JP2009300502A - Ceramic roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic roller which is equipped with a shaft core formed of metal and a cylindrical layer formed of ceramic and formed on the outer periphery side of the shaft core, which does not cause a local density variation on the cylindrical layer and has low heat conductivity. <P>SOLUTION: The ceramic roller 10 used in the thermal fixing device of an electrophotographic device that uses a charged image comprises the shaft core 4 formed of metal and the cylindrical layer 1 formed of ceramic and formed on the outer periphery side of the shaft core 4. A gap 12 is formed between the shaft core 4 and the cylindrical layer 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ceramic roller having a shaft core and a cylindrical body layer formed on the outer peripheral side of the shaft core, and more particularly to a heat fixing device mounted on an electrophotographic apparatus such as an electrophotographic copying machine or a printer using a charged image. The present invention relates to a ceramic roller used.

  An electrophotographic apparatus such as an electrostatic copying machine or a laser printer projects an optical image onto a uniformly charged photoreceptor surface in the dark, and an electrostatic latent image corresponding to the optical image is formed on the photoreceptor surface. The image is developed by spraying charged toner, which is a developer, on the surface of the photoconductor and electrostatically adhering it, and the surface of the printing paper charged to the opposite polarity to the charge of the toner is superimposed on the surface of the photoreceptor. The image is copied by transferring it onto a paper surface and heating and melting the toner on the paper surface under pressure by a heat fixing roller and then heat-fixing the toner on the paper surface.

  As the heat fixing device portion for fixing the toner on the paper surface with the heat fixing roller, the heat fixing roller is usually composed of two rollers, a heat fixing roller and a pressure roller, or a heat fixing roller, a pressure roller and a conveying roller. And a roller having an endless belt wound between one of a heat fixing roller or a pressure roller and a conveying roller. That is, the printing paper is supported from the back side by a pressure roller or a pressure roller via an endless belt, and is pressed and heated by a heat fixing roller heated from the front side, so that the toner on the paper surface is fused. Heat fixing. The temperature of the heat fixing roller is generally about 150 to 200 ° C. However, when the temperature of the roller is increased, it may be temporarily reached due to overshoot.

  In order to fuse the toner on the paper surface by the heat fixing roller, it is heated to a high temperature capable of fusing, but when the heat fixing operation is performed, the printing paper or pressure roller, which is always much lower than the heat fixing temperature, Or since it contacts and rotates with the endless belt, a large amount of heat energy is taken away and cooled at that moment. For this reason, the heat fixing roller needs to be heated to a higher temperature in anticipation of cooling due to such contact, and power consumption increases. Therefore, the pressure roller is required to have a low thermal conductivity, that is, heat insulation. Further, since the pressure roller is in contact with the high-temperature heat fixing roller, heat resistance is also required. As such a pressure roller, a pressure ceramic roller comprising a shaft core and a porous ceramic cylindrical layer formed on the outer periphery of the shaft core has been proposed (Japanese Patent Laid-Open No. 2004-86219).

  In such a pressure ceramic roller, cylindrical porous ceramics are attached to the shaft core by press-fitting or using an adhesive, and the shaft core and the cylindrical porous ceramics are in close contact or bonded via an adhesive layer. Has been.

However, the method of press-fitting cylindrical porous ceramics into the shaft core is (1) high thermal conductivity, (2) local variation in density due to insertion friction that occurs during assembly to the shaft core. As a result, there is a problem that a part where heat easily escapes and is not easily heated (high density) occurs, and (3) productivity is lowered due to frictional resistance generated when the shaft is assembled. In addition, the method of fixing the cylindrical porous ceramic and the shaft core with an adhesive (4) increases the thermal conductivity, (5) it is necessary to prepare and store a separate member called an adhesive, (6 ) The adhesive coating process and the drying process are required, and there is a problem that the manufacturing process becomes complicated.
JP 2004-86219 A JP 2007-272051 A

  Accordingly, an object of the present invention is to provide a ceramic roller having a shaft core and a ceramic cylindrical layer formed on the outer periphery of the shaft core without causing local density variations in the cylindrical layer. An object of the present invention is to provide a ceramic roller having a low thermal conductivity.

