JP2000221799A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extremely increase the transfer efficiency from a first image carrying body to an intermediate transfer body and the transfer efficiency from the intermediate transfer body to a second image carrier body by forming a silica coating layer into the intermediate transfer body. SOLUTION: The intermediate transfer body has a silica coating layer. The silica coating layer is produced by applying a coating material containing a polysilazane on the surface of the intermediate transfer body, and by heat treating the intermediate transfer body at 100 to 400 deg.C for 15 to 300 min. The polysilazane is prepared by properly reacting or modifying the structure expressed by the formula so as to add characteristics excellent in transfer property, wear strength and contamination resistance as the outermost layer of the intermediate transfer body. In the formula, each of Ra to Rc is a hydrogen atom, alkyl group, cycloalkyl group, alkenyl group or the like. Modified polysilazanes include all polysilazanes having the polysilazane of the structure expressed by the formula as the main frame, and for example, metal carboxylate-added polysilazane produced by the reaction of the polysilazane and a metal carboxylic acid containing one or more kinds of metals such as Ni and Ti can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system, and more particularly, to a method in which a toner image formed on a first image carrier is temporarily transferred to an intermediate transfer member and then transferred to a second image carrier. And an image forming apparatus such as a copying machine, a printer, a facsimile, etc., for obtaining an image formed product by further transferring the image on an image carrier.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member includes:
A color image forming apparatus, a multi-color image forming apparatus, or a color image forming apparatus that sequentially transfers a plurality of component color images of color image information or multi-color image information and outputs an image formed product by combining and reproducing a color image or a multi-color image. This is effective as an image forming apparatus having a forming function and a multicolor image forming function.

In a color electrophotographic apparatus having an image forming apparatus using an intermediate transfer member, a second image support is stuck or adsorbed on a transfer drum, which is a conventional technique, and the first image support is placed on the second image support. A color electrophotographic apparatus having an image forming apparatus for transferring an image from the
It is superior to the transfer method described in JP 01960 in the following points. That is, there is little color shift at the time of superimposing the toner images of each color. Next, as shown in a schematic diagram of an example of an image forming apparatus using an intermediate transfer belt as the intermediate transfer body in FIG. 1, any processing and control (for example, gripping by a gripper, suctioning) by a second image carrier , Having a curvature, etc.), the image can be transferred from the intermediate transfer member, so that the second image carrier can be selected in various ways.

[0004] For example, it is possible to select from thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper), and transfer regardless of the width or length of the second image carrier. It is possible. Furthermore, it is possible to deal with envelopes, postcards, label paper, and the like.

Further, since the rigidity of the intermediate transfer member is excellent, dimensional accuracy such as dents, distortion, deformation and the like hardly occurs due to repeated use, so that the frequency of replacing the intermediate transfer member can be reduced.

As described above, due to the advantages of using the intermediate transfer member, a color copying machine, a color printer, and the like using the image forming apparatus have already started operating in the market.

However, when the image forming apparatus using the intermediate transfer member is actually used repeatedly, the following problems still remain.

In order to increase the transfer efficiency from a first image carrier, for example, a photosensitive drum to an intermediate transfer member, and from the intermediate transfer member to a second image carrier, for example, paper or an OHP sheet, For example, when using a mixture of a large amount of highly lubricating powder for the binder of the outermost layer of the intermediate transfer body using a combination of only the outermost layer and the elastic layer, the transfer efficiency is improved, but the binder having high adhesiveness is used. Even in the case where is used, the adhesion to the elastic layer may not be good. For this reason, although the durability of about 30,000 to 40,000 sheets is maintained even in this state, if the durability is further extended, the surface layer may be peeled off or cracked from the elastic layer. In some cases, the continuity is not sufficient, and the image is not sufficiently transferred to cause unevenness of the image, or the cracked portion is not sufficiently transferred, and the cracked surface state is transferred to the image as it is. This makes the intermediate transfer member 3
It has to be replaced every ~ 40,000 sheets, which may lead to high running costs.

In addition, when a mixture of a large amount of highly lubricating powder in the outermost layer binder is used, the bleeding material from the elastic layer passes through the interface between the binder and the highly lubricating powder, and the photosensitive member and the like are removed. In some cases, resulting in image defects.

