JP2000356918A - Endless belt for electrophotographic recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the meandering movement of an endless belt in a belt type electrophotographic recorder. SOLUTION: This endless belt for an electrophotographic recorder is the endless belt A provided with a rib (a) at least on one side end, laid on a group of rolls 1 and 2 and tensioned by the tension roll 2 out of the rolls, and the meandering of the belt A is prevented by movably fitting the rib (a) in a roll groove (d) or a guide. Then, it is made of a resin film incorporating a solid lubricant by 0.5 to 5 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless belt for an electrophotographic recording apparatus, and is useful as an endless belt in a toner image fixing device, a toner image transfer device or an intermediate transfer device.

[0002]

2. Description of the Related Art An endless belt is sometimes incorporated in an electrophotographic recording apparatus such as a printer, a copying machine, a video printer, and a facsimile. For example, as a fixing device for fixing an unfixed toner image carried on a recording sheet to a recording sheet by applying heat and pressure, a fixing device shown in FIG.
Are known. In FIG. 4 (a), 1 'is a drive roll, 2' is a tension roll, and A 'is an endless belt suspended on these rolls. Reference numeral 3 'denotes a heater internally disposed on the endless belt A', and reference numeral 4 'denotes a pressure roller (following roll) externally disposed on the endless belt A' so as to face the heater 3 '. is there. 9 'is a recording paper, 9
0 'is an unfixed toner image. To fix the toner image by this fixing device, tension is applied to the endless belt A 'by the tension roll 2', the endless belt A 'is rotated by the drive roll 1', and the pressure roll is applied. Pass the recording paper 9 'between 4' and the endless belt A ',
The toner image 90 'is fixed on the recording paper 9' by heating by the heater 3 'and pressing by the pressing roll 4'.

In this fixing device, a tension roller is used.
Since both ends of the roll 2 'are supported so as to be movable in the direction perpendicular to the roll axis, the tension roll 2' is inclined due to the unbalanced tension state, and the endless belt A '
May move closer. Therefore, as shown in FIG. 4B, a rib a 'is formed on the inner surface of the width end of the endless belt A'.
It is proposed that the rib a 'be loosely fitted in the groove d' provided in the roll 1 '(2') to prevent the endless belt A 'from shifting.

[0004]

When the endless belt is shifted, the angle between the axial direction of the drive roll and the longitudinal direction of the endless belt is completely reduced due to imbalance of the tension by the tension roll. Drive angle
This is the result of the force acting on the endless belt in the width direction in addition to the force moving the endless belt in the longitudinal direction from the endless belt to the endless belt (hereinafter sometimes referred to as the shift movement force). In the fixing device shown in (1), the deviation movement force F is received by the rib a 'loosely fitted in the roll groove d' to prevent the deviation movement.

In the surf type fixing device shown in FIG. 4A, the inner surface of the endless belt A 'and the heater 4'
There is a fear that the endless belt A 'is worn out and thinned due to the sliding contact with the endless belt. As shown by the dotted line in (b), yield bending deformation occurs, and this is compressed by a pressure roll, which may cause wrinkles or cracks. Even if the thickness of the endless belt can be sufficiently maintained, there is a fear that the rib may be broken as a result of the above-mentioned shifting movement force acting on the rib and the shifting may not be reliably prevented.

SUMMARY OF THE INVENTION An object of the present invention is to provide an endless belt for an electrophotographic recording apparatus which can reliably prevent the endless belt from shifting in a belt type electrophotographic recording apparatus.

[0007]

According to the present invention, there is provided an endless belt for an electrophotographic recording apparatus, wherein a rib is provided on at least one end of the endless belt, and the endless belt is hung on a group of rolls. An endless belt of an electrophotographic recording apparatus in which tension is applied to the endless belt by a tension roll in the roll to prevent the belt from shifting by loosely fitting the roll onto a roll or a guide. The solid lubricant comprises a resin film containing 0.5 to 5% by weight of a solid lubricant. The solid lubricant includes a fluororesin, a fluoroelastomer, a fluoroelastomer, graphite or graphite bonded to fluorine. Carbonized,
One or more powders of silicone resin, silicone rubber, silicone elastomer, silica, alumina, titanium oxide, and magnesium oxide can be used, and the friction coefficient of the inner surface is 0.2 or less.

