Ceramic roller and method for manufacturing the same

The present invention relates to a ceramic roller provided with a shaft core and a cylindrical layer formed on the outer peripheral side of the shaft core, and a method for manufacturing the same, and is particularly mounted on an electrophotographic apparatus such as an electrocopier or a printer that uses a charged image. The present invention relates to a ceramic roller used in a heat fixing device and a method for manufacturing the same.

When an electrophotographic device such as an electrostatic copier or a laser printer projects an optical image on the surface of a photoconductor uniformly charged in the dark, an electrostatic latent image corresponding to the optical image is formed on the surface of the photoconductor, and the surface thereof is formed. An image is developed by spraying a charged toner, which is a developer, on the surface of the photoconductor and electrostatically adhering the toner to the surface of the photoconductor. The image is copied by transferring to a paper surface, 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.

The heat fixing device portion that heat-fixes the toner on the paper surface by 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 transfer roller. It is known that the roller is composed of the above three rollers and has an endless belt wound between one of the heat fixing roller and the pressure roller and the transport roller. That is, the printing paper is supported from the back surface side by a pressure roller or a pressure roller via an endless belt, and is pressurized and heated by a heat fixing roller heated from the front surface side to fuse the toner on the paper surface. Is heat-fixed. The temperature of the heat-fixing roller is generally about 150 to 200 ° C. However, when the temperature of the roller is raised, it may temporarily reach a higher temperature 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 at which it can be fused, but when the heat fixing operation is performed, the printing paper or pressure roller, which is always much lower than the heat fixing temperature, Alternatively, since it comes into contact with the endless belt and rotates, a large amount of heat energy is taken away and cooled at that moment. Therefore, the heat fixing roller needs to be heated to a higher temperature in anticipation of cooling due to such contact, and the power consumption increases. Therefore, the pressure roller is required to have a small thermal conductivity, that is, a heat insulating property. Further, since the pressure roller comes into contact with the high temperature heat fixing roller, heat resistance and strength are also required. As such a pressure roller, a ceramic roller composed of a shaft core and a cylindrical layer of ceramics containing calcium silicate as a main component formed on the outer circumference of the shaft core has been proposed (Japanese Patent Laid-Open No. 2006-171170). Gazette). This ceramic roller has low thermal conductivity and sufficient strength.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2006-171170</text></patcit>

<p> However, the ceramic roller having a cylindrical layer having calcium silicate as a matrix has a problem that the strength is lowered and the thermal conductivity is deteriorated in a normal storage state. Especially in a humid environment, this problem tends to be particularly prominent.</p><p> Therefore, an object of the present invention is to provide a ceramic roller capable of suppressing a decrease in strength and a deterioration in thermal conductivity under standing, and a method for producing the same.</p>

<p> In such a situation, as a result of diligent studies, the present inventors have found that in a ceramic roller used in a thermal fixing device of an electrophotographic apparatus using a charged image, (1) a heat insulating layer (cylindrical layer) having calcium silicate as a matrix. ) Has a large number of OH groups on the surface and the wall surface of the voids, so that it exhibits hydrophilicity and has the property of easily adsorbing moisture in the atmosphere. We have found that the conductivity deteriorates and (3) the adsorption of water can be greatly suppressed by forming a hydrophobic group on the surface of the cylindrical layer, and the present invention has been completed.</p><p> That is, the present invention is a ceramic roller used in a thermal fixing device of an electrophotographic apparatus using a charged image, and comprises a shaft core and a ceramic cylindrical layer formed on the outer peripheral side of the shaft core. Provided is a ceramic roller characterized by having a hydrophobic group on the surface and inside of the cylindrical layer.</p><p> Further, the present invention is a ceramic roller used in a thermal fixing device of an electrophotographic apparatus using a charged image, from a shaft core and a cylindrical body layer made of porous ceramics formed on the outer peripheral side of the shaft core. Therefore, the cylindrical layer provides a ceramic roller characterized by being water-repellent.</p><p> Further, the present invention includes a step I for preparing a slurry or an aqueous kneaded product by mixing a raw material containing heat-resistant fibers, a water-repellent treatment agent and water, a step II for obtaining a molded product from the slurry or the aqueous kneaded product, and a shaft. It provides a method for manufacturing a ceramics roller, which comprises a step III of forming a cylindrical layer around a core, and a step III.</p><p> Further, the present invention includes a step IV for preparing a slurry or an aqueous kneaded product by mixing a raw material containing heat-resistant fibers and water, a step V for obtaining a molded product from the slurry or the aqueous kneaded product, and a cylindrical body around the axis. The VI step of forming the layer, the VII step of immersing the molded product obtained in the V step or the cylindrical body layer obtained in the VI step in an impregnating solution containing a water repellent treatment agent, and the VII step obtained. The present invention provides a method for producing a ceramic roller, which comprises a step VIII of baking a water-repellent molded body or a cylindrical body layer.</p>

