JP2001066917A - Film tubular body for image fixing device and image fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent the slip of recording paper without interposing a lubricant between a film tubular body and an elastic body and to simplify a fixing device by disposing a low-friction sheet on the elastic body and providing the outside surface of the film tubular body with a release layer having the coefficient of friction larger than the coefficient of friction of the low-friction sheet. SOLUTION: A fixing roll 1 of a drive type of the image fixing device is constituted by providing the outer periphery of a metallic roll 12 into which a heater 11, such as a halogen lamp, is built, with a heat resistant elastic layer 13 consisting of silicone rubber, etc. An endless casting film, etc., are usable for the heat resistant film tubular body 2 circumscribing the fixing roll 1 and the surface thereof is provide with the release layer 21 having the coefficient of friction larger than the coefficient of friction of the low-friction sheet 33 on the elastic body 32. A pressing unit A is constituted by mounting the elastic body 32 on a supporting base 31 and putting the low-friction sheet 33, for example, glass cloth impregnated with a fluororesin on the elastic body 32 and bonding both ends of the low-friction sheet 33 to the supporting body 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, a copying machine,
The present invention relates to a film tubular body for an image fixing device used for forming an electrophotographic image in a facsimile or the like, and an image fixing device.

[0002]

2. Description of the Related Art In electrophotographic image formation in printers, copiers, facsimile machines, and the like, a process of fixing a toner image by passing a recording paper having an unfixed toner image formed thereon through a fixing device and applying heat and pressure to the toner image is sometimes performed. Various methods have been proposed as such a fixing device, and as a basic method, as shown in FIG. 2A, a driving-type fixing device having a built-in heat source 11 ′ such as a halogen lamp is used. A nip region n 'is formed by circumscribing a driven pressurizing roll 2' to the roll 1 'and pressing the outer peripheral elastic layers 12' and 22 'of the rolls 1' and 2 '. There is known a method in which a pressure roll 2 'is driven by driving a roll 1', and a recording paper 4 'is passed through a nip area to fix an unfixed toner image on the recording paper by heating and pressing.

However, in this method, the elastic layers of both rolls must be thickened in order to set the width of the nip region n 'to a predetermined width. However, there are problems such as an increase in the nip pressure of the lubrication and durability of the elastic layer. In order to solve such a problem, as shown in FIG. 2B, a driving type fixing roll 1 'incorporating a heat source 11' is used.
And a film tubular body 2 ″ is disposed with its outer surface in contact with
An elastic body 3 'is provided on the inner surface side of the film tubular body 2 ",
The elastic body 3 'and the drive roll 1' hold the tube wall of the film tubular body 2 ", and the drive roll 1 'drives the drive roll.
A method has been proposed in which the recording paper 4 'is passed between the tape 1' and the film tubular body 2 ", and the film tubular body 2" is rotated while sliding on the elastic body 3 '.

[0004] In any of the above methods, measures for preventing offset are required. Thus, in the method shown in FIG. 2A, it is necessary to provide a release layer on the outer peripheral surface of the fixing roll 1 'and the outer peripheral surface of the pressure roll 2'. In the method shown in (b), it is necessary to provide a release layer on the outer peripheral surface of the fixing roll 1 'and the outer peripheral surface of the film tubular body 2 ". As such a release layer, a fluororesin layer, a mirror surface Finished silicone rubber layers and fluorine rubber layers are known, and the friction coefficient of the release layer is usually less than 0.35.

[0005]

In the method shown in FIG. 2A, the friction sliding portion is a driven pressure roller 2 'bearing, and the friction coefficient of this bearing is extremely small. ,
Even if the coefficient of friction of the outer peripheral surfaces of the fixing roll 1 'and the pressure roll 2' is considerably reduced due to the release layer, the distance between the fixing roll 1 'and the recording paper 4' is reduced. The friction coefficient μa and the friction coefficient μb between the pressure roll 2 ′ and the recording paper 4 ′ do not become smaller than the friction coefficient μc of the bearing of the pressure roll 2 ′.
Slip does not occur between the fixing roll 1 'and the recording paper 4' or between the pressure roll 2 'and the recording paper 4'.

