JP4620623B2 - Ceramic roller and manufacturing method thereof - Google Patents

Description

  The present invention relates to a ceramic roller having a metal shaft core and a cylindrical body layer formed on the outer periphery of the shaft core, and a method for manufacturing the ceramic roller, and particularly to 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 in a heat fixing device and a manufacturing method thereof.

  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).

However, in such a pressure ceramic roller, when the shaft core is made of metal, when the heat fixing roller is heated, stress due to the difference in thermal expansion between the metal shaft core and the ceramic cylindrical body layer is relieved. It is not possible to cause cracks in the cylindrical body layer. Among metals, for example, the thermal expansion coefficient of stainless steel is about 10 to 20 × 10 ⁻⁶ / K, and the thermal expansion coefficient of ceramics is about 3 to 8 × 10 ⁻⁶ / K. This difference often causes a problem of causing cracks and defects in the ceramic cylindrical layer.

  Japanese Laid-Open Patent Publication No. 2-261922 discloses a viscoelastic body serving as an intermediate layer in a composite roller composed of a metal shaft core and a ceramic layer. The stress caused by the difference in thermal expansion between the metal and the ceramic layer during heating of the roller. It is disclosed that the cracking of the ceramic layer is prevented by relaxing. However, since the viscoelastic body serving as the intermediate layer in this composite roller is used at a relatively low temperature such as 40 to 120 ° C., it is a rubber having no heat resistance or a resin harder than the rubber. is there. In addition, since the intermediate layer made of a viscoelastic material does not have an adhesive function, an adhesive layer using an epoxy or silicone adhesive is provided separately, which complicates the manufacturing process.

On the other hand, Japanese Patent Application Laid-Open No. 54-74950 discloses a heat roll formed by connecting a plurality of cylindrical members made of a positive temperature characteristic thermistor. However, the reason why the plurality of cylindrical members are connected in the heat roll is that the positive temperature characteristic thermistor has poor workability, so that a plurality of cylindrical members with short dimensions that are easy to process are connected according to the required length. Yes, it does not solve the problem of stress strain due to the difference in thermal expansion between the metal shaft core and the ceramic cylindrical body layer in the ceramic roller.
JP 2004-86219 A JP-A-2-261922 JP 54-74950 A

  Accordingly, an object of the present invention is to provide a ceramic roller having a metal shaft core and a porous ceramic cylindrical layer formed on the outer periphery of the shaft core, even when heated to a temperature exceeding 200 ° C. Another object of the present invention is to provide a ceramic roller that does not cause cracks in a cylindrical body layer and a method for manufacturing the same.

  In such a situation, the present inventors have intensively studied, and as a result, the cylindrical body layer containing the zonotlite crystal is compressed in the longitudinal direction of the axial core and fixed to the axial core, and the secondary particles of the zonotlite crystal are crushed. If the ceramic roller is oriented in a direction perpendicular to the longitudinal direction of the shaft core, the cylindrical body layer will elastically deform and follow even if the roller is heated and the metal shaft core is thermally expanded. Does not cause cracks in body layers. In addition, the present inventors have found that a property having a small compression elastic modulus, that is, a large compression elastic range can be used in the compression direction, and a strength property having a high compression elastic modulus can be selectively used as the roller surface strength. It came to be completed.

  That is, the present invention relates to a ceramic roller used in a heat fixing device of an electrophotographic apparatus using a charged image, which is made of a ceramic containing a metal shaft core and a zonotlite crystal formed on the outer periphery of the shaft core. The cylindrical layer is compressed in the longitudinal direction of the axial core and fixed to the axial core, and the secondary particles of the zonotlite crystal are oriented in a direction perpendicular to the longitudinal direction of the axial core. A ceramic roller characterized by being crushed in such a manner is provided.

  The present invention also provides a slurry preparation step of preparing a slurry by mixing raw materials containing secondary particles of zonotolite crystals and water, and a molding step of obtaining a plate-like or columnar shaped body from the slurry by wet press molding or papermaking A step of making a hole in the molded body perpendicular to the orientation direction of the secondary particles of the zonotlite crystal to obtain a molded piece having a hollow portion, passing a shaft core through the hollow portion of the molded piece and And a step of compressing and fixing in the longitudinal direction of the shaft.

  The present invention also provides a slurry preparation step in which a raw material containing secondary particles of zonotolite crystals and water are mixed to prepare a slurry, and the orientation direction of secondary particles of zonotlite crystals from the slurry by a wet press molding method. A molding step of obtaining a cylindrical molded piece having a hollow portion penetrating vertically, and a step of passing the shaft core through the hollow portion of the molded piece and compressing and fixing the molded piece in the longitudinal direction of the shaft core. A feature of the present invention is to provide a ceramic roller manufacturing method.

  The present invention also includes a raw material preparation step for preparing a raw material containing secondary particles of zonotlite crystals to obtain a powder mixture, a molding step for forming a plate-like or columnar shaped body by pressurizing the powder mixture, A step of making a hole perpendicular to the orientation direction of the secondary particles of the zonotlite crystal to obtain a molded piece having a hollow portion; passing the shaft core through the hollow portion of the molded piece; And a step of compressing and fixing the ceramic roller.

