JP2014109586A - Intermediate transfer body and image forming apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate transfer body that can reduce an adhesive force with toner, has an excellent cleaning property even in durable use, provides transfer efficiency as high as in the initial stage, and suppresses the occurrence of cracks and peeling-off on the surface even after repeated image output.SOLUTION: An intermediate transfer body includes a base material layer having a conductive agent dispersed therein, and a surface layer. The surface layer contains a silicon oxide film containing carbon; and the silicon oxide film has the deflection vibration peak of Si-CHin an infrared absorption spectrum, the content of carbon atoms of 40 atom% or more and 72 atom% or less, and the abundance ratio of O/Ci of 0.98 or more and 1.2 or less.

Description

  The present invention relates to an intermediate transfer member and an image forming apparatus using the same.

Conventionally, an electrostatic latent image formed on a photoconductor as a first image carrier is developed to form a toner image, and this toner image is primarily transferred to an intermediate transfer member as a second image carrier. A so-called intermediate transfer type image forming apparatus configured to perform secondary transfer onto a recording material such as paper later is known.
As a material constituting the intermediate transfer member, a resin material is generally used. Specific examples thereof include polyimide resin, polyamideimide resin, polycarbonate resin, polyvinylidene fluoride resin, polyether ether ketone resin, and the like.
With respect to such an intermediate transfer member, Patent Document 1 discloses an invention aimed at providing an intermediate transfer member having higher transferability and higher surface cleaning and durability. And the objective does not contain a carbon atom as a 1st inorganic compound layer and surface layer which contain a carbon atom on a base material, or contains a quantity of carbon atoms smaller than a 1st inorganic compound layer. It describes what can be achieved with an intermediate transfer member having an inorganic compound layer. Furthermore, as the first inorganic compound layer, it is preferable that the carbon content is 0.1 atomic% to 50 atomic% or less because an intermediate transfer body having more excellent durability can be obtained. Regarding the inorganic compound layer 2, it is disclosed that the carbon content is preferably 20 atom% or less because an intermediate transfer body with more excellent releasability can be obtained.

International Publication No. 2007/046260

“Journal of the Adhesion Society of Japan”, Adhesion Society of Japan, 1972, Vol. 8, No. 3, p. 131-141

However, according to the study by the present inventors, the intermediate transfer member according to Patent Document 1 still has room for improvement in the transfer property of the toner carried on the surface to the paper, that is, the secondary transfer property.
SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic intermediate transfer member excellent in secondary transfer efficiency. Another object of the present invention is to provide an image forming apparatus capable of outputting a high-quality electrophotographic image.

According to the present invention, an intermediate transfer body having a base material layer in which a conductive agent is dispersed and a surface layer, the surface layer containing a silicon oxide film containing carbon, the silicon oxide film, Sum of the number of carbon atoms, silicon atoms and oxygen atoms in the silicon oxide film of carbon atoms having a Si—CH ₃ bending vibration peak in the infrared absorption spectrum and forming bonds with silicon atoms. And the ratio of the number of oxygen atoms forming a bond with the silicon atom to the number of silicon atoms is 0.85 or more and 1.2 or less. An intermediate transfer member is provided.
In addition, according to the present invention, an image forming apparatus provided with the above intermediate transfer member is provided.

  According to the present invention, an intermediate transfer member for electrophotography having high secondary transfer efficiency can be obtained. Further, according to the present invention, an image forming apparatus capable of obtaining a high-quality electrophotographic image can be obtained.

2 is a schematic cross-sectional view of an intermediate transfer member according to the present invention. FIG. 1 is a cross-sectional configuration diagram illustrating an image forming apparatus according to Embodiment 1. FIG. FIG. 6 is a cross-sectional configuration diagram illustrating an image forming apparatus according to a second embodiment and a third embodiment. It is explanatory drawing of the inductively coupled vacuum plasma CVD apparatus used in order to manufacture the surface layer of the intermediate transfer body which concerns on this invention.

<Intermediate transfer member>
A specific layer structure of the intermediate transfer member is shown in FIG.
As shown in FIG. 1A, the intermediate transfer member 8 has a base material layer 8b in which a conductive agent is dispersed and a surface layer 8a provided on the surface thereof. Further, as shown in FIG. 1B, an intermediate layer 8c may be provided between the base material layer 8b in which the conductive agent is dispersed and the surface layer 8a for the purpose of improving adhesion and smoothness. .

<Base material layer>
The base material layer of the intermediate transfer member has a shape such as a seamless belt shape, a cylindrical drum shape, or a roller shape, and uses a material in which a conductive agent is dispersed, a thermoplastic elastomer, a vulcanized rubber, or the like.
The resin that can be used for the base layer of the intermediate transfer member of the present invention is not particularly limited, but for example, olefin resins such as polyethylene and polypropylene, cyclic olefin copolymer resins, polystyrene resins, acrylic resins, polyethylene terephthalate, polyethylene Aromatic polyester resins such as butylene terephthalate, polycarbonate and polyarylate, alicyclic polyester resins such as cyclohexylene dimethylene terephthalate, sulfur-containing resins such as polysulfone, polyethersulfone and polyphenylene sulfide, polyvinylidene fluoride and polyethylene-tetrafluoroethylene. Fluorine-containing resin such as fluorinated ethylene copolymer, polyetheretherketone resin, thermoplastic polyimide resin, polyamide resin, polyamideimide resin, modified polyphenylene oxide resin Rukoto can. These thermoplastic resins may be used alone or in combination with a plurality of resins. Moreover, thermosetting resins, such as a polyimide resin, a polyester resin, a polyurethane resin, and an epoxy resin, can also be used.

