JP4463669B2 - Ceramic roller - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic roller having a shaft core and a cylindrical body layer formed on the outer periphery of the shaft core, and more particularly, to a roller used in a heat fixing device mounted on an electrophotographic apparatus such as an electronic copying machine, a printer, and a facsimile machine. .

  Electrophotographic devices such as electrostatic copiers and laser printers, which are essential equipment in information technology, project optical images onto the surface of a uniformly charged photoconductor in the dark, and the optical surface corresponds to the optical image. An electrostatic latent image is formed, and charged fine particles (toner) as a developer are spread on the surface of the electrostatic latent image, and the image is developed by electrostatic force. The image is developed on the surface of the photoconductor with a polarity opposite to that of the charged fine particles. The surface of the charged printing paper is overlapped to transfer the fine particles onto the paper surface, and the fine particles on the paper surface are heated and melted under pressure by a heat fixing roller (hereinafter also referred to as a heat roller) for heat fixing on the paper surface. By doing this, it is a device that duplicates images.

  As the heat fixing device portion for fixing the toner on the paper surface with the heat fixing roller, one composed of two rollers, a heat fixing roller and a pressure roller, is generally known. Then, the fine particles on the paper surface are fused and heat-fixed by being heated while being pressed by the heat-fixing roller supported by the pressure roller and heated from the surface side.

  The heat fixing roller is heated to a high temperature that can be fused in order to fuse the toner onto the paper surface as described above. However, when the heat fixing operation is performed, printing always at a temperature much lower than the heat fixing temperature is performed. Since the paper and the pressure roller are in close contact with each other and rotate, at that moment, a large amount of heat energy is taken away from the close contact portion with the pressure roller and cooled.

On the other hand, the pressure roller has a low temperature (usually room temperature) at the start of printing, particularly when starting to use the heat fixing device, so that the difference from the required temperature of the heat fixing roller is large. It is necessary to heat it to a higher temperature in anticipation of the above-mentioned close cooling, and as a result, not only the power consumption is increased and the energy efficiency is low, but also the printable temperature is expected to be cooled. Warming up time (standby time) for raising the temperature to a long time is not only low in time efficiency, but also causes discomfort for the user.

In addition, the pressure roller is required to have heat resistance because it is in close contact with the high-temperature heat fixing roller. On the other hand, the amount of energy taken away from the heat fixing roller by the pressure roller is added considering a long time. Considering only the heat capacity of the pressure roller and a short time, it is affected by the thermal conductivity. Both of these characteristics are commonly related to the bulk density of the cylindrical body layer. Considering these circumstances, a roller made of silicone rubber sponge having excellent heat insulation has been used as a pressure roller. Further, it has been proposed that the cylindrical body layer is constituted by a heat insulating layer made of a molded body having a high porosity such as a porous ceramic material or a porous resin molded body (for example, Patent Document 1).
JP 2004-86219 A (Claim 1)

  However, such a molded article having a high porosity has a high density in order to obtain a strength that can withstand use, and there is a limit to obtaining a roller that satisfies both the heat resistance and strength characteristics. . That is, when a ceramic material is used, it is conceivable that the bulk density is lowered as a means for lowering the thermal conductivity, but if the bulk density is lowered, there is a concern that the strength becomes weak. Further, when a silicone rubber sponge is used, there is a concern that the resin itself may be thermally deteriorated when used for a long time, and the diameter of the roller may be changed.

In recent years, further reduction of power consumption has been demanded. The fixing roller and pressure roller use inexpensive and strong metal shaft cores and shaft pipes such as aluminum and stainless steel. These metals have high heat conductivity and high heat capacity, so they have poor heat insulation and are consumed. This hinders further reduction of power.
Furthermore, in the rollers used in fixing devices other than the fixing roller and the pressure roller, for example, a roller such as a driving roller, a peeling roller, a tension roller, and a guide roller, the roller itself often has a relatively small diameter. Therefore, high strength is required. Therefore, in order to further reduce power consumption, a material replacing metal is strongly demanded.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a ceramic roller having low thermal conductivity and high strength and a method for manufacturing the same.

  In such a situation, the present inventors have conducted extensive studies, and as a result, there is room for improvement in the material of the cylindrical body layer. By using calcium silicate as a main component, a cylindrical body layer mainly composed of a conventional silicone sponge. As a result, the inventors have found that the heat insulation (low thermal conductivity, low heat capacity), high heat resistance, high strength, and the like are achieved, and the present invention has been completed.

That is, the first invention of the present application is characterized in that in the roller including the shaft core and the cylindrical body layer formed on the outer periphery of the shaft core, the cylindrical body layer is made of ceramics mainly composed of calcium silicate. A ceramic roller (hereinafter also referred to as a first embodiment) is provided. Preferably, the cylindrical body layer is composed of a molded body (hereinafter also referred to as a first molded body) obtained by molding and drying calcium silicate crystals obtained in advance by hydrothermal synthesis. The main component of calcium acid is zonotolite crystals. The cylindrical body layer may be composed of a molded body (hereinafter also referred to as a second molded body) made of calcium silicate crystals obtained by hydrothermal synthesis after molding. In this case, preferably, the main component of the calcium silicate crystal is a zonotlite crystal, a tobermorite crystal, or an amorphous C—S—H crystal. In the first invention of the present application, preferably, the bulk density of the cylindrical body layer is 0.05 to 1.5 g / cm ³ , and more preferably, the thermal conductivity of the cylindrical body layer is 0.01 to 0.5 W / (m · K). Further, a surface layer covered with the cylindrical body layer and containing a fluororesin may be further provided, and an intermediate layer made of an elastic body may be further provided between the cylindrical body layer and the surface layer. A first invention of the present application provides the ceramic roller used in a heat fixing device of an electrophotographic apparatus.

  According to a second aspect of the present invention, there is provided a ceramic roller (hereinafter referred to as a second roller) used in a heat fixing device of an electrophotographic apparatus, wherein the shaft core is made of ceramics mainly composed of calcium silicate. (Also referred to as a form). A cylindrical body layer made of ceramics mainly composed of calcium silicate may be further formed on the outer periphery of the shaft core.

The third invention of the present application is
A1) obtaining calcium silicate crystals by heating a siliceous raw material and a calcareous raw material together with a large amount of water to a high temperature in an autoclave;
B1) forming a calcium silicate crystal-containing shaped body from the slurry containing the calcium silicate crystals;
D1) forming a cylindrical body layer made of the calcium silicate crystal-containing formed body on the outer periphery of the shaft core, and a ceramic roller manufacturing method (hereinafter also referred to as a first manufacturing method of the first embodiment). ). Preferably, the calcium silicate crystal is a zonotlite crystal, the primary particles of the zonotlite crystal form needle-like crystals, and the primary particles form spherical secondary particles having a diameter of 10 to 150 μm.
The fourth invention of the present application is
A2) a step of obtaining a calcium silicate crystal precursor by heating a siliceous raw material and a calcareous raw material together with a large amount of water in an autoclave to a high temperature;
B2) forming a calcium silicate crystal precursor-containing molded body from a slurry containing the calcium silicate crystal precursor;
C2) heating the calcium silicate crystal precursor-containing molded body to a high temperature in an autoclave to produce calcium silicate crystals to obtain a calcium silicate crystal-containing molded body;
D2) A method for producing a ceramic roller, comprising: forming the calcium silicate crystal precursor-containing molded body or a cylindrical body layer made of the calcium silicate crystal-containing molded body on an outer periphery of an axis. (Also referred to as a second manufacturing method of the first form).
The fifth invention of the present application is
A3) obtaining a kneaded material containing a siliceous raw material, a calcareous raw material, a molding aid, and water;
B3) a step of extruding an amorphous-containing molded body from the kneaded product;
C3) heating the amorphous-containing shaped body to a high temperature in an autoclave to produce calcium silicate crystals to obtain a calcium silicate crystal-containing shaped body;
D3) forming a cylindrical body layer made of the amorphous-containing molded body or the calcium silicate crystal-containing molded body on the outer periphery of the shaft core, and a ceramic roller manufacturing method (hereinafter referred to as a first embodiment) The third manufacturing method).

