capable of performing, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

  The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.

  Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. However, the following examples are given in order to explain the present invention in detail, and the present invention is not limited to the examples shown below without departing from the gist thereof, and can be arbitrarily modified and implemented. can do. In addition, the description of “parts” in the following production examples, examples, and comparative examples indicates “parts by weight” unless otherwise specified. The polycarbonate resins used in the examples (PC1 to PC3 below) are commercially available from Bayer under the trade name APEC, and were used as received without further purification.

[Comparative Example 1]
<Manufacture of coating liquid>
The undercoat layer forming coating solution was prepared as follows. Rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were used in a Henschel mixer The surface-treated titanium oxide obtained by mixing was dispersed by a ball mill in a mixed solvent having a methanol / 1-propanol weight ratio of 7/3 to obtain a surface-treated titanium oxide dispersed slurry. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula (B ) / Hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula ( The compound represented by E)] has a composition molar ratio of 60% / 15% / 5% / 15% / 5% and is agitated and mixed with pellets of copolymerized polyamide to dissolve the polyamide pellets. Then, by ultrasonic dispersion treatment, the weight ratio of methanol / 1-propanol / toluene is 7/1/2, and the surface-treated titanium oxide / copolymerized polyamide. In a weight ratio of 3/1, to prepare a coating liquid for forming an undercoat layer having a solid concentration of 18.0%.

The charge generation layer forming coating solution was prepared as follows.
First, as a charge generation material, 20 parts of Y-type (also called D-type) oxytitanium phthalocyanine, which has a strong diffraction peak at 27.3 ° in the Bragg angle (2θ ± 0.2) in X-ray diffraction by CuKα rays, 280 parts of 2-dimethoxyethane was mixed and pulverized with a sand grind mill for 1 hour for atomization dispersion treatment. Subsequently, 10 parts of polyvinyl butyral (trade name “Denka Butyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl. A binder liquid obtained by dissolving in 85 parts of 2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution for forming a charge generation layer.
The charge transport layer forming coating solution was prepared as follows.

100 parts of polycarbonate resin (PC1) having the following repeating structure (m: n = 60: 40, weight average molecular weight (Mw) = 47,000, number average molecular weight (Mn) = 19000, viscosity average molecular weight (Mv) = 18,000), 50 parts of the compound represented by the following CT1 as the charge transport material, 8 parts of the product name IRGANOX1076 manufactured by Ciba Specialty Chemicals as the antioxidant, and silicone oil as the leveling agent (Shin-Etsu Silicone) Product: 0.05 part of trade name: KF96) was dissolved in 520 parts of a mixed solvent of THF / toluene (8/2 (weight ratio)) to prepare a coating solution for forming a charge transport layer.

<Manufacture of photoconductor>
The undercoat layer-forming coating solution obtained as described above was applied on a polyethylene terephthalate sheet having aluminum deposited on the surface with a wire bar so that the film thickness after drying was about 1.3 μm, and dried at room temperature. An undercoat layer was provided.
Subsequently, the coating solution for forming the charge generation layer obtained as described above was applied on the undercoat layer with a wire bar so that the film thickness after drying was about 0.3 μm, and dried at room temperature. A charge generation layer was provided.

Subsequently, the coating solution for forming a charge transport layer obtained as described above was applied onto the charge generation layer with an applicator so that the film thickness after drying was about 25 μm, and dried at 125 ° C. for 20 minutes. Thus, a comparative photoreceptor B1 was produced.
[Example 1]
As a resin used for forming the charge transport layer of Comparative Example 1, 25 parts of a polyester resin (PE1, viscosity average molecular weight is 43,000) having PC1: 75 parts and the following structural units was used instead of PC1: 100 parts. Except for the above, a photoconductor A1 was prepared in the same manner as in Comparative Example 1, and the photoconductor was evaluated.

