JP2005292578A - Belt-type fixing device, image forming method, and imaging forming material thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which realizes superior image quality by enhancing glossiness reduced by ruggedness of a toner image formed on a recording medium, to a level equivalent to that of a silver salt photograph to give uniform glossiness, irrespective of whether the toner density is high or low. <P>SOLUTION: The belt type fixing device has a metallic belt 1 stretched on a heat roller 2 and a cooling roller 4 and rotationally driven by two shafts of the rollers 2 and 4 and has a heating/pressurizing mechanism, in which a pressure roller pressurizes the heat roller from the outer peripheral side of the metallic belt being around the heat roller; and a cooling mechanism, in which a cooling member 8 is provided between the heat roller and the cooling roller so as to be brought into contact with the inside surface of the metallic belt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner fixing device, an image forming method, and a method for forming a toner image formed by electrophotography applied to a color copying machine, a color printer, or the like, and providing color reproducibility and glossiness equivalent to silver salt photography The present invention relates to an image forming body.

  2. Description of the Related Art Conventionally, in an electrophotographic copying machine and printer, image input / output has been digitized, and high image quality as digital photo output has been studied. In electrophotography applied to a color copying machine or a color printer, an image is formed with color toner. In general, a color toner is produced by kneading a dye or pigment or other additives in a thermoplastic resin, and pulverizing it to a diameter of 5 to 20 μm. In a full color image forming method by electrophotography, color toner images for each color of Y (yellow), M (magenta), C (cyan), and BK (black) are transferred onto a recording medium and superimposed. The toner images superimposed on the recording medium are heated and fixed by a heat roller fixing device to form a full color image.

  The color toner of four colors forms irregularities on the surface of the recording medium after heat fixing, and the step difference between the part where all color toners are superimposed and the part where no toner is present reaches as much as 30 μm. In addition, unevenness of about 6 to 8 μm is produced in the halftone image. A toner image having such irregularities is poor in gloss as compared with a silver salt photograph, and the color reproducibility is inferior due to scattering of reflected light by the irregularities, so that a photographic color image quality cannot be obtained.

  On the other hand, in order to improve the color image quality of the toner image, a toner image is formed on a recording medium having a thermoplastic resin layer on a substrate, and the toner image together with the recording medium is heated on a belt-like smooth carrier. An image forming method has been proposed in which a toner image is embedded in a thermoplastic resin layer to eliminate the unevenness by performing thermocompression bonding with a roller.

  For example, a method has been proposed in which toner is electrostatically transferred onto a recording medium provided with a thermoplastic resin having a film thickness of 20 to 200 μm, and is thermocompression bonded with a belt-like fixing machine to embed the toner image in the thermoplastic resin layer. (Patent Document 1). The belt used here is a heat-resistant belt made of a resin in which the surface of a heat-resistant resin such as polyimide is treated with a silicone resin. In cooling after the toner image is thermocompression bonded to the recording medium, the belt surface, the recording medium, and the toner image And releasability is good. However, the toner resin described in Patent Document 1 and the thermoplastic resin on the surface of the recording medium have insufficient compatibility between the toner resin melted at the time of thermocompression bonding and the thermoplastic resin, and some toner irregularities are formed on the surface of the thermoplastic resin. Produce. On the other hand, the belt is deformed by stretching due to the unevenness of the toner. Also, the end of the recording medium causes deformation of the belt according to the thickness of the recording medium, so that the smoothness of the belt surface is gradually lost. Further, when foreign matter adheres to the heating roller, small protrusions are likely to be formed on the belt surface, and at the time of thermocompression bonding, a dent derived from the protrusions on the belt surface is generated on the surface of the toner image and the thermoplastic resin on the recording medium. Furthermore, since the belt is made of resin, the surface of the belt is likely to be scratched by repeated use. As described above, the protrusions and scratches on the belt surface are transferred to the toner image and the recording medium as dents and streaks, so that the toner image is seriously damaged. In Patent Document 1, although the toner is embedded in the resin layer immediately after heat fixing and exhibits an extremely smooth glossiness, the unevenness due to the toner and paper base fiber is exposed due to the influence of subsequent aging and moisture. Or has a disadvantage of loss of gloss.

  Further, methods other than the belt-type fixing method have been proposed as an image forming method in which a toner image is embedded in a thermoplastic resin layer to eliminate unevenness. For example, a toner image is formed on a recording medium in which a thermoplastic resin that softens at the melting temperature of the toner binder resin and has a good compatibility with the toner binder resin is provided on a substrate, and rubber There has been proposed a method in which a toner image and a recording medium are directly heat-pressed with a heating roller and a pressure roller whose surface is covered with a fluorine-based rubber having a hardness of 60 degrees, and the toner is embedded in a thermoplastic resin layer (Patent Document 2). . According to this method, the toner is sufficiently embedded in the thermoplastic resin layer to flatten the toner image, and the surface gloss is uniform regardless of the toner density. However, generally, if the heating roller is not a glossy surface such as a mirror surface, the glossiness of a silver salt photograph, for example, a glossiness of at least 50 to 60% at a 20 degree glossiness cannot be obtained, and a photographic image is obtained. Not up to.

