Barrier paper

Abstract

The invention relates to a barrier paper comprising a base paper and at least one coating color layer S1, which is applied directly or indirectly to the base paper, the coating color layer S1 comprising at least one polymer binder and at least one wax, a method for producing such a barrier paper, the use of such a barrier paper as a packaging material and a packaging material comprising such a barrier paper.

1 . A barrier paper comprising a base paper and at least one coating color layer S1 applied directly or indirectly to the base paper, wherein the coating color layer S1 comprises at least one polymer binder and at least one wax, and wherein the coating color layer S1 has at least one of the following features:
 a) change in surface tension of not more than +10 mN/m, preferably not more than +6 mN/m,   b) change of the polar component of the surface tension of not more than −0.65 mN/m, preferably not more than −0.60 mN/m,   c) change in the polar component of the surface tension of not more than −3.0% pts, preferably not more than −1.5% pts,   wherein the respective change is determined by measuring and comparing the measured values of the surface tension and the polar component of the surface tension before and after a temperature treatment of the barrier paper at 105° C. for 3 min.   
     
     
         2 . The barrier paper according to  claim 1 , wherein the wax content of the coating color layer S1 is selected such that the barrier paper has at least one of the following features:
 a) a sealed-seam strength (cold tack) after sealing of the coating color layer S1 against the coating color layer S1 of ≥4 N/15 mm, with the heat sealing parameters sealing temperature of 130 to 150° C., sealing time of 0.3 sec, sealing pressure of 3.3 bar or with ultrasonic sealing parameters that cause a sealing temperature of 130 to 150° C. and a sealing time of 0.3 sec and a sealing pressure of 3.3 bar,   b) a water vapor transmission rate (WVTR)≤20 g/m 2 /d (38° C., 90% r.h.),   c) a water vapor transmission rate (WVTR)≤8 g/m 2 /d (23° C., 50% r.h.),   d) an increase in water vapor permeability (38° C., 90% r.h.) after carrying out the palm kernel fat test according to DIN 53116 under the test conditions (10 min exposure time and pressure load of 2000 N/m 2 ) of not more than 70 g/m 2 /d, preferably not of not more than 60 g/m 2 /d,   e) an increase in water vapor permeability after carrying out the palm kernel fat test in accordance with DIN 53116 under the test conditions (60 min exposure time and 2000 N/m 2 ) of no more than a factor of 6,   f) a static coefficient of friction (coating color layer S1 against coating color layer S1) of <0.9,   g) a kinetic coefficient of friction (coating color layer S1 against coating color layer S1) of <0.6,   wherein the values for a) to g) are determined for a basis weight of the coating color layer S1 of ≤12 g/m 2 .   
     
     
         3 . The barrier paper according to  claim 2 , characterized in that the water vapor permeability (38° C., 90% RH) has a change of at most-40%, preferably of less than −30%,
 wherein the change is determined by measuring and comparing the measured values of water vapor permeability before and after a temperature treatment of the barrier paper at 105° C. for 3 min. 
 
     
     
         4 . The barrier paper according to  any one of the preceding claims , wherein the wax is a wax as defined by DGF (DGF standard method M-I 1 (75)). 
     
     
         5 . The barrier paper according to  claim 1 , wherein the at least one wax is a wax based on mixtures or pure substances of fossil or natural short- to medium-chain hydrocarbons, their acids, esters, amides and diamides, hydrogenated vegetable oils; waxes and/or metal soaps produced by hydrogenation or partial hydrogenation of vegetable oils and animal oils or fats, preferably heneicosane, docosane, tricosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane, nonacosane, Triacontane, hentriacontane, dotriacontane, tritriacontane, tetratriacontane, pentatriacontane, hexatriacontane, heptatriacontane, octatriacontane, nonatriacontane, montan waxes, carnauba wax, beeswax, candelilla wax, rice bran wax, sugar cane wax, wax obtained from sunflower seed press cake, particularly preferably beeswax and/or wax obtained by hydrogenation of soybean oil, and/or paraffin waxes with an average molecular weight of at least 500 Daltons and a viscosity of at least 11 cSt at 100° C. 
     
     
         6 . The barrier paper according to  claim 1 , wherein the at least one wax is present therein in an amount of from 0.01 to 10% (w/w), preferably from 0.01 to <8.0% (w/w), preferably from 0.01<6.0% (w/w), more preferably from 0.01 to <5.0% (w/w), and most particularly preferably from 0.01≤2.0% (w/w), and preferably the lower limit is at least 0.1% (w/w), particularly preferably at least 0.2% (w/w) based on the total weight of the coating color layer S1. 
     
