JPH11272104A - Fixing device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fixing device where the occurrence of off-setting is extremely reduced by incorporating an amorphous conductive metal oxide having a specified average particle size in a heating member. SOLUTION: This device possesses a thermally fixing roller 12 on whose inside a heat source 11 is provided and a pressure roller 13 brought into press- contact with the thermally fixing roller 12, and the pair of the rollers 12 and 13 are provided through the carrying path of a recording material 14. The thermally fixing roller 12 is constituted of a substrate 16 consisting of a hollow metallic tube and a mold-released layer 17 formed on it. The mold-released layer 17 incorporates a conductive agent so that adequate conductivity may be imparted, and the conductive agent is the amorphous conductive metal oxide whose average particle size is 1-100 nm. Preferably the volume resistivity of a metal oxide is <=10<8> Ω cm, and more preferably it is <=10<6> Ω cm. ZnO, TiO2 , SnO2 , Al2 O3 or the like are used as the metal oxide to be used, and it is most preferable to use SnO2 among them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device such as a heat roller fixing device or a film fixing device in a printer, a copying machine or the like utilizing an electrophotographic process.

[0002]

2. Description of the Related Art A heat roller fixing device and a film fixing device are disclosed in, for example, JP-A-8-220907,
This is known from, for example, Japanese Patent No. 237007. In such a fixing device, as a heating member for heating and fixing the toner image,
A substrate having a release layer such as tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) formed on a heat-resistant substrate is used. However, since PFA and PTFE have high insulating properties, the surface of the release layer is charged by friction with paper, and unfixed toner on paper is electrostatically attached to the surface of the fixing film, causing an electrostatic offset. . Such an electrostatic offset can be prevented by adding a conductive agent to the release layer to give the release layer an appropriate conductivity. A typical conductive agent used for this was carbon black.

[0003] However, carbon black is not always a satisfactory conductive agent, and it has been studied to employ various conductive agents to prevent electrostatic offset. For example, in JP-A-8-220907, it is disclosed in JP-A-9-23700 that an ionic conductive agent such as an organic phosphorus salt is contained in a release layer of a heating member.
No. 7 proposes that graphite powder be contained in a release layer of a heating member.

[0004]

The properties required of a heating member such as a roller fixing device are that heat resistance, mold release, thermal conductivity and conductivity are properly balanced.
In the above-described conventional example, these properties are not balanced, and the problem that offset is likely to occur due to resistance unevenness in a minute area has not been solved yet.

For example, in Japanese Patent Application Laid-Open No. 8-220907, a PF is used to form a release layer.
In the process of applying, drying, and sintering the dispersion liquid of A or PTFE, there is a problem that the composition is exposed to a high temperature of about 260 ° C., deteriorates, and the desired performance cannot be obtained, and the durability is poor. Further, in Japanese Patent Application Laid-Open No. 9-237007, there is a problem that electrostatic offset cannot be sufficiently prevented. That is, in order to impart appropriate conductivity to the release layer,
When graphite is made finer, the surface energy of the particles increases, and the particles are aggregated. As a result, it becomes difficult to uniformly disperse the conductive agent, so that microscopic resistance unevenness occurs. If there is micro-resistance unevenness, charging occurs in a very small high-resistance area, and the surface potential is disturbed in a very small area despite the low macro-resistance value of the heating member. Offset occurs, causing image stains and stains on the back surface of the recording material.

Accordingly, an object of the present invention is to solve such a problem in the prior art, and to provide a fixing device in which the occurrence of offset is extremely small.

[0007]

The object of the present invention is as follows.
(1) In a fixing device having a heating member that contacts a recording material having a toner image to heat the toner image and fixes the toner image on the recording material, the heating member may be an amorphous material having an average particle diameter of 1 to 100 nm. A fixing device comprising a conductive metal oxide, (2) a fixing device which contacts a recording material having a toner image,
In a fixing device having a heating member for heating a toner image and fixing the toner image on a recording material, the heating member includes a release layer that contacts a recording material having a toner image, and a base that supports the release layer, (3) the fixing device, wherein the release layer is a layer formed by applying a composition containing a conductive metal oxide sol dispersed in a colloidal state to the substrate. In a method of manufacturing a fixing device having a heating member for heating a toner image in contact with a recording material carrying a toner image and fixing the toner image, a sol of a conductive metal oxide dispersed in a colloidal state is included. And a method for manufacturing a fixing device, wherein the heating member is formed by applying a composition to a substrate.