  For example, a belt-like toner image obtained by electrostatically transferring a toner image using a recording medium having a softening point in the range of + 10 ° C. to −30 ° C. relative to the softening point of the toner as a thermoplastic resin on the recording medium. There has been proposed a method in which a holding body and the recording medium are brought into close contact with each other and thermocompression bonding is performed with a heating roll and a pressure roll through a toner image holding body (Patent Document 3). According to Patent Document 3, this toner image holding member is provided with an elastic layer made of a silicone copolymer as a surface layer on a polyimide film having a thickness of 70 μm to which carbon black has been added. Also in this case, high glossiness like silver salt photography cannot be obtained for the same reason as in Patent Document 2.

  Also, in the printing industry, for the purpose of glossy finishing of printed matter, a conventional stainless steel mirror endless belt is stretched around two axes, a heating roller and a cooling roller. A processing method is employed in which a printed material coated with a resin is subjected to thermocompression bonding, and the printed material is separated from the belt at a cooling roll position. For example, this corresponds to an endless press process of press coat processing for gloss finish of printed matter. The present inventors conducted a thermocompression test on the toner image in this endless press process, but the surface roughness of the stainless steel belt was large, and glossiness equivalent to that of a silver salt photograph could not be obtained. The endless press itself is a large industrial machine that usually has a length of several meters, a width of 1 meter, and a roll diameter of 200 mm. It cannot be introduced as an accessory of an electrophotographic apparatus used in an office or a digital minilab.

JP-A-5-216322 Japanese Patent Laid-Open No. 10-221877 JP 2001-117387 A

  The present invention has been made in view of the above-described problems, and its purpose is to increase the glossiness reduced by the unevenness of the toner image formed on the recording medium to the same level as that of a silver salt photograph, thereby increasing the toner density. Regardless, it gives uniform gloss. In addition, the color reproducibility lowered by scattering of the reflected light due to the unevenness of the toner is raised to the same level as that of the silver salt photograph. Also, a fixing device that realizes excellent image quality with high gloss and high color by preventing deformation and scratches of the belt that can occur in the resin belt fixing method, and deterioration of image quality such as dents and streaks caused by the deformation, An image forming method and an image forming body thereof are provided.

  The belt-type fixing device of the present invention is a heating / pressurizing device in which a metal belt is stretched around two axes of a heating roller and a cooling roller and driven to rotate, and the pressure roller is pressed from the outer peripheral side of the metal belt surrounding the heating roller. And a cooling mechanism provided with a cooling member so as to be in contact with the inner surface of the metal belt between the heating roller and the cooling roller.

  Also, the image forming method of the present invention comprises forming a toner image on a resin surface of a recording medium having a thermoplastic resin layer on a substrate, and forming the toner image on a metal belt surface of the belt-type fixing device. Including the step of embedding the toner image in a thermoplastic resin layer by thermally pressing the toner image on the surface of the recording medium by passing between the heating roller and the pressure roller while keeping the medium in close contact, The recording medium on which the toner image on the surface of the recording medium is thermocompression bonded is moved to the cooling roller position while being held in close contact with the metal belt, and the toner image and the surface of the recording medium are moved by the cooling roller through the metal belt. And a step of separating the recording medium on which the flat toner image is formed from the metal belt by cooling.

In the image forming method, the recording medium has a shape anisotropy on a paper substrate, has an aspect ratio of 1 or more, and has a BET specific surface area of 100 to 180 m ² / g, and γ-alumina produced by a vapor phase method. 1 to 30 g / m ^{2 is} applied as a solid content and dried, and then an aqueous emulsion containing a thermoplastic resin as a solid content is applied 1 to 30 g / m ² and heated. More preferred is a toner image forming method in which a thermoplastic resin surface is pressure-bonded to a metallic mirror surface, dried and melted, and then solidified and peeled.

  Furthermore, in the above-described belt type fixing device, a belt type fixing device in which the diameters of the heating roller and the cooling roller are 50 mm to 150 mm is more preferable. Furthermore, the cooling member is more preferably a belt-type fixing device that is any member of a cooling water tank, a cooling roll, and a cooling fan. Further, a belt-type fixing device having a thickness of 0.05 mm to 0.30 mm is more preferable. Furthermore, the metal belt is more preferably a belt-type fixing device having a diameter of 150 mm to 310 mm. Further, a belt type fixing device in which the metal belt is a stainless steel belt having a mirror surface with a ten-point average roughness Rz of 0.2 μm or less and a center line average roughness Ra of 0.035 μm or less is more preferable. Further, the metal belt is more preferably a belt type fixing device which is a stainless steel belt having a Vickers hardness Hv of 430 to 500.