The ceramic roller of the present invention has low thermal conductivity and high strength, and is suitable as a roller used in a heat fixing device of an electrophotographic apparatus. Moreover, since the heat capacity is 30 to 80% lower than that of conventional rollers, the heat insulation is high and the power consumption can be reduced.
Further, according to the method for producing a ceramic roller of the present invention, a ceramic roller having a low thermal conductivity and high strength calcium silicate as a main component can be obtained, and a ceramic roller excellent in heat insulation, heat resistance, and durability is suitable. Can get to.

  In the present invention, the ceramic roller is not particularly limited in its application, but refers to a roller suitably used in a heat fixing device of an electrophotographic apparatus such as a printer or a copying machine, specifically, For example, a heat fixing roller provided with a heating unit, a pressure roller disposed relative to the heat fixing roller, a driving roller connected to a driving unit in the heat fixing device, a fixing roller, or a heating roller used in the heat fixing device. The separation roller that assists the separation of the recording medium such as the recording paper from the pressure roller, the tension roller that bridges the belt between the fixing roller or the pressure roller when the fixing belt is used in the thermal fixing device, and the movement of the fixing belt The guide roller etc. to regulate can be mentioned.

  The ceramic roller of the present invention will be described below, but this is merely an example and does not limit the present invention.

  First, a ceramic roller according to a first embodiment of the present invention will be described with reference to FIGS. 1 is a radial sectional view of a ceramic roller according to the first embodiment of the present invention, FIG. 2 is an axial sectional view of the ceramic roller according to the first embodiment of the present invention, and FIG. It is sectional drawing of the radial direction of the ceramic roller which is 1st other embodiment.

  In FIG. 1, a ceramic roller 10 includes a shaft core 11 and a cylindrical body layer 12 formed on the outer periphery of the shaft core 11.

  The shaft core 11 is not particularly limited as long as it has sufficient rigidity to withstand use, and a known shaft core or shaft pipe can be used. Usually, a metal such as iron, stainless steel, aluminum, copper, or brass is used. Since it meets the required strength and is available at a relatively low cost, it can be used preferably.

The cylindrical body layer 12 is made of ceramics whose main component is calcium silicate. In the present invention, the calcium silicate is not particularly limited as long as it is a compound formed by hydrothermal reaction of a siliceous raw material (SiO ₂ ) and a calcium raw material (CaO) in the presence of water. , Zonotrite crystals, tobermorite crystals, amorphous C—S—H crystals, and the like. In particular, a molded body made of zonotlite crystals is preferable because it is lightweight, has a very high specific strength, and is excellent in heat resistance and heat insulation. The presence or absence of such crystals can be easily determined by X-ray diffraction on the surface of the cylindrical body layer 12 because diffraction peaks peculiar to various crystals are obtained by X-ray diffraction.

  In the present invention, the cylindrical body layer 12 is composed of a first molded body obtained by molding and drying a calcium silicate crystal obtained in advance by hydrothermal synthesis before molding by a manufacturing method described later. Also good. Here, examples of the calcium silicate crystal include a zonotlite crystal, a tobermorite crystal, and an amorphous C—S—H crystal, and two or three of the crystals may be mixed. It is preferable that it is comprised from a zonotolite crystal single-piece | unit. The zonotlite crystals are aggregated and bonded to form secondary particles. As shown in FIGS. 4a and 4b, the secondary particles 15 have a clear spherical shape, and acicular zonotlite crystals are precipitated in chestnut shape on the surface of the particles, and the inside is hollow or close to it. It is in a state. Therefore, when it shape | molds using this secondary particle 15, it will be very bulky and will have a low heat conductivity and heat capacity. Further, since the secondary particles 15 are self-curing and bonded to each other, they have excellent strength despite low thermal conductivity and heat capacity. Further, when pressure is further applied at the time of molding, which will be described later, the zonotrite needle-like crystals are entangled in a complicated manner, resulting in a more excellent structure that achieves both heat insulation and strength.

  In this invention, the cylindrical body layer 12 may be formed from the 2nd molded object which consists of a calcium silicate crystal | crystallization obtained by hydrothermal synthesis after the shaping | molding manufactured with the manufacturing method mentioned later. Here, examples of the calcium silicate crystal include a zonotlite crystal, a tobermorite crystal, and an amorphous C—S—H crystal, and the second molded body is preferably composed of one crystal as much as possible. Two or three of the above crystals may be mixed. According to such a molded body, by forming the crystal, it is possible to obtain a strong bond over the entire molded body. As a result, the obtained molded body is a material having high heat insulation and excellent strength. It becomes.

  In the present invention, the cylindrical body layer 12 is obtained by molding a calcium silicate crystal precursor obtained in advance by hydrothermal synthesis before molding, which is produced by the production method described later, and then obtaining a silica layer obtained by further hydrothermal synthesis. You may be comprised from the 3rd molded object which consists of calcium acid crystals. Here, examples of the calcium silicate crystal precursor include a zonotlite crystal precursor, a tobermorite crystal precursor, and an amorphous C—S—H crystal precursor, and two or three of the crystal precursors are mixed. However, it is preferably composed of one crystal precursor as much as possible, and particularly preferably composed of a single zonotlite crystal precursor.

In addition to calcium silicate, the cylindrical body layer 12 is made of reinforcing materials such as cement and gypsum, fillers such as talc, diatomaceous earth, and fly ash, glass fibers and ceramic fibers, alumina fibers, wollastonite, pulp, polypropylene fibers, and aramid fibers. Further, reinforcing fibers such as carbon fibers, lightweight aggregates such as microsilica, perlite, shirasu balloon, and glass balloon may be optionally added and blended as necessary. Moreover, the unreacted siliceous raw material and the calcareous raw material may be included.
In the case of the first molded body, the blending amount is 0 to 20 parts by mass of a reinforcing material, preferably 10 to 20 parts by mass, and preferably 0 to 20 parts by mass, preferably 100 parts by mass of calcium silicate. 5 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.
Moreover, if it is a 2nd molded object, the compounding quantity is 0-20 mass parts of reinforcing materials with respect to 100 mass parts of calcium silicate, Preferably it is 10-20 mass parts, 0-100 mass parts of fillers, Preferably they are 10-50 mass parts, 0-100 mass parts of reinforcing fibers, Preferably it is 5-30 mass parts, Lightweight aggregate 0-100 mass parts, Preferably it is 10-50 mass parts.

In the present invention, the bulk density of the cylindrical body layer 12 is usually 0.05 to 1.5 g / cm ³ . Can not be obtained intensity bulk density is expected to be less than 0.05 g / cm ^3, exceeds 1.5 g / cm ^3, the thermal conductivity and heat capacity is large, no insulation effect can be obtained to expect Therefore, it is not preferable. Moreover, the preferable range of the bulk density is 0.05 to 0.5 g / cm ³ , more preferably 0.2 to 0.4 g / cm ³ in the case of the first molded body, and the second molded body. if, 0.5~1.5g / cm ^3, more preferably from 0.6 to 1.2 g / cm ^3.