However, in the method shown in FIG. 2B, since the coefficient of friction μc between the film tubular body 2 ″ and the elastic body 3 ′ is considerably high, the outer peripheral surface of the fixing roll 1 ′ and When the friction coefficient μa, μb of the outer peripheral surface of the film tubular body 2 ″ is reduced due to the formation of the release layer,

## EQU1 ## It is difficult to satisfy the relationship of μa, μb> μc, and slip occurs between the film tubular body 2 ″ and the recording paper 4 ′ or between the fixing roll 1 ′ and the recording paper 4 ′. The toner image is disturbed.

Therefore, it has been proposed to coat the surface of the elastic body with a low friction sheet, and to interpose a lubricant at the sliding contact interface between the coating layer and the tubular film (Japanese Patent Laid-Open No. 10-1998).
No. 213984). However, it is not easy to hold the fluid lubricant stably at the sliding interface, and under the depletion of the lubricant, the relationship of the above formula cannot be maintained, and the image is distorted due to the slip of the recording paper. Is inevitable.

As described above, the friction coefficient of the conventionally used release layer is low (less than 0.35), and the release layer shown in FIG.
With respect to the method of (1), the relationship of the formula is not satisfied due to the decrease of μa and μb due to the formation of the release layer. To reduce μc.

An object of the present invention is to use a release layer having a friction coefficient larger than that of a low friction sheet on an elastic body on the outer surface of the film tubular body in the method shown in FIG. An object of the present invention is to satisfy the above equation without intervening a lubricant at a sliding contact interface between the film tubular body and the elastic body. That is, an object of the present invention is to dispose a film tubular body on a drive roll having a built-in heater with its outer surface in contact with an outer surface thereof, dispose an elastic body on the inner surface side of the film tubular body, And the drive roll sandwiches the tube wall of the film tubular body, and by driving the drive roll, the recording paper passes between the drive roll and the film tubular body, and the film tubular body becomes an elastic body. In a fixing device that rotates while sliding, even if a release layer is provided on the outer peripheral surface of the driving roll and the outer peripheral surface of the film tubular body, a lubricant is not interposed between the film tubular body and the elastic body. An object of the present invention is to simplify the apparatus by making it possible to prevent the recording paper from slipping.

[0010]

According to the present invention, there is provided a film tubular body for an image fixing device, wherein the film tubular body is disposed in such a manner that its outer surface is brought into contact with a driving roll having a built-in heater. An elastic body coated with a low friction sheet is disposed on the inner surface of the film, and the elastic body and the drive roll sandwich the tube wall of the film tubular body, and the drive roll is driven by the drive roll. A film tubular body in a fixing device in which a recording paper is passed between the film tubular body and the film tubular body is rotated while sliding on the elastic body coated with a low friction sheet. The configuration is characterized in that a release layer having a friction coefficient larger than the friction coefficient is provided on the outer surface.

In the image fixing apparatus according to the present invention, a film tubular body is disposed on a driving roll having a built-in heater with its outer surface in contact with the driving roll, and a low friction sheet is provided on the inner surface side of the film tubular body. A coating elastic body is provided, and the elastic body and the driving roll sandwich a tube wall of the film tubular body. The driving roll drives the recording paper between the driving roll and the film tubular body. Is a fixing device for rotating the film tubular body while sliding the film tubular body on the low friction sheet coated elastic body, and having a friction coefficient larger than the friction coefficient of the low friction sheet on the elastic body on the outer surface of the film tubular body. And the friction coefficient between the recording paper and the film tubular body is set to be 1.1 times or more the friction coefficient between the film tubular body and the elastic body.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a drawing showing an image fixing device according to the present invention. In FIG. 1, reference numeral 1 denotes a driving type fixing roll. A heat-resistant elastic layer 13 such as silicone rubber or fluorine rubber is provided on the outer periphery of a metal roll 12 having a heater 11 such as a halogen lamp built therein. It is provided. Reference numeral 2 denotes a heat-resistant film tubular body circumscribed to the fixing roll 1, which can use an endless casting film, an endless bonding film, or the like, and has a friction coefficient larger than a friction coefficient of a low friction sheet on an elastic body described later. A release layer 21 is provided on the surface. A indicates a pressing unit, and an elastic body 3 is provided on a support base 31.
2 (a heat-resistant elastomer such as silicone rubber), a low-friction sheet 33, for example, a glass cloth impregnated with a fluororesin, is put on the elastic body 32, and both ends of the low-friction sheet 33 are supported on a support base 31. It is tied to 34 is a spring,
The use of air or oil cylinders is also possible.

