JP2005157173A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-fixing member having a surface layer excellent in flexibility, scratch resistance and abrasion resistance and an outermost layer excellent in toner release property, and capable of obtaining a high-quality toner fixed image, and use thereof It is to provide a highly durable fixing device.
In a fixing device having a heat fixing member and a pressure fixing member pressed against the heat fixing member, the heat fixing member has at least a fluoroelastomer surface layer in which carbon black subjected to surface oxidation treatment is dispersed. And a fixing device comprising oil supply means for applying dimethyl silicone oil having an unsaturated bond to the surface of the heat fixing member.
[Selection] Figure 1

Description

  The present invention relates to a fixing device used in an electrophotographic image forming apparatus such as a copying machine or a laser beam printer (LBP), and more particularly to a fixing device provided with a heat fixing member whose surface layer is made of a fluoroelastomer.

  In general, an electrophotographic image forming apparatus such as a copying machine or LBP applies heat and pressure to a recording material such as paper or an OHP sheet on which a toner image is electrostatically formed to fix the toner on the recording material. is required. This is called a heat-pressure fixing device or simply a fixing device. This fixing device has a pair of pressure-contacting rotating bodies, and a recording material having unfixed toner is sandwiched and conveyed between the rotating bodies. The pressure contact portion between the rotating members is called a nip, and unfixed toner is heated and softened in the nip, pressed against the recording material by pressure, and then cooled and solidified to form a semi-permanent image on the recording material. It is fixed.

  In general, the upper rotating body in contact with the unfixed toner uses various forms such as a roller, a belt, and a film. When the form is a roller, it is called a fixing roller, and is in the form of a belt. Called the fixing belt. The roller form is often used in high-speed machines with relatively fast copying or printing speed due to the large heat capacity of the heat-fixing member. The belt or film form has a low heat capacity and has a warm-up time. Short and often used on low speed machines. Also, the lower rotating body that is less in contact with unfixed toner uses the form of a roller, a belt, and the like, which are called a pressure roller and a pressure belt, respectively. The fixing roller and the fixing belt are collectively called a heat fixing member, and the pressure roller and the pressure belt are collectively called a pressure fixing member.

  The heat fixing member for fixing these toners by heat and pressure is formed by laminating a layer made of a heat resistant elastic body or resin on a cylindrical base material in a single layer or multiple layers. Among these layers, the surface layer is particularly close to the unfixed toner image, and thus has a great influence on the image quality of the fixed image.

  Generally, examples of the material used for the elastic layer include silicone rubber and fluoroelastomer (fluororubber). Silicone rubber and fluoroelastomer are excellent in heat resistance and chemical resistance, and when used as a material for the elastic body layer, the flexibility can be maintained for a long time. In addition to the elastic body, a fluororesin may be used for the surface layer of the heat fixing member. A fluororesin is excellent in heat resistance and chemical resistance, and has excellent non-adhesiveness and low friction and wear, but has high hardness and poor flexibility.

  The flexibility of the surface layer affects the image quality after fixing. In order to fix the toner with high accuracy, a surface layer made of a flexible elastic body is desirable, and the aforementioned silicone rubber and fluoroelastomer are suitable.

  In addition to the flexibility that affects the image quality after fixing, important properties required for the surface layer include toner release properties, scratch resistance, and abrasion resistance. Toner release is the difficulty of toner adhesion. If the toner is likely to adhere, that is, if the toner release property is poor, the toner may be missing from the fixed image, or the toner adhering to the surface of the heat fixing member may be fixed on the recording material again, causing toner contamination. Or These are called toner offsets.

  Since the surface layer of the heat fixing member is close to the unfixed toner, an excellent toner release property is required.

  In particular, in a full-color image forming apparatus, a higher toner release property is required on the surface layer than in monochrome. This is because, in a full-color image forming apparatus, it is necessary to fix various toners, that is, electrostatic images in which black, cyan, magenta, and yellow toners are laminated on a recording material. This is because a good color mixing property is required at the time of pressurization, and a toner having a high melting property is used.

  Conventionally, in a fixing device of a full-color image forming apparatus, a constant amount of non-functional dimethyl silicone oil or modified silicone oil is always applied for the purpose of assisting toner release. In some cases, oil stickiness occurs on the surface of a recording material such as paper, which is an image after fixing, and it becomes difficult to perform writing with a pen or the like.

  Next, scratch resistance and abrasion resistance are the difficulty of scratching and the difficulty of wearing. In many cases, a web, an oil application member, a thermistor, or the like is in contact with the surface layer, and the friction with the contact member may cause scratches or wear. Further, when the recording material is nipped by the nip and conveyed, friction may occur between the recording material and the same phenomenon. When scratches or wear occur in this way, irregularities occur on the surface of the surface layer.

  In particular, when unevenness is generated on the surface layer of the heat fixing member, a minute amount of offset toner accumulates there, causing toner offset, resulting in an image defect.

  Therefore, the material used for the surface layer is required to have flexibility, toner release properties, scratch resistance and abrasion resistance.

  Among these three required characteristics, one of materials excellent in flexibility, scratch resistance and abrasion resistance is fluoroelastomer.

  Conventional fluoroelastomers used for the surface layer are reinforced with binary copolymers of vinylidene fluoride and hexafluoropropylene, or fluoropolymers made of terpolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene. For this purpose, carbon black blended ones with polyamine crosslinking or polyol crosslinking have been mainly proposed. However, only this fluoroelastomer surface layer has high surface energy, so that sufficient toner release properties cannot be obtained. There was a problem. In order to solve this problem, an interface barrier layer having a low surface energy may be interposed between the fluoroelastomer surface and the toner, and the following means have been proposed.

  For example, the elastomeric surface consists of poly (vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene) in which vinylidene fluoride is present in an amount of less than 40 mol%, which is substantially non-reactive with the elastomer. The fusion member is present in an amount sufficient for the metal oxide to interact with the functional group-containing polymer release agent to provide an interface barrier layer between the elastomer surface layer and the toner (Japanese Patent Publication No. 07-076856). Issue).

  Further, as a means for improving the surface stickiness of a recording material such as paper as an image after fixing, heat-resistant fluorine containing a fluorosurfactant so that the mixing ratio with the fluororubber is 0.3 to 10% by weight. A mold release agent provided with a rubber layer on the peripheral surface, and supplying the modified silicone oil to the surface of the heat-resistant fluororubber layer so as to have an average coating amount of 0.03 to 5 mg per area corresponding to one A4 sheet A fixing device having a supplying means has been proposed (Japanese Patent Laid-Open No. 10-020699).

  These prior arts include a modified silicone on the surface of the fluoroelastomer due to the intermolecular force generated between the metal oxide dispersed in the surface of the fluoroelastomer and the modified silicone oil supplied from the outside. An oil interface barrier layer is formed and retained.

  However, the modified silion oil used in the above-mentioned conventional example has high self-reactivity and is not very excellent in heat resistance, so it may cause discoloration or gelation, which adversely affects the image after fixing. There was a thing. In addition, since the intermolecular force generated between the fluoroelastomer surface layer and the modified silicone oil interface barrier layer is relatively small, the modified silicone oil is easily detached from the surface layer, and a large amount of modified silicone oil must be constantly supplied. There were times when I didn't. Thus, the present invention provides means for solving such problems.

