Barrier paper or board

Abstract

A process for improving the barrier properties of a barrier layer in a pulp-based substrate layer having a barrier layer, comprising the steps of providing a pulp-based substrate layer having a layer of an aqueous barrier composition applied to it, and then drying the pulp-based substrate layer having a layer of aqueous barrier composition applied to it to form a pulp-based substrate layer having a barrier layer, such that the moisture content of the pulp-based substrate layer having a barrier layer is below 2.5% by weight, preferably below 2% by weight, based on the weight of the pulp-based substrate layer having a barrier layer.

1 - 15 . (canceled) 
     
     
         16 . A process for improving the barrier properties of a barrier layer comprised in a pulp-based substrate layer having a barrier layer, comprising the steps of
 a) providing a pulp-based substrate layer having a layer of an aqueous barrier composition applied to it,   b) drying the pulp-based substrate layer having a layer of aqueous barrier composition applied to it to form a pulp-based substrate layer having a barrier layer, such that the moisture content of the pulp-based substrate layer having a barrier layer is below 2.5% by weight, based on the weight of the pulp-based substrate layer having a barrier layer.   
     
     
         17 . The process according to  claim 16 , wherein the pulp-based substrate layer is a paper or paperboard layer. 
     
     
         18 . The process according to  claim 16 , wherein the aqueous barrier composition comprises a barrier compound. 
     
     
         19 . The process according to  claim 16 , wherein the aqueous barrier composition comprises a moisture vapour barrier compound, an oxygen barrier compound, or both. 
     
     
         20 . The process according to  claim 16 , wherein after step b), the process further comprises the step c) of moisturizing the pulp-based substrate layer having a barrier layer, such that the moisture content of the pulp-based substrate layer having a barrier layer is 3.5% by weight or more, based on the weight of the pulp-based substrate layer having a barrier layer. 
     
     
         21 . The process according to  claim 16 , wherein the aqueous barrier composition comprises a polymer barrier compound and an inorganic barrier compound. 
     
     
         22 . The process according to  claim 16 , wherein drying the pulp-based substrate layer having a layer of aqueous barrier composition applied to it to form a pulp-based substrate layer having a barrier layer is achieved by exposing the pulp-based substrate layer having a layer of aqueous barrier composition to either heat, radiation or underpressure, or a combination of two or more thereof. 
     
     
         23 . The process according to  claim 16 , wherein drying the pulp-based substrate layer having a layer of aqueous barrier composition applied to it to form a pulp-based substrate layer having a barrier layer is achieved by heating the pulp-based substrate layer having a layer of aqueous barrier composition to a temperature of at least 100° C. 
     
     
         24 . The process according to  claim 16 , wherein in step a), the pulp-based substrate layer having a layer of an aqueous barrier composition applied to it has a primer layer positioned between the pulp-based substrate layer and the layer of the aqueous barrier composition. 
     
     
         25 . The process according to  claim 16 , wherein the process further comprises a step of applying an inorganic barrier layer or a metal barrier layer to the barrier layer via thin-film deposition. 
     
     
         26 . The process according to  claim 16 , wherein the process further comprises a step of applying an inorganic barrier layer or a metal barrier layer to the barrier layer via thin-film deposition and wherein after the step of applying an inorganic barrier layer or a metal barrier layer to the barrier layer via thin-film deposition the process further comprises a subsequent step of applying a further layer of aqueous barrier composition to the inorganic barrier layer or the metal barrier layer and drying the resulting stack of layers having the further layer of aqueous barrier composition applied to it to form a further barrier layer such that the moisture content of the resulting stack of layers having a further barrier layer is below 2.5% by weight, based on the weight of the resulting stack of layers having a further barrier layer. 
     
     
         27 . A packaging material comprising at least one pulp-based substrate layer having, in this order,
 optionally a primer layer adjacent to the pulp-based substrate layer,   a first barrier layer adjacent to the pulp-based substrate layer or the primer layer,   optionally a sealing layer such as a heat- or cold-sealing layer adjacent to the first barrier layer, wherein the amount of the first barrier layer ranges from 4 gsm to 11 gsm, and wherein the packaging material exhibits a WVTR at tropical conditions (38° C., 90% RH) of 1 to 5 g/(m 2 ·d).   
     
     
         28 . A packaging material comprising at least one pulp-based substrate layer having, in this order,
 optionally a primer layer adjacent to the pulp-based substrate layer,   a first barrier layer adjacent to the pulp-based substrate layer or the primer layer,   an inorganic barrier layer such as a metal layer adjacent to the first barrier layer, where the inorganic barrier layer is deposited via thin-film deposition,   a second barrier layer adjacent to the inorganic barrier layer,   optionally a sealing layer such as a heat- or cold-sealing layer adjacent to the second barrier layer, wherein the combined amount of the first barrier layer and the second barrier layer ranges from 4 gsm to 11 gsm, and wherein the packaging material exhibits a WVTR at tropical conditions (38° C., 90% RH) of less than 1.5 g/(m 2 ·d).   
     
     
         29 . The packaging material according to  claim 27 , wherein the packaging material is a wrapping paper or a food tray. 
     
     
         30 . A food item packaged in a packaging material according to  claim 27 . 
     
     
         31 . The process according to  claim 16 , wherein the moisture content of the pulp-based substrate layer having a barrier layer is below 2% by weight, based on the weight of the pulp-based substrate layer having a barrier layer. 
     
     
         32 . The process according to  claim 16 , wherein the aqueous barrier composition comprises a barrier compound in the form of an aqueous dispersion of a barrier compound or an aqueous solution of a barrier compound. 
     
     
         33 . The process according to  claim 16 , wherein drying the pulp-based substrate layer having a layer of aqueous barrier composition applied to it to form a pulp-based substrate layer having a barrier layer is achieved by heating the pulp-based substrate layer having a layer of aqueous barrier composition to a temperature of at least 115° C. 
     
     
         34 . The process according to  claim 16 , wherein drying the pulp-based substrate layer having a layer of aqueous barrier composition applied to it to form a pulp-based substrate layer having a barrier layer is achieved by heating the pulp-based substrate layer having a layer of aqueous barrier composition to a temperature of at least 130° C. 
     
     
         35 . The process according to  claim 26 , wherein the moisture content of the resulting stack of layers having a further barrier layer is below 2% by weight, based on the weight of the resulting stack of layers having a further barrier layer. 
     
     
         36 . The packaging material according to  claim 27 , wherein the amount of the first barrier layer ranges from 4 to 6 gsm. 
     
     
         37 . The packaging material according to  claim 28 , wherein the combined amount of the first barrier layer and the second barrier layer ranges from 9 to 11 gsm, and wherein the packaging material exhibits a WVTR at tropical conditions (38° C., 90% RH) of 0.01 to 1.0 g/(m2·d).