JP4869726B2 - Image forming method - Google Patents

Description

The present invention relates to an image forming method applied to an electrophotographic apparatus such as a copying machine, a facsimile machine, and a laser printer. More specifically, the present invention relates to an image forming method in which a toner image is transferred using a belt such as a transfer belt or an intermediate transfer belt.
The present invention also relates to an image forming apparatus and a transfer apparatus using the image forming method.

In electrophotography, the surface of a photoconductor is uniformly charged to a predetermined polarity, and then image exposure is performed by light irradiation based on predetermined document information to form an electrostatic charge image. An image is formed, the toner image is transferred to a transfer material such as paper, and the toner image is fixed to the transfer material by heating and pressing with a fixing roller, thereby forming an image. Further, after the toner image is transferred, the surface of the photosensitive member is cleaned by a cleaning blade or the like to remove the remaining toner, and if necessary, the charge is removed by light irradiation or the like, and the next image forming process is performed.
In such an image forming process, contact transfer, more specifically bias roller transfer, is being studied in place of conventional corona transfer in order to reduce the amount of ozone generated in the toner image transfer process.
In order to realize bias roller transfer, a method has been proposed in which a roller resistance value is detected by applying a constant current and a transfer bias is set based on the value as shown in Patent Document 1 and the like. ing. Non-Patent Document 1 states that the resistance value of the transfer roller in the bias roller transfer system needs to be at least 5.16 × 10 ⁸ Ω or more and a transfer voltage of at least 1200 V or more. If the transfer voltage is high, a high voltage power supply of several kV is required, which is disadvantageous in terms of cost and safety.
Further, as disclosed in Patent Document 2 and the like, a technique for improving toner scattering and transferability by using offset transfer for offsetting the arrangement position of each transfer unit is known.
However, the above method is problematic because it is difficult to maintain transferability under a low transfer voltage and a surface resistivity of the transfer body.

JP-A-2-123385 Japan HardCopy 91 Fall p29 JP 05-265332 A

  Accordingly, the present invention has been made in view of the above-described problems, and the problem thereof is an image forming method and an image forming apparatus capable of improving / maintaining transferability even under a low transfer voltage and a surface resistivity of a transfer body. And providing a transfer device.

The features of the present invention, which is a means for solving the above problems, are listed below.
The present invention provides an image forming method having a process in which toner is brought into contact with a transfer medium, wherein a transfer voltage in the transfer process is in a range of 400 to 900 V, and a surface resistivity of the transfer object is 1 × 10. ⁹ to 1 × 10 ¹¹ Ω / □, and the toner is a toner in which an external additive is externally added to the resin base particles, and at least one of the external additives is represented by the following general formula (Formula 2)
[M1] _a Si _b O _c
(In the above formula, M1 represents a metal element selected from Sr, Mg, Zn, Co, Mn and Ce, a and b represent an integer of 1 to 9, and c represents an integer of 3 to 9)
The composite oxide has a relative dielectric constant of 2 to 10 and a volume resistivity of 10 ¹¹ Ω · cm or more measured at 1 MHz, and the bias application unit and the bias are used as the transfer method. The image forming method is characterized in that a path for offsetting the positions of the latent image carrier to which toner is applied and the transfer roller is provided between the injection portion and the injection portion.
The present invention includes a step of contacting and transferring the toner to the transfer medium via a transfer medium between a latent image carrier to which toner is applied and a transfer roller, and primary transfer in the transfer process The voltage is in the range of 400 to 900V.
The present invention is characterized in that the transfer roller is made of metal.
The present invention is characterized in that the transfer body is an intermediate transfer body, and has a step of secondary transfer from the intermediate transfer body to a fixing medium.
The present invention is characterized in that M1 of the composite oxide is Mg.
The present invention is characterized in that the complex oxide is any of forsterite, steatite, and enstatite.
The present invention is characterized in that the content of the composite oxide is 0.1 to 5.0 mass% with respect to the toner base.
The present invention is characterized in that the toner is a non-magnetic one-component developing toner.
The present invention is characterized in that the toner is a non-magnetic two-component developing toner.
The invention features a volume resistivity of the transfer object is ^{1 × 10 9 ~1 × 10 11} Ω · cm.

