JP3472124B2 - Image forming apparatus and intermediate transfer belt - Google Patents

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 and an intermediate transfer member using an electrophotographic method, and in particular, a toner image formed on a first image carrier is once transferred to the intermediate transfer member ( The present invention relates to an image forming apparatus and an intermediate transfer member that obtain an image by further transferring (secondary transfer) onto a second image image carrier after the primary transfer).

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member transfers an image from a first image bearing member onto a second image bearing member attached or adsorbed on a transfer drum ( Compared with Japanese Patent Laid-Open No. 63-301960), processing and control (for example, gripping by a gripper, adsorbing and giving a curvature) are not required for the transfer material which is the second image carrier. Therefore, from thin paper (40 g / m ² paper) to thick paper (20
Up to 0 g / m ² paper), regardless of width or width.
There is an advantage that a wide variety of second image carriers can be selected.

Due to these advantages, color copiers and color printers using an intermediate transfer body are already in operation in the market.

[0004]

[Problems to be Solved by the Invention] However, recently, due to environmental problems and computer networking, the load on the printer is increasing more and more, and the demand for higher speed and higher durability of the printer is increasing. . In such a situation, when a conventional intermediate transfer belt made of resin or rubber is stretched with an arbitrary tension and repeatedly used, current may leak at the end portion and an image defect may occur. It was

To further explain this point, the photosensitive drum is
First, in the rotation process, it is necessary to uniformly charge the primary charger to a predetermined polarity and potential. Therefore, as the primary charger, a contact type charging member or an inner roller type is mainly used at present, but this type of charger has a gap between the charger and the photoconductor. Therefore, if the photoconductor has a part with a thin film thickness, the resistance of that part is low and the discharge is likely to concentrate, resulting in deterioration of the surface of the photoconductor. , Local shaving occurs.

In particular, this phenomenon is likely to occur in the non-image area portion at the edge of the photoconductor. This is because the photoconductor is mainly produced by a coating method called dipping, and it is because the film thickness at the beginning of coating on one side of the photoconductor becomes thin. Furthermore, when the printer speed is increased, the amount of current flowing through the primary charger is required to be increased accordingly, which promotes the above phenomenon.

[0007] On the other hand, the intermediate transfer belt is designed by laminating a resin or a rubber material so as to exhibit the required characteristics, and usually has a low resistance from the viewpoint of ensuring uniform conductivity and preventing leakage. On the conductive elastic layer, the outermost layer having a higher resistance than the elastic layer is provided. However, due to the speedup of the printer and the long-term use, the edge of the intermediate transfer belt (non-image area) is
If a crack occurs in the outermost layer having high resistance and peeling from the elastic layer occurs, this may serve as a starting point, and the defect may further spread to the internal image forming area.

In particular, an image forming apparatus using an intermediate transfer belt is often provided with some position detecting means on the belt in order to prevent overlay misregistration (color misregistration) of the respective component color images. There is a method to detect the position with an optical sensor by making a hole in the non-image forming area of the belt and transmitting light therethrough.However, this reduces the strength around the holed part, resulting in long-term use. Caused cracks in the outermost layer there, peeling from the elastic layer, etc.,
There is a risk of exposing the low resistance conductive elastic layer.

When the position where the outermost layer at the end portion of the belt is cracked or peeled off and the position where the local abrasion (non-image forming area portion) of the photoconductor is generated, the intermediate transfer belt of the intermediate transfer belt is detected. Excessive current flows from the elastic layer. As a result, the voltage applied to the intermediate transfer belt drops, so that a portion that is not sufficiently transferred is formed over the entire contact area of the intermediate transfer belt in the longitudinal direction of the photoconductor, resulting in a defective image. Furthermore,
Excessive current to the back electrode of the photoconductor may cause malfunction or damage of the electric control system of the electrophotographic apparatus.

An object of the present invention is to provide an image forming apparatus capable of obtaining a good image by using an intermediate transfer belt which can solve the above problems. That is,
The image forming apparatus of the present invention does not cause damage to the intermediate transfer belt (peeling from the outermost elastic layer or cracking) even after repeated use over a long period of time, and also causes a leak due to these. As a result, no image defect occurs.

[0011]

That is, according to the present invention, the first image carrier and the toner image formed on the first image carrier are primarily transferred, and the transferred toner image is transferred to the first image carrier. Two
Of an image forming apparatus having an intermediate transfer belt for transferring the secondary to the image bearing member, the intermediate transfer belt non-image forming region, ¹⁰ 10 Ω · cm or more volume resistivity, 0.5 k
Adhesive strength of g to 5 kg and 100 % to 1000
% Have a tape having the elongation at break, contact of the tape
Adhesion strength Y (kg) and maximum of the surface layer of the intermediate transfer belt
The image forming apparatus is characterized in that the relationship of the stress Z (kg) of the tape with respect to elongation satisfies the following expression Y ≧ 0.5 + Z / 5 .

The present invention is also an intermediate transfer belt used in the image forming apparatus.

