JP5323000B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device which allows improved wear resistance of photoreceptor and suppressed generation of image defects without adding any special component to guard against abrasion of photoreceptor. <P>SOLUTION: In an electrophotographic photoreceptor, resin containing polycarbonate copolymer represented by the following formula is used as binder resin contained in a photosensitive layer on a conductive substrate, and the silica content in a toner should be 2.5-6 mass% in the mass of the toner. [In the formula (I), n+m=1 and 0.35&ge;m&lt;0.7 should be satisfied. W<SP POS="POST">1</SP>should be any of a single bond, -O-, or -CO-. Each of R<SP POS="POST">1</SP>, R<SP POS="POST">2</SP>, R<SP POS="POST">3</SP>and R<SP POS="POST">4</SP>should be any of a hydrogen atom, an alkyl group, or an aryl group, independently. R<SP POS="POST">3</SP>and R<SP POS="POST">4</SP>may be combined with each other to form a cycloalkylidene group.] <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus in which the wear resistance of a photoreceptor is improved and the occurrence of image defects is suppressed.

  The electrophotographic image forming apparatus includes an electrophotographic photoreceptor having an inorganic photoreceptor having a photosensitive layer made of an inorganic material such as selenium, and mainly organic materials such as a binder resin, a charge generator, and a charge transport agent. Some include an organic photoreceptor having a photosensitive layer made of a material. Organic photoreceptors are easier to manufacture than inorganic photoreceptors, and the photosensitive layer material can be selected from a wide range of materials and has a high degree of design freedom. It is used.

  In recent years, the contact charging method has been adopted as a method of charging the photoconductor in order to suppress the generation of ozone during charging of the photoconductor for the purpose of extending the life of the photoconductor and considering the environment in the office. Is increasing.

  However, organic photoconductors have the above-mentioned advantages, but organic materials are generally soft materials, so they are easily worn by repeated use. When a contact charging type charging unit such as a charging roller is used, the photoconductor is photosensitive. There is a problem that the body surface is significantly worn.

  For this reason, many studies have been made on improving the wear resistance of the photosensitive member with respect to an image forming apparatus employing a contact charging type charging unit. However, when the organic photoconductor is difficult to wear, the surface of the photoconductor is not renewed due to wear, so that the toner as a developer and the components contained in the toner are likely to remain on the surface of the photoconductor. There is a problem that image defects such as streaky image stains are likely to occur. For this reason, it is desired to develop an image forming apparatus in which the wear resistance of the photoreceptor is improved and the occurrence of image defects is suppressed.

  As a method for solving such a problem related to an image forming apparatus employing a charging roller as a charging unit, for example, Patent Document 1 discloses protection of an image carrier containing a fatty acid metal salt and boron nitride on the surface of a photoreceptor (image carrier). A method of supplying the agent has been proposed.

JP 2010-039304 A

  However, in the method described in Patent Document 1, in the image forming apparatus, it is necessary to install a component that supplies a protective agent for the surface of the photoreceptor near the photoreceptor. For this reason, in the image forming apparatus described in Patent Document 1, the manufacturing cost is increased, and the downsizing of the image forming apparatus is hindered. Therefore, the image forming apparatus cannot meet the market demand for downsizing and lowering the price of the image forming apparatus. From such a problem, a method for solving the problem of the abrasion resistance of the photosensitive member and the problem of occurrence of image defects without adding special parts to the image forming apparatus is desired.

  The present invention has been made in view of such circumstances, and without adding special parts for preventing wear of the photoconductor, the wear resistance of the photoconductor is improved and the occurrence of image defects is suppressed. Another object of the present invention is to provide an image forming apparatus.

The present inventors applied voltage to the electrophotographic photosensitive member as an image carrier , a toner containing at least a resin, a colorant, a release agent, and silica, a developing unit using the toner, and the surface of the electrophotographic photosensitive member. In an image forming apparatus including a charging roller, an electrophotographic photosensitive member in which a photosensitive layer containing a specific binder resin is formed on a conductive substrate is used. It has been found that by setting the content to not less than 6% by mass and not more than 6% by mass, the wear resistance of the photoreceptor in the image forming apparatus is improved and the occurrence of image defects is suppressed, and the present invention has been completed. More specifically, the present invention provides the following.

〔一般式（Ｉ）中、ｎ＋ｍ＝１であり、０．３５≦ｍ＜０．７である。Ｗ^１は単結合、−Ｏ−、又は−ＣＯ−である。Ｒ^１〜Ｒ^４はそれぞれ独立に、水素原子、アルキル基、又はアリール基であり、Ｒ^３及びＲ^４は互いに結合してシクロアルキリデン基を形成してもよい。〕 (1) An voltage is applied to the electrophotographic photosensitive member as an image carrier, a toner containing at least a resin, a colorant, a release agent, and silica, a developing unit using the toner , and the surface of the electrophotographic photosensitive member. An image forming apparatus comprising a charging roller,
The electrophotographic photoreceptor has a photosensitive layer formed on a conductive substrate,
The photosensitive layer is
1) a photosensitive layer in which a charge generation layer containing at least a charge generation agent, a charge transport layer containing at least a charge transfer agent and a binder resin are sequentially laminated, or
2) A photosensitive layer containing at least a charge generator, a charge transport agent, and a binder resin,
The binder resin contains a copolymer polycarbonate resin represented by the following general formula (I):
An image forming apparatus, wherein the content of silica in the toner is 2.5% by mass or more and 6% by mass or less in the mass of the toner.

[In General Formula (I), n + m = 1, and 0.35 ≦ m <0.7. W ¹ is a single bond, —O—, or —CO—. R ^{1 to} R ⁴ are each independently a hydrogen atom, an alkyl group, or an aryl group, and R ³ and R ⁴ may be bonded to each other to form a cycloalkylidene group. ]

  (2) The image forming apparatus according to (1), wherein the toner has an average particle diameter of 4.5 to 6.5 μm.

  (3) The image forming apparatus according to (1) or (2), wherein the release agent is a hydroxy acid ester wax.

  (4) The image forming apparatus according to any one of (1) to (3), wherein the resin in the toner is a polyester resin.

〔一般式（ＩＩ）中、ｐ＋ｑ＝１であり、０≦ｐ＜０．３５である。Ｗ^２は単結合、−Ｏ−、又は−ＣＯ−である。Ｒ^５〜Ｒ^８はそれぞれ独立に、水素原子、アルキル基、又はアリール基であり、Ｒ^７及びＲ^８は互いに結合してシクロアルキリデン基を形成してもよい。〕 (5) The binder resin further includes a polycarbonate resin represented by the following general formula (II), and the content of the copolymer polycarbonate resin represented by the general formula (I) is represented by the general formula (II). The image forming apparatus according to any one of (1) to (4), wherein the content is 2 to 30 times by mass based on the content of the polycarbonate resin represented.

[In General Formula (II), p + q = 1 and 0 ≦ p <0.35. W ² is a single bond, —O—, or —CO—. R ^{5 to} R ⁸ are each independently a hydrogen atom, an alkyl group, or an aryl group, and R ⁷ and R ⁸ may be bonded to each other to form a cycloalkylidene group. ]

(6) In the electrophotographic photosensitive member, the content of the charge transport agent is 55 parts by mass or less with respect to 100 parts by mass of the binder resin, (1) to (5) Image forming apparatus.

