Electrophotographic Imaging System

Abstract

To provide an electrophotographic image forming system that prevents an aggregate derived from an external additive from being fastened in a streak shape while ensuring the charge transport property of a photoreceptor, and achieve both excellent wear resistance of the photoreceptor and good image quality.SOLUTION: An electrophotographic image forming system has a step of forming an electrostatic latent image on a photoreceptor, and a step of bringing a tip ridge part of a cleaning blade into pressure contact with a surface of the photoreceptor to remove a toner for electrostatic charge image development. The photoreceptor has a photosensitive layer, and a surface protective layer provided on a surface of the photosensitive layer. The surface protective layer contains a polymer of a polymerizable monomer having at least two or more polymerizable groups in a molecule, and a hole transport compound having a polymerizable group having a specific structure. The electrophotographic image forming system brings the tip ridge part of the cleaning blade in an obtuse angle shape with an edge angle of 120° or less into pressure contact within a range of an effective contact angle of 8-20°.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic image forming system, and more particularly to an electrophotographic image forming system that ensures charge transport properties of a photoreceptor while suppressing streaky adhesion of aggregates derived from external additives, thereby achieving both excellent wear resistance of the photoreceptor and good image quality. Regarding. [Background technology]

[0002] To extend the life of photoreceptors, increase their hardness, and prevent wear, curable resins made from polyfunctional radical polymerizable monomers are used in the surface protection layer of photoreceptors.

[0003] Furthermore, in order to improve charge transport performance, aromatic compounds having a wide π-conjugated structure are used as hole transport materials (also referred to as "hole transport compounds" in the present invention) in the surface protective layer. In order to achieve both low-wear design and charge transport performance, surface protective layers that use compounds having radical polymerizable groups as the hole transport materials are known.

[0004] Patent Document 1 proposes a cleaning blade that can achieve a surface pressure distribution state that can achieve both wear suppression and toner removal function by using a cleaning blade with an obtuse edge angle at the tip ridge line along with the surface protective layer as described above.

[0005] Patent Document 1 exemplifies a material using a bifunctional triarylamine compound as the hole transport material having a radical polymerizable group.

[0006] On the other hand, image defects may occur due to streaky adhesion of aggregates of toner particles and external additives on the photoreceptor. The mechanism of image defects is speculative, but it is thought to be as follows.

[0007] A portion of the reactive groups of the hole transport compound having a radical polymerizable group or the radical polymerizable monomer constituting the binder remains in the surface protective layer as unreacted groups. The vicinity of the unreacted groups exhibits a locally high adsorption force, making it easier for external additives (silica particles, lubricant particles, etc.) to form aggregates. When these external additive aggregates reach the edge of the cleaning blade, they may be trapped in the narrow wedge space between the photoreceptor and the cleaning blade, located downstream of the edge in the direction of photoreceptor rotation. Over time, they grow into larger aggregates. As a result, the external additives transfer from the aggregates to the photoreceptor and adhere, growing into streaky deposits that also entrain the toner. The presence of these streaky deposits results in unexposed areas, resulting in white spots and poor image quality.

[0008] The configuration disclosed in Patent Document 1 is not intended to improve the problem of streaky adhesion of aggregates derived from the external additives, and simply adjusting the surface pressure distribution of the cleaning blade was not effective enough to prevent the occurrence of the streaky adhesion. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-237588 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved is to provide an electrophotographic image forming system that suppresses streaky adhesion of aggregates derived from external additives while ensuring the charge transport properties of the photoreceptor, thereby achieving both excellent wear resistance of the photoreceptor and good image quality. [Means for solving the problem]

[0011] In the course of investigating the causes of the above problems in order to solve the above problems, the present inventors have found that an electrophotographic image forming system can be obtained in which the surface protective layer of a photosensitive member contains a specific hole transport compound, and the tip ridge portion of a cleaning blade having a specific edge angle is pressed against the surface of the photosensitive member so that the effective contact angle is within a specific range, thereby preventing aggregates derived from external additives from adhering in a streak-like manner while ensuring the charge transport properties of the photosensitive member, and achieving both excellent wear resistance of the photosensitive member and good image quality.

[0012] That is, the above-mentioned problems of the present invention are solved by the following means.

[0013] 1. forming an electrostatic latent image on at least a photoreceptor; developing the image using a toner for developing an electrostatic image; and removing the toner for developing the electrostatic image by pressing a ridge portion of a cleaning blade against the surface of the photosensitive member, the photoreceptor has a photosensitive layer and a surface protective layer provided on the surface of the photosensitive layer, the surface protective layer contains at least a polymerizable monomer having two or more polymerizable groups in the molecule, and a polymer of a hole transport compound having a polymerizable group of a structure represented by the following general formula (1): the electrostatic image developing toner contains a fatty acid metal salt as an external additive, and the amount of the fatty acid metal salt added is 0.15% by mass or more based on the toner base particles; and, An electrophotographic image forming system characterized in that the tip edge of a cleaning blade having an obtuse edge angle of 120° or less is pressed against the surface of the photosensitive member at an effective contact angle in the range of 8 to 20°.

[0014] [ka]

[0015] (In the formula, Ar 1 and Ar 2 represents a linking group represented by the following structural formula (7): Ar 5 represents a group represented by the following structural formula (8) or (9). Ar 5 In the case of structural formula (8), the total number of D ( c1+c2+c5 ) is 1 or 2, Ar 5 In the case of structural formula (9), the total number of D ( c1+c2+c5 ) is 1.

[0016] [ka]

[0017] * indicates the linking position with N or D. c1, c2 and c5 each independently represent 0 or 1. When c1, c2 and c5 each independently represent 0, a hydrogen atom is bonded to the linking position with D. When c1, c2 and c5 each independently represent 1, D is -(-(CH2) d -(O-(CH2) f -) e -O-CO-C(CH3)=CH2) or -(-(CH2) d -(O-(CH2) f -) e -O-CO-CH=CH2). d and f each independently represent an integer of 0 or more and 5 or less. e represents 0 or 1. 。 before Record R 5 and R 6 each independently represents one member selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom. t represents an integer of 1 to 3. R 6 The two may be bonded to each other, and the structural formula (9) may have a cyclic structure.

[0018] 2. Cleaning blade Do 2. The electrophotographic imaging system according to claim 1, wherein the ratio (L / d) of the free length L to the thickness d is 3.5 or more.

[0019] 3. The Ar of the hole transport compound 5 is a linking group represented by the structural formula (9), and the total number of Ds (c 1 +c 2 +c 53. The electrophotographic imaging system according to claim 1, wherein ≡1 is 1.

[0020] 4. The electrophotographic imaging system according to claim 3, wherein at least one of d and e in the structural formula of D of the hole transporting compound is 1 or greater.

[0021] 5. The electrophotographic image forming system according to any one of items 1 to 4, wherein the effective contact angle is within a range of 9 to 17 degrees.

[0022] 6. The electrophotographic image forming system according to any one of items 1 to 5, wherein the edge angle is within a range of 95 to 110°.

[0024] 7 The hole transport compound Polymer of The surface protective layer contains 30 to 70% by mass of the 6 Item 10. The electrophotographic image forming system according to any one of items 1 to 9. [Effects of the Invention]

[0025] The above-described means of the present invention can provide an electrophotographic image forming system that can suppress streaky adhesion of aggregates derived from external additives while ensuring the charge transport properties of the photoreceptor, thereby achieving both excellent wear resistance of the photoreceptor and good image quality.

[0026] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0027] A portion of the reactive groups of the polymerizable monomer constituting the binder or the hole transport compound having a polymerizable group remains in the surface protective layer as unreacted groups. The vicinity of the unreacted groups is locally in a state of high adsorption, which makes it easy for external additives (silica particles, lubricant particles, etc.) to form aggregates. These aggregates become streaky deposits, causing image defects such as white spots. Therefore, it is presumed that reducing the unreacted groups in the surface protective layer can suppress the occurrence of image defects caused by streaky deposits.

[0028] As a result of investigations, the present inventors have found that when the hole transport compound contained in the surface protective layer of a photoreceptor is a compound having a monofunctional (also referred to as "monofunctional") polymerizable group or a compound having a small molecular size of the π-conjugated moiety, the steric hindrance during the curing reaction is reduced, thereby making it possible to reduce the amount of unreacted groups remaining in the surface protective layer.

[0029] This is because, in the case of a bifunctional hole transport material, the reaction of the first reactive group of the hole transport material results in the hole transport material being directly bonded to the binder and being in a constrained state, resulting in increased steric hindrance during the reaction of the second reactive group. However, even in the case of a bifunctional hole transport material, if the molecular size of the π-conjugated moiety is small, the degree of freedom of movement of the hole transport material is relatively ensured, even when it is in a state of being constrained to the binder via the first reaction site, and the number of unreacted groups can be reduced.

[0030] Furthermore, by pressing the tip ridge of the cleaning blade at an appropriate effective contact angle, the width of the wedge space between the photosensitive element and the cleaning blade downstream in the rotation direction from the tip ridge (edge) of the cleaning blade is ensured, and even if aggregates reach the cleaning blade, accumulation on the edge of the cleaning blade can be suppressed.

[0031] In this case, if the cleaning blade edge is a right-angled shape, increasing the effective contact angle increases the amount of retraction of the blade edge, which poses the risk of poor cleaning due to curling or increased vibration.However, if the edge is an obtuse angle, the amount of retraction decreases, allowing the effective contact angle to be increased without causing curling or increased vibration.

[0032] The synergistic effect of the appropriate selection of the hole transport compound and the specific cleaning blade configuration ensures the charge transport properties of the photoreceptor while suppressing streaky adhesion of aggregates derived from external additives, thereby achieving both excellent wear resistance of the photoreceptor and good image quality. [Brief explanation of the drawings]

[0033] [Figure 1] Schematic diagram showing the deposition state of aggregates when a hole transport compound and a cleaning blade other than those of the present invention are used. [Figure 2] A conceptual diagram showing the deposition state of aggregates when the hole transport compound and cleaning blade according to the present invention are used. [Figure 3] A conceptual side view of the relationship between the cleaning blade and the electrophotographic photosensitive member according to the present invention. [Figure 4] FIG. 1 is a cross-sectional view illustrating an example of the configuration of an image forming apparatus according to the present invention. [Figure 5] FIG. 1 is a cross-sectional view illustrating an example of the configuration of a main part of an image forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0034] The electrophotographic image forming system of the present invention includes the steps of forming an electrostatic latent image on a photoreceptor, developing the image with a toner for developing the electrostatic image, and pressing a ridge of a cleaning blade against the surface of the photoreceptor to remove the toner for developing the electrostatic image, wherein the photoreceptor has a photosensitive layer and a surface protective layer provided on the surface of the photoreceptor, the surface protective layer containing at least a polymerizable monomer having two or more polymerizable groups in its molecule and a polymer of a hole-transporting compound having a polymerizable group represented by the general formula (1), and the ridge of a cleaning blade having an obtuse edge angle of 120° or less is pressed against the surface of the photoreceptor at an effective contact angle of 8 to 20°. This feature is a technical feature common to or corresponding to the following embodiments.

[0035] In an embodiment of the present invention, from the viewpoint of achieving the effects of the present invention, it is preferable that the ratio (L / d) of the free length L to the thickness d of the cleaning blade is 3.5 or more.

[0036] This is because the surface pressure at the tip of the cleaning blade is not completely uniform in the longitudinal direction, and there are areas where the surface pressure is locally high and low in the longitudinal direction due to minute vibrations at the tip of the blade that occur when the blade is driven, etc. In areas where the surface pressure is locally low, the external additives in particular tend to slip through the nip of the cleaning blade, making it easier for the external additives to aggregate at the edge.

[0037] When the ratio of thickness to free length is 3.5 or more, the blade rubber bends and assumes a position in which the rubber part bites into the photosensitive member. This reduces the variation in longitudinal surface pressure distribution even when vibrations are generated during operation, making it possible to more effectively suppress the generation of external additive agglomerates.

[0038] In addition, the Ar 5is the structural formula (9) and the total number of D is 1. The biphenyl structure provides a structure with a wider π-conjugation than the triphenylamine skeleton, and therefore the desired charge transport function can be achieved with a smaller blending ratio relative to the entire surface protective layer. As a result, this is a preferred embodiment from the viewpoint of further reducing unreacted groups in the surface protective layer.

[0039] It is preferable that at least one of d and e in the structure of D of the hole transport compound is 1 or greater, because the reactive group moiety is not constrained by the π-conjugated moiety and can move relatively freely during the curing reaction, compared to the case where the (meth)acryloyl group, which is a polymerizable reactive group, is directly bonded to a highly rigid π-conjugated moiety (aromatic ring moiety), i.e., the case where both d and e are 0, and therefore the amount of remaining unreacted groups can be further reduced.

[0040] The reason why it is preferable that the effective contact angle is in the range of 9 to 17° and the edge angle is in the range of 95 to 110° is as follows.

[0041] By maintaining a moderately large effective contact angle, the width of the wedge space between the photosensitive element and the blade downstream of the edge of the cleaning blade in the direction of rotation is ensured, and even if aggregates reach the cleaning blade, deposition on the blade edge is suppressed.

[0042] However, if the effective contact angle is too large, the amount of retraction of the blade edge increases, which may result in poor cleaning due to blade curling or increased stick-slip vibration, so it is preferable that the effective contact angle is within the above range.

[0043] Furthermore, in the present invention, since the edge angle of the cleaning blade is an obtuse angle, the amount of retraction of the edge of the cleaning blade itself is small, and therefore the effective contact angle can be set larger than when the edge angle is not an obtuse angle.

[0044] If the edge angle is too large, the surface pressure of the blade edge decreases, making it easier for the external additive to slip through the blade, which may result in the external additive being more likely to accumulate on the blade edge even when the effective contact angle is ensured.

[0045] By setting the above-mentioned effective contact angle and edge angle within the ranges according to the present invention, the width of the wedge space sandwiched between the photosensitive element and the blade downstream of the edge of the cleaning blade in the direction of rotation is ensured, and even if aggregates reach the cleaning blade, accumulation on the edge of the cleaning blade is suppressed.

[0046] Furthermore, it is preferable that the photoreceptor further contains a fatty acid metal salt, and that the amount of the fatty acid metal salt added is 0.15% by mass or more relative to the toner base particles, from the viewpoint that by coating the surface of the photoreceptor with the fatty acid metal salt and making the surface hydrophobic, the generation of aggregates can be more effectively suppressed even in the presence of unreacted groups.

[0047] Furthermore, it is preferable that the hole transport compound is contained in the surface protective layer in an amount of 30 to 70% by mass, from the viewpoint of further reducing unreacted groups in the surface protective layer.

[0048] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0049] <<Outline of the Electrophotographic Image Forming System of the Present Invention>> The electrophotographic image forming system of the present invention comprises at least the steps of forming an electrostatic latent image on a photoreceptor, developing the image with toner for developing the electrostatic image, and removing the toner for developing the electrostatic image by pressing a ridgeline of a cleaning blade against the surface of the photoreceptor, wherein the photoreceptor has a photosensitive layer and a surface protective layer provided on the surface of the photosensitive layer, and the surface protective layer contains at least a polymerizable monomer having two or more polymerizable groups in the molecule and a polymer of a hole transport compound having a polymerizable group of the structure represented by the general formula (1), and the ridgeline of a cleaning blade having an obtuse edge angle of 120° or less is pressed against the surface of the photoreceptor at an effective contact angle in the range of 8 to 20°.