The endless belt for an electrophotographic recording apparatus according to the present invention can be used for an endless belt of a toner image transfer or intermediate transfer device in addition to a toner image fixing device. It can be made semiconductive by being included.

The surface roughness (the average roughness Rz according to JIS B0601) of the inner and outer surfaces of the endless belt for an electrophotographic recording apparatus according to the present invention is usually 5 μm or less.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a side view of a surf type fixing device using an endless belt according to the present invention, FIG. 1B is a plan view thereof, and FIG. FIG. 1D shows a cross-sectional view taken along line II-II of FIG. 1B. In FIG. 1, 1 is a drive roll, 2 is a tension roll, A is an endless belt hung on these rolls, and 3 is a heat roller internally provided on the endless belt A.
The endless belt A is in a tensioned state by the tension roll 2. Reference numeral a denotes a rib attached to both ends of the width of the inner peripheral surface of the endless belt with an adhesive b. A groove d is provided on the outer peripheral surfaces of the driving roll 1 and the tension roll 2, and the rib a is loosely inserted into the groove d. It is fitted. Reference numeral 4 denotes a pressure roll (following roll) which is circumscribed to the endless belt A so as to face the heater 3.

The endless belt A is made of a heat-resistant synthetic resin film and contains a solid lubricant. Therefore, it has excellent wear resistance, a friction coefficient (according to JIS K7118) of 0.2 or less, and extremely low friction.

FIG. 1C or FIG. 1D shows a state in which the shifting movement force F of the endless belt A is supported by the rib a. As described above, this displacement movement force is applied to the drive roll due to the tension roll imbalance due to the tension roll.
The result is that the angle between the axial direction of the roller and the longitudinal direction of the endless belt does not become a perfect right angle, but a force acts on the endless belt in the width direction from the driving roll.
If this deviation movement force is to be greater than the lateral movement frictional force between the drive roll and the endless belt, lateral slide occurs, and the drive roll transmits the widthwise movement force to the endless belt. Is not performed, so that no force greater than the lateral moving frictional force acts on the rib.

In the endless belt according to the present invention, the friction coefficient of the inner surface is reduced to 0.2 or less by the addition of the solid lubricant. Even if the ribs are attached with an adhesive, the base of the ribs can be stably held and the endless belt can be surely prevented from shifting. Further, the addition of the solid lubricant makes it possible to extremely increase the wear resistance of the endless belt, and prevents the inner surface of the endless belt from being worn in spite of the sliding contact with the heater to reduce the thickness of the endless belt in the initial state. The endless belt can be prevented from yielding bending deformation due to the lateral force acting on the ribs. When the yielding bending deformation occurs, the yielded portion is compressed by a pressure roll, and wrinkles or the like are generated. The occurrence of cracks can be eliminated.

The yield bending deformation of the end of the endless belt due to the lateral force acting on the rib is more likely to occur as the elastic modulus decreases and the belt thickness decreases.
In the endless belt according to the present invention, since the lateral force acting on the ribs can be sufficiently reduced as described above, it is sufficient that the product of the elastic modulus and the thickness is about 15 kg / mm.

In the above embodiment, a rib is provided on at least one end of the inner surface of the endless belt, and the rib is loosely fitted in the groove of the roll. However, as shown in FIG. A rib a may be provided at least on one end, and the rib a may be loosely fitted into a groove d of the guide 5 provided facing each roll (the driving roll 1 and the tension roll 2).

The endless belt according to the present invention can also be used as an endless belt for a belt type electrophotographic recording apparatus other than the above-mentioned fixing device. FIG. 3 shows an example of an intermediate transfer type electrophotographic apparatus, in which the endless belt according to the present invention is used as an intermediate transfer endless belt. In FIG.
Reference numeral 6 denotes a photosensitive member which forms an electrostatic latent image by exposure, and a toner of opposite polarity is attached to the electrostatic latent image by a normal image method (or a reversal developing method) with a suction force (or a toner having the same polarity is charged). This is a photosensitive drum that is developed by being attached to a non-charged portion by a repulsive force. Reference numeral A denotes an endless belt according to the present invention, which is suspended between a driving roll 1 and a driven roll 2, and is a low-resistance body formed by blending conductive particles such as carbon. The charged toner image is suction-transferred by the electrostatically induced charge on the endless belt A at the contact area of the contact point, and the charge released by the transfer is released to the ground at the ground roll 7. Reference numeral 8 denotes a print sheet for the intermediate transfer toner image 9
This is a transfer roll for transferring the image to the printer.