  Under such circumstances, the present inventors have conducted intensive studies, and as a result, a ceramic roller used in a heat fixing device of an electrophotographic apparatus using a charged image, which is formed on an axis and an outer peripheral side of the axis. If the gap is formed between the shaft core and the cylindrical body layer, there is no local density variation in the cylindrical body layer, and the ceramic has low thermal conductivity. The present inventors have found that a roller can be obtained and completed the present invention.

  That is, the present invention is a ceramic roller used in a thermal fixing device of an electrophotographic apparatus using a charged image, comprising a shaft core and a ceramic cylindrical layer formed on the outer peripheral side of the shaft core, A ceramic roller having a gap formed between the shaft core and the cylindrical body layer is provided.

  According to the ceramic roller of the present invention, when the cylindrical body layer is inserted into the shaft core, since the inner diameter of the cylindrical body layer is slightly larger than the outer diameter of the shaft core, insertion friction hardly occurs. There is no local density variation in the body layer. Moreover, since air exists between the shaft core and the cylindrical body layer, the thermal conductivity can be lowered.

  The ceramic roller of the present invention includes an axial core, a gap, and a ceramic cylindrical layer in order from the center to the outside. In the present invention, ceramic refers to a material mainly composed of a nonmetallic inorganic material. In the present invention, the shaft core is not particularly limited as long as it is a metal or a hard resin that can withstand use, and examples thereof include iron, stainless steel, aluminum, copper, brass, carbon steel, polycarbonate, and hard nylon. .

  In the present invention, the ceramic cylindrical layer formed on the outer peripheral side of the shaft core is not particularly limited, and has a high heat insulating property, a high heat resistance, and a high strength expressed by low thermal conductivity and low heat capacity. Specific examples include ceramics mainly composed of calcium silicate and heat-resistant fibers as reinforcing fibers, and ceramics mainly composed of inorganic binder and heat-resistant fibers. Ceramics containing the main component and heat-resistant fibers as the reinforcing fibers are preferable in terms of low thermal conductivity. The cylindrical body layer may be any of a single cylindrical body, a laminate in which block-shaped cylindrical bodies are laminated in the longitudinal direction of the axial core, and a laminate in which ring-shaped sheet pieces are laminated in the longitudinal direction of the axial core. Good.

  In ceramics containing calcium silicate as the main component and heat-resistant fiber as the reinforcing fiber, the calcium silicate is preferably a compound formed by hydrothermal reaction of a siliceous raw material and a calcium raw material in the presence of water. . Examples of calcium silicate crystals include, for example, zonotlite crystals, tobermorite crystals, amorphous C—S—H crystals, etc. In particular, compacts made of zonotolite crystals are lightweight and have a very high specific strength, heat resistance and heat insulation. It is preferable because of its superiority. The zonotlite crystal is the same as that described in JP-A-2007-272051, and aggregates and bonds to form secondary particles, but in the cylindrical layer in the present invention, it exists as a flat shape. Yes.

  Heat resistant fibers used in combination with calcium silicate are used as reinforcing fibers, and include heat resistant inorganic fibers and heat resistant organic fibers. Examples of the heat-resistant inorganic fiber include alumina silica fiber, alumina fiber, Christo tile, carbon fiber, glass fiber, slag wool, silica fiber, zirconia fiber, gypsum whisker, silicon carbide fiber, potassium titanate whisker, and aluminum borate whisker. , High silicate fiber, fused silica fiber, rock wool, wollastonite, and the like. Examples of the heat-resistant organic fiber include aramid fiber. In addition, these heat resistant fibers can be used individually by 1 type or in combination of 2 or more types.

  In addition to calcium silicate and heat-resistant fibers, the cylindrical body layer may contain reinforcing materials, fillers, lightweight aggregates, and the like at any blending ratio as necessary. Examples of the reinforcing material include cement and gypsum, examples of the filler include talc, diatomaceous earth, and fly ash. Examples of the lightweight aggregate include microsilica, pearlite, shirasu balloon, and glass balloon. The blending amount is, for example, 5 to 95 parts by mass, preferably 20 to 60 parts by mass, and 0 to 36 parts by mass of the reinforcing material, preferably 100 parts by mass of secondary particles of zonotlite crystals. 7 to 15 parts by mass, 0 to 30 parts by mass of filler, and 0 to 30 parts by mass of lightweight aggregate.