[0050] FIG. 1 is a conceptual diagram showing the deposition state of aggregates when a hole transporting compound other than that of the present invention and a cleaning blade are used.

[0051] For example, a hole transport compound having a radical polymerizable group, or a portion of the reactive groups of the radical polymerizable monomer constituting the binder, remain as unreacted groups in the surface protective layer 1. When a hole transport compound outside the present invention is used in the surface protective layer, there is much steric hindrance during the curing reaction, and a large amount of unreacted groups remain in the surface protective layer, which makes it easy for the external additive lubricant particles 2 to adhere locally, and as a result, a large amount of solidified material due to aggregates derived from the external additive accumulates on the cleaning blade 3, causing streaky adhesion and image defects such as white spots.

[0052] On the other hand, FIG. 2 is a conceptual diagram showing the deposition state of aggregates when the hole transporting compound and cleaning blade according to the present invention are used.

[0053] The hole-transporting compound contained in the surface protective layer 1 according to the present invention is either a compound having a monofunctional radically polymerizable group or a compound having a small molecular size at the π-conjugated portion, thereby reducing steric hindrance during the curing reaction and reducing the amount of unreacted groups remaining in the surface protective layer. This prevents the external additive lubricant particles 2 from becoming prone to localized adhesion. Furthermore, by increasing the effective contact angle β of the cleaning blade 3 from the effective contact angle α in FIG. 1 to a slightly larger angle, the wedge space 4 can be made wider, further suppressing the accumulation of aggregates derived from the external additive. This reduces the occurrence of streaky adhesion and significantly reduces image defects such as whiteouts.

[0054] The configuration according to the present invention will be described in detail below. [1] Electrophotographic photoreceptor The electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor (hereinafter simply referred to as "photoreceptor") for use in an electrophotographic photosensitive type image forming apparatus, and the electrophotographic photoreceptor has a conductive support, a photosensitive layer, and a surface protective layer.

[0055] The surface protective layer of the photoreceptor contains at least a polymerizable monomer having two or more polymerizable groups in the molecule, and a hole transporting compound having a structure represented by the following general formula (1).

[0056] However, the photoreceptor may include other structures as long as the objects and effects of the present invention are not impaired. For example, other layers such as an intermediate layer may be provided between the conductive support and the photosensitive layer as needed. The layer structure of the photoreceptor is not particularly limited and is appropriately selected depending on the performance and application required of the photoreceptor.

[0057] For example, the conductive support / charge generating layer / charge transport layer / surface protective layer may be laminated in this order, or the conductive support / charge generating / transport layer / surface protective layer may be laminated in this order.

[0058] Alternatively, the conductive support / intermediate layer / charge generation layer / charge transport layer / surface protective layer may be laminated in this order, or the conductive support / intermediate layer / charge generation / transport layer / surface protective layer may be laminated in this order.

[0059] [1.1] Surface protective layer First, the "surface protective layer" which is a feature of the present invention will be described.

[0060] The surface protective layer according to the present invention is characterized by containing at least a polymerizable monomer having two or more polymerizable groups in the molecule, and a polymer of a hole transport compound having a polymerizable group having a structure represented by the following general formula (1):

[0061] The polymerizable monomer having at least two polymerizable groups in the molecule is generally also called a "polyfunctional polymerizable compound" or a "polyfunctional polymerizable monomer." The polyfunctional polymerizable compound includes a polyfunctional polymerizable compound having a hole transport property and a polyfunctional polymerizable compound not having a hole transport property. In the present invention, the "polymerizable monomer having two or more polymerizable groups in the molecule" refers to a "polyfunctional polymerizable compound not having a hole transport property."

[0062] As the polyfunctional polymerizable compound not having hole transport properties, for example, a monomer having a radical polymerizable functional group and polymerizing (curing) with a radical polymerization initiator to form a binder resin of a photoreceptor is preferably used, and from the viewpoint of maintaining high durability, a crosslinkable polymerizable compound is preferably used. Specific examples of the crosslinkable polymerizable compound include polymerizable compounds having two or more radical polymerizable functional groups, such as polystyrene, polyacrylate, or polycarbonate. Specific examples thereof include the compounds described below.

[0063] Here, the term "hole transporting property" in the present invention refers to a property of having a higher hole transporting ability than an electron transporting ability, that is, a property in which the hole mobility is higher than the electron mobility.

[0064] An ionization potential (the energy required to remove an electron from a neutral molecule to ionize it) of 6.2 eV or less is preferred in that hole injection occurs easily, and a value within the range of 4.5 to 6.2 eV is particularly preferred in terms of preventing oxidation of the compound.

[0065] The hole transport capacity is 1×10 -7 cm 2 Preferably, the electron transport layer has a drift mobility of 1 / Vsec or more.

[0066] The method for measuring hole or electron mobility is not particularly limited. Specific examples of the method include the following. (1) Time of flight method (a method of calculating the transit time of charges in an organic film) (2) Calculation method from the voltage characteristics of the space charge limited current (3) Method of determining from the peak frequency measured by impedance spectroscopy

[0067] Examples of the "polymerizable compound having hole transport properties" include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and compounds having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred, and specifically, they are compounds having a structure represented by general formula (1) described below.

[0068] Further, examples of the "polymerizable compound having hole transport properties" include, in addition to the polyfunctional polymerizable compounds, polymerizable compounds having one polymerizable group in the molecule contained in a compound having a structure represented by general formula (1) (also referred to as "monofunctional polymerizable compound" or "monofunctional polymerizable monomer").

[0069] Therefore, the surface protective layer according to the present invention is a cured product of a coating liquid (also referred to as a "coating liquid for forming a surface protective layer") containing the polyfunctional polymerizable compound or monofunctional polymerizable compound having hole transport properties, and a polyfunctional polymerizable compound not having hole transport properties.

[0070] Furthermore, the coating liquid preferably contains a photopolymerization initiator and inorganic particles, and may contain a known charge transport material other than the polyfunctional or monofunctional polymerizable compound having hole transport properties.

[0071] The following describes in order: (1) a polyfunctional or monofunctional polymerizable compound having hole-transport properties (a hole-transport compound having a polymerizable group having a structure represented by general formula (1) according to the present invention), (2) a polyfunctional polymerizable compound not having hole-transport properties, (3) a photopolymerization initiator, (4) inorganic particles, (5) other additives, and (6) physical properties of the surface protective layer.

[0072] (1) A hole transporting compound having a polymerizable group represented by the general formula (1): As described above, when the hole transport compound contained in the surface protective layer of the photoreceptor is a compound having a monofunctional radically polymerizable group or a compound having a small molecular size at the π-conjugated moiety, steric hindrance during the curing reaction is reduced, and the amount of unreacted groups remaining in the surface protective layer can be reduced.

[0073] This is because, in the case of a bifunctional hole transport material, the reaction of the first reactive group of the hole transport material results in the hole transport material being directly bonded to the binder and being in a constrained state, resulting in increased steric hindrance during the reaction of the second reactive group. However, even in the case of a bifunctional hole transport material, if the molecular size of the π-conjugated moiety is small, the degree of freedom of movement of the hole transport material is relatively ensured, even when it is in a state of being constrained to the binder via the first reaction site, and the number of unreacted groups can be reduced.

[0074] The compound having a structure represented by general formula (1) contained in the surface protective layer according to the present invention is represented by the following structural formula.

[0075] [ka]

[0076] In the formula, Ar 1 and Ar 2 represents a linking group represented by the following structural formula (7): Ar 5 represents a group represented by the following structural formula (8) or (9). Ar 5 If structural formula (8) is the total number of D (c 1 +c 2 +c 5 ) is 1 or 2, Ar 5 In the case of structural formula (9), the total number of D (c 1 +c 2 +c 5 ) is 1.

[0077] [ka]

[0078] D is -(-(CH2) d -(O-(CH2) f -) e -O-CO-C(CH3)=CH2) or -(-(CH2) d -(O-(CH2) f -) e -O-CO-CH=CH2). d and f each independently represent an integer of 0 or more and 5 or less. e represents 0 or 1. c 1 ~c 5 each independently represents 0, 1 or 2.

[0079] R 5 and R 6 each independently represents one member selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom. t represents an integer of 1 to 3. R 6The two may be bonded to each other, so that the structural formula (9) has a cyclic structure.

[0080] The Ar of the hole transport compound 5 is the structural formula (9) and the total number of D is 1. The biphenyl structure provides a structure with a wider π-conjugation than the triphenylamine skeleton, and therefore the desired charge transport function can be achieved with a smaller blending ratio relative to the entire surface protective layer. As a result, this is a preferred embodiment from the viewpoint of further reducing unreacted groups in the surface protective layer.

[0081] Furthermore, it is preferable that at least one of d and e in the structural formula of D of the hole transport compound is 1 or greater, because compared with the case where a (meth)acryloyl group, which is a polymerizable reactive group, is directly bonded to a highly rigid π-conjugated moiety (aromatic ring moiety), i.e., the case where both d and e are 0, the reactive group moiety is not constrained by the π-conjugated moiety during the curing reaction and can move relatively freely, thereby further reducing the amount of remaining unreacted groups.

[0082] Specific examples of the hole transporting compound having the structure represented by general formula (1) are shown below, but the invention is not limited to these.

[0083] Examples of compounds in which the total number of D is 1, that is, compounds having one (meth)acryloyl group, are shown below.

[0084] [ka]

[0085] [ka]

[0086] [ka]

[0087] [ka]

[0088] Ar 5 The following are examples of compounds having the structural formula (8) where the total number of D is 2, i.e., compounds having two (meth)acryloyl groups.

[0089] [ka]

[0090] The hole transporting compound having the structure represented by the general formula (1) exemplified above can be synthesized according to the synthetic route for the compounds having the structures represented by the general formulae A1, A2 and A3 shown below.

[0091] (Synthetic route for compounds of general formula A1)

[0092] [ka]

[0093] In general formula A1, R 1 represents a hydrogen atom or a methyl group. 2 and R 3 each independently represents an alkyl group having 1 to 3 carbon atoms; x and y each independently represent an integer of 0 to 2; n represents an integer of 1 to 3; R 2 If there are multiple R 2 may be the same or different. 3 If there are multiple R 3 may be the same or different.

[0094] (Synthetic route for compounds of general formula A2)

[0095] [ka]

[0096] In general formula A2, R 1 represents a hydrogen atom or a methyl group. 2 and R 3 each independently represents an alkyl group having 1 to 3 carbon atoms; x and y each independently represent an integer of 0 to 2; n represents an integer of 1 to 3; R 2 If there are multiple R 2 may be the same or different. 3 If there are multiple R 3 may be the same or different.

[0097] (Synthetic route for compounds of general formula A3)

[0098] [ka]

[0099] In general formula A3, R 1 represents a hydrogen atom or a methyl group. 2 Each of x independently represents an alkyl group having 1 to 3 carbon atoms. Each of x independently represents an integer of 0 to 2. n represents an integer of 1 to 3. R 2 If there are multiple R 2 may be the same or different.

[0100] The hole transport compound is preferably contained in the surface protective layer in an amount of 30 to 70% by mass, from the viewpoint of further reducing unreacted groups in the surface protective layer. 5 is a linking group represented by the structural formula (9), and the total number of Ds (c 1 +c 2 +c 5 It is preferred to use a compound in which ) is 1.

[0101] The hole transporting compounds may be used alone or in combination.

[0102] (2) Polyfunctional polymerizable compound without hole transport properties Specific examples of polyfunctional polymerizable compounds (polyfunctional polymerizable monomers) having two or more polymerizable groups in the molecule that do not have hole transport properties are shown below, but the invention is not limited to these.

[0103] [ka]

[0104] [ka]

[0105] In the chemical formulas showing the above exemplary compounds M1 to M14, R represents an acryloyl group (CH2=CHCO-), and R' represents a methacryloyl group (CH2=CCH3CO-).

[0106] (3) Photopolymerization initiator The photopolymerization initiator used in the present invention is not particularly limited, but from the viewpoint of more reliably suppressing side effects such as a decrease in memory resistance, for example, a monomolecular photopolymerization initiator having an acylphosphine oxide structure or an O-acyloxime structure is preferred. These may be used alone or in combination. In the present invention, a monomolecular photopolymerization initiator refers to one in which one molecule functions as a photopolymerization initiator by itself, and a bimolecular photopolymerization initiator refers to one in which two or more molecules are combined to function as a photopolymerization initiator.

[0107] Specific examples of the photopolymerization initiator having an acylphosphine oxide structure are shown below.

[0108] [ka]

[0109] Of the two, Irgacure TPO (manufactured by BASF Japan Ltd.) and Irgacure 819 (manufactured by BASF Japan Ltd.), Irgacure 819 is more preferable.

[0110] Examples of photopolymerization initiators having an O-acyloxime structure include Irgacure OXE02 (manufactured by BASF Japan Ltd.) and the compounds shown below.

[0111] [ka]

[0112] In the present invention, the photopolymerization initiator having an O-acyloxime structure is preferably a photopolymerization initiator having a structure represented by the following general formula (a-3).

[0113] [ka]

[0114] In general formula (a-3), R1 and R2 each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 6 carbon atoms which may have a substituent, or an aryl group which may have a substituent.

[0115] R3 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, an aryl group which may have a substituent, a halogen atom, a cyano group, a nitro group, a hydroxy group, or a carbonyl group which may have a substituent.

[0116] Examples of the alkyl group in general formula (a-3) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a (t)butyl group, a pentyl group, a hexyl group, an octyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, and a benzyl group. Examples of the cycloalkyl group in general formula (a-3) include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the aryl group in general formula (a-3) include a phenyl group, a p-chlorophenyl group, a mesityl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group, an azulenyl group, an acenaphthenyl group, a fluorenyl group, a phenanthryl group, an indenyl group, a pyrenyl group, and a biphenylyl group. Examples of the alkoxy group in the general formula (a-3) include a methoxy group, an ethoxy group, a propyloxy group, a butoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, and a dodecyloxy group.

[0117] These substituents may be further substituted with the above-mentioned substituents, or may be condensed with each other to form a ring.

[0118] Specific examples of compounds having the structure represented by the above general formula (a-3) are shown below.

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] Commercially available photopolymerization initiators having an O-acyloxime structure include, for example, Irgacure OXE01 (manufactured by BASF Japan Ltd.), which is the above-mentioned exemplary compound B-1, as well as PBG-305 and PBG-329 (both manufactured by Changzhou Strong Electronic New Materials Co., Ltd.), which are O-acyloxime initiators having a disulfide structure in the compound.

[0124] The photopolymerization initiator used in the present invention is not limited to the monomolecular photopolymerization initiators described above, but may also be a bimolecular photopolymerization initiator, such as a combination of a compound having a hexaarylbisimidazole structure and a thiol compound.

[0125] Specific examples of compounds having a hexaarylbisimidazole structure that can be used as bimolecular photopolymerization initiators are shown below.

[0126] [ka]

[0127] Specific examples of thiol compounds used in bimolecular photopolymerization initiators are shown below.

[0128] [ka]

[0129] Furthermore, the proportion of the photopolymerization initiator added is preferably within a range of 0.1 to 10 volume percent, and more preferably within a range of 1 to 5 volume percent, relative to 100 volume percent of the solid content of the coating liquid for forming the surface protective layer, as described below.

[0130] In addition to the above-mentioned photopolymerization initiator, other known photopolymerization initiators may also be contained.