  The present invention also provides a raw material preparation step in which a raw material containing secondary particles of zonotlite crystals is prepared to obtain a powdery mixture, and the powdery mixture is pressurized to be perpendicular to the orientation direction of secondary particles of zonotlite crystals. A molding step of molding a cylindrical molded piece having a hollow portion penetrating; and a step of passing the shaft core through the hollow portion of the molded piece and compressing and fixing the molded piece in the longitudinal direction of the shaft core. A method for manufacturing a ceramic roller is provided.

  According to the ceramic roller of the present invention, the ceramic forming the cylindrical body layer is cylindrical even if the roller is heated and the metal shaft core is thermally expanded in the longitudinal direction of the shaft by the compression elasticity in the longitudinal direction of the shaft. Since the body layer elastically deforms and follows, the cylindrical body layer does not generate stress due to the difference in thermal expansion and does not cause cracks. Further, a characteristic having a small compression elastic modulus, that is, a wide compression elastic range can be used in the compression direction, and a strength characteristic having a high compression elastic modulus can be selectively used as the roller surface strength. According to the method for manufacturing a ceramic roller of the present invention, a ceramic roller having a novel structure can be obtained by a relatively simple process.

  The ceramic roller of the present invention comprises a metal shaft core 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 that can withstand use, and examples thereof include iron, stainless steel, aluminum, copper, brass, and carbon steel. The present invention prevents cracking of a cylindrical body layer due to a difference in thermal expansion during heating when the shaft core is made of metal and the outer peripheral cylindrical body layer is made of ceramics.

  In the present invention, the ceramic cylindrical layer formed on the outer periphery of the shaft core is not particularly limited, and those having high heat insulation, high heat resistance, and high strength represented by low thermal conductivity and low heat capacity are suitable. Specifically, it is a ceramic including a flat shape in which secondary particles of zonotolite crystals are crushed (hereinafter also referred to as “flat zonotlite secondary particles”).

  The ceramic containing the flat zonotolite secondary particles as the cylindrical layer will be described below. The zonotlite crystal is one of calcium silicate crystals produced by hydrothermal reaction of a siliceous material and a calcium material in the presence of water. A compact made of zonotlite crystals is lightweight, has a very high specific strength, and is excellent in heat resistance and heat insulation. Moreover, the zonotlite crystals are aggregated and bonded to form secondary particles. Such a crystal can be easily identified by X-ray diffraction on the surface of the cylindrical body layer.

  The secondary particles of the zonotlite crystals have a clear spherical shape, and acicular zonotrite crystals are precipitated in the shape of chestnuts on the surface of the particles, and the inside is in the state of a cavity or close to it. Therefore, when it shape | molds using this secondary particle, it will be very bulky and will have a low thermal conductivity and heat capacity. Moreover, since it couple | bonds together by the self-hardening property of this secondary particle, it has the outstanding intensity | strength even if it is lightweight. Further, the flat zonotrite secondary particles are formed by an operation such as pressurization in the production process.

  In addition to the flat zonotlite secondary particles, the cylindrical body layer may contain a reinforcing material, a filler, a reinforcing fiber, a lightweight aggregate, and the like at any blending ratio as necessary. Examples of the reinforcing material include cement and plaster, examples of the filler include talc, diatomaceous earth, and fly ash. Examples of the reinforcing fiber include glass fiber, ceramic fiber, alumina fiber, wollastonite, pulp, and polypropylene. Examples thereof include fibers, aramid fibers, and carbon fibers. Examples of lightweight aggregates include microsilica, perlite, shirasu balloon, and glass balloon. Moreover, as the compounding quantity, for example with respect to 100 mass parts of secondary particles of a zonotlite crystal, 0-20 mass parts of a reinforcing material, preferably 10-20 mass parts, 0-20 mass parts of a filler, preferably 5 10 to 10 parts by weight, reinforcing fibers 0 to 20 parts by weight, preferably 5 to 10 parts by weight, lightweight aggregate 0 to 20 parts by weight, preferably 5 to 10 parts by weight.

  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 used in the ceramic roller of FIG. The ceramic roller 10 includes a metal shaft core 4 and a ceramic cylindrical body layer 1 in order from the center toward the outside. The shaft core 4 includes a flange 2 that can hold the cylindrical body layer attached to the shaft core 4 from both sides with a predetermined pressing force, and a journal portion 3. The cylindrical body layer 1 is composed of six divided cylindrical body layers 1 a to 1 f having the same physical properties and the same size and connected to each other, and is compressed in the longitudinal direction of the shaft core 4 and fixed to the shaft core 4. The In the present invention, the cylindrical body layer 1 does not need to be divided, and when a divided cylindrical body layer is used, the number of divisions is not limited, and the length of the divided cylindrical body layer in the longitudinal direction of the axial center. The dimensions may be different from each other.

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 not particularly limited, but is not less than the elongation of the length due to thermal expansion in the longitudinal direction of the axial core, preferably not less than the difference in the elongation of the length due to thermal expansion between the axial core and the ceramic in the longitudinal direction of the axial core. It is preferable that the compression length Δl is within the elastic range of the cylindrical body layer 1 from the viewpoint that the effects of the present invention are remarkably exhibited. The upper limit value of the compression length Δl is an elastic limit point obtained from the stress-strain curve (SS curve) of the material in the compression length direction, and can be obtained by a known calculation method.