〔一般式（ＩＩＩ）中、Ｒ^９〜Ｒ^１５はそれぞれ独立に、水素原子、アルキル基、アルコキシ基、又はアリール基であり、Ｒ^１１〜Ｒ^１５から選択される隣接する２つの基は互いに結合して環を形成してもよい。ａは０〜５の整数を表す。〕

〔一般式（ＩＶ）中、Ｒ^１６〜Ｒ^２３はそれぞれ独立に、水素原子、アルキル基、アルコキシ基、又はアリール基である。ｂは０〜５の整数を表し、ｃは０〜４の整数を表し、ｋは０又は１を表す。〕 (7) In the electrophotographic photoreceptor, any one of (1) to (6), wherein the charge transfer agent is a compound represented by the following general formula (III) or the following general formula (IV): The image forming apparatus described.

[In General Formula (III), R ^{9 to} R ¹⁵ are each independently a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, and two adjacent groups selected from R ^{11 to} R ¹⁵ are bonded to each other. To form a ring. a represents an integer of 0 to 5. ]

[In General Formula (IV), R ^{16 to} R ²³ are each independently a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group. b represents an integer of 0 to 5, c represents an integer of 0 to 4, and k represents 0 or 1. ]

  According to the present invention, it is possible to obtain an image forming apparatus in which the wear resistance of the photoconductor is improved and the occurrence of image defects is suppressed without adding special parts for preventing the photoconductor from being worn.

FIG. 2 is a diagram showing a configuration of a multilayer photoreceptor used in the image forming apparatus of the present invention. 1 is a diagram illustrating a configuration of a single-layer type photoreceptor used in an image forming apparatus of the present invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention.

  Hereinafter, although embodiment of this invention is described, this invention is not limited to these.

The image forming apparatus of the present invention includes an electrophotographic photosensitive member as an image carrier , a toner containing at least a resin, a colorant, a release agent, and silica, a developing unit using the toner, and a voltage applied to the surface of the electrophotographic photosensitive member. An image forming apparatus including a charging roller for applying a voltage. Hereinafter, the electrophotographic photosensitive member, the developing unit, the charging roller, and the image forming apparatus will be described in order.

[Electrophotographic photoreceptor]
An electrophotographic photosensitive member (hereinafter sometimes simply referred to as a photosensitive member) used as an image carrier in the image forming apparatus of the present invention is an organic photosensitive member. There are two types of electrophotographic photoreceptors, a single layer type and a multilayer type, and any of the image forming apparatuses of the present invention is applicable.

In the specification and claims of the present application, the resin contained in the charge transport layer of the multilayer photoreceptor or the photosensitive layer of the single-layer photoreceptor is referred to as “binder resin”. In addition, when the charge generation layer of the multilayer photoreceptor includes a resin, the resin included in the charge generation layer is referred to as a “base resin”. Hereinafter, the laminated photoreceptor and the single-layer photoreceptor will be described in order.

1. Multilayer Photoreceptor As shown in FIG. 1A, a multilayer photoreceptor 10 is formed by forming a charge generation layer 12 containing a charge generation agent on a conductive substrate 11 by means of vapor deposition or coating, It can be formed by applying a coating liquid containing a charge transport agent and a specific binder resin on the charge generation layer 12 and then drying to form the charge transport layer 13.

  The laminated electrophotographic photosensitive member can be applied to both positive and negative charging systems by appropriately selecting the type of the charge transport agent.

  Further, as shown in FIG. 1B, it is also preferable to previously form the undercoat layer 14 on the conductive substrate 11 before forming the photosensitive layer. By providing the undercoat layer 14, the charge on the conductive substrate 11 side is prevented from being injected into the photosensitive layer, and the binding of the photosensitive layer onto the conductive substrate 11 is strengthened. This is because defects can be covered and smoothed.

  Hereinafter, the conductive substrate and the photosensitive layer will be described in order with respect to the multilayer photoreceptor.

[Conductive substrate]
The conductive substrate used in the multilayer photoreceptor is not particularly limited as long as it can be used as the conductive substrate of the electrophotographic photoreceptor. Specifically, for example, a material having at least a surface portion made of a conductive material can be used. Specifically, for example, it may be made of a conductive material, or may be a plastic material or the like whose surface is covered with a conductive material. As a material having conductivity, for example, aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, Kado Mi um, titanium, nickel, palladium, indium, stainless steel, brass and the like . Moreover, as a material which has electroconductivity, the material which has electroconductivity may be used by 1 type, and may be used as an alloy etc., for example, combining 2 or more types. Further, among the above, the conductive substrate is preferably made of aluminum or an aluminum alloy. By doing so, a photoconductor capable of forming a more suitable image can be provided. This is considered to be due to good charge transfer from the photosensitive layer to the conductive substrate.

  The shape of the conductive substrate can be appropriately selected according to the structure of the image forming apparatus to be used. For example, a sheet-like or drum-like substrate can be suitably used.

(Photosensitive layer)
<Materials constituting photosensitive layer>
The multilayer photoreceptor is composed of a charge generation layer containing at least a charge generation agent and a charge transport layer containing at least a charge transfer agent and a binder resin formed on a conductive substrate, and the charge generation layer comprises a base resin. May be included. Hereinafter, the binder resin, the charge transport agent, the charge generator, and the base resin will be described in order.

(Binder resin)
As the binder resin used for the charge transport layer of the multilayer photoreceptor, a resin containing a copolymerized polycarbonate resin represented by the following general formula (I) (hereinafter also referred to as binder resin I) is used. In addition to the binder resin I, the binder resin is more preferably a resin containing a polycarbonate resin represented by the following general formula (II) (hereinafter also referred to as a binder resin II). When a resin containing the binder resin I and the binder resin II is used as the binder resin, crystallization of the charge transport agent contained in the charge transport layer can be easily suppressed, and the photoreceptor can be excellent in electrical characteristics.

〔一般式（Ｉ）中、ｎ＋ｍ＝１であり、０．３５≦ｍ＜０．７である。Ｗ^１は単結合、−Ｏ−、又は−ＣＯ−である。Ｒ^１〜Ｒ^４はそれぞれ独立に、水素原子、アルキル基、又はアリール基であり、Ｒ^３及びＲ^４は互いに結合してシクロアルキリデン基を形成してもよい。〕

[In General Formula (I), n + m = 1, and 0.35 ≦ m <0.7. W ¹ is a single bond, —O—, or —CO—. R ^{1 to} R ⁴ are each independently a hydrogen atom, an alkyl group, or an aryl group, and R ³ and R ⁴ may be bonded to each other to form a cycloalkylidene group. ]

〔一般式（ＩＩ）中、ｐ＋ｑ＝１であり、０≦ｐ＜０．３５である。Ｗ^２は単結合、−Ｏ−、又は−ＣＯ−である。Ｒ^５〜Ｒ^８はそれぞれ独立に、水素原子、アルキル基、又はアリール基であり、Ｒ^７及びＲ^８は互いに結合してシクロアルキリデン基を形成してもよい。〕

[In General Formula (II), p + q = 1 and 0 ≦ p <0.35. W ² is a single bond, —O—, or —CO—. R ^{5 to} R ⁸ are each independently a hydrogen atom, an alkyl group, or an aryl group, and R ⁷ and R ⁸ may be bonded to each other to form a cycloalkylidene group. ]

When the substituents R ^{1 to} R ^{8 of the} copolymeric polycarbonate of the general formula (I) or the polycarbonate of the general formula (II) are alkyl groups, an alkyl group having 1 to 12 carbon atoms is preferable, and 1 to 1 carbon atoms are preferable. An alkyl group having 8 carbon atoms is more preferable, and an alkyl group having 1 to 6 carbon atoms is particularly preferable.