     
         7 . The barrier paper according to  claim 1 , wherein the at least one polymer binder in the coating color layer S1 is selected from the group comprising polyacrylates and copolymers with unsaturated hydrocarbons; polyolefins; copolymers consisting of unsaturated hydrocarbons and acrylic acid or salts thereof; (partially carboxylated) styrene-butadiene copolymers; styrene-butadiene copolymers; styrene-butadienes; polyvinyl acetates; partially saponified polyvinyl acetates; polyesters, such as polylactides; and polyhydroxyalkanoates (produced from glucose) polyamides; polyurethanes; polyethers; polyethyleneimines; and/or polyvinylamides; preferably selected from the group comprising polymethyl acrylates, polymethyl methacrylates, polyethylarylates, polyethyl methacrylates, poly(n-, iso-, tert.-)butyl acrylates, poly(n-, iso-, tert.-) butyl methacrylates, polycyclohexyl methacrylates, polyethylhexyl acrylates and copolymers thereof; graft polymers, and copolymers thereof with styrene, acrylonitrile, methylstyrene, and/or vinyl toluene; particularly preferably styrene acrylate/methyl acrylate/butyl acrylate/ethylhexyl acrylate copolymer, and/or natural polymers, such as (modified) polysaccharides, proteins, lignin (derivatives), and other natural macromolecules, such as, e.g. shellac. 
     
     
         8 . The barrier paper according to  claim 1 , wherein the at least one polymer binder is present in the coating color layer S1 an amount of 99.9 to >92% (w/w), preferably >94% (w/w), more preferably >95% (w/w) and most preferably >98% (w/w) based on the total weight thereof. 
     
     
         9 . The barrier paper according to  claim 1 , wherein the at least one wax is enriched in the coating color layer S1 on the side facing away from the base paper, which is indirectly detected by the fact that the change in the polar component of the surface tension does not exceed-0.65 mN/m, and/or
 the change in the polar component of the surface tension does not exceed-3.0% pts, wherein the respective change is determined by measuring and comparing the measured values of the polar component of the surface tension before and after a temperature treatment of the barrier paper at 105° C. for 3 min.   
     
     
         10 . The barrier paper according to  claim 1 , wherein the base paper has a basis weight of 20 to 120 g/m 2 , preferably 40 to 100 g/m 2 . 
     
     
         11 . The barrier paper according to  claim 1 , wherein the base paper has a long fiber content of 10 to 80% (w/w), preferably from 20 to 50% (w/w), and a short fiber content of 20 to 90% (w/w), preferably from 50 to 80% (w/w), wherein a long fiber is a fiber with a fiber length of 2.6 to 4.4 mm and a short fiber is a fiber with a fiber length of 0.7 to 2.2 mm. 
     
     
         12 . The barrier paper according to  claim 1 , wherein the base paper comprises a filler content of 0% (w/w) to 20% (w/w), preferably 0% (w/w) to 5% (w/w), of fillers, preferably excluding the value 0% (w/w), wherein the fillers comprise in particular ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), kaolin and/or talc. 
     
     
         13 . The barrier paper according to  claim 1 , wherein the barrier paper comprises at least one further coating color layer S2 applied directly or indirectly between the base paper and the coating color layer S1, in particular for forming a mineral oil and/or fat barrier layer and/or also an oxygen barrier layer, comprising at least one hydrophilic polymer. 
     
     
         14 . The barrier paper according to  claim 1 , wherein a further coating color layer S3 is present directly on the base paper, in particular a coating color layer comprising or consisting of at least one inorganic pigment and a polymer binder. 
     
     
         15 . A method for producing a barrier paper according to  claim 1 , characterized in that an aqueous suspension comprising the starting materials of the coating color layer S1 is applied indirectly or directly to the base paper, wherein the aqueous application suspension has a solids content of 15 to 55% (w/w), preferably of 20 to 45% (w/w), and is applied by a curtain coating process at an operating speed of the coating machine of at least 100 m/min and is subsequently dried, the drying preferably being carried out by means of infrared or heat emitters and a subsequent area of air hoods, and the web temperature remaining <90° C. in the entire drying area. 
     
     
         16 . A barrier paper obtained by the method according to  claim 15 . 
     
     
         17 . (canceled) 
     
     
         18 . A packaging material, in particular a heat-sealable packaging material,  claim 1 .