Further, in the metal belt, any of nitrogen ions, fluorine ions, and carbon ions is implanted at a depth of 10 ¹⁰ to 10 ²⁰ ions from the surface to a depth of 1000 mm with respect to the entire outer surface of the belt. A metal belt that is ion-implanted at / cm ² is more preferable.

  Further, the belt type fixing is characterized in that the metal belt is a metal belt that has been subjected to a release agent treatment comprising three steps of applying a release agent, heat treatment at 200 to 270 ° C., and applying a release agent after heating. An apparatus is more preferred.

  In addition, the image forming body of the present invention forms a toner image on the resin surface of the recording medium, and allows it to pass between the heating roller and the pressure roller while being in close contact with the metal belt surface of the belt-type fixing device. The toner image on the surface of the recording medium is thermocompression bonded so that the toner image is embedded in the thermoplastic resin layer and further moved to the position of the cooling roller while being held in close contact with the metal belt. The toner image is separated from the metal belt by cooling the toner image and the surface of the recording medium.

  The present invention provides the above-described belt type fixing device, an image forming method and an image forming body thereof, exhibiting glossiness equivalent to that of a silver salt photograph, uniform surface gloss regardless of toner density, and A toner image having a color reproducibility equivalent to that of a silver salt photograph can be obtained. Further, the belt-type fixing device of the present invention has a mirror surface with increased hardness of the belt, and by using this, there is no occurrence of toner image defects such as dents and streaks due to deformation of the belt, and the toner image High image quality can be maintained forever. Furthermore, since the stainless steel belt is provided with releasability, the release agent application / cleaning mechanism can be omitted.

{Configuration of belt type fixing device}
The belt-type fixing device of the present invention and a fixing method suitable for this fixing device will be described in more detail.

  FIG. 1 shows a belt-type fixing device of the present invention. 1 is a stainless steel belt having a specular gloss, and 2 is a heating roller. When the heating roller 2 is rotationally driven in the direction of the arrow, the belt 1 is rotationally driven by the frictional force with the roller. 3 is a heater fixedly supported by the apparatus and built in the heating roller. For example, a halogen lamp, a cartridge heater, a sheathed heater, an induction heater, or the like can be used. The heating roller 2 is made of a metal material such as stainless steel or aluminum. Reference numeral 4 denotes a cooling roller, which uses a system that circulates a water flow having a water temperature of around 15 ° C. from the outside. The belt 1 heated to 120 to 200 ° C. by the heating roller 2 comes into contact with the cooling roller 4 and is cooled to 20 to 30 ° C. The cooling roller 4 is made of, for example, a metal material such as stainless steel or aluminum. The pressure roller 5 has a rubber elastic layer having good releasability such as silicone rubber, and is pressed against the lower surface of the heating roll 2 via the belt 1 with a total pressure of 60 to 120 kg, and interlocks with the heating roll. And rotate. Reference numeral 6 denotes a toner image in which a toner image is formed on a recording medium 13 in which a thermoplastic resin is provided on a base material.

  As shown in FIG. 1, the toner image 6 is passed between the heating roller 2 and the pressure roller 5 while the toner image 6 is held in close contact with the belt surface 1, and the toner image on the surface of the recording medium 13 is thermocompression bonded. The toner image is embedded and flattened in a thermoplastic resin layer having fluidity by heating. Further, the mirror image of the belt 1 is transferred and molded on the surface of the melted toner image and the thermoplastic resin. After thermocompression bonding, after the toner image 6 is released from the pressure from the pressure roller 5, the toner image and the thermoplastic resin are melted and held in close contact with one belt surface. The toner image 6 held in close contact with the belt surface moves to the position of the cooling roller 4 and is cooled via the belt 1. At this time, the melted toner image and the surface of the thermoplastic resin are separated from the belt surface by the self-aggregating force and cured, but the toner image transferred on the mirror surface of the belt surface has high gloss. If the cooling to the toner image 6 is insufficient, the toner binder resin or the thermoplastic resin remains on the belt surface, and the glossiness of the surface of the toner image is lost.

  The cooling capacity of the toner image 6 is affected by the belt rotation speed. However, when the belt rotation speed is high, the toner image and the thermoplastic resin surface remain stuck to the belt before being sufficiently cured by cooling with the cooling roller. Pass the cooling roller. When this is forcibly removed, the toner binder resin and thermoplastic resin remain on the belt as described above. In order to perform cooling without being affected by the belt rotation speed, a cooling member 8 is provided between the heating roller and the cooling roller so as to be in contact with the inner surface of the belt. As the cooling member 8, a cooling water tank, a cooling roll, a cooling fan or the like in which a water flow having a water temperature around 15 ° C. is circulated from the outside is installed, and the belt temperature is cooled to 100 ° C. or less before the belt moves to the cooling roller To do.

