Patent Publication Number: US-11036168-B2

Title: Image forming method for metallic sheets

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119 to Japanese Patent Application No. 2019-051102, filed on Mar. 19, 2019 in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Embodiments of the present disclosure generally relate to an image forming method and an image forming apparatus. 
     Background Art 
     In the printing industry, to make printed materials stand out, images are printed on metallic sheets to make posters, book covers, packages, product tags, various cards, POP advertisements and store fixtures on display racks. These images have great impact and good advertising effects because the non-image portions are shiny and glittering. 
     The images are often printed on the metallic sheets by offset printing, which is suitable for large-volume printing but is not cost-effective for small-volume printing. Since the metallic sheets themselves are expensive, small-volume printing, for example, printing images on 100 metallic sheets or less, is more desirable than large-volume printing. 
     An electrophotographic image forming method is suitable for small-volume printing, but at present, rarely used for printing images on metallic sheets. One of the reasons lies in the characteristics of the image formed on the metallic sheet by the electrophotographic image forming method. Forming an image having a large image area with cyan, magenta, yellow, and black toner on the metallic sheet darkens the image and reduces the impact. 
     A countermeasure for the above-described disadvantage is to place a white layer under the image, but a general electrophotographic image forming apparatus forms images using cyan, magenta, yellow, and black toner and cannot form the white layer under the image. In contrast, recently, an industrial electrophotographic image forming apparatuses having white toner in addition to four color toners, that is, cyan, magenta, yellow, and black toner has been put into practical use. 
     SUMMARY 
     This specification describes an improved image forming method for an image forming apparatus having a fixing rotator and a pressure rotator opposite the fixing rotator. The method includes transferring white toner and color toner onto a surface of a metallic sheet having a thermal conductivity of 0.34 W/m·K or less as measured by hot-wire method to form an unfixed color toner layer layered on an unfixed white toner layer on the metallic sheet and conveying the metallic sheet, with the surface on which the white toner layer and the color toner layer are transferred facing the fixing rotator, between the fixing rotator heated and the pressure rotator to fix the white toner layer and the color toner layer onto the metallic sheet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawing, wherein: 
         FIG. 1  is a schematic explanatory diagram illustrating an example of an image forming apparatus according to the present disclosure; and 
         FIG. 2  is a schematic explanatory diagram illustrating a metallic sheet according to the present disclosure on which an unfixed color toner layer and an unfixed white toner layer are formed. 
     
    
    
