JP2000305396A - Fluororesin-coated elastic pressure roller, and heat fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pressure roller free from toner contamination due to the sticking of paper dust even under intermittent operating conditions at a low temperature and a low humidity, to obtain a heat fixing device having high reliability even in the long-term use of the pressure roller and to prevent the toner contamination of the pressure roller even when calcium carbonate- containing paper is supplied. SOLUTION: When at least an elastomeric layer 12, an adhesive layer 13 and a fluororesin releasing layer 14 are successively laminated on a core metal 11 to obtain a fluororesin coated elastic pressure roller, <=50 deg. rubber microhardness, <=3 μm surface roughness and >=105 deg. contact angle to water are provided to the surface of the roller. In the case of >=105 deg. contact angle of the surface of the pressure roller to water, the surface energy of the pressure roller can be set small and the sticking of paper dust and a toner is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure roller and a heat fixing device used in an electrophotographic image forming apparatus such as a copying machine and an LBP. More specifically, the present invention relates to a roller for nipping a recording material to convey the recording material, and is particularly used for permanently fixing toner on a recording material in a recording method such as an electrophotographic method or an electrostatic recording method. The present invention relates to a pressure roller used in a heat fixing system.

[0002]

2. Description of the Related Art Conventionally, many electrophotographic copying machines, printers, and the like employ a heat roller fixing system of a contact heating type and a film heating system of an energy saving type which have good thermal efficiency and safety as fixing means. .

[0003] The heat fixing device of the heat roller fixing system basically comprises a heating roller (fixing roller) as a heating rotating body and an elastic pressure roller as a pressing rotating body pressed against the heating roller. Is rotated so that an unfixed image (toner image) is formed and held in a pressure contact nip portion (fixing nip portion) of the roller pair (transfer material sheet, electrostatic recording paper, electrofax Paper, printing paper, etc.) is passed through the press-contact nip portion while being pinched and conveyed, so that the unfixed image is permanently fixed on the surface of the recording material by the heat from the heating roller and the pressing force of the press-contact nip portion. It is to fix it.

As the elastic pressure roller used here, a roller in which an elastic layer is formed on a cylindrical or cylindrical core metal, and a fluororesin layer as a toner release layer is formed on the outer peripheral surface thereof is often used. . In order to ensure a contact area between the transfer material and the heating member, the pressure roller is required to have sufficient elasticity, and the elastic layer is set to be relatively thick. As the material of the elastic layer, silicone rubber is often used from the viewpoint of heat resistance.

Further, a fixing device of a film heating type is disclosed in, for example, JP-A-63-313182 and JP-A-2-15.
Nos. 7878, 4-44075-44083, and 4
-204980-204984, and a heat-resistant film (fixing film), which is a heating rotator, is brought into close contact with a heating element by a pressing rotator (elastic roller) and is slid and conveyed. A recording material carrying an unfixed image is introduced into a press-contact nip formed by a heating element and a pressing member while holding a fixing film, and is conveyed together with a heat-resistant film, and applied via a heat-resistant film. This is an apparatus for fixing an unfixed image as a permanent image on a recording material by heat from a heating body and a pressing force of a pressing nip portion.

In the film heating type heating apparatus, a linear heating element having a low heat capacity can be used as a heating element, and a film having a low heat capacity of a thin film can be used as a heating element. ) Is possible.

Further, in this type of fixing system, a driving roller is provided on the inner peripheral surface of the film as a driving method of the fixing film, and the driving is performed while applying tension to the film.
A method is known in which a film is loosely fitted into a film guide, and the film is driven to rotate with respect to the pressure rotating body by driving the pressure rotating body. However, in recent years, the number of parts has been reduced. In many cases, the latter method of driving the rotating body for pressurization is adopted.

As the elastic pressure roller used here, a silicone rubber elastic layer or a silicone sponge layer is formed on a cylindrical or cylindrical cored bar, and the outer peripheral surface thereof is used as a toner release layer directly or through an adhesive layer. Of which a fluororesin layer is formed is widely used. As the fluororesin layer, those formed by coating a fluororesin tube, and those formed through a process of applying and firing a fluororesin-based paint have been put to practical use. In order to ensure a contact area between the transfer material and the heating member, the pressure roller is required to have sufficient elasticity, and the elastic layer is set to be relatively thick.

In recent years, there has been a strong demand not only for the above-described heat-fixing device driven by a pressure roller but also for a heat roller-fixing device or a heat-fixing device driven by a fixing film. There is a demand for miniaturization. Further, in order to save power, heat fixing devices that do not perform standby temperature control by increasing heating efficiency are increasing.

In order to satisfy the above-mentioned requirements in such an apparatus, a fixing roller and a pressure roller having a relatively small pressure and a small diameter must be used, and the conveying speed of the recording material of the image forming apparatus is high. In this case, in order to supply a sufficient amount of heat to the recording material, it is necessary to increase the pressure nip width between the fixing roller or the fixing film and the pressure roller at low pressure. Attempts have been made to develop pressurized rollers.

