Adhesive Propylene Polymer Composition Suitable for Extrusion Coating of Paper Substrates

Abstract

Two-component adhesion composition suitable for extrusion coating paper substrates which comprises a) from 70 to 98 wt % of high melt strength polypropylene (A) with a branching index g′ of 0.9 or less and b) from 2 to 30 wt % of a component (B) selected from the group of (i) maleic anhydride-modified polypropylene (MAPP) (ii) maleic anhydride-modified polypropylene wax (iii) polypropylene homopolymer with high melt flow rate or (iv) ethylene-vinyl acetate-based hot melt adhesive and its use.

1 . Two-component adhesion composition suitable for extrusion coating paper substrates comprising 
 a) from 70 to 98 wt % of high melt strength polypropylene (A) with a branching index g′ of 0.9 or less, wherein the cross-linked fraction of the polypropylene (A) does not exceed 1.0 wt.-%, determined as the relative amount of polymer insoluble in boiling xylene (xylene hot insoluble fraction, XHI) and    b) from 2 to 30 wt % of a component (B) selected from the group of    (i) maleic anhydride-modified polypropylene (MAPP) or    (ii) maleic anhydride-modified polypropylene wax.    
     
     
         2 . Composition according to  claim 1 , wherein the high melt strength polypropylene (A) is a propylene homopolymer.  
     
     
         3 . Composition according to  claim 1 , wherein the high melt strength polypropylene (A) has been obtained by treating an unmodified polypropylene (A′) with a peroxide and optionally with a bifunctional monomer.  
     
     
         4 . Composition according to  claim 1 , wherein the maleic anhydride-modified polypropylene (i) is a random copolymer of propylene and ethylene.  
     
     
         5 . Composition according to  claim 1 , wherein the maleic anhydride-modified polypropylene (i) has a content of maleic anhydride in the modified polypropylene in the range of 0.001 to 10 wt %, based on the weight of the modified polypropylene.  
     
     
         6 . Composition according to  claim 1 , wherein the maleic anhydride-modified polypropylene wax (ii) has been obtained by grafting an unmodified polypropylene wax, which was prepared in the presence of a metallocene catalyst.  
     
     
         7 . Composition according to  claim 1 , wherein the maleic anhydride-modified polypropylene wax (ii) has been obtained by grafting an unmodified polypropylene wax, which had a weight average molecular weight (Mw) of the polypropylene waxes of less than 10,000 g/mol.  
     
     
         8 . Composition according to  claim 1 , wherein the maleic anhydride-modified polypropylene wax (ii) has a content of maleic anhydride in the modified polypropylene wax in the range of 0.1 to 20 wt % based on the weight of the modified polypropylene.  
     
     
         9 . (canceled)  
     
     
         10 . (canceled)  
     
     
         11 . (canceled)  
     
     
         12 . (canceled)  
     
     
         13 . Extrusion coating process using paper as substrate and using the polypropylene composition according to  claim 1 .  
     
     
         14 . Extrusion coated article comprising a paper substrate and at least one layer of the propylene polymer composition according to  claim 1  on at least one surface of the article.  
     
     
         15 . An article according to  claim 14  which is a packaging material.  
     
     
         16 . Composition according to  claim 2 , wherein the high melt strength polypropylene (A) has been obtained by treating an unmodified polypropylene (A′) with a peroxide and optionally with a bifunctional monomer.  
     
     
         17 . Two-component adhesion composition suitable for extrusion coating paper substrates comprising 
 a) from 70 to 98 wt % of high melt strength polypropylene (A) with a branching index g′ of 0.9 or less and    b) from 2 to 30 wt % of a component (B) selected from the group of    (iii) polypropylene homopolymer with high melt flow rate or    (iv) ethylene-vinyl acetate-based hot melt adhesive.    
     
     
         18 . Composition according to  claim 17 , wherein the high melt strength polypropylene (A) is a propylene homopolymer.  
     
     
         19 . Composition according to  claim 17 , wherein the high melt flow rate polypropylene homopolymer (iii) has a melt flow rate measured according to ISO 1133 at 230° C. under a load of 2.16 kg of from 50 to 3000 g/10 min.  
     
     
         20 . Composition according to  claim 17 , wherein the high melt flow rate polypropylene homopolymer (iii) has been obtained by a controlled rheology technology using organic peroxides.  
     
     
         21 . Composition according to  claim 17 , wherein the ethylene-vinyl acetate-based hot melt adhesive (iv) contains ethylene-vinyl acetate-copolymers with 15 to 45 wt % vinyl acetate and having a melt index (ISO 1133, 190° C., 2.16 kg) in the range of 2 to 2500 g/10 min.  
     
     
         22 . Extrusion coating process using paper as substrate and using the polypropylene composition according to  claim 17 .  
     
     
         23 . Extrusion coated article comprising a paper substrate and at least one layer of the propylene polymer composition according to  claim 17  on at least one surface of the article.  
     
     
         24 . An article according to  claim 23  which is a packaging material.  
     
     
         25 . Composition according to  claim 17 , wherein the maleic anhydride-modified polypropylene (i) is a random copolymer of propylene and ethylene.