[0010] On the other hand, there has been considerably disclosed an invention which uses fluorine and silicone as materials for the surface layer of an intermediate transfer member and has excellent releasability. For example, in JP-A-57-8569, an intermediate transfer member treated with a fluorine-containing polymer compound,
JP-A-57-163264, JP-A-59-9
No. 1465 and JP-A-6-301223 disclose an intermediate transfer member using a fluorine-based rubber and an elastomer, and JP-A-58-90654 and JP-A-5-40417.
In the publication, many disclosures such as an intermediate transfer member using a fluorine-based resin on the surface are disclosed. In the case of silicone,
JP-A-7-23975, JP-A-57-164773 and JP-A-59-50473 disclose an intermediate transfer member comprising a silicone rubber surface layer, and a device disclosed in JP-A-5-460.
No. 35 discloses an intermediate transfer member coated with a liquid silicone compound. The present inventors conducted additional experiments on some of these inventions and confirmed the performance thereof, but could not obtain the effects as claimed and described by the inventions.

If these fluorine-based or silicone-based compounds are used for the surface layer, they are tentatively low surface energy compounds, so they have better transferability and releasability than other surface layer materials. Has an effect on toner contamination on the surface, toner filming, and the like. However, the intended purpose of the present inventors is to provide a long-life intermediate transfer body having a life equivalent to that of the main body having the intermediate transfer body, in other words, a long-life intermediate transfer body requiring no replacement. The intermediate transfer member is insufficient in transferability after durability and surface contamination resistance.

On the other hand, Japanese Patent Application Laid-Open No. Hei 7-234592 discloses an intermediate transfer member having fine particles of silica or fluororesin fixed thereon, but these surface layers are formed of a discontinuous film of particles. Since the adhesive step is performed, the adhesive strength is low, so that substantially high durability cannot be obtained.

However, the present invention proposes an image forming apparatus using a new intermediate transfer member which has solved the above-mentioned problems.

[0014]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
An object of the present invention is to provide an image forming apparatus in which the transfer efficiency from the image carrier to the intermediate transfer member and the transfer efficiency from the intermediate transfer member to the second image carrier are extremely high.

Another object of the present invention is to provide a second image carrier, such as paper or an OHP sheet, which has a uniform and uniform image quality free from transfer failure of a minute portion of an image, that is, without a so-called hollow image. An object of the present invention is to provide an image forming apparatus which can be achieved without depending on the type.

Still another object of the present invention is to maintain the same characteristics as those in the initial stage without changing the characteristics of the intermediate transfer member even when the intermediate transfer member is subjected to severe durability by repeated use. It is an object of the present invention to provide an image forming apparatus which realizes uniform conductivity and transferability without causing a layer constituting the layer and peeling or cracking between layers.

A further object of the present invention is to provide an image forming apparatus which does not cause filming due to toner adhesion to the surface of an intermediate transfer member, does not adversely affect an organic photosensitive member, and has a long photosensitive member life. It is in.

Another object is to set a high transfer bias to increase the transfer efficiency when transferring from the first image bearing member to the intermediate transfer member and when transferring from the intermediate transfer member to the second image bearing member. An object of the present invention is to provide an image forming apparatus which does not generate a leak even when the image forming operation is performed.

[0019]

According to the present invention, there is provided an image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and further transferring the image onto a second image carrier. And an image forming apparatus in which the intermediate transfer member has a silica coating layer.

[0020]

Embodiments of the present invention will be described below in detail.

The silica coating layer of the present invention is obtained by applying a coating containing polysilazane to the outermost surface of the intermediate transfer member and further subjecting the intermediate transfer member to heat treatment at 100 to 400 ° C. for 15 to 300 minutes. Obtainable.

As for the chemical reaction formula, the conversion reaction of polysilazane to silica follows the following formulas (1) and (2).

[0023]

Embedded image

The polysilazane used in the present invention is obtained by reacting and modifying the following structural formula (A) in a timely manner to give, as the outermost layer of the intermediate transfer member, excellent properties of transferability, abrasion strength and stain resistance. It is.

[0025]

Embedded image

In the formula, R ^a , R ^b and R ^c represent a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkylsilyl group, an alkylamino group or an alkoxy group.

In the present invention, the modified polysilazane includes all having a main skeleton of polysilazane of the structural formula (A), and is not limited to the following examples.

As the modified polysilazane, for example, N
i, Ti, Pt, Co, Fe, Al, Rh, Ir, Pd
And metal silicic acid-added polysilazane obtained by reacting a metal carboxylic acid and polysilazane (A) containing at least one metal selected from the group consisting of: Also, A
Polysilazane with fine metal particles to which fine metal particles of u, Ag, Pd, and Ni are added. Further, a silicon alkoxide-added polysilazane represented by the following structural formula (B) and obtained by heating and reacting a silicon alkoxide and polysilazane (A) is exemplified.

[0029]

Embedded image

Wherein R ¹ , R ² , R ³ and R ⁴ are a hydrogen atom,
R ¹ , R ² , R ^3, and R ⁴ may be the same atoms or groups, or may be different from each other.