  In the present invention, the thermal conductivity of the cylindrical body layer 12 is usually 0.01 to 0.5 W / (m · K). Moreover, the preferable range of thermal conductivity is 0.01 to 0.1 W / (m · K), more preferably 0.06 to 0.09 W / (m · K) in the case of the first molded body. In the case of the second molded body, it is 0.1 to 0.5 W / (m · K), more preferably 0.15 to 0.35 W / (m · K). If the thermal conductivity is less than 0.01 W / (m · K), the bulk density becomes too low and the expected strength cannot be obtained, and the heat insulation effect expected to exceed 0.5 W / (m · K). Is not preferable.

In the present invention, the heat capacity per cm ³ of the cylindrical body layer 12 is usually 0.04 to 1.2 J / K. If the heat capacity is less than 0.04 J / K, the bulk density becomes too low, the expected strength cannot be obtained, and if it exceeds 1.2 J / K, the expected heat insulation effect cannot be obtained. The preferable range of the heat capacity is 0.04 to 0.4 J / K, more preferably 0.16 to 0.32 J / K for the first molded body, and more preferably 0.16 to 0.32 J / K for the second molded body. 0.4 to 1.2 J / K, more preferably 0.48 to 0.96 J / K.

In the present invention, the compressive strength (hereinafter also referred to as strength) of the cylindrical body layer 12 is usually 1 to 35 MPa. Moreover, if it is a 1st molded object, Preferably it is 1-10 MPa, More preferably, it is 3-5 MPa. If the compressive strength is less than 3 MPa, it may not be used in applications where a relatively strong load such as a pressure roller or a fixing roller is applied.
If it is a 2nd molded object, Preferably it is 10-35 Mpa, More preferably, it is 10-20 Mpa. If the compressive strength is less than 10 MPa, it may not be used in applications where a heavy load such as a shaft core, a tension roller, or a guide roller is applied. In order to obtain a strength exceeding 35 MPa, the bulk density becomes too high, and the expected heat insulating effect cannot be obtained, which is not preferable.

In the present invention, it is preferable to have both the above-described characteristics of thermal conductivity and strength. In general, in ceramic materials, thermal conductivity and compressive strength are contradictory properties. However, in the present invention, the cylindrical body layer 12 is made of ceramics mainly composed of calcium silicate, which will be described later. Thus, even if the bulk density is relatively low, both the low thermal conductivity and the high strength can be satisfied.
That is, in the first molded body, a thermal conductivity of 0.01 to 0.1 W / (m · K) and a compressive strength of 1 at a bulk density of 0.05 to 0.5 g / cm ³ by a manufacturing method described later. 10 MPa, furthermore, thermal conductivity of 0.06 to 0.09 W / (m · K) and compressive strength of 3 to 5 MPa can be realized. At a density of 0.5 to 1.5 g / cm ³ , the thermal conductivity is 0.1 to 0.5 W / (m · K), the compressive strength is 10 to 35 MPa, and the thermal conductivity is 0.15 to 0.35 W / (M · K) and a compressive strength of 10 to 20 MPa can be realized.

  The ceramic roller 10 of the present invention may be provided with a surface layer 13 that is covered with a cylindrical body layer 12 and contains a fluororesin. According to such a surface layer 13, the ceramic roller 10 can be given releasability. The thickness of the surface layer 13 is usually 5 to 500 μm, preferably 20 to 100 μm. If the thickness is less than 5 μm, there is a concern that the irregularities of the cylindrical body layer 12 may be raised on the surface or the surface layer 13 may be torn, and if it exceeds 500 μm, the material cost increases and this is economically disadvantageous. In addition to this, the heat insulation is also deteriorated.

  The fluororesin is not particularly limited as long as it is releasable with respect to the recording medium. However, PFA (perfluoroalkyl / vinyl ether copolymer resin), PTFE (polytetrachloroethylene resin), FEP (tetrafluoroethylene teite, Propylene fluoride copolymer resin) and the like. In particular, PFA is preferably used from the viewpoint of heat resistance and workability.

  Moreover, such a surface layer 13 may be comprised from inorganic materials, such as glass. The inorganic material is not particularly limited as long as it has heat resistance, and examples thereof include glass, alumina, silica, etc. Among them, glass is preferable from the viewpoints of heat resistance, workability, and surface smoothness.

  As shown in FIG. 3, the ceramic roller 10 of the present invention may include an intermediate layer 14 made of an elastic body between the cylindrical body layer 12 and the surface layer 13. According to such an intermediate layer 14, when the ceramic roller 10 is used as a pressure roller and pressed against the fixing roller, the intermediate layer 14 of the ceramic roller 10 is elastically deformed to be uniform with respect to the fixing roller. A predetermined nip width can be reliably formed in the recording medium conveying direction while being able to be pressed.

  The material used as the intermediate layer 14 is not particularly limited as long as it has flexibility. For example, silicone rubber, rubber such as fluoro rubber, sponge resin such as melamine resin, heat resistant felt made of aramid fiber, rock wool paper, Nonwoven fabrics such as glass fiber paper can be mentioned. In particular, fluororubber is suitable when heat resistance is required. The thickness of the intermediate layer 14 is usually 50 to 1000 μm, preferably 100 to 500 μm. If the thickness is less than 50 μm, the expected flexibility cannot be obtained, and if it exceeds 500 μm, the material cost is increased, which is economically disadvantageous and the heat insulation property is deteriorated.

A material having a high specific heat may be used as the intermediate layer 14. By using such a material, the intermediate layer 14 can store a small amount of heat, and when the ceramic roller 10 is used as a pressure roller, heat can be uniformly and reliably applied to the recording medium.
Examples of the material having a high specific heat include resins such as silicone rubber and fluororubber.

  Next, a ceramic roller according to a second embodiment of the present invention will be described below with reference to FIGS. This is merely an example and does not limit the present invention. FIG. 5 is an axial sectional view of a ceramic roller according to a second embodiment of the present invention, and FIG. 6 is an axial sectional view of a ceramic roller according to a second other embodiment of the present invention.

  In FIG. 5, a ceramic roller 20 is a roller used in a heat fixing device of an electrophotographic apparatus, and an axis 21 is made of ceramics whose main component is calcium silicate. The shape is not particularly limited as long as the surface has a columnar surface, and examples thereof include a columnar shape and a cylindrical shape, but a columnar shape is preferable from the viewpoint of strength and easy manufacture.

  The shaft core 21 may be formed from the first molded body or the second molded body described above. However, since the shaft core 21 can withstand use as the shaft core 21, the relatively high-density second molded body is better. It is preferable because higher strength can be obtained. Moreover, as FIG. 6 shows, the axial center part 22 may be formed by grinding the edge part 23 of a column-shaped molded object. Although not shown, such a ceramic roller is used not only as a shaft core of a fixing roller or a pressure roller, but also as a drive roller, a separation roller, a tension roller, and a guide roller as a single unit (axial core only). be able to.

  According to the second embodiment of the present invention, since the thermal conductivity and heat capacity of the shaft core are much lower than those of metal shaft cores that are conventionally used, the thermal energy taken through the shaft core is reduced. As a result, the power consumption of the fixing device can be greatly suppressed.

(Third embodiment)
Next, a ceramic roller according to a third embodiment of the present invention will be described below with reference to FIG. This is merely an example and does not limit the present invention. FIG. 7 is an axial sectional view of a ceramic roller according to the third embodiment of the invention.