The reinforcing effect can be expected by providing the tape at the end portion which is the non-image forming area of the intermediate transfer belt made of resin or rubber, or the opening portion formed at the end portion. However, when the present inventors prototyped and studied intermediate transfer belts in which various kinds of tapes were adhered to the non-image area, depending on the characteristics of the tapes, satisfactory results may not be obtained. there were. Therefore, as a result of diligent studies on this point, the present inventors have found that the resistance, adhesive strength, and elongation at break of the tape are important factors, and have specified this point as described above.

That is, the volume resistance of the tape is 10 ¹⁰ Ω · c
By setting the adhesive strength to m or more, the adhesive strength to 0.5 kg or more, and the breaking elongation to 5%, the mechanical strength, durability, and pressure resistance of the intermediate transfer belt can be improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a tape base material is adhered to a preferably toner image carrying surface of an intermediate transfer belt via an adhesive, or is welded without using the adhesive.

The tape in the present invention means the tape base material and the adhesive where the adhesive is used, and the tape base when the adhesive is not used.

When the tape is adhered or welded,
It is a non-image forming area where an image is not formed, such as an edge portion.
The area covered by the tape may be the entire edge or a part of it,
If there is an opening at the end, it is preferable that the tape covers at least the opening.

The volume resistivity of the tape is 10 ¹⁰ Ω · cm or more, preferably 10 ¹² Ω · cm or more. 10 ¹⁰ Ω
This is because if it is less than cm, the pressure resistance becomes insufficient. From this point of view, in the present invention, the higher the volume resistance value of the tape, the more preferable, but the limit of highly accurate measurement is about 10 ¹⁷ Ω · cm.

The volume resistance value of the tape in the present invention is a value measured by using a resistance measuring device (HIRESTA: resistance measuring device manufactured by Mitsubishi Yuka: value after 5 seconds after application of 100V).

The adhesive strength (if an adhesive is used, between the intermediate transfer member and the adhesive, or between the adhesive and the substrate, whichever is smaller) is 0.5 kg or more, preferably 0.75 k.
g or more. This is because if it is less than 0.5 kg, the adhesiveness will be insufficient and it may peel off during use. From this viewpoint, in the present invention, the larger the adhesive strength, the more preferable, but from the viewpoint of productivity and heat resistance of the material, 5 kg or less is preferable.

The adhesive strength is a value measured based on the following.

(1) The intermediate transfer belt is cut into a width of 25 mm and a length of 100 mm.

(2) The above belt sample has a width of 25 mm,
A tape cut into a length of 200 mm is adhered under the same conditions as in actual use, with one end in the length direction aligned.

(3) The play portion of the tape is folded back 180 ° in the opposite direction, and a tensile tester (TENSILON RT) is used.
C-1250A, made by ORIENTEC), hold the belt at the bottom and the tape between the top, 50mm / min.
Peel off at the speed of. And after I started to peel it off,
The average value of the force from the time of peeling 20 mm to 80 mm is obtained.

The breaking elongation is 5% or more, preferably 10% or more, more preferably 100% or more. This is because if it is less than 5%, the belt cannot follow the elongation when stretched with an arbitrary tension, resulting in peeling or breakage. From this point of view, in the present invention, the larger the elongation at break, the more preferable, but it is preferably 1000% or less from the viewpoint that the tape tends to sag due to excessive elongation.

The breaking elongation is a value measured according to ASTM D638.

As the base material of the tape of the present invention, for example,
Ethylene propylene rubber (EPDM), nitrile rubber (NBR), styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), acrylic rubber (ACM), silicone rubber, fluororubber, etc. Rubber materials such as polystyrene, polystyrene, polyvinyl chloride, polyurethane, polyamide, polyamide thermoplastic elastomers, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer. Polymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acrylic acid Butyl Polymer, styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methacrylic acid copolymer, styrene-ethyl methacrylate copolymer, styrene- Phenyl methacrylate, etc.), styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, etc., styrene-based resins (styrene or styrene-substituted homopolymer or copolymer) ), Methyl methacrylate resin, butyl methacrylate resin, ethyl acrylate resin, butyl acrylate resin, modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin, acrylic urethane resin, etc.), vinyl chloride resin, Styrene vinyl acetate copolymer, salt Vinyl -
Vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resin, polyurethane resin, silicone resin, fluorine resin, ketone resin, A resin sheet such as an ethylene-ethyl acrylate copolymer, a xylene resin, a polyvinyl butyral resin, a polyamide resin, or a modified polyphenylene oxide resin can be used.

As the adhesive, for example, thermosetting resin type (epoxy resin type, phenol resin type), thermoplastic resin type (polyvinyl acetate type, polyamide type), rubber type (silicon rubber type, polyurethane rubber type) , Solution type such as complex type (rubber / phenol type, epoxy / nylon type), emulsion type, pressure sensitive type, rewet type, polycondensation type, film type,
A hot-melt material can be appropriately selected and used in consideration of the adhesive strength between the intermediate transfer belt and the substrate.