  Examples of the ceramic mainly composed of the inorganic binder and the heat-resistant fiber include those similar to those disclosed in JP-A No. 2004-301293.

  The inorganic binder is a material that becomes a ceramic component by itself in the drying and firing processes and consolidates the heat-resistant fibers. The inorganic binder is not particularly limited, and examples thereof include glass frit, colloidal silica, alumina sol, silica sol, sodium silicate, titania sol, lithium silicate, and water glass. These inorganic binders can be used alone or in combination of two or more.

  The heat resistant fiber includes a heat resistant inorganic fiber and a heat resistant organic fiber. Examples of the heat-resistant inorganic fiber include alumina silica fiber, alumina fiber, Christo tile, carbon fiber, glass fiber, slag wool, silica fiber, zirconia fiber, gypsum whisker, silicon carbide fiber, potassium titanate whisker, and aluminum borate whisker. , High silicate fiber, fused silica fiber, rock wool, wollastonite, and the like. Examples of the heat-resistant organic fiber include aramid fiber. These heat resistant fibers can be used singly or in combination of two or more.

  In ceramics mainly composed of an inorganic binder and heat-resistant fibers, a particulate heat-resistant inorganic material can be blended in addition to the heat-resistant fibers. Particulate heat-resistant inorganic materials include clay, calcium carbonate, talc, silica, aluminum, magnesium oxide, calcium oxide, zirconia, titania, sepiolite, kaolin, zeolite, silicon nitride, aluminum nitride, aluminoborosilicate, aluminosilicate, and porous Examples include carbonaceous materials. Moreover, hollow materials, such as hollow ceramics and a glass balloon, can also be used as a particulate heat-resistant inorganic material. In addition, these particulate heat-resistant inorganic materials can be used individually by 1 type or in combination of 2 or more types.

  In the ceramic roller of the present invention, a gap (X) is formed between the shaft core and the cylindrical body layer. Thereby, when inserting the cylindrical body layer into the shaft core, almost no insertion friction is generated, and therefore there is no local density variation in the cylindrical body layer. Moreover, since air exists between the shaft core and the cylindrical body layer, the thermal conductivity can be lowered. In the ceramic roller of the present invention, an adhesive that has been conventionally used for bonding the shaft core and the cylindrical body layer is not used.

  The gap (X) is 0.05 ≦ X ≦ 3 mm, preferably 0.05 ≦ X ≦ 2 mm, more preferably 0.05 ≦ X ≦ 1 mm, and even more preferably 0.05 ≦ X ≦ 0. .1 mm. In the method in which the cylindrical body layer is pressed into the shaft core and the cylindrical body layer is fixed to the shaft core, the cylindrical body layer is damaged at the time of press-fitting, or friction powder is filled in the gap to cause insertion friction, resulting in density variation (heat Unevenness) occurs. Further, if the gap exceeds 3 mm, the frictional force between the contact surfaces of the cylindrical bodies is reduced, and there is a concern about the rotational displacement between the cylindrical bodies. Although the cylindrical body layer (heat insulating layer) can be thickened by increasing the outer diameter of the cylindrical body layer, it is not preferable because it becomes an obstacle to downsizing of the entire apparatus.

  The gap (X) is preferably completely non-contact, but is not limited thereto, and there may be a slight contact portion. The gap (X) is such that when the cylindrical body layer is inserted into the axial center, the insertion load per circumference of the inner diameter of the cylindrical body layer is 0 to 80 N / cm, preferably 0 to 58 N / cm. Including those obtained. Strictly speaking, the gap obtained with a load in the vicinity of an insertion load of 80 N / cm can be substantially defined as a gap, although there are a few places where partial contact is made. Even in such a partially contacting gap, density unevenness does not occur in the cylindrical body layer, and when inserting the cylindrical body layer into the shaft core, the insertion resistance is reduced and productivity is improved. The object of the present invention can be achieved. In the case of the conventional press-fitting method, the insertion load may be 580 N / cm, and the insertion load 80 N / cm is a very small load compared to this. When the inner diameter of the cylindrical layer is 22 mm, the insertion load is 0 to 550 N, preferably 0 to 400 N.