  In FIG. 7, the ceramic roller 30 is formed with a cylindrical body layer 32 made of ceramics mainly composed of calcium silicate on the outer periphery of a shaft core 31 made of ceramics composed mainly of calcium silicate. Such a shaft core 31 may be formed from the first molded body or the second molded body described above. However, since the shaft core 31 can withstand use as the shaft core 31, the second molded body having a relatively high density is better. It is preferable because higher strength can be obtained. The cylindrical body layer 32 may also be formed from the first molded body or the second molded body described above, but the first molded body having a relatively low thermal conductivity is more preferable. It is preferable because high heat insulation can be obtained. Although not shown, such a ceramic roller can be used as, for example, a fixing roller, a pressure roller, a driving roller, a peeling roller, a tension roller, or a guide roller.

  The ceramic roller of 3rd Embodiment is a form which uses the ceramic roller of 2nd Embodiment as an axial center in the ceramic roller of 1st Embodiment. The ceramic roller of the third embodiment is the same as the ceramic roller of the first embodiment except that the shaft core is made of ceramics mainly composed of calcium silicate, and the surface layer 33 and intermediate layer (not shown) ) May be provided.

  According to the third embodiment of the present invention, it is possible to obtain a ceramic mainly composed of calcium silicate having a low thermal conductivity and high strength, which is excellent in heat insulation and heat resistance, and suitable for a high strength ceramic roller. Can get to. In addition, since the thermal conductivity and heat capacity of the shaft core are much lower than those of metal shaft cores used in the past, it is possible to reduce the heat energy taken through the shaft core, resulting in consumption of the fixing device. Electric power can be greatly suppressed.

As a method of manufacturing the ceramic roller of the first embodiment,
A1) A step of obtaining calcium silicate crystals by heating a siliceous raw material and a calcareous raw material together with a large amount of water while stirring in an autoclave to a high temperature;
B1) forming a calcium silicate crystal-containing shaped body from the slurry containing the calcium silicate crystals;
D1) forming a cylindrical body layer made of the calcium silicate crystal-containing molded body on the outer periphery of the shaft core (first manufacturing method of the first embodiment). Here, the method including the step A1) and the step B1) corresponds to the above-described method for producing the first molded body.

  In step A1), the types of calcium silicate crystals (zonotolite crystals, tobermorite crystals, amorphous C—S—H crystals) generated by appropriately setting the temperature conditions, pressure conditions, and stirring conditions in the autoclave are specified. However, it is preferable to produce only zonotlite crystals under the conditions described later. The primary particles of the zonotlite crystals form needle-like crystals, and the primary particles form spherical secondary particles 15 having a diameter of 10 to 150 μm as shown in FIGS. 4a and 4b. Further, the primary particles are aggregated and further combined to form spherical secondary particles 15 having a hollow shape or a state close to the inside, and needle-like zonotlite crystals are chestnut-like on the surface of the secondary particles 15. It precipitates in. The secondary particles 15 made of such zonotlite crystals are firmly bonded to each other by drying to remove water and exhibit strength. Moreover, since the inside of the secondary particle 15 is a cavity or a state close thereto as described above, the obtained molded body is lightweight and has a low thermal conductivity. Therefore, a molded body having a low heat capacity, low thermal conductivity, and excellent strength can be obtained. 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. However, it is necessary to carry out hydrothermal synthesis in an autoclave at a saturated vapor pressure of 7 to 20 kg / cm ² , preferably 13 to 17 kg / cm ² . In addition, it is necessary to adjust the siliceous raw material and the calcareous raw material to a CaO / SiO ₂ molar ratio of usually 0.8 to 1.2, preferably 0.9 to 1.1.

The siliceous raw material is not particularly limited as long as SiO ₂ is contained as a component, and examples thereof include silica and fused silica. However, in order to form a zonotlite crystal, a crystalline material, particularly silica is used. It is preferable to use it. Further, it is preferable to use fine powder having an average particle diameter of 5 to 15 μm.
The calcareous raw material is not particularly limited as long as it contains CaO as a component, and examples thereof include slaked lime and quicklime, but quicklime is preferably used from the viewpoint of the growth of zonotlite crystals.

  In step B1), the slurry may further contain a reinforcing material in addition to the calcium silicate crystals. By adding such a reinforcing material (hereinafter also referred to as blending), a calcium silicate crystal-containing molded body having higher strength can be obtained. Examples of such reinforcing materials include hydraulic binders such as alumina cement and Portland cement, and inorganic binders such as colloidal silica and alumina sol. The addition amount (hereinafter also referred to as blending amount) is 0 to 20 parts by mass, preferably 10 to 20 parts by mass with respect to 100 parts by mass of the calcium silicate crystals.

  The slurry may further contain a filler in addition to the calcium silicate crystals. By adding such a filler, cost reduction of raw materials and improvement of moldability can be expected. Such fillers include talc, diatomaceous earth and fly ash. The addition amount is 0-20 mass parts with respect to 100 mass parts of calcium silicate crystals, preferably 5-10 mass parts.

  The slurry may further contain a reinforcing fiber in addition to the calcium silicate crystals. By adding such reinforcing fibers, a molded body having higher strength can be obtained. Examples of such reinforcing fibers include glass fibers, ceramic fibers, alumina fibers, wollastonite, pulp, polypropylene fibers, aramid fibers, and carbon fibers. The addition amount is 0-20 mass parts with respect to 100 mass parts of calcium silicate crystals, preferably 5-10 mass parts.

  The slurry may further contain a lightweight aggregate in addition to the calcium silicate crystals. By adding such a lightweight aggregate, the bulk density can be further lowered while maintaining the strength. Examples of such lightweight aggregates include microsilica, perlite, shirasu balloon, and glass balloon. The addition amount is 0-20 mass parts with respect to 100 mass parts of calcium silicate crystals, preferably 5-10 mass parts.

  In addition to calcium silicate crystals, the slurry may contain a flocculant and a thickener (also referred to as an extrusion molding aid) as necessary.

In step B1), the molding method is not particularly limited as long as it is a known technique, and examples thereof include a dewatering molding method such as a papermaking method and a dewatering press molding method, and an extrusion molding method. In the case of cm ³ or less, a dehydration press molding method in which molding is performed from a slurry state having a large amount of water is suitable. According to the dehydration 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 first 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. .
The density of the compact is adjusted by changing the bulk of the zonotlite crystal secondary particles in the slurry and the molding pressure during 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 changing the starting material, slurry concentration, stirring conditions, and the like. The molding pressure is usually 1 to 70 kgf / cm ² , preferably 10 to 50 kgf / cm ² , and the time is usually 1 to 30 minutes, preferably 5 to 10 minutes.

If the slurry is concentrated and a molding aid is added to form a kneaded product containing 50 to 100 parts by mass of water with respect to 100 parts by mass of the solid content, a molded article containing calcium silicate crystals is formed by an extrusion molding method. You can also The extrusion molding method can be suitably used when the density of the molded product to be obtained is 0.5 g / cm ³ or more.
Here, there is no restriction | limiting in particular if a shaping | molding adjuvant is an organic binder which can be used as an extrusion shaping | molding adjuvant, The compounding quantity should just be 3-10 mass parts with respect to 100 mass parts of solid content.
Further, the kneaded product may contain other optional components, and the blending amount thereof is 0 to 20 parts by mass, preferably 10 to 20 parts by mass with respect to 100 parts by mass of the mixed calcium silicate crystals. Parts by weight, filler 0-50 parts by weight, preferably 10-30 parts by weight, reinforcing fibers 0-20 parts by weight, preferably 5-10 parts by weight, lightweight aggregate 0-40 parts by weight, preferably 10-20 parts by weight. Part.
The density may be adjusted by combining the amount of kneaded water, filler, and lightweight aggregate. Examples of the kneading apparatus used in the kneading process include a pressure kneader, a double-arm kneader, a high-speed mixer, a butterfly mixer, and the like, and any known one can be used as appropriate.