  According to the present invention, it is possible to provide an image forming method, an image forming apparatus, and a transfer apparatus capable of improving / maintaining transferability even under a low transfer voltage and a surface resistivity of a transfer body by the means for solving the problems. It became.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims. In addition, “part” in the text represents “part by mass”.

The toner particles constituting the toner for forming a full color image of the present invention have at least a colorant and a resin, and are treated with inorganic fine particles. At least one kind has a relative dielectric constant of 2 to 10 and a volume measured at 1 MHz. The toner is characterized by being treated with inorganic fine particles of a complex oxide having a specific resistance of 10 ¹¹ Ω · cm or more.
The composite oxide has a dielectric constant measured at 1 MHz of 2 to 10, more preferably 3 to 9, and a volume resistivity of 10 ¹¹ Ω · cm or more, preferably 10 for the purpose of assisting the charging property of the toner particles. Those having ¹² Ω · cm or more are preferable.
If the dielectric constant is less than 2, it does not function as a charging aid, and if it is more than 10, it causes a charge-up, and the toner is not uniformly charged in the developing device. On the other hand, if the volume specific resistance is smaller than 10 ¹¹ Ω · cm, the surface resistance is lowered when the electrostatic latent image holding member is attached to the charging member for charging the electrostatic latent image holding member, and charging of the electrostatic latent image holding member is caused.
The following composite oxides are preferably used as external additives.

(Chemical formula 3)
[M1] _a Si _b O _c
(In the above formula, M1 represents a metal element selected from Sr, Mg, Zn, Co, Mn and Ce, a and b represent an integer of 1 to 9, and c represents an integer of 3 to 9).
In particular, forsterite (Mg ₂ SiO ₄ ) and steatite (MgSiO ₃ ) are preferable because the effects of the present invention can be further exhibited.

The primary particle diameter of the composite oxide is suitably 0.05 to 1 μm, preferably 0.08 to 1 μm. If it is smaller than 0.05 μm, it is buried by stress at the thin layer forming portion of the developing device, and the effect at the end of durability cannot be exhibited. On the other hand, if it is larger than 1 μm, it is detached from the toner surface, and the effect at the end of the durability cannot be exhibited.
The amount of the composite oxide added is suitably 0.1 to 1.5 parts by weight, preferably 0.2 to 1.5 parts by weight, based on 100 parts by weight of the toner base. If the amount is less than 0.1 parts by mass, the effect of assisting charging cannot be exhibited, causing charge-up, and toner charging in the developing device becomes non-uniform. When the amount is more than 1.5 parts by mass, reversely charged toner is likely to be generated when used as a negatively charged toner, and background staining is likely to occur. This is because magnesium silicate tends to be positively charged due to the influence of the MgO portion, which tends to be strongly positively charged, as shown by the relationship of electronegativity.

Forsterite and steatite have a very weak adhesion to metal for unknown reasons. For this reason, when the thin layer forming member in the developing device is a metal, the adhesion of the toner to the metal is suppressed. When a metal roller is used, the prevention of filming and the improvement of the toner reset property are promoted, and a metal blade is used. In the case, there is an effect of preventing filming.
Furthermore, although the reason is not clear, the composite oxide has a low dielectric constant and low dielectric loss, so that the charge is uniform, the charge rises immediately, and the charge is easily held because of the high resistance. For this reason, it is considered that the transfer easily improves from the photosensitive member to the transfer target due to the bias. Further, since the chargeability of the composite oxide is on the positive charge side as compared with the toner base, it is considered that the electrostatic adhesion with the photoreceptor is reduced and the transferability is improved.