Specific examples of the substituent represented by R ^{1 to} R ⁸ being an alkyl group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, a ter -Butyl group, n-pentyl group, iso-pentyl group, tert-pentyl group, neopentyl group, n-hexyl group, iso-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, tert-octyl Group, n-nonyl group, n-decyl group, n-undecyl group and the like.

In the general formulas (I) and (II), R ³ and R ⁴ , and R ⁷ and R ⁸ may be bonded to each other to form a ring. When R ³ and R ⁴ , and R ⁷ and R ⁸ form a ring, the ring is preferably a 4- to 8-membered ring, more preferably a 5- to 6-membered ring.

In the general formulas (I) and (II), when the substituents R ^{1 to} R ⁸ are aryl groups, a phenyl group or a group formed by condensing 2 to 6 benzene rings or connecting them by a single bond Is preferred. 1-6 are preferable, as for the number of the benzene rings contained in an aryl group, 1-3 are more preferable, and 1 or 2 is especially preferable.

Specific examples of the substituent represented by R ^{1 to} R ⁸ being an aryl group include a phenyl group, a naphthyl group, a biphenylyl group, an anthryl group, a phenanthryl group, and a pyrenyl group.

W ¹ in the general formula (I) is more preferably a single bond. By using a binder resin in which W ¹ is a single bond, it is easy to obtain a photoreceptor having particularly excellent wear resistance.

The content of Ba inductor resin I in the binder resin in the charge transporting layer is not particularly limited within a range that does not impair the object of the present invention. The content of the binder resin I is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more based on the total amount of the binder resin. By including the amount of the binder resin I in such a range, the wear of the photoconductor can be remarkably suppressed.

  When binder resin I and binder resin II are used in combination in the charge transport layer, the content of each resin is not particularly limited as long as the object of the present invention is not impaired. The content of the binder resin I is preferably 2 times or more and 30 times or less, more preferably 2.5 times or more and 20 times or less, and particularly preferably 3 times or more and 10 times or less with respect to the content of the binder resin II. preferable. By setting the content of the binder resin I and the binder resin II in such a range, the compatibility between the charge transport agent and the binder resin can be improved without impairing the abrasion resistance of the photoreceptor, and the crystallization of the charge transport agent is suppressed. Therefore, a photoreceptor having excellent electrical characteristics can be obtained.

  The manufacturing method of the binder resin I and the binder resin II is not particularly limited. Binder resin I and binder resin II can be manufactured according to the manufacturing method of a well-known polycarbonate resin, for example using the bisphenol compound corresponding to the repeating unit as described in general formula (I) and (II).

  As the binder resin I and the binder resin II, any of a random copolymer and a block copolymer can be used as long as the object of the present invention is not impaired. In addition, the binder resin I and the binder resin II preferably have a viscosity average molecular weight of 5,000 to 200,000, and more preferably 20,000 to 60,000. By setting the viscosity average molecular weight of the binder resin in such a range, the binder resin has an appropriate hardness, and the charge transfer agent is well dispersed in the binder resin, thereby being excellent in electrical characteristics and abrasion resistance. Is obtained.

The viscosity average molecular weight [M] of the polycarbonate resin can be calculated from [η] = 1.23 × 10 ⁻⁴ M ^{0.83 according} to Schnell's equation, by obtaining the intrinsic viscosity [η] with an Ostwald viscometer. [Η] can be measured using a polycarbonate resin solution obtained by dissolving a polycarbonate resin at 20 ° C. using methylene chloride as a solvent so that the concentration becomes 6.0 g / dm ³ .

  The content of the binder resin I and the binder resin II with respect to the total amount of the binder resin in the charge transport layer is not particularly limited as long as the object of the present invention is not impaired, but is preferably 70% by mass or more, more preferably 90% by mass or more. 100% by mass is particularly preferable.

  The binder resin of the charge transport layer may contain other resins of the binder resin I and the binder resin II as long as the object of the present invention is not impaired. The resin that the binder resin of the charge transport layer may contain includes polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic. Acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, polyurethane resin, Polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl acetal resin, polyvinyl butyral resin, polyether resin, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, epoxy acrylate resin, and urethane-acrylic resin Rate resins.

(Charge transport agent)
The charge transfer agent is not particularly limited as long as it can be used as a charge transfer agent contained in the photosensitive layer of the electrophotographic photosensitive member. Moreover, as a charge transport agent, a hole transport agent and an electron transport agent are generally mentioned.

Examples of the hole transport agent include benzidine derivatives, oxadiazole compounds such as 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, and 9- (4-diethylaminostyryl). Styryl compounds such as anthracene, carbazole compounds such as polyvinyl carbazole, organic polysilane compounds, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, triphenylamine compounds, indoles Examples thereof include nitrogen-containing cyclic compounds such as compound, oxazole compound, isoxazole compound, thiazole compound, thiadiazole compound, imidazole compound, pyrazole compound and triazole compound, and condensed polycyclic compounds. Among these, triphenylamine compounds are preferable, and triphenylamine compounds represented by the following general formula (III) or (IV) are more preferable.

〔一般式（ＩＩＩ）中、Ｒ^９〜Ｒ^１５はそれぞれ独立に、水素原子、アルキル基、アルコキシ基、又はアリール基であり、Ｒ^１１〜Ｒ^１５から選択される隣接する２つの基は互いに結合して環を形成してもよい。ａは０〜５の整数を表す。〕

[In General Formula (III), R ^{9 to} R ¹⁵ are each independently a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, and two adjacent groups selected from R ^{11 to} R ¹⁵ are bonded to each other. To form a ring. a represents an integer of 0 to 5. ]

〔一般式（ＩＶ）中、Ｒ^１６〜Ｒ^２３はそれぞれ独立に、水素原子、アルキル基、アルコキシ基、又はアリール基である。ｂは０〜５の整数を表し、ｃは０〜４の整数を表し、ｋは０又は１を表す。〕

[In General Formula (IV), R ^{16 to} R ²³ are each independently a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group. b represents an integer of 0 to 5, c represents an integer of 0 to 4, and k represents 0 or 1. ]

When the substituents R ^{9 to} R ^{23 included in the} compound represented by the general formula (III) or the general formula (IV) are alkyl groups, an alkyl group having 1 to 12 carbon atoms is preferable, and 1 to 8 carbon atoms are preferable. Are more preferable, and an alkyl group having 1 to 6 carbon atoms is particularly preferable.

Specific examples when the substituent represented by R ^{9 to} R ²³ is an alkyl group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, a ter -Butyl group, n-pentyl group, iso-pentyl group, tert-pentyl group, neopentyl group, n-hexyl group, iso-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, tert-octyl Group, n-nonyl group, n-decyl group, n-undecyl group and the like.

In the compound of the general formula (III), two adjacent groups selected from R ^{11 to} R ¹⁵ may be bonded to each other to form a ring. When two adjacent groups selected from R ^{11 to} R ¹⁵ form a ring, the ring is preferably a 4- to 8-membered ring, more preferably a 5- to 6-membered ring.

When the substituents R ^{9 to} R ^{23 included in the} compound represented by the general formula (III) or the general formula (IV) are alkoxy groups, an alkoxy group having 1 to 12 carbon atoms is preferable, and 1 to 8 carbon atoms is preferable. Are more preferable, and an alkoxy group having 1 to 6 carbon atoms is particularly preferable.