  The gap (X) can be determined using, for example, an inner diameter measuring device. Examples of the inner diameter measuring device include a three-point inner micrometer having a minimum display amount of 0.001 mm. That is, the gap (X) disassembles the ceramic roller, takes out the cylindrical body layer, disassembles it into unit lengths (block bodies) as necessary, compresses the block bodies again to the original length, and then Is measured by an inner diameter measuring instrument, and the difference from the outer diameter of the shaft core may be obtained by halving.

  An example of the ceramic roller of the present invention will be described with reference to FIG. 1A is a cross-sectional view of a ceramic roller, and FIG. 1B is a cross-sectional view of a cylindrical body layer before compression used in the ceramic roller of FIG. The ceramic roller 10 includes a metal shaft core 4, a gap (air layer) 12, and a ceramic cylindrical body layer 1 in this order from the center toward the outside. The shaft core 4 includes a flange 2 that can hold the cylindrical body layer 1 mounted on the shaft core 4 from both sides with a predetermined pressing force, and a journal portion 3. That is, the shaft core 4 and the cylindrical body layer 1 are fixed by the frictional resistance between the flange 2 located on both sides of the shaft core 4 and the end face of the cylindrical body layer 1. The cylindrical body layer 1 is formed by stacking approximately several hundred ring-shaped objects having the same physical properties and the same size, and is compressed in the longitudinal direction of the shaft core 4 and fixed to the shaft core 4. In the present invention, the number of laminated ring-shaped materials is 2 to 17, preferably 3.5 to 10, per 10 mm unit length after compression. Therefore, for example, when the length of the cylindrical body layer 1 is 300 mm, the number is 60 to 510, preferably 105 to 300.

In ceramic roller 10, the axis longitudinal length l ₁ after being mounted in the axial 4 is smaller than axial longitudinal length l ₀ before being mounted in the axial 4. That is, l ₁ <l ₀ and l ₀ −l ₁ = Δl is the compression length. The compression length Δl is a reduction obtained by applying pressure accompanied by a density increase of 0.02 g / cm ³ or more when the density in the axial center direction of the cylindrical body layer 1 is fixed during compression. With this compression length, the frictional resistance between the flange and the end face of the cylindrical body layer is sufficient, and a desired rotational torque can be obtained. The desired rotational torque varies depending on the specifications of the heat fixing device of the electrophotographic apparatus to be used, and may be determined as appropriate within a range where the compression pressure increases in density by 0.02 g / cm ³ or more.

In the ceramic roller of the present invention, the bulk density of the ceramic of the cylindrical body layer is usually 0.05 to 0.7 g / cm ³ , preferably 0.25 to 0.5 g / cm ³ . Further, the heat capacity of the ceramic of the cylindrical body layer is 0.04 to 0.65 J / K · cm ³ , preferably 0.04 to 0.4 J / K · cm ³ . Moreover, the thermal conductivity of the ceramic of only the compressed cylindrical body layer is 0.01 to 0.15 W / m · K, preferably 0.04 to 0.15 W / m · K, more preferably 0.8. It is 06-0.12 W / m * K. The thermal conductivity of the ceramic roller comprising the shaft core, gap and cylindrical layer of the present invention is 0.04 to 0.15 W / m · K, preferably 0.06 to 0.12 W / m · K. It is.

The heat capacity (KJ / cm ³ ) can be calculated from the value of bulk density by pulverizing a sample, measuring 50 g of the sample using a high temperature sample dropping type specific heat measuring device, and measuring the specific heat. Moreover, the thermal conductivity (W / m · K) of the ceramic of the compressed cylindrical body layer is a flat plate having a width of 100 mm, a thickness of 20 mm, and a length of 50 mm, which is the same density as that of the ceramic roller. The thermal conductivity (W / m · K) of the ceramic roller consisting of a shaft core, a gap and a cylindrical body layer is measured on the surface of the cylindrical test specimen, and the cylindrical roller layer surface of the ceramic roller conforms to JIS R2618 unsteady hot wire method. And measured at room temperature using a rapid thermal conductivity meter QTM-500 (manufactured by Kyoto Electronics Industry Co., Ltd.). In addition, said cylindrical body layer may be comprised from the ceramic layer of different bulk density and heat capacity. For example, the portion close to the outer peripheral surface may be a ceramic layer having a relatively lower heat capacity than the inside.

  In the ceramic roller of the present invention, the outer periphery of the cylindrical body layer can be further coated with an inorganic surface layer such as a fluorine resin layer such as a film of PFA resin, a silicone rubber layer, or a glass layer. Thereby, the surface can be smoothed, the slidability can be improved, and the releasability can be imparted.

  Next, the manufacturing method of the ceramic roller of this invention is demonstrated. The method for producing the ceramic roller of the present invention includes a step I for preparing a slurry or a water-based kneaded material by mixing raw materials containing heat-resistant fibers and water, a step II for obtaining a molded body from the slurry or the water-based kneaded material, a shaft And III step of forming a cylindrical body layer around the core. The shape of the molded body obtained in the step II is, for example, a sheet shape, a plate shape, a quadrangular columnar shape or a columnar shape, and these are appropriately processed into a cylindrical shape in the step III, or after the step II and before the step III. The

  As a preferable method for producing a ceramic roller of the present invention, a slurry preparing step of preparing a slurry by mixing raw materials containing heat-resistant fibers and water, and a forming step of obtaining a sheet from the slurry by a suction dehydration forming method or a papermaking method, A punching process for punching the sheet in the thickness direction to obtain a ring-shaped sheet piece; a process for passing the shaft core through the hollow portion of the ring-shaped sheet piece and compressing and fixing the molded piece in the longitudinal direction of the shaft core; The method which has this is mentioned.

  In the slurry preparation step, a slurry containing heat-resistant fibers and calcium silicate or a slurry containing heat-resistant fibers and an inorganic binder can be used. Among these, a slurry containing heat-resistant fibers and calcium silicate is preferable in terms of low thermal conductivity. Calcium silicate is obtained through a crystallization process for obtaining calcium silicate crystals. That is, the type of calcium silicate crystal obtained in the crystallization step may be any of a zonotlite crystal, a tobermorite crystal, or an amorphous C—S—H crystal, but a secondary particle of the zonotrite crystal is generated. Is preferred. A suitable crystallization process is described in Japanese Patent Application Laid-Open No. 2007-272051. Examples of the heat resistant fiber to be blended in the slurry are the same as those described in the description of the cylindrical body layer.

  In the slurry preparation step, the slurry may further contain a reinforcing material, a filler, or a lightweight aggregate as an optional component in addition to the heat-resistant fiber and the calcium silicate crystal. By adding such an optional component, a calcium silicate crystal-containing molded body having higher strength can be obtained. Examples of the heat-resistant fiber, the reinforcing material, the filler, and the lightweight aggregate are the same as those described in the description of the cylindrical body layer.

The forming step is a step of obtaining a sheet from the slurry by a dehydration forming method or a papermaking method. The forming step may also serve as a step of flattening the secondary particles of the zonotlite crystal and making the orientation of the flat zonotlite secondary particles in a certain direction. The sheet is formed into a sheet by a paper machine that scrapes raw materials such as zonotlite from the slurry. The paper machine is composed of a net for scoring the raw material, a press machine for compressing it, a dryer, and the like, and a long paper machine, a round paper machine, or the like may be used. The density of the sheet is appropriately determined in the range of, for example, 0.2 to 0.5 g / cm ³ according to the bulk density of the cylindrical body layer to be produced. Incidentally, the flattening of the secondary particles of the zonotlite crystal may be performed during the assembly compression process to the shaft core. In this case, the bulk density of the sheet is 0.02 g / cm from the final cylindrical bulk density. Lighten ³ or more. The density of the sheet may be adjusted by changing the bulk of the zonotolite crystal secondary particles in the slurry or the pressure of a press or the like performed after dehydration molding. For example, when the zonotolite crystal secondary particles are made bulky, a sheet having a relatively low bulk density can be obtained. The bulk density of the zonotlite crystal secondary particles is adjusted by appropriately changing the starting material, the concentration of the slurry, the stirring conditions, and the like. The thickness of the sheet (symbol t in FIG. 2) can be adjusted from 0.6 to 6 mm. However, when the thickness is adjusted to 1.2 to 3.4 mm, the influence of density variation generated in the sheet thickness direction is further reduced. This is preferable. The molding pressure is usually 1-100 kgf / cm ² , preferably 1-10 kgf / cm ² . In the case of the papermaking method, the orientation direction of the flat zonotlite secondary particles and the heat-resistant fiber is perpendicular to the direction in which water drops by gravity from the papermaking machine. The sheet obtained by the above method can be dried by a known technique. The drying conditions are usually 50 to 300 ° C for 0.1 to 24 hours, preferably 150 to 250 ° C for 0.1 to 10 hours.