The endless belt according to the present invention can also be used as an endless belt of a transfer device. For example, in FIG. 3, the roll 8 is omitted, and the recording paper is passed between the photosensitive drum 6 and the endless belt A. Then, the charged toner image on the photosensitive drum is suction-transferred onto the recording paper 91 by the electrostatic induction charge on the endless belt A, carried out from the endless belt A, and then used as an endless belt A for fixing by a fixing device. Can also be used.

In these cases, conductive powder is added to the endless belt in addition to the solid lubricant, and its volume resistance value is 10 ⁹ to 10 ¹⁵ Ω.cm or 10 ⁹ to 10 ^14.
Ω.cm, or 10 ¹³ to 10 ¹⁶ Ω.cm.

The endless belt according to the present invention can be formed from a resin solution obtained by adding a solid lubricant to a heat-resistant resin such as polyimide, polyimide amide, polybenzimidazole or polyamide.

The lubricant may be a fluororesin powder, for example, polytetrafluoroethylene powder, polyvinylidene fluoride powder, ethylene-tetrafluoroethylene copolymer powder, tetrafluoroethylene-perfluoroalkylvinyl ether. Copolymer powder, tetrafluoroethylene-
Fluororesin powder such as hexafluoropropylene polymer powder, fluoroelastomer powder, fluororubber powder, carbon fluoride powder obtained by bonding fluorine to graphite or graphite,
One or more of inorganic powders of silicone resin powder, silicone rubber powder, silicone elastomer powder, silica, alumina, titanium oxide, and magnesium oxide can be used, and the powder diameter is uniformly dispersed. 0.01-5.0μ for
m, preferably 0.1 to 1.0 μm. As long as lubricity is not impaired, surface treatment, polymer-graft treatment, or addition of a dispersant can be performed to improve dispersibility.

The amount of the above lubricant added is 0.5 to 5% by weight based on the weight of the resin in the resin solution. If it exceeds 5% by weight, the coefficient of friction becomes 0.05 or less, so that chatter and slip are easily generated between the endless belt and the drive roll,
If the content is less than 0.1% by weight, it is difficult to set the friction coefficient to 0.2 or less.

The endless belt according to the present invention is formed by, for example, a centrifugal molding method in which a lubricant-added resin solution is applied to the inner surface of a rotary cylindrical mold, centrifugally molded to a uniform thickness, and then dried and solidified. Apply the lubricant-added resin solution to the inner surface, support it vertically, drop the core mold to run and spread the coating solution on the inner surface to a uniform thickness, and then dry and solidify. A spreading method of applying a lubricant-added resin solution, passing the solution through an outer mold, spreading the coating solution to a uniform thickness, and then drying and solidifying the solution can be used. If necessary, the mold may be subjected to a mold release treatment, or a defoaming treatment may be performed during the molding process. In these molding methods, the surface smoothness of the mold and the core is set so that the inner and outer surfaces of the endless belt have a surface roughness of 5 μm or less.

A high elastic layer, a release layer, an oil-resistant layer or an abrasion-resistant layer,
For example, a silicone rubber layer, a fluorine rubber layer or a fluorine resin layer can be added.

The endless belt according to the present invention is made of a polyimide resin in which lubricant powder and conductive powder are dispersed, and can be formed from a polyamic acid solution in which polytetrafluoroethylene powder and carbon are dispersed. This powder-dispersed polyamic acid solution is obtained by dispersing a lubricant powder and a conductive powder in a solvent by ball milling or ultrasonic stirring, and dissolving approximately equimolar amounts of tetracarboxylic dianhydride or a derivative thereof and a diamine in the solvent. A method for synthesizing a polyamic acid solution by reacting in a solvent, dispersing a conductive powder in a solvent by ball milling or ultrasonic stirring, and dissolving approximately equimolar amounts of tetracarboxylic dianhydride or a derivative thereof and a diamine in the solvent Reacting a polyamic acid solution, dispersing a lubricant in the polyamic acid solution, and mixing a lubricant and a conductive powder in a polyamic acid solution synthesized by an ordinary method with a planetary mixer, a bead mill, or a three-piece roasting machine. Can be obtained by a method such as dispersing in a solvent or the like.

