JP6540149B2 - Image forming device - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus.

In the electrophotographic image forming apparatus, the surface of the photosensitive member is uniformly charged and then exposed to form an electrostatic latent image, and the electrostatic latent image is developed with toner to form a toner image. The toner image is electrostatically transferred to a transfer material and then fixed to form an image.
In the transfer step of electrostatically transferring the toner image to the transfer material, the transfer current flowing to the photosensitive member rather than the image portion where the toner is attached to the non-image portion where the toner is not attached on the surface of the photosensitive member As a result, the charging characteristics and the potential after exposure between the image area and the non-image area on the surface of the photosensitive member differ from each other, resulting in the generation of a transfer memory. There is a problem of

  After the toner image is formed on the surface of the photosensitive member for the purpose of solving the problem of the transfer memory or for obtaining the separation property of the transfer material, the photosensitive member may be There is known a technique for reducing the potential difference between the image area and the non-image area by exposing the surface and removing the charge (for example, see Patent Documents 1 to 8).

However, depending on various conditions of the image forming process, there is a problem that scattering of toner occurs at the time of transfer due to charge removal before transfer, and there may also be an adverse effect on transfer memory.
Such a problem can be solved by providing a new control unit in the image forming apparatus or the like, but a new problem such as complication of the process arises.

JP 2014-26144 A JP, 2011-221405, A JP, 2013-156486, A JP, 2010-197744, A Unexamined-Japanese-Patent No. 11-167293 gazette JP 2003-295626 A Unexamined-Japanese-Patent No. 2010-175593 Unexamined-Japanese-Patent No. 2010-101986

  The present invention has been made in consideration of the above circumstances, and an object thereof is to provide an image forming apparatus capable of suppressing both the generation of a transfer memory and the generation of toner scattering at the time of transfer. It is.

In the image forming apparatus according to the present invention, charging means for charging the surface of the photosensitive member along the rotational direction of the photosensitive member in the outer peripheral surface region of the rotating photosensitive member, and the photosensitive member charged by the charging means are exposed Exposure means, developing means for supplying toner to the photosensitive member exposed by the exposure means to form a toner image, charge removal means for pre-transfer to charge and remove the surface of the photosensitive member, and the photosensitive member And transfer means for transferring the toner image of
The pre-transfer charge removing unit is configured such that a potential Va of a portion (non-image portion) to which no toner is attached in the toner image formed by the developing portion and a surface of the portion (image portion) over the toner The charge is removed under the condition that the potential Vb is VaVaVb,
The outermost surface layer of the photosensitive member is characterized by comprising a protective layer comprising a charge transfer agent contained in a cured resin obtained by subjecting a crosslinkable polymerizable compound to a polymerization reaction.

  In the image forming apparatus of the present invention, the charge transfer agent is preferably a compound represented by the following general formula (1).

[In the general formula ^{(1), R 1, R} 2, R 3 and R ⁴ each independently represents an alkyl group or an alkoxy group having 1 to 7 carbon atoms having 1 to 7 carbon atoms. k, l and n each represent an integer of 0 to 5, and m represents an integer of 0 to 4. However, when k, l, n or m is 2 or more, plural R ¹ , R ² , R ³ or R ⁴ may be the same as or different from each other . ]

  In the image forming apparatus of the present invention, the protective layer preferably further contains inorganic fine particles.

  According to the image forming apparatus of the present invention, a photosensitive member having a protective layer comprising a charge transport agent contained in a cured resin obtained by polymerizing a crosslinkable polymerizable compound is provided, and the photosensitive member By providing the pre-transfer charge-removing means for exposing the surface of the light source to discharge the charge, it is possible to suppress both the generation of the transfer memory and the generation of the toner scattering during the transfer.

FIG. 2 is a cross-sectional view for illustrating the configuration of an example of the image forming apparatus of the present invention.

  Hereinafter, the present invention will be described in detail.

[Image forming apparatus]
In the image forming apparatus of the present invention, charging means for charging the surface of the photosensitive member and exposure for exposing the photosensitive member charged by the charging means along the rotational direction of the photosensitive member in the outer peripheral surface region of the rotating photosensitive member Means, developing means for supplying toner to the photosensitive member exposed by the exposing means to form a toner image, pre-transfer charge removing means for exposing and removing the surface of the photosensitive member, and toner formed on the photosensitive member A transfer means for transferring an image to a transfer material is sequentially arranged.

[Photoreceptor]
The photosensitive member provided in the image forming apparatus of the present invention is an organic photosensitive member having a layer structure in which an organic photosensitive layer comprising a charge generating layer and a charge transporting layer and a protective layer are sequentially laminated on a conductive support. is there. In the photoreceptor, an intermediate layer may be provided between the conductive support and the charge generation layer. Also, the organic photosensitive layer may be a single layer containing a charge generating substance and a charge transporting substance.

  In the present invention, an organic photoreceptor refers to a photoreceptor having an organic compound having at least one of the charge generation function and the charge transport function which are essential for the construction of the photoreceptor, and known organic charge generation substances or organic charge transport A known organic photoreceptor such as a photoreceptor composed of a substance, a photoreceptor having a charge generation function and a charge transport function composed of a polymer complex, and the like is included.

[Protective layer]
The protective layer constituting the photosensitive member according to the present invention is formed as the outermost surface layer on the organic photosensitive layer. The protective layer is a crosslinkable cured resin obtained by subjecting a crosslinkable polymerizable compound to a polymerization reaction to contain a charge transport agent, and preferably further contains inorganic fine particles.
According to the protective layer formed of the crosslinkable cured resin, the life of the photosensitive member can be extended.

(Curing resin)
The cured resin constituting the protective layer is obtained by polymerizing and curing a crosslinkable polymerizable compound by irradiation of actinic radiation such as ultraviolet light and electron beam. As the polymerizable compound, a monomer (polyfunctional polymerizable compound) having two or more polymerizable functional groups can be used in combination with a monomer (monofunctional polymerizable compound) having one polymerizable functional group. Specifically, examples of the polymerizable compound include styrene monomers, acrylic monomers, methacrylic monomers, vinyl toluene monomers, vinyl acetate monomers, N-vinylpyrrolidone monomers, and the like.

An acrylic monomer having two or more acryloyl groups (CH ₂ CHCHCO—) or methacryloyl groups (CH ₂ CCCH ₃ CO—) as a polymerizable compound, which can be cured in a small amount of light or in a short time. Or those oligomers are particularly preferred.

  In the present invention, the polymerizable compounds may be used alone or in combination. Moreover, although these polymerizable compounds may use a monomer, you may oligomerize and use them.

  Hereafter, the specific example of a polymeric compound is shown.

