Insulating paperboard

Abstract

An insulating paperboard contains at least one layer of cellulose fibers. The one layer is at least partially composed of cellulosic fibers and synthetic fibers. The paperboard provides sufficient insulation to provide a hot water AT across the paperboard of at least 0.6° C. per 0.1 mm of caliper change. A hot cup may be produced from the insulating paperboard.

1 . An insulating paperboard comprising: 
 at least one layer of cellulosic fibers,    said at least one layer of cellulosic fibers further comprising synthetic fibers,    said cellulosic fibers being present in an amount from 40% to 95% of said at least one layer,    said synthetic fibers being present in an amount from 5% to 60% of said at least one layer,    said paperboard being sufficiently insulating to provide a hot water ΔT across said paperboard of at least 0.6° C. per 0.1 mm of caliper.    
   
   
       2 . The cellulosic fibers of  claim 1  wherein said cellulosic fibers further comprise processed cellulosic fibers.  
   
   
       3 . The processed cellulosic fibers of  claim 2  wherein said processed cellulosic fibers are selected from the group consisting of chemically 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 mercerized fibers.  
   
   
       5 . The fibers of  claim 3  wherein the processed fibers are CTMP fibers.  
   
   
       6 . The fibers of  claim 3  wherein the processed fibers are BCTMP fibers.  
   
   
       7 . The fibers of  claim 3  wherein the processed fibers are TMP fibers.  
   
   
       8 . The fibers of  claim 3  wherein the processed fibers are jet dried fibers.  
   
   
       9 . The fibers of  claim 3  wherein the processed fibers are flash dried fibers.  
   
   
       10 . The synthetic fibers of  claim 1  wherein the synthetic fibers are polyester fibers.  
   
   
       11 . The synthetic fibers of  claim 9  wherein the synthetic fibers are crimped fibers.  
   
   
       12 . The insulating paperboard of  claim 2 , wherein said paperboard has a density of less than 0.5 g/cc.  
   
   
       13 . The insulating paperboard of  claim 2 , wherein said paperboard has a basis weight of from 250 gsm to 500 gsm.  
   
   
       14 . The insulating paperboard of  claim 2 , wherein the caliper of said paperboard is greater than or equal to 0.5 mm.  
   
   
       15 . The insulating paperboard of  claim 2 , wherein said paperboard has a hot water ΔT of at least 4.5° C. at a caliper of 0.5 mm and a hot water ΔT of 8.7° C. at a caliper of at least 1 mm, said hot water ΔT being a substantially linear progression relative to caliper in the temperature range from below 4.5° C. to above 8.7° C.  
   
   
       16 . The insulating paperboard of  claim 14 , wherein said linear progression extends from a ΔT of 4.5° C. to a ΔT of 8.7° C.  
   
   
       17 . The insulating paperboard of  claim 1 , wherein said paperboard is at least a two-ply board, said at least one ply containing said cellulosic fibers and synthetic fibers.