Further, an alcohol having a boiling point of 150 ° C. or less, such as butanol, hexanol, octanol, nonanol, methoxyethanol, ethoxyethanol, furfurylethanol, ethylene glycol, diethylene glycol, and glycerin, is reacted with polysilazane (A). Alcohol-added polysilazane.

Further, an acetylacetonato complex-added polysilazane obtained by reacting an acetylacetonato complex containing Ni, Pt, Al or the like with polysilazane (A) may be mentioned.

The coating containing polysilazane of the present invention can be obtained by dispersing and dissolving one or both of the polysilazane and the modified polysilazane by selecting an appropriate solvent.

Examples of the solvent include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbon solvents, halogenated methanes, halogenated ethanes, halogenated benzenes and other halogenated hydrocarbons, aliphatic ethers, and aliphatic hydrocarbons. Ethers such as cyclic ethers can be used. Preferred solvents are
Halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane, tetrachloroethane, ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1,2-dioxyethane, dioxane, dimethyl dioxane, Ethers such as tetrahydrofuran and tetrahydropyran, pentahexane, isohexane, methylpentane, heptane, isoheptane, octane, isooctane, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, hydrocarbons such as benzene, toluene, xylene, ethylbenzene, etc. is there. When these solvents are used, two or more solvents may be mixed in order to adjust the solubility of polysilazane and the evaporation rate of the solvent.

The amount of polysilazane in the coating must be selected according to the composition and surface properties of the object to be coated.
More preferably, it is 3 to 60% by weight.

The silica coating layer of the present invention may contain, for example, the following additives such as materials, powders and particles for the purpose of improving toner stain resistance and transferability.

For example, sols such as silica sol, zirconia sol, alumina sol and titania sol: silica such as silica sand, quartz, novaculite, and diatomaceous earth: synthetic amorphous silica: kaolinite, mica, talc, wollastonite, asbestos, Silicates such as calcium silicate and aluminum silicate: glass powder, glass spheres, hollow glass spheres, glass flakes, foamed glass spheres and other glass bodies: boron nitride, boron carbide, aluminum nitride, aluminum carbide, silicon nitride, carbonized Non-oxide inorganic substances such as silicon, titanium boride, titanium nitride, and titanium carbide: calcium carbonate: metal oxides such as zinc oxide, alumina, magnesia, titanium oxide, beryllium oxide: barium sulfate, morphene disulfide,
Other inorganic substances such as tungsten disulfide and carbon fluoride: metal powders such as aluminum, bronze, lead, stainless steel, and zinc; and carbon bodies such as carbon black, coke, graphite, pyrolytic carbon, and hollow carbon spheres. .

In the present invention, more preferable additives include, for example, fluororubber, fluoroelastomer, carbon fluoride having fluorine bonded to graphite or graphite, and PT.
Powders of fluorine compounds such as resins such as FE, PVDF, ETFE, and PFA; silicone-based powders such as silicone resin particles, silicone rubber, and silicone elastomer;
Resins such as polyethylene, polypropylene, polystyrene, acrylic resin, polyamide resin, phenolic resin, epoxy resin and the like, powders of these compounds, mixtures, granular carbon such as spherical graphite, silica, alumina, titanium oxide, magnesium oxide, tin oxide, Inorganic powders such as iron oxide and the like, which may be surface-treated, or used alone or in combination.

Further, the shape and particle size of the added particles are not particularly limited, and any shape such as spherical, fibrous, plate-like, and irregular shapes can be used. Considering the surface properties and surface properties, the thickness is preferably 0.02 to 50 μm. These powders may be subjected to a surface treatment as needed within a range that does not impair lubricity. In addition, a dispersant can be used as long as it does not cause a problem in various properties.

In order for the present invention to exhibit desired effects,
The additive can occupy 0 to 50% by weight, preferably 0 to 40% by weight, based on the total solid content of the silica coating layer constituting the surface layer of the intermediate transfer member.

In order to apply a coating containing polysilazane to the intermediate transfer member and obtain the silica coating layer of the present invention, for example, the following method is used.

The paint is first applied uniformly to the outermost surface of the intermediate transfer member. As a coating method, a conventionally performed method, for example, a dip coating, a roll coating, a spray coating, a bar coating, a flow coating or the like is used.
Although it depends on the shape of the intermediate transfer member, preferred coating methods include dip coating and spray coating.

Next, the intermediate transfer member coated with the paint is
The heat treatment is performed in the range of 70 to 200 ° C, preferably in a range in which the properties of the material and the coating layer of the intermediate transfer member are not deteriorated by heating, for example, 160 ° C or less, more preferably in the range of 150 to 80 ° C.