  The toner base that can be used in the present invention usually contains a binder resin, a colorant, and other additives. In this toner base, (1) a colorant, a charge control agent, a release agent and the like are melt-mixed in a thermoplastic resin as a binder resin component and uniformly dispersed to obtain a composition. A toner base obtained by pulverizing and classifying the product, and (2) a polymerization initiator in which a colorant, a charge control agent, a release agent and the like are dissolved or suspended in a polymerizable monomer which is a binder resin raw material. A toner base obtained by dispersing in an aqueous dispersion medium containing a dispersion stabilizer, heating to a predetermined temperature to start suspension polymerization, and filtering, washing, dehydrating and drying after completion of the polymerization, (3) The primary particles of the binder resin containing a polar group obtained by emulsion polymerization are aggregated by adding a colorant and a charge control agent to form secondary particles, and the temperature is higher than the glass transition temperature of the binder resin. Filter and dry the particles that have been agitated and associated with (4) Using a hydrophilic group-containing resin as a binder resin, adding a colorant or the like to the resin and dissolving it in an organic solvent, then neutralizing the resin to perform phase inversion, and then drying. Examples thereof include a phase inversion emulsification method toner base material for obtaining colored particles, and any of them can be used.

(Toner component)
(Binder resin)
Known binder resins can be used. For example, polyester, polyurethane, polyol, polyurea, epoxy resin, vinyl resin, and hybrid resins thereof.

(Coloring agent)
A well-known thing can be used as a coloring agent. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa Yellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL , Isoindolinone yellow, bengara, red lead, red lead, cadmium red, cadmium mercury red, antimony red, permanent red 4R, para red, phise red, parachlor ortho nitroaniline red, risor fast scarlet G, Reliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pogment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, oil red, quinacridone red, pyrazolone red, polyazo red, chrome vermilion, benzidine Range, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo , Ultramarine, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt violet, manganese violet, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridiane, emerald green, pigment green B, naphthol green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, Oxidized Chi Tan, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by mass, preferably 3 to 10% by mass with respect to the toner.

(Colorant masterbatch)
The colorant used in the present invention can also be used as a master batch combined with a resin. As the resin to be kneaded together with the production of the masterbatch or the masterbatch, in addition to the above-mentioned binder resins, styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene, and its substituted polymers; styrene-p- Chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acrylic Acid butyl copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate Copolymer, styrene-acrylonitrile copolymer Styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer Styrenic copolymers such as: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin , Modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like, which can be used alone or in combination.

(wax)
The toner base of the present invention may contain a wax for the purpose of improving the releasability between the fixing member and the recording member in the fixing process.
For example, polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbon (paraffin wax, sazol wax, etc.); carbonyl group-containing wax, etc. may be mentioned. Carbonyl group-containing waxes include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18. -Octadecandiol diol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylenediamine dibehenyl amide, etc.); And dialkyl ketones (such as distearyl ketone).
In the present invention, it is more preferable that the wax content in the toner is 3 to 15% by mass, preferably 4 to 12% by mass with respect to 100% by mass of the resin component. If the amount of wax relative to the total amount of toner is less than 3%, at the time of fixing, the wax exudes on the surface of the fixing member so as not to stick to the fixing member. For this reason, the margin for hot offset may be lost. On the other hand, if it exceeds 15%, the wax melts at a low temperature and is easily affected by thermal energy and mechanical energy. When the carrier is agitated with the carrier in the developing portion, the wax is detached from the toner surface, and the toner regulating member or photosensitive member is exposed. May adhere to the body and cause image noise.
Moreover, the endothermic peak at the time of temperature rise measured by the differential scanning calorimeter (DSC) of wax becomes like this. Preferably it is 65-115 degreeC, More preferably, it is 70-90 degreeC. When the melting point is less than 65 ° C., the fluidity is deteriorated or blocking occurs during storage. On the other hand, when the temperature is higher than 115 ° C., the releasability at the time of fixing tends to deteriorate.

(Manufacturing method of toner base)
A known method can be applied as a method for producing the toner base. Examples thereof include a pulverization method, a known wet granulation method, such as a suspension polymerization method, an emulsion polymerization association method, and a dissolution suspension method.