The surface of the low friction sheet 33 of the pressing unit A is inscribed in the film tubular body 2, and the elastic pressing member 32 is pressed against the fixing roll 1 by the compressive stress of the spring 34 to be compressed and deformed. A nip is formed between the film 1 and the film tubular body 2. Reference numeral 34 denotes a traveling guide for the film tubular body 2, which is fixed to the support table 31.

In FIG. 1, reference numeral 4 denotes a recording sheet on which an unfixed toner 41 is formed. In FIG. 1, in order to fix a toner image, the fixing roll 1 is heated by a built-in heater 11, and a sensor (shown in FIG. 1) indicates that the surface temperature of the fixing roll 1 has reached a predetermined temperature. Is not detected)
The recording paper 4 is caused to pass through the nip portion by rotating the nozzle 1.

The friction coefficient μa between the fixing roll 1 and the recording paper 4 and the friction coefficient μb between the recording paper 4 and the film tubular body 2 are determined by the low friction sheet 33 on the surface of the elastic pressing member and the film. The coefficient of friction between the tubular body 2 and the friction coefficient μc is set to 1.1 times or more, preferably 1.3 times, and abrasion occurs on the sliding contact surface between the low friction sheet 33 and the film tubular body 2 to reduce μc. Even if it increases a little,

## EQU2 ## The condition of μa, μb> μc can be satisfied.

The base material of the film tubular body used in the present invention is a resin excellent in heat resistance and abrasion resistance, for example, polyimide, polyamideimide, polybenzimidazole, polyetheretherketone, polyethersulfone. And the like, but polyimide and polyamideimide are particularly preferred. Add fillers such as organic particles, inorganic particles, metal particles, metal oxide particles, etc. to the base material to impart low friction with the pressing member, wear resistance, thermal conductivity, conductivity, etc. Can also. For this film tubular body, a method of joining a film endlessly and a method of seamlessly casting can be used. As the casting method, a method of applying a precursor solution in a cylindrical mold and centrifugally forming the solution, a method of forming a cylindrical shape, There are a method of dipping the precursor solution in the mold, a method of applying the precursor solution in the cylindrical mold, and then dropping the bullet traveling body.

As the low friction sheet 33, a fluororesin sheet, a fluororesin layer formed on both sides of a heat-resistant fiber cloth base material, and fired can be used. Glass cloth and carbon fiber cloth having a thickness of 30 μm to 600 μm are preferable. This fluorocarbon low friction sheath
In the production of the heat-resistant fiber cloth substrate, a method of applying an aqueous dispersion of a fluororesin to both surfaces of the heat-resistant fiber cloth substrate, or impregnating the dispersion with the substrate by a dipping method, and then firing the substrate. Can be used. In this case, the thickness after firing is 5
The coating amount of the fluororesin is adjusted so as to be 0 μm to 1000 μm. The adhesion amount of the fluororesin varies depending on the thickness of the fluororesin layer to be formed, but is 50 g / m ² to 10 g / m ^2.
It is preferably 0 g / m ² . If it is less than 50 g / m ² , it is difficult not only to satisfy the above-mentioned condition of the coefficient of friction even if it is fired, but also the abrasion of the fluororesin layer exposes the fibrous fabric base material to cause early abrasion damage of the inner surface of the film tubular body. If it exceeds 100 g / m ² , the thickness of the low friction sheet becomes unnecessarily thick. If the degree of calcination of the fluororesin is low, the binding force between the fluororesins becomes low, and the abrasion resistance and the friction characteristics are reduced. Therefore, it is safe to calcinate to a crystallinity of 30% or more. As the above-mentioned fluororesin, polytetrafluoroethylene is most suitable in terms of heat resistance and mechanical properties.

The coefficient of friction is such that the low friction sheet 33 on the elastic body is used.
Silicone rubber or fluoro rubber can be used for the release layer 21 having a friction coefficient smaller than the above. Particularly, use of room temperature curing silicone rubber, low temperature curing silicone rubber, fluorosilicone rubber, vinylidene fluoride rubber, etc. It is preferable that the coating be performed by spray coating or dip coating, and it is preferable that the coating be performed after applying a primer.

