Barrier paper

Abstract

The present invention relates to a barrier paper comprising at least a base paper, at least one coating colour layer S1 applied directly or indirectly to the base paper, at least one barrier layer B1 applied directly or indirectly to the coating colour layer S1, a coating B2 applied directly or indirectly to the barrier layer B1.

1 . A barrier paper comprising at least
 a base paper,   at least one coating colour layer S1 applied directly or indirectly to the base paper,   at least one barrier layer B1 applied directly or indirectly to the coating colour layer S1,   a coating B2 applied directly or indirectly to the barrier layer B1.   
     
     
         2 . The barrier paper according to  claim 1 ,
 characterized in that the coating colour layer S1 has at least one of the following properties:
 water vapour barrier, 
 oxygen barrier, 
 mineral oil barrier, 
 aroma barrier, 
 grease barrier, 
 buckling resistance of at least one property, 
 grease resistance, 
 sealability, 
 Bekk smoothness of at least 200 Bekk seconds. 
   
     
     
         3 . The barrier paper according to  claim 1 ,
 characterized in that the coating colour layer S1 comprises or consists of at least one water-soluble polymer and/or at least one water-dispersible polymer.   
     
     
         4 . The barrier paper according to  claim 3 ,
 characterized in that   the at least one water-soluble polymer and/or the at least one water-dispersible polymer is selected from the group consisting of:
 polyvinyl alcohol, in particular partially saponified or fully saponified; 
 polyvinyl alcohol copolymer, in particular copolymerized with ethylene, polyvinyl amine, acrylic acid derivatives, partially saponified or fully saponified; 
 modified fully or partially saponified polyvinyl alcohols or copolymers, in particular modifications with acyl, alkyl, acrylamide, silanol, diacetone, acetoacetyl, itaconic acid; 
 polymer with an onset temperature of less than 210° C. as determined by DSC, wherein the onset temperature is determined by DSC according to DIN EN ISO 11357-1:2010-03 as the intersection of the extrapolated baseline and the inflection tangent at the beginning of the melting or crystallization peak; 
 acrylic-based polymers; 
 polyester-based polymers; 
 nitrocellulose-based polymers; 
 polyvinyl acetate-based polymers. 
   
     
     
         5 . The barrier paper according to  claim 3 ,
 characterized in that the at least one water-soluble polymer and/or the at least one water-dispersible polymer comprise an at least partially saponified polyvinyl alcohol and/or an at least partially saponified polyvinyl alcohol copolymer, each with an onset temperature of less than 210° C. as determined by DSC.   
     
     
         6 . The barrier paper according to at  claim 3 ,
 characterized in that the at least one water-soluble polymer and/or the at least one water-dispersible polymer comprise a partially saponified polyvinyl alcohol with a degree of saponification of 30% to 95%, an average molecular weight of more than 0 and less than 100,000 g/mol, and with an onset temperature of less than 200° C. as determined by DSC.   
     
     
         7 . The barrier paper according to  claim 3 ,
 characterized in that the at least one water-soluble polymer and/or the at least one water-dispersible polymer comprise a partially saponified polyvinyl alcohol with a degree of saponification of greater than 95% to 100%, an average molecular weight of more than 70,000 g/mol, and with an onset temperature of less than 200° C. as determined by DSC.   
     
     
         8 . The barrier paper according to  claim 3 ,
 characterized in that the at least one water-soluble polymer and/or the at least one water-dispersible polymer comprise a partially saponified polyvinyl alcohol copolymer, preferably a partially saponified polyethylene vinyl alcohol, with a degree of saponification of 95% to 100%, an average molecular weight of more than 60000 g/mol, and with an onset temperature of less than 210° C. as determined by DSC.   
     
     
         9 . The barrier paper according to  claim 3 ,
 characterized in that the partially saponified polyvinyl alcohol and/or the partially saponified polyvinyl alcohol copolymer have a viscosity of less than 30 mPas at a dry content of 4%, particularly preferably less than 20 mPas and most particularly preferably less than 15 mPas.   
     
     
         10 . A barrier paper.
 characterized in that the at least one water-soluble polymer and/or the at least one water-dispersible polymer comprises a mixture of the polymers defined in  3 .   
     
     
         11 . The barrier paper according to  claim 1 ,
 characterized in that the coating colour layer S1 has a surface tension in the range of 25 to 80 mN/m, in particular 25 to 75 mN/m.   
     
     
         12 . The barrier paper according,  claim 1 ,
 characterized in that the barrier layer B1 comprises or consists of metals, in particular Al, Cu, Sn, Zn, Ag, Au, Ti, In, Si, metal alloys, metal oxides, in particular Al 2 O 3 , SiO 2 , mixed oxides or a combination thereof.   
     
     
         13 . The barrier paper according to  claim 1 ,
 characterized in that the barrier layer B1 is applied by vacuum deposition.   
     
     
         14 . The barrier paper according to  claim 1 ,
 characterized in that the barrier layer B1 has at least one of the following features:   a) optical density≥1.5 and ≤6.0,   b) layer thickness≥5 nm, preferably ≥10 nm, particularly preferably ≥15 nm, especially 5 nm to 150 nm   
     
     
         15 . The barrier paper according to  claim 1 ,
 characterized in that the coating B2 comprises or consists of at least one polymer, in particular a polymer selected from the group comprising   a) polyethylene acrylic acid copolymers,   B) polyolefins,   c) polyvinyl alcohols,   d) cellulose nitrates,   e) bio-based polymers   f) non-biobased polymers   g) styrene-butadiene latices,   h) acrylate latices.   
     