<p> According to the ceramic roller of the present invention, since hydrophobic groups are formed on the surface and inside of the cylindrical layer, the adsorption of moisture in the atmosphere can be suppressed. Therefore, it is possible to suppress the decrease in strength and the deterioration of thermal conductivity of the cylindrical layer at 25 to 40 ° C and 50 to 90% RH.</p>

The ceramic roller of the present invention comprises a shaft core and a ceramic cylindrical layer in this order from the center to the outside. In the present invention, ceramics refers to a material containing a non-metallic inorganic material as a main component. In the present invention, the shaft core is not particularly limited as long as it is a metal or hard resin having rigidity to withstand use, and examples thereof include iron, stainless steel, aluminum, copper, brass, carbon steel, polycarbonate, and hard nylon. ..

In the present invention, the cylindrical layer made of porous ceramics formed on the outer peripheral side of the shaft core is a cylindrical layer having a hydrophobic group or a water-repellent treated cylindrical layer, and has water repellency. Moreover, it has high heat insulation, high heat resistance, and high strength represented by low thermal conductivity and low heat capacity. Examples of the material of the cylindrical layer include ceramics containing calcium silicate as a main component and heat-resistant fibers as reinforcing fibers. Among them, ceramics containing calcium silicate as a main component and heat-resistant fibers as reinforcing fibers are high. It is preferable in terms of strength and low thermal conductivity. The cylindrical layer may be a single cylinder, a laminate in which block-shaped cylinders are laminated in the longitudinal direction of the shaft core, or a laminate in which ring-shaped sheet pieces are laminated in the longitudinal direction of the shaft core. Good.

In ceramics containing calcium silicate as a main component and heat-resistant fibers as reinforcing fibers, a compound produced by hydrothermally reacting a silicic acid raw material and a calcium raw material in the presence of water is preferable as the calcium silicate. .. Examples of calcium silicate crystals include zonotrite crystals, tovamorite crystals, and amorphous CSH crystals. In particular, a molded product made of zonotrite crystals is lightweight, has a very high specific strength, and is excellent in heat resistance and heat insulating properties. Therefore, it is preferable. The zonotrite crystals are the same as those described in Japanese Patent Application Laid-Open No. 2007-272051, and they are aggregated and bonded to form secondary particles, but they are flattened in the cylindrical layer in the ceramic roller of the present invention. Existing.

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

In addition to calcium silicate and heat-resistant fibers, a reinforcing material, a filler, a lightweight aggregate, and the like may be added to the cylindrical layer at an arbitrary blending ratio, if necessary. Examples of the reinforcing material include cement, gypsum and the like, examples of the filler include talc, diatomaceous earth, fly ash and the like, and examples of the lightweight aggregate include microsilica, pearlite, silas balloon, glass balloon and the like. The blending amount thereof is, for example, 5 to 95 parts by mass, preferably 20 to 60 parts by mass, and 0 to 36 parts by mass of the reinforcing material, preferably 0 to 36 parts by mass, with respect to 100 parts by mass of the secondary particles of the zonotrite crystal. 7 to 15 parts by mass, 0 to 30 parts by mass of filler, and 0 to 30 parts by mass of lightweight aggregate.

