Thermally-insulating layers and direct thermal imaging members containing same

Abstract

Multicolor thermal imaging members are described that comprise color-forming layers that are separated by thermally-insulating layers and can be addressed with a thermal printing head in contact with a surface to form an image. The thermally-insulating layers are designed to be as thin as possible consistent with at least partially independent addressing of the color-forming layers, and are formulated so as not to lead to instabilities either before or after printing or to give rise to dimensional changes of a thermal imaging member when it is subjected to changes in temperature or humidity. Coating compositions for manufacturing such thermally-insulating layers are also provided.

1 - 8 . (canceled) 
     
     
         9 . A coating composition comprising at least 20% by weight of water-borne latex polymeric material and less than 20% by weight of a hydrophobically-modified poly (vinyl alcohol) wherein the viscosity measured at 1000 s −1  is more than 50 mPa·s and the flow behavior index n is within the range of about 0.8 to about 1. 
     
     
         10 . The coating composition of  claim 9  comprising at least 30% by weight of water-borne latex polymeric material and less than 10% by weight of a hydrophobically-modified poly (vinyl alcohol) wherein the viscosity measured at 1000 s −1  is more than 50 mPa·s and the flow behavior index n is within the range of about 0.8 to about 1. 
     
     
         11 . The coating composition of  claim 9 , further comprising an organic material that has a glass transition temperature of at least 80° C. in an amount that is at least 10% of the weight of the polymeric latex material. 
     
     
         12 . The coating composition of  claim 9  wherein said organic material is a phenolic compound with molecular weight less than 2000. 
     
     
         13 . The coating composition of  claim 9  wherein said organic material is chosen from the group consisting of 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane.