JP2005062470A - Pressure member for fixation, device and method for fixation, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure member for fixation, such that a release layer has superior heat resistance and hardly deforms even when pressed by a cleaning means such as a blade or wears off even when rubbed with paper powder, a recorded material is never wound, and no image defect is caused, and a device and a method for fixation and an image forming apparatus that use the same. <P>SOLUTION: The pressure member for fixation which has a heat-resisting base material and the release layer formed on the top surface of the heat-resisting base material and is made to abut against a fixing member to form a fixation nip is characterized in that the release layer is formed of a mixture of fluorocarbon resin and heat-resisting resin whose load flexural temperature of ASTM D648, 1.82 MPa is higher than the temperature of the pressure member in fixation and the angle of contact of the release layer with water is ≥80°. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing pressure member, a fixing device, a fixing method, and an image forming apparatus, and more particularly, a fixing pressure member, a fixing device, and a fixing device using an electrostatic transfer process such as an electrostatic copying machine and an electrostatic copying printer. The present invention relates to a method and an image forming apparatus.

Conventionally, as a fixing device used in an image forming apparatus such as a general electrophotographic copying machine, various fixing systems have been proposed and implemented. Of these, the roller fixing type is used, and in particular, a heat roll fixing method using a heating roller fixing device in which at least one of a pair of rollers is a heating roller heated by a heat source is mainly used.
Hereinafter, in the present invention, the roller in contact with the image bearing side surface of the recording material in the roller pair is referred to as a fixing roller or a heating roller, and the other roller is referred to as a pressure roller based on its function. .

By the way, various requirements and problems have been raised for the pressure roller.
For example, when the toner is melted and fixed, the pressure roller has a high temperature of about 200 ° C., and thus heat resistance and releasability have been required.

  Also, the pressure roller of a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine usually has a cleaning means such as a cleaning blade or a cleaning roller for the purpose of removing a release material, paper dust, and offset toner. They are arranged in contact with each other (see, for example, Patent Documents 1 and 2). Further, in order to prevent the recording material from being wrapped around the paper, there is a case where a separation claw for separating the recording material is disposed in contact with each of the fixing roller and the pressure roller (see, for example, Patent Document 3). In such an arrangement, the cleaning performance changes greatly due to subtle changes in the cleaning blade or cleaning roller material and contact pressure. For example, paper dust or offset on the cleaning blade edge or the cleaning surface of the cleaning roller. As a result, foreign matter such as toner adheres, and as a result, the pressure roller is damaged, and at the time of double-sided image formation, there is a problem in that the image on the side in contact with the pressure roller is disturbed.

  Also, the pressure roller surface is subject to wear due to the friction of the blade or other cleaning means, the recording material separation claw material, etc., and the recording that passes between the fixing roller and the pressure roller. There is also a problem of recording material rubbing that the material is also rubbed.

  Further, the coating layer of the pressure roller usually has a high resistance. Therefore, the surface of the fixing roller is largely charged by frictional charging due to friction with the contact member against the roller such as the recording material and the pressure roller, and the surface of the recording material is The toner is attracted to the surface of the fixing roller by electrostatic action, and so-called electrostatic offset phenomenon is likely to occur.

  In addition, in a roller having a fluororesin coating layer, the fluororesin has a property of being largely negatively (−) charged by rubbing against the recording material or the like. When the toner has a positive (+) polarity, the toner is negatively charged. There is a problem that it is attracted to the electric field of the electrically charged fluororesin coating layer and easily adheres to the surface of the fixing roller due to an electrostatic offset phenomenon.

  In addition, as a means for improving the wear resistance of the pressure roller, generally the wear resistance of fluororesin is relatively high such as glass powder, silica, silicon carbide powder, diamond powder, corundum powder, metal powder such as nickel and iron. It can be improved by mixing an inorganic filler with high hardness, but if the mixing amount is small, the effect of improving the wear resistance is not sufficient, and if the mixing amount is increased, the releasability becomes worse. Further, the surface property of the pressure roller is also deteriorated, and there is a problem that the effect of preventing offset is lowered.

  In addition, these fillers have poor dispersibility in the fluororesin, and even if they can be dispersed, the adhesiveness between the filler and the fluororesin is poor. Phenomenon such as detachment occurred. In the case of poor dispersion, a portion with less filler was first scraped into stripes or mottle due to durability, and toner was embedded in the scraped portion, often resulting in a decrease in non-adhesiveness of the pressure roller.

  Further, when the filler is detached, the toner is buried in the detached portion, or the removed filler acts as an abrasive on the contrary to accelerate the wear.

  Attempts were made to make the particle size of the filler finer, but the adhesion between the filler and the fluororesin was poor, and conversely the entire fluororesin layer was worn.

  Various proposals have been made so far to solve the above demands and problems, but none of them has sufficiently solved all these demands and problems (for example, Patent Documents 4 to 23). reference).

JP-A-8-87196 JP 2000-131991 A JP-A-10-31383 JP 2000-227110 A JP 2001-142338 A Japanese Patent Laid-Open No. 2002-31978 JP 2002-40842 A JP 2002-139944 A JP 2002-156858 A JP 2002-195248 A JP-A-5-27630 JP-A-6-3395 JP-A-6-27850 JP-A-7-92841 JP 7-137176 A Japanese Patent Laid-Open No. 7-302011 JP-A-8-87196 JP-A-8-197650 JP-A-8-267614 JP-A-9-126225 Japanese Patent Laid-Open No. 9-273542 JP-A-10-31383 JP-A-10-39667

As described above, the conventional pressure roller technology has demands and problems regarding wear resistance, offset resistance, releasability, and the like.
Therefore, the present invention has been made to solve the above-described demands and problems, and the release layer has excellent heat resistance, and is pressed by means such as a cleaning means such as a blade, a recording material separation claw, and a recording material. Is hard to be deformed, and even if the surface of the release layer is rubbed by the above-mentioned means or the like, and is not easily worn even when rubbed by various inorganic fillers contained in the paper powder, the pressure roller of the recording material, etc. An object of the present invention is to provide a fixing pressure member composed of a pressure roller or the like that does not cause wrapping around the image and therefore does not cause image defects due to paper wrapping, a fixing device using the same, a fixing method, and an image forming apparatus. To do.

  In order to solve the above-mentioned problems, the invention according to claim 1 has a heat-resistant substrate and a release layer provided on the surface of the heat-resistant substrate, and is fixed by contacting a fixing member. In the fixing pressure member for forming the nip, the release layer is formed of a mixture of a fluororesin and a heat resistant resin having a deflection temperature under load (ASTM D648, 1.82 MPa) higher than the temperature of the pressing member at the time of fixing. A fixing pressure member whose contact angle with water of the release layer is 80 ° or more is the most important feature.

  The invention according to claim 2 is characterized in that the fixing pressure member according to claim 1 is characterized in that the release layer is heat-treated at a temperature equal to or higher than the melting points of both the fluororesin and the heat-resistant resin. .

  According to a third aspect of the present invention, in the first and second aspects, the releasing layer has a sea-island structure in which the release layer has an island phase made of the fluororesin and a sea phase made of the heat-resistant resin. The member is the main feature.

  According to a fourth aspect of the present invention, the main feature of the third aspect is the fixing pressure member in which the distance between the island phase fluororesins is smaller than the toner particle size.

  The invention according to claim 5 is characterized in that, in any one of claims 1 to 4, a fixing pressure member containing a conductive filler in the heat-resistant resin is a main feature.

  The invention according to claim 6 is characterized in that, in any one of claims 1 to 5, a pressure member for fixing having an adhesive layer between the release layer and the underlying layer is a main feature.

  According to a seventh aspect of the invention, in any one of the first to sixth aspects, the release layer is directly formed on a base material made of the same heat-resistant resin as that used for the release layer. The main feature is the fixing pressure member.

  The invention according to claim 8 is characterized in that, in any one of claims 1 to 7, a pressure member for fixing having an elastic layer between the release layer and the substrate is a main feature.

  The invention according to claim 9 is characterized in that, in any one of claims 1 to 8, the fixing pressure member, wherein the heat-resistant resin is a resin that can be made into a solution at room temperature, is a main feature.

  According to a tenth aspect of the present invention, in any one of the first to ninth aspects, a fixing pressure member containing a heat conductive filler in the heat resistant resin of the release layer is a main feature.

  According to an eleventh aspect of the present invention, in the fixing device for forming a fixing nip by bringing the pressure member into contact with the fixing member, the fixing device using the fixing pressure member according to any one of the first to tenth aspects. Is the main feature.

  According to a twelfth aspect of the present invention, in the fixing method using the fixing device according to the eleventh aspect, an electrophotographic image fixing method for supplying a release agent to the surface of the release layer of the fixing member is a main feature.

  According to a thirteenth aspect of the present invention, the fixing device according to the eleventh aspect is characterized in that the fixing device includes means for supplying a release agent to the surface of the release layer of the fixing member.

  The invention according to claim 14 is characterized in that, in the fixing method using the fixing device according to claim 11 or 13, the fixing method for cleaning the surface of the release layer is a main feature.

  According to a fifteenth aspect of the present invention, the fixing device according to the eleventh or thirteenth aspect mainly includes a fixing device having means for cleaning the surface of the release layer.

  According to a sixteenth aspect of the present invention, an image forming apparatus using the fixing device according to any one of the eleventh, thirteenth, and fifteenth aspects is a main feature.

  According to the first aspect of the present invention, in the pressure member having a heat resistant base material and a release layer provided on the surface of the heat resistant base material, the pressure member is brought into contact with the fixing member to form a fixing nip. The release layer is formed of a mixture of a fluororesin and a heat-resistant resin in which the deflection temperature under load by ASTM D648, 1.82 MPa is higher than the temperature of the pressure member at the time of fixing, and the contact angle of the release layer with respect to water is The fixing pressure member, which is 80 ° or more, is difficult to be deformed even when pressed by a cleaning means such as a blade, so that it is difficult to bite, and therefore is not easily worn, and paper dust is generated and adheres to the pressure member. Even if the surface of the release layer is rubbed by various inorganic fillers contained in the paper paper powder, it is difficult to be worn, offset by wax from the toner, and applied to a pressure roller such as a hot melt adhesive. Winding of recording material A fixing pressure member that does not cause scratches can be obtained.

  According to claim 2, the fixing pressure member according to claim 1, wherein the release layer is heat-treated at a temperature equal to or higher than the melting points of both the fluororesin and the heat-resistant resin. Abrasion resistance can be further improved by compatibility or micro-dispersion in a state where both resins are melted.

  According to Claim 3, in Claims 1 and 2, the release layer has a sea-island structure that is an island phase made of the fluororesin and a sea phase made of the heat-resistant resin. The fixing pressure member has a structure that does not easily come off even when subjected to rubbing and can maintain wear resistance.

  According to a fourth aspect of the present invention, in the third aspect, the area where the toner is in direct contact with the heat-resistant resin by the fixing pressure member, wherein the interval between the island phase fluororesins is smaller than the toner particle size. Therefore, it is possible to obtain an advantageous structure for preventing offset.

  According to a fifth aspect of the present invention, there is provided a fixing pressure member comprising the heat resistant resin according to any one of the first to fourth aspects, wherein the heat resistant resin is more than the fluororesin. However, since the surface tension is small, the conductive filler can be more easily dispersed more uniformly, and resistance unevenness can be reduced.

  According to a sixth aspect of the present invention, there is provided a cleaning means such as a blade by means of the fixing pressure member having an adhesive layer between the release layer and the underlayer according to any one of the first to fifth aspects, It is possible to prevent the release layer from being peeled when it is rubbed with a recording material separation claw, a recording material or the like.

  According to Claim 7, the release layer according to any one of Claims 1 to 6 is directly formed on a substrate made of the same heat-resistant resin as that used for the release layer. Due to the fixing member for fixing, the adhesion between the heat-resistant substrate and the release layer can be improved without using an adhesive layer, and there is no need to apply and dry the adhesive layer. The number of processes can be reduced.

  According to an eighth aspect of the present invention, there is provided a fixing pressure member having an elastic layer between the release layer and the substrate according to any one of the first to seventh aspects, wherein the release layer is made of fluorine. Compared with the case where it is formed only with resin, it becomes possible to improve adhesion to the elastic layer by mixing the heat-resistant resin.

  According to a ninth aspect of the present invention, the fixing pressure member according to any one of the first to eighth aspects is characterized in that the heat resistant resin is a resin that can be made into a solution at room temperature. Since the leveling is performed, the smoothness of the coating film is good, and even when the surface shape of the release layer is transferred to the image at the time of fixing, the image quality is not deteriorated, and the fine unevenness of the substrate is also liquid. Can be sufficiently covered, and the adhesion to the substrate can be improved.