     The accompanying drawing is intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawing is not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A description is provided of an image forming method and an image forming apparatus according to the present disclosure with reference to the drawing. 
     In describing embodiments illustrated in the drawing, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result. 
     Although the embodiments are described with technical limitations with reference to the attached drawing, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable. 
     Moreover, it is to be noted that the present disclosure is not to be considered limited to the following embodiments, but can be changed within the range that can be conceived of by those skilled in the art, such as other embodiments, additions, modifications, deletions, and the scope of the present disclosure encompasses any aspect, as long as the aspect achieves the operation and advantageous effect of the present disclosure. 
     The present inventors formed images on various types of metallic sheets using an electrophotographic image forming method and found that most commercially available metallic sheets do not have satisfactory adhesion between the metallic sheet and a toner layer that forms the toner image. The metallic sheets more preferable for offset printing tended to have poor adhesion. A sample having better adhesion than other samples but poor image quality was found and examined. Toner of the surface of the toner layer was sufficiently melted. 
     However, when the above-described sample was bent, separation of the toner layer from the metallic sheet in a film form was found in many parts. On the other hand, the present inventor found that a part of the toner layer did not separate from the metallic sheet in the film form even when a crack is formed in the toner layer. A detailed examination of the part of the toner layer that did not separate from the metallic sheet in the film form revealed that melted toner was intertwined with the surface layer of the metallic sheet at the interface between the surface layer of the metallic sheet and the toner layer that forms the toner image, and the toner layer and the metallic sheet adhered to each other. 
     Using the above-described metallic sheet and changing the fixing temperature, the present inventors made and bent samples on which toner images were formed and observed the interface between the surface of the metallic sheet and the toner layer forming the toner image in each sample. As a result, the present inventors found that a higher fixing temperature decreased a number of parts in which the toner layer separated from the metallic sheet in the film form and provided better adhesion, in which the toner was intertwined with the surface layer of the metallic sheet at the interface between the surface layer of the metallic sheet and the toner layer that forms the toner image. On the other hand, the present inventors noticed that discoloration and deformation of the metallic sheet itself occur as the fixing temperature increases. Therefore, simply increasing the fixing temperature could not give a high-quality image. 
     The present inventors found that, to improve adhesion between the metallic sheet and the toner layer that forms the toner image, it is important for the toner to be intertwined with the surface layer of the metallic sheet at the interface between the surface layer of the metallic sheet and the toner layer and, for the toner to be intertwined with the surface layer of the metallic sheet, sufficiently increasing temperature at the interface is important. Therefore, the present inventors examined the temperature at the interface between the toner layer and the surface of the metallic sheet and found that the temperature was lower than expected. The present inventors investigated why the temperature becomes low at the interface between the surface of the metallic sheet and the toner layer that forms the toner image and found that the heat transmitted from the toner layer diffuses inside the metallic sheet to prevent the temperature at the interface between the surface of the metallic sheet and the toner layer from being kept sufficiently high. 
     As a result, the present inventors found that lower thermal conductivity of the metallic sheet results in better adhesion between the toner layer and the metallic sheet and high-quality images in an image forming apparatus not having a heater in a pressure roller, which results in the present disclosure. 
     That is, with reference to  FIG. 2 , the image forming method according to the present disclosure includes transferring white toner and color toner onto a surface of a metallic sheet  30  having a thermal conductivity of 0.34 W/m·K or less as measured by hot-wire method to form an unfixed color toner layer  42  layered on an unfixed white toner layer  41  on the metallic sheet  30  as illustrated in  FIG. 2  and conveying the metallic sheet  30 , with the surface on which the white toner layer  41  and the color toner layer  42  are transferred facing the fixing rotator, between the fixing rotator heated and the pressure rotator to fix the white toner layer  41  and the color toner layer  42  onto the metallic sheet  30 . 
     In the electrophotographic image forming method, when the metallic sheet bearing the toner image passes between a heated roller or a heated belt (hereinafter, referred to as a fixing belt) and a pressure roller, the transferred toner image contacts the fixing belt, and heat and pressure fix the toner image on the metallic sheet. 
     There are two types of fixing devices, that is, one that heats a pressure roller to a target temperature and the other that does not heat the pressure roller. In the fixing device having a heating mechanism in the pressure roller, the heated fixing belt heats the front surface of the sheet bearing the toner image, and the pressure roller also heats the back surface of the sheet. 
     Therefore, the above-described fixing device has advantages of high productivity of image formation and easy temperature control of the fixing belt but consumes a lot of energy. In addition, when a heated pressure rotator such as the heated pressure roller fixes the toner image onto the sheet, the fixing temperature may be too high, which may cause discoloration or deformation of the metallic sheet itself, and good quality may not be obtained. The heated pressure rotator may degrade the quality of the back surface of the sheet opposite to the front surface of the sheet bearing the white toner layer and the color toner layer. 
     The thermal conductivity of the metallic sheet  30  used in the image forming method of the present disclosure may be measured by the hot-wire method. The hot-wire method is a simple measuring method and can measure the thermal conductivity of the metallic sheet with good reproducibility. In the present disclosure, the measurement of the thermal conductivity of the metallic sheet by the hot-wire method was performed using a quick thermal conductivity meter QTM-500 manufactured by KYOTO ELECTRONICS MANUFACTURING CO.LTD, at 23±1° C. and 50±5%. The metallic sheet was placed on a reference sheet of known thermal conductivity, and the apparatus probe of the QTM-500 was placed on a metallic luster surface that is a surface which a metallic layer of the metallic sheet is seen. From the measurement results using quartz glass, silicon rubber, and silicon sponge rubber as the reference plate, the thermal conductivity is obtained. 
     The thermal conductivity of the metallic sheet  30  in the image forming method of the present embodiment is 0.34 W/m·K or less, and preferably 0.23 W/m·K to 0.33 W/m·K. When the thermal conductivity of the metallic sheet is larger than 0.34 W/m·K, the heat from the fixing belt diffuses to the entire metallic sheet, and adhesion between the toner layer and the surface of the metallic sheet deteriorates. Generally, the metallic sheet has a larger thermal capacity than ordinary thick paper because a plastic film including a metal layer is laminated on one side of the sheet. 