  An object of the first invention according to the present application is to provide a high-quality toner-fixed image including a heat-fixing member having a surface layer excellent in flexibility, scratch resistance and abrasion resistance, and an outermost layer excellent in toner release properties. And a fixing device having high durability for use.

  The object of the second invention according to the present application is to provide a surface-oxidized carbon black having sufficient reactivity with dimethyl silicone oil having an unsaturated bond supplied from the outside.

  The object of the third invention according to the present application is to provide a surface-oxidized carbon black having sufficient reaction sites with dimethyl silicone oil having an unsaturated bond supplied from the outside.

  The object of the fourth invention according to the present application is to not adversely affect the surface energy toner release property of the surface layer of the fluoroelastomer by blending the surface-oxidized carbon black.

  The object of the fifth invention according to the present application is to provide an oil particularly excellent in heat resistance among dimethyl silicone oils having an unsaturated bond.

An object of the sixth invention of the present application is to provide a dimethyl silicone oil having an unsaturated bond that can be effectively supplied from the outside to the surface of the heat fixing member.
A seventh object of the present invention is to provide a fixing device in which the amount of oil supplied from the outside to the surface of the heat-fixing member is very small and oil stickiness does not occur on the surface of a recording material such as paper after fixing. It is.

  An object of the eighth invention according to the present application is to provide an oil supply means which does not cause oil stickiness on the surface of a recording material such as paper after fixing.

  An object of the ninth invention of the present application is to provide a fluoroelastomer surface layer having a relatively low surface energy and a relatively excellent toner release property.

  An object of a tenth invention according to the present application is to provide a fixing device including a heat fixing member having low surface energy and excellent toner release properties in the initial stage.

  An object of the eleventh aspect of the present invention is to provide a fixing device including a heat fixing member excellent in heat transfer to the surface.

  An object of a twelfth aspect of the present invention is to provide a fixing device suitable for a high speed machine.

  An object of the thirteenth invention according to the present application is to provide a fixing device suitable for a low speed machine.

  In order to achieve the above object, a first invention according to the present application is directed to a fixing device having a heat fixing member and a pressure fixing member pressed against the heat fixing member. The heat fixing member is subjected to surface oxidation treatment. A fixing device comprising at least a fluoroelastomer surface layer in which carbon black is dispersed, and an oil supply means for applying dimethyl silicone oil having an unsaturated bond to the surface of the heat fixing member, The surface-oxidized carbon black particles on the surface of the fluoroelastomer surface react with the oxygen-containing functional groups on the surface of the carbon black particles and the dimethyl silicone oil having an unsaturated bond supplied from the outside reacts with the surface of the fluoroelastomer surface by chemical bonding. Since the surface layer can always be formed, it has excellent flexibility, scratch resistance, and abrasion resistance. Surface layer, and a heating fixing member having a top surface with excellent toner release properties, it is possible to obtain a high-quality toner fixed image, and it is possible to provide a high fixing device of its use durability.

  Next, a second invention according to the present application for achieving the above object is a fixing device in which the pH value of the surface-oxidized carbon black is in the range of 2 to 4, and is supplied from the outside. It is possible to provide a surface-oxidized carbon black having sufficient reactivity with dimethylsilicone oil having an unsaturated bond.

Next, a third invention according to the present application for achieving the above object is a fixing device in which the surface oxidation-treated carbon black has a specific surface area (STSA) in the range of 50 to 400 m ² / g. Thus, it is possible to provide a surface-oxidized carbon black having sufficient reaction sites with dimethyl silicone oil having an unsaturated bond supplied from the outside.

  Next, a fourth invention for achieving the above object is that the blending amount of the surface-oxidized carbon black is 0.1-5 with respect to 100 parts by mass of the fluoropolymer that becomes a fluoroelastomer by crosslinking. In the fixing device in the range of part by mass, by reducing the blending amount of the surface oxidized carbon black, it is possible not to adversely affect the surface energy toner release properties of the fluoroelastomer surface layer.

  Next, a fifth invention for achieving the above object is a fixing device characterized in that the dimethyl silicone oil having an unsaturated bond is a dimethyl silicone oil having at least one vinyl group in the molecule. Thus, among dimethylsilicone oils having an unsaturated bond, an oil particularly excellent in heat resistance can be provided.

Next, a sixth invention for achieving the above object is a fixing device in which the viscosity of the dimethyl silicone oil having at least one vinyl group in the molecule is in the range of 100 to 20000 mm ² / s (25 ° C.). Thus, oil that can be effectively supplied from the outside to the surface of the heat fixing member can be provided.

  Next, a seventh invention for achieving the above object is a fixing device wherein the supply amount of the oil supply means is in an average range of 0.01 to 1 mg per area corresponding to one A4 sheet, It is possible to provide a fixing device in which the amount of oil supplied is small and oil stickiness does not occur on the surface of a recording material such as paper after fixing.

  Next, an eighth invention for achieving the above object is characterized in that the oil supply means contains a dimethyl silicone oil having the unsaturated bond in advance in a web formed of heat-resistant fibers, It is a fixing device that supplies oil while pressing a web against the heat fixing member, and can provide an oil supply means that does not cause oil stickiness on the surface of a recording material such as paper after fixing.

  Next, a ninth invention for achieving the above object is that the surface-layer fluoroelastomer of the heat-fixing member has vinylidene fluoride, tetrafluoroethylene, and perfluoromethyl vinyl ether each having at least one of iodine and bromine in the molecule. Can provide a fluoroelastomer surface layer having a relatively low surface energy and a relatively excellent toner release property. .

  Next, a tenth invention for achieving the above object comprises a fluoroelastomer surface layer according to the ninth invention and an outermost layer formed on the surface layer by chemically bonding a liquid silicone polymer to the fluoroelastomer. It is possible to provide a fixing device including a heat fixing member having a low surface energy and an excellent toner release property in the initial stage.

  Next, an eleventh invention for achieving the above object is that the heat fixing member comprises a cylindrical base material, a base layer made of heat-resistant and heat-conductive silicone rubber, a surface layer made of a fluoroelastomer, silicone The fixing device is composed of a polymer outermost layer, and the total thickness of the fluoroelastomer surface layer and the silicone polymer outermost layer is in the range of 5 to 100 μm, and is excellent in heat transfer to the surface of the heat fixing member. A fixing device can be provided.

  Next, a twelfth invention for achieving the above object is the fixing device according to claim 1, wherein the heat fixing member has a roller shape, and is suitable for a high speed machine. A fixing device can be provided.

  Next, a thirteenth invention for achieving the above object is the fixing device according to claim 1, wherein the heat fixing member has a belt shape and is suitable for a low speed machine. A fixing device can be provided.

  As described above, the heat fixing member using the fluoroelastomer in which carbon black subjected to surface oxidation treatment is dispersed on the surface layer of the present invention, and the oil for applying dimethyl silicone oil having an unsaturated bond on the surface of the heat fixing member A heat fixing member having a surface layer excellent in flexibility, scratch resistance and abrasion resistance, and an outermost layer excellent in toner release property is obtained by a fixing device provided with a supplying means, and a high-quality toner fixed image is obtained. And a fixing device having high durability for use can be provided.

  Next, the present invention will be described in further detail.

The surface-oxidized carbon black to be dispersed in the surface layer of the fluoroelastomer of the present invention belongs to what is generally called carbon black for color (ink). It has been subjected to oxidation treatment. These are mainly blended in plastics, paints and inks for the purpose of coloring. Examples of the type include channel black and furnace black depending on the production method, but currently, furnace black which has no environmental pollution problem during the production of carbon black is often used. Of the furnace black for color, the surface of the carbon black particles subjected to surface oxidation treatment has a large number of oxygen-containing functional groups such as hydroxyl groups, carboxyl groups, and quinone groups. Hydrogen ions ( Since H ⁺ ) is released at a certain concentration, it is sometimes called acidic carbon. This surface-oxidized carbon black has a slight radical reactivity and a certain degree of ionic reactivity due to a small amount of hydrogen present on the particle surface and a large number of oxygen-containing functional groups. The amount of the oxygen-containing functional group present on the surface of the carbon particles is evaluated by% volatile content when the carbon black is heated. The heating condition is generally about 950 ° C. for about 7 minutes. The volatile content of the carbon black subjected to the surface oxidation treatment is about 1 to 11%, which is approximately at least 10 times that of other carbon blacks not subjected to the surface oxidation treatment. For this reason, the pH value falls in the acidic region. In addition, the primary particle diameter of such acidic carbon black is about 10 to 100 nm.

  Carbon black generally blended with fluoroelastomers is called medium thermal carbon black (MT carbon). The manufacturing method is different from the above-mentioned furnace black. Even if blended, the crosslinking reaction is not affected, the physical properties of the rubber are not impaired, and high filling is possible. Since the particle diameter of this MT carbon is as large as about 200 to 400 nm, the specific surface area is small, the volatile content during heating is 0.1% or less, and the pH value is about neutral at about 8 to 10, so that carbon black particles There are almost no oxygen-containing functional groups on the surface.

  The dimethyl silicone oil having an unsaturated bond supplied from the outside to the surface of the heat-fixing member of the present invention, that is, the surface of the fluoroelastomer surface in which carbon black subjected to surface oxidation treatment is dispersed is, for example, dimethyl silicone having a carbon-carbon double bond It is an oil, and dimethyl silicone oil having a vinyl group, an allyl group, etc. as a functional group can be considered, but since it has excellent heat resistance and is relatively easily available, it has at least one vinyl group in the molecule. Dimethyl silicone oil is preferred. The molecular structure of the dimethyl silicone oil having at least one vinyl group in the molecule is preferably a straight chain, and particularly preferably one having a vinyl group at one or both ends.

  The coating amount of dimethyl silicone oil having such an unsaturated bond is preferably in the range of 0.01 to 1 mg on average per area corresponding to one A4 sheet. If it is less than 0.01, the amount of oil supplied is too small, and it is difficult to uniformly apply to the entire surface of the heat fixing member, which is not preferable. On the other hand, if it exceeds 1 mg, oil stickiness may occur on the surface of a recording material such as paper as an image after fixing, which is not preferable.

  As one of the specific means for supplying the amount of 0.01 to 1 mg / A4, for example, oil is preliminarily contained in a web formed of heat-resistant fibers, and the oil is pressed while pressing the web against a heat fixing member. Means for supplying can be used.

The reaction mechanism between the surface oxidized carbon black particles dispersed in the surface of the fluoroelastomer and the dimethyl silicone oil having an unsaturated bond supplied from the outside to the surface of the heat fixing member is present on the surface of the carbon black particles. The hydrogen ions released from the oxygen-containing functional groups are added to the unsaturated bond part of the silicone oil, and the silicone oil to which the hydrogen ions are added reacts with the oxygen ions (—O ⁻ ) remaining on the surface of the carbon black particles. However, it is considered that a chemical bond is formed. Therefore, the outermost layer made of dimethyl silicone oil having an unsaturated bond on the surface of the fluoroelastomer can be formed through a chemical bond generated by an ionic reaction. Even when thousands or tens of thousands of sheets are passed through to fix toner images electrostatically formed on a recording material such as paper, the outermost silicone polymer may be detached from the fluoroelastomer layer due to abrasion. The dimethyl silicone oil having an unsaturated bond supplied from the outside is ionically reacted to the surface of the carbon black particle surface that has been exposed to oxidation and exposed to wear, and the outermost silicone polymer layer can be formed or repaired at all times. Therefore, a fixing device with high use durability can be realized.

The pH value of the surface-oxidized carbon black is preferably in the range of 2-4. Those less than 2 are difficult to obtain, and those exceeding 4 are low in the hydrogen ion concentration released, so that the ion reactivity with dimethyl silicone oil having an unsaturated bond is low, or the reaction amount is small. Absent. Further, the specific surface area (STSA) of the surface oxidized carbon black is preferably in the range of 50 to 400 m ² / g. If it is less than 50, the specific surface area is small, and sufficient reaction sites with dimethyl silicone oil having an unsaturated bond may not be obtained.

  Moreover, it is preferable that the compounding quantity of the surface-treated carbon black is in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the fluoropolymer that becomes a fluoroelastomer by crosslinking. If it is less than 0.1, it is not preferable because sufficient reaction sites with dimethyl silicone oil having an unsaturated bond may not be obtained. If it exceeds 5, the surface energy-like toner release property of the fluoroelastomer surface layer may be adversely affected, which is not preferable.

  Examples of the polymer species of the fluoroelastomer constituting the surface layer of the heat-fixing member of the present invention include, for example, vinylidene fluoride-based fluoropolymer, that is, a binary copolymer of vinylidene fluoride and hexafluoropropylene, or vinylidene fluoride and hexafluoro Fluoropolymers consisting of terpolymers of propylene and tetrafluoroethylene, or terpolymers of vinylidene fluoride, tetrafluoroethylene and perfluoroalkyl vinyl ethers can be mentioned. There is no radical crosslinking of a terpolymer (fluoropolymer) of vinylidene fluoride, tetrafluoroethylene and perfluoromethyl vinyl ether having at least one of iodine and bromine in the molecule. It is desirable to use a fluoroelastomer surface layer. Since this fluoroelastomer has a slightly lower surface energy than fluoroelastomers made of other polymer species, relatively good toner release properties can be obtained along with excellent flexibility, scratch resistance and abrasion resistance.

  Such a terpolymer of vinylidene fluoride having at least one of iodine and bromine in the molecule, tetrafluoroethylene, and perfluoromethyl vinyl ether can be synthesized by a known method. Such ternary copolymers are commercially available, for example, 'Daiel LT302' (manufactured by Daikin Industries), 'Viton GLT', 'Viton GLT-305', 'Viton GLT-505', Examples include “Viton GFLT”, “Viton GFLT-300”, “Viton GFLT-301”, “Viton GFLT-501”, and “Viton GFLT-600” (manufactured by DuPont Dow Elastomer Japan Co., Ltd.).

  The fluoropolymer desirably used in the present invention is of the type in which iodine or bromine is introduced into the molecular chain terminal or side chain, and the crosslinking is performed by an extraction reaction of iodine or bromine atoms. In the practice of the present invention, crosslinking is preferably performed using a crosslinking assistant and an organic peroxide that is a crosslinking agent.

  In forming the fluoroelastomer surface layer of the heat fixing member, first, a layer (fluoropolymer layer) in which at least a crosslinking agent, a crosslinking aid, and surface-oxidized carbon black are dispersed in the fluoropolymer is formed. It is preferable to make the surface of this fluoropolymer layer excellent in smoothness. Because the surface of the fluoropolymer layer almost determines the smoothness of the surface of the silicone polymer outermost layer formed on this surface. If the surface is not smooth, the surface irregularities are transferred to the image after fixing. This is because a high-quality toner-fixed image cannot be obtained.

  Since a heat source is placed inside the cylindrical base material, and the toner is softened by the heat and pressed onto the recording material, the fluoropolymer layer needs to be thin from the viewpoint of heat transfer from the cylindrical base material to the toner contact surface. There is. In addition, in a fixing device in which a heat source is arranged outside, it is preferable to form a thin fluoropolymer layer from the viewpoint of the heat capacity of the surface layer.

  When forming a layer having a thin layer and excellent surface smoothness, a coating method is suitable as a processing method. As a coating method, at least a fluoropolymer, a crosslinking agent, and a crosslinking aid are dissolved in an organic solvent, and surface-oxidized carbon black is dispersed in the same organic solvent to prepare a coating solution. This coating solution is uniformly applied on a cylindrical substrate by blade coating, ring coating, spray coating, dipping, etc. and dried, and at least a crosslinking agent, a crosslinking aid, and a surface oxidized carbon black in the fluoropolymer. Can be formed. However, when this coating method is used, when the atmospheric pressure hot-air crosslinking such as oven crosslinking is performed when the fluoropolymer layer is radically crosslinked, curing inhibition may occur due to oxygen in the air. If a liquid silicone polymer in a state, that is, 50 ° C. to 250 ° C. is brought into contact with each other for crosslinking, radical crosslinking can be performed without blocking oxygen and causing curing inhibition. In addition, if a terpolymer of vinylidene fluoride having at least one of iodine and bromine in the molecule, tetrafluoroethylene and perfluoromethyl vinyl ether is used as the fluoropolymer, the surface has some radical reactivity. The liquid silicone polymer reacts not only with the oxidized carbon black particle surface portion but also with the fluoroelastomer, so that the silicone polymer can be introduced by chemical bonding as the outermost layer, which is more preferable. As the bonding form, the surface layer side is the surface of carbon black particles subjected to surface oxidation treatment, and the part where iodine or bromine which is a radical crosslinking point of the fluoropolymer is released or the part of the vinyl group which is the radical reaction point of the crosslinking aid The liquid silicone polymer side has a large number of methyl group parts, or if the liquid silicone polymer has vinyl groups, the vinyl group part undergoes radical reaction and the surface oxidized carbon black particle surface and fluoroelastomer, and silicone It is thought that the polymer is chemically bonded. If the surface is not chemically bonded, the outermost silicone polymer is almost completely removed by wiping the surface of the fluoroelastomer with a solvent having affinity for the silicone polymer such as toluene. However, in the present invention, the surface of the carbon black particles whose surface is treated by oxidation of the silicone polymer, and vinylidene fluoride having at least one of iodine and bromine in the molecule as a polymer species, tetrafluoroethylene, and perfluoromethyl vinyl ether are used. When the original copolymer is used, since it is chemically bonded to the fluoroelastomer, it remains on the surface of the fluoroelastomer without being removed.

The radical reactivity and reaction amount of the surface oxidized carbon black particle surface and the liquid silicone polymer at the time of cross-linking the surface layer fluoropolymer are the specific surface area of the carbon black particle and the amount of oxygen-containing functional group present on the particle surface, that is, pH It changes by etc. Although the pH value cannot be generally stated, it is considered that the larger the specific surface area, the larger the amount of radical reaction. However, when surface-oxidized carbon black having a large amount of radical reaction, that is, surface-oxidized carbon black having a specific surface area (STSA) exceeding 400 m ² / g, is dispersed in the fluoropolymer, the cross-linked dispersed in the fluoropolymer. Since most of the agent reacts with carbon and has a great effect of inhibiting radical crosslinking of the fluoropolymer, it may not be possible to crosslink even if the amount of the crosslinking agent is increased.

  In addition, if a terpolymer of vinylidene fluoride having at least one of iodine and bromine in the molecule, tetrafluoroethylene and perfluoromethyl vinyl ether is used as a fluoropolymer species, as described above, a little radical reactivity is achieved. In addition to the surface oxidized carbon black particle surface portion, the liquid silicone polymer also undergoes a radical reaction with the fluoroelastomer, and the silicone polymer can be introduced by chemical bonding as the outermost layer. The reactivity at the interface between the fluoropolymer and the liquid silicone polymer is affected by the affinity between the two. That is, the higher the affinity, the higher the reactivity, and conversely, the lower the affinity, the lower the reactivity. For example, a fluoropolymer composed of a binary copolymer of vinylidene fluoride and hexafluoropropylene, which is generally used as a surface layer, or a terpolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, and a liquid silicone In the polymer, since the affinity between the two is too low, the radical reaction is difficult to occur, the cross-linking reaction of the fluoropolymer occurs preferentially on the surface portion of the surface layer, and the reaction between the fluoroelastomer and the silicone polymer hardly occurs. . However, the surface of the carbon black particles subjected to the surface oxidation treatment undergoes a radical reaction to form the outermost layer of the silicone polymer. However, fluoropolymers composed of terpolymers of vinylidene fluoride, tetrafluoroethylene, and perfluoromethyl vinyl ether, which are preferably used in the present invention, are less than silicone polymers compared to commonly used fluoropolymers. It is more desirable because the silicone polymer reacts with the fluoroelastomer as well as with the surface oxidized carbon black particle surface having a relatively high affinity and is introduced by chemical bonding.

The viscosity of the liquid silicone polymer used for radical cross-linking of the surface layer fluoroelastomer is not particularly limited, but is generally about 0.5 to 1,000,000 mm ² / s (25 ° C.) as commercially available. Yes, for the convenience of processing, 10 to 10,000 mm ² / s (25 ° C.) is preferable. The liquid silicone polymer is preferably a non-functional dimethyl silicone polymer or a dimethyl silicone polymer containing at least one vinyl group from the viewpoint of heat resistance. The chemical structure is more preferably a linear dimethyl silicone polymer or a linear dimethyl silicone polymer containing at least one vinyl group.

  Since one molecule of silicone polymer is considered to be present on the surface layer of the fluoroelastomer, the thickness of the outermost layer silicone polymer is considered to be about 1 to 100 nm, which is shorter than the chain length of the silicone polymer. The presence of the silicone polymer as the outermost layer on the fluoroelastomer surface layer makes it possible to obtain a heat-fixing member having a low surface energy and excellent toner release properties in the initial stage.

  By setting the total thickness of the fluoroelastomer surface layer and the silicone polymer outermost layer in the range of 5 to 100 μm, a heat-fixing member having excellent heat transfer to the toner contact surface can be obtained. When the thickness is less than 5 μm, the functions of the fluoroelastomer surface layer and the silicone polymer outermost layer may not be sufficiently exhibited. When the thickness exceeds 100 μm, heat transfer to the toner contact surface may deteriorate, which is not preferable.

  Examples of the crosslinking aid dispersed in the fluoropolymer layer include triallyl cyanurate and triallyl isocyanurate, and triallyl isocyanurate is particularly preferably used.

  Although the compounding quantity of this crosslinking adjuvant is not specifically limited, It is 0.5-10 weight part normally with respect to 100 weight part of fluoropolymer components, Preferably it is 1-5 weight part. However, when it is dissolved in a solvent and used as a coating solution as in the present invention, this amount may be used several times.

  Similarly, organic peroxides, which are crosslinking agents dispersed in the fluoropolymer layer, include benzoyl peroxide, bis (2,4-dichlorobenzoyl) peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di- (T-Butylperoxy) hexane can be mentioned, and benzoyl peroxide having a particularly low decomposition temperature is preferably used. Moreover, although a compounding quantity is not specifically limited, It is 0.5-10 weight part normally with respect to 100 weight part of fluoropolymer components, Preferably it is 1-5 weight part. However, when it is dissolved in a solvent and used as a coating solution as in the present invention, this amount may be used several times. If benzoyl peroxide is used as the cross-linking agent and the temperature of the heated liquid silicone polymer is set in the range of 110 ° C to 250 ° C, a sufficient amount of the silicone polymer outermost layer can be introduced onto the fluoroelastomer surface layer by chemical bonding. However, if the temperature of the liquid silicone polymer is lower than 110 ° C., which is the decomposition temperature of benzoyl peroxide, the fluoropolymer may not be radically crosslinked effectively, and if it is 250 ° C. or higher, the liquid silicone polymer will be thermally deteriorated. Inconvenience occurs.

  When coating a solution containing at least the fluoropolymer, crosslinking aid, crosslinking agent, and surface-oxidized carbon black, these are completely dissolved or dispersed in the solvent and remain dissolved or dispersed throughout the coating process. It is desirable that Suitable solvents include, for example, polar solvents such as methanol, acetone, methyl ethyl ketone and methyl isobutyl ketone, and dimethylformamide, dimethyl sulfoxide, N-methyl 2-pyrrolidone and the like, and it is particularly preferable to use methyl isobutyl ketone. The solvent is preferably added so that the total solid component concentration is 5 to 40% by weight, preferably 10 to 30% by weight.

  As a manufacturing method of the heat fixing member of the present invention, for example, the following steps can be shown. Fluoropolymer consisting of terpolymer of vinylidene fluoride containing tetraiodine and tetrafluoroethylene containing iodine in the molecule, triallyl isocyanurate as crosslinking aid, benzoyl peroxide as crosslinking agent as solvent The carbon black dissolved in methyl isobutyl ketone and further surface-oxidized is dispersed in the same solvent by stirring with glass beads or the like to prepare a coating solution. Next, a cylindrical base material (a metal roller base material on which a heat-resistant elastic body layer is formed in advance, or a metal or resin belt base material) on which a primer is uniformly applied and dried in advance is fixed horizontally, While rotating, the coating solution is uniformly applied to the outer periphery of the cylindrical substrate. After a desired amount is applied, it is allowed to stand at room temperature at a constant rotational speed and leveled while evaporating the solvent to some extent. Then, it is dried at 50 ° C. for 2 hours and immersed in a liquid silicone polymer heated to 200 ° C. for 1 hour to perform primary crosslinking, so that no inhibition of curing by oxygen occurs, and as the outermost layer on the fluoroelastomer surface layer. Silicone polymer layers can be introduced by chemical bonding. After the primary cross-linking, the heat-fixing member can be produced by taking out the liquid silicone polymer and performing the secondary cross-linking in a heating oven.

  FIG. 1 shows a cross-sectional view of a fixing roller which is one form of the heat-fixing member thus obtained, and FIG. 2 shows a cross-sectional view of a fixing belt which is another form. In FIG. 1, 1 is a roller base material made of metal such as aluminum, 2 is an elastic body layer having heat resistance and heat conductivity made of conventional silicone rubber, 3 is a surface layer made of fluoroelastomer, and 4 is made of silicone polymer. It is the outermost layer. In FIG. 2, 5 is a metal or resin belt substrate, 2 is a heat-resistant and heat-conductive elastic layer made of conventional silicone rubber, 3 is a surface layer made of fluoroelastomer, and 4 is a top layer made of silicone polymer. It is a surface layer. The heat-fixing member of the present invention is not limited to the above four-layer structure, but has a three-layer structure without heat-resistant and heat-conductive elastic layers made of silicone rubber or the like, or five or more layers. Although a multilayer structure may be used, a four-layer structure is preferable in terms of the function as a heat fixing member.

  Next, the fixing device of the present invention will be described. The fixing device of the present invention is a fixing device used in an electrophotographic image forming apparatus, and is provided with at least a heating fixing member as described above and a supply means for supplying dimethyl silicone oil having an unsaturated bond. is there. As an electrophotographic image forming apparatus, a photosensitive member, a latent image forming means, a means for developing the formed latent image with toner, a means for transferring the developed toner image to a transfer material, and a toner image on the transfer material are fixed. An electrophotographic image forming apparatus having means and the like can be mentioned.

  An example of the fixing device of the present invention is shown in FIG. In the fixing device, a fixing roller 6 and a pressure belt 7 which are one form of a heat fixing member are arranged. A halogen heater 8 is incorporated inside the fixing roller 6.

  The fixing roller 6 is rotationally driven in the arrow direction at a predetermined peripheral speed, and the pressure belt 7 is also rotationally driven in the arrow direction accordingly. Then, the recording material 9 such as paper or an OHP sheet is conveyed in the direction of the arrow. When the color unfixed toner image 10 passes through the nip formed between the fixing roller 6 and the pressure belt 7, heat from the halogen heater 8 and pressure between the fixing roller 6 and the pressure belt 7 are applied. And fixed on the recording material 15.

  The fixing temperature is maintained at a set temperature by controlling the output of the halogen heater 8 based on the temperature measured by the thermistor 11 on the surface temperature of the fixing roller 6. The surface temperature (fixing temperature) of the fixing roller 6 is not particularly limited, but is usually about 130 to 250 ° C., and is set to 190 ° C. in this embodiment.

The fixing roller 6 is arranged so that dimethyl silicone oil having an unsaturated bond is applied and a web unit 12 made of heat-resistant fibers for cleaning dirt such as toner adhering to the surface of the fixing roller 6 is in contact therewith. ing.
The viscosity of the dimethyl silicone oil having an unsaturated bond at 25 ° C. is preferably in the range of 100 to 20000 mm ² / s. When the viscosity is less than 100 mm ² / s, the viscosity is too low, so that it is difficult to hold the oil in the web unit 12, and the oil immediately moves to the surface of the heat fixing member. May be difficult and is not preferred. On the other hand, when the viscosity exceeds 20000 mm ² / s, the viscosity is too high and it is difficult to apply the oil to the surface of the heat fixing member. In the examples of the present invention, dimethyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.) having a linear shape of 400 mm ² / s (25 ° C.) and having vinyl groups at both ends was used.

In this embodiment, the web unit 12 is configured and adjusted so that the amount of oil applied to the surface of the fixing roller 6 is about 0.2 mg / 621 cm ² (equivalent to A4).

  The web unit 12 is coated with a dimethyl silicone oil having an unsaturated bond and cleans dirt such as toner, and the web 13 is elastically pressed against the surface of the fixing roller 6 which is one form of a heat fixing member. The body roller 14 is used. The web 13 made of heat-resistant fibers is wound up little by little in the direction of the arrow.

  Inside the pressure belt, a roller 15 for securing the nip and a roller 16 for separating the recording material are arranged.

  FIG. 4 shows a configuration diagram of another example of the fixing device of the present invention. The fixing device 2 is provided with a fixing belt 17 and a pressure roller 18 which are one form of a heat fixing member. A heating element (ceramic heater) 19, a belt guide member 20 that supports the heating element 19 and guides the movement of the fixing belt 17, and the fixing belt 17 are pressed against the web 13 inside the fixing belt 17. The roller 21 is arranged.

  The pressure roller 18 is rotationally driven in the direction of the arrow at a predetermined peripheral speed, and the fixing belt 17 is also rotationally driven in the direction of the arrow accordingly. Then, the recording material 9 such as paper or an OHP sheet is conveyed in the direction of the arrow. When the color unfixed toner image 10 passes through the nip formed between the fixing belt 17 and the pressure roller 18, heat from the heating element 19 and pressure between the fixing belt 17 and the pressure roller 18 are applied. And fixed on the recording material 9.

  The fixing temperature is maintained at a set temperature by controlling the output of the heating element 19 based on the temperature measured by the thermistor 11 on the surface temperature of the fixing belt 17. The surface temperature (fixing temperature) of the fixing belt 17 is not particularly limited, but is usually about 130 to 220 ° C., and is set to 180 ° C. in this embodiment.

  A web made of heat-resistant fibers for applying a dimethyl silicone oil having an unsaturated bond to the fixing belt 17 which is one form of the heat fixing member and cleaning dirt such as toner adhering to the surface of the fixing belt 17. The units 12 are arranged so as to contact each other.

  The fixing device of the present invention only needs to have a roller-shaped or belt-shaped heat fixing member and means for supplying dimethyl silicone oil having an unsaturated bond on the surface of the heat fixing member. It is not limited to what is shown.

  In the embodiment of the present invention, the durability of the fixing device is evaluated by passing up to 100,000 sheets of unfixed color toner image 10 (produced using CLC900 manufactured by Canon Inc.) formed on the recording material 9. Whether or not a toner offset occurs in the image after fixing was evaluated based on the number of toner offset occurrences.

  The present invention will be described in more detail below by way of examples, but these examples do not limit the present invention in any way. Unless otherwise specified, commercially available high-purity products were used as reagents. Further, the ten-point average surface roughness (Rz) was measured according to JIS B 0601.

(Example 1)
Fluoropolymer (trade name: Daiel LT302, manufactured by Daikin Industries, Ltd.) made of a terpolymer of vinylidene fluoride containing iodine in the molecule, tetrafluoroethylene and perfluoromethyl vinyl ether, and average particle Surface oxidized carbon black (Raven 5750 Powder, Columbian Chemicals, Inc.) having a diameter of 12 nm, a specific surface area (STSA) of 294 m ² / g, a pH of 2.1, and a volatile content during heating of 9.5% 1 part by mass), 4 parts by mass of benzoyl peroxide (25% water-containing product, manufactured by Kishida Chemical Co., Ltd.) as a crosslinking agent, and triallyl isocyanurate (trade name: TAIC, Nippon Kasei) as a crosslinking aid 4 parts by mass dissolved in methyl isobutyl ketone as a solvent so that the polymer component concentration is 25% by mass. Alternatively, it was dispersed to prepare a coating solution of fluoropolymer.

  Next, an elastic body layer made of heat-resistant silicone rubber having a thickness of 2 mm was formed on a metal roller made of aluminum (outer diameter: 58 mm, inner diameter: 34 mm) via a primer.

  Irradiate the surface of this silicone rubber layer with ultraviolet rays (UV irradiation device, manufactured by Harrison Toshiba Lighting Co., Ltd.), and then fix the roller horizontally and rotate the alcoholic solution of aminosilane compound (MEGUM 3290, manufactured by Chemetall). Apply uniformly by spray coating, apply the desired amount, leave it at room temperature for 30 minutes at room temperature, evaporate the solvent to form an adhesive layer with a thickness of about 1 μm, and fluoropolymer coating solution A layer (barrier layer) for preventing the transfer of the crosslinking agent and the crosslinking aid into the silicone rubber layer was formed.

  Next, the roller on which the layer having the adhesion and crosslinking agent / crosslinking aid barrier function was formed was fixed horizontally, and the fluoropolymer coating solution prepared while rotating was uniformly applied to the outer periphery of the roller by blade coating. . After applying a desired amount, it was allowed to stand at room temperature at a constant roller rotation number and leveled while evaporating the solvent to some extent.

Then, it was dried at 50 ° C. for 2 hours and heated to 200 ° C. for 1 hour in a liquid dimethyl silicone polymer (trade name: KF-96SS-300cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 300 mm ² / s (25 ° C.). After immersion, primary crosslinking is performed, and then the liquid silicone polymer is taken out. Excess liquid silicone polymer present on the roller surface is removed with toluene, and then secondary crosslinking is performed at 180 ° C. for 24 hours in an oven. The fixing roller 1 in the form was produced.

  The ten-point average surface roughness Rz of the outermost silicone polymer layer of this roller was 1 μm or less, and the total thickness of the fluoroelastomer surface layer and the outermost silicone polymer layer was 50 μm.

Even if the surface of the fixing roller 1 was wiped with a cloth impregnated with methyl ethyl ketone, the gloss did not disappear, so that it was confirmed that the crosslinking reaction proceeded without inhibiting the curing by oxygen. Further, since the wettability of dimethyl silicone oil (trade name: KF-96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 100 mm ² / s (25 ° C.) with respect to the surface of the fixing roller is good, It was confirmed that the surface layer was chemically bonded to the fluoroelastomer surface layer.

[Initial evaluation example]
The fluoropolymer coating solution was uniformly applied to a thickness of 50 μm after drying on an aluminum plate, allowed to stand at room temperature, the solvent was evaporated to some extent, and dried in an oven at 50 ° C. for 2 hours. It is immersed in a liquid dimethyl silicone polymer (trade name: KF-96SS-300cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 300 mm ² / s (25 ° C.) heated to 200 ° C. for 1 hour, followed by primary crosslinking. The sample was taken out from the liquid silicone polymer, and after removing excessive liquid silicone polymer on the surface with toluene, secondary crosslinking was performed in an oven (normal pressure hot air) at 180 ° C. for 24 hours to prepare a sample. The ten-point average surface roughness of this sample was 1 μm or less.

  Even if the surface of this sample was wiped with a cloth impregnated with methyl ethyl ketone, the gloss did not disappear, so that it was confirmed that the crosslinking reaction proceeded without inhibiting the curing by oxygen.

  Moreover, as a result of performing elemental analysis by ESCA on the outermost surface of the sample (analyzer name: Quantum 2000, ULVAC-PHI Co., Ltd.), it was found that a large amount of Si element was present and a silicone polymer was present. From this, it was confirmed that the silicone polymer outermost layer was formed by chemical bonding. However, elemental analysis by SEM (analyzer name: JSM-5800LV type, manufactured by Nippon Philips Co., Ltd., EPMA: DX-Prime type manufactured by Nippon Philips Co., Ltd.) did not detect Si element.