Examples of the thermoplastic elastomer that can be used for the base material layer include polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and the like.
As vulcanized rubber that can be used for the base material layer, acrylonitrile / butadiene rubber, epichlorohydrin rubber, chloroprene rubber, acrylic rubber, butadiene rubber, styrene / butadiene rubber, isoprene rubber, urethane rubber, silicone rubber, ethylene / propylene rubber, etc. are used. be able to.

As a conductive agent that can be used for the base material layer, a known conductive agent can be used. For example, carbon black, carbon graphite, carbon nanofiber, carbon nanotube, conductive tin oxide, conductive titanium oxide, conductive zinc oxide, conductive powder such as conductive barium sulfate, conductive potassium titanate whisker, conductive titanic acid Conductive whiskers such as barium whiskers, carbon whiskers, quaternary ammonium salts, alkali metal salts of polyalkylene glycols, alkali metal salts of polyether amides, alkali metal salts of alkyl sulfates, glycerin monofatty acid esters, etc. Can be used. Among them, it is preferable to use carbon black because electric characteristics can be controlled over a wide range with a small addition amount.
The resistance of the base material layer of the intermediate transfer member is adjusted to a volume resistivity of 1 × 10 ² Ωcm or more and 1 × 10 ¹¹ Ωcm or less by means such as the amount of the conductive agent added or dispersion conditions.

<Surface layer>
The surface layer of the intermediate transfer member according to the present invention includes a silicon oxide film containing carbon, and the silicon oxide film has Si—C and Si—O chemical bonds derived from Si—CH ₃ bonds. Yes. The silicon oxide film has a carbon atom content of 40 atom% or more and 72 atom% or less in the analysis by XPS measurement.

In addition, the silicon oxide film has an abundance ratio (O / Si) of oxygen atoms bonded to silicon atoms to silicon atoms of 0.85 or more and 1.2 or less in analysis by XPS measurement.
In order to improve the secondary transfer efficiency of the intermediate transfer member, the present inventors have surface free energy of the surface layer that affects the adhesion of the toner to the surface layer, and the toner is carried on the surface of the intermediate transfer member. It was considered effective to adjust the half-life of the charging potential of the surface layer, which would affect the charge amount of the toner.

Here, the surface layer made of SiO ₂ has a very short half-life of the charging potential. In other words, when toner is carried on an intermediate transfer member having such a surface layer, the frictional charge of the toner disappears rapidly, and a bias is applied between the intermediate transfer member and paper during secondary transfer. Even when the toner is transferred, the toner is not smoothly transferred from the intermediate transfer member to the paper, and the secondary transfer efficiency is lowered. Here, as the reason why the half-life of the charging potential of the intermediate transfer member having a surface layer made of SiO ₂ is short, the inventors of the present invention are because the surface of the SiO ₂ film is hydrophilic and water easily adheres to the surface. I guessed that.

  Based on this assumption, the present inventors have studied to optimize the half-life of the charged potential of the silicon oxide film in order to suppress the rapid disappearance of the charge of the toner on the intermediate transfer member. As a result, it has been found that the half-life of the charged potential of the silicon oxide film can be extended by bonding a methyl group to the silicon atoms constituting the silicon oxide film. This is presumably because the surface of the silicon oxide film is hydrophobized by the introduction of methyl groups into silicon atoms in the silicon oxide film, and moisture adsorption is suppressed.

That is, the surface layer according to the present invention includes a silicon oxide film containing carbon. The silicon oxide film has a bending vibration peak indicating the presence of a Si—CH ₃ bond in an infrared absorption spectrum, and the silicon oxide having the number of carbon atoms bonded to a silicon atom. Ratio to the total number of carbon atoms, silicon atoms and oxygen atoms in the film, that is, [(number of carbon atoms bonded to silicon atom) × 100 / (carbon atoms in silicon oxide film) Number + number of silicon atoms + number of carbon atoms)] is 40 atomic% or more and 72 atomic% or less.

Furthermore, the surface layer according to the present invention has a ratio of the number of oxygen atoms bonded to silicon atoms to the number of silicon atoms, that is, [(number of oxygen atoms bonded to silicon atoms) / (silicon Number of atoms)] (O / Si) is 0.85 or more and 1.2 or less.
By making the carbon atom content of the surface layer and the O / Si ratio within the above numerical range, the adhesion between the surface layer of the intermediate transfer member and the toner is reduced to improve the transfer efficiency and repeat image output. Also, good cleaning properties can be maintained. Further, since the surface layer does not become hard, cracks are unlikely to occur during long-term use of the intermediate transfer member.