Specifically, for example, the shaft core 4 is made of SUS having a thermal expansion coefficient of 17.3 × 10 ⁻⁶ / K, the cylindrical body layer has a bulk density of 0.3 g / cm ³ , and a thermal expansion coefficient of 3 × 10 ^{− In} the case of a ceramic roller made of ⁶ / K ceramic and having a length of 311 mm at room temperature, SUS expands by 0.91 mm due to thermal expansion at 200 ° C., ceramic expands by 0.16 mm, and the difference of 0.75 mm is the difference between them. Will occur. For this reason, the compression length Δl is set to a length exceeding 0.75 mm. Usually, if the compression length Δl is 1.0 mm or more, it is possible to cover thermal strain caused by a metal having a large thermal expansion coefficient and a metal having a small thermal expansion coefficient. When the compression length Δl is long, stress is applied in the compression direction even during thermal expansion, which is preferable as the roller structure strength. However, when the compression length Δl is too long, the elastic limit of the ceramic is exceeded, and the thermal expansion of the shaft core is caused. Therefore, the elastic deformation of the cylindrical body layer cannot follow.

Further, the flat zonotlite secondary particles in the cylindrical body layer 1 are oriented in a direction perpendicular to the longitudinal direction of the shaft core 4. The orientation of the flat zonotolite secondary particles refers to the direction in which the flat longitudinal direction extends. The characteristics of the cylindrical body layer 1 associated with the specific orientation of the flat zonotolite secondary particles will be described with reference to FIGS. FIG. 2 is a diagram showing the relationship between the bulk density and compressive strength of three ceramics having a bulk density of 0.23, 0.33, and 0.43 g / cm ³ , and FIG. 3 is the relationship between the bulk density and compressive elastic modulus of similar ceramics. FIG. 4 is a diagram showing the relationship between the compression length and the surface pressure (surface pressure during axial core compression). In each figure, the symbol ◆ indicates the relationship in the longitudinal direction of the axis, and the symbol ■ indicates the relationship in the direction perpendicular to the longitudinal direction of the shaft. As is clear from FIG. 2, in the case of the same bulk density, the compressive strength in the direction perpendicular to the longitudinal direction of the shaft is higher than the compressive strength in the longitudinal direction of the shaft. Thus, a durable roller having high roller surface strength can be obtained. As is clear from FIG. 3, in the case of the same bulk density, the elastic modulus in the direction perpendicular to the longitudinal direction of the axial core is higher than the elastic modulus in the longitudinal direction of the axial core. That is, it can be seen that the elasticity is large. As is clear from FIG. 4, in the case of the same surface pressure, the compression length in the longitudinal direction of the shaft core is larger than the compression length in the direction perpendicular to the longitudinal direction of the shaft core. In this case, the surface pressure is small in the longitudinal direction of the shaft core. Therefore, when the roller is assembled, it is easy to increase the compression length in the longitudinal direction of the shaft core. As described above, in the ceramic roller of the present invention, the cylindrical body layer accompanying the specific orientation of the flat zonotlite secondary particles has a high compressive strength in the direction perpendicular to the longitudinal direction of the axial core, and the compressive elastic modulus in the longitudinal direction of the axial core is The elastic modulus is smaller than the compression elastic modulus in the direction perpendicular to the longitudinal direction of the shaft, that is, the elastic range is large in the longitudinal direction of the shaft, and the advantageous characteristic is that the compression length can be increased.

  It can be observed in the SEM photograph of the ceramics that the flat zonotolite secondary particles are oriented in the direction perpendicular to the longitudinal direction of the axial core 4 in the cylindrical body layer 1, and the compression modulus is Since the longitudinal direction of the core and the direction perpendicular to the longitudinal direction of the axial core are greatly different, it can also be confirmed by measuring the compression elastic modulus.

The bulk density of the ceramic of the cylindrical body layer is 0.05 to 0.7 g / cm ³ , preferably 0.2 to 0.4 g / cm ³ . 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 ). The thermal conductivity of the ceramic of the cylindrical body layer is 0.01 to 0.15 W / (m · K), preferably 0.06 to 0.09 W / (m · K).

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. The thermal conductivity (W / m · K) is a rapid thermal conductivity meter in accordance with JIS R2618 unsteady hot wire method on the surface of a flat plate-shaped specimen having a width of 100 mm, a thickness of 20 mm, and a length of 50 mm. It is measured at room temperature using 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 provision of a stress relaxation layer between the shaft core and the cylindrical body layer does not cause cracks in the cylindrical body layer even more stably even when heated to a high temperature. Is preferable. Although it does not restrict | limit especially as a stress relaxation layer, Hardness is 10-90 by durometer A, Preferably it is 20-50, More preferably, it is 20-30, and it can achieve both adhesion | attachment and thermal stress relaxation. This is preferable. In general, an index of rubber flexibility (elasticity) is represented by rubber hardness. If the hardness of the adhesive layer is less than 10 with the durometer A, the adhesiveness is lowered, and if it exceeds 90 with the durometer A, the elasticity to the extent that the stress due to the difference in thermal expansion is relaxed does not appear. The durometer A can be measured by the method specified in JIS K6253 (hardness test method for vulcanized rubber and thermoplastic rubber), and is specified as a type A (medium hardness test) of the durometer hardness test. Is. An example of such an adhesive layer is silicone rubber.

  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.