The method of attaching the tape to the intermediate transfer belt is not particularly limited, but for example, a cylindrical mold or the like is covered with the intermediate transfer belt, and a liquid adhesive is applied onto the base. The material may be pressed, or a film adhesive may be sandwiched between the base material and the intermediate transfer belt, and may be attached under predetermined adhesion conditions.

As an adhesion method which does not use an adhesive, for example, there are the following methods.

(1) Either the tape or the intermediate transfer belt surface layer is melted and adhered.

(2) Both the tape and the surface layer of the intermediate transfer belt are melted and adhered.

Means for melting the material include applying a good solvent, heating with a sealer, an ultrasonic welder or the like to a temperature above the softening point temperature, whereby one of the tape and the intermediate transfer belt surface layer, or Melt both and stick together.

If more adhesiveness is required,
For the tape base material, it is preferable to select the same material as the resin used for the surface layer of the intermediate transfer belt.

The material of the same quality means that they are the same system in terms of classification of resin and rubber. As the resin type, urethane type, epoxy resin type, silicon resin type, unsaturated polyester type, fluororesin type, polyamide type, polyethylene type, polypropylene type, vinyl chloride type, vinylidene chloride type, polystyrene type, methacrylic type resin, polycarbonate Examples thereof include a system and a polyacetal type. For example, in the case of a urethane type, it can be regarded as the same quality if it has a urethane bond, which is a characteristic of a urethane type, in the molecule.
Further, as the rubber type, urethane rubber type, styrene-butadiene rubber type, high styrene rubber type, butadiene rubber type, isoprene rubber type, ethylene-propylene copolymer type, nitrile butadiene rubber type, chloroprene rubber type,
Examples thereof include butyl rubber-based, silicone rubber-based, fluororubber-based, nitrile rubber-based, acrylic rubber-based, epichlorohydrin rubber-based, norbornene rubber-based and the like. in this way,
As long as they are of the same system in terms of classification of resin and rubber, they can be regarded as materials of the same quality.

The method of attaching the tape to the intermediate transfer belt is not particularly limited, but, for example, a sealer, a welder or the like is used, and the intermediate transfer belt is covered with a cylindrical mold or the like. Put the tape on top and weld under the specified conditions.

As described above, a liquid adhesive, an adhesive system using a hot melt adhesive, a welding system not using an adhesive,
Either can be bonded.

However, when higher durability is required, the welding system is preferable to the adhesive system. The reason for this is that in an adhesive system, the tape is damaged by interfacial destruction between the belt surface layer / adhesive layer, adhesive layer / tape due to deterioration of the adhesive layer, cohesive failure of the adhesive layer, etc. This is because the tape and the surface layer are integrated with each other or adhered with higher strength in the welding system, so that the risk of peeling is extremely small.

The thickness of the tape is arbitrary, but a preferable range is 10 to 1000 μm. When the thickness of the tape is less than 10 μm, the reinforcing effect and the effect of improving the pressure resistance tend to be small, and when the thickness is more than 1000 μm, the tape sticking portion (non-image area) and non-sticking portion (image area) The step between and tends to be large.

As described above, when an opening for the purpose of position detection using an optical sensor is provided at the end of the intermediate transfer belt 20 and the opening 53 is covered with the tape 50 (FIG. 7),
The tape 50 needs to be light transmissive at the wavelength used so that the sensor operates normally.

Specifically, at 700-1500 nm,
The transmittance of light having any wavelength is preferably 10% or more, and particularly preferably 20% or more. This is because if it is less than 10%, the sensor does not operate normally and stable and accurate position detection is difficult.
It should be noted that the transmittance of light having any one of the wavelengths of 700 to 1500 nm is 10% or more in some cases, as shown in FIG. However, it means that it is necessary that the transmittance is 10% or more at any wavelength, and by using the detection means using infrared light having a dominant wavelength in that wavelength range, stable In addition, accurate position detection is possible.

The transmittance was measured using a U-3400 large sample chamber integrating sphere accessory manufactured by Hitachi Ltd.

In the present invention, the adhesive strength Y
(Kg / 25 mm width) and the stress Z (kg) at the maximum elongation of the surface layer of the intermediate transfer belt preferably satisfy the following formula.

Y ≧ 0.5 + Z / 5 When the elongation stress of the tape is large, when the intermediate transfer belt is stretched by stretching the intermediate transfer belt with an arbitrary tension, the load between the tape and the belt surface layer is large, so that it can withstand long-term use. To get
Therefore, stronger adhesion is required. As a result of intensive studies by the inventors, it was found that the above relationship is established between the adhesive strength of the intermediate transfer belt and the stress at the maximum elongation of the surface layer of the intermediate transfer belt.

The maximum elongation is in a model in which the intermediate transfer belt is used. For example, the intermediate transfer belt is usually tensioned by several rollers, but the elongation of the surface layer of the intermediate transfer belt reaches the maximum at the contact point (apex) with the roller having the smallest diameter (large curvature). .

The elongation stress was defined as the stress at the maximum elongation of the surface layer of the intermediate transfer belt under the conditions of a tensile tester, a dumbbell No. 3 test piece, and a pulling speed of 50 mm / min and a distance between initial marked lines of 30 mm.