In the present invention, the heating member used includes a heating roller or a heating film.

As the heating roller, PFA, P is applied to the peripheral surface of a cylindrical base such as aluminum, stainless steel or carbon steel.
One having a release layer made of TFE or silicone rubber or the like, or a silicone rubber layer on the peripheral surface of the base and a PF
A laminate of A or a PTFE layer is preferred.

A heat source is provided inside the heating roller to heat the surface of the heating roller to a temperature required for fusing and fixing the toner image, for example, 150 to 210 ° C. The heating roller is used together with the opposing pressure roller, and forms a nip by pressing against the pressure roller, and the recording material is nipped and conveyed by the nip to fix the toner image on the recording material.

The heating film has a thickness of 40 to 100 μm.
It is preferable that a release layer made of PFA or PTFE is formed on the surface of a heat-resistant film-like substrate such as polyimide of m. The heating film is preferably provided with a conductive layer in order to eliminate the influence of frictional charging that occurs when the heating film slides on a ceramic heater that is a heating element for heating the heating film.

The heating film moves while being supported by the heating element, and presses against a pressure member arranged opposite to form a nip. The nip sandwiches and conveys the recording material.
The toner image is heated and fixed in the nip.

As the heating element for heating the heating film, a heating resistor layer formed by printing on a ceramic substrate of alumina or the like and a glass layer as a protective layer formed thereon are used. The metal oxide dispersed in the release layer has the following characteristics.

As described above, in the fixing member of the present invention, the heating member such as the heating roller and the heating film is provided with the release layer having the releasability on the surface in contact with the recording agent. The release layer contains a conductive agent in order to impart appropriate conductivity.

This conductive agent has the following characteristics.

(1) In the present invention, the metal oxide contained as a conductive agent in the heating member has an average particle size of 1 to 100.
nm.

Here, the average particle diameter is an average particle diameter of 100 arbitrary particles among particles observed by an electron microscope. The particle size is the diameter of a circle when the projected surface of the observed particle is converted into a circle.

(2) In the present invention, the metal oxide contained in the release layer of the heating member is amorphous. The term “amorphous” as used herein refers to a substance having a broad scattering band having a half-value width of 5 ° or more having a peak at 20 from 70 ° to 20 ° by X-ray diffraction using CuKα radiation. Otherwise, it may have a crystalline diffraction line.

(3) Further, in the present invention, the metal oxide contained in the heating member is electrically conductive. The volume resistivity is preferably 10 ⁸ Ωcm or less, particularly preferably 10 ⁶ Ωcm or less.

The resistivity of the sample is 100 kg / cm ^2.
4cm in diameter and 0.2mm in thickness
cm of a cylindrical pellet, and the resistance (Ωcm) of the pellet was measured using a Hiresta AP (manufactured by Mitsubishi Yuka).

The metal oxides usable in the present invention include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In
₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ and the like can be used. Among them, ZnO, TiO ₂ , S
nO ₂ is preferred, and SnO ₂ is particularly preferred.

The above features (1) and (2) are features of the metal oxide dispersed in a colloidal state in the coating composition for forming the release layer.

That is, in the present invention, the metal oxide is colloidally dispersed in the composition applied to form the release layer. Particles having a diameter of 1 to 100 nm have a stable dispersion state of the metal oxide sol. Therefore, this size is called a colloidal dimension. This state is called colloidal state in the present invention.

The method for producing a colloidal metal oxide according to the present invention is a method for producing ultrafine metal oxide particles by dispersing them in an appropriate solvent, and a method for producing a metal compound soluble in a solvent by a decomposition reaction in the solvent. Any method such as a method can be adopted.