The silicon oxide film according to the present invention is preferably formed by, for example, a low temperature vacuum plasma CVD (chemical vapor deposition) method using an organosilicon compound and an inert gas as raw materials. The low-temperature vacuum plasma CVD method does not require heating of the base material layer, can form a film at a low temperature of 10 ° C. to 70 ° C., and has a predetermined carbon atom content and O / Si ratio. It can be easily controlled within the range. In the case of forming a film by a low-temperature vacuum plasma CVD method, the inside of the film formation chamber (vacuum chamber) before film formation is kept at a vacuum degree of 1 × 10 ⁻³ Pa or more and 1 × 10 ⁻⁵ Pa or less for a certain period of time, It is more preferable to exclude oxygen in the film forming process and to thoroughly reduce the oxygen content in the source gas.

  As the low-temperature vacuum plasma CVD method, a capacitively coupled plasma CVD method, an inductively coupled plasma CVD method, an ECR (electron cyclotron resonance) plasma CVD method, or the like can be used. Among these, it is preferable to use an inductively coupled plasma CVD method. This is because uniform and high-density plasma is generated, an extremely high quality film can be produced, and the adhesion to the substrate is excellent. In addition, since plasma is generated at a position sufficiently away from the base material layer, plasma damage to the resin and the rubber base material is extremely small. Note that, since the film formation is performed while rotating the base material layer at a constant speed, the surface layer can be formed with a uniform film thickness even with a thin film of 1000 nm or less.

As the organosilicon compound as the source gas, it is preferable to use a low molecular weight disiloxane compound having a Si—CH ₃ bond in the molecule, such as hexamethyldisiloxane, tetramethyldisiloxane, triethyltrimethyldisiloxane and the like. This is because it is sufficiently decomposed in vacuum plasma and is easy to form a film.
As the inert gas, argon gas, helium gas, neon gas, krypton gas, xenon gas, or the like can be used.

The elemental composition of the surface layer was analyzed using an X-ray photoelectron spectroscopy (XPS) apparatus (manufactured by ULVAC-PHI, trade name “PHI1800 type”). In order to avoid the influence of surface layer deposits (impurities), argon etching was performed to a depth of 20 nm from the outermost surface, then MgKα (200 W) was used as an X-ray source, and measurement was performed on a region with a diameter of 0.8 mm. (Measured degree of vacuum 1 × 10 ⁻⁶ Pa at measurement). In the obtained spectrum, the surface atomic concentration% of carbon, oxygen, and silicon was determined from the peak due to the binding energy of C1s orbital, O1s orbital, and Si2p orbital. Furthermore, the abundance ratio O / Si of oxygen atoms forming bonds with silicon atoms to silicon atoms was calculated from the surface atomic concentration%.

Presence of the Si—CH ₃ bond can be confirmed from the bending vibration peak of Si—CH ₃ (near 1250 cm ^{−1 to} 1260 cm ⁻¹ ) in the infrared absorption spectrum of the surface layer measured by a Fourier transform infrared spectrometer. . Moreover, the presence of Si—C bonds can be confirmed from the stretching vibration peak of Si—C (around 810 cm ^{−1 to} 840 cm ⁻¹ ). The presence of Si—O bonds can be confirmed from the stretching vibration peak of Si—O (around 1020 cm ^{−1 to} 1090 cm cm ⁻¹ ).
The infrared absorption spectrum of the surface layer of the intermediate transfer belt was measured by the ATR method using a Fourier transform infrared spectrometer (trade name “SpectrumOne” manufactured by PerkinElmer) (measurement atmosphere: temperature 23 ° C., relative humidity 55). %).

The surface layer of the intermediate transfer member has a surface that free energy is in the range of 25 mJ / m ² or more 40 mJ / m ² or less, and reducing non-electrostatic adhesion force between the toner, an external additive, paper dust, This is preferable from the viewpoint of the effect of suppressing the adhesion of dirt such as shaving powder and discharge products of the photoreceptor. In particular, reducing the adhesion force with the toner is important for improving the transfer efficiency. In addition, the surface free energy of the surface layer being in the above range is considered to largely depend on the carbon atom content and the O / Si ratio as well as the presence of Si—CH ₃ bonds in the surface layer.

The surface free energy of the surface layer of the intermediate transfer member can be calculated by the “Kitazaki and Hata method” described in Non-Patent Document 1. First, the contact angle on the surface of the intermediate transfer belt was measured using water, n-hexadecane, and diiodomethane as standard liquids (measuring environment: temperature 23 ° C., relative humidity 55%). Next, using each contact angle measurement result, the surface free energy was obtained from the “expanded Fowkes equation” according to the theory of Kitazaki and Hata (Non-patent Document 1).
A contact angle meter (manufactured by Kyowa Interface Science, trade name “DM-501”) was used for measurement, and an analysis software (trade name “FAMAS”, manufactured by Kyowa Interface Science) was used for surface free energy analysis.

  Further, the hardness of the surface layer of the intermediate transfer member is preferably in the range of 1.5 GPa or more and 3 GPa or less in terms of nanoindenter hardness from the viewpoint of suppressing the occurrence of cracks and scratches during durable use and cleaning properties. By setting the nanoindenter hardness, it becomes easy to clean discharge products and dirt adhering to the surface of the intermediate transfer member, and the surface free energy can be maintained in the above-mentioned range. With regard to this mechanism, it is presumed that the discharge product and dirt are removed because the surface layer is slightly scraped by rubbing with the cleaning blade.