For example, in Japanese Patent Application Laid-Open No. Hei 7-271233, in order to provide a fixing roller having a low hardness, hollow holes continuous in the length direction are provided in a silicone rubber layer formed of liquid silicone. A pressure roller for fixing, and further, when a fluororesin surface layer is provided on the silicone rubber layer, it is proposed that the surface hardness measured by an Asker-C type hardness meter (1 kgf) is 60 degrees or less. .

In Japanese Patent Application Laid-Open No. Hei 7-271233, an elastic layer of a pressure roller is formed of a porous silicone rubber and has a hardness of 35 to 50 ° (Asker-C) and a sponge layer coated on the sponge layer. There has been proposed a pressure roller formed of a PFA tube and having a roller hardness of 45 to 60 ° (Asker-C) and capable of preventing occurrence of paper wrinkles and having good fixability.

The above-mentioned JP-A-63-313182 and JP-A-2-1577878 disclose at least a fixedly supported heater (heater) and a fixing device which is conveyed while being pressed against the heater. A heater unit comprising a heat-resistant cylindrical film (hereinafter, referred to as a film);
An unfixed image (toner image) formed and carried on the surface of the recording material by applying heat of the heating element to the recording material via a film, and ) Is proposed and put to practical use.

An example of such a heat fixing device is shown in FIG. 3 and will be described below. In FIG. 3, reference numeral 101 denotes a cylindrical film, a polyimide film having a thickness of 40 to 60 μm is used as a base layer, and PFA and PFA having a thickness of 40 to 60 μm are formed on the outer peripheral surface (the surface that comes into contact with the recording material and the toner image). A release layer in which PTFE is dispersed is formed therein.

Reference numeral 102 denotes a heater as a heating element, which is a ceramic substrate having an insulating property, a heat resistance, and a low heat capacity whose longitudinal direction is perpendicular to the conveying direction of the recording material P, and which is printed on the surface thereof along the longitudinal direction. And a temperature sensing element 103 (such as a thermistor) provided in contact with the ceramic substrate on the side opposite to the exposed surface of the resistance heater on the ceramic substrate.
Is a basic configuration.

The heater 102 is insulated and fixedly supported so that the heating element is exposed to a film guide 104 (heater stay) having a semicircular trough-shaped cross section. Also,
The temperature control of the heater 102 is performed by controlling the energization of a resistance heating element (not shown) from a power supply (not shown) by a control unit (not shown) according to the output of the temperature detecting element 103. .

Reference numeral 108 denotes the heater 102 and the thermistor 10
3. An inverted U-shaped reinforcing sheet metal provided so that the heater unit including the film guide 104 and the like is not deformed when pressed by the pressing roller 105. The film 101 has an inner peripheral diameter of at least the reinforcing sheet metal 1.
08 is larger than the length of the film guide 104.

The pressure roller 105 is composed of a metal core 106 and a heat-resistant rubber 107, and is pressed against the heater 102 by a pressure means (not shown) at a total pressure of 5 to 15 kgf. Further, the pressure roller 105 is rotationally driven (counterclockwise by an arrow) by a drive system (not shown). As a result, the film 101 slides in close contact with the surface of the resistance heating element of the heater 102, and rotates around the film guide 104 in the clockwise direction indicated by the arrow. At this time, the heater 102 and the film 101
In order to reduce the sliding friction of the inner surface of the above, heat-resistant grease is interposed between the two.

With the above configuration, the recording material P is guided between the film 101 and the pressure roller 105 and passes through the nip portion N, so that the toner image on the recording material is heated and fixed on the recording material. .

The above-mentioned heat fixing device can reduce the heat capacity of the heater portion to several tenths and can use a heat-generating element whose temperature rises quickly, as compared with a conventional heat roller fixing device. Since it is possible, the time required for the heated portion to reach a temperature at which fixing can be performed can be set to several seconds to several tens of seconds. Therefore, so-called on-demand fixing, which has been difficult to achieve in the heat roller fixing device, becomes possible.

In this heat fixing device, the heater 102
Thermistor 1 on the side opposite to the side where the resistance heating element is printed
When the heater 102 abnormally rises in temperature, the control means that has received the information from the thermistor 103 controls a switching element (not shown) to cut off the power supply.

However, when the above-mentioned conventional pressure roller is used in the heat fixing device and is operated under intermittent operation conditions in a low-temperature environment, disturbance of a fixed image due to toner contamination on the surface of the pressure roller causes Paper wrinkles, paper wrapping around the pressure roller, etc. may occur more often.

Regarding toner contamination of the pressure roller, a phenomenon was first observed in which paper powder of transfer paper adhered to the roller surface, and this became a nucleus to accumulate toner transferred from the fixing film side. Further, it was confirmed that the adhesion of the paper dust was more remarkable when the pressure roller was operated at a lower surface temperature.

In a power saving heat fixing device which does not have a standby temperature control function, since the pressure roller surface comes into contact with the transfer paper before the surface thereof is warmed, the adhesion of paper powder is also likely to occur.