Since the detection range in the depth direction was not detected by elemental analysis by SEM having a micron order, but was detected by elemental analysis by ESCA being nano order, the outermost silicone polymer layer was in the submicron to nano order range. It turned out to be thickness. The contact angle of dimethyl silicone oil (trade name: KF-96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 100 mm ² / s (25 ° C.) with respect to the sample surface was measured at room temperature (25 ° C.). It was 5 ° or less, and it was found that the wettability of the silicone oil was good.

[Durability evaluation]
The produced fixing roller 1 was placed in the fixing device 1 shown in FIG. Through this fixing device, up to 100,000 unfixed color toner images 10 formed on the recording material 9 are passed, and whether or not a toner offset occurs in the image after fixing is evaluated by the number of generated toner offsets. did.

(Example 2)
Carbon black (Raven 3500 Powder, Columbian Chemicals, Inc.) having an average particle size of 13 nm, a specific surface area (STSA) of 223 m ² / g, a pH of 2.5, and a volatile content during heating of 5%. A fixing roller 2 was produced in the same manner as in Example 1 except that 1 part by mass of (manufactured by Company) was blended.

Even when the surface of the fixing roller 2 was wiped with a cloth impregnated with methyl ethyl ketone, the gloss did not disappear, so that it was confirmed that the crosslinking reaction proceeded without inhibiting the curing by oxygen. Further, since the wettability of dimethyl silicone oil (trade name: KF-96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 100 mm ² / s (25 ° C.) with respect to the roller surface is good, the outermost layer of the silicone polymer is It was confirmed that it was chemically bonded to the fluoroelastomer surface layer.

[Durability evaluation]
The produced fixing roller 2 was placed in the fixing device 1 shown in FIG. Through this fixing device, up to 100,000 unfixed color toner images 10 formed on the recording material 9 are passed, and whether or not a toner offset occurs in the image after fixing is evaluated by the number of generated toner offsets. did.

(Example 3)
Surface-oxidized carbon black (Raven 1255 Powder, Colombian, with an average particle size of 21 nm, a specific surface area (STSA) of 115 m ² / g, a pH of 2.5, and a volatile content of 2.7% during heating. A fixing roller 3 was produced in the same manner as in Example 1 except that 2 parts by mass of Chemicals Company) was added.

Even when the surface of the fixing roller 3 was wiped with a cloth impregnated with methyl ethyl ketone, the gloss did not disappear, so that it was confirmed that the crosslinking reaction proceeded without inhibiting curing by oxygen. Further, since the wettability of dimethyl silicone oil (trade name: KF-96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 100 mm ² / s (25 ° C.) with respect to the roller surface is good, the outermost layer of the silicone polymer is It was confirmed that it was chemically bonded to the fluoroelastomer surface layer.

[Durability evaluation]
The produced fixing roller 3 was placed in the fixing device 1 shown in FIG. Through this fixing device, up to 100,000 unfixed color toner images 10 formed on the recording material 9 are passed, and whether or not a toner offset occurs in the image after fixing is evaluated by the number of generated toner offsets. did.

Example 4
Surface-oxidized carbon black (Raven 1060 Powder, Colombian, with an average particle size of 30 nm, specific surface area (STSA) of 65 m ² / g, pH of 2.4, and volatile content during heating of 1.6% A fixing roller 4 was produced in the same manner as in Example 1 except that 4 parts by mass of Chemicals Company) was added.

Even when the surface of the fixing roller 4 was wiped with a cloth impregnated with methyl ethyl ketone, the gloss did not disappear, so that it was confirmed that the crosslinking reaction proceeded without inhibiting curing by oxygen. Further, since the wettability of dimethyl silicone oil (trade name: KF-96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 100 mm ² / s (25 ° C.) with respect to the roller surface is good, the outermost layer of the silicone polymer is It was confirmed that it was chemically bonded to the fluoroelastomer surface layer.

[Durability evaluation]
The produced fixing roller 4 was arranged in the fixing device 1 shown in FIG. Through this fixing device, up to 100,000 unfixed color toner images 10 formed on the recording material 9 are passed, and whether or not a toner offset occurs in the image after fixing is evaluated by the number of generated toner offsets. did.

(Example 5)
Except for using 100 parts by mass of a fluoropolymer (trade name: Daiel G902, manufactured by Daikin Industries, Ltd.) consisting of a terpolymer of vinylidene fluoride containing iodine in the molecule, hexafluoropropylene and tetrafluoroethylene. In the same manner as in Example 1, a fixing roller 5 was produced.

Even when the surface of the fixing roller 5 was wiped with a cloth impregnated with methyl ethyl ketone, the gloss did not disappear. Therefore, it was confirmed that the crosslinking reaction proceeded without inhibiting the curing by oxygen. Further, since the wettability of dimethyl silicone oil (trade name: KF-96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 100 mm ² / s (25 ° C.) with respect to the roller surface is relatively good, It was confirmed that the surface layer was chemically bonded to the surface oxidized carbon black particle surface in the fluoroelastomer surface layer.

[Durability evaluation]
The produced fixing roller 5 was placed in the fixing device 1 shown in FIG. Through this fixing device, up to 100,000 unfixed color toner images 10 formed on the recording material 9 are passed, and whether or not a toner offset occurs in the image after fixing is evaluated by the number of generated toner offsets. did.

(Example 6)
First, a heat-resistant silicone rubber layer having a thickness of 200 μm was formed on a polyimide belt base material (outer diameter: 29.8 mm) having a thickness of 50 μm that had been subjected to primer treatment on the outer peripheral surface. Next, the surface of the silicone rubber layer is irradiated with ultraviolet rays (UV irradiation device, manufactured by Harrison Toshiba Lighting Co., Ltd.), and then the belt is fixed horizontally and the alcoholic solution of the aminosilane compound (MEGUM 3290, Chemetall) while rotating. The product is uniformly applied by spray coating, and after applying the desired amount, it is allowed to stand at room temperature for 30 minutes at a constant number of revolutions, and the solvent is evaporated to bond the adhesive with a thickness of about 1 μm and a crosslinking agent / crosslinking aid. A layer having an agent barrier function was formed.

The fluoropolymer coating solution prepared in Example 4 was uniformly applied to the outer periphery of the belt by blade coating while the belt on which the layer having the adhesion and barrier function was formed was fixed horizontally and rotated. After applying a desired amount, it was allowed to stand at room temperature at a constant rotational speed and leveled while evaporating the solvent to some extent. Thereafter, it was dried at 50 ° C. for 2 hours and immersed in a liquid dimethyl silicone polymer having a viscosity of 300 mm ² / s heated to 200 ° C. (trade name: KF-96SS-300cs, manufactured by Shin-Etsu Chemical Co., Ltd.) for 1 hour. After the primary crosslinking, the liquid silicone polymer is taken out from the liquid, and the liquid silicone polymer that is excessively present on the belt surface is removed with toluene, followed by secondary crosslinking in an oven (atmospheric pressure hot air) at 180 ° C. for 24 hours. 1 was produced.

  The ten-point average surface roughness of the outermost silicone polymer layer of this belt was 1 μm or less, and the total thickness of the fluoroelastomer surface layer and the outermost silicone polymer layer was 50 μm.

Further, even when the surface of the fixing belt 1 obtained with the cloth impregnated with methyl ethyl ketone was wiped off, the gloss did not disappear, so that it was confirmed that the crosslinking reaction proceeded without inhibiting curing by oxygen. Moreover, since the wettability of the dimethyl silicone oil (trade name: KF-96-100cs, manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 100 mm ² / s (25 ° C.) with respect to the belt surface is good, the outermost layer of the silicone polymer Was confirmed to be chemically bonded to the surface layer of the fluoroelastomer.