     The thermal conductivity of the metallic sheet may be adjusted by materials of the metallic sheet, thickness of each layer, and the like, and is greatly affected by the material and thickness of an adhesive layer. Appropriately changing these parameters can set the thermal conductivity of the metallic sheet to the above-described range. 
     The metallic sheet  30  in the present embodiment includes the metallic layer  33 , which is also referred to as the metallic luster layer. The metallic layer  33  includes a metal and functions as a layer having metallic luster. 
     Examples of the metal contained in the metallic layer  33  include metal such as aluminum, silver, copper, and gold, alloys, aluminum dyes, and organic metals. Aluminum is preferable in terms of cost, whereas copper or gold are preferable to obtain colored metallic luster. 
     The metallic sheet  30  in the present embodiment includes a resin layer  34 , which is also referred to as a plastic layer  34 , a plastic film, or the like. 
     When the metallic layer  33  and the plastic layer  34  are laminated, the metallic layer  33  may be on either surface of the plastic layer  34 , or a plurality of metallic layers  33  may be formed. Since the metallic sheet  30  having beautiful light reflection can be produced at low cost, preferably, the metallic layer  33  is laminated on one side of the plastic layer  34  and bonded to a base material  31  such as coated paper or high-quality paper. Since the metallic layer  33  has a higher thermal conductivity than other layers, it is preferable that the metallic layer  33  be between the plastic layer  34  and the base material  31  in order to prevent diffusion of heat in the surface of the metallic sheet  30 . 
     The metallic layer  33  near the surface of metallic sheet  30  with low electrical resistivity may cause a discharge in a transfer process of the electrophotographic image forming method, which may degrade image quality and cause a failure of the image forming apparatus. The metallic layer  33  laminated on the plastic layer  34  by vapor deposition, sputtering, or the like tends to have low mechanical strength. Therefore, the metallic layer  33  is preferably formed at a position away from the surface of the metallic sheet to some extent d as illustrated in  FIG. 2 . 
     Based on a consideration of the above factors, the surface of the metallic layer  33  is preferably formed at a position of 10 μm to 100 μm from the surface of the metallic sheet  30  in the laminating direction Y in  FIG. 2 , more preferably 12 μm to 90 μm. The metallic sheet  30  having the surface of the metallic layer  33  in the preferable range becomes a print product having a beautiful metallic luster without causing discharge in the transfer process. 
     The metallic layer  33  may be formed by vapor deposition, a vacuum process by sputtering, electroless plating, painting with metallic ink, or applying a metal film or an alloy film with an adhesive. Preferably, the vacuum process or painting with metallic ink forms the metallic layer  33  because the metallic layer  33  is uniformly formed in a low-cost way. 
     The thickness of the metallic layer  33  is appropriately selected depending on the metallic luster, cost and the like required for the metallic sheet  30 , but is preferably from 0.02 μm to 2 μm, more preferably from 0.03 μm to 1 μm, and still more preferably from 0.03 μm to 0.5 μm. The thickness of the metallic layer  33  is usually uniform but may be changed depending on positions on the metallic sheet  30  to form a pattern of the metallic layer  33  or an arbitrary shape of the metallic layer  33 . 
     Preferably, the plastic layer  34  is transparent and has heat resistance to the heat applied in the fixing process in the electrophotographic process. 
     The plastic layer  34  that is the plastic film is made of, for example, a polyester film, a polyvinyl alcohol film, a polyvinylidene chloride film, or the like. The polyester film is preferred in consideration of transparency, thermal characteristics, mechanical strength, processability, and cost. 
     The film thickness of the plastic layer  34  may be appropriately changed depending on handleability, production cost, degree of metallic tone required for the metallic sheet, and the like. The film thickness is preferably from 10 μm to 100 μm, more preferably from 12 μm to 100 μm, and still more preferably from 12 μm to 80 μm. Setting the film thickness in the above preferable range prevents discharge in the transfer process, makes the metallic sheet  30  easier to process, makes the light reflection more beautiful, allows for easy post-processing such as folding, and prevents the cost from increasing. 
     The metallic sheet  30  in the present embodiment may include an anchor coat layer. The anchor coat layer is placed on the surface of the plastic layer. 
     High fixing temperatures can improve adhesion between the plastic layer  34  made of, for example, polyester and the toner layer made of toner including base particle made of polyester or styrene acrylic. However, the anchor coat layer disposed on the surface of the plastic layer  34  can lower the fixing temperature while maintaining good adhesion. 
     The anchor coat layer may be made of polyester resin, acrylic resin, styrene acrylic resin, polymethacrylate resin, paint made of the above-described resin, or adhesive made of the above-described resin. Among them, polyester resin and styrene acrylic resin are preferable because transparency and adhesion to toner are improved. 
     The thickness of the anchor coat layer is preferably from 0.1 μm to 15 μm, more preferably from 0.2 μm to 10 μm, and still more preferably from 0.5 μm to 9 μm. Generally, the thicker the anchor coat layer is, the better adhesion between the anchor layer and the toner layer tends to be. On the other hand, the thicker anchor layer causes toner to easily move during the fixing process, which degrades the resolution of the image. Therefore, the thickness of the anchor layer is determined based on the configuration of the image forming apparatus or the like. 
     The metallic sheet  30  in the present embodiment may be made by laminating the plastic layer  34  on the metallic layer  33  formed on the base material  31  by coating, vacuum forming, and the like. From the viewpoint of productivity and production cost, the metallic sheet  30  is preferably produced by bonding the plastic film having the metallic layer  33  to the base material  31  with an adhesive. The above-described process forms an adhesive layer  32  as illustrated in  FIG. 2 . 
     The adhesive that is heat-stable during the fixing process and has high adhesive strength may be used. A pressure-sensitive adhesive having flexibility is preferable because the metallic sheet  30  is often bent. Examples of adhesives include vinyl acetate resin, ethylene-vinyl acetate copolymer resin (EVA), acrylic resin, or the like. Above all, acrylic pressure-sensitive adhesive is preferable because the acrylic pressure-sensitive adhesive has good heat stability and a large thermal capacity that prevent heat from transferring between the plastic layer  34  and the base material  31  and decrease the thermal conductivity of the metallic sheet  30 . The above-described adhesives are applied to at least one of the base material  31  and the plastic layer  34 . After application of the adhesives, the plastic layer  34  coated with the adhesive is overlaid on the base material  31  or the metallic layer  33  and pressed. When the adhesive is reactive or contains a solvent, energy such as heat is appropriately applied to cure the adhesive layer  32 . The adhesive is preferably the pressure-sensitive adhesive because the metallic sheet  30  can be made by applying the pressure-sensitive adhesive between the base material  31  and the plastic layer  34  having the metallic layer  33  and pressing the plastic layer  34  or the base material  31 . The above-described acrylic pressure-sensitive adhesive is preferable because the acrylic pressure-sensitive adhesive is inexpensive and has workability that gives high processing accuracy. 