This phenomenon is considered as follows.

The paper dust adheres to the toner adhered to the surface of the pressure roller. At this time, if the surface of the pressure roller is sufficiently heated, the toner is softened.
It easily adheres to the transferred transfer paper and is removed from the surface of the pressure roller. At this time, the paper dust is also removed from the surface of the pressure roller together with the toner. However, if the pressure roller surface is not sufficiently heated, such removal of the paper dust is unlikely to occur.

Further, as described above, especially in a heat fixing device of a film heating type, there is a demand for power saving and shortening of a wait time (improvement of quick start property).
The heat capacity of the heating member (fixing film) is so small that the pressure roller is difficult to warm up. Also, due to the demand for miniaturization of the image forming apparatus, a fixing film having a relatively low pressure, a small diameter, A pressure roller must be used, and the configuration is strict with respect to the electrostatic offset property. Particularly under intermittent operation conditions in a low temperature environment, the amount of toner offset to the fixing film tends to increase.

This phenomenon is considered as follows.

The toner adhering to the transfer paper is electrostatically attracted to the fixing film surface. This electrostatic attraction force is caused, for example, by the transfer of the electric charge of the transfer paper sucking the toner to the fixing film surface. When the surface of the pressure roller is sufficiently heated, in addition to the heat from the fixing film, the heat from the pressure roller heats the toner through the transfer paper. Therefore, the toner is sufficiently softened, and is not transferred to the fixing film surface due to its adhesive strength. However, when the pressure roller surface is not sufficiently heated, the heat from the pressure roller side is small, and the toner is not sufficiently softened, so that the adhesive force to the transfer paper is small. A part of the toner is offset (electrostatic offset) on the fixing film surface.

The toner offset to the fixing film is
In some cases, the toner image is transferred and accumulated in the pressure roller, resulting in disorder of the fixed image, paper wrinkling, and paper wrapping around the pressure roller.

The conventional pressure roller is concerned with lowering the hardness of the entire roller for the purpose of securing the fixing property and the transportability, and is not a solution to the phenomenon of adhering paper powder on the roller surface.

Also, in many conventional fixing devices,
Many of them do not have a cleaning device for the purpose of cost reduction and the like. Further, in recent years, the reduction in toner particle size aimed at higher image quality has made cleaning by a cleaning unit difficult, and this tendency has been spurred.
On the other hand, in order to preserve paper for a long time, the transition from acidic paper to neutral paper has progressed, and calcium carbonate has been increasingly used as a paper filler. Further, recycled paper and the like containing a plurality of inorganic materials such as calcium carbonate and talc as a filler are increasing.

However, such a filler has an adverse effect of adhering to a pressure roller, a fixing roller, a fixing film, etc., thereby deteriorating the releasability, and as a result, toner is deposited on the surface of the pressure roller. There is a problem that a stain is formed on an image or a paper is wrapped around to form a jam.

[0034]

SUMMARY OF THE INVENTION The present invention relates to a pressure roller used for a heat fixing device of an electrophotographic image forming apparatus, which is free from surface contamination for a long time even when it is operated under intermittent operation conditions in a low temperature environment. To provide a pressure roller having a stable releasing property, that is, a durable use property and an appropriate grip property, and always having a good member conveying property, and a highly reliable film heating type fixing device for a long term use. It is intended for.

Another object of the present invention is to provide a pressurizing device which satisfies the original fixing characteristics and durability, prevents toner from sticking to the surface of the pressurizing roller, and prevents problems such as image stains and jams. A roller and a heat fixing device are provided.

[0036]

SUMMARY OF THE INVENTION The present invention provides a fluororesin-coated elastic pressure roller in which at least a rubber elastic layer, an adhesive layer, and a fluororesin release layer are sequentially laminated on a cored bar. Characterized by a micro rubber hardness of 50 ° or less, a contact angle with water of 105 ° or more, and a surface roughness Rz (ten-point average roughness) of 3.0 μm or less Rollers are provided.

When the surface of the pressure roller has low hardness and high flexibility, expansion and contraction of the roller in the circumferential direction in and around the nip repeatedly occur, making it difficult for paper powder to adhere, and once adhered by some action such as static electricity. It is considered that the paper powder is also sequentially dropped. Therefore, it is possible to prevent toner contamination on the surface of the pressure roller due to the adhesion of paper powder. If the micro rubber hardness of the pressure roller surface exceeds 50 °, the above effect may not be expected due to lack of sufficient elasticity in the roller circumferential direction in and around the nip of the pressure roller surface.

The contact angle of the pressure roller surface with water is set to 1
By setting the angle to 05 ° or more, the surface energy of the pressure roller can be set small, and the adhesion of paper dust and toner can be reduced.

The surface roughness of the pressure roller is 3.0 μm.
By setting m (Rz), it is possible to prevent the toner from entering the concave portion on the roller surface and becoming a core of further toner and paper powder.

It is an object of the present invention to provide a pressure roller having good transportability without toner adhesion by combining these physical properties.