However, in the chemical formula shown above exemplary compound (M1) ~ (M14), R represents an acryloyl group _{(CH 2 = CHCO-), R} ' represents a methacryloyl group _{(CH 2 = CCH 3 CO-)} .

  As the polymerizable compound, it is preferable to use a monomer having three or more polymerizable functional groups. As the polymerizable compound, two or more compounds may be used in combination, but also in this case, it is preferable to use a monomer having three or more polymerizable functional groups in a proportion of 50% by mass or more.

(Charge transport agent)
The charge transport agent contained in the protective layer is one having charge transportability for transporting charge carriers in the protective layer.
As the charge transport agent, a compound represented by the above general formula (1) (hereinafter, also referred to as “specific charge transport agent”) can be used.
Many compounds represented by the above general formula (1) do not show absorption in a short wavelength region, and many of them have a molecular weight of 450 or less, and can enter voids of a cured resin constituting a protective layer. For this reason, it is possible to smoothly inject charge carriers from the charge transport layer without reducing the scratch resistance of the protective layer, and to transport charges to the surface of the protective layer without causing generation of transfer memory. Can. As the specific charge transporting agent, it is particularly preferable to use one having a molecular weight of 320 or more and 420 or less.

In the general formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 7 carbon atoms, and k, l and n each represent The integer of 0-5 and m show the integer of 0-4. However, when k, l, n or m is 2 or more, plural R ¹ , R ² , R ³ or R ⁴ may be the same as or different from each other .
When R ¹ , R ² , R ³ or R ⁴ is an alkyl group, the alkyl group may be linear or branched and may have 1 to 5 carbon atoms. It is more preferable that it is a linear alkyl group.
Further, R ¹ and R ² are preferably different from each other from the viewpoint of the production stability of the protective layer.

  Examples of the alkyl group having 1 to 7 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group and n-hexyl group Group, 3-methylpentan-2-yl group, 3-methylpentan-3-yl group, 4-methylpentyl group, 4-methylpentan-2-yl group, 1,3-dimethylbutyl group, 3, 3- Dimethylbutyl, 3,3-dimethylbutan-2-yl, n-heptyl, 1-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1-ethylpentyl 1- (n-propyl) butyl group, 1,1-dimethylpentyl group, 1,4-dimethylpentyl group, 1,1-diethylpropyl group, 1,3,3-trimethylbutyl group Groups, such as 1-ethyl-2,2-dimethyl propyl group. Among these, an alkyl group having 1 to 5 carbon atoms is more preferable, and a methyl group, an ethyl group, a propyl group, an n-butyl group and an n-pentyl group are more preferable.

  As a C1-C7 alkoxy group, a methoxy group, an ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, n-pentyloxy group, Isopentyloxy group, neopentyloxy group, 1,2-dimethyl-propoxy group, n-hexyloxy group, 3-methylpentan-2-yloxy group, 3-methylpentan-3-yloxy group, 4-methylpentyloxy Group, 4-methylpentan-2-yloxy group, 1,3-dimethylbutyloxy group, 3,3-dimethylbutyloxy group, 3,3-dimethylbutan-2-yloxy group, n-heptyloxy group, 1- Methylhexyloxy group, 3-methylhexyloxy group, 4-methylhexyloxy group, 5-methylhexyl oxy Group, 1-ethylpentyloxy group, 1- (n-propyl) butyloxy group, 1,1-dimethylpentyloxy group, 1,4-dimethylpentyloxy group, 1,1-diethylpropyloxy group, 1,3, 3-trimethylbutyloxy group, 1-ethyl-2, 2-dimethylpropyloxy group etc. are mentioned. Among these, a C1-C2 alkoxy group is more preferable, and a methoxy group is more preferable.

In particular, at least one of R ¹ , R ² , R ³ and R ⁴ preferably has a propyl group, a butyl group or a pentyl group.

Furthermore, it is more preferable that R ¹ and R ² each be a hydrogen atom or a methyl group. Furthermore, R ³ is a hydrogen atom, more preferably R ⁴ is an alkyl group having 1 to 5 carbon atoms. More preferably, k, l, m and n are each 1.

  Hereafter, the specific example of a compound represented by the said General formula (1) is shown.

  However, in the chemical formulas showing the above exemplified compounds (CTM-9) to (CTM-11), Me represents a methyl group.

  The compound represented by General formula (1) can be synthesize | combined by the well-known synthetic | combination method, for example, the method disclosed, such as Unexamined-Japanese-Patent No. 2006-143720.

  As the charge transport agent contained in the protective layer, in addition to a specific charge transport agent, a compound represented by the following formula (A) can also be used.

  As the charge transport agent contained in the protective layer, it is preferable to use a compound represented by the above formula (CTM-13) or a compound represented by the above formula (A), and a table by the above formula (CTM-13) It is particularly preferred to use the following compounds.

(Inorganic fine particles)
As the inorganic fine particles contained in the protective layer, it is preferable to use conductive inorganic fine particles, and for example, metal oxide fine particles can be used. Examples of metal oxide particles include silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), zirconium oxide, tin oxide, titania (titanium oxide), niobium oxide, molybdenum oxide, vanadium oxide Although what can consist of etc. can be used, it is preferable to use what consists of tin oxides especially from a viewpoint of an electrical property.
The metal oxide fine particles are not particularly limited, and particles produced by a known production method can be used.

  The number average primary particle size of the inorganic fine particles is preferably 1 to 300 nm, more preferably 3 to 100 nm, and still more preferably 5 to 40 nm.

  In the present invention, the number average primary particle diameter of the inorganic fine particles is a photographic image obtained by taking a magnified image of 10000 times with a scanning electron microscope (manufactured by Nippon Denshi) and randomly capturing 300 particles by a scanner (aggregated particles The number average primary particle size was calculated using an automatic image processing and analyzing apparatus "LUZEX AP (software version Ver.1.32)" (manufactured by Nireko Co., Ltd.).

The inorganic fine particles may be surface-treated with a surface treatment agent having a reactive organic group (hereinafter, also referred to as a “reactive organic group-containing surface treatment agent”). Specifically, reactive organic groups are formed on the surface of the untreated inorganic fine particles by surface-treating the inorganic fine particles (hereinafter also referred to as "untreated inorganic fine particles") as the raw material with the reactive organic group-containing surface treatment agent. Was introduced.
As the reactive organic group-containing surface treatment agent, those which react with hydroxy groups and the like present on the surface of untreated inorganic fine particles are preferable. As such a reactive organic group-containing surface treatment agent, for example, a silane coupling agent And titanium coupling agents.
Moreover, as the reactive organic group-containing surface treatment agent, it is preferable to use a surface treatment agent having a radically polymerizable reactive group. As a radically polymerizable reactive group, a vinyl group, an acryloyl group, a methacryloyl group etc. are mentioned, for example. Such a radically polymerizable reactive group can also react with the polymerizable compound according to the present invention to form a strong protective layer. As the surface treating agent having a radically polymerizable reactive group, a silane coupling agent having a radically polymerizable reactive group such as a vinyl group, an acryloyl group or a methacryloyl group is preferable.