  According to a tenth aspect of the present invention, in the heat resistant resin of any one of the first to ninth aspects, the heat-resistant resin is contained in the heat-resistant resin of the release layer. Since the surface tension is smaller than that of fluororesin, it is possible to disperse the heat conductive filler more uniformly by including the heat conductive filler in the heat-resistant resin, and to perform uniform heat conduction. .

  According to an eleventh aspect of the present invention, in the fixing device for forming the fixing nip by bringing the pressure member into contact with the fixing member, the fixing pressure member according to any one of claims 1 to 10 is used. Due to the fixing device, the recording material separation claw, the temperature detection element, the pressure roller, etc. are not easily deformed, so that they are difficult to bite and wear, and are separated by various inorganic fillers contained in the paper powder. It is difficult to wear even by rubbing on the surface of the mold layer, and it is possible to prevent the recording material from being wound around the pressure roller by the wax extracted from the toner.

  According to a twelfth aspect of the present invention, there is provided a fixing method using the fixing device according to the eleventh aspect, wherein the release agent is supplied to the surface of the release layer of the fixing member. The release agent is partly transferred to the release layer of the pressure member when the fixing member and the pressure member are in direct contact with each other, so that the release agent component is held in the heat-resistant resin portion and the anti-offset coating layer Can exhibit stable non-stickiness over a long period of time.

  In the present invention, since the deflection temperature under load of the heat-resistant resin (ASTM D648, 1.82 MPa) is set larger than the temperature of the pressure member at the time of fixing, when pressed by the cleaning means and the release agent application means However, since they are difficult to deform, they are difficult to bite in, and therefore are not easily worn.

  In addition, the wax that comes out of the toner and adheres to the release layer side of the fixing member moves to the pressure member side when the fixing member and the pressure member are in direct contact with each other. The release layer does not touch, offset, or function as a hot melt adhesive and the recording material does not wrap around the pressure roller.

  According to a thirteenth aspect of the fixing device according to the eleventh aspect, the release agent applied by the fixing device further comprises means for supplying a release agent to the surface of the release layer of the fixing member. When the fixing member and the pressure member are in direct contact, a part of the fixing member moves to the release layer of the pressure member, so that the release agent component is retained in the heat-resistant resin portion, and the anti-offset coating layer is stable for a long time. Can exhibit tackiness.

  According to the fourteenth aspect of the present invention, in the fixing method using the fixing device according to the eleventh or thirteenth aspect, the fixing method is characterized in that the release layer surface is cleaned. Can be formed.

  According to the fifteenth aspect of the present invention, the fixing device according to the eleventh or thirteenth aspect has a means for cleaning the surface of the release layer, thereby forming a good image that is not affected by abrasion due to cleaning. It is possible to obtain an image forming apparatus.

  According to a sixteenth aspect, an image forming apparatus having the characteristics of the first to fifteenth aspects is obtained by an image forming apparatus using the fixing device according to any one of the eleventh, thirteenth, and fifteenth aspects. It becomes possible.

Hereinafter, the present invention will be described in detail starting from the main item.
The most basic invention of the present invention is a pressure member that has a heat-resistant substrate and a release layer provided on the surface of the heat-resistant substrate, and is brought into contact with the fixing member to form a fixing nip. The release layer is formed of a mixture of a fluororesin and a heat-resistant resin having a deflection temperature under load of ASTM D648, 1.82 MPa that is higher than the temperature of the pressure member at the time of fixing, and the release layer with respect to water A fixing pressure member having a contact angle of 80 ° or more.

In the present invention, the release layer is formed of a mixture of a fluororesin and a heat-resistant resin on the surface of the fixing pressure member, so that the heat resistance of the release layer is particularly excellent.
In addition, since the deflection temperature under load (ASTM D648, 1.82 MPa) of the heat-resistant resin, which is one resin of the mixture, is set higher than the temperature of the pressure member at the time of fixing, cleaning means such as a blade, recording material separation Even when pressed with a nail, a recording material or the like, they are not easily deformed, so that they do not easily bite in, and therefore are not easily worn.

  In addition, when a large amount of paper (recording material) is passed, paper dust is generated from the paper, adheres to the fixing member, and the release layer surface is rubbed by various inorganic fillers contained in the paper powder. It is hard to wear for the reason.

  In addition, the wax that comes out of the toner and adheres to the release layer side of the fixing member moves to the pressure member side when the fixing member and the pressure member are in direct contact with each other. The release layer does not touch, offset, or function as a hot melt adhesive and the recording material does not wrap around the pressure roller.