Specific examples when the substituent represented by R ^{9 to} R ²³ is an alkoxy group include a methoxy group, an ethoxy group, an n-propyloxy group, an iso-propyloxy group, an n-butyloxy group, and a sec-butyloxy group. , Tert-butyloxy group, n-pentyloxy group, iso-pentyloxy group, tert-pentyloxy group, neopentyloxy group, n-hexyloxy group, iso-hexyloxy group, n-heptyloxy group, n-octyl Examples thereof include an oxy group, 2-ethylhexyloxy group, tert-octyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group and the like.

When the substituents R ^{9 to} R ^{23 included in the} compound represented by the general formula (III) or the general formula (IV) are aryl groups, a phenyl group or 2 to 6 benzene rings are condensed or a single bond A group formed by linking with each other is preferred. 1-6 are preferable, as for the number of the benzene rings contained in an aryl group, 1-3 are more preferable, and 1 or 2 is especially preferable.

Specific examples of the substituent represented by R ^{9 to} R ²³ being an aryl group include a phenyl group, a naphthyl group, a biphenylyl group, an anthryl group, a phenanthryl group, and a pyrenyl group.

  The electron transporting agent that can be suitably used is not particularly limited as long as it can be used as the electron transporting agent contained in the photosensitive layer of the electrophotographic photosensitive member. Specifically, for example, quinone derivatives such as naphthoquinone derivatives, diphenoquinone derivatives, anthraquinone derivatives, azoquinone derivatives, nitroantharaquinone derivatives, dinitroanthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3, 4, 5, 7-tetranitro-9-fluorenone derivative, dinitroanthracene derivative, dinitroacridine derivative, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, succinic anhydride, maleic anhydride, dibromoanhydride And maleic acid. Of these, quinone derivatives are more preferable.

(Charge generator)
The charge generating agent used for the photosensitive layer of the multilayer photoreceptor is not particularly limited as long as it can be used as a charge generating agent for an electrophotographic photoreceptor. Specifically, X-type metal-free phthalocyanine (x-H2Pc), Y-type oxotitanyl phthalocyanine (Y-TiOPc), perylene pigment, bisazo pigment, dithioketopyrrolopyrrole pigment, metal-free naphthalocyanine pigment, metal naphthalocyanine pigment, SQUALINE pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, powders of inorganic photoconductive materials such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon, pyrylium salts, ansanthrone pigments, triphenyl Examples include methane pigments, selenium pigments, toluidine pigments, pyrazoline pigments, and quinacridone pigments.

  Moreover, a charge generation agent may be used independently so that it may have an absorption wavelength in a desired area | region, and may be used in combination of 2 or more type. Further, among the above-mentioned charge generating agents, digital image forming apparatuses such as laser beam printers and facsimiles using a light source such as a semiconductor laser, in particular, require a photosensitive member having sensitivity in a wavelength region of 700 nm or more. Therefore, for example, phthalocyanine pigments such as metal-free phthalocyanine and oxo titanyl phthalocyanine are preferably used. The crystal form of the phthalocyanine pigment is not particularly limited, and various types can be used. In addition, an image forming apparatus of an analog optical system such as an electrostatic copying machine using a white light source such as a halogen lamp requires a photosensitive member having sensitivity in the visible region. For example, a perylene pigment or a bisazo pigment Etc. are preferably used.

(Base resin)
When the charge generation layer is formed on a conductive substrate by applying a solution containing a charge generation agent, a base resin is used together with the charge generation agent. As the base resin used in the charge generation layer, a binder resin used in the charge transport layer can be used, and other binder resins used in the charge transport layer can also be used. Specific examples of other resins of the binder resin used in the charge transport layer that can be used as the base resin of the charge generation layer include bisphenol Z type polycarbonate resin, bisphenol ZC type polycarbonate resin, bisphenol C type polycarbonate resin, and bisphenol A type polycarbonate resin. , Polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer , Chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, polyurethane resin, polysulfone resin, diallyl Tallates resins, ketone resins, polyvinyl acetal resins, polyvinyl butyral resins, polyether resins, silicone resins, epoxy resins, phenol resins, urea resins, melamine resins, epoxy acrylate resins, and urethane - acrylate resins. The base resin used for the charge generation layer may be used alone or in combination of two or more.

<Method for creating photosensitive layer>
The photosensitive layer in the multilayer photoreceptor is formed by sequentially laminating a charge generation layer and a charge transport layer on a conductive substrate or an undercoat layer formed on the conductive substrate.

  The film thickness of the charge generation layer in the multilayer photoreceptor is preferably from 0.1 to 5 μm, more preferably from 0.1 to 3 μm. Moreover, 2-100 micrometers is preferable and, as for the film thickness of a charge transport layer, 5-50 micrometers is more preferable.

The content of the charge generation agent in the charge generation layer is not particularly limited as long as the object of the present invention is not impaired. When the charge generation layer is formed by application of a coating solution, the amount of the charge generation agent is preferably 10 to 500 parts by mass, more preferably 30 to 300 parts by mass with respect to 100 parts by mass of the base resin.

  The content of the charge transport agent in the charge transport layer is preferably 55 parts by mass or less, more preferably 5 to 55 parts by mass, and particularly preferably 10 to 55 parts by mass with respect to 100 parts by mass of the binder resin. The amount of the charge transport agent is the total amount of the hole transport agent and the electron transport agent in the charge transport layer. By setting the amount of the charge transfer agent in such a range, it is easy to obtain a laminated photoreceptor having excellent wear resistance.

  Examples of the method for forming the charge generation layer include vacuum deposition of a charge generation agent or application of a coating solution containing at least the charge generation agent, a base resin, and a solvent. As a method for forming the charge generation layer, it is preferable to apply a coating solution containing at least a charge generation agent, a base resin, and a solvent because an expensive vapor deposition apparatus is unnecessary and a film forming operation is easy. Moreover, as a formation method of a charge transport layer, application | coating of the coating liquid containing a charge transport agent, binder resin, and a solvent is mentioned at least.

  As the solvent used for preparing the coating solution for forming the photosensitive layer, various organic solvents conventionally used for the coating solution for forming the photosensitive layer can be used. Specifically, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane and chloroform , Halogenated hydrocarbons such as carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, dioxane, dioxolane, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; Esters such as ethyl and methyl acetate; N, N-dimethylformaldehyde, N, N-dimethylformamide, dimethyl sulfoxide, etc. Aprotic polar organic solvents.

Various conventionally known additives can be blended in the coating solution for the charge generation layer or the charge transport layer as long as the electrophotographic characteristics are not adversely affected. Suitable additives to be blended in the coating liquid include, for example, antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, Examples include thickeners, dispersion stabilizers, waxes, acceptors, donors and the like. In order to improve the dispersibility of the charge transporting agent and the charge generating agent and the smoothness of the photosensitive layer surface, a surfactant, a leveling agent and the like may be used.

  The method for applying the coating solution for the charge generation layer or the charge transport layer is not particularly limited, and examples thereof include a method using a spin coater, applicator, spray coater, bar coater, dip coater, doctor blade and the like.

  The film formed by applying the coating solution by the above method is dried using a high-temperature dryer, a vacuum dryer, or the like to remove the solvent, thereby forming a charge generation layer and a charge transport layer. The drying temperature is preferably 40 to 150 ° C. This is because, by drying the film in such a temperature range, the removal of the solvent proceeds rapidly, and the charge generation layer and the charge transport layer having a uniform thickness can be efficiently formed. When the drying temperature is too high, the components contained in the photosensitive layer may be thermally decomposed, which is not preferable.

Note that the undercoat layer includes a resin, and inorganic fine particles such as zinc oxide or titanium oxide, to prepare a coating liquid and a solvent, which can be formed by drying after application on a conductive substrate.