FIG. 9 is a graph showing the relationship between the adhesive strength Y and the stress Z based on the results of Examples described later. Thus, the above equation and the obtained result are in good agreement.

The method for achieving each physical property of the present invention is not particularly limited, and the material of the tape base material and the adhesive, the bonding method, the thickness of the tape, the material of the surface layer of the intermediate transfer belt, etc. Should be selected appropriately.

The intermediate transfer belt of the present invention may be a single layer or may be, for example, a laminate having a base layer and a surface layer. In the present invention, a laminated structure is preferable in that the functions of the layers can be separated.

As the rubber, elastomer and resin used for the base layer and surface layer of the intermediate transfer belt used in the present invention,
For example, as rubber and elastomer, natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene terpolymer, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylonitrile butadiene rubber, Urethane rubber, syndiotactic 1,2-polybutadiene, epichlorohydrin rubber, acrylic rubber, silicone rubber, fluororubber, polysulfide rubber, polynorbornene rubber, hydrogenated nitrile rubber and thermoplastic elastomer (for example, polystyrene type, polyolefin type, Polyvinyl chloride type, polyurethane type,
One type or two or more types selected from the group consisting of polyamide type, polyester type and fluororesin type) can be used. However, the material is not limited to the above materials.

As the resin, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-
Butadiene copolymer, styrene-vinyl chloride copolymer,
Styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer) Polymer, styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer and styrene) -Phenyl methacrylate copolymer etc.),
Styrene resins such as styrene-α-chloroacrylic acid methyl copolymer and styrene-acrylonitrile-acrylic acid ester copolymer (styrene or a styrene-substituted homopolymer or copolymer), methyl methacrylate resin, methacrylic acid Butyl acrylate resin, ethyl acrylate resin, butyl acrylate resin, modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin and acrylic urethane resin, etc.), vinyl chloride resin,
Styrene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resin,
Use one or more selected from the group consisting of polyurethane resin, silicone resin, fluororesin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, polyamide resin and modified polyphenylene oxide resin. be able to. However, the material is not limited to the above materials.

A conductive agent may be added to adjust the resistance value of the intermediate transfer belt used in the present invention. The conductive agent is not particularly limited, but examples thereof include carbon, metal powders such as aluminum and nickel, metal oxides such as titanium oxide, quaternary ammonium salt-containing polymethylmethacrylate, polyvinylaniline, polyvinylpyrrole, polydiene. One kind or two or more kinds selected from the group consisting of conductive polymer compounds such as acetylene, polyethyleneimine, boron-containing polymer compounds and polypyrrole can be used. However, the conductive agent is not limited to the above.

As a method of mixing and dispersing various additives in the binder such as various resins and elastomer rubbers, known methods can be appropriately used. When the binder component is rubber or elastomer, a device such as a roll mill, a kneader and a Banbury mixer is used, and when it is liquid, it can be dispersed by using a ball mill, a bead mill, a homogenizer, a paint shaker, a nanomizer or the like.

As a method of providing the surface layer on the base layer of the intermediate transfer belt, coating of a paint, for example, dipping method,
There are roll coating method, spray coating method, brush coating method, adhesion of resin film and the like, but not limited thereto.

The surface layer provided on the base layer of the intermediate transfer belt may be one layer, but may be two or more layers in some cases.

The intermediate transfer belt used in the present invention preferably has a core layer. This improves the mechanical strength of the intermediate transfer belt and eliminates any image defects due to permanent elongation.

The role of the core layer in the present invention is to improve the mechanical strength of the intermediate transfer belt. As a concrete form example of the core layer, as shown by 23 in FIGS. 2 to 4, a woven cloth shape, a non-woven cloth shape, a thread shape, a film shape and the like can be considered. That is, the core layer does not necessarily have to be a continuous layer having no gap. Therefore, the core layer may have gaps or irregularities. In addition, 21 is a base layer and 24 is a coating layer.

The material forming the core layer is, for example, cotton,
Natural fibers such as silk, hemp and wool, regenerated fibers such as chitin fibers, alginic acid fibers and regenerated cellulose fibers, semi-synthetic fibers such as acetate fibers, polyester fibers, nylon fibers, acrylic fibers, polyolefin fibers, polyvinyl alcohol fibers, polychlorinated Synthetic fibers such as vinyl fibers, polyvinylidene chloride fibers, polyurethane fibers, polyalkylparaoxybenzoate fibers, polyacetal fibers, aramid fibers, polyfluoroethylene fibers, phenol fibers, inorganic fibers such as carbon fibers, glass fibers, boron fibers, iron fibers ,
From the group consisting of metal fibers such as copper fibers, one kind or two or more kinds can be selected and used. Of course, the material used for the core layer in the present invention is not limited to the above materials.

From the viewpoint of easiness of production and production cost, a preferable example of the form of the core layer is a woven fabric or a yarn as shown in FIGS. 2 and 3. The yarn may be a single filament or a plurality of twisted filaments, and may be any twisted method such as a single twisted yarn, a plied yarn, and a twin yarn. Further, for example, fibers of the materials shown in the above material group may be mixed and spun. Further, in some cases, the yarn may be subjected to an appropriate conductive treatment before use.