[0131] (4) Inorganic particles The surface protective layer according to the present invention preferably contains inorganic particles, and more preferably contains metal oxide particles as the inorganic particles.

[0132] The metal oxide particles are preferably metal oxide fine particles, including transition metals. Examples include metal oxide particles such as silica (silicon dioxide), magnesium oxide, zinc oxide, lead oxide, aluminum oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium oxide, niobium oxide, molybdenum oxide, and vanadium oxide. Among these, tin oxide fine particles, titanium oxide fine particles, zinc oxide fine particles, and alumina fine particles are preferred because they can improve the abrasion resistance of the surface protective layer.

[0133] The metal oxide particles are preferably produced by a known method, such as a general production method including a gas phase method, a chlorine method, a sulfuric acid method, a plasma method, and an electrolytic method.

[0134] The number average primary particle size of the metal oxide particles is, for example, preferably within a range of 1 to 300 nm, and particularly preferably within a range of 3 to 100 nm.

[0135] Furthermore, the proportion of metal oxide particles added is preferably within the range of 0.1 to 30 volume percent, and more preferably within the range of 1 to 20 volume percent, relative to 100 volume percent of the solid content of the coating liquid for forming the surface protective layer, as described below.

[0136] (4.1) Method for measuring the particle size of metal oxide particles The particle size (number-average primary particle size) of the metal oxide particles was determined by taking a 10,000x magnification photograph using a scanning electron microscope (manufactured by JEOL Ltd.), randomly selecting 300 particles, scanning the photographic image (agglomerated particles were excluded), and binarizing the image using an automatic image processing analyzer "LUZEX (registered trademark) AP" (manufactured by Nireco Corporation) software version 1.32 to calculate the horizontal Feret diameter for each particle, and calculating the average of these values ​​as the number-average primary particle size. Here, the horizontal Feret diameter refers to the length of the side parallel to the x-axis of the circumscribed rectangle when the image of the metal oxide particle is binarized.

[0137] (4.2) Surface modification In the present invention, the metal oxide particles preferably have a reactive organic group. That is, from the viewpoints of dispersibility and abrasion resistance of the photoreceptor, the metal oxide particles are preferably surface-modified with a surface modifier having a reactive organic group.

[0138] As the surface modifier, a surface modifier that reacts with hydroxy groups or the like present on the surface of the metal oxide particles before surface modification may be used. Examples of such surface modifiers include silane coupling agents and titanium coupling agents.

[0139] In the present invention, for the purpose of further increasing the hardness of the surface protective layer, it is preferable to use a surface modifier having a reactive organic group, and it is more preferable to use one in which the reactive organic group is a radically polymerizable functional group. By using a surface modifier having a radically polymerizable functional group, it is possible to form a strong protective film by reacting with the radically polymerizable compound for the binder and the charge transport material contained in the surface protective layer.

[0140] As the surface modifying agent having a radically polymerizable functional group, it is preferable to use a silane coupling agent having an acryloyl group or a methacryloyl group. Examples of such a surface modifying agent having a radically polymerizable functional group include known compounds such as those described below.

[0141] S-1:CH2=CHSi(CH3)(OCH3)2 S-2:CH2=CHSi(OCH3)3 S-3:CH2=CHSiCl3 S-4:CH2=CHCOO(CH2)2Si(CH3)(OCH3)2 S-5:CH2=CHCOO(CH2)2Si(OCH3)3 S-6:CH2=CHCOO(CH2)2Si(OC2H5)(OCH3)2 S-7:CH2=CHCOO(CH2)3Si(OCH3)3 S-8:CH2=CHCOO(CH2)2Si(CH3)Cl2 S-9:CH2=CHCOO(CH2)2SiCl3 S-10:CH2=CHCOO(CH2)3Si(CH3)Cl2 S-11:CH2=CHCOO(CH2)3SiCl3 S-12:CH2=C(CH3)COO(CH2)2Si(CH3)(OCH3)2 S-13:CH2=C(CH3)COO(CH2)2Si(OCH3)3 S-14:CH2=C(CH3)COO(CH2)3Si(CH3)(OCH3)2 S-15:CH2=C(CH3)COO(CH2)3Si(OCH3)3 S-16:CH2=C(CH3)COO(CH2)2Si(CH3)Cl2 S-17:CH2=C(CH3)COO(CH2)2SiCl3 S-18:CH2=C(CH3)COO(CH2)3Si(CH3)Cl2 S-19:CH2=C(CH3)COO(CH2)3SiCl3 S-20:CH2=CHSi(C2H5)(OCH3)2 S-21:CH2=C(CH3)Si(OCH3)3 S-22:CH2=C(CH3)Si(OC2H5)3 S-23:CH2=CHSi(OCH3)3 S-24:CH2=C(CH3)Si(CH3)(OCH3)2 S-25: CH2=CHSi(CH3)Cl2 S-26: CH2=CHCOOSi(OCH3)3 S-27: CH2=CHCOOSi(OC2H5)3 S-28: CH2=C(CH3)COOSi(OCH3)3 S-29: CH2=C(CH3)COOSi(OC2H5)3 S-30:CH2=C(CH3)COO(CH2)3Si(OC2H5)3 S-31:CH2=CHCOO(CH2)2Si(CH3)2(OCH3) S-32:CH2=CHCOO(CH2)2Si(CH3)(OCOCH3)2 S-33:CH2=CHCOO(CH2)2Si(CH3)(ONHCH3)2 S-34:CH2=CHCOO(CH2)2Si(CH3)(OC6H5)2 S-35: CH2=CHCOO(CH2)2Si(C 10 H 21 )(OCH3)2 S-36:CH2=CHCOO(CH2)2Si(CH2C6H5)(OCH3)2

[0142] In addition to the above S-1 to S-36, a silane compound having a reactive organic group capable of undergoing a radical polymerization reaction can also be used as the surface modifier. These surface modifiers can be used alone or in combination of two or more.

[0143] The amount of the surface modifier used is not particularly limited, but is preferably within the range of 0.1 to 100 parts by mass per 100 parts by mass of the metal oxide particles before modification.

[0144] (4.3) Method for surface modification of metal oxide particles Specifically, the surface modification of metal oxide particles can be carried out by wet-pulverizing a slurry (a suspension of solid particles) containing unmodified metal oxide particles and a surface modifier, thereby reducing the size of the metal oxide particles and simultaneously promoting the surface modification of the particles, and then removing the solvent to obtain a powder.

[0145] The slurry is preferably prepared by mixing 100 parts by mass of unmodified metal oxide particles with 0.1 to 100 parts by mass of surface modifier and 50 to 5000 parts by mass of solvent.

[0146] Furthermore, as an apparatus used for wet-pulverizing the slurry, a wet media dispersion type apparatus can be mentioned.

[0147] A wet media dispersion device is a device that uses beads as media in a container and then rotates a stirring disk attached perpendicular to the rotation axis at high speed to crush, pulverize, and disperse agglomerates of metal oxide particles. The device can be configured in any manner that can sufficiently disperse and surface-modify the metal oxide particles when surface-modifying them, and various types, such as vertical or horizontal, continuous or batch, can be used. Specifically, sand mills, Ultraviscomills, pearl mills, grain mills, Dynomills, agitator mills, and dynamic mills can be used. These dispersion devices use grinding media such as balls or beads to perform fine grinding and dispersion through impact crushing, friction, shear, and shear stress.

[0148] The beads used in the wet media dispersion device may be balls made from raw materials such as glass, alumina, zircon, zirconia, steel, flint, etc., but it is particularly preferable to use those made from zirconia or zircon. Furthermore, the size of the beads is usually about 1 to 2 mm in diameter, but in the present invention, it is preferable to use those about 0.1 to 1.0 mm.

[0149] The disks and inner walls of the container used in the wet media dispersion device can be made of various materials, such as stainless steel, nylon, and ceramic. In the present invention, however, it is particularly preferable that the disks and inner walls of the container are made of ceramics such as zirconia or silicon carbide.

[0150] (5) Other additives The surface protective layer according to the present invention may contain other components, such as known charge transport materials, various antioxidants, and various lubricant particles such as fluorine atom-containing resin particles.

[0151] As a known charge transport substance, for example, the charge transport substances described in paragraphs

[0064] to

[0108] of JP-A-2018-124489 can be used.

[0152] As the fluorine atom-containing resin particles, it is preferable to appropriately select one or more from, for example, tetrafluoroethylene resin, trifluorochloroethylene resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloroethylene resin, and copolymers thereof, with tetrafluoroethylene resin and vinylidene fluoride resin being particularly preferred.

[0153] [1.2] Conductive support The support used in the photoreceptor according to the present invention may be any structure that is electrically conductive and capable of supporting the photosensitive layer, such as a cylindrical or columnar structure.

[0154] The size of the conductive support is appropriately selected depending on the application of the electrophotographic photoreceptor.

[0155] The material of the conductive support is not particularly limited.

[0156] Examples of conductive supports include metals such as aluminum, copper, chromium, nickel, zinc, and stainless steel molded into a drum or sheet shape; metal foils such as aluminum and copper laminated onto drum-shaped or sheet-shaped plastic films; drum-shaped or sheet-shaped plastic films onto which aluminum, indium oxide, tin oxide, or the like has been vapor-deposited; and drum-shaped or sheet-shaped metals, plastics, or paper onto which a conductive layer has been formed by applying a conductive material alone or a composition containing a conductive material and a binder resin.

[0157] [1.3] Photosensitive layer The photosensitive layer may contain a charge generating material capable of generating charges and a charge transport material having charge transport properties, and may be composed of, for example, a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material.

[0158] On the other hand, the charge generating material and the charge transporting material may be contained in one layer (charge generating / transporting layer).

[0159] However, if the charge generating layer and the charge transporting layer are constructed separately, the residual potential is less likely to increase when the electrophotographic photosensitive member is used repeatedly, and further, the properties of each layer can be easily controlled depending on the purpose of the electrophotographic photosensitive member.

[0160] Hereinafter, an example in which the charge generating layer and the charge transporting layer are formed separately will be described, but the photosensitive layer of the electrophotographic photoreceptor according to the present invention is not limited to this embodiment.

[0161] (charge generation layer) The charge generating layer may be any layer that can generate charges when irradiated with light, and may be, for example, a layer containing a charge generating substance and a binder resin.

[0162] The charge generating material is not particularly limited, and known charge generating materials can be used.

[0163] Examples include azo pigments such as Sudan Red and Diane Blue; quinone pigments such as pyrenequinone and anthanthrone; quinocyanine pigments; perylene pigments; indigo pigments such as indigo and thioindigo; phthalocyanine pigments such as titanyl phthalocyanine; and the like.

[0164] The charge generating layer may contain only one of these charge generating materials, or may contain two or more of them.

[0165] On the other hand, known resins can also be used as the binder resin.

[0166] Examples thereof include polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenolic resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, polyvinyl carbazole resin, and copolymers thereof (e.g., vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, etc.).

[0167] The charge generating layer may contain only one of these binder resins, or may contain two or more of them.

[0168] The amount of the charge generating material in the charge generating layer is preferably in the range of 1 to 600 parts by mass, more preferably in the range of 50 to 500 parts by mass, per 100 parts by mass of the binder resin. When the amount of the charge generating material is in this range, a sufficient amount of charge can be generated.

[0169] The thickness of the charge generation layer is appropriately selected depending on the characteristics of the charge generation material, the characteristics and mixing ratio of the binder resin, etc., but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.05 to 3 μm. When the thickness of the charge generation layer is in this range, the charge generation ability tends to be stable and the layer can have a sufficiently high strength.

[0170] (charge transport layer) The charge transport layer may be any layer that can transport the charges generated in the charge generation layer, and may be, for example, a layer containing a charge transport substance and a binder resin.

[0171] The charge transport material may be any material capable of transporting charges, and known compounds may be used. Examples of the charge transport material include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, and poly-9-vinylanthracene.

[0172] The charge transport layer may contain only one of these compounds, or may contain two or more of them.

[0173] On the other hand, known resins can also be used as the binder resin.

[0174] Examples include polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, styrene-methacrylate copolymer resin, etc. Among these, polycarbonate resin is preferred, and polycarbonate resin containing a structure such as bisphenol A (BPA), bisphenol Z (BPZ), dimethyl BPA, or BPA-dimethyl BPA copolymer is particularly preferred from the viewpoints of crack resistance, abrasion resistance, and anti-static properties.

[0175] The charge transport layer may contain only one of these compounds, or may contain two or more of them.

[0176] The charge transport layer may contain various additives such as antioxidants and silicone oils, as long as the objects and effects of the present invention are not impaired.

[0177] Specific examples of antioxidants include compounds described in JP-A No. 2000-305291.

[0178] The amount of the charge transport material in the charge transport layer is preferably in the range of 10 to 500 parts by weight, more preferably 20 to 100 parts by weight, per 100 parts by weight of the binder resin. When the amount of the charge transport material is in this range, the charge transport properties of the charge transport layer are improved.

[0179] The thickness of the charge transport layer is preferably in the range of 5 to 40 μm, more preferably in the range of 10 to 30 μm, and is appropriately selected depending on the characteristics of the charge transport material and binder resin, the mixing ratio thereof, etc. When the thickness of the charge transport layer is in this range, the charge transport ability tends to be stable and the layer can have a sufficiently high strength.

[0180] [1.4] Other layers As described above, the photoreceptor may include other layers between the conductive support and the photosensitive layer, if necessary, and may include, for example, the following intermediate layers.

[0181] The intermediate layer is a layer for transferring electrons generated in the charge generating layer to the conductive support side.

[0182] The intermediate layer may be, for example, a layer containing conductive fine particles and a binder resin.

[0183] Examples of conductive fine particles include various metal particles; metal oxide particles such as aluminum oxide, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide; tin-doped indium oxide; antimony-doped tin oxide; and zirconium oxide.

[0184] The intermediate layer may contain only one type of conductive fine particles, or may contain two or more types.

[0185] When the intermediate layer contains two or more kinds of conductive fine particles, these may be in the form of a solid solution or may be fused together.

[0186] The number average primary particle size of the conductive fine particles is preferably 0.3 μm or less, and more preferably 0.1 μm or less.

[0187] The average primary particle size is defined as the average value of 100 primary particle sizes measured directly from an electron microscope image.

[0188] Examples of the binder resin include polyamide resin, casein, polyvinyl alcohol resin, nitrocellulose, ethylene-acrylic acid copolymer, vinyl chloride resin, vinyl acetate resin, polyurethane resin, and gelatin.

[0189] The intermediate layer may contain only one type of binder resin, or may contain two or more types of binder resins.

[0190] The intermediate layer preferably contains 20 to 400 parts by mass, and more preferably 50 to 200 parts by mass, of conductive fine particles per 100 parts by mass of binder resin.

[0191] When the amount of the conductive fine particles is within this range, the layer can have sufficient conductivity.

[0192] The thickness of the intermediate layer is preferably in the range of 0.1 to 15 μm, more preferably in the range of 0.3 to 10 μm. When the thickness of the intermediate layer is within this range, the layer can have a sufficiently high strength.

[0193] [1.5] Manufacturing method of electrophotographic photoreceptor The electrophotographic photoreceptor described above can be manufactured by preparing a conductive support, and carrying out a step of forming a photosensitive layer on the conductive support (photosensitive layer forming step), and a step of forming a surface protective layer on the photosensitive layer (surface protective layer forming step).

[0194] Before forming the photosensitive layer, a step of forming an intermediate layer on the conductive support (intermediate layer forming step) may be carried out.