{Configuration of recording medium}
A recording medium suitable for the above-mentioned fixing device is boehmite having a shape anisotropy, an aspect ratio of 1 or more, and a BET specific surface area of 100 to 180 m ² / g, and γ-alumina produced by a vapor phase method. The aqueous dispersion containing the main component is coated with 1-30 g / m ² of alumina hydrate as a solid content and dried, and then an aqueous emulsion containing a thermoplastic resin as a component is applied with 1-30 g / m ² as a resin solid content. The recording medium is obtained by casting, that is, pressing the surface of the thermoplastic resin on a heated metal mirror surface roll, drying and melting the resin, and then solidifying and peeling. The coating layer provided on the paper substrate has the effect of preventing unevenness due to toner and paper substrate fibers from being exposed due to changes over time in which the glossiness after heat-fixing decreases and humidity.

In FIG. 2A, reference numeral 9 denotes a recording medium substrate. For example, paper can be used, but it is preferable to use cardboard having a basis weight of 100 to 200 g / m ² to give a photographic texture. The planarization layer 10 is a coating layer mainly composed of boehmite and γ-alumina produced by a vapor phase method. 11 is a thermoplastic resin layer provided on the base material, and is not particularly limited as long as Tg is 35 ° C. or more lower than the toner binder resin, but an acrylic resin having a Tg of 40 to 100 ° C. is mixed. It is preferable to use in the form. If the thickness of the thermoplastic resin layer is not larger than the average particle diameter of the toner, the toner is not completely embedded in the thermoplastic resin layer. Preferably, the film thickness of the thermoplastic resin is at least twice the average particle size of the toner.

  FIG. 2B is the toner image 6 of FIG. 1 in which the toner image 12 is formed on the glossy electrophotographic paper of FIG. The electrophotographic apparatus for forming a toner image is not particularly limited, and a pulverized toner and a suspension polymerization toner or an emulsion polymerization toner obtained by suspension polymerization of a polymerizable monomer in an aqueous medium are used. Any electrophotographic apparatus may be used. FIG. 2B shows a state in which the toner is heated and fixed on the surface of the thermoplastic resin by the electrophotographic apparatus, and the toner forms irregularities on the thermoplastic resin. The unevenness of the toner depends on the thermoplastic resin on the electrophotographic apparatus or the toner / recording medium, but has a step of 4 to 8 μm for each color. Further, the level difference between the portion expressing each color and expressing the rich color and the surface of the thermoplastic resin reaches 30 μm. Therefore, the toner image until heated and fixed by a normal electrophotographic apparatus is poor in glossiness and image clarity. Further, the difference in glossiness is caused by the level of toner density, and the image has uneven glossiness. Further, since the unevenness of the toner causes scattering of reflected light, the color reproducibility of the toner pigment cannot be fully utilized. In other words, the color of the toner image having irregularities that is visually seen is a mixture of the color material such as pigment and the light from the light source in the environment, so it usually appears as a cloudy color with reduced saturation. . For this reason, the color reproducibility of an uneven toner image tends to be low.

  FIG. 2-c shows a state after the toner image of FIG. 2-b is thermocompression bonded using the belt-type fixing device of the present invention. When this fixing device is used, the toner image 12 is not simply embedded in the thermoplastic resin layer, but the mirror surface of the belt is transferred and molded on the surface of the toner and the thermoplastic resin. This toner image has a high glossiness regardless of the toner density. Further, since there is no scattering of reflected light, the original coloring ability of the toner pigment is drawn and high color reproducibility is exhibited.

{Belt material and shape}
The fixing device of the present invention is a stainless endless belt mechanism stretched by a heating roller and a cooling roller having a diameter of 50 mm to 150 mm as a condition for reduction in size and weight that can be introduced into an accessory of an electrophotographic apparatus or a digital minilab. The belt is stretched between the rollers in the above range, and the belt surrounds the rollers without a gap between each roller, and the thickness necessary for the belt to rotate stably is in the range of 0.05 mm to 0.30 mm. It is desirable to be. If the belt thickness is less than 0.05 mm, protrusions are likely to be formed on the outer peripheral side of the belt when hard foreign matter adheres to the roller. Further, when the belt thickness exceeds 0.30 mm, a gap is generated between the belt and the roller, which may deteriorate the heat transfer between the roller and the belt. The belt diameter is preferably in the range of 150 mm to 310 mm. When the belt diameter exceeds 310 mm, the distance from the thermocompression bonding portion to the cooling portion exceeds 300 mm. In this case, the end portion of the toner image held in close contact with the belt starts to be peeled off from the belt before being cooled by the cooling roller, and a glossy area is generated at the end portion of the toner image. Therefore, in order to avoid such peeling of the toner image from the belt, there are restrictions on the rotational speed and releasability of the belt.