In the ceramic roller of the present invention, examples of the hydrophobic group formed on the surface and inside of the cylindrical layer include a group generated by the reaction between the OH group existing in the cylindrical layer and the reactive silicone. The "surface" refers to the apparent surface (outer peripheral surface) of the cylindrical layer, and the "inside" refers to the wall surface of the porous voids other than the above surface. Further, the water-repellent treated cylindrical layer can be obtained by an internal addition type manufacturing method or a post-impregnation manufacturing method described later. By having a hydrophobic group in the cylindrical layer or having a water-repellent treated cylindrical layer, the adsorption of moisture in the atmosphere can be suppressed, and at 25 to 40 ° C and 50 to 90% RH. It is possible to suppress a decrease in the strength of the cylindrical layer and a deterioration in thermal conductivity. The hydrophobic group formed in the cylindrical layer can be confirmed by an analytical means such as FT-IR under known analytical conditions. For example, in the present invention, the state in which the hydrophobic group is present is 2900 cm by FT-IR analysis.^-1It can be confirmed by the fact that absorption by CH expansion and contraction vibration is obtained in the vicinity. In the case of a water-repellent cylindrical layer, the analysis result before the water-repellent treatment and the analysis result after the water-repellent treatment are compared and 3600 to 3750 cm.^-1The nearby OH group absorption band is decreasing and 2900 cm^-1It can be confirmed by the fact that absorption by CH expansion and contraction vibration is obtained in the vicinity. In addition, 3600 ~ 3750cm^-1It is more preferable that the OH group absorption band in the vicinity has disappeared.

The ceramic roller of the present invention is composed of a shaft core and a cylindrical layer of ceramics in this order from the center to the outside. The method of fixing the cylindrical body layer to the shaft core is not particularly limited, and the fixing method is to sandwich the cylindrical body layer mounted on the shaft core from the flanges on both sides with a predetermined pressing force, and press-fit the cylindrical body layer into the shaft core. A method of fixing the cylindrical body layer to the shaft core with an adhesive, and a method of combining these fixing means can be mentioned.

In the ceramic roller of the present invention, the bulk density of the ceramic in the cylindrical layer is usually 0.05 to 0.7 g / cm.³, Preferably 0.25 to 0.5 g / cm³Is. The heat capacity of the ceramics in the cylindrical layer is 0.04 to 0.65 J / K · cm.³, Preferably 0.04 ~ 0.4J / K · cm³Is. The thermal conductivity of the ceramics in the cylindrical layer is 0.01 to 0.15 W / m · K, preferably 0.06 to 0.12 W / m · K.

Heat capacity (KJ / cm³) Can be calculated from the value of bulk density by crushing the sample and measuring the specific heat of 50 g of the sample using a high temperature sample dropping type specific heat measuring device. In addition, the thermal conductivity (W / m · K) of the ceramics in the cylindrical layer is a flat plate-like test with a width of 100 mm, a thickness of 20 mm, and a length of 50 mm, which is the same density as when the ceramic roller is used. The thermal conductivity (W / m · K) of the ceramic roller consisting of the shaft core and the cylindrical layer on the surface of the body is the rapid thermal conductivity (W / m · K) of the surface of the ceramic roller on the cylindrical layer according to JIS R2618 Transient Hot Wire Method. It was measured at room temperature with a rate meter QTM-500 (manufactured by Kyoto Electronics Industry Co., Ltd.). The cylindrical layer may be composed of ceramic layers having different bulk densities and heat capacities. For example, the portion close to the outer peripheral surface may be a ceramic layer having a heat capacity relatively lower than that of the inside.

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

Next, the method for manufacturing the ceramic roller of the present invention will be described. The ceramic roller manufacturing method of the present invention includes an internal addition type manufacturing method in which a water repellent treatment agent is added during the formation of the cylindrical body layer, and a hydrophobic group on the surface of the cylindrical body layer after the cylindrical body layer is formed. A post-impregnation method for forming the above can be mentioned.

The internal addition type manufacturing method includes step I to prepare a slurry by mixing raw materials containing heat-resistant fibers, a water repellent treatment agent, and water, step II to obtain a cylindrical molded body from the slurry, and around the shaft core. Examples thereof include a method having a step III of forming a cylindrical layer.