(About particle diameter and shape of toner base)
The volume average particle size of the toner base is preferably 3 to 12 μm, particularly 4 to 9 μm. If the particle size is 3 μm or less, the toner has a too small particle size, and it is impossible to achieve a narrow particle size distribution as the toner. As a result, a delicate image cannot be formed. On the other hand, when the thickness is 12 μm or more, the reproducibility of high-definition printing deteriorates.

(Types of fine particles)
In the present invention, known inorganic fine particles or organic fine particles other than magnesium silicate may be used for the purpose of assisting the fluidity, developability and chargeability of the toner. As the inorganic fine particles, the primary particle diameter is preferably 2 nm to 2 μm, and particularly preferably 5 nm to 500 nm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5% by mass of the toner, and particularly preferably 0.01 to 2.0% by mass. Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

(Mixing with fine particles)
Magnesium silicate and other fine particles are adhered to the toner surface by being mixed with a toner base by a Henschel mixer, a super mixer, an Auster blender or the like. Adhesion of magnesium silicate and other fine particles to the toner can be adjusted as appropriate depending on the mixing time, the rotational speed of the mixing blade of the mixer, and the like.

(Two-component developer)
When a toner is used as a two-component developer, the magnetic carrier mixed with the toner is not particularly limited, and known ones such as ferrite and iron powder are used and are resin-coated. Also good. Such a carrier generally preferably has an average particle size (volume center particle size) of 40 to 100 μm. The toner and the magnetic carrier are preferably mixed in a weight ratio of 2:98 to 10:90, particularly 3:97 to 8:92.

Next, the transfer device will be described.
An example of a transfer device is shown in FIG. An image forming unit having four photoconductors 101 to 104 is disposed, and the intermediate transfer belt 100 is stretched by the belt driving roller 111, the stretching roller 112, and the secondary transfer opposing roller 109, and the running direction of the intermediate transfer belt. By applying a predetermined voltage to the primary transfer rollers 105 to 108 from the upstream side, a color image is formed by superimposing each color on the intermediate transfer belt 100. The formed color image is transferred to a sheet 114 as a transfer material by applying a predetermined voltage to the secondary transfer roller 110, and is fixed (not shown) and output. The toner that cannot be transferred by the secondary transfer roller 110 and remains on the intermediate transfer belt is collected by the cleaner unit 113. When forming a monochrome image, image formation is performed in the same manner as color image formation as shown in FIG. 1, or as another example, as shown in FIG. 2, the black primary transfer roller 205 and the stretching roller 215 are formed. ˜216, the black color primary transfer rollers 206 to 208 and the cleaner unit 213 are retracted while the black photosensitive member 201 is in contact with the black primary transfer roller 205 to form a monochrome image.
An example of the offset transfer device is shown in FIG. The transfer rollers 305 to 308 are offset by 5 to 10 mm on the downstream side of the photoconductors 301 to 304 correspondingly abutting with the running direction of the intermediate transfer belt 300, so that the transfer rollers 305 to 308 and the photoconductors 301 to 301 are used during color image formation. The amount of biting with 304 was 0.5 mm. By offsetting and biting the primary transfer rollers 305 to 308, the primary transfer rollers 305 to 308 do not directly apply a load to the photosensitive members 301 to 304 via the intermediate transfer belt 300, and the intermediate transfer belt 300 Since a transfer nip can be formed on the photoconductors 301 to 304, the hardness of the primary transfer rollers 305 to 308 can be set without being involved in transfer defects. The offset amount and the amount of biting can be arbitrarily set so that the gap between the photosensitive member and the primary transfer roller is larger than the thickness of the intermediate transfer belt.