An example of a punching process for punching the molded body in the thickness direction to obtain a ring-shaped sheet piece will be described with reference to FIG. FIG. 2 is a diagram for explaining an example of a process for obtaining a ring-shaped sheet piece from a sheet obtained by the papermaking method. In FIG. 2, a sheet molded body 6 having a thickness t is punched out using, for example, a double cylindrical blade (not shown) to obtain a ring-shaped sheet piece 11 having an outer diameter d ₂ and an inner diameter d ₁ . A punching machine using a plurality of double cylindrical blades having the same shape is preferably used to obtain a large number of ring-shaped objects by a single punching because the productivity can be improved. The number of ring-shaped sheet pieces 11 stacked is 2 to 17, preferably 3.5 to 10, per 10 mm unit length after compression.

  In addition, what is obtained from the sheet | seat obtained by the dehydration molding method or the papermaking method is not limited to said ring shape, The square-shaped thing which has a round hole may be sufficient. In this case, after assembling to the shaft core, the rectangular columnar object is processed into a cylindrical object.

Next, incorporate a ring-shaped sheet piece 11 in the axis 4 of the shaft diameter d _3. As an assembling method, a ring-shaped sheet piece 11 is inserted into the shaft core 4 one by one and incorporated one after another, a ring-shaped sheet piece 11 stacked on the shaft core 4 is inserted and assembled, For example, a method of inserting the shaft core 4 into the ring-shaped sheet piece 11 formed can be used. When installing the ring-shaped sheet piece 11 in the shaft 4, since the inner diameter d ₁ of the annular sheet piece 11 is slightly larger than the shaft diameter d ₃ of the shaft 4, or not inserted friction hardly occurs, generating Even if it does not affect the insertion work. How much the difference between the inner diameter d _{1 of the} ring-shaped sheet piece 11 and the shaft diameter d ₃ of the shaft core 4 is determined is the target value of the material, thickness, number of sheets used, and gap (X) of the ring-shaped sheet piece 11. It may be determined as appropriate in consideration of the above.

  As a method of compressing and fixing the ring-shaped sheet piece 11 in the longitudinal direction of the shaft core so as to have a predetermined compression length Δl (see FIG. 3), for example, a method of screwing a flange with a female screw or a press-fitting And a method of fixing the formed piece and the unevenness formed on the shaft core by knurling. Thereby, the ceramic roller 10 can generate rotational torque by the compressive force between the flanges 2. Therefore, the adhesive between the shaft core 4 and the cylindrical body layer 1 may not be used. Moreover, since the flexible paper is compressed in the longitudinal direction of the cylindrical body layer 1, no gap is generated between the papers, and no gap is generated on the surface of the cylindrical body layer. In this compression and fixing step, the thickness of the ring-shaped sheet piece 11 constituting the cylindrical body layer is approximately 0.5 to 5 mm before compression, and is approximately 1.2 to 3.4 mm before compression. Is approximately 1 to 3 mm. In FIG. 3, for simplicity of drawing, the shaft core 4 is shown broken, but is actually continuous.

  In the production method described above, the firing step (autoclave) is an optional step. However, when performing the firing step, it is preferable to obtain the sheet-like sheet piece 11 after firing in that a dimensional change does not occur. After the molded piece is mounted on the shaft core, a surface layer such as a fluororesin layer such as a film of PFA resin, a silicone rubber layer, or a glass layer can be further coated on the outer periphery of the cylindrical body layer by a known method.

