Smooth low density paperboard

Abstract

A paperboard product has at least two or three plies. One of the plies has at least 25% by weight bulky cellulosic fibers. Another of the plies is an outer ply and has an outer surface having a Parker PrintSurf measurement of between 3 and 6μ when measured at 10 kg/cm 2 using a soft backing surface. The paperboard product has a density no greater than 0.5 grams per cubic centimeter. An embodiment has a caliper in the range of 0.4 and 1.2 mm. An embodiment has a basis weight in the range of 200 to 500 grams per square meter. A method for making the paperboard product by passing the web through a soft nip calender and an extended nip calender which can be a shoe calender under conditions which provide the surface and density properties.

1 . A paperboard product comprising at least two plies 
 said paperboard product having a density no greater that 0.5 grams per cubic centimeter,    one of said plies comprising a least 25% by weight bulky cellulosic fibers,    another of said plies being an outer ply and having an outer surface having a Parker PrintSurf measurement of between 3 and 6μ when measured at 10 kg/cm 2  using a soft backing surface.    
   
   
       2 . The paperboard product of  claim 1  in which said paperboard product has a caliper in the range of 0.4 and 1.2 mm.  
   
   
       3 . The paperboard product of  claim 1  in which said paperboard product has a basis weight in the range of 200 to 500 grams per square meter.  
   
   
       4 . The paperboard product of  claim 1  in which the density of said paperboard product is between 0.3 and 0.45 grams per cubic centimeter.  
   
   
       5 . The paperboard product of  claim 4  in which said paperboard product has a caliper in the range of 0.4 and 1.2 mm.  
   
   
       6 . The paperboard product of  claim 4  in which said paperboard product has a basis weight in the range of 200 to 500 grams per square meter.  
   
   
       7 . The paperboard product of  claim 1  in which the density of said paperboard product is between 0.35 and 0.4 grams per cubic centimeter.  
   
   
       8 . The paperboard product of  claim 7  in which said paperboard product has a caliper in the range of 0.4 and 1.2 mm.  
   
   
       9 . The paperboard product of  claim 7  in which said paperboard product has a basis weight in the range of 200 to 500 grams per square meter.  
   
   
       10 . The paperboard product of  claim 1  further comprising at least three plies, and said one of said plies comprises a center ply.  
   
   
       11 . The paperboard product of  claim 10  in which said paperboard product has a caliper of 0.4 and 1.2 mm.  
   
   
       12 . The paperboard product of  claim 10  in which said paperboard product has a basis weight in the range of 200 to 500 grams per square meter.  
   
   
       13 . The paperboard product of  claim 10  in which the density of said paperboard product is between 0.3 and 0.45 grams per cubic centimeter.  
   
   
       14 . The paperboard product of  claim 13  in which said paperboard product has a caliper in the range of 0.4 and 1.2 mm.  
   
   
       15 . The paperboard product of  claim 13  in which said paperboard product has a basis weight in the range of 200 to 500 grams per square meter.  
   
   
       16 . The paperboard product of  claim 10  in which the density of said paperboard product is between 0.35 and 0.4 grams per cubic centimeter.  
   
   
       17 . The paperboard of  claim 16  in which said paperboard product has a caliper in the range of 0.4 and 1.2 mm.  
   
   
       18 . The paperboard product of  claim 16  in which said paperboard product has a basis weight in the range of 200 to 500 grams per square meter.