[0195] The intermediate layer forming step, the photosensitive layer forming step, and the surface protective layer forming step will be described below, but the method for producing the electrophotographic photoreceptor of the present invention is not limited to these methods.

[0196] (Intermediate layer formation process) In the intermediate layer forming step, the above-mentioned conductive support is prepared, and the above-mentioned intermediate layer is formed on the conductive support.

[0197] The intermediate layer can be formed by applying an intermediate layer composition containing the conductive fine particles, the binder resin, and a solvent, and then solidifying the composition.

[0198] Examples of the solvent contained in the intermediate layer composition are alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, and sec-butanol, which are preferred from the viewpoint of the coatability of the intermediate layer composition. Furthermore, from the viewpoint of improving the storage stability of the intermediate layer composition and the dispersibility of the conductive fine particles, the intermediate layer composition may further contain benzyl alcohol, toluene, cyclohexanone, tetrahydrofuran, or the like.

[0199] The method for preparing the intermediate layer composition is not particularly limited.

[0200] For example, the solvent and binder resin may be mixed first, and then the conductive fine particles may be added.

[0201] The conductive fine particles can be dispersed using an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like.

[0202] The method for applying the intermediate layer composition is not particularly limited, and may be a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, a circular amount-controlled coating method, or the like.

[0203] Furthermore, the method for drying the intermediate layer composition can be appropriately selected from known drying methods depending on the type of solvent and the thickness of the film to be formed, and heat drying is particularly preferred.

[0204] (Photosensitive layer formation process) In the photosensitive layer forming step, a photosensitive layer is formed on the conductive support or on the intermediate layer.

[0205] The method for forming the photosensitive layer is appropriately selected depending on the layer structure of the photosensitive layer.

[0206] For example, when the photosensitive layer consists of only one layer of a charge generation / transport layer, a charge generation / transport layer composition containing a charge generation substance, a charge transport substance, a binder resin, a solvent, etc. is prepared, and this is applied to the intermediate layer and solidified to form the photosensitive layer.

[0207] On the other hand, when the photosensitive layer is composed of two layers, a charge generating layer and a charge transporting layer, the layers are formed in order by the following method.

[0208] <Formation of Charge Generation Layer> The method for forming the charge generation layer is not particularly limited, and the charge generation layer can be formed by applying a charge generation layer composition containing the above-mentioned charge generation material, the above-mentioned binder resin, and a solvent onto the above-mentioned conductive support (or onto the intermediate layer if an intermediate layer formation step is performed) and solidifying it.

[0209] Examples of solvents used in the charge generating layer composition include toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine, etc. The charge generating layer composition may contain only one of these or two or more of them.

[0210] The method for preparing the charge generating layer composition may be any method that allows the charge generating material, binder resin, and solvent to be thoroughly mixed.

[0211] For example, the binder resin and the solvent may be mixed together, and then the charge generating material may be added.

[0212] When preparing the charge generating layer composition, a dispersing device such as an ultrasonic disperser, a ball mill, a sand grinder, or a homomixer can be used.

[0213] The method for applying the charge generating layer composition is not particularly limited, and any known method can be used.

[0214] Examples include dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, circular volumetric coating, and the like.

[0215] The method for solidifying the charge generating layer composition is not particularly limited, and the composition may be solidified by removing the solvent by heating or the like, or may be solidified by air drying or the like.

[0216] <Formation of Charge Transport Layer> The method for forming the charge transport layer is not particularly limited, and the charge transport layer can be formed by applying a charge transport layer composition containing the charge transport material, the binder resin, and a solvent, and then solidifying the composition.

[0217] Examples of the solvent include toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, etc. The charge transport layer composition may contain only one of these solvents or two or more of them.

[0218] The method for mixing the charge transport material, binder resin, and solvent is not particularly limited.

[0219] The mixing can be carried out using a known stirring device or the like.

[0220] Furthermore, the method for applying the charge transport layer composition is not particularly limited, and any known method can be used.

[0221] Examples of such methods include dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, circular amount-controlled coating, etc. The method for solidifying the charge transport layer composition is not particularly limited, and may involve, for example, removing the solvent by heating or the like, or may involve natural drying or the like.

[0222] <Surface protective layer formation process> The surface protective layer according to the present invention is formed by irradiating a coating liquid containing at least the polyfunctional polymerizable compound having or not having hole transport properties, a photopolymerization initiator, and, if necessary, the monofunctional polymerizable compound having hole transport properties, a known charge transport material, inorganic particles, and the like with ultraviolet light to cure the coating liquid.

[0223] Specifically, for example, a coating liquid (hereinafter also referred to as "surface protective layer-forming coating liquid") is prepared by adding a polyfunctional polymerizable compound having hole transport properties, a polyfunctional polymerizable compound not having hole transport properties, a photopolymerization initiator, and, if necessary, inorganic particles and other components to a known solvent. Then, this surface protective layer-forming coating liquid is applied to the outer peripheral surface of the charge transport layer to form a coating film, and the coating film is dried and irradiated with ultraviolet light to cure the polyfunctional polymerizable compound and the like in the coating film, thereby forming the surface protective layer.

[0224] In the curing treatment of the surface protective layer, it is preferable that the coating film is irradiated with ultraviolet light to generate radicals, which cause a polymerization reaction of the polyfunctional polymerizable compound, etc., and form crosslinked bonds through inter- and intra-molecular crosslinking reactions, thereby curing the polyfunctional polymerizable compound, thereby forming a crosslinked curable resin.

[0225] The protective layer-forming coating solution is prepared by dissolving or dispersing the above-mentioned components in a solvent. Among the above-mentioned components, the surface-modified metal oxide particles are used by dispersing them in a solvent. Means for dispersing the inorganic particles and charge transport material in the surface protective layer-forming coating solution include, but are not limited to, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, and the like.

[0226] Any solvent can be used to form the surface protective layer as long as it can dissolve or disperse a polyfunctional polymerizable compound with or without hole transport properties, a photopolymerization initiator, a monofunctional polymerizable compound with hole transport properties, a charge transport material, inorganic particles, etc. Examples of the solvent include, but are not limited to, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, dichloromethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

[0227] Examples of methods for applying the protective layer-forming coating liquid include known methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, circular slide hopper method, etc. When producing a drum-shaped photoreceptor, the circular slide hopper method is preferred as a method for applying the protective layer-forming coating liquid to the surface to be coated.

[0228] Coating by the circular slide hopper method can be carried out using a circular slide hopper coater, in which the coating solution is shared across the slide surface of the device, and coating is carried out by the coating solution flowing down in a strip from the end of the slide surface toward the surface to be coated.

[0229] In coating methods using a circular slide hopper coater, the end of the slide surface and the surface to be coated are positioned with a certain gap, allowing coating to be done without damaging the surface to be coated. In the manufacture of photoreceptors, when forming multiple layers with different properties that dissolve in the same solvent, such as the stacking of an intermediate layer, charge generation layer, charge transport layer, and protective layer, the circular slide hopper method is preferred as a coating method for the second and subsequent layers, since the time spent in the solvent is much shorter than in the dip coating method, meaning that the components of the lower layer hardly dissolve into the upper layer and can be applied without dissolving into the coating tank.

[0230] The coating film may be cured without being dried, but it is preferable to carry out the curing treatment after natural drying or heat drying.

[0231] Drying conditions can be appropriately selected depending on the type of solvent, film thickness, etc. The drying temperature is preferably within the range of room temperature (25° C.) to 180° C., and particularly preferably within the range of 80 to 140° C. The drying time is preferably 1 to 200 minutes, and particularly preferably 5 to 100 minutes.

[0232] Any light source that generates ultraviolet light can be used without limitation as the ultraviolet light source, including, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, and a flash (pulse) xenon lamp.

[0233] The irradiation conditions vary depending on the lamp, but for example, the UV irradiation dose is usually 5 to 500 mJ / cm 2 in the range of 5 to 100 mJ / cm 2 The lamp power is preferably in the range of 0.1 to 5 kW, and particularly preferably in the range of 0.5 to 3 kW. The irradiation time to obtain the required amount of ultraviolet light is, for example, preferably 0.1 seconds to 10 minutes, and from the viewpoint of work efficiency, more preferably 0.1 seconds to 5 minutes.

[0234] In the step of forming the protective layer, drying can be carried out before, after, or during ultraviolet irradiation, and the timing of drying can be appropriately selected by combining these.

[0235] [2] Cleaning blade (2.1) Definitions of terms related to cleaning blades The definition of each term will be explained using Figure 3.

[0236] <Contact force> The contact force is a force applied to the surface of the photoreceptor 10 as a result of applying a load to the cleaning blade CL when the cleaning blade CL is brought into contact with the surface of the photoreceptor 10 at the contact portion C.

[0237] <Effective contact angle> The effective contact angle according to the present invention is the angle between the rubber material and the ridgeline on the downstream side of the rotation direction of the image carrier when the rubber material is in a bent position due to the rubber material being pressed against the image carrier, and is the actual angle θ1 between the tip of the cleaning blade CL and the surface of the photosensitive member 10, as shown in Figure 3.

[0238] The cleaning blade CL according to the present invention is characterized in that the effective contact angle is within the range of 8 to 20°.

[0239] The effective contact angle θ1 can be found by calculating the deflection using the cross-sectional shape of the cleaning blade CL and physical properties such as Young's modulus of the material.

[0240] <Rigid body contact angle> The rigid body contact angle is a design value used when the cleaning blade CL is brought into contact with the surface of the photosensitive member.

[0241] The angle θ2 shown in FIG. 3 is the rigid body contact angle formed between the tip of the cleaning blade CL and the surface of the photosensitive member CL when the cleaning blade CL is assumed to be a rigid body (shown by the dotted line).

[0242] <Edge angle> The edge angle is the angle of the ridgeline of the rubber material at the contact point C with the photosensitive member surface, as shown in Fig. 3. The edge angle according to the present invention is characterized by an obtuse angle of 120° or less.

[0243] <Free length> The free length according to the present invention is the length of the portion of the rubber material that protrudes from the metal plate Pg, which is the portion L in FIG. 3 excluding the portion bonded to the metal plate Pg.

[0244] <Upstream wedge angle> The upstream wedge angle is the angle formed between the rubber material and the ridge line on the upstream side in the rotation direction of the photoreceptor 10, as shown in FIG.

[0245] (2.2) Cleaning Blade Overview The electrophotographic image forming system of the present invention includes a step of pressing the edge of a cleaning blade against the surface of the photosensitive member to remove the toner for developing the electrostatic image.

[0246] The cleaning blade has an obtuse edge angle of 120° or less and its tip ridge is pressed against the surface of the photosensitive member, and the effective contact angle of the cleaning blade is within the range of 8 to 20°.

[0247] FIG. 3 is a conceptual side view of the relationship between the cleaning blade according to the present invention and the electrophotographic photosensitive member.

[0248] As shown in Figure 3, the cleaning blade has an edge angle of θ e The tip edge is arranged to abut against the surface of the photosensitive member 10 so that the effective abutment angle θ1 falls within the above range (the portion where the tip edge abuts against the surface of the photosensitive member 10 is referred to as abutment portion C).

[0249] By setting the effective contact angle θ1 to 8° or more, a large wedge space is secured between the photosensitive member and the blade downstream of the edge of the cleaning blade in the rotation direction, and even if aggregates reach the cleaning blade, deposition on the blade edge is suppressed.

[0250] The effective contact angle θ1 of the cleaning blade CL according to the present invention is 8° or more, and is more preferably 9° or more from the viewpoint of achieving the desired effect.

[0251] However, if the effective contact angle is too large, the amount of retraction of the blade edge becomes large, which may result in poor cleaning due to blade curling or increased stick-slip vibration.

[0252] The effective contact angle θ1 of the cleaning blade according to the present invention is 20° or less, and is more preferably 17° or less from the viewpoint of the effectiveness.

[0253] Furthermore, in the present invention, since the edge angle of the cleaning blade is an obtuse angle, the amount of retraction of the edge of the cleaning blade itself is small, and therefore the effective contact angle can be set larger than when the edge angle is not an obtuse angle.

[0254] However, if the edge angle is too large, the surface pressure of the blade edge decreases, making it easier for the external additive to slip through the blade, which may result in the external additive being more likely to accumulate on the blade edge even when the effective contact angle is ensured.

[0255] The edge angle θe of the cleaning blade according to the present invention is an obtuse angle of 120° or less, but is more preferably 95° or more and 110° or less from the viewpoint of achieving the desired effect.

[0256] (2.3) Cleaning Blade Configuration The cleaning blade CL according to the present invention is mainly made of a rubber material.

[0257] The rubber material portions do not all need to be made of the same material, and may be, for example, a two-layer blade consisting of a contact layer that forms the edge portion and a support layer.

[0258] In the case of a two-layer structure, for example, the material of the support layer may have a lower permanent deformation rate than the material of the contact layer in order to prevent settling.

[0259] <Material> The material of the cleaning blade CL according to the present invention is preferably urethane rubber from the viewpoint of wear resistance and moldability.

[0260] <hardness> The rubber hardness of the cleaning blade CL according to the present invention is preferably within the range of 65 to 85° in terms of the hardness value defined by JIS-A.

[0261] If the rubber hardness is 65° or more, the blade is less likely to be retracted, the upstream wedge angle θ3 does not become too small, and the effective contact angle can be set appropriately high, thereby suppressing the accumulation of external additives on the blade edge.

[0262] Furthermore, if the rubber hardness is 85° or less, the rubber part is flexible and will be in a position where it is properly biting into the photosensitive member. This means that even when vibrations are generated during operation, the variation in the longitudinal surface pressure distribution is relatively small, and the accumulation of external additives on the blade edge can be more effectively suppressed.

[0263] <Rebound resilience> The cleaning blade CL according to the present invention preferably has a rebound resilience in the range of 10 to 40°.

[0264] If the resilience is within the above range, vibrations are appropriately suppressed, and the external additive is less likely to slip through the blade.

[0265] <shape> The cleaning blade CL according to the present invention preferably has a free length L in the range of 7.0 to 12.5 mm and a thickness in the range of 1.7 to 2.5 mm.

[0266] Furthermore, the ratio (L / d) of the free length L to the thickness d is preferably 3.5 or more. As mentioned above, the surface pressure at the tip of the cleaning blade is not completely uniform in the longitudinal direction, and there are areas where the surface pressure is locally high and low in the longitudinal direction due to minute vibrations at the tip of the blade that occur when the blade is driven. In areas where the surface pressure is locally low, the external additives in particular tend to slip through the nip portion of the cleaning blade, making it easier for external additives to aggregate at the edge.

[0267] When the ratio of thickness d to free length L is 3.5 or more, the blade rubber portion bends and assumes a contact posture in which the rubber portion bites into the photosensitive member, thereby relatively reducing the variation in longitudinal surface pressure distribution even under conditions in which vibration occurs during operation, and more effectively suppressing the generation of external additive aggregates. From the viewpoint of enhancing the effects of the present invention, the ratio is more preferably 4.5 or more, and particularly preferably 5.0 or more. Furthermore, the upper limit is preferably 6.0 or less. If the ratio is greater than 6.0, the amount of retraction of the tip of the cleaning blade increases, which may make it more likely to turn over.

[0268] It is believed that as long as the ratio (L / d) of free length L to thickness d is within the above range, the effect of suppressing streak-like adhesion can be achieved regardless of the absolute magnitude of each dimension. However, taking into account dimensional variations in parts and the need to design units into compact sizes, the above-mentioned free length range of 7.0 to 12.5 mm and thickness range of 1.7 to 2.5 mm are more realistic.

