Coated paper suitable for use in a sack

Abstract

There is provided a coated paper comprising a kraft paper substrate, a precoating layer provided on the kraft paper substrate and a water vapour barrier coating layer provided on the pre-coating layer. The grammage according to ISO 536:2019 of the coated paper is 65-155 g/m2, the pre-coating layer comprises inorganic filler and binder in a dry weight ratio of between 100:25 and 100:5 and the water vapour barrier coating layer comprises clay pigment and styrene-butadiene co-polymer (SBR) binder in a dry weight ratio between 100:30 and 100:80. The particle size distribution (%<2 pm) of said clay pigment is above 90 and the shape factor of said clay pigment is below 20, such as below 10.

1 . A coated paper comprising a kraft paper substrate, a pre-coating layer provided on the kraft paper substrate and a water vapor barrier coating layer provided on the pre-coating layer, wherein the grammage according to ISO 536:2019 of the coated paper is 65-155 g/m 2 , the pre-coating layer comprises inorganic filler and binder in a dry weight ratio of between 100:25 and 100:5 and the water vapor barrier coating layer comprises clay pigment and styrene-butadiene co-polymer (SBR) binder in a dry weight ratio between 100:30 and 100:80, wherein the particle size distribution (%<2 μm) of said clay pigment is above 90 and the shape factor of said clay pigment is below 20. 
     
     
         2 . The coated paper of  claim 1 , wherein the grammage according to ISO 536:2019 of the kraft paper substrate is 50-140 g/m 2 . 
     
     
         3 . The coated paper of  claim 1 , wherein the grammage according to ISO 536:2019 of the coated paper is 65-135 g/m 2 . 
     
     
         4 . The coated paper of  claim 1 , wherein the coat weight of the pre-coating layer is 4-20 g/m 2 . 
     
     
         5 . The coated paper of  claim 1 , wherein the coat weight of the water vapor barrier coating layer is 4-20 g/m 2 . 
     
     
         6 . The coated paper of  claim 1 , wherein the dry weight ratio of inorganic filler to binder in the pre-coating layer is between 100:20 and 100:8. 
     
     
         7 . The coated paper of  claim 1 , wherein the dry weight ratio of clay pigment to SBR binder in the water vapor barrier layer is between 100:40 and 100:70. 
     
     
         8 . The coated paper of  claim 1 , wherein the particle size distribution (%<2 μm) of said clay pigment is above 95. 
     
     
         9 . A sack comprising a ply formed from the coated paper of  claim 1 . 
     
     
         10 . The sack of  claim 9 , wherein the sack comprises at least two plies and the ply formed from the coated paper is an outer ply. 
     
     
         11 . The sack of  claim 10 , wherein the sack comprises an inner ply formed from a kraft paper having a Gurley permeance measured according to ISO 5636-5:2013 of 2-10 s. 
     
     
         12 . The sack of  claim 11 , wherein the kraft paper of the inner ply has a grammage according to ISO 536:2019 of 60-90 g/m 2 . 
     
     
         13 . The sack of  claim 10 , wherein the coated paper has a grammage according to ISO 536:2019 of 75-105 g/m 2 . 
     
     
         14 . The sack of  claim 10 , wherein the paper substrate of the coated paper has a grammage according to ISO 536:2019 of 60-90 g/m 2 . 
     
     
         15 . The coated paper of  claim 1 , wherein the shape factor of said clay pigment is below 10. 
     
     
         16 . The coated paper of  claim 3 , wherein the grammage according to ISO 536:2019 of the coated paper is 75-115 g/m 2 . 
     
     
         17 . The coated paper of  claim 1 , wherein the coat weight of the pre-coating layer is 5-10 g/m 2  and the coat weight of the water vapor barrier coating layer is 5-10 g/m 2 . 
     
     
         18 . The coated paper of  claim 6 , wherein the dry weight ratio of inorganic filler to binder in the pre-coating layer is between 100:16 and 100:8. 
     
     
         19 . The coated paper of  claim 7 , wherein the dry weight ratio of clay pigment to SBR binder in the water vapor barrier layer is between 100:40 and 100:60. 
     
     
         20 . The sack of  claim 11 , wherein the sack comprises an inner ply formed from a kraft paper having a Gurley permeance measured according to ISO 5636-5:2013 of 5-6 s.