[Durability evaluation]
The produced fixing belt 1 was placed in the fixing device 2 shown in FIG. Through this fixing device, up to 100,000 unfixed color toner images 10 formed on the recording material 9 are passed, and whether or not a toner offset occurs in the image after fixing is evaluated by the number of generated toner offsets. did.

(Comparative Example 1)
A fixing roller 6 was prepared in the same manner as in Example 1 except that 4 parts by mass of medium thermal carbon black (Thermax N-990, manufactured by Cancarlb Ltd.) was blended as the carbon black, and this fixing roller 6 was disposed. The durability of the fixing device was evaluated in the same manner as in Example 1.

(Comparative Example 2)
The fixing roller 4 produced in Example 4 is placed in the fixing device 1 shown in FIG. 3, and a non-functional dimethyl silicone oil (KF96-300cs, Shin-Etsu Chemical Co., Ltd.) which does not have an unsaturated bond with a silicone oil pre-impregnated into the web. The durability of the fixing device was evaluated in the same manner as in Example 4 except that the product was manufactured by Kogyo Co., Ltd.

(Comparative Example 3)
A fixing belt 2 was prepared in the same manner as in Example 6 except that 4 parts by mass of medium thermal carbon black (Thermax N-990, manufactured by Cancarlb Ltd.) was blended as carbon black, and this fixing belt 2 was disposed. The durability of the fixing device was evaluated in the same manner as in Example 6.

(Comparative Example 4)
The fixing belt 1 produced in Example 6 is placed in the fixing device 2 shown in FIG. 4, and a non-functional dimethyl silicone oil (KF-96SS-300cs, which has no unsaturated bond) is preliminarily impregnated into the web. The durability of the fixing device was evaluated in the same manner as in Example 6 except that Shin-Etsu Chemical Co., Ltd. was used.

  Table 1 shows the evaluation results of the durability of the fixing devices of Examples 1 to 6 and Comparative Examples 1 to 4.

  From Table 1, carbon black subjected to surface oxidation treatment was dispersed in the surface layer of the fluoroelastomer in the heat fixing members of Examples 1 to 6, and fixing having means for applying silicone oil having an unsaturated bond to the surface of the heat fixing member. It can be seen that the apparatus does not generate toner offset even when 100,000 unfixed color toner images are passed, and has high durability. This is because even if the outermost silicone polymer present on the surface layer of the initial fluoroelastomer wears, the surface of the oxidized carbon black particles exposed to the surface reacts with the dimethyl silicone oil having an unsaturated bond, This is probably because the outermost layer of the silicone polymer is always formed or repaired.

  On the other hand, even if carbon black subjected to surface oxidation treatment is dispersed in the surface of the fluoroelastomer in the heat fixing members of Comparative Examples 1 and 3, means for applying non-functional dimethyl silicone oil to the surface of the heat fixing member In the fixing device having toner, toner offset occurred when 10,000 unfixed color toner images were passed. This is because the non-functional dimethyl silicone oil does not react with the surface oxidized carbon black particle surface, and when the outermost layer silicone polymer present at the initial stage wears, the outermost layer is not formed again, and 10,000 sheets are passed. It is thought that sometimes toner offset occurred.

  Further, medium thermal carbon (MT carbon) not subjected to surface oxidation treatment is dispersed in the surface of the fluoroelastomer in the heat fixing member of Comparative Examples 2 and 4, and a silicone oil having an unsaturated bond is applied to the surface of the heat fixing member. In the fixing apparatus having the means, a toner offset occurs when 20,000 unfixed color toner images are passed. This is because dimethyl silicone oil having an unsaturated bond reacts slightly with the surface fluoroelastomer, but does not react with the surface of the MT carbon particles, so that it is considered that toner offset occurred when 20,000 sheets were passed. .

  For the fixing devices of Examples 1 to 6, high-quality color fixed images were obtained even at the initial stage and when 100,000 unfixed color toner images were passed.

It is sectional drawing of the fixing roller which is one form of the heat fixing member in connection with this invention. 1 is a cross-sectional view of a fixing belt which is an embodiment of a heat fixing member according to the present invention. 1 is a configuration diagram of a fixing device 1 according to the present invention. 1 is a configuration diagram of a fixing device 2 according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Roller base material 2 Heat resistant elastic body layer 3 Fluoroelastomer surface layer 4 Silicone polymer outermost layer 5 Belt base material 6 Fixing roller 7 Pressure belt 8 Halogen heater 9 Recording material 10 Color unfixed toner image 11 Thermistor 12 Web unit 13 Web 14 Elastic roller 15 Roller 16 Roller 17 Fixing belt 18 Pressure roller 19 Heating element 20 Belt guide member 21 Roller

Claims (13)

  In a fixing device having a heat fixing member and a pressure fixing member pressed against the heat fixing member, the heat fixing member includes at least a fluoroelastomer surface layer in which carbon black subjected to surface oxidation treatment is dispersed, A fixing device comprising oil supply means for applying dimethyl silicone oil having an unsaturated bond to a surface of a fixing member.   The fixing device according to claim 1, wherein the surface-oxidized carbon black has a pH value in a range of 2 to 4. 5. The fixing device according to claim 1, wherein the surface oxidized carbon black has a specific surface area (STSA) in a range of 50 to 400 m ² / g.   The amount of the carbon black subjected to the surface oxidation treatment is in a range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the fluoropolymer that becomes a fluoroelastomer by crosslinking. Fixing device.   2. The fixing device according to claim 1, wherein the dimethyl silicone oil having an unsaturated bond is a dimethyl silicone oil having at least one vinyl group in a molecule. The fixing device according to claim 1, wherein the viscosity of the dimethyl silicone oil having at least one vinyl group in the molecule is in a range of 100 to 20000 mm ² / s (25 ° C.).   2. The fixing device according to claim 1, wherein the supply amount of the oil supply means is in an average range of 0.01 to 1 mg per area corresponding to one A4 sheet.   The oil supply means includes a dimethyl silicone oil having the unsaturated bond previously contained in a web formed of heat-resistant fibers, and supplies oil while the web is pressed against the heat fixing member. The fixing device according to claim 7.   The surface fluoroelastomer of the heat-fixing member radically crosslinks a fluoropolymer comprising a terpolymer of vinylidene fluoride having at least one of iodine and bromine in the molecule, tetrafluoroethylene, and perfluoromethyl vinyl ether. The fixing device according to claim 1, wherein the fixing device is formed as described above.   The fixing device according to claim 1, comprising a fluoroelastomer surface layer according to claim 9, and an outermost layer formed on the surface layer by chemically bonding a liquid silicone polymer to the fluoroelastomer. .   The heat fixing member is composed of a cylindrical base material, a base layer made of a silicone rubber having heat resistance and heat conductivity, a surface layer made of a fluoroelastomer, and an outermost layer made of a silicone polymer. The fixing device according to claim 1 or 10, wherein the total thickness of the outermost polymer layer is in the range of 5 to 100 µm.   The fixing device according to claim 1, wherein the heat fixing member has a roller shape.   The fixing device according to claim 1, wherein the heat fixing member has a belt shape.

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