[0269] <Conditions of Agreement> The contact force of the cleaning blade CL according to the present invention is preferably within the range of 9 to 30 (N / m) from the viewpoint of preventing incomplete wiping and curling.

[0270] If the contact force is 9 (N / m) or more, there is no risk of leaving any areas unwiped, and if it is 30 (N / m) or less, there is no risk of peeling.

[0271] (composition) As mentioned above, the rubber material portions do not need to be made of the same material, and for example, the blade may be made of two layers, consisting of a contact layer that forms the edge portion and a support layer.In the case of a two-layer structure, for example, the support layer may be made of a material with a lower permanent deformation rate than the material of the contact layer in order to reduce durability fluctuations in the contact force.

[0272] [3] Toner for developing electrostatic images The electrostatic image developing toner (also simply referred to as "toner") used in the image forming system of the present invention contains toner particles comprising toner base particles and external additives attached to the surfaces of the toner base particles.

[0273] In particular, it is preferable that the toner particle surface contains at least a fatty acid metal salt as a lubricant as an external additive. The amount of the fatty acid metal salt added is preferably 0.15% by mass or more relative to the toner base particles, from the viewpoint that the surface of the photoreceptor is coated with the fatty acid metal salt, the surface is hydrophobized, and the generation of aggregates can be more effectively suppressed even in the presence of unreacted groups.

[0274] In this specification, the term "toner base particles" refers to particles that form the base of "toner particles."

[0275] The "toner base particles" contain at least a binder resin, and may also contain other components such as a colorant, a release agent (wax), and a charge control agent, as necessary.

[0276] Particles formed by adding and adhering external additives to the surfaces of "toner base particles" are generally called "toner particles."

[0277] However, when the toner base particles themselves are used as they are without adding and adhering an external additive, the toner base particles themselves may also be referred to as "toner particles." The term "toner" refers to an aggregate of "toner particles."

[0278] (3.1) Toner base particles As the toner base particles according to the present invention, known toner base particles can be used.

[0279] Specifically, such toner base particles are composed of toner base particles containing at least a binder resin and, if necessary, a colorant.

[0280] The toner base particles may further contain other components such as a release agent and a charge control agent, if necessary.

[0281] (3.2) Binder resin As the binder resin, known resins can be used, and for example, amorphous resins and crystalline resins can be suitably used.

[0282] In particular, it is preferable that the resin contains a styrene-acrylic resin and a crystalline polyester resin, which will be described later.

[0283] (3.2.1) Amorphous resin The amorphous resin that can be used in the present invention is not particularly limited, but known amorphous resins such as vinyl resins and polyester resins as described below, as well as urethane resins and urea resins can be preferably used.

[0284] <Vinyl resin> When a vinyl resin is used as the amorphous resin, the vinyl resin is not particularly limited as long as it is a polymer of a vinyl compound, and examples thereof include acrylate resin, styrene-acrylate resin, and ethylene-vinyl acetate resin.

[0285] These may be used alone or in combination of two or more.

[0286] Among the above vinyl resins, styrene-acrylic acid ester resin (styrene-acrylic resin) is preferred in consideration of plasticity during thermal fixing.

[0287] Therefore, although detailed description will be omitted, it is preferable to use, as the styrene monomer, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, and p-ethylstyrene; as the (meth)acrylic acid ester monomer, acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and isobutyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, and isobutyl methacrylate. These styrene monomers and (meth)acrylic acid ester monomers can be used alone or in combination of two or more.

[0288] Other monomers may also be polymerized, and examples thereof include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0289] The method for producing the styrene-acrylic resin is not particularly limited, and it can be produced by emulsion polymerization or the like.

[0290] <Polyester resin> When a polyester resin is used as the amorphous resin, the amorphous polyester resin refers to a resin that does not show a clear endothermic peak in differential scanning calorimetry (DSC) among known polyester resins obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyalcohol).

[0291] Specifically, a clear endothermic peak means a peak whose half-width is within 15°C when measured by differential scanning calorimetry (DSC) at a temperature rise rate of 10°C / min.

[0292] Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; aromatic dicarboxylic acids such as maleic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid; aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenylsuccinic acid, n-dodecenylsuccinic acid, and n-octenylsuccinic acid; and divalent or higher carboxylic acids such as trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

[0293] Examples of polyhydric alcohols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20- Examples of the polyol include aliphatic diols such as eicosanediol; bisphenols such as bisphenol A and bisphenol F, and alkylene oxide adducts of bisphenols such as their ethylene oxide adducts and propylene oxide adducts; and trivalent or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine.

[0294] (3.2.2) Crystalline resin The toner base particles according to the present invention may contain a crystalline resin, and for example, the following crystalline polyesters and the crystalline resins described in paragraphs 0043 to 0102 of JP-A No. 2015-011325 can be suitably used.

[0295] In particular, it is preferable from the viewpoint of production that the resin contains a hybrid crystalline polyester resin.

[0296] <Crystalline polyester resin> The crystalline polyester resin is a portion derived from a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyalcohol), and refers to a resin unit that exhibits a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC) of the toner.

[0297] Specifically, a clear endothermic peak means a peak whose half-width is 15°C or less when measured at a heating rate of 10°C / min by differential scanning calorimetry (DSC) as described in the Examples.

[0298] The crystalline polyester resin is not particularly limited as long as it is as defined above.

[0299] For example, the crystalline polyester resin itself may be contained.

[0300] Alternatively, the hybrid resin having a crystalline polyester resin unit may contain a resin having a structure in which other components are copolymerized in a main chain of a crystalline polyester resin unit, or a resin having a structure in which a crystalline polyester resin unit is copolymerized in a main chain made of other components, and a toner containing this resin may exhibit a clear endothermic peak as described above.

[0301] The crystalline polyester resin is produced from a polycarboxylic acid component and a polyhydric alcohol component. In this case, the crystalline polyester resin unit is composed of the polycarboxylic acid component having the carbon number C(acid) and the polyhydric alcohol component having the carbon number C(alcohol). The valences of the polycarboxylic acid component and the polyhydric alcohol component are preferably 2 to 3, and particularly preferably 2.

[0302] The method for forming the crystalline polyester resin is not particularly limited, and the resin can be formed by polycondensing (esterifying) the polycarboxylic acid and polyhydric alcohol using a known esterification catalyst.

[0303] The ratio of the polyhydric alcohol component to the polycarboxylic acid component is preferably such that the equivalent ratio [OH] / [COOH] of the hydroxy group [OH] of the diol component to the carboxy group [COOH] of the dicarboxylic acid component is 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2.

[0304] Examples of catalysts that can be used in producing the crystalline polyester resin include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphorous compounds; phosphoric acid compounds; and amine compounds.

[0305] Specific examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and salts thereof.

[0306] Examples of titanium compounds include titanium alkoxides such as tetra-normal-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolaminate.

[0307] The germanium compound may include germanium dioxide.

[0308] Further, examples of the aluminum compound include oxides such as polyaluminum hydroxide, aluminum alkoxides, etc., and examples include tributylaluminate, etc. These may be used alone or in combination of two or more.

[0309] The polymerization temperature and polymerization time are not particularly limited, and the pressure in the reaction system may be reduced during the polymerization, if necessary.

[0310] Furthermore, in the case of a hybrid resin having a crystalline polyester resin unit, the content of the crystalline polyester resin unit is preferably within a range of 50 to 98% by mass with respect to the total amount of the hybrid resin.

[0311] By setting the content within the above range, sufficient crystallinity can be imparted to the hybrid resin. The constituent components and content ratios of each unit in the hybrid resin can be determined by, for example, NMR measurement or methylation reaction P-GC / MS measurement.

[0312] Here, the hybrid resin contains, in addition to the crystalline polyester resin unit, an amorphous resin unit other than the polyester resin, which will be described in detail below.

[0313] The hybrid resin may be in any form, such as a block copolymer or a graft copolymer, as long as it contains the above-mentioned crystalline polyester resin unit and an amorphous resin unit other than the polyester resin, but is preferably a graft copolymer.

[0314] By forming a graft copolymer, it becomes easier to control the orientation of the crystalline polyester resin units, and sufficient crystallinity can be imparted to the hybrid resin.

[0315] Furthermore, from the above viewpoint, it is preferable that the crystalline polyester resin unit is grafted onto an amorphous resin unit other than the crystalline polyester resin as the main chain.

[0316] That is, the hybrid crystalline polyester resin is preferably a graft copolymer having an amorphous resin unit other than polyester resin as the main chain and a crystalline polyester resin unit as the side chain.

[0317] By adopting the above-mentioned configuration, the orientation of the crystalline polyester resin units can be further enhanced, and the crystallinity of the hybrid resin can be improved.

[0318] The hybrid resin may further contain a substituent such as a sulfonic acid group, a carboxy group, or a urethane group. The substituent may be introduced into a crystalline polyester resin unit or into an amorphous resin unit other than the polyester resin, which will be described in detail below.

[0319] <Amorphous resin unit other than polyester resin> The non-polyester resin amorphous resin unit is a portion derived from an amorphous resin other than the above-mentioned crystalline polyester resin.

[0320] The inclusion of amorphous resin units in hybrid resins (and even in toners) allows the chemical structure to be characterized by selecting an appropriate analytical method from among NMR measurement, P-GC / MS measurement, methylation reaction P-GC / MS measurement, etc., depending on the structure.

[0321] Furthermore, the amorphous resin unit is a resin unit that does not have a melting point and has a relatively high first glass transition point (Tg) when differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight as the unit.

[0322] The amorphous resin unit is not particularly limited as long as it is as defined above.

[0323] For example, with respect to a resin having a structure in which other components are copolymerized into a main chain of an amorphous resin unit, or a resin having a structure in which an amorphous resin unit is copolymerized into a main chain made of other components, if a toner containing this resin has the above-mentioned amorphous resin unit, then the resin corresponds to a hybrid resin having an amorphous resin unit.

[0324] The amorphous resin unit is preferably made of the same type of resin as the amorphous resin contained in the binder resin (that is, the resin other than the hybrid resin).

[0325] By adopting such a form, the affinity between the hybrid resin and the amorphous resin is further improved, the hybrid resin is more easily incorporated into the amorphous resin, and the charging uniformity and the like are further improved.

[0326] Here, "same type of resin" means that characteristic chemical bonds are commonly contained in the repeating units.

[0327] Furthermore, the "characteristic chemical bond" follows the "polymer classification" described in the National Institute for Materials Science (NIMS) Materials Database (http: / / polymer.nims.go.jp / PoLyInfo / guide / jp / term_polymer.html).

[0328] That is, the chemical bonds that make up polymers classified into a total of 22 types, including polyacrylic, polyamide, polyanhydride, polycarbonate, polydiene, polyester, polyhaloolefin, polyimide, polyimine, polyketone, polyolefin, polyether, polyphenylene, polyphosphazene, polysiloxane, polystyrene, polysulfide, polysulfone, polyurethane, polyurea, polyvinyl, and other polymers, are called "characteristic chemical bonds."

[0329] Furthermore, when the resin is a copolymer, "same type of resin" refers to resins that have a characteristic chemical bond in common when the chemical structures of multiple monomer species that make up the copolymer contain monomer species having the above-mentioned chemical bond as constituent units.

[0330] Therefore, even if the properties of the resins themselves are different from each other or the molar ratios of the monomer species that make up the copolymer are different from each other, they are considered to be the same type of resin as long as they have characteristic chemical bonds in common.

[0331] For example, a resin (or resin unit) formed from styrene, butyl acrylate, and acrylic acid and a resin (or resin unit) formed from styrene, butyl acrylate, and methacrylic acid have at least chemical bonds that constitute polyacrylic, and therefore are the same type of resin.

[0332] For example, a resin (or resin unit) formed from styrene, butyl acrylate, and acrylic acid and a resin (or resin unit) formed from styrene, butyl acrylate, acrylic acid, terephthalic acid, and fumaric acid have at least a chemical bond that constitutes polyacrylic as a common chemical bond.

[0333] Therefore, they are the same type of resin.

[0334] The resin component constituting the amorphous resin unit is not particularly limited, but examples thereof include a vinyl resin unit, a urethane resin unit, and a urea resin unit.

[0335] Among these, vinyl resin units are preferred because their thermoplasticity can be easily controlled.

[0336] The vinyl resin unit is not particularly limited as long as it is a polymer of a vinyl compound, and examples thereof include an acrylate resin unit, a styrene-acrylate resin unit, and an ethylene-vinyl acetate resin unit.

[0337] These may be used alone or in combination of two or more.

[0338] The method for forming the styrene-acrylic resin unit is not particularly limited, and examples thereof include a method in which a monomer is polymerized using a known oil-soluble or water-soluble polymerization initiator.

[0339] Specific examples of oil-soluble polymerization initiators include the azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators shown below.

[0340] Examples of the azo or diazo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[0341] Examples of the peroxide polymerization initiator include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, and tris-(t-butylperoxy)triazine.

[0342] When resin particles are formed by emulsion polymerization, a water-soluble radical polymerization initiator can be used, such as persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

[0343] The content of the amorphous resin unit is preferably within a range of 3 to 50% by mass relative to the total amount of the hybrid resin. Furthermore, the content is more preferably within a range of 5 to 30% by mass. By setting the content within this range, sufficient crystallinity can be imparted to the hybrid resin.

[0344] <Method for producing hybrid crystalline polyester resin (hybrid resin)> The method for producing the hybrid resin contained in the binder resin according to the present invention is not particularly limited as long as it is a method capable of forming a polymer having a structure in which the crystalline polyester resin unit and the amorphous resin unit are molecularly bonded.

[0345] Specific examples of methods for producing the hybrid resin include the following methods.

[0346] (1) A method for producing a hybrid resin by polymerizing an amorphous resin unit in advance and then carrying out a polymerization reaction to form a crystalline polyester resin unit in the presence of the amorphous resin unit. In this method, first, the monomers constituting the above-mentioned amorphous resin unit (preferably a vinyl monomer such as a styrene monomer and a (meth)acrylic acid ester monomer) are subjected to an addition reaction to form the amorphous resin unit.

[0347] Next, in the presence of the amorphous resin unit, the polycarboxylic acid and the polyhydric alcohol are polymerized to form a crystalline polyester resin unit.

[0348] In this case, a hybrid resin is formed by condensation reaction of a polycarboxylic acid with a polyhydric alcohol and addition reaction of the polycarboxylic acid or polyhydric alcohol with the amorphous resin unit.

[0349] In the above method, it is preferable to incorporate a site in the crystalline polyester resin unit or the amorphous resin unit that allows these units to react with each other.

[0350] Specifically, when forming the amorphous resin unit, in addition to the monomer that constitutes the amorphous resin unit, a compound having a site that can react with the carboxy group [—COOH] or hydroxy group [—OH] remaining in the crystalline polyester resin unit and a site that can react with the amorphous resin unit is also used.

[0351] That is, this compound reacts with a carboxy group [—COOH] or a hydroxy group [—OH] in the crystalline polyester resin unit, thereby allowing the crystalline polyester resin unit to chemically bond with the amorphous resin unit.

[0352] Alternatively, a compound may be used which is capable of reacting with a polyhydric alcohol or a polycarboxylic acid when forming the crystalline polyester resin unit and which has a site capable of reacting with the amorphous resin unit.