When the solvent of the tin oxide sol dispersion at the time of production has poor compatibility with the protective colloid binder, the solvent is replaced with a solvent suitable for dispersing in the binder. Or a compound capable of stably dispersing a metal oxide is appropriately added, and the temperature is 300 ° C. or lower, preferably 20 ° C. or less.
The ultrafine tin oxide particles are dried and separated together with the compound added at a temperature of 0 ° C. or lower and further at 150 ° C. or lower and redispersed in water or water mixed with another solvent.

The tin compound used in the method for producing from the decomposition reaction of the tin compound soluble in the solvent in the solvent includes K
Compounds containing oxo anions such as ₂ SnO ₃ .3H ₂ O, water-soluble halides such as SnCl ₄ , R ′ ₂ SnR
_2, R ₃ Sn _X, having a structure of _{R 2 SnX 2 (CH 3)} 3 S
nCl · (pyridine), (C ₄ H ₉ ) ₂ Sn (OCC
₂ H ₅₎ Organic tin compounds such as _2, Sn (SO ₄₎ may be mentioned ₂ · 2H ₂ oxo salts O and the like.

After a tin compound soluble in these solvents is dissolved in the solvent, a tin oxide sol is produced by a physical method such as heating and pressurizing, or a chemical method such as oxidation, reduction and hydrolysis. Alternatively, a tin oxide sol is produced via an intermediate. For example, Japanese Patent Publication No. 35-6616 discloses that SnCl ₄
Dissolve in double volume of distilled water to precipitate stannic hydroxide, then add aqueous ammonia to make it weakly alkaline, dissolve the precipitate, and heat until ammonia odor disappears to produce colloidal tin oxide sol. A method is described. As the solvent, in addition to water, methanol, ethanol, alcohol solvents such as isopropanol, tetrahydrofuran, dioxane, ether solvents such as diethyl ether, hexane, aliphatic organic solvents such as heptane, benzene, aromatic organic solvents such as pyridine, Various solvents can be used depending on the tin compound, but water and alcohols are preferred. According to this method, it is possible to add a compound containing an element other than the tin compound soluble in the solvent during the production, for example, introducing a fluorine-containing compound or a metal compound capable of taking a trivalent or pentavalent coordination number. it can.

As the fluorine-containing compound soluble in a solvent,
Either ionic fluoride or covalent fluoride may be used, and K ₂ TiF ₆ , HF, KHF ₂ Sb, F ₃ MoF ₆
Compounds that generate fluoro complex anions such as metal fluorides such as NH ₄ MnF ₃ and NH ₄ BiF ₄ , BrF ₃ , SF ₄ , etc.
Inorganic molecular fluoride such as SF ₆ , CF ₃ I, CF ₃ OO
Organic fluorine compounds such as H and P (CF ₃ ) ₃ can be mentioned. When the solvent is water, a combination of a fluorine-containing compound and a non-volatile acid is also used, such as a combination of CaF ₂ and sulfuric acid. be able to.

Examples of the metal compound which can take a trivalent or pentavalent coordination number soluble in a solvent include Al, Ca, In, and Tl.
Or a group V element such as P, As, Sb, Bi, etc. Nb, V, which can take a trivalent or pentavalent coordination number
A group of compounds containing a transition metal such as Ti, Cr, Mo, Fe, Co, and Ni.

[0030] The content of the metal oxide of the present invention contained in the heating member, 5 to 500 mg / m ² is preferably particularly preferably 10 to 350 mg / m ^2. The ratio of the amounts of the conductive oxide and the binder (PFA, PTFE) is 1/3
00-100 / 1 is preferred, and more preferably 10 vo
1% or more. In a state where 10 vol% or more is added,
It is known that percolation transition occurs when conductive particles are dispersed in an insulating matrix, and the conductivity of a layer containing the conductive particles changes significantly.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) First Embodiment A first embodiment of the present invention will be described with reference to FIG.

The fixing device has a heat fixing roller 12 provided with a heat source 11 on the inside, and a pressure roller 13 pressed against the heat fixing roller 12.
Reference numerals 2 and 13 are provided via a recording material conveyance path.