  Hereinafter, specific examples of the reactive organic group-containing surface treatment agent are shown below.

_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl ₃
S-4: CH ₂ CHCHCOO (CH ₂ ) ₂ Si (CH ₃ ) (OCH ₃ ) _{2
S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
S-6: CH ₂ = CHCOO (CH ₂ ) ₂ Si (OC ₂ H ₅ ) (OCH ₃ ) ₂
S-7: CH ₂ = CHCOO (CH ₂ ) ₃ Si (OCH ₃ ) ₃
S-8: CH ₂ = CHCOO (CH ₂ ) ₂ Si (CH ₃ ) Cl _{2
S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
_{S-11: CH 2 = CHCOO} (CH 2) 3 SiCl 3
_{S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
S-14: CH ₂ CC (CH ₃ ) COO (CH ₂ ) ₃ Si (CH ₃ ) (OCH ₃ ) ₂
S-15: CH ₂ CC (CH ₃ ) COO (CH ₂ ) ₃ Si (OCH ₃ ) ₃
S-16: CH ₂ CC (CH ₃ ) COO (CH ₂ ) ₂ Si (CH ₃ ) Cl _{2
S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
S-19: CH ₂ CC (CH ₃ ) COO (CH ₂ ) ₃ SiCl _{3
S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
S-24: CH ₂ CC (CH ₃ ) Si (CH ₃ ) (OCH ₃ ) _{2
S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
S-28: CH ₂ CC (CH ₃ ) COOSi (OCH ₃ ) ₃
S-29: CH ₂ = C (CH ₃ ) COOSi (OC ₂ H ₅ ) _{3
S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2

  In addition, as the reactive organic group-containing surface treatment agent, a silane compound having a reactive organic group capable of radical polymerization may be used other than the compounds shown in the above exemplified compounds (S-1) to (S-36). .

  The reactive organic group-containing surface treatment agent may be used alone or in combination of two or more.

  The amount of the reactive organic group-containing surface treatment agent used is preferably 0.1 to 200 parts by mass, and more preferably 7 to 70 parts by mass, with respect to 100 parts by mass of the untreated inorganic fine particles.

  As a processing method for the untreated inorganic fine particles of the reactive organic group-containing surface treatment agent, for example, a slurry (suspension of solid particles) containing the untreated inorganic fine particles and the reactive organic group-containing surface treatment agent is wet-crushed Methods are included. By this method, the surface treatment of the untreated inorganic fine particles proceeds while preventing the reaggregation of the untreated inorganic fine particles. Thereafter, the solvent is removed and powdered.

  As a surface treatment apparatus, a wet media dispersion type apparatus is mentioned, for example. In this wet media dispersion type apparatus, beads are packed as media in a container, and further, by rotating an agitation disk mounted vertically to a rotating shaft at high speed, agglomerated particles of untreated inorganic fine particles are crushed, crushed and dispersed. It is an apparatus having a process, and the configuration thereof is not limited as long as the untreated inorganic fine particles can be sufficiently dispersed and surface treated when surface-treating, for example, vertical type Various types such as horizontal type, continuous type and batch type can be adopted. Specifically, sand mills, ultravisco mills, pearl mills, grain mills, dyno mills, agitator mills, dynamic mills, etc. can be used. These dispersion-type devices are pulverized and dispersed by impact crushing, friction, shear, shear stress and the like using grinding media such as balls and beads.

  As the beads used in the wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone or the like as a raw material can be used, but those made of zirconia or zircon are particularly preferable. Moreover, as a size of a bead, although a thing about diameter 1-2 mm is usually used, it is preferable to use a thing about 0.1-1.0 mm in this invention.

  Although various materials such as stainless steel, nylon, ceramic and the like can be used for the disk and the inner wall of the container used in the wet media dispersion type device, the ceramic disk and the inner wall of the container such as zirconia or silicon carbide are particularly used in the present invention. Is preferred.

  The protective layer may contain other components in addition to the curable resin, the specific charge transport agent and the inorganic fine particles, and for example, various antioxidants may be contained, and various lubricant particles are added. It can also be done. As lubricant particles, for example, fluorine atom-containing resin particles can be added. The fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorochlorinated ethylene resin, hexafluorochlorinated ethylene-propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluoride dichloride ethylene resin, and the like It is preferable that it consists of what was suitably selected 1 type, or 2 or more types out of a copolymer, However, It is preferable to be what consists of tetrafluoroethylene resin and vinylidene fluoride resin especially.

  The thickness of the protective layer is preferably 0.2 to 10 μm, and more preferably 0.5 to 6 μm.

  Hereinafter, the configuration of the photosensitive member other than the protective layer will be described.

[Conductive Support]
The conductive support may be any conductive support, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel molded into a drum or sheet, or a metal foil such as aluminum or copper What is laminated on a plastic film, that on which aluminum, indium oxide, tin oxide or the like is vapor-deposited on a plastic film, metals provided with a conductive layer by applying a conductive substance alone or together with a binder resin, plastic films and paper .

[Intermediate layer]
In the photoreceptor, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive support and the organic photosensitive layer. It is preferable to provide an intermediate layer in consideration of various failure prevention and the like.

  Such an intermediate layer contains, for example, a binder resin (hereinafter, also referred to as “intermediate layer binder resin”) and, if necessary, conductive particles and metal oxide particles.

  Examples of the intermediate layer binder resin include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, gelatin and the like. Among these, alcohol-soluble polyamide resins are preferred.

The intermediate layer can contain various conductive particles and metal oxide particles for the purpose of adjusting resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide can be used. Ultrafine particles of tin-doped indium oxide, antimony-doped tin oxide and zirconium oxide can be used.
The number primary average particle diameter of such metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  These metal oxide particles may be used alone or in combination of two or more. When two or more are mixed, they may be in the form of solid solution or fusion.

  The content ratio of the conductive particles or the metal oxide particles is preferably 20 to 400 parts by mass, and more preferably 50 to 350 parts by mass with respect to 100 parts by mass of the intermediate layer binder resin.

  The thickness of the intermediate layer is preferably 0.1 to 15 μm, more preferably 0.3 to 10 μm.