  The calcium silicate crystal-containing molded body obtained by the above-described method is dried by a known technique to obtain a first molded body. The drying conditions are usually 100 to 200 ° C. and about 1 to 24 hours, but if a dehydration molding method is used, it is usually 50 to 300 ° C. for 1 to 24 hours, preferably 150 to 250 ° C. for 3 to 10 hours. It is preferable to apply.

  The shape of the calcium silicate crystal-containing molded body is not particularly limited, and examples thereof include a board shape, a prismatic shape, a cylindrical shape, a semicylindrical shape, a cylindrical shape or a semicylindrical shape. In order to obtain such a shape, a mold having a desired shape may be used in the case of dehydration molding. For example, a cylindrical mold 40 as shown in FIG. 8 or a mold as shown in FIG. A semi-cylindrical mold 45 may be used. For example, the cylindrical molding die 40 includes a pair of half dies 41. A half-circular groove 42 is formed in the half mold 41, and a cylindrical hollow portion 44 is formed by closely contacting the bonding surface 43 with the grooves 42 facing each other. A cylindrical shaped body can be obtained by placing a cylinder 45 having a mesh structure on the surface for suction dehydration in the center of the hollow portion 44, injecting slurry into the hollow portion and removing moisture through the cylinder 45. it can.

  In the step D1), there is no particular limitation on the method for forming the cylindrical body layer made of the calcium silicate crystal-containing molded body on the outer periphery of the shaft core. For example, in the hollow part formed in the cylindrical molded body, A shaft core that has been previously coated with an adhesive may be inserted, or an adhesive may be applied to the inner surface formed inside the semi-cylindrical molded body, so that the pair of semi-cylindrical molded bodies are pivoted. It may be fixed on the core. The adhesive is not particularly limited and a known one can be used, but a silicone rubber adhesive having heat resistance is preferable.

Step D1) may further include a step of cutting out a molded body piece having a desired shape from the calcium silicate crystal-containing molded body and a step of fixing the calcium silicate crystal-containing molded body piece to the shaft core. The formed body piece may be cylindrical, or may be a semi-cylindrical shape or a part obtained by dividing the semi-cylindrical shape. For example, as shown in FIG. 10, a cylindrical molded body piece 52 may be punched out from a board-shaped molded body 51 obtained by the method described above, or a semi-cylindrical shape as shown in FIG. The molded piece 53 may be cut out. As a method for cutting out a molded body piece of a desired shape from the molded body, for example, known methods such as cutting, laser processing, polishing, and combinations thereof can be used. The molded piece thus obtained may be fixed to the shaft core by the method described above. In the case of a cylindrical shaped piece, a plurality of shaped pieces may be connected and fixed to the shaft core.
Moreover, you may grind the molded object piece fixed to the axial center, and form a cylindrical body layer. For example, as shown in FIG. 12, a prismatic molded body piece 56 is cut out from a board-shaped molded body 55, and the axial center is the same as the central portion along the length direction of the cut out prismatic molded body piece 56. A through-hole 57 having a diameter is formed, and after inserting a shaft core 58 previously coated with an adhesive into the through-hole 57 and confirming that the molded body piece 56 is fixed to the shaft core, the molded body The cylindrical layer 59 may be formed by grinding the outer diameter of the piece 56.
The surface of the cylindrical body layer 59 is preferably cut or polished in order to eliminate unevenness and make a perfect circle.

  Step B1) and step D1) may be performed in the same step. In the dehydration press molding method, the shaft core is set in advance in the mold, and the shaft core is integrally formed with the slurry. In the extrusion molding method, the calcium silicate crystal-containing molded body is formed along the cylindrical surface of the shaft core. Extrusion molding may be performed. Such a method is preferable because the processing step of the molded body can be omitted.

As another method of manufacturing the ceramic roller of the first embodiment,
A2) A step of obtaining a calcium silicate crystal precursor by heating a siliceous raw material and a calcareous raw material together with a large amount of water while stirring in an autoclave to a high temperature;
B2) forming a calcium silicate crystal precursor-containing molded body from a slurry containing the calcium silicate crystal precursor;
C2) heating the calcium silicate crystal precursor-containing molded body to a high temperature in an autoclave to produce calcium silicate crystals to obtain a calcium silicate crystal-containing molded body;
D2) A method comprising a step of forming the calcium silicate crystal precursor-containing molded body or a cylindrical body layer made of the calcium silicate crystal-containing molded body on the outer periphery of the shaft core (second manufacturing method of the first embodiment) Is mentioned. Here, the method including the steps A2), B2), and C2) corresponds to the above-described method for producing the third molded body. Although the 2nd manufacturing method of the 1st form is explained below, only a different portion from the 1st manufacturing method of the 1st form is explained.

  In step A2), the calcium silicate crystal precursor is slightly reacted with the siliceous raw material and the calcareous raw material, but is not completely reacted, that is, a state before becoming calcium silicate crystals. Means things.

In step A2), the difference from step A1) is that what is produced is not a calcium silicate crystal but a calcium silicate crystal precursor, and as in step A1), the temperature conditions, pressure conditions, and stirring conditions in the autoclave are the same. The type of calcium silicate crystal precursor (zonotolite crystal precursor, tobermorite crystal precursor, amorphous C—S—H crystal precursor) produced by appropriately setting the silicate can be specified. It is preferable to produce only the body.
The zonotlite crystal precursor also forms hollow spherical secondary particles having a diameter of 10 to 150 μm, like the zonotlite crystal. Therefore, the obtained molded body also exhibits the same effect as the molded body obtained from zonotlite crystals. The presence or absence of such a crystal precursor can be confirmed by SEM or an optical microscope.

In step A2), the raw materials necessary for obtaining a suitable zonotlite crystal precursor as a calcium silicate precursor, conditions for hydrothermal synthesis, etc. are the same as in step A1), but the silicic acid raw material and the calcareous raw material are combined. It is necessary to adjust CaO / SiO ₂ to 1.1 to 1.3 with a relatively large CaO component in a molar ratio.

In step B2), the difference from step B1) is that what is contained in the slurry is not a calcium silicate crystal but a calcium silicate crystal precursor, and the resulting molded body is not a calcium silicate crystal-containing molded body, Calcium silicate crystal precursor-containing molded body. Other optional additives in slurry and blending, molding method, drying conditions, and shape of molded body are the same, but zonotlite crystals are produced by hydrothermal synthesis described later. Therefore, it is necessary to add a silicic acid raw material and adjust CaO / SiO ₂ to a molar ratio of 0.9 to 1.1.

In step C2), the pressure is usually 7 to 20 kg / cm ² , preferably 8 to 12 kg / cm 2, and the time is usually 1 to 24 hours, preferably 6 to 10 hours. Note that step C2) may be performed after being fixed to the shaft core, or may be performed before being fixed to the shaft core.

  In step D2), the difference from step D1) is that the molded body formed on the outer periphery of the shaft core is not a calcium silicate crystal-containing molded body, but a calcium silicate crystal precursor-containing molded body or a calcium silicate crystal-containing body. In other respects, the method for forming the cylindrical layer is as described in paragraphs [0056] to [0058].

As another method of manufacturing the ceramic roller of the first embodiment,
A3) obtaining a kneaded material containing a siliceous raw material, a calcareous raw material, a molding aid, and water;
B3) a step of extruding an amorphous-containing molded body from the kneaded product;
C3) heating the amorphous-containing shaped body to a high temperature in an autoclave to produce calcium silicate crystals to obtain a calcium silicate crystal-containing shaped body;
D3) A method (third manufacturing method of the first embodiment) including a step of forming a cylindrical body layer made of the amorphous-containing molded body or the calcium silicate crystal-containing molded body on the outer periphery of the shaft core. Here, the method including the step A3), the step B3), and the step C3) corresponds to the method for manufacturing the second molded body described above. Although the 3rd manufacturing method of the 1st form is explained below, only a different portion from the 1st manufacturing method and the 2nd manufacturing method of the 1st form is explained.