[0353] By using the above method, a hybrid resin having a structure (graft structure) in which a crystalline polyester resin unit is molecularly bonded to an amorphous resin unit can be formed.

[0354] (2) A method in which a crystalline polyester resin unit and an amorphous resin unit are formed separately and then bonded to produce a hybrid resin. In this method, first, a polycarboxylic acid and a polyhydric alcohol are subjected to a condensation reaction to form a crystalline polyester resin unit.

[0355] Separately from the reaction system for forming the crystalline polyester resin unit, the monomers constituting the above-mentioned amorphous resin unit are addition polymerized to form the amorphous resin unit.

[0356] In this case, it is preferable to incorporate a site where the crystalline polyester resin unit and the amorphous resin unit can react with each other.

[0357] The method for incorporating such a reactive site is as described above, and therefore a detailed description thereof will be omitted.

[0358] Next, the crystalline polyester unit formed above is reacted with an amorphous resin unit to form a hybrid resin having a structure in which the crystalline polyester resin unit and the amorphous resin unit are molecularly bonded.

[0359] Furthermore, when the reactive moiety is not incorporated into the crystalline polyester resin unit and the amorphous resin unit, a method may be employed in which a system in which the crystalline polyester resin unit and the amorphous resin unit coexist is formed, and a compound having a moiety capable of bonding to the crystalline polyester resin unit and the amorphous resin unit is added to the system.

[0360] Then, a hybrid resin having a structure in which a crystalline polyester resin unit and an amorphous resin unit are molecularly bonded via the compound can be formed.

[0361] (3) A method of producing a hybrid resin by forming a crystalline polyester resin unit in advance and then carrying out a polymerization reaction to form an amorphous resin unit in the presence of the crystalline polyester resin unit. In this method, first, a polycarboxylic acid and a polyhydric alcohol are polymerized by condensation reaction to form a crystalline polyester resin unit.

[0362] Next, the monomers constituting the amorphous resin units are polymerized in the presence of the crystalline polyester resin units to form the amorphous resin units.

[0363] In this case, similarly to the above (1), it is preferable to incorporate a site in the crystalline polyester resin unit or the amorphous resin unit that allows these units to react with each other.

[0364] The method for incorporating such a reactive site is as described above, and therefore a detailed description thereof will be omitted.

[0365] By using the above method, a hybrid resin having a structure (graft structure) in which an amorphous resin unit is molecularly bonded to a crystalline polyester resin unit can be formed.

[0366] Among the above formation methods (1) to (3), method (1) is preferred because it is easy to form a hybrid resin having a structure in which crystalline polyester resin chains are grafted onto amorphous resin chains and because it simplifies the production process.

[0367] The method (1) is preferred because the amorphous resin units are formed first and then the crystalline polyester resin units are bonded to the amorphous resin units, which tends to result in uniform orientation of the crystalline polyester resin units, and therefore makes it possible to reliably form the hybrid resin suitable for the toner defined in the present invention.

[0368] (3.3) Colorants As the colorant that can constitute the toner base particles, carbon black, magnetic materials, dyes, pigments, etc. can be used arbitrarily. As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, etc. can be used.

[0369] As magnetic materials, ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, ferromagnetic metal compounds such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but become ferromagnetic when heat treated, such as alloys called Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide can be used.

[0370] Examples of magenta or red colorants include CI Pigment Red 2, 3, 5, 6, 7, 15, 16, 48:1, 48:3, 53:1, 57:1, 60, 63, 64, 68, 81, 81:4, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, and 269.

[0371] Examples of colorants for orange or yellow include CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Yellow 12, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 83, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 138, CI Pigment Yellow 139, CI Pigment Yellow 155, CI Pigment Yellow 162, CI Pigment Yellow 180, CI Pigment Yellow 185, and CI Solvent Yellow 93.

[0372] Furthermore, examples of colorants for green or cyan include CI Pigment Blue 2, 3, 15, 15:2, 15:3, 15:4, 16, 17, 60, 62, 66, and CI Pigment Green 7.

[0373] These colorants can be used alone or in combination of two or more, as required.

[0374] The amount of colorant added is preferably within a range of 1 to 30% by mass, more preferably within a range of 2 to 20% by mass, based on the total amount of toner base particles, and a mixture thereof can also be used.

[0375] Within this range, color reproducibility of the image can be ensured.

[0376] The dispersion diameter of the colorant in the toner is preferably in the range of 10 to 1000 nm, more preferably in the range of 50 to 500 nm, and even more preferably in the range of 80 to 300 nm, in terms of volume average particle diameter.

[0377] (3.4) Release agent The release agent constituting the toner base particles is not particularly limited, and known release agents can be used.

[0378] Specific examples include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, ester waxes such as behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellitate tristearyl, and distearyl maleate, and amide waxes such as ethylenediamine behenylamide and trimellitate tristearylamide.

[0379] The melting point of the release agent is preferably within a range of 40 to 160°C, and more preferably within a range of 50 to 120°C.

[0380] By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and even when fixing is performed at a low temperature, stable toner image formation can be achieved without causing cold offset or the like.

[0381] The content of the release agent in the toner base particles is preferably in the range of 1 to 30% by mass, and more preferably in the range of 5 to 20% by mass.

[0382] (3.5) Charge control agent Furthermore, a charge control agent can be added to the toner base particles according to the present invention, if necessary.

[0383] As the charge control agent, various known agents can be used.

[0384] As the charge control agent, various known compounds that can be dispersed in an aqueous medium can be used, and specific examples thereof include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, metal salicylate salts or metal complexes thereof, and the like.

[0385] The content of the charge control agent is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.5 to 5% by mass, based on the total amount of the binder resin.

[0386] (3.6) External additives The toner particles constituting the electrostatic image developing toner according to the present invention preferably contain at least a fatty acid metal salt as an external additive. Further, from the viewpoint of improving the charging performance, fluidity or cleaning property of the toner, known inorganic particles, organic particles or lubricant particles may be added as external additives to the surface of the toner base particles.

[0387] The amount of the fatty acid metal salt added is preferably within a range of 0.15 to 0.30% by mass relative to the toner base particles, from the viewpoint of sufficiently improving the lubricity of the surface.

[0388] If the amount of the fatty acid metal salt added is within the range of 0.15 to 0.30% by mass relative to the toner base particles, the spreading effect is sufficient, but the coverage rate of the fatty acid metal salt does not decrease, and the surface lubricity can be sufficiently improved.

[0389] The fatty acid metal salt is preferably zinc stearate from the viewpoint of improving surface lubricity. Furthermore, the spacing of the layered crystals determined by the alkyl chain length becomes appropriate, and the cleavage and spreadability are good, thereby further improving the surface lubricity.

[0390] If the particle size of the fatty acid metal salt is small, it can be applied more uniformly and the lubricity of the surface can be improved.

[0391] From the above viewpoint, the particle size is preferably 4 μm or less, more preferably 2 μm or less. Because the particle size of the fatty acid metal salt is small as described above, it can be applied uniformly and the lubricity of the surface can be improved.

[0392] In addition, fatty acid metal salts having a large particle size of 10 μm or more may be used in combination with fatty acid metal salts having a small particle size.

[0393] Since fatty acid metal salts with large particle diameters are more likely to separate from the toner base particles, the total amount of fatty acid metal salts supplied to the photoreceptor can be increased.

[0394] As the inorganic fine particles, inorganic fine particles such as silica, titania, alumina, and strontium titanate are preferred.

[0395] In particular, from the viewpoint of stress resistance, it is preferable to add large particle size silica having a number average primary particle size in the range of about 80 to 500 nm.

[0396] If necessary, these inorganic fine particles may be subjected to a hydrophobic treatment.

[0397] As the organic fine particles, spherical organic fine particles having a number average primary particle size in the range of about 10 to 2000 nm can be used.

[0398] Specifically, organic fine particles made of homopolymers such as styrene and methyl methacrylate, or copolymers thereof can be used.

[0399] Lubricants are used to further improve cleaning properties and transfer properties, particularly to obtain the effects of the present invention. Examples of lubricants include metal salts of higher fatty acids such as salts of stearic acid with zinc, aluminum, copper, magnesium, calcium, etc., salts of oleic acid with zinc, manganese, iron, copper, magnesium, etc., salts of palmitic acid with zinc, copper, magnesium, etc., salts of linoleic acid with zinc, calcium, etc., and salts of ricinoleic acid with zinc, calcium, etc.

[0400] The amount of the external additive added is preferably within a range of 0.1 to 10.0% by mass relative to 100% by mass of the toner base particles.

[0401] [4] Image forming device The image forming apparatus used in the electrophotographic image forming system of the present invention is preferably an image forming apparatus using a general electrophotographic method, and preferably includes at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, and a cleaning unit.

[0402] In particular, it is preferable that the image forming apparatus used is a tandem type image forming apparatus.

[0403] FIG. 4 is an explanatory cross-sectional view showing an example of the configuration of an image forming apparatus according to the present invention, and FIG. 5 is an explanatory cross-sectional view showing an example of the configuration of a main part of the image forming apparatus.

[0404] As shown in FIG. 4, this image forming apparatus 100 is called a tandem color image forming apparatus, and has four sets of image forming units 110Y, 110M, 110C, and 110Bk, paper feeding and conveying means 150, and fixing means 170.

[0405] An original image reading device SC is disposed on the upper part of the main body of the image forming apparatus 100.

[0406] The image forming units 110Y, 110M, 110C, and 110Bk are arranged side by side in the vertical direction.

[0407] The image forming units 110Y, 110M, 110C, and 110Bk each include a rotating drum-shaped photosensitive member 111Y, 111M, 111C, and 111Bk, and, arranged sequentially in the direction of rotation of the photosensitive member on the outer circumferential surface area thereof, a lubricant supply means, a charging means 113Y, 113M, 113C, and 113Bk, an exposure means 115Y, 115M, 115C, and 115Bk, a developing means 117Y, 117M, 117C, and 117Bk, a primary transfer roller (primary transfer means) 133Y, 133M, 133C, and 133Bk, a cleaning means 119Y, 119M, 119C, and 119Bk, and a lubricant removal means.

[0408] Then, toner images of yellow (Y), magenta (M), cyan (C) and black (Bk) are formed on the photoreceptors 111Y, 111M, 111C and 111Bk, respectively.

[0409] Image forming units 110Y, 110M, 110C, and 110Bk are configured similarly except for the colors of the toner images formed on photoreceptors 111Y, 111M, 111C, and 111Bk, and therefore will be described below using image forming unit 110Y as an example.

[0410] The electrophotographic photosensitive member, charging means, exposure means, developing means, transfer means, fixing means and cleaning means will be explained in this order.

[0411] (4.1) Charging means As shown in FIG. 4, the charging unit 113Y is a unit that charges the surface of the photosensitive member 111Y with a charging roller.

[0412] The charging means 113Y in this example comprises a charging roller disposed in contact with the surface of the photosensitive member 111Y, and a power source for applying a voltage to the charging roller.

[0413] In the present invention, the charging means is of a proximity charging type, in which a charging roller is brought into contact with or in proximity to the surface of the photosensitive member and charged. In the charging roller 113 as described above, a charging bias voltage is applied to the core of the charging roller 113 from a power source, whereby the surface of the photosensitive member 111Y is charged to a predetermined potential of a predetermined polarity.

[0414] Here, the charging bias voltage may be, for example, only a DC voltage, but it is preferable to use an oscillating voltage in which an AC voltage is superimposed on a DC voltage, as this provides excellent charging uniformity.

[0415] The charging bias voltage can be set within the range of, for example, about −2.5 to −1.5 kV.

[0416] An example of the charging conditions for the charging roller 113Y shown in FIG. 4 is that the charging bias voltage is formed by a DC voltage of −500 V and an AC voltage that is a sine wave with a frequency of 1000 Hz and a peak-to-peak voltage of 1300 V. When this charging bias voltage is applied, the surface of the photosensitive member is uniformly charged to −500 V.

[0417] (5.2) Exposure means As shown in FIG. 4, the exposure means 115Y is a means for exposing the surface of the photosensitive member 111Y, which has been given a uniform potential by the charging means 113Y, based on an image signal (yellow image signal), to form an electrostatic latent image corresponding to the yellow image.

[0418] The exposure means 115Y is composed of an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive member 111Y and an imaging element, or a laser optical system or the like is used.

[0419] (5.3) Developing means As shown in FIG. 4, the developing means (developing machine) 117Y is a means for supplying toner to the surface of the photoreceptor 111Y, developing the electrostatic latent image formed on the surface of the photoreceptor 111Y, and forming a toner image.

[0420] Specifically, the developing means 117Y in this example is composed of a developing roller 118Y that has a built-in magnet and rotates while holding developer, and a voltage application device (not shown) that applies DC and / or AC bias voltage between the photosensitive element 111Y and the developing roller 118Y.

[0421] The developing means 117Y is preferably disposed at the most downstream position in the rotation direction of the photosensitive member, since toner filming is likely to occur at the most downstream position.

[0422] The rotation of the developing roller 118Y transports the toner to the photoreceptor 111Y.

[0423] Then, the thin layer of toner on the developing roller 118Y comes into contact with the photosensitive member 111Y and develops the electrostatic latent image on the photosensitive member 111Y.

[0424] The developing roller 118Y is connected to a voltage application device.

[0425] Then, a DC and / or AC bias voltage is applied to the developing roller 118Y by this voltage application device.

[0426] By controlling the voltage applied to the developing roller 118Y, the developing potential (also called developing bias) (Vdc) can be adjusted to a desired value.

[0427] Due to the potential difference (development potential difference) between the potential of the electrostatic latent image carried by the developing roller 118Y and the photosensitive member 111Y, an electric field is formed in the developing section where the developing roller 118Y and the photosensitive member 111Y face each other.

[0428] The toner in the developer transported to the developing unit by the rotation of the developing roller 118Y moves due to the force of the electric field and is attracted to the electrostatic latent image on the photoreceptor 111Y. When the electrostatic latent image carried on the photoreceptor 111Y is visualized, a toner image corresponding to the shape of the electrostatic latent image is formed on the surface of the photoreceptor 111Y.

[0429] Here, the electrostatic latent image on the photosensitive member includes a non-image portion and an image portion.

[0430] The non-image portion is a portion of the surface of the photosensitive member 111Y that is uniformly charged by the charging roller 113Y, and the non-image portion potential (V0) is the potential of this non-image portion.

[0431] The image area is a portion of the surface of the photoconductor 111Y where the potential has decreased due to exposure of a part of the non-image area by the exposure means, and the image area potential (Vi) is the potential of this image area.

[0432] Furthermore, the development potential (Vdc) is set to a value between the non-image portion potential (V0) and the image portion potential (Vi).

[0433] In the non-image area, an electric field is formed in a direction that moves the toner from the photosensitive member toward the developing means.

[0434] In the image area, an electric field is formed in a direction that moves the toner from the developing means side toward the photosensitive member.

[0435] In the present invention, the development conditions of the developing machine under a normal temperature and humidity environment of 23°C and 50% RH are set to one of the following conditions (i) to (iii) compared to a low temperature and low humidity environment of 10°C and 20% RH.

[0436] (i) Decrease the AC duty ratio (the ratio of the negative side width (time) T(-) of the AC in the cycle T) of the development potential applied to the development roller of the developing machine. (ii) Decreasing the concentration of the toner for the two-component developer in the two-component developer (iii) Increase the fogging margin (potential V0 of the non-image area of ​​the photoconductor minus development potential Vdc)

[0437] Therefore, for example, when condition (i) is set, the voltage application device of the developing means applies a voltage so as to lower the AC duty ratio of the AC and DC superimposed on the developing roller.