In the present invention, the coefficient of friction of the release layer 21 on the outer peripheral surface of the film tubular body 2 is determined by adjusting the coefficient of friction of the low friction sheet 3 on the elastic body.
3, the friction coefficient .mu.b between the film tubular body 2 and the recording paper 4 is reduced by the friction between the low friction sheet 33 on the surface of the elastic body 32 and the film tubular body 2. It can be surely larger than the coefficient μc. That is, the coefficient of friction of the recording paper 4 is larger than the coefficient of friction of the base material (heat-resistant plastic film) of the film tubular body, and the coefficient of friction of the release layer 21 on the outer surface of the film tubular body has a low friction coefficient on the elastic body. Since the friction coefficient μb between the film tubular body 2 and the recording paper 4 is larger than the friction coefficient
The coefficient of friction μc between the low-friction sheet 33 on the sheet 2 and the film tubular body 2 can be reliably increased. In addition, the fixing roller
The coefficient of friction μa between the heat-resistant elastic layer (silicone rubber) 13 on the outer periphery of the tape 1 and the recording paper 4 and the coefficient of friction μc between the low-friction sheet 33 on the elastic body 32 and the film tubular body 2 are also ensured. Can be larger. That is, the coefficient of friction of the recording paper 4 is larger than that of the film tubular body itself (heat-resistant plastic film), and the coefficient of friction of the silicone rubber layer 13 on the outer periphery of the fixing roll 1 is elastic. Since the friction coefficient of the low friction sheet 33 on the roller 32 is larger, the friction coefficient μa between the heat-resistant elastic layer (silicone rubber) 13 on the outer periphery of the fixing roll 1 and the recording paper 4 is Low friction sheet 33
And the friction coefficient μc between them can be more reliably increased. Therefore, in the present invention, despite the provision of the release layer on the outer peripheral surface of the fixing roll and the outer peripheral surface of the film tubular body,

## EQU00003 ## The condition of .mu.a, .mu.b> .mu.c can be surely satisfied, and clear double-sided copying can be guaranteed by eliminating the slip of the recording paper.

[0020]

EXAMPLES In the following Examples and Comparative Examples, fixing rollers were used.
Has an outer diameter of 30 mmφ, a peripheral speed of 160 mm / sec, and a length of 36 mm.
0 mm and an outer surface temperature of about 150 ° C. are used, and the dimensions of the film tubular body are 94 mm in circumference and 320 mm in length.
Fluororesin coated and fired glass fiber sheet having a friction coefficient of 0.15 was applied to the elastic pressing member by a width of 10 mm and a thickness of 5 m.
m, a silicone rubber body having a length of 320 mm was used. This fluororesin coated and fired glass fiber sheath
Is impregnated with an aqueous dispersion of polytetrafluoroethylene having a solid content of 40% (adhesion amount: 280 g / m ² ) on a plain woven glass fiber substrate having a thickness of 250 μm, and baked to obtain a thickness of 32 μm.
One having a thickness of 0 μm and a firing crystallinity of 34% was used. A spring having a compression force of 30 kg was used.

[Example] After the polyamic acid solution was supplied to the inner peripheral surface of the mold, the core was run to make the coating thickness uniform,
After further drying, solvent removal and imide conversion were performed, and the thickness was 75 μm.
m of the polyimide film tubular body was obtained. A primer treatment is applied to the outer peripheral surface of the film tubular body, and a room-temperature-curable silicone rubber is spray-coated thereon to form a 20 μm-thick film.
A silicone rubber release layer was provided. The friction coefficient of this release layer was 0.5 or more, which was larger than the friction coefficient (0.15) of the low friction sheet (fluorine resin coated / fired glass fiber sheet). When this film tubular body was incorporated into a fixing device and double-sided copying of 500 sheets was performed, no disturbance of the image was observed, toner was not attached to the surface of the film tubular body, and the releasability was good.