When this heat treatment is carried out in a normal pressure or a pressurized steam atmosphere, the conversion of the intermediate coating material containing polysilazane into a silica coating layer is accelerated, and a more preferable result is obtained in the present invention. Can be

On the other hand, the above heat treatment is performed in a dry atmosphere, and then in the range of 1 to 5 atm and 10 to 100%
The silica coating layer can also be obtained by leaving it in an atmosphere within the relative humidity range of RH for 0.1 to 300 hours.

This is because the hydrolysis reaction of polysilazane in the paint accelerates with water vapor, and a substantial silica coating layer is completely formed.

On the other hand, after the heat treatment in a dry atmosphere, a suitable catalyst, for example, an acid or a base is preferable, and the type thereof is not particularly limited.
Diethylamine, monoethanolamine, diethanolamine, triethanolamine, di-n-butylamine, tri-n-butylamine, guanidine, piguanine, imidazole, 1,8-diazabicyclo- [5,
4,0] -7-undecene, 1,4-diazabicyclo-
Amines such as [2,2,2] -octane; alkalis such as sodium hydroxide, potassium hydroxide, lithium hydroxide, pyridine and aqueous ammonia; inorganic acids such as phosphoric acid; peracetic acid, acetic anhydride, propionic acid Lower monocarboxylic acids such as propionic anhydride, or anhydrides thereof, oxalic acid, fumaric acid, maleic acid, lower dicarboxylic acids such as succinic acid or anhydrides thereof, organic acids such as trichloroacetic acid; perchloric acid, Hydrochloric acid, nitric acid, sulfuric acid, sulfonic acid, patratoluenesulfonic acid, boron trifluoride and its complex with an electric donor, etc .; SnCl ₄ , ZnCl ₂ , FeCl ₃ , AlCl ₃ ,
Lewis acids such as SbCl ₃ and TiCl ₄ and complexes thereof can be used. A preferred catalyst is hydrochloric acid. The content of the catalyst is preferably 0.01 to 50% by weight, more preferably 0.1 to 20% by weight.

The intermediate transfer member coated with the above-mentioned polysilazane-containing paint is left or immersed in steam or distilled water containing these catalysts.
The hydrolysis reaction of the polysilazane can be promoted, and can also be converted to a substantial silica coating layer. The time for leaving or dipping is required to completely convert the polysilazane into the silica layer, and the time is 5 minutes to 3 minutes.
The range of 00 hours may be considered.

Polysilazane is subjected to heat treatment and hydrolysis
By the heat treatment, breaking of Si—R and NR (R represents a hydrogen atom or an alkyl group) bond and generation of a bond of Si—O occur. At this time, the polysilazane is mainly converted to silica having a Si—O bond, but a part of the polysilazane is also converted to silicon nitride having a Si—N bond. This Si-O and S
The i-N ratio is an indicator of the conversion of polysilazane to a silica coating layer. The higher the SiO / SiN ratio, the more the conversion to the silica coating layer is progressing.

The SiO / SiN ratio is determined by applying one or more treatment steps such as heat treatment, steam treatment, and immersion in distilled water containing a catalyst after applying a polysilazane-containing paint to the surface layer of the intermediate transfer member. The layer can be measured by infrared absorption measurement (IR measurement).

The IR characteristic absorption of SiO and SiN is about 11
60cm ^-1, reads the 840 cm ^-1 peak position. Further, the absorbance is calculated by the following formula: absorbance = log (Io / I).

Here, Io is the transmittance which becomes the base at the peak position, and I is the transmittance at the absorption peak, that is, the SiO / SiN ratio becomes as in the following formula (I).

[0053]

(Equation 1)

The range of the SiO / SiN ratio is preferably 1.1 or more, more preferably 1.3 or more.
If the ratio is less than 1.1, the conversion of the polysilazane paint coat layer into a silica coating layer is insufficient, and the durability of the intermediate transfer member is poor in abrasion resistance and scratch resistance.

The thickness of the silica coating layer is 0.01
It can be used in the range of ５０50 μm. In this range,
The coating layer is stably adhered to the lower layer, and can sufficiently follow the lower layer even if the lower layer has flexibility.
There is no cracking or cracking. If the thickness exceeds 50 μm, the coating layer becomes rigid, and when the intermediate transfer member is rotationally driven as a belt, it is easily cracked and lacks flexibility. If it is less than 0.01 μm, the substantial effect of the present invention cannot be obtained.

The silica coating layer of the present invention is most effective when used as the uppermost layer of an intermediate transfer member. On the other hand, it can be used for an intermediate layer to improve the adhesion between the layers, to maintain flexibility and to maintain flexibility. At this time, between the uppermost silica coating layer and the lower layer, or when using the silica coating layer as an intermediate layer, to improve the adhesion between the upper layer and the lower layer,
A surface treatment agent such as a primer may be applied.