2. Single Layer Type Photoreceptor The electrophotographic photoreceptor used in the present invention can be used in any of positive and negative charging systems, and since the photosensitive layer is a single layer, the production of the photoreceptor is easy, and the interface between layers is It is also preferable to use a single-layer type photoreceptor because it has few optical properties and the like.

  As shown in FIG. 2A, the single-layer type photoreceptor 20 has a single photosensitive layer 21 provided on a conductive substrate 11. The photosensitive layer in the single-layer type photoreceptor is, for example, a coating liquid obtained by dissolving or dispersing a charge transport agent, a charge generator, a binder resin, and a leveling agent, if necessary, in an appropriate solvent. It can be formed by drying after coating on the conductive substrate 11.

  Further, as shown in FIG. 2B, it is also preferable to form a photosensitive layer 21 on the conductive substrate 11 via the undercoat layer 14.

  Hereinafter, regarding the single layer type photoreceptor used in the image forming apparatus of the present invention, the conductive substrate and the photosensitive layer will be described in order.

[Conductive substrate]
As the conductive substrate used for the single layer type photoreceptor, a substrate made of the same material as that of the conductive substrate used for the above-mentioned laminated type photoreceptor can be used. The shape of the conductive substrate can be appropriately selected according to the structure of the image forming apparatus to be used. For example, a substrate such as a sheet or a drum can be suitably used.

(Photosensitive layer)
<Materials constituting photosensitive layer>
Examples of main materials constituting the photosensitive layer in the single-layer type photoreceptor include a binder resin, a charge transport agent, and a charge generator. As the binder resin, a resin containing the binder resin I is used in the same manner as the binder resin contained in the charge transport layer of the multilayer photoconductor. The charge transport agent and charge generator can be made of the same material as that of the laminated photoreceptor.

<Method for producing photosensitive layer>
The photosensitive layer of a single layer type photoreceptor is prepared by preparing a coating liquid from a charge transport agent, a charge generator, a binder resin, and a solvent, and is the same method as the method for forming the charge generation layer and the charge transport layer in the multilayer photoreceptor. Can be formed.

The amount of the charge transfer agent used in the photosensitive layer of the single layer type photoreceptor is preferably 55 parts by mass or less, more preferably 5 to 55 parts by mass, and particularly preferably 10 to 55 parts by mass with respect to 100 parts by mass of the binder resin. . The amount of the charge transfer agent is the total amount of the hole transfer agent and the electron transfer agent in the photosensitive layer. By setting the amount of the charge transfer agent in such a range, it is easy to obtain a single layer type photoreceptor excellent in wear resistance.

  The amount of the charge generating agent used in the photosensitive layer of the single-layer type photoreceptor is preferably 0.01 to 30 parts by weight, more preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the binder resin. 10 parts by mass is particularly preferable. By setting the amount of the charge generating agent to be in such a range, it is possible to produce a photoreceptor having excellent electrical characteristics without reducing the abrasion resistance of the photoreceptor.

  The thickness of the photosensitive layer of the single layer type photoreceptor is not particularly limited as long as it has a function suitable as a photosensitive layer. Specifically, for example, 5 to 100 μm is preferable, and 10 to 50 μm is more preferable.

[toner]
The toner used in the present image portion Te present invention odor is a toner containing at least a resin, a colorant, a release agent, and silica. In the present invention, the toner to be used may contain a charge control agent if desired. Hereinafter, a resin, a colorant, a release agent, silica, a charge control agent, and a toner manufacturing method will be described in order.

(resin)
In the present invention, the resin contained in the toner is not particularly limited as long as the image characteristics of the image forming apparatus of the present invention are not impaired, and can be appropriately selected from various resins conventionally used as a resin for toner. Specific examples of resins contained in the toner include polystyrene resins, polyester resins, acrylic resins, styrene-acrylic copolymers, polyethylene resins, polypropylene resins, vinyl chloride resins, polyamide resins, and polyurethane resins. Examples thereof include thermoplastic resins such as resins, polyvinyl alcohol resins, vinyl ether resins, N-vinyl resins, and styrene-butadiene resins. Among these resins, polyester resins are preferable from the viewpoints of dispersibility with respect to the colorant in the toner, chargeability of the toner, and fixability with respect to the paper.

  Examples of suitable polyester resins include dicarboxylic acid components such as succinic acid, adipic acid, sebacic acid, terephthalic acid, and isophthalic acid, and diol components such as ethylene glycol, trimethylene glycol, and 1,4-butanediol. Examples thereof include copolymer polyesters obtained by condensation polymerization.

(Coloring agent)
Examples of the colorant contained in the toner in the present invention include black pigments such as acetylene black, run black, and aniline black; yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, and navels. Yellow pigments such as yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, red mouth yellow lead, molybdenum orange, permanent orange GTR, Orange pigments such as pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK; Bengala, cadmium red, red lead Red pigments such as mercury cadmium sulfide, permanent red 4R, resol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B; manganese purple, fast Purple pigments such as violet B and methyl violet lake; blue pigments such as bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, indanthrene blue BC Green pigments such as chrome green, chromium oxide, pigment green B, malachite green lake, and fanal yellow green G; zinc white, titanium oxide Antimony white, zinc sulfide, barite powder, barium carbonate, clay, silica, white carbon, talc, white pigments such as alumina white can be used. The content of the colorant in the toner is preferably 1.0 to 20.0 parts by mass and more preferably 3.0 to 10.0 parts by mass with respect to 100 parts by mass of the resin.

(Release agent)
As the release agent contained in the toner in the present invention, various waxes conventionally used in toners can be used as long as the object of the present invention is not impaired. Preferable examples of the wax that can be used in the present invention include hydroxy acid ester wax and paraffin wax. Examples of the hydroxy acid ester wax include natural waxes such as carnauba wax, rice wax, and montan wax, and synthetic waxes such as seryl-ω-hydroxyserotate, seryl-ω-hydroxymelitate, and myricyl-ω-hydroxymelitate. Can be mentioned. Among these waxes, hydroxy acid ester wax is preferable, natural wax is more preferable, and carnauba wax is further preferable from the viewpoint of offset resistance.

  In the present invention, the melting point of the wax contained in the toner is not limited as long as the object of the present invention is not impaired, but is preferably 80 ° C. or higher and 95 ° C. or lower, more preferably 81 ° C. or higher and 90 ° C. or lower, and 82 ° C. or higher and 88 ° C. or lower. The following are particularly preferred: By using such a melting point wax, it is easy to suppress the occurrence of image defects such as dash marks.

  The content of the wax in the toner is preferably 0.5 to 15.0 parts by mass and more preferably 1.0 to 10.0 parts by mass with respect to 100 parts by mass of the resin.

(silica)
In the present invention, silica is used as an external additive. The silica used as the external additive is not limited as long as it does not impair the object of the present invention, and can be appropriately selected from silica used for toner. The amount of silica is not more than 6 wt% 2.5 wt% or more with respect to the toner mass, the good preferable 3 wt% to 5 wt% or less. By setting the amount of silica used in such a range, a toner having excellent fluidity and charging characteristics can be obtained, and the occurrence of image defects such as abnormal image density and dash marks can be suppressed.

(Charge control agent)
The toner used in the present invention may contain a charge control agent in order to control the frictional charging characteristics of the toner. As the charge control agent, a charge control agent for positive charge control and / or negative charge control is used according to the charge polarity of the toner. The type of the charge control agent is not particularly limited. For example, nigrosine, triphenylmethane dye, molybdate chelate pigment, rhodamine dye, alkoxy amine, quaternary ammonium salt, alkylamide, phosphorus simple substance or compound, tungsten Or a compound, a fluorine-based activator, a metal complex of salicylic acid, a metal complex of salicylic acid derivative, a metal complex of oxynaphthoic acid, a metal complex of oxynaphthoic acid derivative, a phenol-based condensate, quinacridone, an azo pigment or the like.