     The thickness of the adhesive layer  32  is preferably 0.8 μm to 15 μm, more preferably 1 ∪m to 12 μm. The thermal conductivity of the metallic sheet  30  is greatly affected by the thickness of the adhesive layer  32 . The thicker the adhesive layer  32  formed by the pressure-sensitive adhesive is, the lower the thermal conductivity of the metallic sheet  30  is. The adhesive layer  32  having the thickness of 0.8 μm or more easily follows irregularities on the surface of the base material  31 , which can improve the adhesive strength. Setting the thickness of the adhesive layer  32  to 0.8 μm or more can easily reduce the thermal conductivity of the metallic sheet  30  to 0.34 W/m·K or less and improve adhesion between the toner layer and the metallic sheet  30 . The adhesive layer having the thickness less than 0.8 μm increases the thermal conductivity of the metallic sheet and may degrade adhesion between the toner layer and the metallic sheet. A thickness of the adhesive layer of less than 0.8 μm tends to cause incomplete adhesion between the base material and the plastic layer having the metallic layer and partially different reflection of light, which may not give a beautiful metallic sheet. 
     Setting the thickness of the adhesive layer  32  to 15 μm or less can prevent the production cost from increasing and improve the mechanical strength of the metallic sheet. In contrast, setting the thickness of the adhesive layer to larger than 15 μm results in uneven thickness of the adhesive layer and prevents an adhesive surface of the plastic layer having the metallic layer becoming smooth. This may cause partially unnatural reflection of light and detract from the beauty of the metallic sheet. In addition, deformation of the metallic sheet may occur when the metallic sheet is handled or processed. 
     Examples of the base material  31  of the metallic sheet  30  include plain paper, coated paper, and high-quality paper. Preferably, the base material  31  is coated paper having a smooth surface considering adhesion between the base material  31  and the plastic layer  34  having a metallic layer  33  and the reflectance of metallic sheet  30 . 
     Considering the use of the metallic sheet  30 , it is preferable that the base material  31  has a certain thickness, that is, 100 GSM to 350 GSM in the basis weight of the base material  31 . 
     As described above, the metallic sheet  30  in the present embodiment preferably has a configuration including the base material  31 , the adhesive layer  32  formed on the base material  31 , the metallic layer  33  including metal and formed on the adhesive layer  32 , and the resin layer  34  (the plastic layer  34 ) formed on the metallic layer  33 . In addition, it is more preferable to provide the anchor coat layer on the plastic layer  34 . The above configuration can improve adhesion between the toner layer and the metallic sheet  30  and the flexibility and workability of the metallic sheet  30 . 
     The image forming method of the present embodiment provides high quality toner image having the toner layer that sufficiently adheres to the metallic sheet  30 . The toner image in the present embodiment is obtained by transferring a white toner layer  41  on the metallic sheet  30 , transferring a color toner layer  42  on the white toner layer  41 , and fixing the toner layers  41  and  42  onto the metallic sheet  30 . In the present embodiment, the color toner layer  42  including the white toner layer  41  as the lowermost layer is transferred to the metallic sheet, but only the white toner layer  41  may be transferred to a part of the metallic sheet  30 , or only the color toner layer  42  may be transferred to a part of the metallic sheet  30 . 
     Next, with reference to  FIG. 1 , a description is given of an image forming apparatus  1  that uses the image forming method according to the present disclosure. 
     Image Reader 
     An image reader  11  optically reads an image recorded on a sheet and generates image data. Specifically, the image reader  11  irradiates the original with light. A reading sensor such as a charge coupled device (CCD) or a contact image sensor (CIS) receives the light reflected by the original and reads the light into image data. The image data is information defining a toner image to be formed on a recording medium such as the sheet and is constructed of electrical color separation image signals indicating red (R), green (G), and blue (B), respectively. 
     As illustrated in  FIG. 1 , the image reader  11  includes an exposure glass  111  and a reading sensor  112 . The original bearing the image is placed on the exposure glass  111 . The reading sensor  112  reads the image on the original placed on the exposure glass  111  into image data. 
     Image Forming Device 
     A detailed description is now given of a construction and operation of an image forming device  12  of the image forming apparatus  1 . The image forming device  12  adheres toner to an outer circumferential surface of an intermediate transfer belt  143  of a transfer device  14  according to the image data created by the image reader  11  or image data received by the network I/F, thus forming the toner image on the outer circumferential surface of the intermediate transfer belt  143 . 
     The image forming device  12  includes an image forming unit  120 C to form a toner image using a developer having a cyan (C) color toner, an image forming unit  120 M to form a toner image using a magenta (M) color toner, an image forming unit  120 Y to form a toner image using a yellow (Y) color toner, an image forming unit  120 K to form a toner image using a black (K) color toner, and an image forming unit  120 W to form a toner image using a white (W) toner. 
     At least one of the cyan toner, the magenta toner, the yellow toner, and the black toner is hereinafter referred to as color toner or process color toner. The color toner includes charged resin particles containing a coloring material such as a pigment and a dye. 
     The white toner includes charged resin particles containing a white pigment. 
     The image forming device  12  may include an image forming unit to form a toner image using a developer having a transparent clear toner or a color toner other than the cyan toner, the magenta toner, the yellow toner, and the black toner. 
     An arbitrary image forming unit selected from the image forming units  120 C,  120 M,  120 Y,  120 K, and  120 W is hereinafter referred to as an image forming unit  120 . 
     The image forming unit  120 C includes a toner supply  121 C, a photoconductor drum  122 C, a charger  123 C, an exposure device  124 C, a developing device  125 C, a discharger  126 C, and a cleaner  127 C. 
     The toner supply  121 C contains the cyan toner to be supplied to the developing device  125 C A conveying screw disposed inside the toner supply  121 C is driven to convey a predetermined amount of the cyan toner to the developing device  125 C. 
     The charger  123 C uniformly changes an outer circumferential surface of the photoconductor drum  122 C. The exposure device  124 C forms an electrostatic latent image on the outer circumferential surface of the photoconductor drum  122 C according to the image data sent from the controller  10 . The developing device  125 C adheres the cyan toner to the electrostatic latent image formed on the outer circumferential surface of the photoconductor drum  122 C, visualizing the electrostatic latent image into a cyan toner image. The photoconductor drum  122 C contacts the intermediate transfer belt  143  at a contact point at which the photoconductor drum  122 C rotates in the same direction as a rotational direction of the intermediate transfer belt  143 . 
     The charger  123 C uniformly charges the outer circumferential surface of the photoconductor drum  122 C. 
     The exposure device  124 C irradiates the outer circumferential surface of the photoconductor drum  122 C charged by the charger  123 C with light according to a dot area rate (e.g., a halftone area rate) of the cyan toner image that is determined by the controller  10 , thus forming the electrostatic latent image on the photoconductor drum  122 C. 
     The developing device  125 C adheres the cyan toner supplied from the toner supply  121 C to the electrostatic latent image formed on the outer circumferential surface of the photoconductor drum  122 C by the exposure device  124 C, visualizing the electrostatic latent image into the cyan toner image. 