Examples of the surface treatment agent include those using a silane compound, those using a titanate compound, those using an isocyanate resin, those using an epoxy resin, and those using a thermoplastic resin. Not something.

In order to further improve the effect of preventing bleeding from the lower layer, a bleeding preventing layer may be provided between the layers. Examples of the bleed prevention layer include, but are not limited to, resins having high barrier properties, such as polyamide, vinylidene chloride, polyethylene terephthalate, polyvinyl alcohol, and ethylene vinyl alcohol.

Further, a leak preventing layer may be provided to further improve the leak preventing effect. Examples of the leak prevention layer include, but are not limited to, resins having high leak resistance, such as polyamide, polystyrene, polyethylene, vinylidene chloride, polyethylene terephthalate, polyvinyl alcohol, and ethylene vinyl alcohol.

The silica coating layer, anti-bleed layer, anti-leak layer and surface protective layer of the present invention may be provided with conductivity. As a method for providing conductivity, conductive fillers and additives are used. No. Specifically, examples of the conductive filler include carbon, conductive titanium oxide, aluminum, and nickel, and examples of the additive include a surfactant and a perchlorate. Further, the conductive agent used for these is not limited to the above.

The intermediate transfer member used in the present invention has, for example, a roller shape having at least an elastic layer made of rubber, elastomer, or resin on a cylindrical conductive support, and one or more elastic layers formed on the elastic layer. The shape of the roller having the coating layer or the shape of the belt as shown in FIG. 2 and various aspects can be selected as desired and as necessary.
2 to 6 show examples of the configuration.

Considering the color misregistration of image superposition, the durability due to repeated use, and the cost of the intermediate transfer member and the apparatus, a more preferred embodiment of the present invention is a belt shape. 5 and 6 show an example of the intermediate transfer drum. 100 is a rigid cylindrical conductive support, 101
Denotes an elastic layer, 102 denotes an intermediate layer, and 103 denotes a silica coating layer. 2 to 4 show an example of the intermediate transfer belt, 101 denotes an elastic layer, 102 denotes an intermediate layer, and 103 denotes a silica coating layer. In FIG. 4, reference numeral 104 denotes a belt reinforcing layer. In these examples, the number of intermediate layers is one, but it is of course possible to provide one or more layers as shown in FIG.

As the cylindrical conductive support, metals and alloys such as aluminum, iron, copper and stainless steel, conductive resins in which carbon, metal particles and the like are dispersed, and the like can be used. Such a cylinder, a cylinder having a shaft penetrating the center of the cylinder, a cylinder having a reinforced interior, and the like may be used.

The rubber and elastomer used in the elastic layer of the intermediate transfer member used in the present invention include, for example, styrene-
Butadiene rubber, high styrene rubber, butadiene rubber,
Isoprene rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber,
Silicone rubber, fluorine rubber, nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber, norbornene rubber and the like, alone or in combination.

More preferred embodiments include, for example, ethylene-propylene copolymer, nitrile butadiene rubber,
Urethane rubber, nitrile rubber, acryl nitrile-containing acrylic rubber, polyamide elastomer or the like may be used alone or in combination with other rubbers and elastomers as described above.

The thickness of the elastic layer is preferably 0.1 mm or more, more preferably 0.15 mm or more, and particularly preferably 0.15 mm to 10 mm. The thickness of the upper layer is preferably a thin layer for further transmitting the flexibility of the lower elastic layer to the upper layer or the photoreceptor surface. The thickness of each layer other than the silica coating layer is specifically 1 mm. Below, and even 10
It is preferably 0 μm or less, particularly preferably 0.1 μm to 100 μm.

The volume resistivity of the intermediate transfer member used in the present invention is preferably from 10 ¹ to 10 ¹⁶ Ω · cm, and particularly preferably from 10 ² to 10 ¹³ Ω · cm.

[0068]

The present invention will be further described below with reference to examples. In addition, "part" in an Example shows a weight part.

(Production Example of Coating A) 2.2 g of n was added to 100 g of a 20% by weight xylene solution of perhydropolysilazane.
-Hexyl alcohol was added, and the mixture was stirred at room temperature for 2 to 3 hours to react and prepare a coating material A.

(Production Example of Paint B) To 100 g of a 20 wt% xylene solution of perhydropolysilazane, 30 g of a 1.0 wt% xylene solution of palladium (II) acetate, 70 g of xylene and 5 g of conductive titanium oxide were added. The mixture was stirred under the following conditions for 2 to 5 hours to cause a reaction, thereby preparing Paint B.