  Next, the manufacturing method of the ceramic roller of this invention is demonstrated. Examples of the method for producing the ceramic roller of the present invention include a wet method and a dry method. As a wet method, a slurry preparation step of preparing a slurry by mixing raw materials containing secondary particles of zonotolite crystals and water, and a molding step of obtaining a plate-like or columnar shaped body from the slurry by wet press molding or papermaking, A step of making a hole in the molded body perpendicular to the orientation direction of the secondary particles of the zonotlite crystal to obtain a molded piece having a hollow portion; passing a shaft core through the hollow portion of the molded piece; A manufacturing method (first manufacturing method) having a step of compressing and fixing in the longitudinal direction of the core, a slurry preparing step of preparing a slurry by mixing raw materials containing secondary particles of zonotlite crystals and water, and from the slurry A molding step of obtaining a cylindrical molded piece having a hollow portion penetrating perpendicularly to the orientation direction of the secondary particles of the zonotlite crystal by a wet press molding method, and passing the shaft core through the hollow portion of the molded piece; The form piece manufacturing method and a step of fixing by compression in the axial longitudinal direction (second manufacturing method) and the like.

  Also, as a dry method, a raw material preparation step for preparing a raw material containing secondary particles of zonotlite crystals to obtain a powdery mixture, and a molding step for forming a plate-like or columnar shaped body by pressurizing the powdery mixture , A step of making a hole perpendicular to the orientation direction of the secondary particles of the zonotlite crystal to obtain a molded piece having a hollow portion, passing the shaft core through the hollow portion of the molded piece, and passing the molded piece in the longitudinal direction of the shaft core And a raw material preparation step for preparing a raw material containing secondary particles of zonotolite crystals to obtain a powdery mixture, and pressurizing the powdery mixture. A molding step of forming a cylindrical molded piece having a hollow portion penetrating perpendicularly to the orientation direction of the secondary particles of the zonotlite crystal, and passing the shaft core through the hollow portion of the molded piece and extending the molded piece in the longitudinal direction of the shaft core Compressing and fixing in the direction Manufacturing method of (fourth method for manufacturing a) can be mentioned.

  In the slurry preparation step of the first production method, the secondary particles of zonotlite crystals are obtained through a crystallization step of obtaining calcium silicate zonotlite crystals. In the crystallization step, in order to produce zonotlite crystals, the temperature conditions, pressure conditions, and stirring conditions in the autoclave may be set as appropriate. The primary particles of zonotlite crystals form needle-like crystals, and the primary particles form spherical secondary particles having a diameter of 10 to 150 μm. In addition, the primary particles are aggregated and further combined to form spherical secondary particles having a hollow or close to the inside, and acicular zonotolite crystals are precipitated on the surface of the secondary particles in the form of chestnuts. To do. In addition, the form of a primary particle and a secondary particle can be confirmed with a scanning electron microscope etc.

In order to obtain a zonotolite crystal suitable as a calcium silicate crystal, the siliceous raw material and the calcareous raw material are stirred with a large amount of water, usually 20 to 40 times the total amount of the siliceous raw material and the calcareous raw material. In the autoclave, hydrothermal synthesis is performed at a saturated vapor pressure of 7 to 20 kg / cm ² , preferably 13 to 17 kg / cm ² . Further, the siliceous material and the calcareous material may be prepared by adjusting CaO / SiO ₂ to a molar ratio of usually 0.8 to 1.2, preferably 0.9 to 1.1.

The siliceous material is not particularly limited as long as SiO ₂ is contained as a component, and examples thereof include silica and fused silica. Among these, it is preferable to use a crystalline material, particularly silica stone, in that a zonotlite crystal can be generated. Further, it is preferable to use fine powder having an average particle diameter of 5 to 15 μm. As a calcareous raw material, if CaO is contained as a component, there will be no restriction | limiting in particular, For example, slaked lime, quicklime, etc. are mentioned. Among these, it is preferable to use quick lime in that the zonotlite crystals can be sufficiently grown.

  In the slurry preparation step, the slurry may further contain a reinforcing material, a filler, a reinforcing fiber, or a lightweight aggregate as an optional component in addition to the secondary particles of the zonotlite crystals. By adding such an optional component, a molded article containing secondary particles of zonotlite crystals with higher strength can be obtained. Examples of the inorganic fiber, the reinforcing material, the filler, and the lightweight aggregate are the same as those described in the description of the ceramic that is the cylindrical body layer.

The forming step is a step of obtaining a plate-like or columnar shaped body from the slurry by wet pressing or papermaking. In addition, the forming step is 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 size in the longitudinal direction of the flat shape of the zonotlite secondary particles is 100 to 120 μm, and the size in the thickness direction is 20 to 40 μm. When the density of the desired molded body is less than 0.5 g / cm ³ , a wet press (dehydration press) molding method in which molding is performed from a slurry state with a large amount of water is preferable. According to the wet press molding method, due to the self-curing action of the zonotlite secondary particles, even if the bulk density is relatively low such as 0.05 to 0.5 g / cm ³ , the thermal conductivity is 0.01 to 0.00. A molded body having 1 W / (m · K) and a compressive strength of 1 to 10 Mpa, and further having a thermal conductivity of 0.06 to 0.09 W / (m · K) and a compressive strength of 3 to 5 Mpa can be obtained. What is necessary is just to adjust the density of a molded object by changing the bulkiness of the zonotlite crystal secondary particle in a slurry, and the molding pressure at the time of dehydration molding. For example, when the zonotolite crystal secondary particles are made bulky, a molded product 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 molding pressure is usually 1 to 100 kgf / cm ² , preferably 10 to 70 kgf / cm ² , and the time is usually 1 to 30 minutes, preferably 5 to 10 minutes. In addition, the orientation direction of the flat zonotlite secondary particles is perpendicular to the pressing direction in the case of the wet pressing method, and is perpendicular to the direction in which water drops by gravity from the paper making machine in the case of the paper making method. Moreover, a plate-shaped molded object is obtained by papermaking or a wet press, and a columnar molded object is obtained by a wet press. Examples of the column shape include a polygonal column such as a quadrangular column, and a cylinder. The molded body obtained by the above method can be dried by a known technique. The drying conditions are usually 50 to 300 ° C. for 1 to 24 hours, preferably 150 to 250 ° C. for 3 to 10 hours.