To form this polyimide resin film tubular body, the above-mentioned powder-dispersed polyamic acid solution is applied to the inner surface of a rotary cylindrical mold, which is centrifugally formed to a uniform thickness, and then heated to form a polyamide. A method in which the acid is imidized and the solvent is removed can be used. In this case, about 80
It is preferable to use a two-stage heating method of evaporating and removing ring-closing water and a solvent generated during the imide conversion at a relatively low temperature of ~ 180 ° C and then raising the temperature to 250 to 400 ° C to complete the imide conversion.

Examples of the conductive powder include carbon black such as Ketjen black and acetylene black.
Metal powder (for example, aluminum and nickel), semiconductive powder (for example, a metal oxide compound such as tin oxide, potassium titanate) and conductive polymer (for example, polyaniline) powder can also be used.

The rib is made of a heat-resistant resin film, for example, a heat-resistant resin such as the above-mentioned polyimide or the like, having a melting point of 200 ° C.
A strip of the above-mentioned film of polycarbonate, polyethylene terephthalate, etc.) can be provided by fixing it with an adhesive.
Heat-resistant elastomers, pot-melt adhesives, heat-curable adhesives, pressure-sensitive adhesives and the like can be used. In order to provide the rib, it is also possible to provide a rib forming groove in a molding die and provide the rib simultaneously with the molding of the endless belt.

[0028]

EXAMPLES Example 1 Dry carbon black was treated with N
1-Methyl-2-pyrrolidone was mixed with 1% by weight of a tetrafluoroethylene-per-fluoroalkylvinyl ether copolymer powder (average particle size: 5 μm) based on 100% of polyimide to be synthesized. % By weight and mixed with a ball mill at room temperature for 6 hours.
An equimolar amount of 4'-diaminobiphenyl ether has a concentration of 20.
%, And a polymerization reaction was carried out while stirring at room temperature for 4 hours in a nitrogen atmosphere to obtain a 2,000 poise polyamic acid solution. This polyamic acid solution is 300 m inside diameter
m, applied to the inner peripheral surface of a cylindrical mold having a length of 500 mm with a dispenser to a thickness of approximately 400 μm, and rotated at 1500 rpm for 10 minutes to obtain a developed film having a uniform thickness.
While rotating at rpm, hot air of 60 ° C. was blown from the outside of the mold for 30 minutes, then heated at 150 ° C. × 60 minutes, and then heated to 300 ° C. at a heating rate of 2 ° C./min. Then, the solvent was removed, dehydrated ring-closing water was removed, and imide conversion was performed. The following endless belt was obtained. The endless belt according to the present invention was prepared by bonding a urethane rubber strip (hardness: 50 °) having a width of 4 mm and a thickness of 1.5 mm to both ends of the inner peripheral surface of the endless belt with a double-sided adhesive tape.

This endless belt with ribs was incorporated in a fixing device having the structure shown in FIG. 1, and after rotating the endless belt at a speed of 2 m / min for 200 hours, a 100-sheet paper-pass test was performed. Obtained. When the belt thickness was measured after the paper passing test, it was found that the original thickness was substantially maintained. No peeling or breakage of the ribs and no yield bending at the width end of the belt were observed at all.

Example 2 Equimolar 3,3 ', 4,4'
-Biphenyltetracarboxylic dianhydride and p-phenylenediamine in N-methyl-2-pyrrolidone at a concentration of 20
Wt% and dissolved in a nitrogen atmosphere at room temperature.
The polymerization reaction was carried out with stirring for a time to obtain a polyamic acid solution having a viscosity of 2000 poise. To this polyamic acid solution, a polytetrafluoroethylene powder (average particle size: 4.1 μm) was added so as to be 2% by weight with respect to the polyimide, and carbon black was added so as to be 2% by weight with respect to the polyimide. And kneaded with a triple roll to uniformly disperse.
Using this polyamic acid solution, an endless belt having a thickness of 55 μm was obtained in the same manner as in Example 1, and a urethane rubber strip was adhered with a double-sided adhesive tape to prepare an endless belt according to the present invention.