{Belt surface roughness}
In the fixing method of the present invention, the belt mirror surface is transferred and molded on the surface of the toner image and the thermoplastic resin by thermocompression bonding. Therefore, a belt having a specular gloss is used as the belt used in the fixing device. As a belt capable of obtaining specular gloss, a stainless steel belt having a ten-point average roughness Rz of 0.2 μm or less and a centerline average roughness Ra of 0.035 μm or less is desirable. Usually, a thin stainless steel plate has a streak-like roughness in the longitudinal direction during rolling, but sufficient mirror gloss can be obtained by polishing. As a method of smoothing the surface of the belt in a mirror surface, processing methods such as roll rolling, buffing, and lapping can be used. By using the belt thus polished to form a mirror surface, it is possible to obtain 50-60% of the toner image with a glossiness equivalent to that of a silver salt photograph, that is, a glossiness of 20 °.

{Belt hardness}
Since the belt used in the fixing device of the present invention has a specular gloss, if deformation such as scratches or irregularities occurs, scratches or irregularities are transferred during thermocompression bonding of the toner image, resulting in defective portions that are particularly noticeable in photographic images. become. Such deterioration of image quality due to scratches and unevenness impairs the commercial value of digital photo prints, so it is necessary to give the belt sufficient hardness so as not to cause scratches or unevenness of the belt. The polished stainless steel belt is SUS304H with Vickers hardness Hv390. As a method for increasing the hardness without losing the mirror gloss of the stainless steel belt, an ion implantation method is preferable. In other words, nitrogen ions, fluorine ions, or carbon ions are ion-implanted into the outer peripheral portion of the stainless steel belt from the surface to a depth of 1000 mm at an implantation amount of 10 ¹⁰ to 10 ²⁰ ions / cm ² . The ion implanter is an omnidirectional ion implanter owned by Ion Engineering Laboratory Co., Ltd., which uses plasma-based ion implantation. In this injection method, a nitrogen-based or fluorine-based gas plasma is generated in a vacuum of 0.1 to 1 Pa, a stainless steel belt is exposed therein, and a high-pressure negative pulse of 10 to 30 keV and 1000 to 2000 pps is applied, Fluorine, nitrogen ions, or carbon ions are injected into the stainless steel belt surface. Here, the high-pressure negative pulse is a negative charge pulse, and an electric field corresponding to the shape of the stainless steel belt, which is a cylindrical three-dimensional object, is generated. The ions collide almost at right angles to the belt surface and are uniformly injected over the entire surface of the stainless steel belt. Nitride, fluoride, or carbide is formed on the belt surface after the injection to increase the hardness. By this ion implantation method, the Vickers hardness Hv390 of the polished stainless steel belt can be increased to Hv430 or more. This hardness is, for example, a hardness that is not noticeable as a scratch even if the tip of the tweezers is pressed against the mirror surface of the belt and scratched, and does not cause a problem in practical use. Table 1 shows the results of a strength test for scratching with a sapphire needle load of 0.98 N (100 gf). After the ion implantation, the scratch scratch depth becomes shallower corresponding to the increase in Vickers strength, and the scratch is not noticeable. In addition, scratches having a depth of 0.5 μm or less are difficult to be visually recognized as streak-like defects in the toner image after thermocompression bonding.

{Belt releasability}
The toner image and the surface of the thermoplastic resin melted in the thermocompression bonding are rapidly cooled by a cooling roller, and the resin self-aggregates and separates and cures from the belt surface. At this time, the belt surface needs to have sufficient releasability, and if the releasability of the belt surface is insufficient, the toner image cannot be firmly adhered to the belt surface and separated. In order to avoid such sticking of the toner image to the belt, a release agent treatment is performed on the belt. A desirable method for the release agent treatment is to apply a release agent treatment in which a fluorine-based release agent is applied to the outer peripheral surface of the belt by spraying or other methods and heated at a high temperature of 200 ° C. or higher. After applying the release agent, wipe the belt surface with a clean cloth and finish it to a mirror-like luster free from fogging by the release agent. Further, after allowing the belt to cool, the release agent is applied again and wiped well with a clean cloth. Thereby, permanent releasability can be imparted to the belt without impairing the specular gloss.

  When the heat treatment is not performed or when the heat is insufficient, the release agent is captured in the toner image by a single thermocompression treatment, and therefore it must be repeatedly applied for each thermocompression treatment. In addition, if heat treatment is performed at 270 ° C. or higher, the nitrogen ion or fluorine ion implanted into the belt surface by the above-described ion implantation may move to the inside of the stainless steel surface by thermal diffusion, and the belt surface hardness may become brittle. . Furthermore, if the release agent is applied excessively, the gloss of the toner image after the fixing process deteriorates, so that it is necessary to adjust the release agent application amount, and a release agent application mechanism and a cleaning mechanism are newly required. . In order to avoid such complication of the fixing device, it is more desirable to perform the above-described release agent treatment on the belt in advance.