The nanoindenter hardness of the surface of the intermediate transfer belt was measured as follows.
A scanning probe microscope (manufactured by Digital Instruments, trade name “NanoScope III”) and a nano indenter (manufactured by Heiditron, trade name “TRIBOSCOPE”) were used as measuring instruments. Further, a Berkovich indenter was used as the hardness measurement indenter, and the measurement load was 30 μN. (Measurement atmosphere: temperature 23 ° C., relative humidity 55%). The nanoindenter hardness was determined from the obtained load-displacement curve.

The film thickness of the surface layer of the intermediate transfer member is preferably in the range of 50 nm to 1000 nm. This is because by making the above numerical range, it is difficult to be influenced by the surface roughness of the base material layer or the intermediate layer or the residual stress.
The film thickness of the surface layer formed on the surface of the intermediate transfer belt was measured using a spectroscopic film thickness meter (trade name “TFW-100” manufactured by Lambda Vision).

Since the surface layer of the intermediate transfer member uses a low temperature vacuum plasma CVD method, a uniform electric resistance can be obtained as compared with wet coating.
In the measurement of charge potential attenuation of the surface layer of the intermediate transfer member, the half-life of the saturated charge potential is preferably 3 seconds or more and 20 seconds or less from the viewpoint of transfer efficiency.
The saturation charge potential decay time on the surface of the intermediate transfer belt was measured by cutting the intermediate transfer belt into 50 × 50 mm square and using an electrostatic charge test apparatus (trade name “EPA-8300A” manufactured by Kawaguchi Electric Mfg. Co., Ltd.). The measurement conditions are shown in Table 1.

  After the sample stage (diameter 236 mm) on which the sample was fixed was rotated at a rotation speed of 1100 rpm, the surface of the sample was charged with a scorotron charger for 30 seconds, and the charged potential of the surface at that time was defined as a saturated charged potential. Next, charging of the scorotron charger was stopped, and the decay time of the saturated charging potential was measured while rotating the sample stage. From the obtained time-charge potential curve, the time until the saturation charge potential was halved was defined as the half-life.

<Intermediate transfer material intermediate layer>
For the intermediate layer of the intermediate transfer member according to the present invention, a resin, thermoplastic elastomer, vulcanized rubber, or the like in which various conductive agents described above are dispersed may be used as a material for the base layer. Alternatively, an inorganic oxide thin film such as silicon dioxide, silicon monoxide, aluminum oxide, titanium oxide, magnesium oxide, or zinc oxide, or a metal thin film such as aluminum or titanium may be used.

<Resistance of intermediate transfer member>
The volume resistivity of the intermediate transfer member is preferably in the range of 1 × 10 ⁶ Ωcm to 1 × 10 ¹² Ωcm. This is because high transfer efficiency can be maintained by setting the above numerical range.

<Image forming apparatus>
FIG. 2 is a schematic configuration diagram illustrating the electrophotographic tandem full-color image forming apparatus used in the first embodiment.
The image forming apparatus includes an image forming unit 1a that forms a yellow image, an image forming unit 1b that forms a magenta image, an image forming unit 1c that forms a cyan image, and a black image. The image forming unit 1d to be formed includes four image forming units. These four image forming units are arranged in a line at regular intervals.

  In each of the image forming units 1a, 1b, 1c, and 1d, photosensitive drums 2a, 2b, 2c, and 2d are installed as image carriers. Around each photosensitive drum 2a, 2b, 2c, 2d, charging members 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, and drum cleaning devices 6a, 6b, 6c, 6d are respectively installed. Yes. Exposure devices 7a, 7b, 7c, and 7d are installed above the charging members 3a, 3b, 3c, and 3d and the developing devices 4a, 4b, 4c, and 4d, respectively. Each developing device 4a, 4b, 4c, 4d contains yellow toner, cyan toner, magenta toner, and black toner, respectively.

Each photosensitive drum is a negatively charged organic photoreceptor in this embodiment, and has a photosensitive layer (not shown) on a drum base (not shown) such as aluminum, and a predetermined process is performed by a driving device (not shown). Driven by speed.
Each charging member uniformly charges the surface of each photosensitive drum to a predetermined polarity and potential by a charging bias applied from a charging bias power source (not shown).

  The exposure apparatuses 7a, 7b, 7c, and 7d output laser light modulated in accordance with time-series electric digital pixel signals of image information input from a host computer (not shown) from a laser output unit (not shown). To do. By exposing the surface of each photosensitive drum with the laser beam, an electrostatic latent image corresponding to image information is formed on the surface of each photosensitive drum charged by each charging member.

