Expanded-graphite sheet

Abstract

An expanded-graphite sheet whose thermal conductivity in its surfacewise directions is relatively uniform and higher than its thermal conductivity in its perpendicular direction can be produced efficiently at relatively low cost. Because the expanded-graphite sheet is made of expanded graphite alone and has thermal conductivity in parallel direction of 350 W/(m·K) or more, its thermal conductivity in parallel direction is much higher than its thermal conductivity in a perpendicular direction; therefore, it is suitable for the conduction and diffusion of heat. Besides, the expanded-graphite sheet can be produced easily, in a short time, efficiently, at relatively low cost.

1 - 15 . (canceled) 
     
     
         16 . An expanded-graphite sheet with a thermal conductivity of 350 W/(m·K) or more in a direction parallel to the surface and
 with an arithmetic mean surface roughness of less than 5 μm, 
 wherein the difference between the highest and lowest values of local thermal conductivities at various spots on the expanded-graphite sheet is 10% or less of the overall mean thermal conductivity thereof. 
 
     
     
         17 . The expanded-graphite sheet of  claim 16  having an electromagnetic-wave-shielding effect of 60 dBμV/m or more in the frequency range of 100-800 MHz. 
     
     
         18 . The expanded-graphite sheet of  claim 16  with a total impurity content of 10 ppm or less. 
     
     
         19 . The expanded-graphite sheet of  claim 16 , with a bulk density of 1.6 Mg/m 3  or more. 
     
     
         20 . A compressed expanded-graphite sheet consisting of a single sheet of expanded-graphite,
 wherein the compressed expanded-graphite sheet is made by compressing the single sheet of expanded-graphite, and   a thermal conductivity of the compressed expanded-graphite sheet is 350 W/(m·K) or more in a direction parallel to the surface of the compressed expanded-graphite sheet, said compressed expanded-graphite sheet having an arithmetic mean surface roughness of less than 5 μm.   
     
     
         21 . The compressed expanded-graphite sheet of  claim 20  wherein the difference between the highest and lowest values of local thermal conductivities at various spots on the compressed expanded-graphite sheet is 10% or less of the overall mean thermal conductivity thereof. 
     
     
         22 . The compressed expanded-graphite sheet of  claim 20  having an electromagnetic-wave-shielding effect of 60 dBμV/m or more in the frequency range of 100-800 MHz. 
     
     
         23 . The compressed expanded-graphite sheet of  claim 20  with a total impurity content of 10 ppm or less. 
     
     
         24 . The compressed expanded-graphite sheet of  claim 20  with a bulk density of 1.6 Mg/m 3  or more. 
     
     
         25 . The compressed expanded-graphite sheet of  claim 20  with a bulk density of 1.75 Mg/m 3  or more. 
     
     
         26 . The compressed expanded-graphite sheet of  claim 21 , wherein the compressed expanded-graphite sheet has an area of at least 40,000 mm 2 . 
     
     
         27 . The compressed expanded-graphite sheet of  claim 26 , wherein the difference between the highest and the lowest values of the local thermal conductivities are defined by using nine 25 mm by 25 mm square test pieces cut from the compressed expanded-graphite sheet. 
     
     
         28 . A compressed expanded-graphite sheet consisting of a single sheet of expanded-graphite,
 wherein the single sheet of expanded-graphite consists of:
 expanded-graphite; 
 optionally a binder; and 
 optionally an impurity content, 
   the compressed expanded-graphite sheet is made by compressing the single sheet of expanded-graphite,   a thermal conductivity of the compressed expanded-graphite sheet is 350 W/(m·K) or more in a direction parallel to the surface of the compressed expanded-graphite sheet, and   the difference between the highest and lowest values of local thermal conductivities at various spots on the compressed expanded-graphite sheet is 10% or less of the overall mean thermal conductivity thereof.   
     
     
         29 . The compressed expanded-graphite sheet of  claim 28  having an electromagnetic-wave-shielding effect of 60 dBμV/m or more in the frequency range of 100-800 MHz. 
     
     
         30 . The compressed expanded-graphite sheet of  claim 28  with a total impurity content of 10 ppm or less. 
     
     
         31 . The compressed expanded-graphite sheet of  claim 28  with a bulk density of 1.6 Mg/m 3  or more. 
     
     
         32 . The compressed expanded-graphite sheet of  claim 28  with a bulk density of 1.75 Mg/m 3  or more. 
     
     
         33 . The compressed expanded-graphite sheet of  claim 28 , wherein the compressed expanded-graphite sheet has an area of at least 40,000 mm 2 . 
     
     
         34 . The compressed expanded-graphite sheet of  claim 33 , wherein the difference between the highest and the lowest values of the local thermal conductivities are defined by using nine 25 mm by 25 mm square test pieces cut from the compressed expanded-graphite sheet.