  As described above in detail, according to the belt-type fixing device and fixing method of the present invention, the glossiness is the same as that of a silver salt photograph, the surface gloss is uniform regardless of the toner density, and the silver salt photograph A toner image having equivalent color reproducibility can be obtained. In addition, the belt-type fixing device of the present invention has an increased belt hardness. By using this belt-type fixing device, there is no occurrence of toner image defects such as dents and streaks due to deformation of the belt, and the high image quality of the toner image is permanently maintained. Can be maintained. Further, since the permanent release property is given to the stainless steel belt, the release agent application / cleaning mechanism can be omitted.

・ Measurement of properties of stainless steel belt:
The Vickers hardness Hv can be measured using a micro Vickers hardness meter manufactured by Matsuzawa according to the “Vickers hardness test method” defined in JIS Z2244.

  The ten-point average roughness Rz can be measured by a method specified in JIS B0601 using a surface roughness meter “Surf Coder SE3500” manufactured by Kosaka Laboratory Ltd.

  In the strength test against scratching, a JIS K6718 standard product was attached to HEIDON Type 14Dr with a sapphire needle, a scratch was made on the stainless steel surface at a load of 100 gf and a speed of 10 mm / min, and the width and depth of the scratch were measured with a TENCOR P-10 SURFACE PROFILER. It was long.

・ Image evaluation:
As the 20 degree glossiness (incident angle 20 ° / reflection angle 20 °), “Gloss meter VG-2000” manufactured by Nippon Denshoku Industries Co., Ltd. was used.

  In the evaluation pattern of CMYK images, gloss unevenness was created by measuring areas of 20, 40, 60, and 100 percent for the four colors of cyan, magenta, yellow, and black, and these were output by an electrophotographic apparatus. After the toner image was thermocompression bonded, the glossiness of 20 degrees was measured for each percent measurement area using “Glossmeter VG-2000” manufactured by Nippon Denshoku Industries Co., Ltd.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

<Example 1>
As an embodiment of the present invention, the configuration of a belt-type fixing device will be described with reference to FIG. The heating roller 2, the pressure roller 5 and the cooling roller 4 are designed and manufactured with a diameter of 100 mm. Reference numeral 8 denotes a cooling water tank whose bottom (50 mm × 300 mm) is in contact with the belt surface.

  The belt 1 is a cylinder having a diameter of 280 mm, a width of 300 mm, and a thickness of 0.15 mm. The outer peripheral surface is polished, the ten-point average roughness Rz of the surface roughness is 0.2 μm, and the center line average roughness Ra is 0.1. A stainless steel belt of 030 μm is used.

Further, fluorine ions were implanted into the outer peripheral surface of the stainless steel belt using a plasma-based ion implantation method. As the fluorine gas, CF ₄ gas was used, and the ion implantation conditions were a pressure of 0.5 Pa during ion implantation, a high-pressure negative pulse of −12 keV applied to a stainless steel belt, a pulse frequency of 1000 pps, a pulse width of 10 μs, and a treatment time of 60 minutes. The Vickers hardness after ion implantation was Rz440.

  Subsequently, a release agent treatment for the stainless steel belt was performed. The mold release agent used was a fluorine-based mold release agent mold spat MR-K644 manufactured by Seimi Chemical Co., Ltd., and this was applied to the surface of the stainless steel belt. When the belt surface clouded with a release agent was thoroughly wiped with a cloth and finished to a mirror surface, it was placed in an oven and subjected to a heat treatment at 220 ° C. for 30 minutes. After the belt is heated, it is allowed to cool and the release agent is applied again. Then, the belt surface clouded with a release agent is thoroughly wiped with a cloth and finished to a mirror surface.

The recording medium was a paper having a basis weight of 175 g / m ² , coated with an aqueous dispersion of boehmite (Dispersal HP15, manufactured by SASOL), dried at a solid content of 20 g / m ² , and then acrylic manufactured by Nissin Chemical Industry Co., Ltd. A resin emulsion was used to apply a mixed coating solution having a Tg of 85 ° C. and 40 ° C. at a solid content of 20 g / m ² and dried by casting. As an electrophotographic apparatus for forming a toner image on the recording medium, a color copying machine iRC3200N manufactured by Canon Inc. using suspension polymerization toner was used to form a toner image.

  The belt-type fixing device was set to the thermocompression bonding conditions shown in Table 2 in a state where the belt 1 was driven to rotate, the heater 3 was energized, and the cooling roller 4 and the cooling water tank 8 were circulating water.

  The recording medium on which the toner image has been formed is conveyed along the paper feed unit 7 to the heating / pressure roller side, and the recording medium is in close contact with the stainless steel belt from its leading end and inserted between the heating / pressure roller. Here, the toner image is thermocompression bonded under the conditions shown in Table 2, and the toner image and the thermoplastic resin on the surface of the recording medium are melted. At this time, the toner image is embedded in the thermoplastic resin, and at the same time, a mirror surface is transferred and molded on the surface of the toner image and the thermoplastic resin. Further, the recording medium is brought into close contact with the belt surface and moves to the cooling roller position. In the cooling unit, the toner image and the thermoplastic resin are cooled to 40 ° C. or lower and cured, and the recording medium on which the toner image having high gloss is formed is separated from the belt surface. On the belt surface from which the recording medium is separated, no resin residue remains and the mirror gloss is maintained. Subsequently, the thermocompression treatment was repeated, and no release defects occurred with the number of processed sheets of 1000, so it was confirmed that the release property of the stainless steel belt was maintained.