The micro rubber hardness of the surface of the pressure roller in the present invention is preferably 10 ° or more from the viewpoint of abrasion resistance.

The contact angle of the surface of the fluororesin-coated elastic pressure roller with water is preferably 105 ° to 130 °.

It is preferable that the surface roughness Rz (ten-point average roughness) of the fluororesin-coated elastic pressure roller is 0.1 to 3.0 μm.

Further, it is preferable that the elastic layer of the fluororesin-coated elastic pressure roller is made of silicone rubber having a JIS-A hardness of 5 ° to 25 °.

Preferably, the thickness of the adhesive layer of the fluororesin-coated elastic pressure roller is 5 to 18 μm and the thickness of the surface fluororesin is 1 to 10 μm.

Further, the adhesive layer is a rubber elastic body containing a fluororesin powder, and its material has a JIS-A rubber hardness of 30.
It is preferable that the angle is from 75 ° to 75 °.

The present invention provides a heat and pressure fixing device including the above-mentioned fluororesin-coated elastic pressure roller.

Further, the present invention relates to a heat fixing apparatus of a film heating type of an electrophotographic image forming apparatus comprising a fixing film having a fluororesin release layer on the surface and an elastic pressure roller coated with a fluororesin, The surface roughness Rz (ten-point average roughness) of the surface of the resin release layer is 5 μm or less, and the fluororesin-coated elastic pressure roller has at least a rubber elastic layer, an adhesive layer, and a fluororesin release layer on a cored bar. Are sequentially laminated elastic rollers having a micro rubber hardness of 50 ° or less on the roller surface and a contact angle with water of 1
The surface roughness Rz (ten-point average roughness) of 3.0 ° or more is 3.0
An object of the present invention is to provide a heat fixing device characterized by having a thickness of not more than μm.

The micro rubber hardness of the surface of the pressure roller referred to in the present invention is measured by a method according to "Micro Test" of JIS-K-6253, and reflects the hardness relatively near the surface of the pressure roller. Hardness. Spring type rubber hardness tester (Durometer) Micro rubber hardness tester (commercial name,
Microhardness tester MD-1, manufactured by Kobunshi Keiki Co., Ltd.).

The contact angle was measured using a contact angle meter (trade name: contact angle meter CA-X, manufactured by Kyowa Interface Science Co., Ltd.).

The hardness of the pressure roller surface is determined by a combination of the material hardness of the adhesive layer, the thickness of the adhesive layer, and the thickness of the fluororesin release layer. The material hardness of the adhesive layer is not particularly limited as long as it is higher than the material hardness of the elastic layer. When the material hardness of the elastic layer is less than or equal to the material hardness, the difference in hardness between the fluororesin release layer and the adhesive layer increases, and stress concentration occurs at the interface due to roller deformation in the nip, causing problems in adhesive durability. There is. The thickness of the adhesive layer is usually 3 to 35 μm, and the thickness of the fluororesin release layer is usually selected in the range of 1 to 20 μm so that the micro rubber hardness of the pressure roller surface is 50 ° or less.

In the present invention, the contact angle of the pressure roller surface is preferably 130 ° or less, or the surface roughness Rz (ten-point average roughness) is preferably 0.1 μm or more. This is because it takes a long time for the smoothing process to make the contact angle larger than 130 ° by smoothing the surface of the pressure roller to a level smaller than 0.1 μm.

Rz is the surface roughness specified in JIS-B0601. That is, Rz is extracted from the roughness curve by a reference length (0.8 mm) in the direction of the average line, and is measured in the direction of the vertical magnification from the average line of the extracted portion, from the highest peak to the fifth peak. Of the absolute value of the altitude (Yp) and the average of the absolute values of the altitudes (Yv) of the lowest to fifth valleys are obtained, and this value is expressed in micrometers (μm). Things.

[0054]

[Outside 1] The surface roughness was measured by Kosaka Laboratory SE-340.
0 It was measured using a surface roughness measuring instrument (trade name).

The material of the elastic layer is preferably silicone rubber in terms of heat resistance and setability.
When IS-A) is less than 5 °, the mechanical strength is insufficient, and a problem may occur in durability. If the hardness (JIS-A) of the silicone rubber is less than 25 °, the roller can be sufficiently deformed at the nip portion and the surface of the pressure roller can be greatly expanded and contracted, which is effective in preventing the adhesion of paper powder.

In the fluororesin-coated elastic pressure roller of the present invention, the thickness of the surface fluororesin is preferably 1 to 10 μm and the thickness of the adhesive layer is preferably 5 to 18 μm.

Although the elasticity of the surface of the pressure roller depends on the hardness of the adhesive layer, the thickness of the surface fluororesin is 1 to 10 μm.
m and the thickness of the adhesive layer is 5 to 18 μm, it is possible to secure the elasticity of the surface of the pressure roller for preventing the adhesion of paper dust even when the hardness of the material of the adhesive layer exceeds 90 °.