[Example 2]
A photoconductor A2 was prepared in the same manner as in Comparative Example 1 except that PC1: 50 parts and PE1: 50 parts were used instead of PC1: 100 parts as the resin used for forming the charge transport layer of Comparative Example 1. The photoreceptor was evaluated.
[Example 3]
Photoreceptor A3 was prepared in the same manner as in Comparative Example 1 except that instead of 100 parts of PC1, PC1: 25 parts and PE1: 75 parts were used as the resin used to form the charge transport layer of Comparative Example 1, The photoreceptor was evaluated.

[Comparative Example 2]
A comparative photoconductor B2 was prepared in the same manner as in Comparative Example 1 except that the resin used for forming the charge transport layer in Comparative Example 1 was replaced with 1: 100 parts of PC instead of 1: 100 parts of PC, and the photoconductor evaluation was performed. Was done.
[Comparative Example 3]
As a resin used for forming the charge transport layer of Comparative Example 1, instead of PC1: 100 parts, PC2 (m: n = 67: 33, weight average molecular weight (Mw) = 55,000, number average molecular weight of the following structural formula (Mn) = 21,000, viscosity average molecular weight (Mv) = 20,000): A comparative photoreceptor B3 was prepared in the same manner as in Comparative Example 1 except that 100 parts were used, and the photoreceptor was evaluated.

[Example 4]
Photoreceptor A4 was prepared in the same manner as in Comparative Example 3 except that PC2: 100 parts and PC1: 50 parts were used instead of PC2: 100 parts as the resin used in the charge transport layer formation of Comparative Example 3. The photoreceptor was evaluated.
[Comparative Example 4]
As a resin used for forming the charge transport layer of Comparative Example 1, instead of PC1: 100 parts, PC3 (m: n = 80: 20, weight average molecular weight (Mw) = 50,000, number average molecular weight of the following structural formula (Mn) = 20,000, viscosity average molecular weight (Mv) = 19000): A comparative photoconductor B4 was prepared in the same manner as in Comparative Example 1 except that 100 parts were used, and the photoconductor was evaluated.

[Example 5]
A photoconductor A5 was prepared in the same manner as in Comparative Example 4 except that PC3: 50 parts and PE1: 50 parts were used as the resin used for forming the charge transport layer in Comparative Example 4 instead of PC3: 100 parts. The photoreceptor was evaluated.
[Comparative Example 5]
As a resin used for forming the charge transport layer of Comparative Example 1, instead of PC1: 100 parts, PE2 (a: b: c: d = 27: 25: 23: 25, weight average molecular weight (Mw) of the following structural formula = 55,000, number average molecular weight (Mn) = 20,000, viscosity average molecular weight (Mv) = 21,000): A comparative photoconductor B5 was prepared in the same manner as in Comparative Example 1 except that 100 parts were used. The photoreceptor was evaluated.

[ Comparative Example 10 ]
The resin used for forming the charge transport layer of Comparative Example 5 is the same as Comparative Example 5 except that 50 parts of polycarbonate resin (PC1) and PE2: 50 parts having the structural unit are used instead of PE2: 100 parts. A photoconductor A6 was prepared, and the photoconductor was evaluated.
[Comparative Example 6]
Comparative Example 1 except that PC4 (viscosity average molecular weight (Mv) = 20,000): 100 parts of the following structural formula was used as the resin used for forming the charge transport layer of Comparative Example 1 instead of PC1: 100 parts. Comparative Photoreceptor B6 was prepared in the same manner as in Example 1, and the photoreceptor was evaluated.

[Comparative Example 7]
Comparative Photoreceptor B7 was prepared in the same manner as Comparative Example 6 except that PC1: 50 parts and PC4: 50 parts were used as the resin used for forming the charge transport layer in Comparative Example 6 instead of PC4: 100 parts. The photoreceptor was evaluated.
[Comparative Example 8]
Comparative Photoreceptor B8 was prepared in the same manner as Comparative Example 6 except that PC4: 50 parts and PE1: 50 parts were used as the resin used for forming the charge transport layer in Comparative Example 6 instead of PC4: 100 parts. The photoreceptor was evaluated.