The product of this example was subjected to a paper-passing test on 100 sheets after rotating for 200 hours in the same manner as in Example 1, and a good image was obtained. After the paper-passing test, the belt thickness was measured. No peeling or breakage of the ribs and no yield bending at the belt width end were observed at all.

Example 3 Instead of adding 2% by weight of polytetrafluoroethylene powder to Example 2, adding silicon powder (average particle size: 3 μm) to 2.5% by weight. The procedure was the same as in Example 2 except for the above. A good image was obtained when a 100-sheet running test was performed on the product of this example after 200 hours rotation in the same manner as in Example 1. When the belt thickness was measured after the running test, the original thickness was substantially maintained. No peeling or breakage of the ribs and no yield bending at the width end of the belt were observed.

Comparative Example 1 The procedure was the same as in Example 1 except that the addition of the lubricant was omitted. The coefficient of friction of the inner surface of the endless belt exceeded 0.2. When this comparative product was rotated for 200 hours in the same manner as in Example 1, generation of abrasion powder was observed. Further, when a paper passing test was performed on 100 sheets, image disorder was observed. Float corresponding to was observed.

Comparative Example 2 The procedure of Example 2 was repeated except that the amount of the polytetrafluoroethylene powder was 5.5% by weight. The coefficient of friction of the inner surface of the endless belt was 0.05 or less. After rotating for 200 hours in the same manner as in Example 1,
When a sheet passing test was performed, no abrasion powder was generated, but slip occurred frequently and a satisfactory image was not obtained.

[0035]

According to the present invention, in an electrophotographic recording apparatus of a belt type, a shift of the endless belt caused by an unbalanced tension of a tension roll is prevented by using a rib provided on the endless belt as a stopper. In this case, the friction characteristics and wear resistance of the endless belt are modified so that the shift movement force acting on the ribs is made sufficiently small, and the endless belt is deformed so that the yield bending deformation of the belt end due to the shift movement force can be eliminated. Since the thickness of the belt can be sufficiently maintained as it is, the belt-type electrophotographic recording apparatus can be driven stably without the endless belt shifting. Therefore, a complicated sensor-control mechanism for preventing the displacement is not required, and the cost of the apparatus can be reduced and the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a drawing showing an example of a use state of an endless belt according to the present invention.

FIG. 2 is a drawing showing another example of the use state of the endless belt according to the present invention.

FIG. 3 is a drawing showing another example of the use state of the endless belt according to the present invention.

FIG. 4 is a view showing a conventional surf-type fixing device.

[Explanation of symbols]

 A Endless belt a Rib 1 Driving roll 2 Tension roll d Groove 3 Heater 4 Pressure roll 5 Guide 6 Photosensitive drum 7 Grounding roll 8 Transfer roll

Continued on the front page (72) Inventor Toshihiko Tomita 1-2-1 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 2H032 AA05 BA09 BA18 BA23 2H033 AA23 BA11 BB26 BB37 3F049 BA12 BA13 BB11 LA02 LB03

Claims (4)

[Claims] An endless belt is provided with ribs on at least one end thereof, the endless belt is hung on a group of rolls, and tension is applied to the endless belt by a tension roll in the rolls. An endless belt for an electrophotographic recording apparatus for preventing the belt from shifting by loosely fitting the rib onto a roll or loosely onto a guide, comprising a resin film containing 0.5 to 5% by weight of a solid lubricant. An endless belt for an electrophotographic recording device. 2. A solid lubricant comprising a fluororesin, a fluoroelastomer, a fluoroelastomer, a fluorocarbon having graphite or graphite bonded to fluorine, a silicone resin, a silicone rubber, a silicone elastomer, silica, alumina, 2. The endless belt for an electrophotographic recording apparatus according to claim 1, wherein the endless belt is one or two or more kinds of powders of titanium oxide and magnesium oxide. 3. The endless belt for an electrophotographic recording apparatus according to claim 1, wherein the coefficient of friction of the inner surface is 0.2 or less. 4. The endless belt for an electrophotographic recording apparatus according to claim 1, wherein the endless belt is made semiconductive by containing a conductive powder.