  Since the ceramic roller of the present invention has a gap between the shaft core and the cylindrical body layer, there is no density unevenness due to insertion friction, and the thermal conductivity is uniform and small, so that the heat insulation is excellent. For this reason, it can be used for a ceramic roller requiring heat insulation used in a heat fixing device mounted on an electrophotographic apparatus such as an electrophotographic copying machine or a printer. That is, the use of the ceramic roller of the present invention is called by various names, for example, a pressure roller, a conveyance roller, an auxiliary roller, a drive roller, a peeling roller, a tension roller, a drive roller, a guide roller, etc. Is mentioned.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

(Formation of zonotlite crystals)
As a calcareous material, quick lime was poured into 24 times the amount of 90 ° C. hot water and digested for 30 minutes while stirring with a rotating blade rotating at 160 rpm to obtain lime milk. Next, silica powder (Izu silica special powder D) as a siliceous raw material is added to the obtained lime milk so that the CaO / SiO ₂ molar ratio is 1.0, and at the same time, the total of quick lime and silica powder 30 times the amount of water was added to make a uniform slurry, and the mixture was hydrothermally reacted for 4 hours at 16 kg / cm ² in the container while stirring at 120 rpm in an autoclave. Solids in the obtained slurry were substantially composed of zonotolite crystals, and formed spherical secondary particles having a diameter of 30 to 130 μm in which a large number of acicular crystals as primary particles were gathered.

(Preparation of slurry)
5 parts by weight of Portland cement (ordinary Portland cement, manufactured by Ube Mitsubishi Cement Co., Ltd.), 10 parts by weight of glass fibers (CS6J-888S, manufactured by Nittobo Co., Ltd.) 15 parts by weight of small-diameter glass fiber (Q fiber, manufactured by Manville), 0.05 part by weight of a flocculant (Sunfloc N-OP, manufactured by Sanyo Kasei Kogyo Co., Ltd.), and mixed uniformly to make a slurry for papermaking Got. The slurry is made with a long paper making machine to form a paper, then pressed with a pressure of about 4 kgf / cm ² , dried, and a heat insulating paper having a density of 0.35 g / cm ³ and a thickness of 1.4 mm. Got.

(Manufacture of ceramic rollers)
From the heat insulating paper obtained, 267 sheet-like sheet pieces having an outer diameter of 39.5 mm and an inner diameter (diameter of the hollow portion) of 22.5 mm were obtained by punching. In the punching process, a punching machine having a double cylindrical blade was used, and 20 pieces were picked / performed 14 times per time (see FIG. 2). Subsequently, the ring-shaped sheet pieces 11 were successively inserted into the shaft core 4 made of stainless steel having a shaft diameter of 22.0 mm to obtain a laminated body in which 267 divided molded pieces were connected. The insertion load at this time was zero. This laminated body was compressed in the longitudinal direction of the axial center using a flange to obtain a ceramic roller having a heat insulating layer having a length of 300 mm and a bulk density of 0.45 g / cm ³ . The obtained ceramic roller was measured for the gap (X) between the shaft core and the cylindrical body layer, the thermal conductivity of the cylindrical body layer, and the maximum and minimum values of the density of the cylindrical body layer. The results are shown in Table 1. The gap (X) between the shaft core and the cylindrical body layer was performed by the following method. Further, the thermal conductivity of the cylindrical body layer was measured by separately preparing four samples having the same density. Moreover, the maximum value and the minimum value of the density of the cylindrical body layer were obtained from 30 results measured every 10 mm in length of the cylindrical body layer. Moreover, the average value and thermal conductivity difference of the ceramic roller were calculated | required from the result of having measured the surface of the cylindrical body layer ten places. The inner diameter of the cylindrical body layer after assembly (after compression) was 22.5 mm.

(Measurement of gap (X))
Remove the flange of the ceramic roller, take out the block body with a length of 10 mm at an arbitrary part of the cylindrical body layer, compress the block body again to the original length, and then reduce the inner diameter to the minimum display amount. Measurement was performed with a 0.001 mm three-point inner micrometer, and the difference from the outer diameter of the shaft core was halved. The block body was selected from 10 different places in the cylindrical body layer.

  The same method as in Example 1 except that a ring-shaped sheet piece having an outer diameter of 39.5 mm and an inner diameter of 22.2 mm was punched instead of punching a ring-shaped sheet piece having an outer diameter of 39.5 mm and an inner diameter of 22.5 mm. A ceramic roller was prepared and evaluated. The inner diameter of the cylindrical body layer after assembly (after compression) was also 22.2 mm. The results are shown in Table 1.