FIG. 4 shows an example of the image forming apparatus. Of the constituent elements such as the photoreceptor 1, the charging unit 2, the developing unit 4, and the cleaning unit 6, the developing unit 4 using the toner of the present invention and other unit or units are integrally coupled as a process cartridge. The process cartridge is configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.
In an image forming apparatus equipped with a process cartridge having a developing means 4 using toner of the present invention, the photoreceptor 1 is rotationally driven at a predetermined peripheral speed. In the rotating process, the photosensitive member 1 is subjected to a uniform withstand voltage of positive or negative predetermined potential on the peripheral surface by the charging unit 2, and then receives image exposure light from the image exposure unit 3 such as slit exposure or laser beam scanning exposure. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoreceptor 1, and the formed electrostatic latent images are then developed with toner by the developing means 4, and the developed toner image is transferred from the paper feeding unit to the photoreceptor 1. Then, the transfer unit 5 sequentially transfers the toner to the transfer material 9 fed in synchronization with the rotation of the photosensitive member 1. The transfer material 9 that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means 8, and fixed on the image, and printed out as a copy (copy). The surface of the photoreceptor after the image transfer is cleaned by removing the transfer residual toner by the cleaning means 6, and after being further neutralized, it is repeatedly used for image formation.

  The present invention is an image forming method in which transfer is performed at a transfer voltage of 400 to 900 V using the external additive. As a result, a transfer voltage of 1200 V or more has been conventionally required, but the transfer voltage can be lowered, and the cost and safety can be improved. In addition, this is an image forming method in which high transfer efficiency can be obtained even when the transfer voltage is low, and good image formation can be performed.

Next, examples will be described.
Example 1
Preparation of Toner 1 Polyester resin A (softening point 131 ° C., AV value 25) ... 68 parts Polyester resin B (softening point 116 ° C., AV value 1.9) ... 32 parts Cyan Masterbatch (Pigment Blue 15: 3) ) 8 parts Carnauba wax ...... 4 parts After thoroughly mixing the above toner material with a Henschel mixer, remove the discharge part of the twin-screw extrusion kneader (PCM-30: manufactured by Ikekai Tekko Co., Ltd.) The resulting mixture was melt-kneaded, rolled to a thickness of 2 mm with a cooling press roller, cooled with a cooling belt, and then coarsely pulverized with a feather mill. Then, after pulverizing with a mechanical pulverizer (KTM: Kawasaki Heavy Industries, Ltd.) to an average particle size of 10-12 μm, and further pulverizing with a jet pulverizer (IDS: Nippon Pneumatic Industrial Co., Ltd.), Fine powder classification was performed using a rotor type classifier (Teplex type classifier type 100ATP: manufactured by Hosokawa Micron Corporation) to obtain a toner base A having a volume average particle diameter of 7.9 μm.
1.0 part of forsterite 1 (average secondary particle size 0.39 μm, average primary particle size 80 nm) and 1 part of silica (RX200) are added to 100 parts of this toner base A, and the peripheral speed is 40 m with a Henschel mixer. / Sec for 5 minutes to obtain toner 1.
For other toners 2 to 9 in Examples 2 to 5 and Comparative Examples 1 to 4, toners were similarly prepared as shown in Table 1.

(Specific permittivity measurement)
1 g of the measurement object was placed in a liquid cell (12964A type 5 mL liquid measurement cell), which was sandwiched between electrodes, and measured with an impedance analyzer 1260 type (manufactured by Solartron) at AC 1 MHz.
(Volume resistivity measurement)
3 g of toner was sandwiched between electrodes of a sample box TR42 for measuring ultrahigh resistance manufactured by Advantest, and measured at DC 500 V using a digital ultrahigh resistance / microammeter R8340A.
(Transferability evaluation (primary transfer efficiency))
A BK solid image is printed using a machine with a modified intermediate transfer belt / transfer roller using Ricoh's Ipsio CX400, and the amount of adhesion on the photoconductor and the intermediate transfer belt is measured by using an external power supply and varying the transfer bias. The primary transfer efficiency was measured, and the primary transfer efficiency of 95% or more was determined to be an OK level.

  From Table 1, in the Examples, good transferability of 97% or more transfer efficiency was obtained even under a low transfer voltage and a surface resistivity of the transfer body. On the other hand, in the comparative example, the transfer efficiency was as bad as 95% or less.