  In addition, when the glossiness of the toner image was evaluated under the heat fixing conditions 1 to 3 in Table 2, the glossiness was 66% to 72% at 20 ° glossiness regardless of the density of the toner density. Obtained. FIG. 4 is a graph showing the uniformity of the 20 ° glossiness with respect to the toner density.

<Example 2>
The configuration of the belt-type fixing device and the stainless steel belt are the same as those in the first embodiment. However, a cooling roll in which 15 ° C. cooling water was circulated was adopted as the cooling member. The recording medium is the same as in the first embodiment. In Example 2, as an electrophotographic apparatus for forming a toner image on the recording medium, a color copier CLC1100 manufactured by Canon Inc. using pulverized toner was used to form a toner image. Table 3 shows the thermocompression bonding conditions for this toner image.

  Although repeated evaluation of the thermocompression bonding treatment was performed in the same manner as in Example 1, no release defects occurred with a throughput of 1000 sheets. When the glossiness of the toner image was evaluated under the thermal fixing conditions 4 to 6 in Table 3, the glossiness showed a high value regardless of the density of the toner density, and the glossiness at 20 ° was 73 to 82%. FIG. 5 is a graph showing the uniformity of the glossiness at 20 degrees with respect to the toner density.

<Example 3>
The configuration of the belt-type fixing device is the same as that of the first embodiment. After polishing the outer peripheral surface of the stainless steel belt, nitrogen ions were implanted into the outer peripheral surface of the stainless steel belt using a plasma-based ion implantation method. Nitrogen gas is N ₂ gas, the pressure during ion implantation is 0.5 Pa, the high-pressure negative pulse applied to the stainless steel belt is −12 keV, the pulse frequency is 1000 pps, the pulse width is 10 μs, and the treatment time is 60 minutes. . Subsequently, a release agent treatment for the stainless steel belt was performed. The mold release agent used was Daikin Industries, Ltd., a fluorine-based mold release agent, Die Free GA-3011, which was applied to the surface of the stainless steel belt. The belt surface clouded with the release agent was thoroughly wiped with a cloth and finished to a mirror surface, and then placed in an oven and subjected to a heat treatment at 250 ° C. for 30 minutes. After the heat treatment, the release agent was applied again to the belt, and it was wiped with a cloth and finished to a mirror surface. The production of the recording medium, the electrophotographic apparatus for forming the toner image, and the thermal fixing conditions are the same as those in the second embodiment.

  As a result of the repeated evaluation of the thermocompression treatment, the same result as in Example 1 was obtained. The same high glossiness as in Example 2 was obtained.

<Comparative Example 1>
The configuration of the belt-type fixing device, the recording medium, and the toner image forming method are the same as those in the second embodiment. The belt used was a resin belt in which a polyimide film having a thickness of 70 μm was coated with a fluorine resin as a surface layer to a thickness of 10 μm. The thermocompression treatment was repeatedly evaluated under the thermocompression bonding conditions shown in Table 3. The belt separates the toner image from the belt without applying a release agent. However, after the thermocompression bonding, the 20 ° glossiness of the toner image is about 40%, and it was reduced to 22% when 1000 sheets of the thermocompression treatment were repeatedly evaluated. The decrease in the glossiness is due to an increase in the unevenness of the belt surface as the thermocompression treatment is repeated.

<Comparative example 2>
The configuration of the belt-type fixing device, the recording medium, and the toner image forming method are the same as those in the second embodiment. The belt had a polished outer peripheral surface, and a stainless steel belt having a 10-point average roughness Rz of the surface roughness of 0.2 μm and a center line average roughness Ra of 0.030 μm was used as it was. When thermocompression bonding was attempted under the thermocompression bonding conditions shown in Table 3, sticking occurred on the belt surface. In addition, many fine scratches were generated on the belt surface by wiping the cloth after removing the sticking.

<Comparative Example 3>
The configuration of the belt-type fixing device, the recording medium, and the toner image forming method are the same as those in the second embodiment. As in Example 2, the belt used was subjected to polishing and ion implantation. A release agent treatment was performed at 140 ° C., the release agent was applied again, and wiped with a cloth until a mirror gloss was obtained. Although repeated evaluation was performed under the thermocompression bonding conditions shown in Table 3, sticking occurred in 10 to 15 sheets.

  Further, when the release agent was repeatedly applied for each thermocompression treatment, the glossiness of the toner image was varied for each thermocompression treatment, and the glossiness was unstable at 42 to 60% at 20 ° glossiness.