     
         16 . The barrier paper according to  claim 1 ,
 characterized in that the coating B2 has at least one of the following properties:   a) protection of barrier layer B1 against external influences, in particular mechanical or chemical influences,   b) sealable, in particular hot, ultrasonic, and cold sealable,   c) grease resistance,   d) water resistance,   e) moisture resistance,   f) printability,   g) additional barrier property.   
     
     
         17 . The barrier paper according to  claim 1 ,
 characterized in that the barrier paper has at least one of the following features:   a) WVTR≤5 g/m2/d at 23° C. and 50% relative humidity,   b) WVTR inside fold≤5 g/m2/d at 23° C. and 50% relative humidity,   c) WVTR outside fold≤5 g/m2/d at 23° C. and 50% relative humidity,   d) WVTR≤15 g/m2/d at 38° C. and 90% relative humidity,   e) WVTR inside fold≤15 g/m2/d at 38° C. and 90% relative humidity,   f) WVTR outside fold≤15 g/m2/d at 38° C. and 90% relative humidity,   g) OTR≤10 g/m 2 /d at 23° C. and 50% relative humidity,   h) OTR inside fold≤10 g/m2/d at 23° C. and 50% relative humidity,   i) OTR outside fold≤10 g/m2/d at 23° C. and 50% relative humidity,   j) buckling resistance of at least one barrier property, especially in the area of the inside fold and/or the outside fold,   k) residual moisture content of at least 2.5% (w/w), in particular at least 3.0% (w/w) based on the total weight of the barrier paper.   
     
     
         18 . The barrier paper according to  claim 1 ,
 characterized in that the coating colour layer S1, the barrier coating B1 and the coating B2 are removable in the waste paper cycle.   
     
     
         19 . The barrier paper according to  claim 18 ,
 characterized in that the barrier paper after reprocessing according to INGEDE method 11 achieves the following scores according to the Assessment of Printed Product Recyclability, Deinkability Score:   a) Luminosity Y maximum of 35 points,   b) Colour coefficient a* in the CIELAB system maximum of 20 points,   c) Dirt specks A in the two different size classes A50 maximum of 15 points and A250 maximum of 10 points,   d) Degree of dye elimination (ink elimination) IE maximum of 10 points, and   e) Filtrate darkening ΔY maximum of 10 points,   wherein the sum of all points is in the range from 0 to 100, preferably in the range from 51 to 70, more preferably in the range from 71 to 100, and/or preferably no individual point value is negative.   
     
     
         20 . The barrier paper according to  claim 1 ,
 characterized in that a precoat comprising at least one inorganic pigment and a polymeric binder is present between the base paper and the coating colour layer S1, wherein the inorganic pigment is preferably platelet-shaped and preferably comprises a talc, a precipitated calcium carbonate, a silicate, preferably a phyllosilicate or kaolin, and/or the polymeric binder comprises a polymeric binder based on a polyacrylate or styrene-butadiene.   
     
     
         21 . The barrier paper according to  claim 1 , characterized in that the basis weight of the coating colour layer S1 and of the coating B2 is in the range from 4 to 20 g/m 2 , preferably from 4 to 15 g/m 2 , based on the dried end product (air dry). 
     
     
         22 . The barrier paper according to  claim 1 ,
 characterized in that the barrier paper is free of halogenated organic compounds.   
     
     
         23 . The barrier paper according to  claim 1 ,
 characterized in that the base paper has a basis weight of 20 to 120 g/m 2 , preferably 40 to 100 g/m 2 .   
     
     
         24 . The barrier paper according to  claim 1 ,
 characterized in that the base paper has a long fibre content of 10 to 80% and a short fibre content of 20 to 90% (w/w), wherein a long fibre is a fibre with a fibre length of 2.6 to 4.4 mm, and a short fibre is a fibre with a fibre length of 0.7 to 2.2 mm.   
     
     
         25 . The barrier paper according to  claim 1 ,
 characterized in that the base paper comprises up to 90% recycled fibres.   
     
     
         26 . The barrier paper according to  claim 1 ,
 characterized in that the values for the loss factors tan Delta measured as a function of the temperature by means of dynamic mechanical thermal analysis (DMTA) of the barrier paper pass through a maximum at the temperature Tg and a first inflection point at the temperature Tw with increasing temperature.   
     
     
         27 . The barrier paper according to  claim 26 , characterized in that the temperature Tg is lower than the temperature Tw. 
     
     
         28 . The barrier paper according to  claim 26 ,
 characterized in that the amount of the difference between tan delta at the temperature Tg and tan delta at the temperature Tw is >0.013, preferably >0.014 and particularly preferably >0.015.   
     
     
         29 . A method for producing a barrier paper according to  claim 1 ,
 characterized in that an aqueous suspension comprising the starting materials of the coating colour layer is applied to the base paper, wherein the aqueous coating suspension has a solids content of 5 to 50 wt %, preferably 10 to 30 wt %, and is applied by a curtain coating process, preferably by a double curtain coating process with an operating speed of the coating plant of at least 200 m/min.   
     
     
         30 . (canceled) 
     
     
         31 . A package comprising a barrier paper according to  claim 1 , wherein the package is preferably a cold-sealed package, a heat-sealed package, an ultrasonically sealed package, in particular a tubular bag package.