[Charge generation layer]
The charge generation layer in the organic photosensitive layer contains a charge generation material and a binder resin (hereinafter, also referred to as a “charge generation layer binder resin”).

  Examples of the charge generating material include azo raw materials such as sudan red and diane blue, quinone pigments such as pyrene quinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, pyranthrone, diphthaloyl pyrene and the like. Although a ring quinone pigment, a phthalocyanine pigment, etc. are mentioned, it is not limited to these. Among these, polycyclic quinone pigments and titanyl phthalocyanine pigments are preferable. These charge generation materials may be used alone or in combination of two or more.

  A known resin can be used as the binder resin for the charge generation layer, and for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and copolymer resin containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resin, chloride Vinyl-vinyl acetate-maleic anhydride copolymer resin), poly-vinylcarbazole resin, etc. may be mentioned, but it is not limited thereto. Among these, polyvinyl butyral resin is preferable.

  The content ratio of the charge generation material in the charge generation layer is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin for charge generation layer.

  The layer thickness of the charge generation layer varies depending on the characteristics of the charge generation substance, the characteristics of the binder resin for the charge generation layer, the content ratio, etc., but it is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. is there.

[Charge transport layer]
The charge transport layer in the organic photosensitive layer contains a charge transport agent and a binder resin (hereinafter, also referred to as “a binder resin for charge transport layer”).

  Examples of the charge transport agent contained in the charge transport layer include triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds, butadiene compounds and the like as substances transporting charges (holes).

  The charge transport agent contained in the charge transport layer may be the same as or different from the charge transport agent contained in the protective layer.

  A known resin can be used as the binder resin for the charge transport layer, and polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic acid ester resin, styrene-methacrylic acid ester Although copolymer resin etc. are mentioned, polycarbonate resin is preferable. Further, polycarbonate resins of BPA (bisphenol A) type, BPZ (bisphenol Z) type, dimethyl BPA type, BPA-dimethyl BPA copolymer type and the like are preferable in view of anti-cracking, abrasion resistance and charging characteristics.

  The content ratio of the charge transport agent in the charge transport layer is preferably 10 to 500 parts by mass, and more preferably 20 to 250 parts by mass with respect to 100 parts by mass of the binder resin for charge transport layer.

  The layer thickness of the charge transport layer varies depending on the properties of the charge transport agent, the properties and the content of the binder resin for the charge transport layer, etc., but it is preferably 5 to 40 μm, more preferably 10 to 30 μm.

  In the charge transport layer, an antioxidant, an electronic conductive agent, a stabilizer, a silicone oil and the like may be added. As the antioxidant, those disclosed in JP-A-2000-305291, and as the electron conductive agent, disclosed in JP-A-50-137543, JP-A-58-76483, etc. are preferable.

[Method of manufacturing photoreceptor]
Specifically, such a photoreceptor can be manufactured through the following steps.
Step (1): A step of forming an intermediate layer by applying a coating solution for forming an intermediate layer on the outer peripheral surface of the conductive support and drying it.
Step (2): A step of forming a charge generation layer by applying a coating solution for forming a charge generation layer on the outer peripheral surface of the intermediate layer formed on the conductive support and drying it.
Step (3): A step of forming a charge transport layer by applying a coating solution for forming a charge transport layer on the outer peripheral surface of the charge generation layer formed on the intermediate layer and drying it.
Step (4): A step of forming a protective layer by applying a coating solution for forming a protective layer on the outer peripheral surface of the charge transport layer formed on the charge generation layer, polymerizing and curing it.

[Step (1): Formation of Intermediate Layer]
The intermediate layer is prepared by dissolving the intermediate layer binder resin in a solvent to prepare a coating solution (hereinafter, also referred to as “intermediate layer forming coating solution”), and, if necessary, conductive particles and metal oxide particles. After the dispersion, the coating solution can be applied to a constant film thickness on a conductive support to form a coating film, and the coating film can be formed by drying.
As a method of applying the coating liquid for forming an intermediate layer, for example, known methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, circular slide hopper method and the like The method is mentioned.
Although the drying method of a coating film can be suitably selected according to the kind of solvent, and film thickness, heat drying is preferable.

  As a solvent used in the formation process of an intermediate | middle layer, what disperse | distributes electroconductive fine particles and metal oxide particles favorably, and melt | dissolves the binder resin for intermediate | middle layers, especially a polyamide resin is preferable. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, and sec-butanol are excellent in the solubility and coating performance of the polyamide resin. preferable. In addition, as co-solvents that can be used in combination with the above-mentioned solvent to improve the storage stability and the dispersibility of particles and obtain a preferable effect, benzyl alcohol, toluene, methylene chloride, cyclohexanone, tetrahydrofuran and the like can be mentioned.

  The concentration of the intermediate layer binder resin in the intermediate layer forming coating solution is appropriately selected according to the layer thickness and production rate of the intermediate layer.

  As a dispersing means of the conductive particles and the metal oxide particles, an ultrasonic dispersing machine, a ball mill, a sand mill, a homomixer or the like can be used, but it is not limited thereto.

[Step (2): Formation of Charge Generating Layer]
In the charge generation layer, a charge generation substance is dispersed in a solution in which a binder resin for charge generation layer is dissolved in a solvent to prepare a coating liquid (hereinafter, also referred to as “coating liquid for forming charge generation layer”). The coating solution can be applied to a predetermined film thickness on the intermediate layer to form a coating, and the coating can be formed by drying.
As a method of applying a coating solution for forming a charge generation layer, known methods such as dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method, circular slide hopper method, etc. Method is mentioned.
Although the drying method of a coating film can be suitably selected according to the kind of solvent, and film thickness, heat drying is preferable.

  Examples of the solvent used to form the charge generation layer include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, t-butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, Examples include, but are not limited to, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine and the like.

  Examples of the means for dispersing the charge generating substance include, but are not limited to, an ultrasonic disperser, a ball mill, a sand mill, a homomixer and the like.

[Step (3): Formation of Charge Transport Layer]
The charge transport layer is prepared by dissolving a binder resin for charge transport layer and a charge transport agent in a solvent (hereinafter, also referred to as “coating liquid for forming charge transport layer”), and the coating solution is subjected to charge generation. It can be formed by applying a constant film thickness on a layer to form a coating, and drying the coating.
As a method of applying the coating liquid for charge transport layer formation, for example, known methods such as dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method and circular slide hopper method Method is mentioned.
Although the drying method of a coating film can be suitably selected according to the kind of solvent, and film thickness, heat drying is preferable.

  Examples of the solvent used to form the charge transport layer include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4 -Dioxane, 1,3-dioxolane, pyridine, diethylamine and the like, but it is not limited thereto.