Each developing device attaches toner to an electrostatic latent image formed on each photosensitive drum and develops it (visualizes it) as a toner image. Here, each developing device uses a one-component contact developing device.
The toner image formed on each photosensitive drum passes through a nip portion (primary transfer portion) formed by contact between each photosensitive drum and the intermediate transfer member 8. In this process, a voltage (primary transfer) having a polarity opposite to the charging polarity of the toner is applied to the intermediate transfer body 8 from the primary transfer bias power supplies 9a, 9b, 9c, and 9d via the primary transfer rollers 5a, 5b, 5c, and 5d. Bias) is applied. Transfer (primary transfer) is performed from each photosensitive drum to the outer peripheral surface of the intermediate transfer member 8 by the electric field and pressure formed by the primary transfer bias. An elastic roller having a volume resistivity of 10 ⁷ to 10 ⁹ Ωcm and a rubber hardness of 30 ° (Asker C hardness meter) was used as the primary transfer roller.
Untransferred toner remaining on the photosensitive drums 2a, 2b, 2c, and 2d without the primary transfer is removed and collected by the drum cleaning devices 6a, 6b, 6c, and 6d.

The intermediate transfer member 8 is stretched between the driving roller 11, the secondary transfer counter roller 12, and the tension roller 13 (three are collectively referred to as “stretching roller”), and a motor (not shown) is connected to the intermediate transfer member 8. The drive roller 11 thus driven is rotated (moved) in the direction of the arrow (counterclockwise).
The driving roller 11 is provided with a high friction rubber layer on the surface layer for driving the intermediate transfer member 8, and the rubber layer is made conductive with a volume resistivity of 10 ⁵ Ωcm or less. The secondary transfer counter roller 12 forms a secondary transfer portion with the secondary transfer roller 15 via the intermediate transfer member 8. The secondary transfer counter roller 12 was provided with a rubber layer on the surface, and the rubber layer was made conductive with a volume resistivity of 10 ⁵ Ωcm or less. The tension roller 13 is made of a metal roller, applies a tension of a total pressure of about 60 N to the intermediate transfer member 8, and rotates following the intermediate transfer belt 8. The drive roller 11 and the secondary transfer counter roller 12 are electrically insulated.

As the secondary transfer roller 15, an elastic roller having a volume resistivity of 1 × 10 ⁷ to 1 × 10 ⁹ Ωcm and a rubber hardness of 30 ° (Asker C hardness meter) was used. The secondary transfer roller 15 is pressed with a total pressure of 39.2 N against the secondary transfer counter roller 12 via the intermediate transfer body 8, and rotates following the rotation of the intermediate transfer body 8. A secondary transfer bias power source (high voltage power source) 19 is connected to the secondary transfer roller 15 so that a voltage of −2.0 kV to +5.0 kV can be applied.
Outside the intermediate transfer belt 8, an intermediate transfer body cleaning device 75 that removes and collects transfer residual toner remaining on the surface of the intermediate transfer belt 8 is installed. A fixing device 17 having a fixing roller 17a and a pressure roller 17b is installed on the downstream side of the transfer direction of the transfer material in the secondary transfer portion where the secondary transfer counter roller 12 and the secondary transfer roller 15 abut. Yes.

Next, an image forming operation by the above-described image forming apparatus will be described.
When an image forming operation start signal is issued, transfer materials (paper) are sent out one by one from a cassette (not shown) and conveyed to registration rollers (not shown). At that time, the registration roller is stopped, and the leading edge of the transfer material stands by just before the secondary transfer portion.
On the other hand, in each image forming unit, when an image forming operation start signal is issued, each photosensitive drum is rotationally driven at a predetermined process speed, and is uniformly charged to a negative polarity by each charging member. Each exposure apparatus converts a color-separated image signal input from a host computer (not shown) into an optical signal (laser light) by a laser output unit (not shown), and charges each photosensitive device. Each drum is scanned and exposed to form an electrostatic latent image.
Then, a yellow toner is attached to the electrostatic latent image formed on the photosensitive drum 2a by the developing device 4a to which a developing bias having the same polarity as the charging polarity (negative polarity) of the photosensitive drum 2a is applied. Visualize as an image.

As for the surface potential of the photosensitive drum, the charge amount and the exposure amount are adjusted so that the potential after being charged by the charging member is −450 V, and the potential (image portion) after being exposed by the exposure device is −100 V, and the development bias Is -300V. Further, the process speed is 60 mm / sec, and the image forming width, which is the length in the direction perpendicular to the conveyance direction, is 215 mm. Further, the toner amount on the photosensitive drum in the solid image portion is set to 0.4 mg / cm ² , and the toner charge amount on the photosensitive drum is set to −40 μC / g.

This yellow toner image is primarily transferred onto the intermediate transfer member 8 at the primary transfer portion. Here, a portion where a toner image is transferred from each photosensitive drum or a position where the toner image is transferred facing each photosensitive drum is defined as a primary transfer portion. A plurality of primary transfer portions are provided on the intermediate transfer member 8 in a form corresponding to a plurality of image carriers.
The intermediate transfer member 8 onto which the yellow toner image has been transferred moves to the image forming unit 1b side. In the image forming unit 1b as well, the magenta toner image formed on the photosensitive drum 2b in the same manner as described above is superimposed and transferred onto the yellow toner image on the intermediate transfer member 8.