Similarly, the woven fabric is, for example, a knitted fabric,
Any woven fabric can be used, and of course, a mixed woven fabric can also be used. Also, in some cases,
The woven fabric may be used after being subjected to an appropriate conductive treatment.

The method for producing the core layer is not particularly limited, but for example, a method in which a woven fabric woven in a tubular shape is covered with a mold and a coating layer is provided thereon, or a tubular woven material is woven. Examples include a method in which a woven cloth is dipped in liquid rubber or the like to form a coating layer on one or both sides of the core layer, a method in which threads are spirally wound around a mold or the like at an arbitrary pitch, and a coating layer is formed thereon. To be In this case, the base layer is a combination of the core layer and the coating layer.

As described above, the purpose of providing the core layer on the intermediate transfer belt used in the image forming apparatus of the present invention is to reinforce the intermediate transfer belt. Therefore, the thickness of the core layer is arbitrary, but a preferable range is 10 to 500 μm.
When the thickness of the core layer is less than 10 μm, the reinforcing effect tends to be small. On the other hand, when the thickness is more than 500 μm, the rigidity of the core layer is excessively increased, and it becomes difficult to smoothly drive the intermediate transfer belt.

The thickness of the core layer in the present invention means
When the core layer is a woven or non-woven fabric, the woven or non-woven fabric in the state before being molded into the intermediate transfer belt,
It is a value measured by a thickness measuring machine TH-102 (manufactured by Tester Sangyo Co., Ltd.).

When the core layer is in the form of threads, the thickness of the thread is the thickness of the core layer. Regarding the thickness of the yarn, the yarn in the state before being formed into the intermediate transfer belt is measured by the above thickness measuring machine.

Further, when the core layer is in the form of a film, the value of the thickness of the film measured by the above thickness measuring machine is taken as the thickness of the core layer. However, if it is impossible to measure with a thickness measuring machine, cut the intermediate transfer belt in the thickness direction,
The value observed with a microscope is the thickness of the core layer.

When the form of the core layer does not correspond to any of the above, the intermediate transfer belt is cut in the thickness direction,
The value observed with a microscope is the thickness of the core layer.

The coating layer provided on the core layer may be one layer, but may be two or more layers in some cases. In particular, when a coating layer (elastic layer) made of an elastic material such as rubber or elastomer is provided on the upper layer of the core layer, and a coating layer (outermost layer) made of resin or the like having excellent releasability is provided thereon, The elastic layer ensures a uniform and sufficient nip portion for primary transfer and secondary transfer, and the outermost layer
Such a treatment is preferable because the transfer efficiency (particularly, the secondary transfer efficiency) is improved.

The sum of the thicknesses of the coating layers provided on the core layer may be at least the thickness of the core layer, which is the basis of the present invention. Since it is difficult to smoothly drive the intermediate transfer belt, it is not preferable. Therefore, the sum of the thicknesses of the coating layers provided on the core layer is preferably 10 μm to 1500 μm.

The thickness of the intermediate transfer belt is preferably thin in terms of driving the belt smoothly, and is preferably thick in terms of not impairing the mechanical strength and flexibility of the belt. Specifically, it is preferably 0.1 to 2 mm. Further, when the coating layer provided on the core layer is provided, the thickness of the outermost layer is preferably as thin as possible so as not to impair the flexibility of the coating layer thereunder, specifically 1 to
The thickness is more preferably 500 μm, and further preferably 5 to 200 μm.

The thickness of these various layers can be measured in the same manner as the core layer.

Further, in the present invention, if the resistance value of the intermediate transfer belt is too high, the first transfer of the developers of the second and subsequent colors may result in the first transfer of the first developer being completed. It is easy to return to the image carrier of No. 1 and it becomes difficult to obtain an image with the desired color tone.

If the resistance value of the intermediate transfer belt is too low, the resistance value of the intermediate transfer belt tends to have a large difference between the portion that has undergone the primary transfer and the portion that has not. As a result, the second and subsequent color developers cannot be efficiently transferred, and it becomes difficult to obtain an image with the desired color tone. Therefore, the range of the resistance value of the intermediate transfer belt is 1 × 10 ⁴ Ω or more and 1 ×
It is preferably 10 ¹¹ Ω or less.

<Measurement Method of Resistance Value of Intermediate Transfer Belt> (1) As shown in FIG. 5, the intermediate transfer belt is stretched by the rollers 200 and 201, and the intermediate transfer belt is further divided into two metal rollers 202 and Sandwiched with 203, DC power supply 20
4. Resistor 205 with proper resistance value, potentiometer 206
Connect. (2) The driving roller 200 drives the intermediate transfer belt so that the moving speed of the surface of the intermediate transfer belt becomes 100 to 300 mm / sec. (3) +1 kV is applied to the circuit from a DC power source, and the potential difference V _r across the resistor is read by a potentiometer. The atmosphere at the time of measurement is 23 ± 5 ° C. and 50 ± 10% RH. (4) The current value I flowing in the circuit is obtained from the obtained potential difference V _r . (5) Resistance value of intermediate transfer belt = applied voltage (1 kV) /
The current value I.