In step I, a slurry or water-based kneaded product containing heat-resistant fibers and calcium silicate can be used. Of these, a slurry containing heat-resistant fibers and secondary particles of zonotrite crystals is preferable because of its high strength and low thermal conductivity. A reinforcing material, a filler, a lightweight aggregate, or the like may be added as an optional component to the slurry or the water-based kneaded product. By adding such an optional component, a calcium silicate crystal-containing molded product having higher strength can be obtained. Examples of the calcium silicate and heat-resistant fibers to be blended in the slurry or the water-based kneaded product, or optional components, are the same as those described in the description of the ceramic roller of the present invention. The blending amount of these in the slurry or the aqueous kneaded product is 5 to 95 parts by mass, preferably 20 parts by mass of the heat-resistant fiber in the cylindrical layer after drying or baking, for example, with respect to 100 parts by mass of the secondary particles of the zonotrite crystal. The composition is such that the amount is ~ 60 parts by mass, the reinforcing material is 0 to 36 parts by mass, preferably 7 to 15 parts by mass, the filler is 0 to 30 parts by mass, and the lightweight aggregate is 0 to 30 parts by mass.

Examples of the water repellent treatment agent used in Step I include reactive silicone oil. Examples of the reactive silicone oil include alkoxy-based silicone oil, methylhydrogen silicone oil, and organic-modified silicone oil such as amino-modified silicone oil. Among them, alkoxy-based silicone oil is used as the internal reactive silicone oil. Suitable. Specific examples of the reactive silicone oil for internal use include "BY16-606" (manufactured by Toray Dow Corning) and "BY16-846" (manufactured by Toray Dow Corning). Since the alkoxy-based silicone oil has a Si-OR group, it reacts with water in the slurry to replace it with a Si-OH group, and then bonds with a solid surface OH group of calcium silicate by a hydrolysis reaction. Since the groups are oriented toward the surface of the solid, it exhibits high water repellency and is suitable. The blending amount of these in the slurry may be an amount sufficient for the surface of the cylindrical layer after drying or baking to exhibit water repellency, and is appropriately selected, but generally forms the cylindrical layer. It is 0.1 to 10 parts by weight, preferably 0.5 to 7 parts by weight, and more preferably 1.0 to 5.0 parts by weight with respect to 100 parts by weight of the raw material (solid content).

Step II is a step of obtaining a molded product from a slurry or an aqueous kneaded product. As a method for obtaining a molded product from the slurry, a known method such as a wet press method, a suction dehydration method or a papermaking method can be applied. As a method for obtaining a molded product from an aqueous kneaded product, a known method such as an extrusion molding method can be applied. The molded product obtained by these methods is a ring-shaped sheet piece, a plate shape, a square columnar shape, a columnar shape, or the like, and is processed into a cylindrical shape as needed. The processing into a cylindrical shape may be performed after mounting on the shaft core. The molded product obtained by the above method can be dried (baked) by a known technique. The drying conditions are usually 50 to 250 ° C for 1 to 24 hours, preferably 100 to 220 ° C for 3 to 10 hours. By this drying, the water repellent treatment agent reacts with the OH groups of the cylindrical molded body to form hydrophobic groups on the surface of the cylindrical molded body and the inner wall of the voids. As a result, the cylindrical layer does not adsorb moisture in the atmosphere, and it is possible to suppress a decrease in strength and a deterioration in thermal conductivity at 25 to 40 ° C and 50 to 90% RH.

Step III is a step of forming a cylindrical layer around the axis. Examples of the method of forming the cylindrical layer around the axis include a method of bonding by press fitting or using an adhesive, and a method of fixing by compression with a flange. The press-fit may be such that the insertion load per circumference of the inner diameter of the cylindrical layer is 0 to 80 N / cm. Insertion resistance is hardly generated by press-fitting to this extent. In this case, the shaft core and the cylindrical body layer are fixed by the frictional resistance between the flange surface of the shaft core and the end surface of the cylindrical body layer. Other press-fitting methods and fixing with an adhesive may be performed by a known method.

