Insulating paperboard

Abstract

An insulating paperboard contains at least one layer of cellulose fibers. The one layer is at least partially composed of crosslinked fibers and processed cellulosic fibers. The paperboard provides sufficient insulation to provide a ΔT across the paperboard of at least 3.6° C. at 0.5 mm. A hot cup may be produced from the insulating paperboard.

1 . An insulating paperboard comprising: 
 at least one layer comprising a mixture of crosslinked fibers and processed cellulosic fibers,    said crosslinked cellulosic fibers and said processed fibers being present in an amount in said mixture from 35 to 60 percent of total dry weight of fibers of said at least one layer, and    wherein said paperboard being sufficiently insulating to provide a ΔT across said paperboard of at least 3.6° C. at a caliper of 0.5 mm,    said paperboard having a density of less than 0.5 g/cc, and a basis weight of from 200 gsm to 500 gsm, and    said caliper of said paperboard being greater than or equal to 0.5 mm.    
   
   
       2 . The crosslinked fibers of  claim 1  wherein said crosslinked fibers are present in an amount of 30 to 70 percent of the total dry weight of the mixture and the processed fibers are present in an amount of 70 to 30 percent of the total dry weight of the mixture.  
   
   
       3 . The processed fibers of  claim 2  wherein the processed fibers are selected from the group consisting of chemically processed fibers, mercerized fibers, mechanically processed fibers, chemimechanically processed fibers, jet dried fibers, flash dried fibers and mixtures thereof.  
   
   
       4 . The fibers of  claim 3  wherein the processed fibers are CTMP fibers.  
   
   
       5 . The fibers of  claim 3  wherein the processed fibers are TMP fibers.  
   
   
       6 . The crosslinked fibers of  claim 1  wherein the fibers are selected from the group consisting of citric acid crosslinked fibers, polyacrylic acid crosslinked fibers and polymaleic acid crosslinked fibers.  
   
   
       7 . The crosslinked fibers of  claim 6  wherein the crosslinked fibers are polyacrylic acid crosslinked fibers.  
   
   
       8 . The crosslinked fibers of  claim 6  wherein the crosslinked fibers are citric acid crosslinked fibers.  
   
   
       9 . The insulating paperboard of  claim 1 , wherein said paperboard has a basis weight of from 250 gsm to 450 gsm.  
   
   
       10 . The insulating paperboard of  claim 1 , wherein said paperboard has a ΔT of at least 3.6° C. at a caliper of 0.5 mm and a ΔT of 9.8° C. at a caliper of 1.15 mm, said ΔT being a substantially linear progression relative to caliper in the range from below a ΔT of 3.6° C. to above a ΔT of 9.8° C.  
   
   
       11 . The insulating paperboard of  claim 10 , wherein said linear progression extends from a ΔT of 3.6° C. to a ΔT of 9.8° C.  
   
   
       12 . The paperboard of  claim 1  wherein the Taber stiffness is at least 150 g-cm.  
   
   
       13 . The paperboard of  claim 1  wherein the ZDT is at least 180 kPa.  
   
   
       14 . The insulating paperboard of  claim 1 , wherein said paperboard is at least a two-ply board, said at least one ply containing said crosslinked cellulosic fibers and processed cellulosic fibers.