As the first image carrier, at least the outermost layer is made of polytetrafluoroethylene (PTFE).
Higher than 1 using a photosensitive drum containing fine powder of
Such a treatment is preferable because the secondary transfer efficiency can be obtained. This is because by containing the fine powder of PTFE,
It is considered that this is because the surface energy of the outermost layer of the photosensitive drum 1 is lowered and the releasability of the toner is improved.

FIG. 1 shows an example of a schematic configuration of a color image forming apparatus (copier or laser beam printer) of the present invention utilizing an electrophotographic process.

Reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as a first image bearing member, which is rotationally driven at a predetermined peripheral speed (process speed) in the direction of the arrow.

While the photosensitive drum 1 is rotating, the primary charger 2
Is uniformly charged to a predetermined polarity and potential by means of an image exposing means 3 (not shown, color separation / imaging exposure optical system of a color original image, modulation corresponding to a time series electric digital image signal of image information). Exposure 3 by a scanning exposure system by a laser scanner that outputs the generated laser beam.
In this way, an electrostatic latent image corresponding to the first color component image (for example, yellow color component image) of the target color image is formed.

Next, the electrostatic latent image is developed by the first developing device (yellow developing device 41) with the yellow toner Y which is the first color. At this time, the developing units of the second to fourth developing units (magenta color developing unit 42, cyan color developing unit 43, black color developing unit 44) are not operating and do not act on the photosensitive drum 1. The first color yellow toner image is not affected by the second to fourth developing devices.

The intermediate transfer belt 20 is rotationally driven in the direction of the arrow at a predetermined peripheral speed.

The above-mentioned first formed and carried on the photosensitive drum 1.
By the electric field formed by the primary transfer bias applied from the primary transfer roller 62 to the intermediate transfer body 20 while the yellow toner image of the color passes through the nip portion between the photosensitive drum 1 and the intermediate transfer belt 20, Intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 20.

The surface of the photosensitive drum 1 on which the transfer of the yellow toner image of the first color has been completed is cleaned by the cleaning device 13.

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 successively transferred onto the intermediate transfer member 20 in a superimposed manner to form a desired full-color image. To be done.

Reference numeral 63 denotes a secondary transfer roller, which corresponds to the secondary transfer counter roller 64 and is supported in parallel to the lower surface of the intermediate transfer member 20 so as to be separated therefrom.

The primary transfer bias for the sequential superposition transfer of the toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer belt 20 has a polarity opposite to that of the toner, and the bias power source 2
9 is applied. The applied voltage is, for example, + 100V
Is in the range of ˜2 kV.

In the primary transfer step, the secondary transfer roller 63 and the charging member 7 for cleaning are used as the intermediate transfer belt 2.
Keep it away from zero.

The transfer of the full-color image formed on the intermediate transfer belt 20 onto the transfer material P which is the second image carrier is performed while the secondary transfer roller 63 is brought into contact with the intermediate transfer belt 20 and is fed. The transfer material P is fed from the roller 11 to the contact nip between the intermediate transfer body 20 and the secondary transfer roller 63 at a predetermined timing, and the secondary transfer bias is applied to the bias power source 2.
8 is applied to the secondary transfer roller 63. The transfer material P on which the toner image is transferred is fixed by the fixing device 1.
Then, it is heated and fixed.

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

The transfer residual toner is electrostatically transferred to the photosensitive drum 1 at and near the nip portion with the photosensitive drum 1, so that the intermediate transfer belt 20 is cleaned.

For cleaning the intermediate transfer belt, any cleaning device such as blade cleaning, fur brush cleaning, electrostatic cleaning, or a combination thereof can be used, but from the viewpoint of downsizing and cost reduction of the device. Therefore, as a preferable cleaning method, for example, as shown in FIG. 1, a method of cleaning the intermediate transfer belt by electrostatically transferring the transfer residual toner to the photosensitive drum 1 can be mentioned. Figure 1
In the above, the cleaning charging member 7 is a metal roll,
Various forms such as an elastic roll having conductivity, a fur brush having conductivity, and a blade having conductivity can be adopted.

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

Further, as shown in FIG. 6, a transfer residual toner collecting member 8 may be provided. This transfer residual toner collecting member 8
Also, various forms such as a metal roll, an elastic roll having conductivity, a fur brush having conductivity, and a blade having conductivity can be adopted. Here, the transfer residual toner can be electrostatically cleaned by applying a voltage having a polarity opposite to that of the voltage applied to the cleaning charging member 7 to the transfer residual toner collecting member 8.

In the apparatus shown in FIG. 6, for example, when the power is turned on, a bias having a reverse polarity to that of the photosensitive drum 1 is applied to the transfer residual toner recovery member 8 to transfer the residual transfer developer recovery container 9
It is also possible to charge the transfer residual toner in the inside and collect it in the cleaning device 13 of the photosensitive drum. This method
This has an advantage that the transfer residual toner collecting container 9 can be downsized.