However, if the contact angle of the release layer of the fixing pressure member with respect to water is less than 80 °, the toner resin itself becomes too wet, and the adhesive force of the toner resin itself increases abruptly, which exceeds the effect of preventing adhesion by wax, and the entire toner is cleaned. It cannot be transferred to the means, and paper wrapping and image defects occur.
In the present invention, the contact angle was measured by a droplet method at room temperature using a CA-X type manufactured by Kyowa Interface Science Co., Ltd., by forming a flat test piece of the surface layer material of the heat fixing member.

  In the present invention, the thickness of the release layer is preferably 5 to 100 μm, more preferably 10 to 50 μm. If it is less than 5 μm, the life in which offset occurs when paper is passed is shortened, and if it exceeds 100 μm, cracks tend to occur.

The fluororesin used for the release layer is not particularly limited as long as it contains a fluorine atom in the molecule.
Specifically, polytetrafluoroethylene (PTFE) and its modified product, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoro Propylene copolymer (FEP), tetrafluoroethylene-vinylidene fluoride copolymer (TFE / VdF), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPA), polychlorotrifluoroethylene (PCTFE) ), Chlorotrifluoroethylene-ethylene copolymer (ECTFE), chlorotrifluoroethylene-vinylidene fluoride copolymer (CTFE / VdF), polyvinylidene fluoride (PVdF), polyvinyl fluoride PVF) and the like.

As the heat-resistant resin used for the release layer, a resin having a deflection temperature under load (ASTM: D648, 1.82 MPa) higher than the temperature of the fixing member at the time of fixing may be used.
For example, when the temperature of the fixing member is 150 ° C., specifically, polyamideimide (PAI), polyethersulfone (PES), polyetherimide (PEI), polyetheretherketone (PEEK), polyetherketone (PEK) ), Polyether nitrile (PEN), polyarylate (PAR), liquid crystal polymer (LCP), polybenzimidazole (PBI), polyimide (PI), polyphenylene sulfide (PPS) and the like can be used. These may be used in combination.

  In the present invention, it is necessary to adjust the contact angle of the release layer with respect to the water of the release layer within the range of 80 ° or more. As the method, a fluororesin that is a constituent material of the release layer is used. A method of changing the mixing ratio between the heat-resistant resin and the heat-resistant resin and controlling the contact angle with water can be employed. For example, when the fluororesin is PFA and the heat-resistant resin is polyimide, as a method of setting the contact angle to 80 ° or more, the ratio of polyimide may be mixed within a range of 50% by weight or less to form a release layer.

  In the present invention, the fixing pressure member can be applied to any form such as a pressure roller and a pressure belt.

Next, in the present invention, the release layer is subjected to a heat treatment at a temperature equal to or higher than the melting point of the two in a state where the fluororesin and the heat-resistant resin are mixed, so that both the resins are in a compatible state. Therefore, it is possible to obtain a dispersed phase suitable for the pressure member at the time of cooling, and to further improve the wear resistance. This will be described in detail below with reference to FIGS.
FIG. 1 is a schematic plan view and a schematic cross-sectional view of a release layer showing a resin structure of a fixing pressure member of the present invention.
FIG. 2 is a schematic plan view and a schematic cross-sectional view of a release layer showing a resin configuration opposite to that of FIG. 1 of the fixing pressure member of the present invention.
FIG. 3 is a schematic cross-sectional view of the release layer showing the relationship between the resin configuration of the fixing pressure member of the present invention and the toner particle size.

  As shown in FIG. 1, when the heat-resistant resin 102 constituting the release layer is an island phase, a cleaning means such as a blade, a release agent coating means, a recording material separation claw, a temperature detection element, a pressure roller, a recording When subjected to rubbing with a material or the like, the heat-resistant layer exposed on the surface may be detached, and in that case, the surrounding fluororesin 101 is easily worn.

  In contrast, when the heat-resistant resin 102 is in the sea phase as shown in FIG. 2, it has a structure that does not easily come off even when rubbed, and is advantageous in maintaining wear resistance.

  As shown in FIG. 3, when the heat-resistant resin 102 is a sea phase and the interval between the fluorine resins 101 in the island phase is smaller than the particle size of the toner 104, the area where the toner 104 directly contacts the heat-resistant resin 102. Therefore, the structure is advantageous for preventing offset.