In the fluororesin-coated elastic pressure roller of the present invention, the adhesive layer is a rubber elastic body containing a fluororesin powder, and the JIS-A rubber hardness of the material is 30 ° to 75 °.
It is preferred that

The fluororesin powder is a component involved in adhesion to the fluororesin release layer, and is made of PTFE, PFA, FEP.
At least one kind is selected from the fluororesins. From the viewpoint of heat resistance and adhesiveness, FEP is most preferable, and the compounding amount is not particularly limited as long as the adhesiveness is ensured.
The range of 70 to 130 parts by weight per 100 parts by weight of the rubber component is preferably selected.

J of rubber elastic material containing fluororesin powder
If the IS-A rubber hardness does not exceed 75 °, the elasticity of the surface of the pressure roller for preventing the adhesion of paper dust can be ensured. On the other hand, when the angle is less than 30 °, the hardness difference between the fluororesin release layer and the adhesive layer becomes large, and stress concentration occurs at the interface due to roller deformation of the nip portion, which may cause a problem in adhesive durability.

FIG. 1 is a schematic sectional view of a fluororesin-coated elastic pressure roller of the present invention.

Reference numeral 11 denotes a core made of iron, aluminum, or the like.
An elastic layer 12 made of a silicone rubber material having a JIS-A hardness of 5 ° to 25 °, an adhesive layer 13, and a fluororesin layer 14 such as PTFE, PFA, FEP, and the like as a release layer are sequentially formed on 1.

FIG. 2 is a schematic sectional view of a film heating type fixing device according to the present invention.

In FIG. 2, reference numeral 20 denotes a heat-resistant film (fixing film) in the form of an endless belt, which is fitted around a semicircular film guide member (stay) 23 with a margin in the circumferential length. ing.

The fixing film 20 has a total film thickness of 10 in order to reduce the heat capacity and improve the quick start property.
0 μm or less, preferably in the range of 60 to 20 μm.
Polytetrafluoroethylene (PTFE) and tetrafluoroethylene with heat resistance, release property, strength, durability, etc.
Perfluoroalkyl vinyl ether copolymer (PF
A), a single-layer film such as polyphenylene sulfide (PPS), or a film such as polyimide, polyamide imide, polyetheretherketone (PEEK), or polyethersulfone (PES) on a fluorine-based primer through PTFE, PFA And a composite layer film coated with a fluororesin such as tetrafluoroethylene / hexafluoropropylene copolymer (FEP) as a release layer. The release layer having a surface roughness of Rz 5 μm or less is used.

Reference numeral 21 denotes a pressure roller of the present invention, which has an elastic layer, an adhesive layer, and a release layer made of fluororesin formed on a core metal such as iron or aluminum. The micro rubber hardness on the surface of the pressure roller 21 is 50 ° or less.

In FIG. 2, the fixing film 20 is brought into close contact with the surface of the heating body 22 in the clockwise direction indicated by an arrow at least during execution of image fixing by sliding of the pressure roller 21 so that the fixing film 20 slides on the heating body surface for a predetermined period. The rotation speed is substantially the same as the speed of transporting the transfer material P carrying the unfixed toner image T transported from the image forming unit (not shown), and without wrinkles.

The heating element 22 includes an energizing heating element (resistance heating element) 22a as a heat source that generates heat by supplying power.
The temperature rises due to the heat generated by the energizing heating element 22a.

The heating element 22 is heated by the power supply to the energizing heating element 22a, and in a state where the fixing film 20 is driven to rotate, the heating element 22 is connected to the heating element 22 by the elastic force generated by the deformation of the elastic layer of the pressing roller 21. The transfer material P is applied to the pressure contact nip N (fixing nip) formed between
Is introduced, the transfer material P comes into close contact with the film 20 and the fixing nip N
Pass through.

In the process of passing the transfer material P through the fixing nip,
Heat energy is applied to the transfer material P from the heating body 22 via the film 20, the unfixed toner image T is heat-fused and fixed on the transfer material P, and the transfer material P is separated and discharged from the film 20 after passing through the fixing nip. Is done.

[0071]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A pressure roller having the structure shown in FIG. 1 was manufactured.

A silicone rubber having a rubber length of 225 mm, a rubber thickness of 2.5 mm, and an outer diameter of 20 mm (trade name: DY35-561A / B, Toray
An elastic layer (manufactured by Dow Corning Silicon) was formed. After a primer treatment on this elastic layer, the following (Table 1) Example 1-1
接着 1 to 4 were sequentially formed with an adhesive layer made of a mixture of a fluororubber and a fluororesin, and a fluororesin layer as a release layer. The adhesive layer made of a mixture of fluororubber and fluororesin is laminated by applying, drying and curing a MIBK solution of a kneaded product having the following composition A. Formula A has a cured hardness of 90
°.

[Compound A] Fluorine rubber raw rubber (trade name: G501, manufactured by Daikin Industries, Ltd.) 100 (parts by weight) MT carbon (trade name: Thermax N-990, manufactured by CANCARB) 5 Magnesium oxide (trade name: Kyowa Mag MA-) 150, manufactured by Kyowa Chemical Industry Co., Ltd.) 15 NN-dicinnamylidene-1,6-hexadiamine 6 FEP powder (trade name: 532-8000, manufactured by DuPont) The surface layer is a FEP dispersion (trade name: ND1, manufactured by Daikin Industries, Ltd.) ) Was formed by coating, drying and firing.