[0093]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 A rubber compound having the following composition was uniformly wound around a cylindrical mold with a thickness of 0.4 mm. Next, a nylon system (diameter 10
0 μm) was spirally wound on the compound at a pitch of 1 mm. A rubber compound having the following composition extruded into a tube shape is covered thereon, and vulcanized and polished to give a thickness of 0.3 m on the core layer.
A rubber belt (base layer) containing a core layer having a thickness of 0.8 mm, which has an elastic layer of m and an elastic layer having a thickness of 0.4 mm under the core layer, was obtained.

<Rubber compounding (parts by weight)> SBR rubber 30 parts EPDM rubber 70 parts Vulcanizing agent (precipitated sulfur) 1.5 parts Vulcanization aid (zinc white) 2 parts Vulcanization accelerator (MBT) 1.5 parts Vulcanization accelerator (TMTM) 1.2 parts Conductive agent (carbon black) 25 parts Dispersion aid (stearic acid) 1 part Plasticizer (naphthenic process oil) 40 parts

Next, a paint for obtaining a coating layer (surface layer) of one layer was prepared on the belt in the following formulation.

<Paint formulation (parts by weight)> Polyurethane prepolymer 100 parts Fine PTFE resin powder 70 parts Methyl ethyl ketone 400 parts 50 parts of N-methylpyrrolidone

Spray coating the above paint onto the belt,
After being dried by touch at room temperature, the residual solvent was removed by heating at 120 ° C. for 2 hours to obtain an intermediate transfer belt having a coating layer (surface layer) having a thickness of 30 μm. The resistance value of the obtained intermediate transfer belt was 1 × 10 ⁶ Ω.

Further, 5 mm are provided at four non-image areas at the end of the belt.
Make a hole in the corner, and make a 15mm square in the opening, and a thickness of 100.
Ultrasonic welding machine (BRA)
NSON 900M series ultrasonic welder, manufactured by Nippon Emerson Co., Ltd., was used to adhere under welding energy of 100 J and pressure of 10 kg / cm ² . When the adhesive portion was confirmed, both the tape and the surface layer of the intermediate transfer belt were melted and integrated.

Base material Urethane resin (thickness 100 μm) Volume resistance 10 ¹² Ω · cm Adhesive strength 1.5 kg Breaking elongation 500% Light transmittance (960 nm) 90% Stress 0.2 kg

This intermediate transfer belt was adhered to the full-color electrophotographic apparatus shown in FIG. 1, and the temperature was 15 ° C. and the humidity was 10
In a low temperature and low humidity environment of 1%, continuous printing of 150,000 full-color images was performed. The results are shown in Table 1. The image forming conditions of this embodiment are shown below.

[0102]

Example 2 An intermediate transfer belt was prepared and evaluated in the same manner as in Example 1 except that the tape having the following constitution was used, and the results are shown in Table 1.

Base material Polyethylene terephthalate (PET) (thickness 25 μm) Volume resistance 10 ¹⁵ Ω · cm Adhesive strength 2.0 kg Tape breaking elongation 120% Light transmittance (960 nm) 95% Stress 1.7 kg

(Example 3) An intermediate transfer belt was prepared and evaluated in the same manner as in Example 1 except that the surface layer-soluble coating material had the following formulation. The results are shown in Table 1. The resistance value of the obtained intermediate transfer belt was 2 × 10 ⁶ Ω.

<Paint formulation (parts by weight)> Polyurethane prepolymer 100 parts Hardener (isocyanate) 4 parts Fine PTFE resin powder 70 parts Methyl ethyl ketone 400 parts 50 parts of N-methylpyrrolidone

(Example 4) Using a heat sealer (manufactured by Shinwa Machine Co., Ltd.), a tape having the following constitution was heated at a hot plate temperature of 110 ° C
An intermediate transfer belt was prepared and evaluated in the same manner as in Example 3 except that the affixing was performed under the adhesion conditions of a pressure of 3 kg / cm ² and a time of 20 seconds. The results are shown in Table 1.

Base material Fluororesin sheet (thickness 50 μm) Adhesive Acrylic thermal adhesive film (thickness 50 μm) Volume resistance 10 ¹⁵ Ω · cm Adhesive strength 1.5 kg Breaking elongation 300% Light transmittance (960 nm) 95% Stress 0.6kg

(Examples 5 to 13 ) An intermediate transfer belt was prepared and evaluated in the same manner as in Example 4 except that the tape had the structure shown in Table 1. The results are shown in Table 1.

Comparative Example 1 An intermediate transfer belt was prepared and evaluated in the same manner as in Example 1 except that the tape having the following constitution was used. The results are shown in Table 1.

Base material Lithium perchlorate-containing urethane resin (thickness 100 μm) Volume resistance 10 ⁹ Ω · cm Adhesive strength 2.5 kg Breaking elongation 500% Light transmittance 90% Stress 0.2 kg

Comparative Example 2 An intermediate transfer belt was prepared and evaluated in the same manner as in Example 4 except that the tape having the following constitution was used. The results are shown in Table 1.