[Step (4): Formation of Protective Layer]
The protective layer is also referred to as a coating solution (hereinafter, "coating solution for forming a protective layer") by adding a polymerizable compound, a charge transport agent, a polymerization initiator and, if necessary, inorganic fine particles and other components to a known solvent. And coating the coating liquid for forming a protective layer on the outer peripheral surface of the charge transport layer formed in the step (3) to form a coating film, and the coating film is dried. A protective layer can be formed by polymerizing and curing the polymerizable compound in the coating film by irradiating actinic radiation.

  As means for dispersing the inorganic fine particles in the protective layer-forming coating solution, an ultrasonic disperser, a ball mill, a sand mill, a homomixer or the like can be used, but the invention is not limited thereto.

  As the solvent used for forming the protective layer, any solvent can be used as long as it can dissolve or disperse the polymerizable compound, the charge transport agent and the inorganic fine particles, and examples thereof include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, Examples include, but are not limited to, pyridine and diethylamine.

  As a method of applying a coating solution for forming a protective layer, for example, known methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, circular slide hopper method and the like The method is mentioned.

  The coating film may be cured without being dried, but it is preferable to cure after being naturally dried or thermally dried.

  The drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably from room temperature to 180 ° C, particularly preferably from 80 to 140 ° C. The drying time is preferably 1 minute to 200 minutes, particularly preferably 5 minutes to 100 minutes.

  Examples of the method of reacting the polymerizable compound include a method of reacting by electron beam cleavage, a method of adding a radical polymerization initiator, and reacting by light and heat. As the radical polymerization initiator, any of a photopolymerization initiator and a thermal polymerization initiator can be used. Moreover, a photoinitiator and a thermal-polymerization initiator can also be used together.

  The radical polymerization initiator is preferably a photopolymerization initiator, and among them, an alkylphenone compound or a phosphine oxide compound is preferable. In particular, compounds having an α-hydroxyacetophenone structure or an acylphosphine oxide structure are preferable.

  Specific examples of the compound having an acylphosphine oxide structure are shown in the following formula (P1) and the following formula (P2).

  The polymerization initiator may be used alone or in combination of two or more.

  The addition ratio of the polymerization initiator is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of all the polymerizable compounds for forming a cured resin. .

  The cured resin is produced by irradiating the coating film with actinic radiation as a curing treatment to generate radicals for polymerization, and to form and cure crosslinks by intermolecular and intramolecular crosslink reactions. As the actinic radiation, ultraviolet light and electron beam are more preferable, and ultraviolet light is particularly preferable because it is easy to use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, flash (pulsed) xenon and the like can be used.
The irradiation conditions vary depending on the respective lamps, but the irradiation dose of actinic radiation is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² .
The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW to 3 kW.

  There is no particular limitation on the electron beam irradiation apparatus as an electron beam source, and in general, a curtain beam system capable of obtaining a large output at relatively low cost as an electron beam accelerator for such electron beam irradiation is effective. Used. The acceleration voltage at the time of electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary actinic radiation dose is preferably 0.1 seconds to 10 minutes, and more preferably 0.1 seconds to 5 minutes from the viewpoint of working efficiency.

  In the step of forming the protective layer, drying can be performed before and after irradiation with actinic radiation and during irradiation with actinic radiation, and the timing of drying can be appropriately selected by combining these.

[Image forming apparatus]
FIG. 1 is a cross-sectional view for explaining the configuration of an example of the image forming apparatus of the present invention.
This image forming apparatus is referred to as a tandem type color image forming apparatus, and includes four sets of image forming units 10Y, 10M, 10C, and 10Bk, an intermediate transfer member unit 7, a sheet feeding unit 21 and a fixing unit 24. Become. A document image reader SC is disposed on the top of the main body A of the image forming apparatus.

The four image forming units 10Y, 10M, 10C, and 10Bk are arranged along the rotational direction of the photosensitive drums 1Y, 1M, 1C, and 1Bk in the outer peripheral region of the drum-shaped photosensitive members 1Y, 1M, 1C, and 1Bk. The charging units 2Y, 2M, 2C, 2Bk, the exposure units 3Y, 3M, 3C, 3Bk, the developing units 4Y, 4M, 4C, 4Bk, and the pre-transfer charge removing units 9Y, 9M, 9C, 9Bk, which are sequentially arranged. It comprises primary transfer means consisting of primary transfer rollers 5Y, 5M, 5C and 5Bk, and cleaning means 6Y, 6M, 6C and 6Bk.
The image forming apparatus of the present invention uses, as the photosensitive members 1Y, 1M, 1C, and 1Bk, a photosensitive member having a protective layer formed by containing a charge transfer agent in the above-mentioned cured resin.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different from yellow, magenta, cyan, and black, respectively. Hereinafter, the image forming unit 10Y will be described in detail as an example.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive member 1Y to charge the surface of the photosensitive member 1Y. In this example, a corona discharge type charger is used.

  The exposure unit 3Y is a unit that performs exposure based on an image signal (yellow) on the photosensitive member 1Y to which a uniform potential is applied by the charging unit 2Y, and forms an electrostatic latent image corresponding to the yellow image. In addition, as this exposure means 3Y, an exposure apparatus composed of LEDs in which light emitting elements are arranged in an array in the axial direction of the photosensitive member 1Y and an imaging element, or an exposure apparatus using a laser optical system or the like is used. .

  The developing means 4Y is a means for supplying a toner onto the exposed photosensitive member 1Y to form a toner image, for example, a developing sleeve and a photosensitive member 1Y, which incorporates a magnet and holds and rotates a developer, and the developing member It consists of a voltage application device which applies a direct current and / or an alternating current bias voltage between the sleeve and the sleeve.

The pre-transfer charge removing means 9Y is a means for removing charges by irradiating the surface of the photosensitive members 1Y, 1M, 1C, 1Bk on which toner images are formed with exposure light, and can be used, for example, as the exposure means 3Y. The exposure apparatus mentioned can be used.
The wavelength of the exposure light relating to the diselectrification may be, for example, 780 nm, as long as it is a wavelength range having sensitivity to the charge generation material (CGM) contained in the charge generation layer.