  The step of obtaining a molded piece having a hollow portion is a step of making a hole perpendicular to the orientation direction of the flat zonotlite secondary particles in the molded body obtained in the molding step, an example of which is shown in FIG. I will explain. FIG. 5 is a diagram for explaining a step of forming a hole in a plate-like molded body obtained by a wet pressing method. In FIG. 5, the direction indicated by the symbol X, that is, the thickness direction of the plate-shaped molded body 5 is the pressing direction of the plate-shaped molded body 5. Therefore, in the plate-like molded body 5, the flat zonotlite secondary particles are oriented in the direction perpendicular to the pressing direction. In FIG. 5, in the columnar molded pieces 6a, 6b,... Having a quadrangle 55 whose one side in plan view is the same as or slightly larger than the outer diameter of the cylindrical body layer, an axis is formed at the center of the quadrangle. Hollow portions 7a, 7b... Having an inner diameter into which the core 4 is fitted are opened. In this step, after hollow portions 7a, 7b,... Are formed in the plate-shaped molded body 5, the molded pieces 6a, 6b,... May be obtained by cutting along the cutting lines 51, 52. After the plate-shaped molded body 5 is cut along the cutting lines 51, 52 to obtain the molded pieces 6a, 6b,..., The hollow portions 7a, 7b,. Next, for example, as shown in FIG. 6, the molded piece 6a is inserted into the metal shaft core 4, then the molded piece 6b is inserted next, and a predetermined number of molded pieces are sequentially inserted. The outer periphery of the molded pieces 6a to 6f is cut and fixed in the longitudinal direction, and then a cylindrical molded body in which six divided cylindrical body layers are connected by end faces is obtained. In the conventional ceramic roller, since the cylindrical body layer is a single body, it is necessary to form the hollow portion 71 in a direction perpendicular to the pressing direction X of the plate-like molded body 5 as shown in FIG. In this case, when the roller was formed, the orientation of the flat zonotlite secondary particles in the circumferential direction was anisotropic and non-uniform. Moreover, the process which forms a hollow part in a longitudinal direction is not easy. On the other hand, according to the present invention, the orientation of the flat zonotolite secondary particles in the circumferential direction is uniform with no anisotropy. Moreover, it is easy to form a hollow part with a short length. Moreover, a molded piece with a short length can also be obtained from cylindrical wet press molding.

  As a method of compressing and fixing the molded pieces 1a to 1f so as to have a predetermined compression length Δl in the longitudinal direction of the axis (see FIGS. 1 and 6), for example, a method of screwing a flange with a female screw, or Examples include a method of fixing the press-fitted molded 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 and the pressing force between the peripheral surface 41 of the shaft core 4 and the inner peripheral surface 11 of the cylindrical body layer 1. Therefore, the adhesive between the shaft core 4 and the cylindrical body layer 1 may not be used. The pressing force between the peripheral surface of the shaft core and the inner peripheral surface of the cylindrical body layer 1 is perpendicular to the longitudinal direction of the axial core as well as to the longitudinal direction of the axial core due to the compression between the flanges 2. A compressive force is also applied in the direction, and the pressing force between the peripheral surface of the shaft core and the inner peripheral surface of the cylindrical body layer 1 becomes strong.

  In the first production method, the firing (autoclave) step is an optional step, but when performing the firing step, it is preferable to obtain a molded piece after firing in that no dimensional change occurs. Further, when the molded piece is compressed and fixed in the longitudinal direction of the shaft core, an adhesive such as silicone rubber can be injected between the shaft core and the molded piece to form a stress relaxation layer. . Further, after mounting the molded piece on the shaft core, the outer periphery of the cylindrical body layer may be further coated with a surface layer such as a fluororesin layer such as a film of PFA resin, a silicone rubber layer, or a glass layer by a known method. it can.

  Next, the second manufacturing method will be described. In the second manufacturing method, the same components as those in the first manufacturing method are the same, and thus the description thereof will be omitted and different points will be described. That is, the second manufacturing method is different from the first manufacturing method in that the step between the slurry preparation step and the step of compressing and fixing the molded piece in the longitudinal direction of the axial center is performed from the slurry by wet press molding. Thus, the molding step is to obtain a cylindrical molded piece having a hollow portion penetrating perpendicularly to the orientation direction of the flat zonotlite secondary particles.