The fixing roller 12 has sliding bearings disposed at both ends thereof, and is rotatably mounted on the fixing unit frame. Further, a driving gear is fixed to one end of the fixing roller 12, and is driven to rotate in the direction of arrow a in FIG. With the rotation of the heat fixing roller 12, the pressure roller 1
3 is driven to rotate. The pressure roller 13 is the heat fixing roller 1
The nip portion 15 that presses and conveys the recording material paper is formed by pressing the recording material 2 against the recording material 2.

The heat-fixing roller 12 comprises a base 16 formed of a hollow metal tube and a release layer 17 formed thereon. In the heat fixing roller 12, a heat source 11 is provided substantially on the central axis of the hollow metal tube, and the surface of the heat fixing roller 12 has a temperature suitable for fixing (for example, 150 to 200 ° C.).
The heat fixing roller 12 is heated so that

The base 16 is made of an aluminum alloy tube, a stainless alloy tube, a carbon alloy tube or the like, and the heat source 11 is made of a halogen lamp or the like. Further, the sliding bearing and the drive gear are made of heat-resistant and highly slippery engineering plastic.

On the surface of the substrate 16, a release layer 17 having good release properties is formed.

The pressure roller 13 includes a shaft core 19 and the shaft core 1.
9 has a silicone rubber layer 20 having mold release properties and heat resistance formed on the peripheral surface of the same.

A recording material 14 having a toner image formed by an electrophotographic process is conveyed as shown by an arrow b in FIG. 1 and is sent toward a nip 15 between the heat fixing roller 12 and the pressure roller 13. . The recording material 14 passes through the nip portion under heat and pressure by the heat fixing roller 12 and the pressure roller 13. As a result, the unfixed toner image 21 is fixed on the recording material 14. The recording material 14 that has passed through the nip portion 15 is separated from the surface of the heat fixing roller 12 by the curvature separating action due to the strength of its own stiffness and the separating action of the separation guide 21, conveyed, and discharged out of the fixing device. You.

(2) Second Embodiment A fixing device according to a second embodiment is composed of a heating unit and a pressure roller 34. The heating unit includes a PFA or a polyimide film substrate in which a conductive material is dispersed. It is composed of an endless heating film 31 having a release layer made of PTFE, a ceramic heater 33 and a film guide 32.
The fixing device is driven by a pressure roller 34, and the recording material 30 and the heating film 31 are separated from the shaft core 35 and the silicone rubber layer 3.
6 is driven by the pressure roller 34. The heater 33 is formed by printing a heating paste on a ceramic substrate, and generates heat by supplying an AC current of which power is controlled to the heating paste. Glass is coated on the heating pattern to ensure protection and insulation.

The heating film 31 is driven by the pressure roller 34, slides with respect to the ceramic heater 33 and moves as indicated by an arrow a, and moves the nip portion 37 as indicated by an arrow b. The upper toner image is fixed.

[0041]

EXAMPLES <Example 1> (1) Synthesis of tin oxide sol 65 g of stannic chloride hydrate was mixed with a water / ethanol mixed solution 20
The solution was dissolved in 00 cc to obtain a homogeneous solution. Next, the coprecipitate produced by boiling this is taken out by decantation and washed with distilled water many times. After confirming that there is no reaction of chloride ion by dropping silver nitrate into the distilled water from which the precipitate has been washed, distilled water is added to the washed precipitate to reduce the total amount to 2%.
000cc. Furthermore, 40cc of 30% ammonia water
In addition, the mixture was heated in an aqueous solution and concentrated to obtain a colloidal gel dispersion having a solid content of 8%.

(2) Production of fixing film 1) Thickness of 50 μm, length when unfolded is 75.36
A conductive primer layer is provided on an endless polyimide film having a thickness of 1 mm. The role of this layer is to prevent a potential that induces an offset from reaching the film surface, and to ensure adhesion between the polyimide and the release layer. By exposing the conductive layer at the end of the film and connecting it to the ground, the potential of the conductive layer is reduced to 0 V and the potential of the film is stabilized. A solution in which 25 parts by weight of carbon black was added to and dispersed in 100 parts by weight of the silicon rubber solution was uniformly spray-coated, and then air-dried for 30 minutes to provide a conductive primer layer having a thickness of 4 μm.