(Toner production method)
The method for producing the toner used in the present invention is not particularly limited, and the toner can be produced by a kneading and pulverizing method, a polymerization method, a spinning method or the like. When the manufacturing method of the toner is a kneading and pulverizing method, for example, the toner is manufactured by the following procedure.

  First, the above-mentioned resin, colorant, release agent, charge control agent, etc. are mixed with a mixer such as a Henschel mixer, melt-kneaded with a twin screw extruder, etc., and then pulverized with a pulverizer such as a hammer mill. Get. The obtained powder is classified by a classifier such as an airflow classifier to obtain toner base particles. Toner is obtained by adding an external additive containing at least silica to the obtained toner base particles and mixing with a Henschel mixer or the like. The toner obtained as described above may be mixed with a carrier in which fine particles of a magnetic material such as iron are dispersed in resin particles to form a two-component toner.

  The particle diameter of the toner used in the present invention is preferably 1 to 10 μm, more preferably 2 to 8 μm, and particularly preferably 3 to 7 μm. The particle diameter of the toner can be determined by measuring 30000 counts with a Coulter counter type particle size distribution meter with an aperture diameter of 100 μm.

[Development part]
The developing unit provided in the image forming apparatus of the present invention supplies toner to the electrostatic latent image formed by exposing the surface of the photoreceptor, and develops the electrostatic latent image as a toner image. The toner image formed by the developing unit is transferred to the transfer target by the transfer unit.

[Charging roller]
The charging roller used as the contact-type charging unit is not particularly limited as long as the charging roller can charge the surface of the photosensitive member while being in contact with the surface of the photosensitive member. Examples of the charging roller include a roller that rotates depending on the rotation of the electrophotographic photosensitive member while being in contact with the surface of the drum-shaped photosensitive member. As the configuration of the charging roller, for example, a structure including a core bar rotatably supported, a resin layer formed on the core bar, and a voltage application unit that applies a voltage to the core bar, and the like can be given. Such a charging roller can charge the surface of the photoreceptor through a resin layer on the roller surface by applying a voltage to the cored bar by the voltage applying unit.

  The resin used for the resin layer in the charging roller is not particularly limited as long as the surface of the photoreceptor can be satisfactorily charged, and examples thereof include silicone resins, urethane resins, and silicone-modified resins. Moreover, you may mix | blend an inorganic filler with the resin layer of a charging roller.

  The voltage applied to the charging roller by the voltage application unit is preferably only a DC voltage. The amount of abrasion of the photosensitive layer tends to be smaller when only the DC voltage is applied to the charging roller than when the superimposed voltage obtained by superimposing the DC voltage on the AC voltage is applied to the charging roller.

[Image forming apparatus]
The image forming apparatus of the present invention includes an electrophotographic photosensitive member as the above-described image carrier, a charging roller for charging the surface of the electrophotographic photosensitive member, and an electrostatic latent image formed on the surface of the electrophotographic photosensitive member. Is not particularly limited as long as it includes a developing unit for developing the toner as a toner image.

  Further, a tandem color image forming apparatus using a plurality of color toners, which will be described later, is preferable. Here, a tandem color image forming apparatus will be described.

  The image forming apparatus provided with the electrophotographic photosensitive member according to the present embodiment includes a plurality of electrophotographic images arranged in parallel in a predetermined direction in order to form toner images with different colors of toner on the surfaces. A plurality of photosensitive members and a plurality of developing rollers that are arranged opposite to each electrophotographic photosensitive member, carry a toner carried on the surface, and supply the conveyed toner to the surface of each electrophotographic photosensitive member. Development unit.

  FIG. 3 is a schematic diagram showing the configuration of the image forming apparatus according to the embodiment of the present invention. Here, the color printer 1 will be described as an example.

  As shown in FIG. 3, the color printer 1 has a box-shaped device main body 1a. In the apparatus main body 1a, a toner image based on image data and the like is transferred to the paper P while feeding the paper P fed from the paper feeding unit 2 and the paper P fed from the paper feeding unit 2. An image forming unit 3 and a fixing unit 4 for performing a fixing process for fixing the unfixed toner image transferred onto the paper P by the image forming unit 3 to the paper P are provided. Further, on the upper surface of the apparatus main body 1a, a paper discharge unit 5 for discharging the paper P subjected to the fixing process by the fixing unit 4 is provided.

The paper feed unit 2 includes a paper feed cassette 121, a pickup roller 122, paper feed rollers 123, 124, 125, and a registration roller 126. The paper feed cassette 121 is provided so as to be detachable from the apparatus main body 1a, and stores the paper P of each size. The pickup roller 122 is provided at the upper left position of the paper feed cassette 121 shown in FIG. 3 and takes out the paper P stored in the paper feed cassette 121 one by one. The paper feed rollers 123, 124, and 125 send the paper P taken out by the pickup roller 122 to the paper transport path. The registration roller 126 temporarily waits for the paper P sent to the paper transport path by the paper feed rollers 123, 124, 125, and then supplies the paper P to the image forming unit 3 at a predetermined timing.

  The paper feeding unit 2 further includes a manual feed tray (not shown) and a pickup roller 127 that are attached to the left side surface of the device main body 1a shown in FIG. The pickup roller 127 takes out the paper P placed on the manual feed tray. The paper P taken out by the pickup roller 127 is sent out to the paper transport path by the paper feed rollers 123 and 125, and is supplied to the image forming unit 3 by the registration roller 126 at a predetermined timing.

  The image forming unit 3 includes an image forming unit 7, an intermediate transfer belt 31 on which a toner image based on image data transmitted from a computer or the like to the surface (contact surface) of the image forming unit 7 is primarily transferred. A secondary transfer roller 32 is provided for secondary transfer of the toner image on the intermediate transfer belt 31 onto the paper P fed from the paper feed cassette 121.

The image forming unit 7 includes a black unit 7K, a yellow unit 7Y, a cyan unit 7C, and a magenta unit 7M which are sequentially arranged from the upstream side (right side in FIG. 3) to the downstream side. ing. In each of the units 7K, 7Y, 7C and 7M, a drum-type electrophotographic photosensitive member 37 as an image carrier is arranged at the center position so as to be rotatable in the direction of an arrow (clockwise). Around each electrophotographic photosensitive member 37, a charging roller 39, an exposure unit 38, a developing unit 71, a cleaning unit (not shown), a static eliminator, and the like are sequentially arranged from the upstream side in the rotation direction.

  The charging roller 39 uniformly charges the peripheral surface of the electrophotographic photosensitive member 37 rotated in the direction of the arrow. In the charging unit including the charging roller 39, when an organic photoconductor is used as the electrophotographic photoconductor that is an image carrier, the wear amount of the photosensitive layer tends to increase. Therefore, the charging roller 39 can be used, and advantages such as reduction of ozone generation during charging can be utilized.

