Solvent Borne Polyurethane Composition

Abstract

A solvent borne polyurethane composition with a polymodal molecular weight distribution comprising: i) 10 to 90 wt % of at least a polyurethane A with a Mw in the range of from 4,000 up to 25,000 g/mol, ii) 90 to 10 wt % of at least a polyurethane B with a Mw in the range of from 25,000 to 100,000 g/mol and iii) a liquid medium.

1 .- 20 . (canceled) 
   
   
       21 . A solvent borne polyurethane composition comprising:
 I) 10 to 90 wt % of at least a non-film-forming polyurethane A with a weight average molecular weight (Mw) in the range of from 5,000 to 23,000 g/mol;   II) 90 to 10 wt % of at least a film-forming polyurethane B with a weight average molecular weight (Mw) in the range of from 25,000 to 100,000 g mol; where i)+ii) add up to 100%; and   III) a liquid medium.   
   
   
       22 . A solvent borne polyurethane composition according to  claim 21  wherein the polyurethanes in the composition have a polymodal molecular weight distribution. 
   
   
       23 . A solvent borne polyurethane composition according to  claim 21  having a viscosity of <10,000 mPa-s at any solids content in the range of from 20 to 75 wt % in a solvent comprising >70 wt % of at least one solvent having an evaporation rate >1. 
   
   
       24 . A solvent borne polyurethane composition according to  claim 21  wherein 15 to 85 wt % of the polyurethanes in the composition have a Mw at least 10,000 g/mol greater than the Mw of the remaining 85 to 15 wt % of the polyurethanes. 
   
   
       25 . A solvent borne polyurethane composition according to  claim 21  with the proviso that 35 to 70 wt % of polyurethanes in the composition have a Mw of at least 5,000 g/mol greater than the Mw of 20 to 50 wt % of the polyurethanes in the composition. 
   
   
       26 . A solvent borne polyurethane composition according to  claim 21  wherein the Mp is in the range of from 6,000 to 60,000 g/mol. 
   
   
       27 . A solvent borne polyurethane composition according to  claim 21  wherein the PDi is in the range of from 1.3 to 10. 
   
   
       28 . A solvent borne polyurethane composition according to  claim 21  where the Mp is in the range of from 6,000 to 60,000 g/mol and the PDi is in the range of from 2.8 to 6. 
   
   
       29 . A solvent borne polyurethane composition according to  claim 21  where polyurethane A is obtained by reacting components comprising:
 (i) 8 to 45 wt % of at least one polyisocyanate;   (ii) 0 to 5 wt % of at least one isocyanate-reactive polyol with a weight-average molecular weight in the range of from 50 to 200 g/mol;   (iii) 40 to 92 wt % of at least one isocyanate-reactive polyol with a weight-average molecular weight in the range of from 201 to 20,000 g/mol;   (iv) 0 to 9 wt % of a chain-extending and/or chain-terminating component not comprised by (i), (ii), or (iii);   (v) 0 to 3 wt % of an isocyanate-reactive polyol not comprised by (ii), (iii) or (iv);   where (i), (ii), (iii), (iv) and   (v) add up to 100%; optionally in the presence of a liquid medium.   
   
   
       30 . A solvent borne polyurethane composition according to any one of the preceding claims where polyurethane B is obtained by reacting components comprising;
 (i) 10 to 20 wt % of at least one polyisocyanate;   (ii) 0 to 3 wt % of at least one isocyanate-reactive polyol with a weight-average molecular weight in the range of from 84 to 200 g/mol;   (iii) 70 to 89 wt % of at least one isocyanate-reactive polyol with a weight-average molecular weight in the range of from 350 to 5,000 g/mol;   (iv) 3 to 8 wt % of a chain-extending and/or chain-terminating component not comprised by (i), (ii), or (iii);   (v) 0 to 3 wt % of an isocyanate-reactive polyol not comprised by (ii), (iii) or (iv);   where (i), (ii), (iii), (iv) and (v) add up to 100%;   optionally in the presence of a liquid medium.   
   
   
       31 . A process for obtaining a solvent borne polyurethane composition according to  claim 21  comprising a blend of polyurethane A and polyurethane B. 
   
   
       32 . A process for obtaining a solvent borne polyurethane composition according to  claim 30  comprising the following steps:
 1) preparing an isocyanate-terminated prepolymer;   2a) reacting the isocyanate groups of isocyanate-terminated prepolymer with 0.1 to 0.6 stoichiometric equivalents of at least one active-hydrogen containing chain-terminating compound;   2b) reacting the isocyanate groups of the isocyanate-terminated prepolymer obtained in step 2a) with 0.1 to 1.2 stoichiometric equivalents of at least one active-hydrogen containing chain-extending compound;   2c) optionally reacting the isocyanate groups obtained from step 2b) with 0 to 1.0 stoichiometric equivalents of at least one active-hydrogen-chain-terminating compound.   
   
   
       33 . A process for obtaining a solvent borne polyurethane composition according to  claim 30  comprising the following steps:
 1) preparing an isocyanate-terminated prepolymer A;   2a) reacting the isocyanate groups of isocyanate-terminated prepolymer A with 0 to 0.95 stoichiometric equivalents of at least one active-hydrogen containing chain-terminating compound;   2b) reacting the isocyanate groups of isocyanate-terminated prepolymer A with 0 to 0.95 stoichiometric equivalents of at least one active-hydrogen containing chain-extending compound; where steps 2a) and 2b) together are in the range of from 0.1 to 1.8 stoichiometric equivalents;   3) optionally introducing an isocyanate-terminated compound B;   4a) reacting the isocyanate groups of the isocyanate-terminated prepolymer obtained in steps 2a) and 2b) and isocyanate groups of the isocyanate-terminated compound B introduced in step 3) with 0 to 1.0 stoichiometric equivalents of at least one active-hydrogen containing chain-terminating compound;   4b) reacting the isocyanate groups of the isocyanate-terminated prepolymer obtained in steps 2a) and 2b) and the isocyanate groups of the isocyanate-terminated compound B introduced in step 3) with 0 to 1.2 stoichiometric equivalents of at least one active-hydrogen containing chain-extending compound;   where steps 4a) and 4b) together are in the range of from 0 to 1.2 stoichiometric equivalents;   where the process comprises at least one step with an active-hydrogen containing chain-extending compound and at least one step with an active-hydrogen containing chain-terminating compound;   where if 0 wt % of the isocyanate-terminated compound B is introduced then step 2a) comprises 0.1 to 0.95 stoichiometric equivalents of at least one active-hydrogen containing chain-terminating compound and at least a step 2a) is performed before a step 2b).   
   
   
       34 . An ink comprising a solvent borne polyurethane composition according to  claim 21 , a colorant, and optionally an additional organic solvent. 
   
   
       35 . An ink according to  claim 34  having a viscosity in the range of from 10 to 100 seconds when measured using a Ford Cup 4 at 20° C. 
   
   
       36 . A process for printing an image on a substrate comprising applying an ink according to  claim 34 . 
   
   
       37 . Use of a solvent borne polyurethane composition according to  claim 21  in a flexographic printing process. 
   
   
       38 . Use of a solvent borne polyurethane composition according to  claim 21  in a gravure printing processes. 
   
   
       39 . A laminate comprising a substrate printed with a solvent borne polyurethane composition according to  claim 21 .