2) A release layer is provided on the conductive primer layer.

An aqueous dispersion having the following composition was prepared, applied by a dipping method, dried, and heated at 380 ° C. for 20 minutes.
A μm release layer was formed.

PTFE particles 70 parts by weight PFA particles 30 parts by weight Gel dispersion of (1) 50 parts by weight The surface resistance of the finished fixing film is 1 × 10 ¹⁰ Ω /.
cm ² .

Comparative Example (1) An aqueous dispersion having the following composition was prepared, applied by an immersion method, dried, and heated at 380 ° C. for 20 minutes to form a 10 μm release layer. A fixing film was obtained in the same manner as in 2) of 1).

PTFE particles 70 parts by weight PFA particles 30 parts by weight Carbon black 1 part by weight Water 50 parts by weight The finished fixing film has a surface resistance of 1 × 10 ¹⁰ Ω /.
cm ² .

(2) An aqueous dispersion having the following composition was prepared, applied by an immersion method, dried, and heated at 380 ° C. for 20 minutes to form a 10 μm release layer. In the same manner as in (1), a fixing film was obtained.

PTFE particles 70 parts by weight PFA particles 30 parts by weight Tin oxide powder 10 parts by weight Water 50 parts by weight The surface resistance of the finished fixing film is 1 × 10 ¹⁰ Ω /.
cm ² .

The tin oxide powder was converted to X using CuKα radiation.
20 ° to 70 ° in 2θ value as measured by X-ray diffraction
A sharp scattering peak having an apex was observed. The average particle size of the crystallites determined based on the measurement results was 41.5.
In nm, it was a typical rutile crystal.

(4) Performance Comparison The above fixing film was set on a laser printer,
The following results were obtained when one sheet was printed.

[0052] Further, when a durability test of 5000 prints was performed, no offset was generated in the example, but the comparative example (1)
In the example, an offset, which is considered to be caused by peeling of the conductive agent, occurred over the entire fixing film.

[0053]

According to the present invention, since the metal oxide as the conductive material is uniformly dispersed in the release layer of the heating member, good conductivity is obtained, there is no micro-resistance unevenness, and the electrostatic offset. Is prevented from occurring.

Further, since the metal oxide serving as the conductive material is well dispersed, the metal oxide is firmly bound to the binder resin and does not cause bleed-out or peeling of the conductive material. Obtainable. Further, when the release layer of the present invention is formed on an elastic layer such as a silicon rubber layer, it has excellent barrier properties against bleeding from the lower elastic layer, and image stains due to bleed from the elastic layer and the like. Contamination of the recording material is prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 12 Heat fixing roller 17 Release layer 31 Heat film

Claims (5)

[Claims] 1. A fixing device having a heating member that contacts a recording material having a toner image to heat the toner image and fixes the toner image on the recording material, wherein the heating member has an average particle diameter of 1 to 100 nm. A fixing device comprising a high quality conductive metal oxide. 2. A fixing device having a heating member that contacts a recording material having a toner image, heats the toner image, and fixes the toner image on the recording material. A mold layer and a substrate supporting the release layer, wherein the release layer is formed by applying a composition containing a conductive metal oxide sol dispersed in a colloidal state to the substrate. A fixing device, which is a layer. 3. Contacting a recording material carrying a toner image,
In a method of manufacturing a fixing device having a heating member for heating a toner image and fixing the toner image on a recording material, the method comprises applying a composition containing a sol of a conductive metal oxide dispersed in a colloidal state to a substrate. A method for manufacturing a fixing device, comprising forming a member. 4. The fixing device according to claim 1, wherein the conductive metal oxide is SnO ₂ . 5. The method according to claim 3, wherein the conductive metal oxide is SnO ₂ .