     After the cyan toner image is primarily transferred onto the intermediate transfer belt  143 , the discharger  126 C discharges the outer circumferential surface of the photoconductor drum  122 C. The cleaner  127 C removes residual toner failed to be transferred onto the intermediate transfer belt  143  and therefore remaining on the outer circumferential surface of the photoconductor drum  122 C that is discharged by the discharger  126 C, from the photoconductor drum  122 C. 
     The image forming unit  120 M includes a toner supply  121 M, a photoconductor drum  122 M, a charger  123 M, an exposure device  124 M, a developing device  125 M, a discharger  126 M, and a cleaner  127 M. The toner supply  121 M contains the magenta toner. Since the photoconductor drum  122 M, the charger  123 M, the exposure device  124 M, the developing device  125 M, the discharger  126 M, and the cleaner  127 M operate similarly to the photoconductor drum  122 C, the charger  123 C, the exposure device  124 C, the developing device  125 C, the discharger  126 C, and the cleaner  127 C, a description of an operation of the photoconductor drum  122 M, the charger  123 M, the exposure device  124 M, the developing device  125 M, the discharger  126 M, and the cleaner  127 M is omitted. 
     The image forming unit  120 Y includes a toner supply  121 Y, a photoconductor drum  122 Y, a charger  123 Y, an exposure device  124 Y, a developing device  125 Y, a discharger  126 Y, and a cleaner  127 Y. The toner supply  121 Y accommodates the yellow toner. Since the photoconductor drum  122 Y, the charger  123 Y, the exposure device  124 Y, the developing device  125 Y, the discharger  126 Y, and the cleaner  127 Y operate similarly to the photoconductor drum  122 C, the charger  123 C, the exposure device  124 C, the developing device  125 C, the discharger  126 C, and the cleaner  127 C, a description of an operation of the photoconductor drum  122 Y, the charger  123 Y, the exposure device  124 Y, the developing device  125 Y, the discharger  126 Y, and the cleaner  127 Y is omitted. 
     The image forming unit  120 K includes a toner supply  121 K, a photoconductor drum  122 K, a charger  123 K, an exposure device  124 K, a developing device  125 K, a discharger  126 K, and a cleaner  127 K. The toner supply  121 K contains the black toner. Since the photoconductor drum  122 K, the charger  123 K, the exposure device  124 K, the developing device  125 K, the discharger  126 K, and the cleaner  127 K operate similarly to the photoconductor drum  122 C, the charger  123 C, the exposure device  124 C, the developing device  125 C, the discharger  126 C, and the cleaner  127 C, a description of an operation of the photoconductor drum  122 K, the charger  123 K, the exposure device  124 K, the developing device  125 K, the discharger  126 K, and the cleaner  127 K is omitted. 
     The image forming unit  120 W includes a toner supply  121 W, a photoconductor drum  122 W, a charger  123 W, an exposure device  124 W, a developing device  125 W, a discharger  126 W, and a cleaner  127 W. The toner supply  121 W contains the white toner. Since the photoconductor drum  122 W, the charger  123 W, the exposure device  124 W, the developing device  125 W, the discharger  126 W, and the cleaner  127 W operate similarly to the photoconductor drum  122 C, the charger  123 C, the exposure device  124 C, the developing device  125 C, the discharger  126 C, and the cleaner  127 C, a description of an operation of the photoconductor drum  122 W, the charger  123 W, the exposure device  124 W, the developing device  125 W, the discharger  126 W, and the cleaner  127 W is omitted. 
     An arbitrary toner supply selected among the toner supplies  121 C,  121 M,  121 Y,  121 K, and  121 W is hereinafter referred to as a toner supply  121 . An arbitrary photoconductor drum selected among the photoconductor drums  122 C,  122 M,  122 Y,  122 K, and  122 W is hereinafter referred to as a photoconductor drum  122 . An arbitrary charger selected among the chargers  123 C,  123 M,  123 Y,  123 K, and  123 W is hereinafter referred to as a charger  123 . An arbitrary exposure device selected among the exposure devices  124 C,  124 M,  124 Y,  124 K, and  124 W is hereinafter referred to as an exposure device  124 . An arbitrary developing device selected among the developing devices  125 C,  125 M,  125 Y,  125 K, and  125 W is hereinafter referred to as a developing device  125 . An arbitrary discharger selected among the dischargers  126 C,  126 M,  126 Y,  126 K, and  126 W is hereinafter referred to as a discharger  126 . An arbitrary cleaner selected among the cleaners  127 C,  127 M,  127 Y,  127 K, and  127 W is hereinafter referred to as a cleaner  127 . 
     The order of toner to be transferred to the intermediate transfer belt  143  is such that white toner is transferred last, and the order of toners other than white toner, that is, the cyan toner, the magenta toner, the yellow toner, and the black toner does not matter. That is, the image forming unit  120 W is arranged at the last position. In the present embodiment, a white toner is transferred to a portion to which at least one of the cyan toner image, the magenta toner image, the yellow toner image, and the black toner image is transferred. 
     Sheet Feeder 
     A detailed description is now given of a construction and operation of a sheet feeder  13  of the image forming apparatus  1 . The sheet feeder  13  supplies the sheet to the transfer device  14 . The sheet feeder  13  includes a sheet tray  131 , a feed roller  132 , a feed belt  133 , and a registration roller pair  134 . 
     The sheet tray  131  loads a plurality of sheets serving as one example of recording media. As the feed roller  132  rotates, the feed roller  132  moves the sheet from the sheet tray  131  to the feed belt  133 . For example, the feed roller  132  picks up and feeds an uppermost sheet of the plurality of sheets loaded on the sheet tray  131  onto the feed belt  133 . 
     The feed belt  133  conveys the uppermost sheet picked up by the feed roller  132  to the transfer device  14 . The registration roller pair  134  feeds the sheet conveyed by the feed belt  133  to the transfer device  14  at a time when a toner image formed on the intermediate transfer belt  143  reaches the transfer device  14 . 
     Transfer Device 
     A detailed description is now given of a construction and operation of the transfer device  14  in the image forming apparatus  1 . The transfer device  14  primarily transfers a toner image formed on the photoconductor drum  122  by the image forming device  12  onto the intermediate transfer belt  143  and secondarily transfers the toner image transferred on the intermediate transfer belt  143  onto the sheet. 
     The transfer device  14  includes a driving roller  141 , a driven roller  142 , the intermediate transfer belt  143 , primary transfer rollers  144 C,  144 M,  144 Y,  144 K, and  144 W, a secondary transfer roller  145 , and a secondary transfer opposing roller  146 . 
     The intermediate transfer belt  143  is looped over the driving roller  141  and the driven roller  142 . As a driver drives and rotates the driving roller  141 , the driving roller  141  rotates the intermediate transfer belt  143  looped over the driving roller  141 . The driving roller  141  and the driven roller  142  support the intermediate transfer belt  143 . As the driving roller  141  rotates the intermediate transfer belt  143 , the intermediate transfer belt  143  rotates the driven roller  142 . 
     As the driving roller  141  rotates the intermediate transfer belt  143  looped over the driving roller  141  and the driven roller  142 , the intermediate transfer belt  143  rotates while contacting the photoconductor drums  122 . As the intermediate transfer belt  143  rotates while contacting the photoconductor drums  122 , the cyan, magenta, yellow, black, and white toner images formed on the photoconductor drums  122  are primarily transferred onto the outer circumferential surface of the intermediate transfer belt  143 . 
     The primary transfer rollers  144 C,  144 M,  144 Y,  144 K, and  144 W are disposed opposite the photoconductor drums  122 C,  122 M,  122 Y,  122 K, and  122 W via the intermediate transfer belt  143 , respectively. As the primary transfer rollers  144 C,  144 M,  144 Y,  144 K, and  144 W rotate clockwise in  FIG. 1 , the primary transfer rollers  144 C,  144 M,  144 Y,  144 K, and  144 W rotate the intermediate transfer belt  143 . 