[Comparative Example 9]
Comparative Example 1 except that 100 parts of PE3 (viscosity average molecular weight (Mv) = 30,000) of the following structural formula was used as the resin used for forming the charge transport layer of Comparative Example 1 instead of PC1: 100 parts. Comparative Photoreceptor B9 was prepared in the same manner as in Example 1, and the photoreceptor was evaluated.

[Example 7]
A photoconductor A7 was prepared in the same manner as in Comparative Example 9, except that the resin used for forming the charge transport layer in Comparative Example 9 was replaced with PE1: 50 parts and PC1: 50 parts and PE3: 50 parts. The photoreceptor was evaluated.
The obtained photoreceptor was evaluated by the following methods.

<Electrical characteristics test>
Using an electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and applied electrophotographic techniques, edited by the Electrophotographic Society, Corona, page 404-405), the photoreceptor is rotated at 80 rpm. However, the initial surface potential is set to −700 V, and the light of the halogen lamp is changed to a monochromatic light of 780 nm by the interference filter, and the amount of surface potential is changed by using an ND filter having a different transmittance. The decay behavior was measured. At that time, after the exposure with each light amount, the LED light of 660 nm was once exposed as the charge eliminating light, and much of the remaining charge was canceled. As a measured value, a surface potential (bright potential; referred to as VL) when monochromatic light of 780 nm was exposed to 0.40 μJ / cm ² was obtained. The measurement environment was 25 ° C., 50% RH (referred to as NN), 5 ° C., 10% RH (referred to as LL). The results are shown in Table 1.

<Tabor abrasion test>
The photoreceptor film was cut into a circle having a diameter of 10 cm, and the wear was evaluated by a Taber abrasion tester (manufactured by Toyo Seiki Co., Ltd.). The test was conducted under the atmosphere of 23 ° C. and 50% RH using a wear wheel CS-10F, and measuring the weight loss after the test after 1000 rotations without load (self-weight of the wear wheel). The results are shown in Table 1. The smaller the amount of wear, the better the wear resistance.

<Evaluation of physical properties of photoreceptor surface>
The universal hardness and elastic deformation rate were measured in an environment of a temperature of 25 ° C. and a relative humidity of 50% using a microhardness meter FISHERSCOPE H100C manufactured by Fischer. The results are shown in Table 1.
<Adhesiveness>
After the preparation of the sample, the entire base film was cut into the photosensitive layer, and the adhesiveness was evaluated by the peelability from the cut portion. The results are shown in Table 1, where “x” indicates that the cut portion was peeled, and “◯” indicates that there was no change.

  As can be seen from Table 1, the photoconductors B1, B3, and B4 using the polycarbonate resins PC1 to PC3 of the present invention were inferior in wear, but by mixing with the polyester resin, more than expected, that is, each of them. It can be seen that the wear amount is smaller than the simple average of the wear amount of the resin. Moreover, although polycarbonate resin other than this invention or polyester resin alone has a difficulty in adhesiveness, it turns out that it is improving by mixing the polycarbonate resin of this invention.

[Examples 1 'to 5', 7 ' , Comparative Examples 1' to 10 ' ]
<Manufacture of photosensitive drum>
On the aluminum cylinder having an outer diameter of 30 mm, a length of 260.5 mm, and a wall thickness of 0.75 mm, the surface of which has been roughly cut and finished, the above coating solution for forming the undercoat layer and the coating for forming the charge generation layer are applied. The coating solution for forming the liquid and the charge transport layer is sequentially applied and dried by a dip coating method, and the subbing layer, the charge generation layer, and the film thickness are 1.3 μm, 0.4 μm, and 25 μm, respectively, after drying. A charge transport layer was formed to obtain a photoreceptor drum. The charge transport layer was dried at 125 ° C. for 20 minutes. Except for a different substrate, the photosensitive drums C1 to C7 (corresponding to A1 to A7) having the same composition as the sheet photosensitive member and the comparative photosensitive drums D1 to D9 (B1 to B9).
).