The surface roughness (Rz) of the pressure roller thus manufactured was 5 μm. Therefore, as a surface smoothing treatment, a pressure roller is inserted into a polyimide tube whose inner diameter is substantially the same as the outer diameter of the pressure roller and the inner wall is smooth, and heat treatment is performed at 270 ° C. for 2 minutes. The surface roughness of the surface layer was reduced to 1 μm by pressing the surface layer of the pressure roller against the inner wall of the tube by thermal expansion of the cored bar.
The contact angle of the surface layer was 110 °.

Comparative Example 1 The pressure roller of Comparative Examples 1-1 to 1-3 was the same as in Examples 1-1 to 1-4 except that the thicknesses of the adhesive layer and the surface layer were as shown in Table 1. It was created.

The elastic layer is made of silicone rubber (trade name:
DY35-560A / B, manufactured by Dow Corning Toray Silicone Co., Ltd.) and a pressure roller made in the same manner as in Example 1-2, except that a PFA tube was put on the adhesive layer as a surface layer. Was set as Comparative Example 1-4. Note that F
The surface of the EP tube was not subjected to a surface smoothing treatment. The surface roughness (Rz) of Comparative Example 1-4 was 0.8 μm,
The contact angle is 108 °.

[0077]

[Table 1] Example 2 An adhesive layer made of a mixture of fluororubber and fluororesin having a thickness shown in Table 2 after a primer treatment on a silicone rubber elastic layer formed in the same manner as in Example 1, and a fluororesin layer as a surface layer were sequentially formed. Formed. The adhesive layer was formed by applying, drying and curing a MIBK solution of a kneaded product having the following formulation B for Example 2-1 and the following formulation C for Example 2-2. Formulation B, C after curing (JIS-A)
The hardness was 73 ° and 70 °, respectively.

[Compound B] Fluoro rubber raw rubber (trade name: G501) 100 (parts by weight) MT carbon (trade name: Thermax N-990) 0 Magnesium oxide (trade name: Kwamag MA-150) 15 NN-dicinnamylidene-1 , 6-Hexadiamine 1.5 FEP powder (trade name: 332-8000) 100 [Formulation C] Fluoro rubber raw rubber (trade name: G621, manufactured by Daikin Industries, Ltd.) 100 (parts by weight) (product with polyol crosslinking agent) MT Carbon (trade name: Thermax N-990) 0 Calcium hydroxide (trade name: CALDIC-2000, manufactured by Omi Chemical Industry Co., Ltd.) 2 Magnesium oxide (trade name: Kuwamag MA-150) 3 FEP powder (trade name: 332-8000) 100) In both Examples 2-1 and 2-2, the fluororesin of the surface layer Is, PFA dispersion (trade name: AD2, manufactured by Daikin Industries, Ltd.) was coated, dried, formed by the firing and surface smoothing treatment.

The surface roughness before the surface smoothing treatment was 7 μm.
m, a surface smoothing treatment was performed at 300 ° C. for 3 minutes.

The surface roughness (Rz) of the surface layer is 1.0 μm, and the contact angle is 105 °.

[0081]

[Table 2] The pressure rollers manufactured in Examples and Comparative Examples were applied to the heat fixing device of FIG. 2 to evaluate the performance.

The fixing film used in the experiment had a thickness of 40 μm.
m, 5 mm on a seamless polyimide film with an outer diameter of 25 mm
A fluororesin dispersion (a blend of PTFE and PFA in a ratio of 50/50) was applied and fired as a release layer via a fluorine-based primer having a thickness of μm, and then cut to a length of 230 mm. The surface roughness Rz of the surface of the fluororesin layer is finished to 4.5 μm.

Each roller of Example 1, Example 2, and Comparative Example was incorporated in the above-mentioned heat fixing device, and output by a laser beam printer (trade name: Laser Shot LBP320, manufactured by Canon). A paper passing test was performed using A4 size paper with an unfixed image. Pressing roller at a peripheral speed of 90 mm
/ Sec, and set to supply 900 W of electric power to the heating element only when paper is passed. Under a low-temperature and low-humidity environment (15 ° C., 10%) where electrostatic offset easily occurs, intermittent operation conditions (two sheets 5,000 sheets of paper were each tested. During the test, the surface temperature of the pressure roller did not exceed 80 ° C.

In Examples 1-1 to 1-3, there was no trouble relating to the transportability during the test, and the adhesion of paper powder on the surface of the pressure roller after the test was slight, and no toner stain was observed. . In Examples 1-4 and Examples 2-1 and 2-2, there was no trouble regarding the transportability during the test, and no adhesion of paper powder and toner stain on the surface of the pressure roller after the completion was observed.