     The secondary transfer roller  145  rotates while the secondary transfer roller  145  and the secondary transfer opposing roller  146  sandwich the intermediate transfer belt  143  and the sheet. The secondary transfer opposing roller  146  rotates while the secondary transfer roller  145  and the secondary transfer opposing roller  146  sandwich the intermediate transfer belt  143  and the sheet. 
     Fixing Device 
     A detailed description is now given of a construction and operation of a fixing device  15  in the image forming apparatus  1 . The fixing device  15  fixes the toner image secondarily transferred by the transfer device  14  on the sheet. The fixing device  15  applies heat and pressure to the toner image on the sheet to melt and fix a resin component of toner of the toner image on the sheet. After the fixing device  15  fixes the toner image secondarily transferred by the transfer device  14  on the sheet, the toner of the toner image on the sheet attains a stable state. 
     The fixing device  15  includes a conveyance belt  151 , a fixing belt  152 , a fixing roller  153 , a fixing belt driving roller  154 , a fixing roller opposing roller  155 , and a heater  156 . 
     The conveyance belt  151  as a conveyor conveys the sheet bearing the toner image secondarily transferred by the transfer device  14  to a fixing nip formed between the fixing roller opposing roller  155  and the fixing belt  152  supported by the fixing roller  153 . The fixing belt  152  is looped over the fixing roller  153  and the fixing belt driving roller  154 . As the fixing roller  153  and the fixing belt driving roller  154  rotate, the fixing roller  153  and the fixing belt driving roller  154  rotate the fixing belt  152 . While the sheet is conveyed by the conveyance belt  151  through the fixing nip formed between the fixing belt  152  and the fixing roller opposing roller  155  that is disposed opposite the fixing roller  153  via the fixing belt  152 , the fixing belt  152  and the fixing roller opposing roller  155  fix the toner image on the sheet under heat and pressure. 
     In this embodiment, the fixing belt  152  and the fixing roller  153  are used as the fixing rotator, but the configuration of the fixing rotator is not limited thereto. For example, only the fixing roller may be used without using the fixing belt. A heater may be disposed inside the fixing roller. 
     The fixing belt driving roller  154  and the fixing roller  153  support the fixing belt  152 . As the fixing belt driving roller  154  rotates, the fixing belt driving roller  154  rotates the fixing belt  152 . 
     In the present embodiment, the fixing roller opposing roller  155  is used as the pressing rotator. The fixing roller opposing roller  155  is disposed opposite the fixing roller  153  via the fixing belt  152 . The fixing belt  152  and the fixing roller opposing roller  155  sandwich the sheet while the sheet is conveyed through the fixing nip. 
     The heater  156  is disposed inside the fixing belt driving roller  154  to heat the fixing belt driving roller  154 . The heater  156  heats the fixing belt driving roller  154 , the temperature of the fixing belt driving roller  154  rise, and the fixing belt  152  is heated. The heated fixing belt  152  rotates and heats the sheet. 
     The heater  156  is disposed inside the fixing belt driving roller  154  in  FIG. 1  but may be disposed anywhere as long as the heater  156  can heat the fixing belt  152 . For example, if the heater  156  is an induction heater (an IH heater), the heater  156  may be outside the fixing belt driving roller  154  and the fixing belt  152 . Without using the fixing belt  152 , only the fixing roller  153  with the heater  156  inside may be used. 
     Sheet Ejection Device 
     A detailed description is now given of a construction of a sheet ejection device  16  in the image forming apparatus  1 . The sheet ejection device  16  ejects the sheet bearing the toner image fixed in the fixing device  15  to an outside of the image forming apparatus  1 . The sheet ejection device  16  includes an ejection belt  161 , an ejection roller  162 , an outlet  163 , and an output tray  164 . 
     The ejection belt  161  conveys the sheet bearing the fixed toner image to the outlet  163 . The ejection roller  162  ejects the sheet conveyed by the ejection belt  161  onto the output tray  164  through the outlet  163 . The output tray  164  stacks the sheet ejected by the ejection roller  162 . 
     Control Panel 
     A detailed description is now given of a construction of the control panel  17  of the image forming apparatus  1 . The control panel  17  includes a display panel portion  171  and an operation portion  172 . The display panel portion  171  displays settings, selection screens, and the like. The display panel portion  171  includes a touch panel with which the user inputs an instruction. The operation portion  172  includes ten keys with which the user inputs various settings for image formation and a start key with which the user inputs an instruction to start a print job. 
     EXAMPLES 
     Further understanding can be obtained by reference to certain specific examples which are provided herein for the purpose of illustration only and are not intended to be limiting. 
     Example 1 
     Aluminum was vapor-deposited on one surface of a polyethylene terephthalate (PET) film having a thickness of 64 μm, and styrene acrylic resin was applied as the anchor coat layer to have a thickness of 6.5 μm on a surface opposite to the aluminum vapor-deposited surface. The acrylic pressure-sensitive adhesive was provided on the surface of a coated paper having a basis weight of 275 GSM to form a layer having a thickness of 10 μm. The surface of the acrylic pressure-sensitive adhesive layer on the coated paper was bonded to the aluminum-deposited surface of the PET film to produce the metallic sheet. 
     The quick thermal conductivity meter QTM-500 manufactured by KYOTO ELECTRONICS MANUFACTURING CO., LTD measured the thermal conductivity of the produced metallic sheet with the metallic glossy surface facing upward at 23±1° C. and 50±5%. Quartz glass, silicon rubber, and silicon sponge rubber were used as reference plates. The thermal conductivity of the produced metallic sheet was 0.247 W/m·K. 
     A toner image was formed on the produced metallic sheet by the electrophotographic image forming method. A color production printer Pro C7200 S manufactured by Ricoh Co. Ltd. was customized and used as the image forming apparatus. The Pro C7200 S is the image forming apparatus as illustrated in  FIG. 1 , does not have the heater inside a pressure roller, and uses the white toner, the cyan toner, the magenta toner, the yellow toner, and the black toner to form the toner image. Generally, when the Pro C7200 S forms the toner image on a thick sheet like the metallic sheet, the paper sensor of the Pro C7200 S detects that the sheet is the thick sheet, and the controller slows down the print speed to increase the amount of heat supplied to the toner image, which is called a medium speed mode. In the customized Pro C7200 S in the present embodiment, the signal of the paper sensor was blocked to form the toner image on the metallic sheet in a normal print speed, that is, a high-speed mode. 
     First, in the high-speed mode, the Pro C7200 superimposed a solid white image and a magenta solid image to form a toner image, and the present inventors evaluated adhesion between the metallic sheet and a toner layer that forms the toner image. The toner image given by the above was very clear, and adhesion between the toner layer forming the toner image and the metallic sheet was excellent. Next, the present inventors turned signal lines of the paper sensor to normal, and the Pro C7200 sequentially superimposed a white solid image, a cyan solid image, a magenta solid image, a yellow solid image, and a black solid image on the metallic sheet to form a superimposed image in the medium speed mode. The toner image given by the above was very clear, and adhesion between the toner layer forming the toner image and the metallic sheet was excellent. 