Base material Urethane resin (thickness 100 μm) Adhesive Olefin-based thermal adhesive film (thickness 50 μm) Volume resistance 10 ¹² Ω · cm Adhesive strength 0.3 kg Breaking elongation 500% Light transmittance 90% Stress 0.2 kg

[0114]

[Table 1]

[0115]

As described above, according to the present invention, excellent mechanical strength, durability and pressure resistance can be obtained without causing damage to the end portion of the intermediate transfer belt even after repeated use over a long period of time. It was possible to provide an image forming apparatus having the above.

[Brief description of drawings]

FIG. 1 is a schematic view of a full-color image forming apparatus using an intermediate transfer belt of the present invention.

FIG. 2 is a schematic view of a partial layer structure of an intermediate transfer belt of the present invention having a woven cloth-like core layer.

FIG. 3 is a schematic view of a partial layer structure of the intermediate transfer belt of the present invention having a thread-shaped core layer.

FIG. 4 is a schematic view of a partial layer structure of an intermediate transfer belt of the present invention having a film-shaped core layer.

FIG. 5 is a schematic view of an intermediate transfer belt resistance measuring device of the present invention.

FIG. 6 is a schematic view of a full-color image forming apparatus using the intermediate transfer belt of the present invention.

FIG. 7 is a perspective view of an intermediate transfer belt having the tape of the present invention in an opening at the end.

FIG. 8 is a diagram showing an example of a light transmittance curve.

FIG. 9 is a graph showing the relationship between adhesive strength and stress in the present invention.

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Minoru Shimojo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (56) References JP-A-4-345457 (JP, A) JP-A-8-63000 (JP, A) JP-A-10-198179 (JP, A) Actual development 4-50872 (JP, A) U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/16 G03G 15/01

Claims (18)

(57) [Claims] 1. A first image carrier and a toner image formed on the first image carrier are primarily transferred, and the transferred toner image is secondarily transferred to a second image carrier. In the image forming apparatus having the intermediate transfer belt, the intermediate transfer belt is placed in the non-image forming area at 10 ¹⁰ Ω · c.
A tape having a volume resistance value of m or more, an adhesive strength of 0.5 kg or more and 5 kg or less, and a breaking elongation of 100% or more and 1000% or less, and an adhesive strength Y (kg) of the tape and an intermediate transfer belt An image forming apparatus characterized in that the relationship of the stress Z (kg) of the tape at the maximum elongation of the surface layer satisfies the following expression Y ≧ 0.5 + Z / 5. 2. The image forming apparatus according to claim 1, wherein the intermediate transfer belt has an opening in a non-image forming area, and the tape covers at least the opening. 3. The image forming apparatus according to claim 2, wherein the tape has a transmittance of 10% or more for light having a wavelength of 700 to 1500 nm. 4. The image forming apparatus according to claim 1, wherein the tape has a volume resistance value of 10 ¹² Ω · cm or more. 5. The image forming apparatus according to claim 1, wherein the tape has an adhesive strength of 0.75 kg or more. 6. The image forming apparatus according to claim 1, wherein the tape has a tape base material and an adhesive. 7. The image forming apparatus according to claim 1, wherein the tape is welded to the intermediate transfer belt. 8. The image forming apparatus according to any one of claims 1 to 7 wherein the intermediate transfer belt has a base layer and surface layer. 9. The image forming apparatus according to claim 1, wherein the first image carrier is an electrophotographic photosensitive member. 10. The toner image formed on the first image carrier is primarily transferred, and the transferred toner image is transferred to the second image.
In the intermediate transfer belt which is secondarily transferred onto the image carrier, the non-image forming area has a volume resistance value of 10 ¹⁰ Ω · cm or more, an adhesive strength of 0.5 kg or more and 5 kg or less, and 100%.
A tape having a breaking elongation not less than 1000% is used, and the relationship between the adhesive strength Y (kg) of the tape and the stress Z (kg) of the tape at the maximum elongation of the surface layer of the intermediate transfer belt is expressed by the following equation. An intermediate transfer belt characterized by satisfying Y ≧ 0.5 + Z / 5. 11. The intermediate transfer belt according to claim 10, wherein the intermediate transfer belt has an opening in a non-image forming area, and the tape covers at least the opening. 12. The intermediate transfer belt according to claim 11, wherein the tape has a transmittance of 10% or more with respect to light having a wavelength of 700 to 1500 nm. 13. The intermediate transfer belt according to claim 10, wherein the tape has a volume resistance value of 10 ¹² Ω · cm or more. 14. The intermediate transfer belt according to claim 10, wherein the tape has an adhesive strength of 0.75 kg or more. 15. The intermediate transfer belt according to claim 10, wherein the tape has a tape base material and an adhesive. 16. The intermediate transfer belt according to claim 10, wherein the tape is welded to the intermediate transfer belt. 17. The intermediate transfer belt according to claim 10, wherein the intermediate transfer belt has a base layer and a surface layer. 18. The intermediate transfer belt according to claim 10, wherein the first image bearing member is an electrophotographic photosensitive member.