[Comparative Example 1] After a polyamic acid solution was supplied to the inner peripheral surface of a mold, a core was run to make the coating thickness uniform, and further heated and dried, followed by a primer treatment to perform perfluoroalkyloxy. An aqueous dispersion of a fluororesin (PFA) is spray-coated, and then the imide conversion is performed simultaneously with the firing of the PFA layer to obtain a polyimide film having a thickness of 75 μm.
A film tubular body having a PFA release layer thickness of 15 μm was obtained. The friction coefficient of the release layer of this film tubular body is 0.12, which is slightly smaller than the friction coefficient (0.15) of the low friction sheet (fluorine resin coated / fired glass fiber sheet). Was. When this film tubular body was incorporated in a fixing device and double-sided copying was performed, image disturbance was observed on 400 out of 500 sheets. However, no toner was adhered to the surface of the film tubular body, and the releasability was good.

[Comparative Example 2] After the polyamic acid solution was supplied to the inner peripheral surface of the mold, the core was run to make the coating thickness uniform, and further dried to remove the solvent and perform imide conversion to obtain a thickness of 7
A polyimide film tubular body of 5 μm was obtained. The coefficient of friction of this film tubular body was 0.25,
(Fluorine resin coated / fired glass fiber sheet). When this film tubular body was incorporated into a fixing device and double-sided copying was performed, image disturbance was about 50 out of 500 and the image clarity was relatively good. However, since there was no release layer, adhesion of toner to the surface of the film tubular body was remarkable, and the releasability was poor.

The coefficient of friction is in accordance with JIS K 7218, and a coefficient of friction measuring device EFM- manufactured by Toyo Baldwin Co., Ltd.
It measured using III-F.

[0025]

According to the present invention, the film tubular body is circumscribed to the heat-fixing drive roll, and the low-friction sheet-covered elastic pressing member is inscribed in the circumscribed portion of the film tubular body.
In a fixing device in which a nip portion is formed between the heat fixing roll and the film tubular body, the friction coefficient of the release layer of the film tubular body is higher than the friction coefficient of the low friction sheet. The slippage of the recording paper is eliminated by satisfying the above condition without interposing a lubricant between the low friction sheet coated elastic pressing member and the film tubular body, and the toner film tubular body and the fixing member are fixed. It is possible to improve image quality and fixability by eliminating the adhesion to the roll.

[Brief description of the drawings]

FIG. 1 is a view showing an image fixing device according to the present invention.

FIG. 2 is a diagram illustrating a conventional image fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roll 2 Film tubular body 21 Release layer 32 Elastic pressing member 33 Low friction sheet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tokio Fujita 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Yoshiya Takayama 1-1-1, Shimohozumi, Ibaraki-shi, Osaka No. 2 Inside Nitto Denko Corporation (72) Inventor Takufumi Kamijo 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 2H033 AA02 BA11 BA12 BB05 BB06 BB39 BD07

Claims (4)

[Claims] A film tubular body is disposed on a drive roll having a built-in heater with its outer surface in contact with an outer surface thereof, and a low friction sheet coated elastic body is disposed on an inner surface side of the film tubular body. The elastic member and the driving roll sandwich the tube wall of the film tubular body, and the driving roll drives the recording paper to pass between the driving roll and the film tubular body, and the film tubular body is moved. A film tubular body in a fixing device that rotates while sliding on an elastic body coated with a low friction sheet, wherein a release layer having a friction coefficient larger than that of the low friction sheet on the elastic body is provided on the outer surface. A film tubular body for an image fixing device, characterized by comprising: 2. The low friction sheet is made of fluororesin, and the release layer is made of silicone rubber or fluororubber.
A film tubular body for an image fixing device as described in the above. 3. A film roll is disposed on a drive roll having a built-in heater with its outer surface in contact with an outer surface thereof, and an elastic body coated with a low friction sheet is disposed on an inner surface of the film roll. The elastic member and the driving roll sandwich the tube wall of the film tubular body, and the driving roll drives the recording paper to pass between the driving roll and the film tubular body, and the film tubular body is moved. This is a fixing device that rotates while sliding on a low-friction sheet-covered elastic body. A release layer having a friction coefficient larger than the friction coefficient of the low-friction sheet on the elastic body is provided on the outer surface of the tubular film, and recording is performed. An image fixing device, wherein a coefficient of friction between paper and a film tubular body is 1.1 times or more as large as a coefficient of friction between a film tubular body and an elastic body. 4. The low friction sheet is made of fluororesin, and the release layer is made of silicone rubber or fluororubber.
The image fixing device as described in the above.