     Example 2 
     A metallic sheet in the example 2 was produced by setting a thickness of the acrylic pressure-sensitive adhesive to 1.1 mm and setting other conditions to the same as those in the example 1. The thermal conductivity of the produced metallic sheet was 0.318 W/m·K. In the same manner as in the example 1, toner images were formed on the metallic sheets in the medium speed mode and the high-speed mode. In each of samples, the toner image given by the above was very clear, and adhesion between the toner layer forming the toner image and the metallic sheet was excellent. 
     Example 3 
     Aluminum was vapor-deposited on one surface of a polyvinyl alcohol (PVA) film having a thickness of 42 μm, and styrene acrylic resin was applied as the anchor coat layer to have a thickness of 5.2 μm on a surface opposite to the aluminum vapor-deposited surface. The acrylic pressure-sensitive adhesive was provided on the surface of the coated paper having a basis weight of 300 GSM to form a layer having a thickness of 7 μm. The surface of the acrylic pressure-sensitive adhesive layer on the coated paper was bonded to the aluminum-deposited surface of the PVA film to produce the metallic sheet. The quick thermal conductivity meter QTM-500 manufactured by KYOTO ELECTRONICS MANUFACTURING CO., LTD measured the thermal conductivity of the produced metallic sheet with the metallic glossy surface facing upward at 23±1° C. and 50±5%. Quartz glass, silicon rubber, and silicon sponge rubber were used as the reference plates. The thermal conductivity of the produced metallic sheet was 0.271 W/m·K. In the same manner as in the example 1, toner images were formed on the metallic sheets in the medium speed mode and the high-speed mode. In each of samples, the toner image given by the above was very clear, and adhesion between the toner layer forming the toner image and the metallic sheet was excellent. 
     Example 4 
     Aluminum was vapor-deposited on one surface of the PET film having a thickness of 16 μm, and polyester resin was applied as the anchor coat layer to have a thickness of 2.3 μm on the surface opposite to the aluminum vapor-deposited surface. The acrylic pressure-sensitive adhesive was provided on the surface of the coated paper having a basis weight of 300 GSM to form a layer having a thickness of 8 μm. The surface of the acrylic pressure-sensitive adhesive layer on the coated paper was bonded to the aluminum-deposited surface of the PET film to produce the metallic sheet. The quick thermal conductivity meter QTM-500 manufactured by KYOTO ELECTRONICS MANUFACTURING CO., LTD measured the thermal conductivity of the produced metallic sheet with the metallic glossy surface facing upward at 23±1° C. and 50±5%. Quartz glass, silicon rubber, and silicon sponge rubber were used as the reference plates. The thermal conductivity of the produced metallic sheet was 0.302 W/m·K. In the same manner as in the example 1, toner images were formed on the metallic sheets in the medium speed mode and the high-speed mode. In each of samples, the toner image given by the above was very clear, and adhesion between the toner layer forming the toner image and the metallic sheet was excellent. 
     Example 5 
     Aluminum was vapor-deposited on one surface of the PET film having a thickness of 11 μm, and polymethacrylate resin was applied as the anchor coat layer to have a thickness of 0.5 μm on the surface opposite to the aluminum vapor-deposited surface. An acrylic adhesive was provided at 8 μm on the surface of a coated paper having a basis weight of 310 GSM. The surface of the acrylic pressure-sensitive adhesive layer on the coated paper was bonded to the aluminum-deposited surface of the PET film to produce the metallic sheet. The quick thermal conductivity meter QTM-500 manufactured by KYOTO ELECTRONICS MANUFACTURING CO., LTD measured the thermal conductivity of the produced metallic sheet with the metallic glossy surface facing upward at 23±1° C. and 50±5%. Quartz glass, silicon rubber, and silicon sponge rubber were used as the reference plates. The thermal conductivity of the produced metallic sheet was 0.336 W/m·K. In the same manner as in the example 1, toner images were formed on the metallic sheets in the medium speed mode and the high-speed mode. In each of samples, the toner image given by the above was very clear, and adhesion between the toner layer forming the toner image and the metallic sheet was weaker than other results described above at a part of the image but enough in a practical use. 
     Comparative Example 1 
     Aluminum was vapor-deposited on one surface of the PET film having a thickness of 8 μm, and polymethacrylate resin was applied as the anchor coat layer to have a thickness of 0.5 μm on the surface opposite to the aluminum vapor-deposited surface. The acrylic pressure-sensitive adhesive was provided on the surface of the coated paper having a basis weight of 310 GSM to form a layer having a thickness of 0.7 μm. The surface of the acrylic pressure-sensitive adhesive layer on the coated paper was bonded to the aluminum-deposited surface of the PET film to produce the metallic sheet. The quick thermal conductivity meter QTM-500 manufactured by KYOTO ELECTRONICS MANUFACTURING CO., LTD measured the thermal conductivity of the produced metallic sheet with the metallic glossy surface facing upward at 23±1° C. and 50±5%. Quartz glass, silicon rubber, and silicon sponge rubber were used as the reference plates. The thermal conductivity of the produced metallic sheet was 0.355 W/m·K. In the same manner as in the example 1, toner images were formed on the metallic sheets in the medium speed mode and the high-speed mode. Each of obtained samples had an insufficient adhesion between the toner layer and the metallic sheet. Tables 1A to 1 C illustrate the configuration of each layer of the metallic sheets, the thermal conductivities, and whether the pressing rotator has the heater in the above-described Examples and the Comparative Example. Tables 1A to 1 C also illustrate above-described information in the following Examples and Comparative Examples. 
     Examples 6 to 9 and Comparative Example 2 
     Aluminum was vapor-deposited on one surface of the PET film, and polyester resin was applied as the anchor coat layer to have a thickness of 10 μm on the surface opposite to the aluminum vapor-deposited surface. The acrylic pressure-sensitive adhesive was provided on the surface of the coated paper having a basis weight of 290 GSM. The surface of the acrylic pressure-sensitive adhesive layer on the coated paper was bonded to the aluminum-deposited surface of the PET film to produce the metallic sheet. As illustrated in Tables 1A to 1 C below, the thickness of the PET film and the thickness of the acrylic pressure-sensitive adhesive were changed to produce metallic sheets having different thermal conductivities. The present inventors evaluated adhesion between each produced metallic sheet and the toner layer that forms the toner image in the same manner as in Example 1. Table 2 illustrates the results of evaluation of adhesion. 
     Example 10 
     A metallic sheet in the example 10 was produced by setting a thickness of the acrylic pressure-sensitive adhesive to 14.5 μm and setting other conditions to the same as those in the example 1. The thermal conductivity of the produced metallic sheet was 0.229 W/m·K. In the same manner as in the example 1, toner images were formed on the metallic sheet in the medium speed mode and the high-speed mode. In each of samples, the toner image given by the above was very clear, and adhesion between the toner layer forming the toner image and the metallic sheet was excellent. 
     Comparative Example 3 
     The same metallic sheet as in Example 10 was produced. Pro C7200 S was customized to have a heating mechanism in the pressure roller. In the same manner as in the example 1, toner images were formed on the metallic sheet in the medium speed mode and the high-speed mode. In each of samples, adhesion between the toner layer forming the toner image and the metallic sheet was enough, but reflection of the metallic sheet becomes ununiform, which made it impossible to get a beautiful toner image on the metallic sheet. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1A 
               