  In the molding step, a cylindrical molded piece having a hollow portion is directly obtained. Such a molding step includes a step of arranging the shaft core in the mold, a step of pouring slurry between the mold and the shaft core, and a step of obtaining a molded piece by pressing in the longitudinal direction of the shaft core in the mold. The shaft core integral molding method which has these is mentioned. An example of the process will be described with reference to FIG. The molding die 9 is a center 91 in the radial direction of the cylindrical outer cylinder 93 and extends in the axial direction, and a pair of disk-like pieces that are movably installed in the axial direction through the axial core 91. And a press plate 92. The press plate 92 forms and dewaters the slurry and has a porous structure. Slurry is poured into a space surrounded by the outer cylinder 93, the shaft core 91, and the molding plate 92, and the molding piece 1a is obtained while dehydrating by pressing in the longitudinal direction of the shaft core (symbol X direction) by the press plate 92 in the molding die. After obtaining the molding piece 1a, as shown in FIG. 8, the slurry is further poured into the space between the molding piece 1a and the press plate 92, and molding is performed while dehydrating by pressurizing in the axial direction (symbol X direction). A piece 1b is obtained, and this operation is sequentially performed to obtain cylindrical shaped pieces 1a, 1b,... In a mold.

  In the third manufacturing method, the same components as those in the first manufacturing method are the same, and thus the description thereof will be omitted and different points will be described. That is, the third manufacturing method is different from the first manufacturing method in that it is a dry method that does not use water, and a press method is used. That is, the raw material used in the raw material preparation step is the same as the raw material used in the first manufacturing method, and is a powder obtained by drying the slurry. The blending amount of each raw material is the same as the blending description in the ceramic. The secondary particles of the zonotlite crystals obtained in the crystallization step are oriented in a flat shape by pressurization and develop strength due to the entanglement of the zonotrite needle-like crystals. Therefore, even a dry molding method can be used.

  In the third production method, the density may be adjusted by combining the molding pressure, secondary particles of zonotolite crystals, a filler, and a lightweight aggregate. As a mixing apparatus used in the raw material preparation step, a kneading apparatus can be used, and examples thereof include a Henschel mixer, a double-arm kneader, a high-speed mixer, a butterfly mixer, and the like, and any known apparatus can be used as appropriate. In addition, the orientation direction of the flat zonotolite secondary particles is a direction perpendicular to the pressing direction.

  In the fourth manufacturing method, the same components as those in the second manufacturing method are the same, and thus the description thereof will be omitted and different points will be described. That is, the fourth manufacturing method is different from the second manufacturing method in that it is a dry type that does not use water. That is, since the dried secondary particles of the powdered zonotlite crystals are strongly bonded, the cylindrical mold shown in FIGS. 7 and 8 can be used. Further, the molding step of the fourth manufacturing method includes a step of arranging the shaft core in the molding die, a step of supplying a powder mixture between the molding die and the shaft core, and a longitudinal direction of the shaft core in the molding die. It is also possible to employ a shaft core integral molding method including a step of obtaining a molded piece by pressing. In addition, the orientation direction of the flat zonotolite secondary particles is perpendicular to the pressing direction, as in the third production method.

  Since the ceramic roller of the present invention has a small bulk density and a small heat capacity and thermal conductivity, the heat insulating property 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. In Examples and Comparative Examples, each evaluation item shown in Table 1 was measured by the following test method.

(1) Bulk density (g / cm ³ ): Calculated from the mass of the test piece and the volume calculated from the shape dimensions.
(2) Compressive strength: Press surface compressive strength is compressive strength in the press surface direction, and interlayer compressive strength is compressive strength in a direction perpendicular to the press surface direction, and is measured in accordance with JIS R1608.
(3) Compressive elastic modulus: Press surface compressive elastic modulus is a compressive elastic modulus in the press surface direction, and interlayer compressive elastic modulus is a compressive elastic modulus in a direction perpendicular to the press surface direction. It is calculated from the stress ((stress σ / strain ε) (MPa)).
(4) Rubber hardness: As a test piece, a cylindrical test piece having a diameter of 40 mm and a thickness of 10 mm is separately prepared and measured in accordance with a test method for medium hardness of type A in the durometer hardness test of JIS K6253. It is a thing.
(5) Roller heating test: A roller is placed in a constant temperature oven ("DN610" manufactured by Yamato Kagaku Co., Ltd.), heated to a predetermined heating temperature at a heating rate of 40 ° C / hour, held for 1 hour, and then the cooling rate The temperature is lowered to 100 ° C. at 40 ° C./hour, the roller is taken out from the thermostat, and the presence or absence of cracks in the cylindrical body layer is visually observed. The predetermined heating temperature is 100, 200 and 300 ° C., respectively.
(6) Rotating heating test: A heating roller with a halogen lamp built in is used to press and rotate a ceramic roller as a sample. The heating temperature of the heating roller is 200 ° C., the rotation speed is 100 rpm, and the total load is 30, 60, 90 kgf. It is operated for 100 hours under the conditions, and the state of destruction of the cylindrical body layer is observed.

(Formation of zonotlite crystals)
Quick lime (150 mesh Adachi quick lime) as a calcareous raw material was put into 24 times amount of 90 ° C. hot water and digested for 30 minutes while stirring with a stirring blade rotating at 160 rpm to obtain lime milk. Subsequently, 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 a pressure of 16 kg / cm ² while stirring at 120 rpm in an autoclave. The solid in the obtained slurry was 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 aggregated.