  In step A3), the unreacted crystal is a crystal of a siliceous raw material or a calcareous raw material that is a raw material of zonotlite crystal or tobermorite crystal, amorphous C—S—H crystal produced by heating to high temperature in an autoclave. I mean. The presence or absence of such unreacted crystals can be easily determined by X-ray diffraction of the composition because a specific diffraction peak can be obtained by X-ray diffraction.

The siliceous raw material is not particularly limited as long as SiO ₂ is contained as a component, and examples thereof include silica and fused silica. In order to produce a suitable calcium silicate crystal, a crystalline material is used. In particular, it is preferable to use silica stone. Further, it is preferable to use fine powder having an average particle diameter of 5 to 15 μm.
The calcareous material is not particularly limited as long as it contains CaO as a component, and examples thereof include slaked lime and quicklime, but slaked lime is preferably used from the viewpoint of productivity.
It is necessary to adjust the siliceous raw material and the calcareous raw material to a CaO / SiO ₂ molar ratio of usually 0.7 to 1.2, preferably 0.8 to 1.0. Here, the molding aid is not particularly limited as long as it is an organic binder that can be used as an extrusion molding aid, and examples thereof include methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylic resin, and kibushi clay. A combination of the above can also be used. Moreover, the compounding quantity should just be 3-10 mass parts with respect to 100 mass parts of solid content.

  In step A3), the kneaded material may further contain a reinforcing material in addition to the siliceous material, the calcareous material, the molding aid, and water. By adding such a reinforcing material (hereinafter also referred to as blending), it is possible to obtain a molded body having higher strength. Examples of such reinforcing materials include hydraulic binders such as alumina cement and Portland cement, and inorganic binders such as colloidal silica and alumina sol. The addition amount (hereinafter also referred to as blending amount) is 0 to 20 parts by mass, preferably 10 to 20 parts by mass with respect to 100 parts by mass in total of the siliceous material and the calcareous material.

  The kneaded material may further contain a filler in addition to the siliceous raw material, the calcareous raw material, the molding aid and water. By adding such a filler, cost reduction of raw materials and improvement of moldability can be expected. Such fillers include talc, diatomaceous earth and fly ash. The addition amount is 0 to 100 parts by mass, preferably 10 to 50 parts by mass with respect to 100 parts by mass in total of the siliceous material and the calcareous material.

  The kneaded material may further contain a reinforcing fiber in addition to the siliceous raw material, the calcareous raw material, the molding aid and water. By adding such reinforcing fibers, a molded body having higher strength can be obtained. Examples of such reinforcing fibers include glass fibers, ceramic fibers, alumina fibers, wollastonite, pulp, polypropylene fibers, aramid fibers, and carbon fibers. The addition amount is 0 to 100 parts by mass, preferably 5 to 30 parts by mass with respect to 100 parts by mass in total of the siliceous material and the calcareous material.

  The kneaded material may further contain a lightweight aggregate in addition to the siliceous raw material, the calcareous raw material, the molding aid, and water. By adding such a lightweight aggregate, the bulk density can be further lowered while maintaining the strength. Examples of such lightweight aggregates include microsilica, perlite, shirasu balloon, and glass balloon. The addition amount is 0 to 100 parts by mass, preferably 10 to 50 parts by mass with respect to 100 parts by mass in total of the siliceous material and the calcareous material.

In step C3), the pressure is usually 7 to 20 kg / cm ² , preferably 10 to 15 kg / cm ² , and the time is usually 1 to 24 hours, preferably 6 to 10 hours.

  The calcium silicate crystal-containing molded body obtained by the above-described method is dried by a known technique to obtain a second molded body. Drying conditions are preferably 100 to 200 ° C. and 5 to 12 hours.

According to the manufacturing method of the 2nd molded object, even if comparatively high density, such as bulk density 0.5-1.5 g / cm < ³ >, thermal conductivity 0.1-0.5 W / (m * K) and A second molded body having a compressive strength of 10 to 35 MPa, a thermal conductivity of 0.15 to 0.35 W / (m · K), and a compressive strength of 10 to 20 MPa can be obtained.

In step D3), the difference from step D1) is that the molded body formed on the outer periphery of the shaft core is not a calcium silicate crystal-containing molded body but an amorphous-containing molded body or a calcium silicate crystal-containing molded body. In addition, the method for forming the cylindrical layer is as described in the paragraphs [0056] to [0058].
According to the step B3) and the step D3) being the same step, that is, the step of extruding the unreacted crystal-containing formed body from the kneaded product along the cylindrical surface of the shaft core, the processing step of the formed body is omitted. This is preferable.
Here, step D3) may be performed after step C3) or may be performed before.

  As a method of forming the above-mentioned surface layer on the surface of the cylindrical body layer, a ceramic roller is inserted into a heat-shrinkable fluororesin tube and then heated to shrink the tube so that the surface of the roller is covered with the surface layer. And a method in which a coating liquid containing a fluororesin is applied to the surface of the roller and then dried by heating to form a surface layer. Examples of methods that can be used for such coating include brush coating, dip coating, spray coating, roll coating, bar coating, and spin coating. When the roll is irregular or small in size, a method such as brushing by hand is practical.

  Further, when the surface layer is a glass layer, a method of forming a surface layer by applying a coating liquid containing glass frit to the surface of the roller and then baking by heating is exemplified. Examples of methods that can be used for such coating include spray coating, electrostatic powder coating, and doctor coating.

  As a method of forming the intermediate layer described above between the cylindrical body layer and the surface layer, an axial core and a cylindrical body layer are set inside the mold, and a fluorine tube is set outside, and liquid silicon rubber is poured into the gap. A method of curing silicone rubber, a method of coating and adhering a silicone rubber tube to a cylindrical body layer, a method of spraying liquid silicone rubber on a cylindrical body layer, a method of applying liquid silicone rubber to the surface of a cylindrical body layer by roll coating Is mentioned.

The method for producing the ceramic roller of the second embodiment includes a step of obtaining a molded body by the above-described method for producing the first molded body, the method for producing the second molded body, or the method for producing the third molded body, And a method including a step of obtaining a columnar or cylindrical shaft core from the body (hereinafter also referred to as a first production method of the second form).
In addition, a method including a step of obtaining a columnar or cylindrical shaft core by the above-described method for manufacturing the first molded body, the method for manufacturing the second molded body, or the method for manufacturing the third molded body (hereinafter referred to as the second mode of the second embodiment). 2).
Furthermore, you may provide the process of grinding the edge part of the said column-shaped molded object and forming an axial center part.

  As a method of manufacturing the ceramic roller of the third embodiment, the manufacturing method of the first molded body described above on the outer periphery of the shaft core obtained by the first manufacturing method or the second manufacturing method of the second embodiment described above, Examples thereof include a method including a step of forming a cylindrical body layer made of a molded body obtained by the method for manufacturing the second molded body or the method for manufacturing the third molded body.

  Hereinafter, the present invention will be described by way of specific examples, but the present invention is not limited to these examples. First, the ceramic roller according to the first embodiment will be described below by taking a pressure roller as an example.