The exposure unit 38 is a so-called laser scanning unit, and laser light based on image data input from a personal computer (PC) as a host device on the peripheral surface of the electrophotographic photosensitive member 37 uniformly charged by the charging roller 39. To form an electrostatic latent image on the electrophotographic photoreceptor 37 based on the image data. The developing unit 71 supplies toner to the peripheral surface of the electrophotographic photosensitive member 37 on which the electrostatic latent image is formed, thereby forming a toner image based on the image data. The toner image is primarily transferred to the intermediate transfer belt 31. The cleaning unit cleans the toner remaining on the peripheral surface of the electrophotographic photosensitive member 37 after the primary transfer of the toner image to the intermediate transfer belt 31 is completed. The static eliminator neutralizes the peripheral surface of the electrophotographic photosensitive member 37 after the primary transfer is completed. The peripheral surface of the electrophotographic photosensitive member 37 cleaned by the cleaning unit and the charge eliminator goes to the charging unit for a new charging process, and a new charging process is performed.

  The intermediate transfer belt 31 is an endless belt-like rotating body, and includes a driving roller 33, a driven roller 34, a backup roller 35, and a front surface (contact surface) side in contact with the peripheral surface of each electrophotographic photosensitive member 37. And a plurality of rollers such as the primary transfer roller 36. The intermediate transfer belt 31 is configured to rotate endlessly by a plurality of rollers in a state where the intermediate transfer belt 31 is pressed against the electrophotographic photosensitive member 37 by a primary transfer roller 36 disposed opposite to each electrophotographic photosensitive member 37. . The driving roller 33 is rotationally driven by a driving source such as a stepping motor, and gives a driving force for rotating the intermediate transfer belt 31 endlessly. The driven roller 34, the backup roller 35, and the primary transfer roller 36 are rotatably provided, and are driven to rotate with the endless rotation of the intermediate transfer belt 31 by the driving roller 33. These rollers 34, 35, 36 are driven to rotate via the intermediate transfer belt 31 in accordance with the main rotation of the drive roller 33 and support the intermediate transfer belt 31.

  The primary transfer roller 36 applies a primary transfer bias (a polarity opposite to the toner charging polarity) to the intermediate transfer belt 31. By doing so, the toner image formed on each electrophotographic photosensitive member 37 is moved between each electrophotographic photosensitive member 37 and the primary transfer roller 36 by driving the driving roller 33 (counterclockwise). The images are sequentially transferred (primary transfer) in an overcoated state to the intermediate transfer belt 31 that circulates in the direction.

  The secondary transfer roller 32 applies a secondary transfer bias having a polarity opposite to that of the toner image to the paper P. By doing so, the toner image primarily transferred onto the intermediate transfer belt 31 is transferred to the paper P between the secondary transfer roller 32 and the backup roller 35, and thereby, a color transfer image ( An unfixed toner image) is transferred.

  The fixing unit 4 performs a fixing process on the transfer image transferred to the paper P by the image forming unit 3. The fixing unit 4 is disposed opposite to the heating roller 41 heated by the energized heating element, and is disposed on the circumferential surface. Is provided with a pressure roller 42 pressed against and contacted with the peripheral surface of the heating roller 41.

  Then, the transfer image transferred to the paper P by the secondary transfer roller 32 in the image forming unit 3 is subjected to fixing processing by heating when the paper P passes between the heating roller 41 and the pressure roller 42. To be established. The paper P subjected to the fixing process is discharged to the paper discharge unit 5. Further, in the color printer 1 of the present embodiment, a transport roller 6 is disposed at an appropriate position between the fixing unit 4 and the paper discharge unit 5.

  The paper discharge unit 5 is formed by recessing the top of the apparatus main body 1a of the color printer 1, and a paper discharge tray 51 for receiving the discharged paper P is formed at the bottom of the concave portion. .

  The color printer 1 forms an image on the paper P by the image forming operation as described above. In the tandem type image forming apparatus as described above, the above-described electrophotographic photosensitive member is provided as an image carrier, and the above-described toner is used as toner supplied from the developing unit. Therefore, a charging roller is provided as a charging unit. Even in this case, it is possible to form an image suitable for suppressing the occurrence of image defects while suppressing the wear of the photosensitive member, and to obtain an image forming apparatus having excellent durability and image quality.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by the Example.

[Example 1]
By the following method, an undercoat layer and a photosensitive layer were formed in this order on a conductive substrate to prepare a photoreceptor.
(Formation of undercoat layer)
After surface treatment with alumina and silica, 2 parts by mass of titanium oxide (manufactured by Teika Co., Ltd., SMT-A (prototype), number average primary particle size 10 nm) surface-treated with methyl hydrogen polysiloxane by wet dispersion; , 6, 12, 66, 610 quaternary copolymerized polyamide resin (Amilan CM8000, manufactured by Toray Industries, Inc.) using a solvent consisting of 10 parts by mass of methanol, 1 part by mass of butanol, and 1 part by mass of toluene. Then, a coating solution for the undercoat layer was prepared by dispersing for 5 hours using a bead mill.

  The obtained undercoat layer coating solution was filtered through a filter having an opening of 5 μm, and then the undercoat layer coating solution was applied by dip coating on a conductive substrate made of an aluminum drum having a diameter of 30 mm and a total length of 246 mm. After application of the coating solution, it was treated at 130 ° C. for 30 minutes to form an undercoat layer having a thickness of 1.5 μm on the conductive substrate.

(Formation of photosensitive layer)
1.5 parts by weight of titanyl phthalocyanine (charge generating agent), 1 part by weight of polyvinyl butyral resin (base resin, Denka Butyral # 6000C), 40 parts by weight of propylene glycol monomethyl ether and 40 parts by weight of tetrahydrofuran The dispersion medium consisting of the above was mixed and dispersed for 2 hours by a bead mill to prepare a charge generation layer coating solution. The obtained coating solution for charge generation layer was filtered with a filter having an opening of 3 μm, and then the coating solution for charge generation layer was applied on the undercoat layer by a dip coating method. After application of the coating solution, it was treated at 50 ° C. for 5 minutes to form a charge generation layer having a thickness of 0.3 μm.

  Next, 40 parts by mass of hole transport agent (HTM-1), 2 parts by mass of electron transport agent (ETM-1), 80 parts by mass of binder resin I (Resin-1, viscosity average molecular weight 51,000), and binder resin II 20 parts by mass (Resin-6, viscosity average molecular weight 49,000) was dissolved in a solvent comprising 500 parts by mass of tetrahydrofuran and 200 parts by mass of toluene to prepare a coating solution for a charge transport layer.

The obtained charge transport layer coating solution was applied onto the charge generation layer in the same manner as the charge generation layer, and then treated at 120 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm.

(Toner preparation example)
As resin, polyester resin (number average molecular weight Mn = 3700, glass transition temperature Tg = 62 ° C.) 100 parts by mass, charge control agent (salicylic acid metal complex, Bontron E-84, manufactured by Orient Chemical Industry Co., Ltd.) 1.2 parts by mass, 4.0 parts by weight of coloring agent (Pigment Blue 15: 3 [ECB-301], manufactured by Dainichi Seika Kogyo Co., Ltd.), and release agent (hydroxy acid ester wax, Carnauba wax No. 1 powder, melting point 83 ° C., 5.0 parts by mass of Yoko Kato) was mixed using a Henschel mixer. The obtained mixture was melt-kneaded with a twin screw extruder, cooled, and coarsely pulverized with a cutter mill having a screen with a diameter of 2 mm, and then a collision plate type pulverizer (dispersion separator, manufactured by Nippon Pneumatic Industry Co., Ltd.) was used. The toner base particles were obtained by pulverization and classification using an air classifier.

  The average particle diameter of the obtained toner base particles obtained by measuring 30000 counts with an aperture diameter of 100 μm using a cell counting analyzer (Coulter Multisizer 3, manufactured by Beckman Coulter, Inc.) was 4.0 μm.