(Slurry adjustment)
7 parts by weight of Portland cement (“ordinary Portland cement”; manufactured by Ube Mitsubishi Cement Co., Ltd.) and 5 parts by weight of glass fiber (“ECS131-33G”) per 100 parts by weight of secondary particles of zonotlite crystals in the slurry (Manufactured by Glass Co., Ltd.) and 100 ppm of a flocculant (“San Flock N-OP” manufactured by Sanyo Chemical Industries) were added and mixed to obtain a slurry for dehydration press molding. The slurry was poured into a mold, subjected to wet press molding at a molding pressure of 10 kgf / cm ² , and then dried at 200 ° C. for 24 hours to obtain a plate-like molded body having a length of 300 mm, a width of 300 mm, and a thickness of 60 mm.

(Manufacture of ceramic rollers)
As shown in FIG. 5, an inner diameter hole is processed in the pressing direction from the obtained plate-like molded body, and a hollow column having an inner diameter of 29.0 mm is formed in a prismatic product having a length of 50 mm, a width of 50 mm, and a length (thickness) of 60 mm. Five molded pieces in which the part was formed were produced. Next, the hollow portions of the five molded pieces were inserted into a stainless steel shaft core to obtain a structure in which the five divided molded pieces were connected. Next, the flange was press-fitted so that the compression length was 3 mm. After confirming that the molded piece was fixed to the shaft core, the outer diameter of the molded piece was ground to obtain a cylindrical body layer having a thickness of 5.47 mm. The compression length of 3 mm is larger than the thermal strain at 300 ° C. of the stainless steel shaft and smaller than the elastic limit of the ceramic. Further, a PFA tube having a thickness of 30 μm was adhered to the peripheral surface of the cylindrical body layer with a silicone rubber adhesive to obtain a ceramic roller having an outer diameter of 40 mm and a length of 297 mm.

  The bulk density, thermal conductivity, press surface compressive strength, press surface compressive elastic modulus, interlaminar compressive strength and interlaminar compressive elastic strength of the plate-like molded body are measured by the above-mentioned methods. And the rotary heating test was conducted, and the results are shown in Table 1. As a result, in Example 1, in the roller heating test, the cylindrical body layer did not crack even when heated to 300 ° C. Further, in the rotary heating test, the destruction of the cylindrical body layer was not observed under a load of 30 kgf at 200 ° C., which is considered to be no problem if this condition is cleared in practice. Further, FIG. 9 shows an SEM photograph viewed from above the plate-shaped molded body of FIG. 5, that is, viewed from the surface 55, and viewed from the front of the plate-shaped molded body of FIG. The SEM photograph which was seen is shown in FIG. From the SEM photograph in FIG. 9, the flat surface of the flat zonotlite secondary particles is observed, and in FIG. 10, since the side surface is observed in the flat shape of the flat zonotlite secondary particles, the flat longitudinal direction is It can be seen that the film is oriented in the direction perpendicular to the pressing direction.

Instead of the bulk density of 0.25 g / cm ³ of the plate-shaped molded body of Example 1, 0.33 g / cm ³ was used. That is, except that the 40 kgf / cm ² by increasing the slurry pouring amount and instead the molding pressure to 10 kgf / cm ² was carried out in the same manner as in Example 1. The results are shown in Table 1. As a result, in Example 2, in the roller heating test, the cylindrical body layer did not crack even when heated to 300 ° C. Further, in the rotary heating test, no destruction of the cylindrical body layer was observed under a load of 30 kgf and 60 kgf at 200 ° C., respectively.

Instead of a bulk density of 0.25 g / cm ³ of the plate-shaped molded article of Example 1, in which a 0.43 g / cm ^3. That is, the same procedure as in Example 1 was performed, except that the slurry pouring amount was increased and the molding pressure was changed to 70 kgf / cm ² instead of 10 kgf / cm ² . The results are shown in Table 1. As a result, in Example 3, in the roller heating test, the cylindrical body layer did not crack even when heated to 300 ° C. Further, in the rotary heating test, no destruction of the cylindrical body layer was observed under loads of 30 kgf, 60 kgf, and 90 kgf at 200 ° C.

Comparative Example 1
As shown in FIG. 11, an inner diameter hole is machined in a direction perpendicular to the press direction from a plate-like molded body obtained by the same method as in Example 2, and the length is 50 mm, the width is 50 mm, and the length is 297 mm. A molded body in which a hollow portion having an inner diameter of 29.3 mm was formed in a prismatic product, and then a stainless steel shaft having an outer diameter of 29 mm was inserted into the hollow portion of the molded body. At this time, a silicone rubber adhesive was applied to the peripheral surface of the shaft core, and the shaft core and the cylindrical body layer were bonded by normal temperature curing. After confirming that the molded piece was fixed to the shaft core, the outer diameter of the molded piece was ground to obtain a cylindrical body layer having a thickness of 5.32 mm. Further, a PFA tube having a thickness of 30 μm was adhered to the peripheral surface of the cylindrical body layer with a silicone rubber adhesive to obtain a ceramic roller having an outer diameter of 40 mm and a length of 297 mm.

  Various physical properties of the plate-like molded body were measured in the same manner as in Example 1, and the ceramic roller was subjected to a roller heating test and a rotational heating test. The results are shown in Table 1. As a result, in Comparative Example 1, a crack occurred in the cylindrical body layer at 200 ° C. in the roller heating test, and in the rotational heating test, breakage occurred between the layers with a load of 60 kgf.