In the pre-transfer static eliminator 9Y, the potential Va of the portion (non-image portion) of the developed toner image on the photosensitive member 1Y to which no toner is attached and the toner over the portion (image portion) to which toner is attached The pre-transfer static elimination is performed under the condition that the surface potential Vb of the above becomes Va ≧ Vb, that is, the condition that the potential difference | Va−Vb | after the static elimination becomes 0 [V] or more. By performing charge removal before transfer under such conditions, the occurrence of toner scattering can be prevented.
Furthermore, toners in the image areas of the first and second rotations were excluded assuming that the first and second rotations form a solid image at an arbitrary point on the photosensitive member 1Y without performing charge removal before transfer. Based on the surface potential excluding the toner in the first rotation image area than the potential difference of the surface potential and the surface potential Vb across the toner of the image area when the pre-transfer charge removal is performed under the condition Va = Vb It is preferable to carry out pre-transfer static elimination under the condition that the potential difference with the surface potential excluding the amount of potential is small. By performing charge removal before transfer under such conditions, generation of transfer memory can be reliably suppressed.

  The primary transfer roller 5Y is a means for transferring the toner image formed on the photosensitive member 1Y to the endless belt-like intermediate transfer member 70, and is disposed in contact with the intermediate transfer member 70.

  The cleaning means 6Y is a means for cleaning the non-transferred toner remaining after transfer onto the photosensitive member 1Y, and comprises, for example, a cleaning blade and a brush roller provided upstream of the cleaning blade.

  The fixing unit 24 includes, for example, a heat roller fixed by a heating roller provided with a heat source inside and a pressure roller provided in a pressure-contacted state so that a fixing nip portion is formed on the heating roller. One of the methods is mentioned.

  In the image forming apparatus, of the image forming unit 10Y, the photosensitive member 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are integrally supported to be provided as a process cartridge. It may be configured to be attachable to and detachable from the apparatus main body A via the guide means.

  The image forming units 10Y, 10M, 10C and 10Bk are arranged in tandem in the vertical direction, and an intermediate transfer member unit 7 is arranged on the left side of the photoreceptors 1Y, 1M, 1C and 1Bk in the figure. The intermediate transfer body unit 7 is a semiconductive endless belt-like intermediate transfer body 70 which is rotatably supported by a plurality of rollers 71, 72, 73, 74, and the inside of the intermediate transfer body 70. The first transfer rollers 5Y, 5M, 5C, 5Bk and the second transfer roller 5b, which are disposed in the first embodiment, and the cleaning means 6b.

  The process cartridges of the image forming units 10Y, 10M, 10C, and 10Bk and the intermediate transfer member unit 7 are accommodated in the housing 8, and the housing 8 is pulled out from the apparatus main body A via the support rails 82L and 82R. It is configured to be possible.

  In the image forming apparatus configured as described above, a toner image is formed by the image forming units 10Y, 10M, 10C, and 10Bk. Specifically, first, the surfaces of the photosensitive members 1Y, 1M, 1C, and 1Bk are uniformly negatively charged by the discharging means 2Y, 2M, 2C, and 2Bk. Next, the surfaces of the photosensitive members 1Y, 1M, 1C, and 1Bk are exposed based on the image signals by the exposure units 3Y, 3M, 3C, and 3Bk, and electrostatic latent images are formed. Further, toner charged to the same polarity as the electrostatic latent image is supplied to the surface of the photosensitive members 1Y, 1M, 1C, 1Bk by the developing means 4Y, 4M, 4C, 4Bk, so that the electrostatic latent image is developed. To form a toner image of each color. Then, after the surface of the photosensitive members 1Y, 1M, 1C, 1Bk is removed by the pre-transfer discharging means 9Y, 9M, 9C, 9Bk to reduce the potential difference between the image area and the non-image area, The transfer current is applied from the primary transfer rollers 5Y, 5M, 5C, and 5Bk to sequentially transfer and superimpose on the intermediate transfer member 70 which is moved cyclically, whereby a color toner image is formed. Thereafter, a transfer material (image support carrying a fixed final image: for example, plain paper, transparent sheet, etc.) P accommodated in the sheet feeding cassette 20 is fed by the sheet feeding means 21 and a plurality of intermediate rollers 22A , 22B, 22C, 22D, and the registration roller 23, the sheet is conveyed to the secondary transfer roller 5b. Then, the secondary transfer roller 5b is brought into contact with the intermediate transfer member 70, and the color toner image is collectively transferred onto the transfer material P. Thereafter, the transfer material P to which the color toner image has been transferred is separated at a portion where the curvature of the intermediate transfer member 70 is high, conveyed to the fixing means 24, fixed by the fixing means 24, and nipped by the paper discharge roller 25. The sheet is placed on the sheet discharge tray 26 outside the machine.

On the other hand, the photoreceptors 1Y, 1M, 1C, 1Bk after the toner images of the respective colors are transferred onto the intermediate transfer member 70 by the primary transfer rollers 5Y, 5M, 5C, 5Bk are surfaced by the cleaning means 6Y, 6M, 6C, 6Bk. The toner remaining on the is removed.
Further, after the color toner image is transferred onto the transfer material P by the secondary transfer roller 5b, the intermediate transfer member 70 obtained by curvature separation of the transfer material P is subjected to removal of residual toner by the cleaning means 6b.

During the image forming process, the primary transfer roller 5Bk is always in contact with the photosensitive member 1Bk, and the other primary transfer rollers 5Y, 5M and 5C are associated with the corresponding photosensitive members 1Y and 1M only when forming a color toner image. , 1C.
The secondary transfer roller 5b is in contact with the intermediate transfer member 70 only when the secondary transfer is performed.

  Although FIG. 1 shows the image forming apparatus of the present invention as a color laser printer, the image forming apparatus of the present invention may be configured as a monochrome laser printer or a copy.

According to the image forming apparatus provided with the photosensitive member having the protective layer including the charge transfer agent contained in the cross-linked cured resin as described above, generation of transfer memory And the occurrence of toner scattering at the time of transfer can be suppressed.
Incidentally, in the image forming apparatus using a photosensitive member having a protective layer containing a crosslinking type cured resin but to which no charge transfer agent is added, transfer memory occurs even if charge removal before transfer is performed.

〔toner〕
The toner used in the image forming apparatus of the present invention may be a pulverized toner or a polymerized toner, but the image forming apparatus of the present invention is manufactured by a polymerization method from the viewpoint of obtaining an image of high image quality. It is preferable to use the polymerized toner.
Further, as the toner, it is preferable to use one in which the binder resin is made of a crystalline resin. By using a binder resin containing a crystalline resin as the toner, it is possible to suppress the occurrence of fog in the obtained image. It is considered that this is because the variation in charging when the toner is frictionally charged in the developing units 4Y, 4M, 4C, 4Bk is reduced.

  The volume average particle diameter of the toner, that is, the 50% volume particle diameter (Dv 50) is desirably 2 to 8 μm, more preferably 3 to 7 μm. By setting this range, the resolution can be increased.