Post-impregnation methods include step IV to prepare a slurry or water-based kneaded product by mixing raw materials containing heat-resistant fibers and water, step V to obtain a molded product from the slurry or water-based kneaded product, and a cylindrical body around the axis. The VI step of forming the layer, the VII step of immersing the molded product obtained in the V step or the cylindrical body layer obtained in the VI step in an impregnating solution containing a water repellent treatment agent, and the VII step obtained. Examples thereof include a method having a step VIII of baking a water-repellent molded product or a cylindrical body layer.

The IV step is the same except that the water repellent treatment agent is not included in the I step, and the description thereof will be omitted. Further, the V step and the VI step are the same as those of the II step and the III step, and the description thereof will be omitted.

Step VII is a step of immersing the molded product obtained in step V or the cylindrical layer obtained in step VI in an impregnating liquid containing a water repellent treatment agent, and among them, the cylindrical layer obtained in step VI is used. Immersion in an impregnating liquid containing a water repellent treatment agent is preferable from the viewpoint of high production efficiency. The impregnating liquid is a liquid containing a diluent and a water repellent treatment agent. As the water repellent treatment agent, the same water repellent treatment agent as that used in the internal addition type manufacturing method can be used, but a reactive silicone oil for post-impregnation is preferable. Specific examples of the reactive silicone oil for post-impregnation include "KF99" (manufactured by Shin-Etsu Chemical Co., Ltd.) and "SH1107" (manufactured by Toray Dow Corning Co., Ltd.). In particular, methylhydrogen silicone oil has a SiH group in the molecule, so it is particularly reactive, reacts with OH groups on the solid surface at a relatively low temperature, and after the reaction, the methyl group is oriented toward the surface of the solid. Therefore, it exhibits high water repellency and is suitable.

The diluent is not particularly limited as long as it does not react with the water repellent treatment agent and volatilizes in the drying step, and examples thereof include hexane, acetone, and xylene. The dilution ratio of the water repellent treatment agent in the impregnating liquid is appropriately adjusted in consideration of impregnation efficiency, drying efficiency, etc., but is generally 5 to 20 times. As the impregnation method, a known method such as a method of completely immersing the material to be treated in the impregnating liquid for a predetermined time can be applied. The impregnating liquid may contain a known acid catalyst that promotes the hydrolysis of the reactive silicone oil.

Step VIII is a step of baking a water-repellent molded product or a cylindrical body layer. By carrying out step VIII, the water repellent treatment agent reacts with the OH groups of the molded product or the cylindrical body layer to form hydrophobic groups on the surface and inside of the molded product or the cylindrical body layer. As a result, the cylindrical layer does not adsorb moisture in the atmosphere, and it is possible to suppress a decrease in the strength of the cylindrical layer and a deterioration in thermal conductivity at 25 to 40 ° C and 50 to 90% RH. If the water-repellent molded body is a cylindrical body, it is attached to the shaft core as it is, and if it has a shape other than the cylindrical body, it is processed into a cylindrical body and then attached to the shaft core.

As a pretreatment for step VIII, it is preferable to carry out an air-drying treatment for 1 hour or more because the hydrolysis of the reactive silicone oil proceeds reliably.

In the reaction of the reactive silicone oil with the calcium silicate surface OH group, the reactive silicone oil is first hydrolyzed in the presence or absence of an acid catalyst. The hydroxyl group of the hydrolysis product and the calcium silicate surface OH group are then dehydrated and condensed to form a hydrophobic group on the surface of the cylinder or cylinder layer.

In the above manufacturing method, after mounting the molded piece on the shaft core, a fluororesin layer such as a PFA resin film, a silicone rubber layer, and a surface layer such as a glass layer are further formed on the outer periphery of the cylindrical body layer by a known method. Can be coated.