  Instead of punching a ring-shaped sheet piece having an outer diameter of 39.5 mm and an inner diameter of 22.5 mm, a ring-shaped sheet piece having an outer diameter of 39.5 mm and an inner diameter of 22.1 mm was punched, and the number of stacked ring-shaped sheet pieces A ceramic roller was produced and evaluated in the same manner as in Example 1 except that 267 was changed to 268. The inner diameter of the cylindrical body layer after assembly (after compression) was 22.1 mm. The results are shown in Table 1.

Comparative Example 1
Instead of punching a ring-shaped sheet piece with an outer diameter of 39.5 mm and an inner diameter of 22.5 mm, a ring-shaped sheet piece with an outer diameter of 39.5 mm and an inner diameter of 21.8 mm was punched, and the number of stacked ring-shaped sheet pieces A ceramic roller was prepared and evaluated in the same manner as in Example 1 except that 267 was changed to 266. The results are shown in Table 1.

Comparative Example 2
Instead of punching a ring-shaped sheet piece with an outer diameter of 39.5 mm and an inner diameter of 22.5 mm, a ring-shaped sheet piece with an outer diameter of 39.5 mm and an inner diameter of 21.4 mm was punched, and the number of stacked ring-shaped sheet pieces A ceramic roller was produced and evaluated in the same manner as in Example 1 except that 267 was changed to 265. The results are shown in Table 1.

Comparative Example 3
Instead of punching a ring-shaped sheet piece with an outer diameter of 39.5 mm and an inner diameter of 22.5 mm, a ring-shaped sheet piece with an outer diameter of 39.5 mm and an inner diameter of 22.0 mm was punched, and the number of stacked ring-shaped sheet pieces A ceramic roller was prepared and evaluated in the same manner as in Example 1 except that 267 was set to 265 and an adhesive (“KE1844” manufactured by Shin-Etsu Silicone Co., Ltd.) was interposed at the interface between the shaft core and the cylindrical body layer. Went. The inner diameter of the cylindrical body layer after assembly (after compression) was also 22.0 mm. The results are shown in Table 1.

  Compared with Comparative Example 1, Examples 1 to 3 have no variation in the bulk density of the cylindrical body layer. This is because a gap exists between the shaft core and the cylindrical body layer, so that the insertion resistance (shaft core insertion load) is small, and local variations in density are not caused in the cylindrical body layer. Moreover, compared with the comparative example 3, Examples 1-3 are low in the thermal conductivity of a ceramic roller. This is because a gap exists between the shaft core and the cylindrical body layer. In Comparative Example 2, the shaft core insertion load was high, and the ring-shaped sheet piece was damaged during insertion.

  The ceramic roller obtained in Example 1 was a ceramic roller having an outer diameter of 40 mm and a length of 300 mm, in which a PFA tube having a thickness of 30 μm was further adhered to the peripheral surface of the cylindrical body layer with a silicone rubber adhesive. Then, using a device that presses and heats the ceramic roller for the heating roller with a built-in halogen lamp, the heating roller is operated for 100 hours under the conditions of a heating temperature of 200 ° C., a rotation speed of 100 rpm, and a total load of 30 kgf. When observing the destruction situation, no abnormalities were found.

(A) is sectional drawing of a ceramic roller, (B) is sectional drawing of the cylindrical body layer (laminate) before compression used with the ceramic roller of (A). The figure explaining an example of the process of obtaining a ring-shaped molded piece from a sheet | seat. The figure explaining an example of a compression fixation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical body layer 2 Flange 3 Journal part 4 Metal shaft core 10 Ceramic roller 11 Ring-shaped sheet piece 12 Crevice

Claims (4)

  A ceramic roller used in a heat fixing device of an electrophotographic apparatus using a charged image, comprising a shaft core and a ceramic cylindrical layer formed on an outer peripheral side of the shaft core, the shaft core and the cylindrical body A ceramic roller characterized in that a gap is formed between the layers.   The ceramic roller according to claim 1, wherein the gap (X) satisfies 0.05 ≦ X ≦ 3 mm.   3. The ceramic roller according to claim 1, wherein the cylindrical body layer is divided into 2 to 17 sheets per 10 mm in the longitudinal direction of the axis.   The fixing of the shaft core and the cylindrical body layer is based on a frictional resistance between flanges located on both sides of the shaft core and end faces of the cylindrical body layer. The ceramic roller according to item 1.

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