  The toner according to the present invention may be used alone as a one-component developer, or may be mixed with a carrier and used as a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a toner containing magnetic particles of about 0.1 to 0.5 μm or so in a toner to make a magnetic one-component developer can be mentioned, and both of them are used. be able to.

  When mixed with a carrier and used as a two-component developer, conventionally known magnetic particles of the carrier include metals such as iron, ferrite and magnetite, and alloys of those metals and metals such as aluminum and lead. Materials can be used, in particular ferrite particles are preferred. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.

  The volume average particle size of the carrier can be measured typically by a laser diffraction type particle size distribution measuring apparatus "HELOS" (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably one in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and, for example, an olefin resin, a styrene resin, a styrene acrylic resin, a silicone resin, an ester resin or a fluorine-containing polymer resin is used. The resin for forming the resin-dispersed carrier is not particularly limited, and any known resin can be used. For example, styrene acrylic resin, polyester resin, fluorine resin, phenol resin, etc. may be used. it can.

  The method for producing the above-mentioned toner is not particularly limited. For example, known methods such as a usual grinding method, a wet melt-spheronization method prepared in a dispersion medium, suspension polymerization, dispersion polymerization, emulsion polymerization aggregation method, etc. And the like.

  To the toner particles, inorganic particles such as silica and titania having an average particle diameter of about 10 to 300 nm and an abrasive having an average particle diameter of about 0.2 to 3 μm can be externally added as external additives.

The toner may be used as a magnetic or nonmagnetic one-component developer, but may be mixed with a carrier and used as a two-component developer.
When the toner is used as a two-component developer, conventionally known materials such as ferromagnetic metals such as iron, ferromagnetic metals and alloys such as aluminum and lead, compounds of ferromagnetic metals such as ferrite and magnetite, etc. And magnetic particles made of ferrite, and ferrite is particularly preferable.

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

  EXAMPLES Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the following examples.

Preparation Example 1 of Photoreceptor
(1) Preparation of conductive support The surface of a drum-like aluminum support (outer diameter 100 mm, length 360 mm) is cut and a conductive support [1] having a surface roughness Rz = 1.5 (μm) Was produced.

(2) Intermediate Layer Forming Step Dispersion was performed for 10 hours by a batch system using a sand mill with the following raw materials as a disperser, to prepare an intermediate layer forming coating solution [1].
-Binder resin: Polyamide resin "X1010" (made by Daicel-Evonik)
1 part by mass Solvent: ethanol 20 parts by mass Metal oxide particles: titanium oxide particles having a number average primary particle size of 0.035 μm “SMT500SAS” (manufactured by Tayca Corporation) 1.1 parts by mass The conductive support [1] Then, this intermediate layer forming coating solution [1] was applied by dip coating to form a coated film, and this coated film was dried at 110 ° C. for 20 minutes to form an intermediate layer [1] having a layer thickness of 2 μm. .

(3) Organic photosensitive layer formation process (charge generation layer formation process)
Dispersion was performed for 10 hours using a sand mill as a disperser for the following raw materials, to prepare a coating solution [1] for charge generation layer formation.
Charge-generating substance: titanyl phthalocyanine pigment (having a maximum diffraction peak at a position of at least 5 at 27.3 ° as measured by Cu-Kα characteristic X-ray diffraction spectrum) 20 parts by mass Binder resin: polyvinyl butyral resin “# 6000-C (Made by Denki Kagaku Kogyo Co., Ltd.)
10 parts by mass Solvent: t-butyl acetate 700 parts by mass Solvent: 4-methoxy-4-methyl-2-pentanone 300 parts by mass The coating liquid for forming the charge generation layer [1] on the intermediate layer [1]. ] Was applied by a dip coating method to form a coated film, thereby forming a charge generation layer [1] having a layer thickness of 0.3 μm.

(Charge transport layer formation process)
The following raw materials were mixed and dissolved to prepare a charge transport layer forming coating solution [1].
Charge transport agent: 150 parts by mass of the compound represented by the formula (A) Binder resin: polycarbonate resin “Z300” (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
300 parts by mass Solvent: toluene / tetrahydrofuran = 1/9 volume% 2000 parts by mass Antioxidant: “Irganox 1010” (manufactured by Nippon Ciba-Geigy Co., Ltd.) 6 parts by mass Leveling agent: silicone oil “KF-54” (Shin-Etsu Chemical Co., Ltd. 1 part by mass This charge transport layer forming coating solution [1] is applied onto the charge generation layer [1] by dip coating to form a coated film, and the coated film is dried at 120 ° C. for 70 minutes To form a charge transport layer [1] having a thickness of 20 μm.

(4) Protective layer formation step After dispersing the following polymerizable compound, solvent and metal oxide fine particles for 10 hours using a sand mill as a disperser under light shielding, add the following photo polymerization initiator and mix under light shielding, The mixture was stirred and dissolved to prepare a protective layer-forming coating solution [1].
Polymerizable compound: 100 parts by mass of trimethylolpropane trimethacrylate Charge transport agent: 24 parts by mass of a compound represented by the above formula (CTM-13) Inorganic fine particles: surface treatment agent (CH ₂ CC (CH ₃ ) COO 150 parts by mass of tin oxide fine particles having a number average primary particle diameter of 20 nm surface-treated with (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ), solvent: sec-butanol 315 parts by mass, solvent: tetrahydrofuran 15 parts by mass, photopolymerization start Agent: “IRGACURE 819” (manufactured by BASF Japan Ltd.) 12 parts by mass The coating solution [1] for forming a protective layer is coated on the charge transport layer [1] by using a circular slide hopper coating apparatus to form a coating film Formed. The coated film is dried at room temperature for 20 minutes, and then under a nitrogen flow of 13.5 L / min, a xenon lamp is used as a light source, and the distance between the light source and the surface of the coated film is 5 mm, lamp output wavelength 365nm light at 4 kW (intensity: 4000 mW / cm ^2, the irradiation intensity of the light in the coating film: 1800mW / cm ²⁾ by a 18 seconds irradiation, to form a protective layer having a thickness of 3.5μm (1), Thus, a photosensitive member [1] was produced.

Preparation Example 2 of Photoreceptor
In the formation of the protective layer in Preparation Example 1 of the photoreceptor, the same method is used except that the compound represented by the formula (A) is used instead of the compound represented by the formula (CTM-13) as the charge transport agent. To prepare a photosensitive member [2].