<Image test>
The image test was performed using a tandem color laser printer HP Color LaserJet 4700dn (cleaning blade, counter contact method) manufactured by Hewlett-Packard Company.
The produced photosensitive drums C1 to C7 and D1 to D9 were mounted on a cyan process cartridge, and the cartridge was mounted on a printer. Image formation of 10,000 sheets was performed under an environment of a temperature of 25 ° C. and a humidity of 50%, and image defects due to ghost, fog, density reduction, filming, defective cleaning, scratches, and the like were evaluated. The results are shown in Table 2. Similar results were obtained when process cartridges for black, yellow, and magenta were used.

  As can be seen from the results in Table 2, since the photoconductors D1, D3, and D4 using the polycarbonate resins PC1 to PC3 of the present invention are easily worn, scratches may occur after printing a large number of sheets, and the film thickness may be reduced due to wear. Although it is greatly reduced to cause poor charging and fogging occurs on the white background of the image, or cleaning failure occurs, it can be seen that such a problem is solved by mixing the polyester resin. In addition, the polycarbonate resin PC4 or the polyester resin outside the present invention has a difficulty in sounding due to friction with the cleaning blade and adhesion to the lower layer, but it is improved by mixing the polycarbonate resin of the present invention. I understand that

1 Photoconductor
2 Charging device (charging roller)
3 Exposure equipment
4 Development device
5 Transfer device
6 Cleaning device
7 Fixing device
41 Developer tank
42 Agitator
43 Supply roller
44 Developing roller
45 Restriction member
71 Upper fixing member (pressure roller)
72 Lower fixing member (fixing roller)
73 Heating device
T Toner
P Recording paper (paper, medium)

Claims (4)

The outermost surface layer contains at least a polycarbonate resin having a copolymer component represented by the following general formulas (1) and (2) and a polyester resin represented by the following general formula (4). Electrophotographic photoreceptor.

(In the general formula (1), Z forms a cyclic saturated aliphatic alkyl group having 5 to 8 carbon atoms including carbon atoms to be bonded, and the cyclic saturated aliphatic alkyl group has 1 to 3 methyl groups. Group as a substituent.)

(In general formula (2), A ^{1 to} A ⁴ each independently represents a hydrogen atom or a methyl group)

(In the formula (4), Ar ^{1 to} Ar ⁴ each independently represent an arylene group which may have a substituent, and X represents a single bond, an oxygen atom, a sulfur atom, or the following formula (5). Or a group represented by the following formula (6): R ¹ and R ^{2 in} formula (5) each independently represent a hydrogen atom, an alkyl group, or an aryl group, and R ¹ and R ² And R ³ in the formula (6) is an alkylene group, an arylene group, or a group represented by the following formula (7), and in the formula (7) R ⁴ and R ⁵ each independently represents an alkylene group, Ar ⁵ represents an arylene group, k represents an integer of 0 or more, and Y represents a single bond, an oxygen atom, a sulfur atom, or the following formula ( 8) a group represented by formula (8), wherein R ⁶ and R ⁷ are each independently a hydrogen atom,
It represents an alkyl group, an alkoxy group, or an aryl group, and R ⁶ and R ⁷ may combine to form a ring. )

The electrophotographic photosensitive member according to claim 1, wherein the polycarbonate resin is represented by the following structural formula (3).

(In general formula (3), m and n represent molar ratios, and m: n = 90: 10 to 10:90) An electrophotographic photosensitive member according to claim 1 or 2, characterized in that it comprises at least charging means and cleaning means, a process cartridge. An image forming apparatus for forming an image using the electrophotographic photosensitive member according to claim 1 or 2, a charging step of charging said electrophotographic photosensitive member, an exposure to charged the electrophotographic photosensitive member An image forming method including: an exposure step for forming an electrostatic latent image; a development step for developing the electrostatic latent image with toner; a transfer step for transferring the toner to a transfer target; and a cleaning step. Forming equipment.

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