Moreover, electrostatic offset can be prevented by including in the heat resistant resin a conductive filler having a resistance of 10 ¹⁰ Ω · cm or less.
The amount of the conductive filler is preferably 1 to 50% by weight with respect to the fluororesin, and is preferably 5 to 75% by weight in total with the heat resistant resin in order to maintain releasability.

  The electrically conductive particles used as the electrically conductive filler include conductive polymer particles such as polyacetylene, polypyrrole and polythiophene, carbon particles such as ketine black and acetylene black, graphite particles, metals such as silver, nickel and copper, and alloys thereof. And particles of composite metals plated on mica, carbon, glass, etc., metal oxide particles such as tin oxide and indium oxide, anion, cation, nonion, and amphoteric surfactant particles.

Next, in the present invention, by having an adhesive layer between the release layer and the underlying layer, a cleaning means such as a blade, a release agent coating means, a recording material separation claw, a temperature detection element, a pressure roller, etc. Thus, it is possible to prevent the release layer from being peeled when subjected to rubbing. Here, as the adhesive layer, various commercially available heat-resistant primers that enhance the adhesion between the heat-resistant substrate and the release layer can be used.
For example, for an aluminum roller, a polyimide primer, a polyamideimide primer, a polyethersulfone primer, and a mixed primer thereof are preferably used. For example, for a heat-resistant endless belt layer made of polyimide resin, a polyimide-based primer, a fluorine-based primer, or a mixed primer is preferably used.

  In the present invention, in order to improve the adhesion between the heat-resistant substrate and the release layer, for example, a polyimide resin as a heat-resistant resin constituting the release layer with respect to a heat-resistant endless belt layer of polyimide resin. By directly forming the release layer on the heat-resistant endless belt layer, the adhesion between the heat-resistant substrate and the release layer can be improved without using an adhesive layer, and cleaning of blades, etc. It is possible to prevent the release layer from being peeled when it is rubbed by the means, the release agent application means, the recording material separation claw, the temperature detection element, the pressure roller, or the like. For this reason, it is not necessary to apply and dry the adhesive layer, and the number of steps can be reduced.

  In the case where the fixing member has an elastic layer, the fixing nip can be formed by the pressure member according to claims 1 to 7. However, in order to form the fixing nip when the fixing member does not have the elastic layer, or the fixing nip width. A pressure member provided with an elastic layer is necessary to increase the line speed and increase the linear speed of paper passing.

  In the present invention, it is possible to improve the adhesion to the elastic layer by mixing the heat-resistant resin as compared with the case where the release layer is formed of only the fluororesin, and cleaning of the blade and the like. It is possible to prevent the release layer from being peeled off from the elastic layer when it is rubbed by the means, the recording material separation claw or the like.

Further, in the present invention, the leveling after coating is performed by using a resin that can be dissolved at room temperature as the heat-resistant resin, so that leveling after coating is performed, and the smoothness of the coating film is good. Even if the surface shape of the release layer is transferred to the image during double-sided fixing, it is possible to suppress deterioration in image quality. Further, even if there are fine irregularities on the substrate, it can be sufficiently covered because it is liquid, and the contact area is increased, so that the adhesion to the substrate is improved.

Examples of the heat-resistant resin used as the heat-resistant resin coating layer in the present invention include polybenzimidazole (PBI), polyimide (PI), polyamideimide (PAI), polyethersulfone (PES), and polyphenylene sulfide (PPS). The heat resistant resin is preferably used as a precursor solution or in the form of a solution. In these solutions, the fluororesin powder can be easily mixed and dispersed, and can be easily coated on a metal cylindrical metal core with good surface smoothness by dipping or coating. If the resin is thermoplastic, just evaporate the solvent, or if the resin is thermosetting, heat evaporate after evaporating the solvent to form a heat-resistant resin layer on the metal cylindrical cored bar Can do.
Precursor solutions of polyimide (PI) and polyamideimide (PAI) are known, and polybenzimidazole (PBI) is dissolved in dimethylacetamide (DMA), and polyethersulfone (PES) is dimethylformamide, methylene chloride. , N-methyl-2-pyrrolidone is known to be soluble and these solutions can be used.