[Preparation Examples 3 and 4 of Photoreceptor]
In the step of forming the protective layer in Preparation Example 1 of the photosensitive member, the number average primary surface-treated with surface treatment agent (CH ₂ CC (CH ₃ ) COO (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ) as inorganic fine particles. Number average primary particle diameter of 20 nm surface-treated with a surface treatment agent (CH ₂ CC (CH ₃ ) COO (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ) instead of tin oxide fine particles having a particle diameter of 20 nm Aluminum oxide fine particles, copper aluminate fine particles having a number average primary particle diameter of 20 nm surface-treated with a surface treatment agent (CH ₂ CC (CH ₃ ) COO (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ) Photosensitive members [3] and [4] were produced in the same manner as the others.

Preparation Example 5 of Photoreceptor
A photosensitive member [5] was produced in the same manner as in the formation of the protective layer in Production Example 1 of the photosensitive member, except that the charge transfer agent was not added.

Example 1
As an evaluation machine, a pre-transfer charge removing means consisting of an LED light emitting device is installed downstream of the developing means and upstream of the transfer means on the peripheral surface of the photosensitive member of the full color image forming apparatus "Bizhub press C1070" (manufactured by Konica Minolta). The photoconductor [1] was mounted on the evaluation machine using the modified machine.
The charge removal by the pre-transfer charge removal means in this evaluation machine uses light of wavelength 780 nm as the exposure light, and the potential difference after charge removal represented by the potential of the image area (V1) -non-image area (V2) is 100 [-V]. I went to be.
After performing an endurance test of printing 250,000 sheets of a coverage chart of 5% of each color with A4 using the above-mentioned evaluation machine, the following transfer memory was evaluated.

<Evaluation of transfer memory>
After the endurance test, a green triangle chart is printed on A3-sized "POD gloss coated paper (100 g / m ² )" (manufactured by Oji Paper Co., Ltd.) under an environment of temperature 30 ° C. and humidity 80% RH, The difference in density between the image area corresponding to the first rotation of the image and the image area corresponding to the second rotation of the photosensitive member is visually observed, and the difference in density is not observed at all in both image areas. The evaluation was divided into 10 levels and evaluated until the rank "J" where the density difference in the image area was extremely remarkably observed. The results are shown in Table 1.
In the present invention, the cases of ranks "A" to "F" are taken as pass, and the cases of ranks "G" to "J" are taken as fail.

Example 2
A durability test is conducted in the same manner as in Example 1 except that the charge removal before transfer is performed so that the potential difference after charge removal is 50 [-V], and then the transfer is performed in the same manner as in Example 1. We evaluated the memory. The results are shown in Table 1.

[Example 3]
A durability test is conducted in the same manner as in Example 1 except that the charge removal before transfer is performed so that the potential difference after charge removal becomes 0 [-V], and then transfer is performed in the same manner as in Example 1. We evaluated the memory. The results are shown in Table 1.

[Examples 4 to 6]
A durability test was conducted in the same manner as in Example 3 except that photoreceptors [2] to [4] were used instead of photoreceptor [1], and then transfer memory in the same manner as in Example 1. We made an evaluation of. The results are shown in Table 1.

Comparative Example 1
In Example 1, a durability test was carried out in the same manner as in Example 1 except that the evaluation machine was not provided with the pre-transfer charge-removing means, and the photoreceptor [5] was used instead of the photoreceptor [1]. The evaluation on the transfer memory was performed in the same manner as in. The results are shown in Table 1.

Comparative Example 2
A durability test was carried out in the same manner as in Example 1 except that the pre-transfer charge-removing means was not provided in the evaluation machine, and thereafter evaluation on the transfer memory was carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3
The durability test was conducted in the same manner as in Example 3 except that the photosensitive body [5] was used instead of the photosensitive body [1], and then the transfer memory was evaluated in the same manner as in Example 1. The The results are shown in Table 1.

As is apparent from Table 1, in Examples 1 to 6 according to the present invention in which the photosensitive members [1] to [4] according to the present invention were used and pre-transfer charge removal was performed, the generation of transfer memory was suppressed. It is confirmed that you can do it.
Further, in the first to sixth embodiments according to the present invention, the difference between the potential Va of the portion (non-image portion) to which the toner is not attached and the surface potential Vb of the toner over the portion (image portion) to which the toner is attached Since the charge removal was performed so that (the potential difference after charge removal) was 0 [-V] or more, the toner scattering was not observed in the image of the green triangular chart related to the evaluation of the transfer memory.

1Y, 1M, 1C, 1Bk Photosensitive members 2Y, 2M, 2C, 2Bk Charging unit 3Y, 3M, 3C, 3Bk Exposure unit 4Y, 4M, 4C, 4Bk Developing unit 5Y, 5M, 5C, 5Bk Primary transfer roller 5b Secondary transfer Rollers 6Y, 6M, 6C, 6Bk, 6b Cleaning means 7 Intermediate transfer member unit 8 Housings 9Y, 9M, 9C, 9Bk Pre-transfer static elimination means 10Y, 10M, 10C, 10Bk Image forming unit 20 Paper feed cassette 21 Paper feed means 22A , 22B, 22C, 22D Intermediate roller 23 Registration roller 24 Fixing means 25 Ejection roller 26 Ejection tray 70 Intermediate transfer members 71, 72, 73, 74 Rollers 82L, 82R Support rail A Main body SC Original image reader P Transfer material

Claims (3)

Charging means for charging the surface of the photosensitive member along the rotational direction of the photosensitive member in the outer peripheral surface region of the rotating photosensitive member, exposure means for exposing the photosensitive member charged by the charging means, and the exposure means Developing means for supplying toner to the photosensitive member exposed by the above to form a toner image, pre-transfer charge-eliminating means for discharging the surface of the photosensitive member by exposing it, and transferring the toner image on the photosensitive member onto a transfer material Transfer means are sequentially arranged,
The pre-transfer charge removing unit is configured such that a potential Va of a portion (non-image portion) to which no toner is attached in the toner image formed by the developing portion and a surface of the portion (image portion) over the toner The charge is removed under the condition that the potential Vb is VaVaVb,
An image forming apparatus, wherein the outermost surface layer of the photosensitive member comprises a protective layer in which a charge transfer agent is contained in a cured resin obtained by polymerizing a crosslinkable polymerizable compound. The image forming apparatus according to claim 1, wherein the charge transport agent is a compound represented by the following general formula (1).

[In the general formula ^{(1), R 1, R} 2, R 3 and R ⁴ each independently represents an alkyl group or an alkoxy group having 1 to 7 carbon atoms having 1 to 7 carbon atoms. k, l and n each represent an integer of 0 to 5, and m represents an integer of 0 to 4. However, when k, l, n or m is 2 or more, plural R ¹ , R ² , R ³ or R ⁴ may be the same as or different from each other . ]   The image forming apparatus according to claim 1, wherein the protective layer further contains inorganic fine particles.

Images