Example 1
Formation of zonotlite crystals:
Quicklime as a calcareous raw material (Adachi quicklime (150 mesh)) is poured into 24 times the amount of hot water (temperature 90 ° C) and digested for 30 minutes while stirring with a stirrer having a stirring blade rotating at 160 rpm. Obtained. 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 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 a large number of needle-like crystals gathered to form spherical secondary particles having a diameter of 30 to 130 μm.

Slurry adjustment:
7 parts by weight of Portland cement (ordinary Portland cement manufactured by Ube Mitsubishi Cement Co., Ltd.), 5 parts by weight of glass fiber (ECS131-33G manufactured by Nippon Electric Glass Co., Ltd.), solid content conversion with respect to 100 parts by weight of xonotlite crystals 100 ppm of a flocculant (Sanfloc N-0P manufactured by Sanyo Chemical Industries, Ltd.) was added and mixed to obtain a slurry for dehydration press molding. The slurry was poured into a mold and subjected to dehydration press molding at a molding pressure of 5 kgf / cm ² and then dried at 100 ° C. for 12 hours to obtain a board-like molded body having a length of 350 mm, a width of 350 mm, and a thickness of 50 mm. The molded body had a bulk density of 0.11 g / cm ³ .

Roller manufacturing:
From the obtained board-like molded body, a prismatic molded body piece having a length of 50 mm, a width of 50 mm, and a length of 330 mm was cut out. A through hole having a diameter of 30 mm was formed at the center along the length direction of the molded body piece. A stainless steel shaft core in which a silicone rubber adhesive (KE45 manufactured by Shin-Etsu Chemical Co., Ltd.) was previously applied was inserted into the through hole. After confirming that the molded body piece was fixed to the shaft core, the outer diameter of the molded body piece was ground to obtain a cylindrical body layer having a thickness of 5 mm.

Surface layer formation:
A thermosetting silicone rubber adhesive (KE1833 made by Shin-Etsu Chemical Co., Ltd.) was applied to the outer peripheral surface of the cylindrical body layer with a roll coater, and a PFA heat shrinkable tube (JFA Co., Ltd. Junflon inner surface treated PFA heat shrinkable tube). And a PFA heat shrinkable tube was heat-shrinked to form a surface layer having a thickness of 30 μm.

(Example 2)
A pressure roller was obtained in the same manner as in Example 1 except that the molding pressure at the time of dehydration press molding was changed to 15 kgf / cm ² and the bulk density of the molded body was 0.25 g / cm ³ .

(Example 3)
A pressure roller was obtained in the same manner as in Example 1, except that the molding pressure at the time of dehydration press molding was changed to 30 kgf / cm ² and the bulk density of the molded body was 0.39 g / cm ³ .

(Comparative Example 1)
In Example 1, a pressure roller having the same shape and structure was obtained using a silicone rubber sponge having a bulk density of 0.6 g / cm ³ instead of the cylindrical body layer made of ceramics mainly composed of calcium silicate. .

(Comparative Example 2)
In Example 1, a pressure roller having the same shape and structure was obtained by using silicone rubber having a bulk density of 1.0 g / cm ³ instead of the cylindrical body layer made of ceramics mainly composed of calcium silicate.

  Next, the ceramic roller of the second embodiment will be described below by taking a drive roller as an example. The drive roller is composed only of the shaft core.

Example 4
Dry mix:
Perlite (Showa Chemical Co.) (Company Topco 1BS) 30 parts by mass and 10 parts by mass of methylcellulose (Yuken Kogyo Co., Ltd. Serander YB152A) as a molding aid were dry-mixed for 10 minutes with a double-arm kneader to obtain a mixture. The amount of slaked lime and silica powder is adjusted to CaO / SiO ₂ is 0.9 in molar ratio.

Wet kneading:
Water was added to a total of 100 parts by mass of slaked lime and silica powder to the double-arm kneader containing the mixture, and kneaded in a wet process for 20 minutes to obtain a kneaded product. Water was adjusted so as to be included in an amount of 80 parts by mass with respect to 100 parts by mass of the solid content of the kneaded product.

Extrusion molding:
From the kneaded product, a cylindrical amorphous-containing molded body having a diameter of 22 mm and a length of 350 mm was extruded using a vacuum kneading extrusion molding machine.

Hydrothermal synthesis reaction:
The amorphous-containing molded body was subjected to a hydrothermal synthesis reaction in an autoclave at a pressure of 7 kg / cm ² for 4 hours to obtain a molded body. It was confirmed that the main component of the obtained molded body was composed of tobermorite crystals and existed throughout the molded body.

Dry:
After the molded body was dried at room temperature, the surface was polished to obtain a shaft core having a diameter of 20 mm and a bulk density of 0.8 g / cm ³ , that is, a driving roller.

(Example 5)
A drive roller was obtained in the same manner as in Example 4 except that dry mixing and wet kneading were changed as follows, and the bulk density of the compact was 1.2 g / cm ³ .

Dry mix:
For a total of 100 parts by mass of slaked lime as a calcareous material (Okutama Kogyo Co., Ltd. special name) and siliceous powder as a siliceous material (3500 Blaine, Chichibu Mining Co., Ltd.) Company Serander YB152A) 8 parts by mass was dry-mixed with a double arm type kneader for 10 minutes to obtain a mixture. The amount of slaked lime and silica powder is adjusted to CaO / SiO ₂ is 0.9 in molar ratio.

Wet kneading:
Water was added to a total of 100 parts by mass of slaked lime and silica powder to the double-arm kneader containing the mixture, and kneaded in a wet process for 20 minutes to obtain a kneaded product. Water was adjusted so that 40 mass parts was contained with respect to 100 mass parts of solid content of kneaded material.

(Comparative Example 3)
In Example 4, a drive roller having the same shape was obtained using aluminum having a bulk density of 2.7 g / cm ³ instead of the shaft core made of ceramics mainly composed of calcium silicate.

(Comparative Example 4)
In Example 4, a drive roller having the same shape was obtained using stainless steel having a bulk density of 7.4 g / cm ³ instead of the shaft core made of ceramics mainly composed of calcium silicate.

(Test method)
In Examples 1 to 3 and Comparative Examples 1 and 2, in Table 1, each of the evaluation items described in Table 2 in Examples 4, 5 and Comparative Examples 3 and 4 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) Thermal conductivity (W / (m · K)): A flat plate-shaped test piece having a width of 100 mm, a thickness of 20 mm, and a length of 50 mm was separately prepared as the test piece with the same raw material composition as the cylindrical body layer. According to JIS R2616 “Unsteady hot wire method”, the thermal conductivity at room temperature of the surface of the test specimen was measured with a rapid thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Industry Co., Ltd.
(3) Heat capacity (J / K): The specimen was pulverized, 50 g of the specimen was measured for specific heat using a high temperature sample dropping type specific heat measuring device, and the heat capacity per 1 cm ³ was calculated from the above bulk density value. did.
(4) Compressive strength (MPa): A test piece having the same raw material composition as that of the cylindrical layer and having a side of 60 mm is separately prepared as a test piece, in accordance with JIS R1608 “Testing method for compressive strength of fine ceramics”. The measurement was performed.
(5) Heat-resistant dimensional change: A rectangular parallelepiped test piece whose dimensions were measured in advance was put into a 250 ° C. constant temperature machine, and the dimensional change after one week was confirmed. The case where there was no dimensional change was marked with ◯, the case where some deformation occurred, Δ, and the case where the size changed significantly, X.
(6) Temperature increase rate (seconds): a heat fixing roller in which a halogen lamp is embedded in an aluminum pipe having an outer diameter of 40 mm, a length of 330 mm, and a thickness of 1 mm, and a pressure roller having an outer diameter of 40 mm and a length of 330 mm In the heat fixing device as the main configuration, the pressure roller is replaced with a pressure roller to be evaluated, and the pressure roller is rotated with the pressure roller being in pressure contact with the heat fixing roller with a total load of 10 kgf. After adjusting the temperature to room temperature, the time until the temperature of the heat fixing roller was raised to 180 ° C. by supplying 1000 W of power without passing through the printing paper was measured.
(7) Power consumption (W): The average power consumption was determined for 30 to 60 seconds from the start of temperature increase of the heat fixing roller under the same conditions as the measurement of the temperature increase rate.
(8) Durability: After the evaluations in (6) and (7) above, after the heat fixing roller was continuously rotated for 100 hours while applying a load without passing the paper at a temperature controlled at 180 ° C. The outer diameter and length of the pressure roller were measured, and the state of deformation was confirmed. A case where no deformation was observed was indicated by ◯, a case where slight deformation was observed was indicated by Δ, and a case where remarkable deformation was observed was indicated by ×. Two types of loads, 10 kgf and 30 kgf, were applied.
(9) Three-point bending strength (MPa): Using a cylindrical specimen having a diameter of 22 mm and a length of 350 mm with the same raw material composition as that of the cylindrical body layer, according to JIS R1608 “Testing method for compressive strength of fine ceramics” And measured.