  Moreover, heat conductivity can be made favorable by making a fluororesin contain a heat conductive filler. Specifically, as the thermally conductive particles, diamond, silver, copper, aluminum, marble, glass, boron nitride, alumina, silicon carbide, potassium titanate, aluminum nitride, boron nitride, mica, silica, titanium oxide, Examples thereof include particles of magnesium oxide, beryllium oxide, talc, calcium carbonate, and a mixture of two or more kinds of these particles. These addition amounts are preferably in the range of 10 to 50% by weight with respect to the heat-resistant resin in order to maintain the releasability.

  FIG. 4 is a schematic configuration diagram of the fixing device of this embodiment using the fixing pressure member according to claim 1. The fixing device includes an upper fixing roller 1 (heating roller) and a lower pressure roller 2 (fixing pressure member) which are pressed in parallel with each other with a predetermined pressing force.

  There is a heat source 3 such as a halogen heater built in the fixing roller 1, and a temperature detection element 4 such as a thermistor in contact with the surface of the fixing roller 1, and the surface temperature of the fixing roller 1 is detected by this element 4. The energization of the heat generating source 3 is controlled by a control circuit (not shown) according to the information, and the surface temperature of the fixing roller 1 is managed to a predetermined temperature.

  There is a recording material separation claw 6 a that is urged against and brought into contact with the fixing roller 1 by a spring 7 a, and functions to separate the recording material that adheres to the surface of the fixing roller 1 and winds from the fixing roller 1. As the pressure roller 2, a surface layer of the cored bar 2b coated with the release layer 2a was used. There is a recording material separating claw 6b that is urged against and brought into contact with the pressure roller 2 by a spring 7b. The recording material separation claw 6b adheres to the surface of the pressure roller 2 and acts to separate the recording material to be wound from the fixing roller 1. To do.

The roller pair is rotationally driven at a predetermined speed by a driving means (not shown). A recording material P on which an unfixed toner image T is formed and supported by an image forming unit (not shown) is introduced into a pinching portion (fixing nip portion, nip width 5 to 6 mm) N of the roller pair. The toner image is fixed by heat and pressure.

In the present invention, the release layer is formed of a mixture of a fluororesin and a heat-resistant resin on the surface of the pressure roller 2 which is a fixing pressure member, so that the heat resistance of the release layer is excellent.
In addition, since the deflection temperature under load (ASTM D648, 1.82 MPa) of the heat-resistant resin is set to be higher than the temperature of the pressure member at the time of fixing, it is deformed even when pressed by a cleaning means, a recording material separation claw, or the like. Since they are difficult, they are difficult to bite and therefore wear.

Further, when a large amount of paper (recording material) is passed, paper dust is generated from the paper, which adheres to the pressure roller 2 and rubs the surface of the release layer by various inorganic fillers contained in the paper powder. However, it is difficult to wear for the same reason.
Further, the wax that comes out of the toner and adheres to the release layer side of the fixing roller 1 moves to the pressure roller 2 side when the fixing roller 1 and the pressure roller 2 are in direct contact with each other. There is an effect that the recording material does not touch the release layer, offset, or function as a hot melt adhesive and the recording material does not wrap around the pressure roller.

FIG. 5 is a schematic configuration diagram of the fixing device of the present invention in which a release agent supply member is further arranged in the fixing device of FIG. Constituent member portions common to those in FIG. 4 are given the same reference numerals, and description thereof is omitted.
There is a roller body 5 as a release agent supply member / cleaning member for the fixing roller 1. The roller body 5 includes a cored bar 5a and a release agent-impregnated heat-resistant felt 5b, and is controlled to contact and separate from the fixing roller 1 by an eccentric cam (not shown).
A cleaning roller 201 that removes excess release agent, toner, and paper dust on the surface of the pressure roller 2 is pressed against the pressure roller 2 by a spring 8.

  In the present invention, since the deflection temperature under load of the heat-resistant resin (ASTM D648, 1.82 MPa) is set higher than the temperature of the pressure roller 2 at the time of fixing, it is pressed by the cleaning means and the release agent application means. Even in this case, since they are difficult to deform, they are difficult to bite in.

  Further, when a release agent is applied to the release layer of the fixing roller 1 in this embodiment, a part of the applied release agent is applied when the fixing roller 1 and the pressure roller 2 are in direct contact with each other. Move to 2 release layer. As a result, the release agent component is held in the heat resistant resin portion, and the offset preventing coating layer can exhibit stable non-adhesiveness over a long period of time.