             
            
               
                   
                   
               
               
                   
                 ADHESIVE LAYER 
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 BASE MATERIAL 
                   
                 THICKNESS 
                 METALLIC 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 TYPE 
                 GSM 
                 TYPE 
                 [μm] 
                 LAYER 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 EXAMPLE 1 
                 COATED 
                 275 
                 ACRYLIC 
                 10 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 EXAMPLE 2 
                 COATED 
                 275 
                 ACRYLIC 
                 1.1 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 EXAMPLE 3 
                 COATED 
                 300 
                 ACRYLIC 
                 7 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 EXAMPLE 4 
                 COATED 
                 300 
                 ACRYLIC 
                 8 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 EXAMPLE 5 
                 COATED 
                 310 
                 ACRYLIC 
                 8 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 COMPARATIVE 
                 COATED 
                 310 
                 ACRYLIC 
                 0.7 
                 ALUMINUM 
               
               
                 EXAMPLE 1 
                 PAPER 
               
               
                 EXAMPLE 6 
                 COATED 
                 290 
                 ACRYLIC 
                 2.5 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 EXAMPLE 7 
                 COATED 
                 290 
                 ACRYLIC 
                 1.5 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 EXAMPLE 8 
                 COATED 
                 290 
                 ACRYLIC 
                 1.0 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 EXAMPLE 9 
                 COATED 
                 290 
                 ACRYLIC 
                 0.9 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 COMPARATIVE 
                 COATED 
                 290 
                 ACRYLIC 
                 0.6 
                 ALUMINUM 
               
               
                 EXAMPLE 2 
                 PAPER 
               
               
                 EXAMPLE 10 
                 COATED 
                 275 
                 ACRYLIC 
                 14.5 
                 ALUMINUM 
               
               
                   
                 PAPER 
               
               
                 COMPARATIVE 
                 COATED 
                 275 
                 ACRYLIC 
                 14.5 
                 ALUMINUM 
               
               
                 EXAMPLE 3 
                 PAPER 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1B 
               
             
            
               
                   
                   
               
               
                   
                 PLASTIC LAYER 
                 ANCHOR COAT LAYER 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 THICKNESS 
                   
                 THICKNESS 
               
               
                   
                 TYPE 
                 [μm] 
                 TYPE 
                 [μm] 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 EXAMPLE 1 
                 PET 
                 64 
                 STYRENE ACRYLIC 
                 6.5 
               
               
                   
                   
                   
                 RESIN 
               
               
                 EXAMPLE 2 
                 PET 
                 64 
                 STYRENE ACRYLIC 
                 6.5 
               
               
                   
                   
                   
                 RESIN 
               
               
                 EXAMPLE 3 
                 PVA 
                 42 
                 STYRENE ACRYLIC 
                 5.2 
               
               
                   
                   
                   
                 RESIN 
               
               
                 EXAMPLE 4 
                 PET 
                 16 
                 POLYESTER RESIN 
                 2.3 
               
               
                 EXAMPLE 5 
                 PET 
                 11 
                 POLYMETHACRYLATE 
                 0.5 
               
               
                   
                   
                   
                 RESIN 
               
               
                 COMPARATIVE 
                 PET 
                 8 
                 POLYMETHACRYLATE 
                 0.5 
               
               
                 EXAMPLE 1 
                   
                   
                 RESIN 
               
               
                 EXAMPLE 6 
                 PET 
                 40 
                 POLYESTER RESIN 
                 10 
               
               
                 EXAMPLE 7 
                 PET 
                 40 
                 POLYESTER RESIN 
                 10 
               
               
                 EXAMPLE 8 
                 PET 
                 55 
                 POLYESTER RESIN 
                 10 
               
               
                 EXAMPLE 9 
                 PET 
                 60 
                 POLYESTER RESIN 
                 10 
               
               
                 COMPARATIVE 
                 PET 
                 75 
                 POLYESTER RESIN 
                 10 
               
               
                 EXAMPLE 2 
               
               
                 EXAMPLE 10 
                 PET 
                 64 
                 STYRENE ACRYLIC 
                 6.5 
               
               
                   
                   
                   
                 RESIN 
               
               
                 COMPARATIVE 
                 PET 
                 64 
                 STYRENE ACRYLIC 
                 6.5 
               
               
                 EXAMPLE 3 
                   
                   
                 RESIN 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1C 
               
               
                   
                   
               
               
                   
                 THERMAL 
                 DOES PRESSURE 
               
               
                   
                 CONDUCTIVITY 
                 ROTATOR HEAT 
               
               
                   
                 [W/m · K] 
                 SHEET? 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 EXAMPLE 1 
                 0.247 
                 NO 
               
               
                   
                 EXAMPLE 2 
                 0.318 
                 NO 
               
               
                   
                 EXAMPLE 3 
                 0.271 
                 NO 
               
               
                   
                 EXAMPLE 4 
                 0.302 
                 NO 
               
               
                   
                 EXAMPLE 5 
                 0.336 
                 NO 
               
               
                   
                 COMPARATIVE 
                 0.355 
                 NO 
               
               
                   
                 EXAMPLE 1 
               
               
                   
                 EXAMPLE 6 
                 0.293 
                 NO 
               
               
                   
                 EXAMPLE 7 
                 0.314 
                 NO 
               
               
                   
                 EXAMPLE 8 
                 0.329 
                 NO 
               
               
                   
                 EXAMPLE 9 
                 0.338 
                 NO 
               
               
                   
                 COMPARATIVE 
                 0.369 
                 NO 
               
               
                   
                 EXAMPLE 2 
               
               
                   
                 EXAMPLE 10 
                 0.229 
                 NO 
               
               
                   
                 COMPARATIVE 
                 0.229 
                 YES 
               
               
                   
                 EXAMPLE 3 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 ADHESION 
               
               
                   
                   
                 BETWEEN 
               
               
                   
                 THERMAL 
                 TONER LAYER 
               
               
                   
                 CONDUCTIVITY 
                 AND METALLIC 
               
               
                   
                 [W/m · K] 
                 SHEET 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 EXAMPLE 6 
                 0.293 
                 EXCELLENT 
               
               
                   
                 EXAMPLE 7 
                 0.314 
                 EXCELLENT 
               
               
                   
                 EXAMPLE 8 
                 0.329 
                 EXCELLENT 
               
               
                   
                 EXAMPLE 9 
                 0.338 
                 PARTIALLY 
               
               
                   
                   
                   
                 WEAK BUT NO 
               
               
                   
                   
                   
                 PROBLEM IN 
               
               
                   
                   
                   
                 PRACTICAL USE 
               
               
                   
                 COMPARATIVE 
                 0.369 
                 POOR 
               
               
                   
                 EXAMPLE 2 
               
               
                   
                   
               
            
           
         
       
     
     The present disclosure is not limited to the above-described embodiments, and the configuration of the present embodiment can be appropriately modified other than suggested in each of the above embodiments within a scope of the technological concept of the present disclosure. Also, the positions, the shapes, and the number of components are not limited to the embodiments, and they may be modified suitably in implementing the present disclosure. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims. 
     Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.