[0438] In addition, when the condition (iii) is set, the Vc applied to the core of the charging roller is Set the absolute value high.

[0439] Furthermore, when the condition (ii) is set, the two-component developer used is a developer with a low toner concentration.

[0440] (5.4) Transfer means As shown in FIG. 4, a primary transfer roller 133Y constituting a transfer means is a means for transferring a toner image formed on a photosensitive member 111Y onto an intermediate transfer member 131 in the form of an endless belt.

[0441] The primary transfer roller 133Y is disposed in contact with the intermediate transfer body 131.

[0442] In this image forming apparatus 100, an intermediate transfer method is adopted in which toner images formed on photosensitive bodies 111Y, 111M, 111C, and 111Bk are transferred to intermediate transfer body 131 by primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk, and each toner image transferred onto intermediate transfer body 131 is transferred to transfer material P by secondary transfer roller (secondary transfer means) 217, but a direct transfer method may also be adopted in which toner images formed on the photosensitive bodies are transferred directly to the transfer material by transfer means.

[0443] (5.5) Cleaning means As shown in FIG. 4, the cleaning means 119Y is a means for removing toner remaining on the surface of the photoreceptor 111Y.

[0444] The cleaning means 119Y in this example is composed of a cleaning blade, a collection screw, and a housing.

[0445] The details of the cleaning blade according to the present invention used as the cleaning means are as described above, and will be explained here with reference to FIG.

[0446] Toner that is not transferred onto intermediate transfer body 131 in the transfer area and remains on photoconductor 111Y is transported to cleaning unit 119Y, where it is scraped off by cleaning blade 119a and collected by collection screw 119b. Collection screw 119b rotates in one direction and transports the toner that has been scraped off by cleaning blade 119a and fallen to a waste toner box (not shown).

[0447] The cleaning blade is disposed so that its tip faces in the opposite direction (counter direction) to the rotation direction of the photoreceptor 111Y at the contact portion with the surface of the photoreceptor 111Y.

[0448] As shown in FIG. 4, the intermediate transfer body 131 is wound around a plurality of rollers 137A, 137B, 137C, and 137D and is rotatably supported.

[0449] Above the intermediate transfer body 131, a cleaning means 135 is disposed to remove toner remaining on the intermediate transfer body.

[0450] In this image forming apparatus 100, the photosensitive member 111Y, developing means 117Y, cleaning means 119Y, etc. may be integrally combined and may be a process cartridge (image forming unit) configured to be detachably attached to the main body of the apparatus.

[0451] Alternatively, it may be a process cartridge (image forming unit) in which the photosensitive member 111Y is integrally configured with one or more members selected from the group consisting of the charging means 113Y, the exposure means 115Y, the developing means 117Y, the primary transfer roller 133Y, and the cleaning means 119Y.

[0452] The process cartridge 200 has a housing 201, and a photosensitive member 111Y, a charging unit 113Y, a developing unit 117Y, a cleaning unit 119Y, and a primary transfer roller 133Y housed therein.

[0453] The apparatus main body is also provided with support rails 203L and 203R as means for guiding the process cartridge 200 into the apparatus main body. This allows the process cartridge 200 to be detachably mounted to the main body of the apparatus.

[0454] These process cartridges 200 can serve as a single image forming unit that is detachably mounted on the main body of the apparatus.

[0455] The paper feed conveying means 150 is provided so as to be able to convey the transfer material P in the paper feed cassette 211 to the secondary transfer roller 217 via a plurality of intermediate rollers 213A, 213B, 213C, 213D and a registration roller 215.

[0456] The fixing means 170 fixes the color image transferred by the secondary transfer roller 217. The paper discharge rollers 219 are provided so as to be able to place the transfer material P on a paper discharge tray 221 while nipping the transfer material P that has been subjected to the fixing process.

[0457] In the image forming apparatus 100 configured as above, toner images are formed by the image forming units 110Y, 110M, 110C, and 110Bk. Specifically, first, the surfaces of the photoconductors 111Y, 111M, 111C, and 111Bk are discharged and negatively charged by the charging means 113Y, 113M, 113C, and 113Bk.

[0458] Next, the surfaces of the photosensitive members 111Y, 111M, 111C, and 111Bk are exposed to light by exposure means 115Y, 115M, 115C, and 115Bk based on image signals, thereby forming electrostatic latent images.

[0459] Next, developing means 117Y, 117M, 117C, and 117Bk apply toner to the surfaces of the photoreceptors 111Y, 111M, 111C, and 111Bk to develop the toner images.

[0460] Next, primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk are brought into contact with the intermediate transfer body 131 which is rotating.

[0461] As a result, the toner images of each color formed on the photosensitive members 111Y, 111M, 111C, and 111Bk are transferred successively onto the rotating intermediate transfer member 131, thereby transferring a color image (primary transfer).

[0462] During the image forming process, the primary transfer roller 133Bk is always in contact with the photosensitive member 111Bk.

[0463] On the other hand, the other primary transfer rollers 133Y, 133M, and 133C come into contact with the corresponding photoconductors 111Y, 111M, and 111C only during color image formation.

[0464] Then, after the primary transfer rollers 133Y, 133M, 133C, and 133Bk are separated from the intermediate transfer body 131, the toner remaining on the surfaces of the photosensitive bodies 111Y, 111M, 111C, and 111Bk is removed by cleaning means 119Y, 119M, 119C, and 119Bk.

[0465] Next, the surfaces of the photoconductors 111Y, 111M, 111C, and 111Bk are neutralized by neutralizing means (not shown) as necessary, and then negatively charged by charging means 113Y, 113M, 113C, and 113Bk.

[0466] Meanwhile, a transfer material P (a support material carrying the final image, such as plain paper or a transparent sheet) contained in a paper feed cassette 211 is fed by a paper feed conveying means 150 and conveyed to a secondary transfer roller (secondary transfer means) 217 ​​via multiple intermediate rollers 213A, 213B, 213C, 213D and a resist roller 215.

[0467] Then, the secondary transfer roller 217 is brought into contact with the rotating intermediate transfer body 131, and the color images are transferred onto the transfer material P all at once (secondary transfer).

[0468] The secondary transfer roller 217 comes into contact with the intermediate transfer body 131 only when performing secondary transfer onto the transfer material P. After that, the transfer material P onto which the color image has been collectively transferred is separated at a portion of the intermediate transfer body 131 where the curvature is high.

[0469] The transfer material P onto which the color images have been transferred all at once in this way is subjected to a fixing process by fixing means 170, and then is nipped by paper discharge rollers 219 and placed on a paper discharge tray 221 outside the apparatus.

[0470] After the transfer material P onto which the color image has been collectively transferred is separated from the intermediate transfer body 131, the cleaning means 135 removes the remaining toner on the intermediate transfer body 131. [Example]

[0471] Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these. In the examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified.

[0472] [Preparation of an electrophotographic image forming system: indicated as "system" in the table.] [Preparation of Electrophotographic Photoreceptor 1: Hereinafter referred to as "Photoreceptor 1"] An electrophotographic photoreceptor 1 was prepared as follows.

[0473] <Preparation of conductive support> The surface of a cylindrical aluminum support having a diameter of 30 mm was machined to prepare a conductive support having a surface roughness Rz=1.5 (μm).

[0474] <Formation of the intermediate layer> The following components were dispersed batchwise using a sand mill for 10 hours to obtain a dispersion.

[0475] (composition) Binder resin: Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part by mass Conductive particles: Titanium oxide SMT500SAS (manufactured by Teika Co., Ltd.) 3 parts by mass Methanol 10 parts by mass

[0476] Thereafter, the dispersion was diluted two-fold with methanol and allowed to stand overnight.

[0477] After being left to stand, the dispersion was filtered (using a filter: Rigimesh 5 μm filter manufactured by Nippon Pall Corporation) to obtain an intermediate layer composition.

[0478] The intermediate layer composition was applied onto the conductive support by dip coating and then solidified.

[0479] The dry thickness of the intermediate layer was 2 μm.

[0480] <Formation of Charge Generation Layer> The following components were mixed and dispersed for 10 hours using a sand mill to prepare a charge generating layer composition.

[0481] (composition) Charge-generating material: titanyl phthalocyanine pigment (a titanyl phthalocyanine pigment having a maximum diffraction peak at at least 27.3° in Cu-Kα characteristic X-ray diffraction spectrum measurement) 20 parts by mass Binder resin: Polyvinyl butyral resin (#6000-C: manufactured by Denki Kagaku Kogyo Co., Ltd.) 10 parts by mass t-Butyl acetate 700 parts by mass 4-Methoxy-4-methyl-2-pentanone 300 parts by mass

[0482] The charge generating layer composition was applied onto the intermediate layer by dip coating and then solidified.

[0483] The dry thickness of the charge generating layer (also referred to as "dry film thickness") was 0.3 μm.

[0484] <Formation of charge transport layer> The following components were mixed to prepare a charge transport layer composition.

[0485] (composition) Charge transport material: CTM "Compound X below" (150 parts by mass Binder resin: Polycarbonate (Z-300, manufactured by Mitsubishi Gas Chemical Company, Inc.) 300 parts by mass Antioxidant: Irganox 1010 (BASF Japan) 6 parts by mass Tetrahydrofuran 1600 parts by mass Toluene 400 parts by mass Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 1 part by mass

[0486] The charge transport layer composition was applied onto the charge generation layer by dip coating and allowed to solidify.

[0487] The dry thickness of the charge transport layer was 25 μm.

[0488] [ka]

[0489] <Formation of surface protection layer> The following components were mixed to prepare a surface protective layer composition.

[0490] (composition) Silicon oxide (silicon oxide with a number average primary particle size of 30 nm, surface-modified (surface-treated) with the same mass of methylhydrogenpolysiloxane) 30 parts by mass Hole transporting compound: 150 parts by mass (50% by mass) of the following exemplary compound A1 Polyfunctional polymerizable compound not having hole transport properties: Trimethylolpropane trimethacrylate 105 parts by mass Solvent: 450 parts by weight of isopropyl alcohol Tetrahydrofuran 150 parts by mass The above components were dispersed using a sand mill for 10 hours, and then 15 parts by mass of polymerization initiator [1] (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: "Irgacure 819" (BASF Japan)) was added, and the mixture was mixed and stirred in a dark place to dissolve the components, thereby preparing a surface protective layer coating solution (protect from light during storage). The coating solution was applied to a photoreceptor on which the charge transport layer had been previously formed, using a circular slide hopper coater, to form a surface protective layer. After coating, the photoreceptor was dried at room temperature for 20 minutes (solvent drying step), and then the photoreceptor was rotated at a position 100 mm from a metal halide lamp (500 W) at a cumulative light irradiation energy of 1.9 [J / cm2]. 2 (ultraviolet curing step), a surface protective layer with a thickness of 3 μm was obtained.

[0491] The composition of the coating liquid is also shown in terms of mass % of the hole transport compound when the total solid content is taken as 100 mass %.

[0492] In the examples, the following compounds represented by A1 to A4 were used as hole-transporting compounds. Compounds A1 to A3 were synthesized by the synthetic route for compounds having structures represented by the above general formulas A1 to A3. Compound A4 is a hole-transporting compound of a comparative example.

[0493] [ka]

[0494] [Preparation of Photoreceptors 2 to 5] Photoreceptors 2 to 5 were prepared in the same manner as in the preparation of photoreceptor 1, except that the amount of hole transport compound A1 added to the surface protective layer was changed to 25, 30, 70, and 75 parts by mass.

[0495] [Fabrication of Photoreceptors 6 to 8] Photoreceptors 6 to 8 were prepared in the same manner as in the preparation of photoreceptor 1, except that the hole transport compound A1 introduced into the surface protective layer was changed to hole transport compounds A2 to A4 in the amounts added as shown in the table.

[0496] [Cleaning blade manufacturing] <Preparation of rubber sheet> Using 4,4'-diphenylmethane diisocyanate, polyester polyol, and short-chain polyol as raw materials, a 2 mm thick urethane rubber sheet was produced by a known centrifugal molding method.

[0497] While changing the compounding ratio, rubber sheets with a hardness of 72° and a rebound resilience of 11° were produced.

[0498] The above rubber hardness is a hardness value specified in JIS-A.

[0499] <Edge formation> The rubber sheet A was cut with a blade at an angle of 10° to the vertical direction to form an edge portion with an edge angle of 100°.

[0500] <Cutting and gluing of cleaning blades> The blade was then cut vertically to a size of 340 mm x 14.0 mm. A thermosetting adhesive was used to heat bond the blade to a metal plate with a 4 mm adhesive margin, producing cleaning blade a with a free length of 10.0 mm and a ratio of free length L to thickness d (L / d) of 5.0.

[0501] [Fabrication of cleaning blades b to f, k, and l] Cleaning blades b to f, k and l shown in Tables II and III were prepared in the same manner as cleaning blade a, except that the edge angle was changed to 93°, 96°, 110°, 115°, 120°, 90° and 125°. [Fabrication of cleaning blades g, h, and i] In the preparation of cleaning blade a, the thickness and free length of the rubber sheet were adjusted as shown in Table I to prepare cleaning blades g, h and l.

[0502] [Table 1]

[0503] [Toner manufacturing] <Synthesis of hybrid crystalline polyester resin (c1)> The raw material monomers for the following addition polymerization resin (styrene-acrylic resin: StAc) unit containing a bireactive monomer and a radical polymerization initiator were placed in a dropping funnel.

[0504] Styrene 34 parts by mass n-Butyl acrylate 12 parts by mass Acrylic acid 2 parts by mass Polymerization initiator: di-t-butyl peroxide 7 parts by mass

[0505] Furthermore, the raw material monomers for the polycondensation resin (crystalline polyester resin: CPEs) unit shown below were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve.

[0506] Sebacic acid 369 parts by mass 1,10-Decanediol 318 parts by mass

[0507] Next, raw material monomers for the addition polymerization resin (StAc) were added dropwise over 90 minutes while stirring, and after aging for 60 minutes, unreacted addition polymerization monomers were removed under reduced pressure (8 kPa).

[0508] The amount of the monomer removed at this time was extremely small compared to the ratio of the raw material monomers of the resin.

[0509] Thereafter, 0.8 parts by mass of Ti(OBu)4 was added as an esterification catalyst, the temperature was raised to 235°C, and the reaction was carried out at normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour.

[0510] Next, after cooling to 200° C., the mixture was reacted under reduced pressure (20 kPa) for 1 hour to obtain a hybrid crystalline polyester resin (c1).

[0511] The hybrid crystalline polyester resin (c1) contained 8 mass % of resin (StAc) units other than CPEs (crystalline polyester resin) relative to the total mass of the hybrid crystalline polyester resin (c1), and was a resin in which CPEs were grafted to StAc.

[0512] The hybrid crystalline polyester resin (c1) had a number average molecular weight (Mn) of 9000 and a melting point (Tc) of 76°C.

[0513] <Preparation of Aqueous Dispersion of Hybrid Crystalline Polyester Resin Particles (C1)> 30 parts by mass of the crystalline polyester resin was melted and transferred in the molten state to an emulsifying and dispersing machine "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) at a transfer rate of 100 parts by mass per minute.