In Examples 1 to 4 in Table 1, the release layer contains a mixture of a fluororesin and a heat-resistant resin as described in the present invention and a conductive filler, and the contact angle of the release layer with respect to water is 80 ° or more. An actual machine evaluation result by a fixing device using a pressure member is shown.
The fixing device used a fixing roller as a fixing pressure member, and the evaluation was made on the influence on the charging potential of the fixing roller, the offset property at the time of double-sided fixing, and the durability life. Table 1 also shows Comparative Examples 1 and 2.

<Models used, evaluation criteria>
Model used: Spirio 3550 (Ricoh Co., Ltd.)
Charging potential: A surface potential meter Trek Model 347 was used to measure the surface of the fixing roller during paper feeding, and the time average was calculated.
Offset property: 100 ruled line charts were continuously copied and evaluated in four stages (good → ◎ → ○ → Δ → × → bad).
Durability life: Four stages were evaluated based on the amount of scraping on the surface after continuous paper passing (good → ◎ → ○ → △ → × → bad).
Temperature distribution: A thermistor was attached to the center and both ends of the pressure roller in the axial direction, and the temperature difference was measured and evaluated in four stages (temperature difference small → ◎ → ○ → Δ → × → large).

FIG. 4 is a schematic plan view and a schematic cross-sectional view of a release layer showing a resin configuration of a fixing pressure member of the present invention. FIG. 2 is a schematic plan view and a schematic cross-sectional view of a release layer showing a resin configuration opposite to that of FIG. 1 of a fixing pressure member of the present invention. FIG. 3 is a schematic cross-sectional view of a release layer showing a relationship between a resin configuration of a fixing pressure member of the present invention and a toner particle diameter. It is a schematic block diagram of the fixing device of the present invention in which the fixing pressure member is a pressure roller and has a separation claw. FIG. 5 is a schematic configuration diagram of a fixing device of the present invention in which a release agent supply member is further provided in the fixing device of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 2a Release layer 3 Heat generation source 4 Temperature detection element 5a Core metal 5b Release agent impregnation heat resistant felt 6a, 6b Separation claw 7a, 7b, 8 Spring 201 Cleaning roller 101 Fluoro resin 102 Heat resistant resin 103 Release agent 104 Toner

Claims (16)

  In a fixing pressure member having a heat-resistant base material and a release layer provided on the surface of the heat-resistant base material, and contacting the fixing member to form a fixing nip, the release layer includes: It is formed of a mixture of a fluororesin and a heat-resistant resin whose deflection temperature under load (ASTM D648, 1.82 MPa) is larger than the temperature of the pressure member at the time of fixing, and the contact angle of the release layer with respect to water is 80 ° or more. A fixing pressure member.   2. The fixing pressure member according to claim 1, wherein the release layer is heat-treated at a temperature equal to or higher than the melting points of both the fluororesin and the heat-resistant resin.   The fixing pressure member according to claim 1, wherein the release layer has a sea-island structure that is an island phase made of the fluororesin and a sea phase made of the heat-resistant resin.   4. The fixing pressure member according to claim 3, wherein the interval between the island phase fluororesins is smaller than the toner particle diameter.   5. The fixing pressure member according to claim 1, wherein the heat resistant resin contains a conductive filler. 6.   6. The fixing pressure member according to claim 1, further comprising an adhesive layer between the release layer and a base thereof.   The fixing layer according to claim 1, wherein the release layer is directly formed on a base material made of the same heat-resistant resin as that used for the release layer. Pressure member.   8. The fixing pressure member according to claim 1, further comprising an elastic layer between the release layer and the base material.   9. The fixing pressure member according to claim 1, wherein the heat-resistant resin is a resin that can be made into a solution at room temperature.   10. The fixing pressure member according to claim 1, wherein a heat conductive filler is contained in the heat resistant resin of the release layer.   11. A fixing device using a fixing pressure member according to claim 1, wherein a fixing member is brought into contact with a fixing member to form a fixing nip.   The fixing method using the fixing device according to claim 11, wherein a release agent is supplied to the surface of the release layer of the fixing member.   12. The fixing device according to claim 11, further comprising means for supplying a release agent to the surface of the release layer of the fixing member.   14. A fixing method using the fixing device according to claim 11, wherein the surface of the release layer is cleaned.   14. The fixing device according to claim 11, further comprising means for cleaning the surface of the release layer.   An image forming apparatus using the fixing device according to claim 11.

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