When an OH group is present in the cylindrical layer of the ceramic roller, it adsorbs moisture in the atmosphere, and the adsorbed water exists between the particles constituting the cylindrical layer. In this case, the van der Waals force acting between the particles (F = -A × D / (12 × Z)²) (In the formula, F; van der Waals force, A; substance eigenvalue, D; converted particle size, Z; interparticle surface distance), the interparticle distance Z becomes large, and F decreases. Therefore, for example, if a ceramic roller containing calcium silicate as a main component is left in a high humidity environment, its strength will decrease. On the other hand, in the ceramic roller of the present invention, since the hydrophobic group is formed in the cylindrical layer, the adsorption of moisture in the atmosphere can be suppressed. Therefore, even if it is left in a high humidity environment, the strength of the cylindrical layer does not decrease and the thermal conductivity does not deteriorate, and the thermal conductivity is small and the heat insulating property is excellent. It can be used for ceramic rollers that require heat insulation, which are used in heat fixing devices mounted on devices. That is, as applications in which the ceramic roller of the present invention can be used, for example, a pressure roller, a transfer roller, an auxiliary roller, a drive roller, a peeling roller, a tension roller, a drive roller, a guide roller, etc. Can be mentioned.

Next, the present invention will be described in more detail with reference to examples, but this is merely an example and does not limit the present invention.

(Generation of zonotrite crystals) Quick lime was put into hot water at 90 ° C, which is 24 times the amount of quick lime as a calcareous raw material, and digested for 30 minutes while stirring with a rotor rotating at 160 rpm to obtain lime milk. Next, CaO / SiO was added to the obtained lime milk with silica stone powder (Izu silica stone special powder D) as a siliceous raw material.₂Add so that the molar ratio is 1.0, and at the same time, add 30 times the total amount of quicklime and silica stone powder to make a uniform slurry, and stir at 120 rpm in the autoclave while the pressure inside the container is 16 kg / cm.²The mixture was hydrothermally reacted for 4 hours. The solid matter in the obtained slurry was substantially composed of zonotrite crystals, and formed spherical secondary particles having a diameter of 30 to 130 μm in which a large number of needle-like crystals, which were primary particles, were gathered.

(Preparation of slurry) 70 parts by weight of secondary particles of the above slurry zonotrite crystals, 5 parts by weight of Portland cement (ordinary Portland cement, manufactured by Ube-Mitsubishi Cement Co., Ltd.), 25 parts by weight of glass fiber with a fiber diameter of 6 mm (CS6J-888S, manufactured by Nitto Boseki Co., Ltd.) And 2 parts by weight of methylalkylethoxysilylalkylsiloxane "BY16-606" (manufactured by Toray Dow Corning Co., Ltd.) were uniformly mixed to obtain a slurry. Then, the slurry is poured into a suction molding mold having the bottom of the mesh, and about 40 kgf / cm while performing suction dehydration.²After wet pressing at the pressure of, dry (bak) at 100 ° C for 5 hours, and the density is 0.35 g / cm.³, A sheet-shaped heat insulating paper having a thickness of 1.4 mm was obtained.

(Manufacturing of ceramic rollers) From the obtained sheet-shaped heat insulating paper, 267 ring-shaped sheet pieces having an outer diameter of 39.5 mm and an inner diameter of 22.5 mm were obtained by punching. In the punching process, 20 pieces were picked using a punching machine having a double cylindrical blade, and punching was performed 5 times at a time. Next, ring-shaped sheet pieces were inserted one after another into a stainless steel shaft core having a shaft diameter of 22.0 mm, and 267 split molded pieces were connected to each other. The 267 split molded pieces were compressed and fixed with flanges from both sides to obtain ceramic rollers. The water absorption rate and thermal conductivity of the obtained ceramic rollers were measured. The compression strength was measured by cutting a sheet of heat insulating paper into 5 cm x 5 cm pieces. Table 1 shows the results of water absorption, compressive strength and thermal conductivity. The water absorption rate, compressive strength, and thermal conductivity were all measured one week after the steady state under the two conditions of 25 ° C × 50% RH and 40 ° C × 90% RH. Since the compressive strength and thermal conductivity were dried at 110 ° C in advance for the convenience of measurement, the results immediately after drying at 110 ° C are also shown. In addition, when FT-IR analysis was performed on the circumferential surface of the ring-shaped sheet piece, it was 3600 to 3750 cm.^-1The nearby OH group absorption band disappeared, 2900 cm^-1Absorption by CH expansion and contraction vibration was obtained in the vicinity, and the presence of hydrophobic groups could be confirmed.