In the same manner, cyan and black toner images formed on the photosensitive drums 2c and 2d of the image forming units 1c and 1d are sequentially superimposed on the yellow and magenta toner images superimposed and transferred onto the intermediate transfer member 8 in the same manner. In addition, a full-color toner image is formed on the intermediate transfer member 8.
Then, the transfer material is conveyed to the secondary transfer portion by a registration roller (not shown) in accordance with the timing at which the front end of the full-color toner image on the intermediate transfer body 8 moves to the secondary transfer portion. A full-color toner image is secondarily transferred collectively to the transfer material by a secondary transfer roller 15 to which a secondary transfer bias (opposite polarity (positive polarity) with respect to toner) is applied.

The transfer material on which the full-color toner image is formed is conveyed to the fixing device 17, and the full-color toner image is heated and pressed at the fixing nip portion between the fixing roller 17a and the pressure roller 17b to heat the surface of the transfer material. After fixing, the sheet is discharged to the outside, and a series of image forming operations is completed.
The primary transfer residual toner remaining on the photosensitive drums 2a, 2b, 2c, and 2d at the time of each primary transfer described above is collected by the drum cleaning devices 6a, 6b, 6c, and 4d, respectively. .
The secondary transfer residual toner remaining on the intermediate transfer belt 8 after the secondary transfer is removed from the intermediate transfer member 8 by the intermediate transfer member cleaning device 75.

Example 1
A method for producing a seamless belt-shaped intermediate transfer belt as an intermediate transfer member will be described.
<Example of production of intermediate transfer belt>
<Example of production of substrate layer used for intermediate transfer belt>
As the raw material for the base layer, the material mixture shown in Table 2 was pre-stirred for 10 minutes with a wing mixer.

Next, using a three-roll mill, the roll was kneaded for 1 hour with warm water at a temperature of 60 ° C. to obtain a dispersion.
The obtained dispersion was defoamed using a closed-type defoaming mixer, then developed inside a cylindrical mold, and gradually heated to a temperature of 350 ° C. while rotating to evaporate the solvent. Finally, a polyimide resin seamless belt (thickness: 65 μm) as a base material layer was produced by heating at 350 ° C. for 30 minutes.
This polyimide resin seamless belt was used as the base material layer 1 of Example 1. The volume resistivity of the base material layer 1 was 2 × 10 ⁷ Ωcm (measurement voltage 100 V).

<Example of production of surface layer used for intermediate transfer belt>
FIG. 4 is a schematic view of an inductively coupled plasma CVD apparatus.
101 is a film forming chamber, 102 is an exhaust system, 103 is a gas introduction system, 104 is a magnetic field forming member, 105 is a seamless belt base material (that is, a base material layer of the seamless belt), 106 is a high-frequency power source, 107 is a matching unit, Reference numerals 108a and 108b denote rotational drive rollers.
Hereinafter, a film forming method using an inductively coupled plasma CVD apparatus will be described.

First, the seamless belt base material 105 is installed on the rotation drive rollers 108a and 108b, and the seamless belt base material 105 is rotated at a constant speed.
Next, the inside of the film forming chamber 101 is evacuated to a vacuum level of 1 × 10 ⁻³ Pa to 1 × 10 ⁻⁵ Pa by a vacuum pump (not shown) of the exhaust system 102, while maintaining a predetermined vacuum level for a certain period of time. The source gases 103 a and 103 b are introduced from the gas introduction system 103. The liquid raw material is sprayed in a mist form.
Then, a power of 13.56 MHz is applied to the magnetic field forming member 104 from the high frequency power source 106 by adjusting the matching unit 107. The magnetic field forming member 104 includes an induction coil. When high frequency power is applied, radio waves are generated from the induction coil, and plasma is generated from the magnetic field forming member 104. At this time, plasma (plasma generation region P) is generated at a position sufficiently away from the seamless belt substrate.
As described above, the reactive species in the plasma diffuses on the outer peripheral surface of the seamless belt substrate 105, and a surface layer is formed.
A carbon-containing silicon oxide film having a film thickness of 200 nm was formed on the surface of the base material layer 1 under the conditions described in Table 3 by the film formation method described above.

  On both edge portions of the inner peripheral surface of the seamless belt on which the surface layer is formed, a urethane rubber rib (width 5 mm, height 1 mm) that protrudes inward and restricts the axial movement of the seamless belt is continuously provided. The intermediate transfer belt of Example 1 in the present invention was prepared. Tables 7 and 8 show the configurations and characteristics of the intermediate transfer belts (Examples 1-1 to 1-7) manufactured in Example 1.

<Method for measuring surface resistivity and volume resistivity of intermediate transfer member>
The intermediate transfer belt was cut into a 60 × 60 mm square, and platinum electrodes were provided on the front and back surfaces by sputtering. The electrode shape was such that the circular main electrode on the surface had a diameter of 25 mm, the ring electrode on the surface had an outer diameter of 50 mm, an inner diameter of 38 mm, and the circular electrode on the back surface had an outer diameter of 54 mm.
The measurement method is in accordance with JIS-K6911, using an ultrahigh resistance resistance meter (manufactured by ADC, trade name “R8340A”) and an ultrahigh resistance sample measuring box (manufactured by ADC, trade name “TR42”). The surface resistivity and volume resistivity of the transfer belt were measured. The measurement conditions were an applied voltage of 100 V or 10 V and a measurement time of 10 seconds (measurement atmosphere: temperature 23 ° C., relative humidity 55%).
The volume resistivity of the base material layer of the above intermediate transfer member was also measured by the same method.
Table 8 shows the surface resistivity and volume resistivity of the intermediate transfer belt in Example 1.
The intermediate transfer belt in Example 1 was incorporated into the image forming apparatus shown in FIG. 2, and secondary transferability and durability tests were evaluated by the following durability evaluation method. The toner used was a non-magnetic single-component chemical toner having a particle size of 6 μm and having a substantially spherical shape containing a wax component, produced by a suspension polymerization method.