In Comparative Examples 1-1 to 1-4, a considerable amount of toner stain was observed on the surface of the pressure roller after 5,000 sheets had been printed.

Example 3 Roller diameter 20 mm, rubber surface length 230 mm, rubber thickness 3.5 mm, aluminum core material, aluminum core length 260 mm, silicone rubber as a rubber material (trade name: DY35-561A / B) , And an adhesive GLP-103 (trade name) manufactured by Daikin Industries, Ltd. is applied thereon to a thickness of 3 μm, and the Daikin Industries, Ltd.
ND1 manufactured by Daikin Industries, Ltd. as FEP for 100 parts by weight of fluorine latex GLS213 (trade name) manufactured by Daikin Industries, Ltd.
A mixture of 5 parts by weight (trade name) and 5 parts by weight of a curing agent is applied and baked to form a layer of about 20 μm. In addition, Daikin Industries, Ltd.
ND1 manufactured is applied and fired to form a layer of about 5 μm.
Next, a surface smoothing treatment was performed in the same manner as in Example 1.
As a result of measuring the micro surface hardness of the roller thus formed, a measured value of the surface hardness of 43 ° was obtained. The contact angle of this roller with water is 110 °. The surface roughness (Rz) is 0.8 μm.

Comparative Example 2 Roller diameter 20 mm, rubber surface length 230 mm, rubber thickness 3.5 mm, aluminum core material, aluminum core length 260 mm, silicone rubber as a rubber material (trade name: DY35-561A / B) , And an adhesive GLP-103 manufactured by Daikin Industries, Ltd. is applied thereon, and a fluorine latex G manufactured by Daikin Industries, Ltd. is further applied thereon.
A mixture of 5 parts by weight of ND1 manufactured by Daikin Industries, Ltd. and 10 parts by weight of a curing agent as FEP to 100 parts by weight of LS213 is applied and baked so that a layer of about 30 μm is formed. Further, ND1 manufactured by Daikin Industries, Ltd. is applied thereon as an FEP and baked to form a layer of about 10 μm. Next, a surface smoothing treatment was performed in the same manner as in Example 1. The micro surface hardness of the roller thus formed is 54 °. The contact angle of this roller with water is 112 °. The surface roughness (Rz) is 0.5 μm.

Comparative Example 3 Roller diameter 20 mm, rubber surface length 230 mm, rubber thickness 3.5 mm, aluminum core material, aluminum core length 260 mm, silicone rubber as a rubber material (trade name: DY35-561A / B) , And an adhesive GLP-103 manufactured by Daikin Industries, Ltd. is applied thereon, and a fluorine latex G manufactured by Daikin Industries, Ltd. is further applied thereon.
A mixture of 5 parts by weight of ND1 manufactured by Daikin Industries, Ltd. and 5 parts by weight of a curing agent as FEP to 100 parts by weight of LS213 is applied and baked to form a layer of about 5 μm. Further, ND1 manufactured by Daikin Industries, Ltd. is applied thereon as an FEP and baked to form a layer of about 5 μm. Next, a surface smoothing treatment was performed in the same manner as in Example 1. The micro surface hardness of the roller thus formed is 39 °, and the contact angle with water is 100 °. The surface roughness (Rz) is 4.2 μm.

The pressure rollers produced in Example 3 and Comparative Examples 2 and 3 were applied to the heat fixing device shown in FIG. 3 to evaluate the performance.

Evaluation of dirt on pressure roller: The experiment was performed by Bois
e Cascade X9000 paper (basis weight 80g / m
² ) in an environment of 10 ° C./15% RH
The dirt on the pressure roller was evaluated by a method of fixing two unfixed prints output by a laser beam printer (trade name: Laser Shot LBP320) every minute. The reason for using this paper is that it contains both calcium carbonate and talc as filler. In the pressure roller of Example 3, no stain on the pressure roller and no stain on the image was generated even if the number of sheets exceeded 5,000. On the other hand, Comparative Example 2
With the pressure roller (1), a large amount of dirt was seen around 300 sheets after a little over 300 sheets, and toner particles came to adhere to the paper. Further, with the pressure roller of Comparative Example 3, a wide range of dirt was observed around 1500 sheets after the dirt began to be slightly removed from the place where the number exceeded 1000 sheets, and toner particles came to adhere to the paper.

Although the third embodiment and the comparative examples 2 and 3 have been described, the relationship between the surface hardness of the roller and the contact angle with water is shown in FIG. Here, ○ indicates that no toner stain occurs up to 5000 sheets, and △ indicates 30
In the case where the toner stain was generated on the 00 sheet, x indicates that the toner stain was generated early. As can be seen from FIG.
When the contact angle is about 105 ° or less, the toner stain resistance is poor. However, even if the contact angle is 105 ° or more, if the surface hardness is 50 ° or more, the toner stain resistance is poor. From this, it can be seen that in order to obtain a pressure roller having excellent toner stain resistance, it is necessary to have a large contact angle, that is, excellent smoothness, and a soft surface hardness.