[0514] Simultaneously with the transfer of this molten crystalline polyester resin, dilute ammonia water with a concentration of 0.37% by mass, which was prepared by diluting 70 parts by mass of reagent ammonia water with ion-exchanged water in an aqueous solvent tank, was transferred to the emulsifying and dispersing machine "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) at a transfer rate of 0.1 liters per minute while being heated to 100°C in a heat exchanger.

[0515] Then, this emulsifying and dispersing machine "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) was operated at a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm. 2 By operating under the above conditions, a dispersion of fine particles of a crystalline polyester resin with a solid content of 30 parts by mass was prepared.

[0516] At this time, the particles contained in the crystalline polyester resin particle dispersion had a volume-based median diameter of 200 nm.

[0517] <Preparation of Aqueous Dispersion of Amorphous Resin Particles (X1)> (First stage polymerization) A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with 8 parts by mass of sodium dodecyl sulfate and 3,000 parts by mass of ion-exchanged water, and the internal temperature was raised to 80° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. After the temperature was raised, a solution of 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added, and the liquid temperature was again raised to 80° C. Styrene 480 parts by mass n-Butyl acrylate 250 parts by mass Methacrylic acid 68.0 parts by mass The monomer mixture liquid consisting of the above was added dropwise over 1 hour, and then the mixture was heated at 80° C. for 2 hours with stirring to carry out polymerization, thereby preparing a dispersion liquid (x1) of resin fine particles.

[0518] (Second stage polymerization) A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device was charged with a solution of 7 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate dissolved in 3,000 parts by mass of ion-exchanged water, heated to 98 ° C, and then mixed with 260 parts by mass of a dispersion of resin fine particles (x1), Styrene (St) 284 parts by mass n-Butyl acrylate (BA) 92 parts by mass Methacrylic acid (MAA) 13 parts by mass n-Octyl-3-mercaptopropionate 1.5 parts by mass Release agent: behenic acid behenate (melting point 73°C) 190 parts by mass A solution of the monomer and release agent dissolved at 90°C was added, and the mixture was mixed and dispersed for 1 hour using a mechanical disperser "CLEARMIX" (manufactured by M Technique Co., Ltd.) with a circulation path to prepare a dispersion containing emulsified particles (oil droplets).

[0519] Next, an initiator solution in which 6 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 84°C for 1 hour to carry out polymerization, thereby preparing a dispersion of resin microparticles (x2).

[0520] (Third stage polymerization) Further, 400 parts by mass of ion-exchanged water was added to the dispersion liquid (x2) of resin fine particles and mixed well, and then a solution in which 11 parts by mass of potassium persulfate was dissolved in 400 parts by mass of ion-exchanged water was added, and the mixture was stirred at a temperature of 82°C. Styrene (St) 350 parts by mass n-Butyl acrylate (BA) 215 parts by mass Acrylic acid (AA) 30 parts by mass n-Octyl-3-mercaptopropionate 8 parts by mass After the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28°C to prepare an aqueous dispersion (X1) of amorphous resin particles made of vinyl resin.

[0521] The resulting aqueous dispersion (X1) of amorphous resin particles had a volume-based median diameter of 220 nm, a glass transition temperature (Tg) of 55°C, and a weight-average molecular weight (Mw) of 32,000.

[0522] <Preparation of aqueous dispersion of colorant particles (Cy1)> 90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water.

[0523] While stirring this solution, 420 parts by mass of copper phthalocyanine (CI Pigment Blue 15:3) was gradually added, followed by dispersion treatment using a stirring device "Clearmix" (manufactured by M Technique Co., Ltd.) to prepare an aqueous dispersion of colorant particles (Cy1).

[0524] The resulting aqueous dispersion (Cy1) of colorant particles had a volume-based median particle diameter of 110 nm.

[0525] <Production of Cyan Toner 1> A reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube was charged with 288 parts by mass (solid content equivalent) of an aqueous dispersion of amorphous resin microparticles (X1), 70 parts by mass (solid content equivalent) of an aqueous dispersion of hybrid crystalline polyester resin microparticles (C1), and 2,000 parts by mass of ion-exchanged water, and then a 5 mol / L aqueous sodium hydroxide solution was added to adjust the pH to 10.

[0526] Then, 30 parts by mass (solids equivalent) of an aqueous dispersion of colorant particles (Cy1) was added, and then an aqueous solution of 60 parts by mass of magnesium chloride dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30°C while stirring.

[0527] After that, the system was left for 3 minutes, and then the temperature was increased to 80°C over 60 minutes, and the particle growth reaction was continued while the temperature was maintained at 80°C.

[0528] In this state, the particle size of the associated particles was measured using a Coulter Multisizer 3 (manufactured by Coulter-Beckman), and when the volume-based median diameter reached 6.0 μm, an aqueous solution of 190 parts by mass of sodium chloride dissolved in 760 parts by mass of ion-exchanged water was added to stop particle growth.

[0529] The temperature was further increased and the particles were heated and stirred at 90°C to promote particle fusion. When the average circularity of the toner reached 0.945 (HPF detection count: 4,000 particles) using an "FPIA-2100" (Sysmex Corporation) measuring device, the particles were cooled to 30°C at a cooling rate of 2.5°C / min.

[0530] Next, the toner cake was subjected to solid-liquid separation, and the dehydrated toner cake was washed by repeating the process of re-dispersing the toner cake in ion-exchanged water and separating the solid from the liquid three times. After that, the toner cake was dried at 40°C for 24 hours to obtain toner base particles 1.

[0531] To 100 parts by mass of the obtained toner base particles 1, 0.6 parts by mass of hydrophobic silica (number average primary particle size = 12 nm, hydrophobicity = 68), 1.0 part by mass of hydrophobic titanium oxide (number average primary particle size = 20 nm, hydrophobicity = 63), and 0.30 parts by mass of zinc stearate as a fatty acid metal salt were added, and the mixture was mixed in a "Henschel Mixer" (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotor peripheral speed of 35 mm / sec and 32°C for 20 minutes. After that, an external additive treatment was performed to remove coarse particles using a sieve with 45 μm openings, thereby obtaining cyan toner 1 with a volume average particle size of 6.1 μm.

[0532] <Production of Cyan Toners 2 and 3> Cyan toners 2 and 3 were obtained in the same manner as in the production of cyan toner 1, except that the amount of zinc stearate used as the fatty acid metal salt was changed to 0.10 parts by mass and 0.15 parts by mass, respectively.

[0533] [Manufacturing of developer] A ferrite carrier coated with an acrylic resin and having a volume average particle size of 60 μm was added to each of the cyan toners 1 to 3 and mixed so that the toner concentration in the developer was 6.5 mass %, thereby producing each of the developers.

[0534] [Fabrication of Electrophotographic Image Forming System 1] In a bizhub C650i machine (manufactured by Konica Minolta), the drum unit was disassembled and replaced with the prepared photoreceptor 1 and cleaning blade a, respectively. Under the condition of a contact force of 12 N / m, the effective contact angle of the cleaning blade was changed as shown in Table I, and the machine was installed in the cyan color position to prepare an electrophotographic image forming system 1 using the prepared developer, cyan toner 1.

[0535] [Preparation of Electrophotographic Image Forming Systems 2 to 27] In a bizhub C650i machine (manufactured by Konica Minolta), the drum unit was disassembled and replaced with the prepared photoreceptors 1 to 8 and cleaning blades a to k, respectively. Under the condition of a contact force of 12 N / m, the effective contact angle of the cleaning blade was changed as shown in Tables II and III, and the machine was installed in the cyan color position, and electrophotographic image forming systems 2 to 27 were produced using the prepared developers, cyan toners 1 to 3, respectively.

[0536] Evaluation Method (1) Evaluation of streaky adhesion Using the above systems 1 to 27, 100,000 images of an image chart with a magenta solid patch 15 mm wide in the conveyance direction and 290 mm wide perpendicular to the conveyance direction were printed on one side of A4 paper. The voltage applied to the charging member was set to 200 V higher than the machine specification, and the evaluation was performed under conditions that would likely promote the formation of external additive adhesion due to the discharge load. The evaluation was performed in a low-temperature, low-humidity environment of 10°C / 20% RH, which is a severe condition that would likely cause external additives to slip through due to factors such as a high charge amount.

[0537] After printing, the photosensitive drum was inspected over its entire length for the presence or absence of streak-like adhesion, and each line was scored as follows: if a cyan streak was clearly visible to the naked eye, it was given 2 points, and if a transparent streak was visible under light, it was given 1 point. The lower the total score, the better the streak-like adhesion, and a score of 30 or less was considered pass.

[0538] In addition, the evaluation was discontinued for devices that failed the blade noise and blade curl evaluation described below.

[0539] (2) Evaluation of blade noise and curling Using the above systems 1 to 26, the cleaning blade was adjusted so that the contact force was 27 N / m.

[0540] 1,000 blank sheets were printed on a bizhub C650i in a high-temperature, high-humidity environment of 30°C and 80% RH, where the tip of the cleaning blade is likely to be retracted. During printing, we checked to see if there was any squealing (loud noise caused by blade vibration) or curling, and if there was no such noise, we deemed it a pass.

[0541] (3) Evaluation of photoconductor wear In the evaluation of streaky adhesion, the thickness of the surface protective layer on the photoreceptor was measured at 5 mm intervals in the longitudinal direction using an optical film thickness meter before and after printing, and the average amount of wear after printing 100,000 sheets was calculated. A sample with an average wear of 0.10 μm or less was deemed to have passed.

[0542] (4) Evaluation of pattern memory Using the above systems 1 to 27, a vertical solid band image was printed on a transfer material: A3 / POD gloss coat (A3 size, 100g / m) in a low temperature and low humidity environment of 10℃ and 20%RH. 2 20 sheets were printed continuously on a sheet of "Oji Paper Co., Ltd." (manufactured by Oji Paper Co., Ltd.), followed by printing three full-surface solid images. The occurrence of history in the solid band areas of the resulting full-surface solid images, i.e., the occurrence of pattern memory, was evaluated according to the following evaluation criteria.

[0543] Using a densitometer (RD-918; Gretag-Macbeth), the reflection density of the area corresponding to the solid band history and the area not corresponding to the solid band history were measured, and the difference between the two measured reflection densities (ΔID) was calculated.

[0544] If the ΔID of the entire solid surface was less than 0.010, the pattern memory was deemed to have passed. The configurations of the photoreceptor, cleaning blade and developer, as well as the evaluation results, are shown in Tables II and III.

[0545] [Table 2]

[0546] [Table 3]

[0547] From the evaluation results in Tables II and III, it was found that systems 1 to 20 of the examples, which have a photoreceptor protective layer according to the present invention and are equipped with a cleaning blade having an edge angle and an effective contact angle, passed the streak-like adhesion, turn-up test, surface protective layer wear amount (durability), and pattern memory tests compared to the comparative examples, suppressing the occurrence of streak-like adhesion due to aggregates derived from external additives, ensuring the wear resistance and charge transport properties of the photoreceptor, and providing an image forming system which combines excellent durability of the photoreceptor with good image quality. Furthermore, it was found that when the edge angle of the cleaning blade is in the range of 95 to 110°, the effective contact angle is in the range of 9 to 17°, and the ratio of the free length L to the thickness d (L / d) is 3.5 or more, the extent of improvement in streak adhesion is significant. [Explanation of symbols]

[0548] 1 Surface protective layer 2 Lubricant particles 3 Cleaning Blade α, β Effective contact angle 4 Wedge space 10 Photoreceptor 100 Image forming device 110Y, 110M, 110C, 110Bk Image forming unit 111Y, 111M, 111C, 111Bk photoconductor 113Y, 113M, 113C, 113Bk Charging means, charging roller 115Y, 115M, 115C, 115Bk Exposure means 117Y, 117M, 117C, 117Bk developing means 118Y, 118M, 118C, 118Bk developing roller 119Y, 119M, 119C, 119Bk, 135 cleaning unit 119a Cleaning Blade 119b Recovery screw 131 Intermediate transfer body 133Y, 133M, 133C, 133Bk Primary transfer roller (transfer means) 137A, 137B, 137C, 137D Rollers 150 Paper feed and transport means 170 Fixing means 200 Process Cartridge 201 Case 203R, 203L support rails 211 Paper cassette 213A, 213B, 213C, 213D Intermediate rollers 215 Resist Roller 217 Secondary transfer roller (transfer means) 219 Paper ejection roller 221 Paper output tray S1 power supply P Transfer material SC Document Image Reader C L Cleaning blade P g sheet metal C Contact part E Edge θ1 effective contact angle θ2 Rigid body contact angle θ3 Upstream wedge angle θ e Edge Angle L free length d Thickness

Claims

1. forming an electrostatic latent image on at least a photoreceptor; developing the image using a toner for developing an electrostatic image; and removing the toner for developing the electrostatic image by pressing a ridge portion of a cleaning blade against the surface of the photosensitive member, the photoreceptor has a photosensitive layer and a surface protective layer provided on the surface of the photosensitive layer, the surface protective layer contains at least a polymerizable monomer having two or more polymerizable groups in the molecule, and a polymer of a hole transport compound having a polymerizable group of a structure represented by the following general formula (1): the electrostatic image developing toner contains a fatty acid metal salt as an external additive, and the amount of the fatty acid metal salt added is 0.15% by mass or more based on the toner base particles; and The electrophotographic image forming system is characterized in that a tip edge portion of a cleaning blade having an obtuse edge angle of 120° or less is brought into pressure contact with the surface of the photosensitive member at an effective contact angle in the range of 8 to 20°. 【Chemistry 1】 (In the formula, Ar １ and Ar ２ represents a linking group represented by the following structural formula (7): ５ represents a group represented by the following structural formula (8) or (9). Ar ５ is structural formula (8), the total number of Ds (c1+c2+c5) is 1 or 2, Ar ５ In the case of structural formula (9), the total number of Ds (c1+c2+c5) is 1. 【Chemistry 2】 * indicates the bonding position with N or D. c1, c2, and c5 each independently represent 0 or 1. When c1, c2, and c5 each independently represent 0, a hydrogen atom is bonded to the bonding position with D. When c1, c2 and c5 are each independently 1, D is -(-(CH ２ ) ｄ -(O-(CH ２ ) ｆ -) ｅ -O-CO-C(CH ３ ) = CH ２ ) or -(-(CH ２ ) ｄ -(O-(CH ２ ) ｆ -) ｅ -O-CO-CH=CH ２ d and f each independently represent an integer of 0 to 5. e represents 0 or 1. The R ５ and R ６ each independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom. t represents an integer of 1 to 3. R ６ may be bonded to each other, so that the structural formula (9) has a cyclic structure.

2. 2. The electrophotographic image forming system according to claim 1, wherein the ratio (L / d) of the free length L to the thickness d of the cleaning blade is 3.5 or more.

3. The Ar of the hole transport compound ５ 3. The electrophotographic image forming system according to claim 1, wherein: is a linking group represented by the structural formula (9), and the total number of D's is 1.

4. 4. The electrophotographic image forming system of claim 3, wherein at least one of d and e in the structural formula of D of the hole transporting compound is 1 or greater.

5. 5. The electrophotographic image forming system according to claim 1, wherein the effective contact angle is within a range of 9 to 17 degrees.

6. 6. An electrophotographic imaging system according to claim 1, wherein the edge angle is in the range of 95 to 110 degrees.

7. 7. The electrophotographic image forming system according to claim 1, wherein the polymer of the hole transport compound is contained in the surface protective layer in an amount of 30 to 70% by mass.

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