  To 100 parts by mass of the obtained toner base particles, 2.5 parts by mass of hydrophobic silica (R972, manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter: 16 nm) was added, and the rotation was 3000 rpm using a Henschel mixer with a capacity of 10 L. The mixture was stirred for 5 minutes at a rotation speed of minutes and then cooled. The process of cooling after stirring for 5 minutes was repeated a total of 5 times (total stirring time of 25 minutes) to obtain a toner.

[Examples 2 to 14 and Comparative Examples 1 to 3 ]
A photoconductor was formed in the same manner as in Example 1 except that the types and amounts used of the hole transport agent (HTM), binder resin I, and binder resin II were changed to the types and amounts used in Table 1. . Further, a toner was prepared in the same manner as in Example 1 except that the amount of silica used was changed to the amount shown in Table 1 and the type of wax was changed to the type shown in Table 1. In Example 14, the pulverization time and classification conditions were adjusted to obtain a toner having a particle size of 6.5 μm.

  In Examples and Comparative Examples, HTM-1 to HTM-3 represented by the following formula were used as hole transport agents, and ETM-1 represented by the following formula was used as an electron transport agent. Moreover, Resin-1 to Resin-6 composed of repeating units represented by the following formulas were used as the binder resin I and the binder resin II.

[Hole transport agent]

[Electron transport agent]

[Binder resin]

In the examples and comparative examples, the following waxes were used as mold release agents.
WAX-1: hydroxy acid ester wax (carnauba wax No. 1 powder, melting point 83 ° C.)
WAX-2: Paraffin wax (C40 paraffin, manufactured by Wako Pure Chemical Industries, Ltd., melting point 83 ° C.)

[Evaluation of film thickness change, image defects, and appearance of photoreceptor surface]
The electrophotographic photoreceptors prepared in Examples and Comparative Examples were mounted on a commercially available printer that employs a negatively charged reversal development process and provided with a charging roller. Next, the toner cartridge (color: cyan) whose interior is cleaned is filled with the toner manufactured in the example and the comparative example, and the toner cartridge filled with the toner is set in the printer. Changes in thickness, occurrence of image defects, and changes in the appearance of the photoreceptor surface were evaluated. Table 1 shows the evaluation results of changes in film thickness, occurrence of image defects, and changes in the appearance of the photoreceptor surface.

<Thickness change measurement method>
Using A4 size paper, 10,000 blank sheets were continuously printed in a room temperature environment, and the change in film thickness of the photosensitive layer before and after printing was measured.

<Image evaluation>
The case where there was no image defect when a solid image was output was marked with ◯, and the case where an image defect occurred was marked with x. For the image evaluation, a solid image (100%) was printed on the entire surface of A4 paper, and judged visually. The case where there were 10 or more dash marks with a length of 0.8 mm or more in the longitudinal direction of the image was taken as x.

<Appearance evaluation>
The case where the toner component did not adhere to the surface of the photoconductor was marked as ◎, the case where the toner component was slightly adhered was marked as ○, and the case where a large amount of toner component was adhered was marked as x.
Specifically, the number of dash marks is calculated at five locations (41 mm, 82 mm, 123 mm, 164 mm, and 205 mm from the top of the drum) by dividing the surface of the photoconductor (2 mm × 2 mm) into six equal distances in the drum axis direction. The appearance was evaluated by observing with an optical microscope. Regarding the average number of five locations, the case where the number of dash marks was 10 or less was marked with ◎, the case where it was 50 or less, ○, and the case where it exceeded 50, ×.

＊表１中、バインダ樹脂に関する部数は質量部を意味する。

* In Table 1, the number of parts related to the binder resin means parts by mass.

  From Table 1, Example 1 is provided with a photoreceptor in which the content of silica in the toner is 2.5% by mass or more and 6.0% by mass or less, and a polycarbonate resin containing the binder resin I is used as the binder resin of the photosensitive layer. When the image forming apparatus of ˜13 is used, it can be seen that there is little change in the film thickness of the photoconductor, image defects are less likely to occur, and no toner component adheres to the photoconductor surface.

  In the image forming apparatus of Comparative Example 1 in which the silica content in the toner is less than 2.5% by mass, the change in the film thickness of the photoconductor is small, and adhesion of the toner component to the surface of the photoconductor was not observed. An abnormal image density occurred.

  In the image forming apparatus of Comparative Example 2 in which the silica content in the toner exceeds 6.0% by mass, the change in the film thickness of the photoconductor is small, but the toner component easily adheres to the surface of the photoconductor and adheres to the surface of the photoconductor. Dash marks were generated due to the toner component.

  In the image forming apparatus of Comparative Example 3 using a resin that does not contain the binder resin I as the binder resin of the photoconductor, image defects are less likely to occur and toner component adhesion to the surface of the photoconductor is small. There was significant wear on the layer.

DESCRIPTION OF SYMBOLS 10 Laminated-type photoreceptor 10 'Laminated-type photoreceptor which has an undercoat layer 11 Conductive substrate 12 Charge generation layer 13 Charge transport layer 14 Undercoat layer 20 Single-layer type photoreceptor 20' Single-layer-type photoreceptor which has an undercoat layer 21 Photosensitive layer

Claims (6)

Image forming comprising: an electrophotographic photosensitive member as an image bearing member; a developing unit using toner containing at least a resin, a colorant, a release agent, and silica; and a charging roller that applies a voltage to the surface of the electrophotographic photosensitive member. A device,
The electrophotographic photoreceptor has a photosensitive layer formed on a conductive substrate,
The photosensitive layer is
1) a photosensitive layer in which a charge generation layer containing at least a charge generation agent, a charge transport layer containing at least a charge transfer agent and a binder resin are sequentially laminated, or
2) A photosensitive layer containing at least a charge generator, a charge transport agent, and a binder resin,
The binder resin comprises only a copolymer polycarbonate resin selected from copolymer polycarbonate resins represented by the following general formulas (I-1) to (I- 4 ) and a repeating unit represented by the following formula (II). Including polycarbonate resin,
The content of the copolymer polycarbonate resin selected from the copolymer polycarbonate resins represented by the general formulas (I-1) to (I-4) in the binder resin is represented by the formula (II). 2 to 30 times by mass based on the content of polycarbonate resin consisting only of repeating units,
An image forming apparatus, wherein the content of silica in the toner is 2.5% by mass or more and 6% by mass or less in the mass of the toner.

[In formulas (I-1) to ( 1-4 ), n + m = 1, and 0.35 ≦ m <0.7. ]

  The image forming apparatus according to claim 1, wherein the toner has an average particle diameter of 4.5 to 6.5 μm.   The image forming apparatus according to claim 1, wherein the release agent is a hydroxy acid ester wax.   The image forming apparatus according to claim 1, wherein the resin in the toner is a polyester resin. Wherein the photosensitive member, the content of the charge transport agent, characterized in that with respect to the binder resin 100 parts by mass or less 55 parts by mass, claim 1-4 image forming apparatus according to any one. Wherein the photosensitive member, the charge transport agent, characterized in that a compound represented by the following general formula (III) or the following general formula (IV), the image forming apparatus according to any one of claims 1-5.

[In Formula (III), R ^{9 to} R ¹⁵ are each independently a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, and two adjacent groups selected from R ^{11 to} R ¹⁵ are bonded to each other. To form a ring. a represents an integer of 0 to 5. ]

[In Formula (IV), R ^{16 to} R ²³ are each independently a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group. b represents an integer of 0 to 5, c represents an integer of 0 to 4, and k represents 0 or 1. ]

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