  In the present invention, by using the above complex oxide as an external additive in the toner, transferability can be improved / maintained even under a low transfer voltage and a surface resistivity of the transfer body, and a high voltage power supply of several kV Therefore, it is possible to provide a highly reliable contact transfer apparatus that is advantageous in reducing the size of the apparatus and reducing the manufacturing cost.

It is the figure which showed the example of the transfer apparatus. It is the figure which showed the example of the transfer apparatus. It is the figure which showed the example of the offset transfer apparatus. 1 is a diagram illustrating an example of an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging means 3 Exposure means 4 Developing means 41 Developing sleeve 45 Toner hopper 5 Transfer means 51 Transfer member 52 Static elimination mechanism 6 Cleaning means 61 Cleaning member 62 Toner recovery chamber 7 Static elimination means 8 Fixing means 9 Transfer material 100 Intermediate transfer belt DESCRIPTION OF SYMBOLS 101 Photoconductor 102 Photoconductor 103 Photoconductor 104 Photoconductor 105 Primary transfer roller 106 Primary transfer roller 107 Primary transfer roller 108 Primary transfer roller 109 Secondary transfer counter roller 110 Secondary transfer roller 111 Belt drive roller 112 Stretching Roller 113 Cleaner unit 114 Paper 201 Black photosensitive member 205 Black primary transfer roller 206 Primary transfer roller for color 207 Primary transfer roller for color 208 Primary transfer roller for color 213 Cleaner unit 215 Tension roller 216 Tension roller 300 Intermediate transfer Belt 301 photoreceptor 302 a photoreceptor 303 a photoreceptor 304 a photoreceptor 305 transfer roller 306 transferring roller 307 transfer roller 308 transferring roller

Claims (10)

In a transfer type image forming method having a transfer step of transferring toner in contact with a transfer target,
In the image forming method, a transfer voltage in the transfer step is in a range of 400 to 900 V,
The surface resistivity of the transferred body is 1 × 10 ⁹ to 1 × 10 ¹¹ Ω / □,
The toner comprises a toner in which an external additive is externally added to the resin base particles.
At least one of the external additives is represented by the following general formula (Formula 1)
[M1] _a Si _b O _c
(In the above formula, M1 represents a metal element selected from Sr, Mg, Zn, Co, Mn and Ce, a and b represent an integer of 1 to 9, and c represents an integer of 3 to 9)
A composite oxide represented by
The complex oxide has a relative dielectric constant measured at 1 MHz of 2 to 10 and a volume resistivity of 10 ¹¹ Ω · cm or more,
An image forming method comprising: a path for offsetting a position of a latent image carrier to which toner is applied and a transfer roller between a bias applying unit and a bias injection unit as the transfer method. The image forming method according to claim 1,
The image forming method includes a step of contacting and transferring the toner to the transfer target member via a transfer target member between a latent image carrier to which toner is applied and a transfer roller,
The image forming method, wherein a primary transfer voltage in the transfer step is in a range of 400 to 900V. The image forming method according to claim 2.
In the image forming method, the transfer roller is made of metal. The image forming method according to claim 2 or 3,
The image forming method includes a step in which the transfer target is an intermediate transfer member and is secondarily transferred from the intermediate transfer member to a fixing medium. The image forming method according to any one of claims 1 to 4,
In the image forming method, M1 of the composite oxide is Mg. The image forming method according to any one of claims 1 to 5,
In the image forming method, the composite oxide is any one of forsterite, steatite, and enstatite. The image forming method according to any one of claims 1 to 6,
In the image forming method, the content of the composite oxide is 0.1 to 5.0% by mass with respect to the toner base. The image forming method according to any one of claims 1 to 7,
In the image forming method, the toner is a non-magnetic one-component developing toner. The image forming method according to any one of claims 1 to 8,
In the image forming method, the toner is a non-magnetic two-component developing toner. The image forming method according to any one of claims 1 to 9,
The image forming method is characterized in that the volume resistivity of the transferred material is 1 × 10 ⁹ to 1 × 10 ¹¹ Ω · cm.

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