<Durability evaluation method>
Using letter-size recording paper (basis weight 75 g / m ² ) in an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%, the image for evaluation with an image ratio of 5% was continuously output 100,000 sheets in a horizontal feed. Then, the intermediate transfer belt was taken out.
A solid image of the secondary color (blue) is output, the transfer residual toner remaining on the intermediate transfer member and the unfixed toner on the recording paper are sucked with air, and the following weight is obtained from the weight of the toner sampled by the filter. The secondary transfer efficiency was obtained from the calculation formula.
Secondary transfer efficiency (%) = {(unfixed toner on recording paper) / (unfixed toner on recording paper + transfer residual toner on intermediate transfer member)} × 100
<Evaluation of secondary transferability>
Secondary transferability was evaluated according to the rank described in Table 4.

<Durability test evaluation>
The surface of the intermediate transfer belt after the durability test was observed with a microscope (manufactured by Keyence, trade name “VHX-1000”), and the durability test was evaluated according to the ranks shown in Table 5.
Table 8 shows the results of secondary transferability and durability tests in Examples 1-1 to 1-7.

(Comparative Example 1-1 and Comparative Example 1-2)
Except for using the base material layer 1 of Example 1 and using a mixed gas of hexamethyldisiloxane / argon / oxygen (argon / oxygen = 99/1) (flow rate ratio = 5/95) as a raw material gas for the surface layer, An intermediate transfer belt of Comparative Example 1-1 was produced in the same manner as in Example 1. Further, an intermediate transfer belt of Comparative Example 1-2 was produced by the same production method in the configuration shown in Table 7. Tables 7 and 8 show the configurations and characteristics of the intermediate transfer belts manufactured in Comparative Examples 1-1 and 1-2.

  The intermediate transfer belt in Comparative Example 1-1 and Comparative Example 1-2 was incorporated in the image forming apparatus shown in FIG. 2, and durability evaluation was performed in the same manner as in Example 1. Table 8 shows the results of the secondary transferability and durability test.

(Comparative Example 2)
Example 1 except that the substrate layer 1 of Example 1 was used and a mixed gas (flow rate ratio = 5/95) of monosilane / argon / oxygen (argon / oxygen = 95/5) was used as the raw material gas for the surface layer. An intermediate transfer belt of Comparative Example 2 was produced in the same manner as described above. Tables 7 and 8 show the configuration and characteristics of the intermediate transfer belt manufactured in Comparative Example 2.
The intermediate transfer belt in Comparative Example 2 was incorporated into the image forming apparatus shown in FIG. 2, and durability was evaluated by the same method as in Example 1. Table 8 shows the results of the secondary transferability and durability test.

(Comparative Example 3)
Using the base material layer 1 of Example 1, silicon dioxide was formed as a surface layer with a target material of silicon dioxide by an electron beam heating vacuum deposition method to a thickness of 200 nm, and an intermediate transfer belt of Comparative Example 3 was produced. . Tables 7 and 8 show the configuration and characteristics of the intermediate transfer belt manufactured in Comparative Example 3.
The intermediate transfer belt in Comparative Example 3 was incorporated into the image forming apparatus shown in FIG. 2, and durability evaluation was performed in the same manner as in Example 1. Table 8 shows the results of the secondary transferability and durability test.

(Example 2)
<Example of production of substrate layer used for intermediate transfer belt>
The materials listed in Table 6 were used as the raw material for the base layer.

In the same manner as in Example 1, a polyimide resin seamless belt (thickness: 65 μm) as a base material layer was produced. This polyimide resin seamless belt was used as the base material layer 2 of Example 2. The volume resistivity of the base material layer 2 was 2 × 10 ⁴ Ωcm (measurement voltage 10 V).

<Example of production of surface layer used for intermediate transfer belt>
Example 1 except that the base material layer 2 of Example 2 was used and a 1,1,3,3-tetramethyldisiloxane / argon mixed gas (flow rate ratio = 5/95) was used as the raw material gas for the surface layer. The intermediate transfer belt of Example 2 was produced in the same manner as described above.
Tables 7 and 8 show the configurations and characteristics of the intermediate transfer belts (Example 2-1 to Example 2-6) manufactured in Example 2. The intermediate transfer belt in Example 2 was incorporated in the image forming apparatus shown in FIG. 3 described below, and durability evaluation was performed in the same manner as in Example 1. Table 8 shows the results of the secondary transferability and durability test.