<Comparative example 4>
The configuration of the belt-type fixing device and the toner image forming method are the same as those in the second embodiment. As in Example 2, the belt used was subjected to polishing and ion implantation. A release agent treatment was performed at 140 ° C., the release agent was applied again, and wiped with a cloth until a mirror gloss was obtained. The recording medium was prepared by coating a 175 g / m ² paper with an acrylic resin emulsion manufactured by Nissin Chemical Industry Co., Ltd., and applying a mixed coating solution of Tg 85 ° C. and 40 ° C. at a solid content of 20 g / m ² . When thermocompression bonding was attempted under the thermocompression bonding conditions shown in Table 3, the glossiness at 20 degrees was 55% immediately after thermocompression bonding, but it decreased to 40% after 2 weeks.

It is a figure which shows the mechanism (cooling member: cooling water tank) of a belt-type fixing device. It is a figure which shows the mode of embedding of the toner in a thermoplastic resin layer. It is a figure of another form (cooling member: cooling roll) which shows the mechanism of a belt-type fixing device. It is a graph which shows the uniformity of 20 degree | times glossiness with respect to a toner density of the image using a suspension polymerization toner. It is a graph which shows the uniformity of 20 degree glossiness with respect to the toner density of the image using the pulverized toner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stainless steel belt 2 Heating roller 3 Heater 4 Cooling roller 5 Pressure roller 6 Toner image 7 Paper feed part 8 Cooling member 9 Recording medium base material 10 Planarizing layer 11 Thermoplastic resin layer 12 Toner image 13 Recording medium

Claims (12)

  A heating / pressurizing mechanism in which a metal endless belt is stretched and driven and rotated by two axes of a heating roller and a cooling roller, and a pressure roller presses from the outer peripheral side of the metal belt surrounding the heating roller, and cooling A belt-type fixing device comprising a cooling mechanism provided with a cooling member so as to contact the inner surface of the metal belt between the heating roller and the cooling roller, and a surface of the metal belt surrounding the roller.   The belt-type fixing device according to claim 1, wherein the heating roller and the cooling roller have a diameter of 50 mm to 150 mm.   The belt-type fixing device according to claim 1, wherein the cooling member is one of a cooling water tank, a cooling roll, and a cooling fan.   The belt fixing device according to claim 1, wherein the metal belt has a thickness of 0.05 mm to 0.30 mm.   The belt-type fixing device according to claim 1, wherein the metal belt has a diameter of 150 mm to 310 mm.   The metal belt is a stainless steel belt having a mirror surface with a ten-point average roughness Rz of 0.2 μm or less and a center line average roughness Ra of 0.035 μm or less. The belt-type fixing device according to any one of the above.   7. The belt type fixing device according to claim 1, wherein the metal belt is a stainless steel belt having a Vickers hardness Hv of 430 to 500. In the metal belt, any one of nitrogen ions, fluorine ions, and carbon ions is implanted in an amount of 10 ¹⁰ to 10 ²⁰ ions / cm ² from the surface to a depth of 1000 mm with respect to the entire surface on the outer peripheral side of the belt. The belt-type fixing device according to claim 1, wherein ion implantation is performed.   9. The metal belt according to claim 1, wherein the metal belt is a metal belt subjected to a release agent treatment comprising three steps of applying a release agent, heat treatment at 200 to 270 [deg.] C., and applying a release agent after heating. The belt-type fixing device according to any one of the above.   A toner image is formed on a resin surface of a recording medium having a thermoplastic resin layer on a substrate, and the recording medium on which the toner image is formed is in close contact with the metal belt surface of the belt-type fixing device according to claim 1. The recording medium includes a step of embedding the toner image in a thermoplastic resin layer by thermocompression bonding the toner image on the surface of the recording medium while passing between the heating roller and the pressure roller. The recording medium on which the toner image on the surface is thermocompression-bonded is moved to the cooling roller position while being held in close contact with the metal belt, and the toner image and the surface of the recording medium are rapidly cooled by the cooling roller via the metal belt. And a step of separating the recording medium on which the flat toner image is formed from the metal belt. The recording medium is an aqueous dispersion mainly composed of boehmite having a shape anisotropy and an aspect ratio of 1 or more and a BET specific surface area of 100 to 180 m ² / g and γ-alumina produced by a vapor phase method on a paper base material. After the body is coated with ¹ to 30 g / m ² as a solid content of boehmite and γ-alumina and dried, an aqueous emulsion containing a thermoplastic resin as a solid content is applied with 1 to 30 g / m ² and heated. The toner image forming method according to claim 10, wherein the toner image forming method is a recording medium obtained by pressure-bonding a thermoplastic resin surface to a metal mirror surface, drying, melting the resin, and solidifying and separating the recording medium.   An image forming body comprising an image formed by the toner image forming method according to claim 10.

Images