The same method as in Example 1 was carried out except that 4 parts by weight of methylalkylethoxysilylalkylsiloxane was used instead of 2 parts by weight of methylalkylethoxysilylalkylsiloxane. The results are shown in Table 1.

(Slurry preparation process) 5 parts by weight of Portland cement (ordinary Portland cement, manufactured by Ube-Mitsubishi Cement Co., Ltd.) and 10 parts by weight of glass fiber (CS6J-888S, Nitto) with respect to 70 parts by weight of the secondary particles of the zonotrite crystal obtained in Example 1. Add 15 parts by weight of small-diameter glass fiber (Q fiber, manufactured by Manville) and 0.05 parts by weight of coagulant (Sunflock N-OP, manufactured by Sanyo Kasei Kogyo Co., Ltd.) and mix uniformly. A cement slurry was obtained.

(Manufacturing of ceramic rollers) The slurry obtained in the slurry preparation process is machined with a long net paper machine to form paper, and then approximately 4 kgf / cm.²Press at the pressure of 0.35 g / cm and dry.³, A sheet-shaped heat insulating paper having a thickness of 1.4 mm was obtained. From the obtained sheet-shaped heat insulating paper, 267 ring-shaped sheet pieces having an outer diameter of 39.5 mm and an inner diameter of 22.5 mm were obtained by punching. For the punching process, a punching machine having a double cylindrical blade was used, and 20 pieces were picked and punched 14 times at one time. Next, ring-shaped sheet pieces were inserted one after another into a stainless steel shaft core having a shaft diameter of 22.0 mm, and 267 split molded pieces were connected to each other. The 267 split molded pieces were compressed and fixed with flanges from both sides to obtain ceramic rollers. The 267 split molded pieces (cylindrical layer) have a total weight of 50 g and a volume of 125 cm.³, Density 0.4g / cm³, True density 2.3g / cm³, Porosity 82.6%, Porosity 103 cm³Met.

(Immersion process) Methyl hydrogen silicone oil with a specific gravity of 1.0 ("KF99" (manufactured by Shin-Etsu Chemical Co., Ltd.)) is placed in hexane with a specific gravity of 0.68 (special grade manufactured by Kanto Chemical Co., Inc.) and diluted at a dilution ratio of 20 times to a density of 0.7 g / cm.³The impregnating solution of was produced. The ceramic roller obtained by the above method was completely immersed in this impregnating solution for 2 hours. After impregnation for 2 hours, no bubbles were generated in the impregnating solution. The total amount of the heat insulating layer and the impregnating liquid was 118 g, the impregnated amount was 68 g, and the impregnation rate was 96%.

The ceramic roller impregnated with the impregnating liquid was air-dried for 1 hour or more to volatilize hexane and hydrolyze methylhydrogen silicone oil. Then, baking was performed at 180 ° C. for 5 hours. The weight of the ceramic roller after processing is 54 g, and the density is 0.43 g / cm.³Met. The obtained ceramic rollers were evaluated in the same manner as in Example 1. The results are shown in Table 1.

The same method as in Example 3 was carried out except that the dilution ratio was set to 5 times instead of 20 times. The results are shown in Table 1. An FT-IR analysis was performed on the circumferential surfaces of the ceramic rollers of Examples 3 and 4, and the thickness was 3600 to 3750 cm.^-1The nearby OH group absorption band disappeared, 2900 cm^-1Absorption by CH expansion and contraction vibration was obtained in the vicinity, and the presence of hydrophobic groups could be confirmed.

Comparative example 1 The procedure was the same as in Example 1 except that the impregnation step was omitted. The results are shown in Table 1.

<tables num="1"><img file="JP2009300503A_D0001.tif" /></tables>

In Comparative Example 1, which shows a conventional example, 2.4% moisture absorption occurred when left in an environment of 25 ° C × 50% RH, and 6.4% moisture absorption occurred at 40 ° C × 90% RH. Examples 1 to 4 have lower water absorption at 25 ° C × 50% RH (relative humidity) and 40 ° C × 90% RH (relative humidity), higher compression strength, and thermal conductivity than Comparative Example 1. Was small. In the case of Comparative Example 1, under high humidity conditions, the compression strength of 3.6 was reduced to 2.9 MPa.

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