<Image forming apparatus>
FIG. 3 is a schematic configuration diagram showing an electrophotographic tandem type full-color image forming apparatus used in Example 2 and Example 3 described later. Differences from the image forming apparatus (FIG. 2) used in Example 1 will be described below.
The image forming apparatus shown in FIG. 3 does not have the primary transfer roller (5a, 5b, 5c, 5d) in FIG. 2, and the primary transfer bias is supplied from the intermediate transfer member bias power source 20 connected to the tension roller 13. Is applied. In this way, +300 V is applied as the primary transfer bias, and the surface potential of the intermediate transfer member becomes approximately +300 V, whereby the toner image formed on each photosensitive drum is primarily transferred to the intermediate transfer member 8. . That is, in the image forming apparatus shown in FIG. 3, primary transfer for transferring a toner image from each photosensitive drum to the intermediate transfer member 8 is performed without using a primary transfer roller.

(Example 3)
Except using the base material layer 1 of Example 1 and using 1,1,1-triethyl-3,3,3-trimethyldisiloxane / argon mixed gas (flow rate ratio = 5/95) as a raw material gas for the surface layer Produced the intermediate transfer belt of Example 3 in the same manner as in Example 1.
Tables 7 and 8 show the configurations and characteristics of the intermediate transfer belts (Examples 3-1 to 3-7) manufactured in Example 3.
The intermediate transfer belt in Example 3 was incorporated into the image forming apparatus shown in FIG. 3, and durability was evaluated in the same manner as in Example 1. Table 8 shows the results of the secondary transferability and durability test.
As shown in Tables 7 and 8, it was found that an intermediate transfer member having good secondary transfer properties and excellent durability can be obtained by using the configuration and characteristics of the surface layer according to the present invention.

1a, 1b, 1c, 1d Image forming units 2a, 2b, 2c, 2d Photosensitive drum (image carrier)
3a, 3b, 3c, 3d Charging member (charging means)
4a, 4b, 4c, 4d Developing device (developing means)
5a, 5b, 5c, 5d Primary transfer roller (transfer means)
6a, 6b, 6c, 6d Drum cleaning device (image carrier cleaning means)
7a, 7b, 7c, 7d Exposure apparatus (exposure means)
8 Intermediate transfer body (intermediate transfer belt)
8a Intermediate transfer member surface layer 8b Intermediate transfer member base layer 8c Intermediate transfer member intermediate layers 9a, 9b, 9c, 9d Primary transfer bias power source 11 Driving roller 12 Secondary transfer counter roller 13 Tension roller 15 Secondary transfer Roller 17 Fixing device 17a Fixing roller 17b Pressure roller 19 Secondary transfer bias power source 20 Intermediate transfer member bias power source 75 Intermediate transfer member cleaning device 101 Film forming chamber (vacuum chamber)
102 Exhaust system 103 Gas introduction system 103a, 103b Source gas 104 Magnetic field forming member 105 Seamless belt base material (base material layer of intermediate transfer member)
106 High-frequency power source 107 Matching units 108a and 108b Rotation drive roller P Plasma generation region

Claims (9)

An intermediate transfer body having a base material layer in which a conductive agent is dispersed and a surface layer,
The surface layer contains a silicon oxide film containing carbon,
The silicon oxide film is
In the infrared absorption spectrum, it has a bending vibration peak of Si—CH ₃ ,
The ratio of the number of carbon atoms bonded to the silicon atom to the total number of carbon atoms, silicon atoms and oxygen atoms in the silicon oxide film is 40 atom% or more and 72 atom% or less, and
An intermediate transfer member, wherein the ratio of the number of oxygen atoms bonded to a silicon atom to the number of silicon atoms is 0.85 or more and 1.2 or less. The intermediate transfer member according to claim 1 surface free energy of the intermediate transfer member surface layer of is 25 mJ / ^{m 2} or more 40 mJ / ^{m 2} or less.   The intermediate transfer member according to claim 1 or 2, wherein the surface layer of the intermediate transfer member has a nanoindenter hardness of 1.5 GPa or more and 3 GPa or less.   The intermediate transfer member according to any one of claims 1 to 3, wherein a thickness of a surface layer of the intermediate transfer member is 50 nm or more and 1000 nm or less.   The intermediate transfer member according to any one of claims 1 to 4, wherein a half-life of a saturation charging potential of the surface layer of the intermediate transfer member is 3 seconds or more and 20 seconds or less.   The intermediate transfer member according to any one of claims 1 to 5, wherein the surface layer of the intermediate transfer member is produced by a low temperature vacuum plasma CVD method using an organosilicon compound as a raw material.   The surface layer of the intermediate transfer member is selected from the group consisting of hexamethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, and 1,1,1-triethyl-3,3,3-trimethyldisiloxane. The intermediate transfer member according to any one of claims 1 to 6, which is produced by a low temperature vacuum plasma CVD method using an organosilicon compound as a raw material.   The surface layer of the intermediate transfer member is selected from the group consisting of hexamethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, and 1,1,1-triethyl-3,3,3-trimethyldisiloxane. The intermediate transfer member according to any one of claims 1 to 6, which is produced by an inductively coupled plasma CVD method using an organic silicon compound as a raw material. An image forming apparatus comprising the intermediate transfer member according to claim 1.