  From the results shown in Table 1, the pressure rollers of Examples 1 to 3 have lower thermal conductivity, moderate compressive strength, and better heat resistance, heating rate, and durability than Comparative Examples 1 and 2. It was excellent. Also, good results were obtained with the same or lower power consumption.

  From the results in Table 2, since the drive rollers of Examples 4 and 5 have a very low thermal conductivity and a very high heat insulating property compared to Comparative Examples 3 and 4, the power consumption is reduced and the heating rate is increased. Shortening is expected. Further, since the strength that can withstand use as a drive roller is generally 10 MPa or more as a three-point bending strength, it was confirmed that the drive rollers of Examples 4 and 5 can withstand use.

It is sectional drawing of the radial direction of the ceramic roller which is the 1st Embodiment of this invention. It is sectional drawing of the axial direction of the ceramic roller which is the 1st Embodiment of this invention. It is sectional drawing of the radial direction of the ceramic roller which is 1st other embodiment of this invention. It is a SEM photograph (a: 200 times) of a secondary particle in the zonotlite crystal concerning the present invention. It is a SEM photograph (b: 1000 times) of a secondary particle in the zonotlite crystal concerning the present invention. It is sectional drawing of the axial direction of the ceramic roller which is the 2nd Embodiment of this invention. It is sectional drawing of the axial direction of the ceramic roller which is 2nd other embodiment of this invention. It is sectional drawing of the axial direction of the ceramic roller which is the 3rd Embodiment of this invention. It is explanatory drawing which shows the shaping | molding method of the molded object used when manufacturing the ceramic roller of this invention. It is explanatory drawing which shows the other shaping | molding method of the molded object used when manufacturing the ceramic roller of this invention. It is explanatory drawing which shows the method of cutting out the molded object piece used when manufacturing the ceramic roller of this invention from a board-shaped molded object. It is explanatory drawing which shows the other method of cutting out the molded object piece used when manufacturing the ceramic roller of this invention from a board-shaped molded object. It is explanatory drawing which shows one example of the manufacturing method of the ceramic roller of this invention.

Explanation of symbols

10, 20, 30 Ceramic roller 11, 21, 31, 58 Shaft core 12, 32, 59 Cylindrical layer 13, 33 Surface layer 14 Intermediate layer 15 Secondary particles of zonotlite crystal 22 Shaft core 23 End 40, 46 Molding Mold 41 Semicircular mold 42 Groove 43 Joint surface 44 Hollow part 45 Cylinder 51, 55 Molded body 52, 53, 56 Molded body piece 57 Through hole

Claims (13)

In a roller comprising a shaft core and a cylindrical body layer formed on the outer periphery of the shaft core,
The cylindrical body layer is formed of a ceramic molded body mainly composed of calcium silicate, which is obtained by molding and drying a calcium silicate crystal previously obtained by hydrothermal synthesis.
The main component of the calcium silicate is zonotolite crystals,
Primary particles of the xonotlite crystal forms needle-like crystals, the primary particles form secondary particles of spherical diameters 10 to 150 m,
The thermal conductivity of the cylindrical layer is 0.01 to 0.1 W / (m · K).
Ceramic roller characterized by that. 2. The ceramic roller according to claim 1, wherein the cylindrical layer has a bulk density of 0.05 to 0.5 g / cm < ³ >. 3. The ceramic roller according to claim 1, wherein the cylindrical layer has a thermal conductivity of 0.06 to 0.09 W / (m · K). 4. The ceramic roller according to any one of claims 1 to 3, further comprising a surface layer coated with the cylindrical body layer and containing a fluororesin. 5. The ceramic roller according to claim 4, further comprising an intermediate layer made of an elastic body between the cylindrical layer and the surface layer. The ceramic roller according to any one of claims 1 to 5, wherein the ceramic roller is used in a heat fixing device of an electrophotographic apparatus. The ceramic roller according to any one of claims 1 to 6, wherein the amount of the cylindrical body layer is 10 to 20 parts by mass of a reinforcing material and 5 to 10 fillers with respect to 100 parts by mass of calcium silicate. A ceramic roller characterized by comprising 5 parts by mass, 5-10 parts by mass of reinforcing fibers, and 5-10 parts by mass of lightweight aggregate. The ceramic roller according to any one of claims 1 to 7, wherein the cylindrical body layer has a bulk density of 0.2 to 0.4 g / cm ³ . A ceramic roller characterized in that, in a roller used in a heat fixing device of an electrophotographic apparatus, the shaft core is made of ceramics mainly composed of calcium silicate. 10. The ceramic roller according to claim 9, wherein a cylindrical body layer made of ceramics mainly composed of calcium silicate is further formed on an outer periphery of the shaft core. A1) obtaining calcium silicate crystals by heating a siliceous raw material and a calcareous raw material together with a large amount of water to a high temperature in an autoclave;
Here, the calcium silicate crystal is a zonotlite crystal, the primary particles of the zonotrite crystal form needle-like crystals, and the primary particles form spherical secondary particles having a diameter of 10 to 150 μm,
B1) forming a calcium silicate crystal-containing shaped body from the slurry containing the calcium silicate crystals;
And D1) forming a cylindrical body layer made of the calcium silicate crystal-containing molded body on the outer periphery of the shaft core. A2) a step of obtaining a calcium silicate crystal precursor by heating a siliceous raw material and a calcareous raw material together with a large amount of water in an autoclave to a high temperature;
B2) forming a calcium silicate crystal precursor-containing molded body from a slurry containing the calcium silicate crystal precursor;
C2) heating the calcium silicate crystal precursor-containing molded body to a high temperature in an autoclave to produce calcium silicate crystals to obtain a calcium silicate crystal-containing molded body;
And D2) forming a cylindrical body layer formed of the calcium silicate crystal precursor-containing molded body or the calcium silicate crystal-containing molded body on the outer periphery of the shaft core. A3) obtaining a kneaded material containing a siliceous raw material, a calcareous raw material, a molding aid, and water;
B3) a step of extruding an amorphous-containing molded body from the kneaded product;
C3) heating the amorphous-containing shaped body to a high temperature in an autoclave to produce calcium silicate crystals to obtain a calcium silicate crystal-containing shaped body;
D3) forming a cylindrical body layer made of the amorphous-containing molded body or the calcium silicate crystal-containing molded body on the outer periphery of the shaft core, and a method for producing a ceramic roller.