(Example 1) Elastic layer: conductive carbon black 10 parts paraffin oil 20 parts zinc oxide 5 parts vulcanizing agent 2 parts higher fatty acid 1.5 parts nitrile butadiene rubber (NBR) 40 parts EPDM 60 parts 2 Mixing was performed for 30 minutes while cooling with a roll to form a compound, which was used as an elastic layer.

Intermediate layer: 100 parts of polyester urethane 50 parts of conductive tin oxide DMF (solvent) 1000 parts were mixed to obtain an intermediate layer paint (1) to obtain an intermediate layer.

{Production of Intermediate Transfer Member} A rubber compound having the above composition was uniformly wound around a cylindrical mold to a thickness of 0.4 mm. Next, a polyethylene terephthalate yarn (twisted yarn, diameter 100 μm) coated on the surface with an adhesive was spirally wound on the compound so that the distance between adjacent fibers was 0.05 mm. On top of it, put the rubber compound of the above-mentioned compound extruded in a tube shape in advance,
By performing vulcanization and polishing, a rubber belt with a core having a thickness of 0.8 mm, a length of 250 mm, and an outer peripheral length (development free length) of 435 mm was obtained.

Next, after the intermediate layer is formed by spray coating with a coating for the intermediate layer, a coating A is further sprayed thereon to form a silica coating layer of the present invention.
An intermediate transfer member having an elastic layer, an intermediate layer and a surface coat layer was obtained.

Next, this intermediate transfer member was heated at 150 ° C. for 2 hours. Further, the intermediate transfer member was immersed in a solution obtained by adding 1.5% by weight of hydrochloric acid to distilled water for 2 to 3 hours to complete the conversion of the polysilazane coat layer to the silica coating layer by the coating material A, and then to sufficiently remove water. After removal and drying, an intermediate transfer member (1) of the present invention was obtained. At this time, the SiO / SiN ratio of the intermediate transfer member was 12.3, and the thickness of the silica coating layer was 0.3 μm.

This intermediate transfer body is cut into a 10 cm square,
350mm x 200 in an environment of a temperature of 23 ° C and a humidity of 65%
A 1 kV voltage is applied by a high-voltage power supply between the aluminum plate on the lower surface of the intermediate transfer body and the outermost layer of the intermediate transfer body, and the 1 kΩ voltage is connected in series with the power supply. The potential difference before and after the resistor was measured and converted into a current value, and further, the applied voltage (1 kV) and the resistance value of the intermediate transfer member were calculated from this current value.
0 ¹¹ Ω.

This intermediate transfer belt was mounted on the full-color electrophotographic apparatus shown in FIG. 1, and color misregistration, transferability and durability were evaluated.

The cleaning method for the intermediate transfer belt is a primary transfer simultaneous cleaning method using an elastic roller having a resistance of 1 × 10 ⁸ (Ω) for the cleaning charging member 7, and is used for continuous printing of 10,000 full-color images. Was done. At this time, the value of the current applied from the bias power supply 26 to the cleaning charging member 7 is +40 μA.

The electrophotographic apparatus of the present invention will be described with reference to FIG.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is repeatedly used as a first image carrier, and has a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. It is driven to rotate. As the first image carrier, it is preferable to use a photosensitive drum containing at least the outermost layer of a fine powder of tetrafluoroethylene resin (PTFE) because higher transfer efficiency can be obtained. This is considered to be because the surface energy of the outermost layer of the photosensitive drum is reduced by containing the fine powder of PTFE, and the releasability of the toner is improved.

The photosensitive drum 1 rotates the primary charger 2 during the rotation process.
, And is uniformly charged to a predetermined polarity and potential. Then, the exposure means 3 (not shown) is modulated according to a color separation / imaging exposure optical system of a color original image and a time-series electric digital pixel signal of image information. (E.g., a scanning exposure system using a laser scanner that outputs a laser beam) to form an electrostatic latent image corresponding to a first color component image (for example, a yellow color component image) of a target color image. Is done.

Next, the electrostatic latent image is developed by a first developing device (yellow developing device 41) with yellow toner Y as a first color. At this time, the developing units of the second to fourth developing units (the magenta developing unit 42, the cyan developing unit 43, and the black developing unit 44) are in the operation-off state and operate on the photosensitive drum 1. The yellow toner image of the first color is not affected by the second to fourth developing units.

The intermediate transfer member 20 is supported by rollers 64, 65 and 66 and is driven to rotate clockwise at the same peripheral speed as the photosensitive drum 1.

The first drum formed and supported on the photosensitive drum 1
During the process in which the yellow toner image of the color passes through the nip portion between the photosensitive drum 1 and the intermediate transfer body 20, the intermediate transfer is performed by the electric field formed by the primary transfer bias applied from the primary transfer roller 62 to the intermediate transfer belt 20. Belt 20
Are sequentially transferred (primary transfer) to the outer peripheral surface of.