When the surface of the pressure roller is soft, the followability to paper is improved, and the generation of paper dust and the action of rubbing the toner can be suppressed. However, when the surface hardness is reduced, the surface of the pressure roller tends to be roughened, so that toner stains easily accumulate in recesses on the surface. Therefore, by balancing the smoothness and hardness of the surface of the pressure roller, it is possible to obtain a pressure roller having excellent toner stain resistance.

FIG. 6 shows the results obtained when the surface roughness, not the contact angle with water, was measured as a parameter representing the smoothness of the pressure roller surface. ○, Δ, and × are the same as in FIG. As can be seen from FIG. 6, in the case where the smoothness is represented by the surface roughness, the range of the pressure roller having excellent toner stain resistance is as follows.
It can be seen that the surface hardness is 50 ° or less and the surface roughness Rz is 3.0 μm or less.

[0094]

As described above, in the pressure roller used in the heat fixing device of the electrophotographic image forming apparatus, even if it is operated under intermittent operation conditions in a low temperature environment, it is possible to obtain a stable surface free from contamination for a long time. It is possible to provide a pressure roller that always has good releasing properties, that is, a roller that imparts good durability and a moderate gripping property and that has good transportability of a member, and a highly reliable film heating type fixing device for long-term use. It was done.

On the other hand, when the pressure roller surface micro rubber hardness is 50 ° or less, the contact angle with water is 105 ° or more, and the pressure roller surface roughness is Rz 3.0 μm or less, paper such as calcium carbonate is obtained. It is possible to provide a pressure roller and a heat fixing device that can prevent the toner from adhering to the pressure roller, which is considered to be caused by the filler or paper powder, for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a pressure roller according to an embodiment.

FIG. 2 is a schematic cross-sectional view of a film heating type fixing device of an embodiment.

FIG. 3 is a conceptual diagram of a configuration of a conventional heat fixing device.

FIG. 4 is another example of a schematic sectional view of a pressure roller.

FIG. 5 is a diagram showing the relationship between the pressure roller surface hardness and the contact angle of the pressure roller surface with water.

FIG. 6 is a diagram illustrating a relationship between a pressure roller surface hardness and a pressure roller surface roughness.

Continuing on the front page (72) Osamu May, the inventor in Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Yuji Kitano 3-30-2, Shimomaruko 3-chome in Ota-ku, Tokyo (72) Inventor Masaaki Takahashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masato Yoshioka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Invention Person Yasumasa Otsuka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Toshihiko Ochiai 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kenji Karashima Tokyo (72) Inventor Ryo Hayakawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (9)

[Claims] 1. A fluororesin-coated elastic pressure roller in which at least a rubber elastic layer, an adhesive layer, and a fluororesin release layer are sequentially laminated on a cored bar, wherein the surface of the pressure roller has a micro rubber hardness of 50 ° or less. With a water contact angle of 105
° or more, the surface roughness Rz (ten-point average roughness) is 3.0 μm
A fluorine resin-coated elastic pressure roller characterized by the following. 2. The fluororesin-coated elastic pressure roller according to claim 1, wherein the micro-rubber hardness of the surface of the fluororesin-coated elastic pressure roller is 10 ° to 50 °. 3. The fluororesin-coated elastic pressure roller according to claim 1, wherein the contact angle of the surface of the fluororesin-coated elastic pressure roller with water is 105 ° to 130 °. 4. The fluororesin-coated elastic pressure roller according to claim 1, wherein a surface roughness Rz (ten-point average roughness) of the fluororesin-coated elastic pressure roller is 0.1 to 3.0 μm. . 5. The fluororesin-coated elastic pressure roller according to claim 1, wherein the elastic layer of the fluororesin-coated elastic pressure roller is made of silicone rubber having a JIS-A hardness of 5 ° to 25 °. 6. The fluororesin-coated elastic pressure roller has an adhesive layer having a thickness of 5 to 18 μm and a surface fluororesin having a thickness of 1 to 18.
3. The fluororesin-coated elastic pressure roller according to claim 2, wherein the thickness is from 10 to 10 [mu] m. 7. The adhesive layer is a rubber elastic body containing a fluororesin powder, and its material has a JIS-A rubber hardness of 30 ° or more.
The fluororesin-coated elastic pressure roller according to claim 5, wherein the angle is 75 °. 8. A heat and pressure fixing device comprising the pressure roller according to claim 1. 9. A heat fixing device of a film heating type of an electrophotographic image forming apparatus having a fixing film having a fluororesin release layer on the surface and a fluororesin-coated elastic pressure roller, wherein the fluororesin release layer of the fixing film is provided. The surface has a surface roughness Rz (ten-point average roughness) of 5 μm or less, and the fluororesin-coated elastic pressure roller has at least a rubber elastic layer, an adhesive layer, and a fluororesin release layer sequentially laminated on a cored bar. An elastic roller, wherein the micro rubber hardness of the roller surface is 50 ° or less and the contact angle with water is 105 ° or more,
A heat fixing device having a surface roughness Rz (ten-point average roughness) of 3.0 μm or less.