(A) is sectional drawing of a ceramic roller, (B) is sectional drawing of the cylindrical body layer used with the ceramic roller of (A). The figure which is the characteristic of the ceramics accompanying the specific orientation of the secondary particle of a zonotlite crystal, Comprising: The figure which shows the relationship between a bulk density and compressive strength. The figure which shows the relationship between a bulk density and a compression elastic modulus. The figure which shows the relationship between compression length and surface pressure (surface pressure at the time of compression of an axial center longitudinal direction). The figure explaining the process of making a hole in the plate-shaped molded object obtained by the wet press method. The figure explaining the process of assembling the shaping | molding piece obtained in FIG. 5 to an axial center. The figure explaining the shaft core integral molding method. The other figure explaining the shaft core integral molding method. The SEM photograph of the molded object of the prism obtained in the Example. The other SEM photograph of the molded object of the prism obtained in the Example. The figure explaining the hole processing of the plate-shaped molded object obtained by the comparative example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical body layer 1a-1f Division | segmentation cylindrical body layer 2 Flange 3 Journal part 4 Metal shaft core 5 Molded body 6a, 6b Columnar molded piece 7a, 7b Hollow part 9 Molding die 10 Ceramic roller 91 Shaft core 92 Press plate 93 Cylindrical outer cylinder

Claims (14)

  A ceramic roller used in a heat fixing device of an electrophotographic apparatus using a charged image, comprising a metallic shaft core and a ceramic cylindrical layer containing zonotolite crystals formed on the outer periphery of the shaft core. The cylindrical layer is compressed in the longitudinal direction of the axial core and fixed to the axial core, and is crushed so that secondary particles of the zonotlite crystal are oriented in a direction perpendicular to the longitudinal direction of the axial core. A ceramic roller characterized by   2. The ceramic roller according to claim 1, wherein a compression elastic modulus in the longitudinal direction of the axis of the ceramic is smaller than a compression elastic modulus in a direction perpendicular to the longitudinal direction of the axis.   The ceramic roller according to claim 1 or 2, wherein the cylindrical body layer is divided into at least two along the axial direction of the axis.   The ceramic roller according to any one of claims 1 to 3, wherein a compression length in a longitudinal direction of the shaft core is equal to or greater than an extension of a length due to thermal expansion of the shaft core.   The ceramic roller according to any one of claims 1 to 4, wherein a stress relaxation layer is provided between the shaft core and the cylindrical body layer.   The ceramic roller according to any one of claims 1 to 5, further comprising a surface layer made of a fluororesin on an outer periphery of the cylindrical body layer.   The ceramic roller according to claim 1, wherein the zonotlite crystal forms spherical secondary particles having a diameter of 10 to 150 μm. The cylindrical body layer has a bulk density of 0.05 to 0.7 g / cm ³ and a thermal conductivity of 0.01 to 0.15 W / (m · K). The ceramic roller according to item 1.   A slurry preparation step for preparing a slurry by mixing raw materials containing secondary particles of zonotlite crystals and water, a molding step for obtaining a plate-like or columnar shaped body from the slurry by wet press molding or papermaking, Perforating holes perpendicular to the orientation direction of the secondary particles of the zonotlite crystal to obtain a molded piece with a hollow part, passing the shaft core through the hollow part of the molded piece, and compressing the molded piece in the longitudinal direction of the shaft core And a step of fixing the ceramic roller.   A slurry preparation step for preparing a slurry by mixing a raw material containing secondary particles of zonotrite crystals and water, and a hollow portion penetrating perpendicularly to the orientation direction of the secondary particles of the zonotlite crystals from the slurry by a wet press molding method A ceramic roller comprising: a molding step of obtaining a cylindrical molded piece comprising: a step of passing a shaft core through a hollow portion of the molded piece and compressing and fixing the molded piece in the longitudinal direction of the shaft core Production method.   The molding step includes a step of arranging a shaft core in the mold, a step of pouring slurry between the mold and the shaft core, and a step of obtaining a molded piece by pressing in the longitudinal direction of the shaft core in the mold. The method for producing a ceramic roller according to claim 10, comprising:   A raw material preparation step of preparing a raw material containing secondary particles of zonotlite crystals to obtain a powdery mixture, a molding step of pressing the powdery mixture to form a plate-like or columnar shaped body, and a secondary of the zonotlite crystals A step of making a hole perpendicular to the orientation direction of the particles to obtain a molded piece having a hollow portion, and a step of passing the shaft core through the hollow portion of the molded piece and compressing and fixing the molded piece in the longitudinal direction of the shaft core A method for producing a ceramic roller, comprising:   A raw material preparation step for preparing a raw material containing secondary particles of zonotrite crystals to obtain a powdery mixture, and a hollow portion that pressurizes the powdery mixture and penetrates perpendicularly to the orientation direction of the secondary particles of the zonotlite crystals A ceramic roller comprising: a molding step of molding a cylindrical shaped piece, and a step of passing the shaft core through the hollow portion of the molded piece and compressing and fixing the molded piece in the longitudinal direction of the shaft core. Method. The molding step includes a step of arranging a shaft core in the mold, a step of supplying a powder mixture between the mold and the shaft core, and pressing in the longitudinal direction of the shaft core in the mold to obtain a molded piece. The method for manufacturing a ceramic roller according to claim 13, further comprising a step.

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