The surface of the photosensitive drum 100 after the transfer of the first color yellow toner image corresponding to the intermediate transfer member 20 is cleaned by the cleaning device 13.

Hereinafter, similarly, the magenta toner image of the second color, the cyan toner image of the third color, and the black toner image of the fourth color are sequentially superimposed on the intermediate transfer member 20 and transferred to correspond to the target color image. Thus, a combined color toner image is formed.

Reference numeral 63 denotes a secondary transfer roller which corresponds to the secondary transfer opposing roller 64 and is supported in parallel with the intermediate transfer member 20.
Are arranged so as to be separated from each other on the lower surface of the.

First transfer from the photosensitive drum 1 to the intermediate transfer member 20
The primary transfer bias for the sequential superimposed transfer of the toner images of the fourth to fourth colors has a polarity (+) opposite to that of the toner and a bias power source 2
9. The applied voltage is, for example, +100 V
A range of -2 kV is preferred.

First transfer from the photosensitive drum 1 to the intermediate transfer member 20
The secondary transfer roller 63 can be separated from the intermediate transfer body 20 in the primary transfer step of the third color toner image.

The secondary transfer roller 63 transfers the composite color toner image transferred onto the intermediate transfer member 20 to a transfer material P such as a recording paper as a second image carrier.
And the intermediate transfer member 20 and the secondary transfer roller 6 from the paper feed roller 11 through the transfer material guide 10.
The transfer material P is fed at a predetermined timing to the contact nip with the transfer roller 3, and a secondary transfer bias is applied to the secondary transfer roller 63 from the power supply 28. With this secondary transfer bias, the composite color toner image is transferred (secondary transfer) from the intermediate transfer member 20 to the transfer material P as the second image carrier. The transfer material P to which the toner image has been transferred is introduced into the fixing device 15 and is fixed by heating.

After the image transfer to the transfer material P is completed, the cleaning charging member 7 is brought into contact with the intermediate transfer body 20 and is transferred to the transfer material P by applying a bias having a polarity opposite to that of the photosensitive drum 1. Instead, a charge having a polarity opposite to that of the photosensitive drum 1 is applied to the toner (transfer residual toner) remaining on the intermediate transfer body 20. 26 is a bias power supply.

The transfer residual toner is electrostatically transferred to the photosensitive drum 1 in the nip portion with the photosensitive drum 1 and in the vicinity thereof, thereby cleaning the intermediate transfer member.

The cleaning of the intermediate transfer member is a method of cleaning the intermediate transfer member by electrostatically transferring the untransferred developer to the photosensitive drum 1 as shown in FIG.

In the image forming apparatus of FIG. 1, the developer is primarily transferred from the photosensitive drum 1 to the intermediate transfer member 20, and at the same time, the developer remaining on the intermediate transfer belt 20 generated in the previous image forming step is removed. It may be returned to the photosensitive drum 1 (hereinafter, referred to as a primary transfer simultaneous cleaning method). The primary transfer simultaneous cleaning method has an advantage that a throughput is not reduced because a cleaning step is not particularly required.

Further, as shown in FIG. 7, a transfer residual developer collecting member 8 may be provided. The transfer residual developer collecting member 8 also
Various forms, such as a metal roll, a conductive elastic roll, a conductive fur brush, and a conductive blade, can be used. 27 is a bias power supply.

A voltage having a polarity opposite to that of the voltage applied to the cleaning charging member 7 is applied to the transfer residual developer collecting member 8, so that the transfer residual developer can be electrostatically cleaned.

In the apparatus shown in FIG. 7, for example, when the power is turned on, a bias having a polarity opposite to that of the photosensitive drum 1 is applied to the transfer residual developer collection member 8 to transfer the transfer residual developer in the transfer residual developer collection container 9. It is also conceivable to charge the developer and collect it in the cleaning device 13 for the photosensitive drum. This method has an advantage that the transfer residual developer collecting container 9 can be downsized.

While the belt-shaped intermediate transfer member has been described above, the intermediate transfer member of the present invention may be formed in a drum shape as shown in FIG.

As an evaluation, good electrostatic transfer can be performed from the initial stage, and a good image free of transfer failure and image deletion due to toner contamination on the surface layer of the belt can be obtained even after running for 60,000 full-color images. did it. Tables 1 and 2 show the structure and results of the intermediate transfer member of this example.

The image forming conditions of this embodiment will be described below.

Non-image area surface potential: -550 V Image area surface potential: -150 V Color developer (for all four colors): non-magnetic one-component toner Primary transfer voltage: +500 V Secondary transfer voltage: +1500 V Process speed: 120 mm / sec Development Bias: Vdc = -400V Vac = 1600Vpp Frequency 1800Hz

(Examples 2 and 3) In Examples 2 and 3,
An intermediate transfer belt was prepared and image evaluation was performed in the same manner as in Example 1 except that the conditions shown in Table 1 were changed. Table 2 shows the results.

(Example 4) A diameter of 182 mm and a length of 320
A rubber roller having an elastic layer was obtained by transfer molding and vulcanizing the elastic layer compound of Example 1 on the surface of an aluminum cylindrical roller having a thickness of 5 mm and a thickness of 5 mm using a mold. Next, an intermediate layer and a silica coating layer were obtained thereon by spray coating in the same manner as in Example 1 to obtain an intermediate transfer member having a three-layer structure. The resistance value of the intermediate transfer member was measured by the same method as in Example 1 and found to be 1.5 × 10 ¹⁰ Ω.

This intermediate transfer member was mounted on the full-color electrophotographic apparatus shown in FIG. 1, the intermediate transfer belt was changed to an intermediate transfer drum, and an OPC photosensitive drum was used as a photosensitive member.
The durability was evaluated in the same manner as in Example 1. Table 2 shows the results.

(Comparative Example 1) The procedure of Example 1 was repeated, except that only the intermediate layer was used, and the durability was evaluated. Table 2 shows the results.

Comparative Example 2 In the composition of the intermediate layer of Example 1, 4 parts of conductive carbon and 70 parts of silicone resin particles (average particle size: 1.5 μm) were added instead of conductive tin oxide, and dispersed and mixed. Paint (2). This was spray-coated on the elastic layer to obtain an intermediate transfer belt, and the durability was evaluated in the same manner as in Example 1. Tables 1 and 2 show the configuration and results.
Shown in

[0107]

[Table 1]

[0108]

[Table 2]

The secondary transfer efficiency in Table 2 was determined according to the following equation by measuring the reflection density on the intermediate transfer body and the reflection density on paper after the secondary transfer on the intermediate transfer body for cyan.

Secondary transfer efficiency (%) = (reflection density on paper)
/ (Reflection density on paper + reflection density on intermediate transfer body after secondary transfer) × 100

Further, the surface condition of the intermediate transfer member was observed visually and by a microscope after the endurance. The image was judged from the transferred image after durability.

[0112]

According to the present invention, since the intermediate transfer member has a silica coating layer, toner contamination and filming do not occur even under severe durability of repeated use, and the same transfer efficiency as in the initial stage. And it is possible to provide an excellent image forming apparatus in which surface cracks and cracks are not generated by repeated use.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of an image forming apparatus using an intermediate transfer belt as an intermediate transfer member.

FIG. 2 is a schematic configuration diagram illustrating an entire intermediate transfer belt.

FIG. 3 is a schematic configuration diagram illustrating a part of an intermediate transfer belt having two intermediate layers.

FIG. 4 is a schematic configuration diagram illustrating a part of an intermediate transfer belt having a belt reinforcing layer.

FIG. 5 is a schematic configuration diagram showing the entire intermediate transfer drum.

FIG. 6 is a schematic configuration diagram illustrating a cross section of an intermediate transfer drum.

FIG. 7 is a schematic view of an example of another image forming apparatus using an intermediate transfer belt as an intermediate transfer member.

FIG. 8 is a schematic diagram showing the absorbance of infrared absorption measurement.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 photoreceptor drum 2 primary charger 3 image exposure means 7 cleaning charging member 8 transfer residual development and development recovery member 9 transfer residual development and development recovery container 10 transfer guide 11 paper feed roller 13 cleaning means 15 fixing means 20 intermediate transfer belt 26 27, 28, 29 Bias power supply 41 Yellow toner 42 Magenta toner 43 Cyan toner 44 Black toner 62 Primary transfer roller 63 Secondary transfer roller 64 Secondary transfer facing roller 65, 66 Supporting roller 100 Support 101 Elastic layer 102 Intermediate layer 103 Silica Coating layer 104 Belt reinforcement layer P Transfer material

Claims (5)

[Claims] 1. An image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and further transferring the image onto a second image carrier, wherein the intermediate transfer member is coated with silica. An image forming apparatus comprising a layer. 2. The image forming apparatus according to claim 1, wherein said silica coating layer is the outermost layer of an intermediate transfer member. 3. The image forming apparatus according to claim 1, wherein the silica coating layer is obtained by applying and curing a paint containing at least polysilazane. 4. The SiO / S of the silica coating layer
The image forming apparatus according to claim 1, wherein the iN ratio is 1.1 or more. 5. The image forming apparatus according to claim 3, wherein said polysilazane is a modified polysilazane.