Lignin-derived thermoplastic co-polymers and methods of preparation

Abstract

The present invention relates to a crosslinked lignin comprising a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, wherein said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100° C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. Thermoplastic copolymers containing the crosslinked lignin are also described. Methods for producing the crosslinked lignin and thermoplastic copolymers are also described.

What is claimed is: 
     
         1 . A crosslinked lignin comprising a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, wherein said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100° C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. 
     
     
         2 . The crosslinked lignin of  claim 1 , wherein said number-average molecular weight is at least 100,000 g/mol. 
     
     
         3 . The crosslinked lignin polymer of  claim 1 , wherein said number-average molecular weight is at least 150,000 g/mol. 
     
     
         4 . The crosslinked lignin polymer of  claim 1 , wherein said number-average molecular weight is at least 200,000 g/mol. 
     
     
         5 . The crosslinked lignin polymer of  claim 1 , wherein said glass transition temperature is at least 120° C. 
     
     
         6 . The crosslinked lignin polymer of  claim 1 , wherein said glass transition temperature is at least 150° C. 
     
     
         7 . The crosslinked lignin polymer of  claim 1 , wherein said glass transition temperature is at least 180° C. 
     
     
         8 . The crosslinked lignin polymer of  claim 1 , wherein said glass transition temperature is at least 200° C. 
     
     
         9 . A thermoplastic copolymer, wherein said thermoplastic copolymer has a two-phase morphology and is comprised of crosslinked lignin copolymerized with non-lignin thermoplastic polymer segments, wherein said crosslinked lignin is comprised of a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, and said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has a glass transition temperature of at least 100° C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. 
     
     
         10 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer is a block copolymer or multiphase copolymer. 
     
     
         11 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer is a graft copolymer. 
     
     
         12 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer has a glass transition temperature selected from a temperature in the range of −100° C. up to 200° C. 
     
     
         13 . The thermoplastic copolymer of  claim 9 , wherein said non-lignin thermoplastic polymer segments contain unsaturated carbon-carbon bonds. 
     
     
         14 . The thermoplastic copolymer of  claim 13 , wherein said non-lignin thermoplastic polymer segments are derived from monomer units having a chemical structure within the following generic chemical structure: 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6  are independently selected from hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, and halogen atoms. 
     
     
         15 . The thermoplastic copolymer of  claim 14 , wherein said non-lignin thermoplastic polymer segments comprise polyisoprene units. 
     
     
         16 . The thermoplastic copolymer of  claim 14 , wherein said non-lignin thermoplastic polymer segments comprise polybutadiene units. 
     
     
         17 . The thermoplastic copolymer of  claim 9 , wherein said non-lignin thermoplastic polymer segments are alkyleneoxide polymer units. 
     
     
         18 . The thermoplastic copolymer of  claim 17 , wherein said alkylene-oxide polymer units are ethyleneoxide polymer units. 
     
     
         19 . The thermoplastic copolymer of  claim 9 , wherein said non-lignin thermoplastic polymer segments possess a saturated backbone and have a chemical structure within the following generic chemical structure: 
       
         
           
           
               
               
           
         
       
       wherein R 7 , R 8 , R 9 , and R 10  are independently selected from hydrogen atom, saturated or unsaturated hydrocarbon groups having 1 to 4 carbon atoms, nitrile, halogen atoms, and groups having formulas —C(O)R 11 , C(O)OR 12 , and —OR 13 , wherein R11, R 12,  and R 13  are selected from hydrogen atom and saturated or unsaturated hydrocarbon groups having 1 to 4 carbon atoms, and n is an integer of at least 2, and said generic chemical structure can be a monomer or copolymer. 
     
     
         20 . The thermoplastic copolymer of  claim 9 , wherein said non-lignin thermoplastic polymer segments are comprised of a polyhydroxyalkanoate structure within the following generic chemical structure: 
       
         
           
           
               
               
           
         
       
       wherein R 14  is selected from a hydrogen atom or hydrocarbon group, t is an integer from 0 to 3, n is an integer of at least 5, and said generic structure can be a monomer or copolymer. 
     
     
         21 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer exhibits an angular shear rate viscosity of at least 500 Pa·s at an angular frequency of up to 1000 rad/s at room temperature. 
     
     
         22 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer exhibits an angular shear rate viscosity of at least 1000 Pa·s at an angular frequency of up to 1000 rad/s at room temperature. 
     
     
         23 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer exhibits a shear modulus of at least 100 Pa at an angular frequency of up to 10 rad/s. 
     
     
         24 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer exhibits a shear modulus of at least 1000 Pa at an angular frequency of up to 10 rad/s. 
     
     
         25 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer exhibits a shear modulus of at least 1200 Pa at an angular frequency of up to 10 rad/s. 
     
     
         26 . The thermoplastic copolymer of  claim 9 , wherein said thermoplastic copolymer contains at least 10 weight percent and up to 60 weight percent of said crosslinked lignin. 
     
     
         27 . The thermoplastic copolymer of  claim 26 , wherein said thermoplastic copolymer contains at least 15 weight percent and up to 50 weight percent of said crosslinked lignin. 
     
     
         28 . The thermoplastic copolymer of  claim 26 , wherein said thermoplastic copolymer contains at least 20 weight percent and up to 50 weight percent of said crosslinked lignin. 
     
     
         29 . A method for preparing a crosslinked lignin, the process comprising treating a precursor lignin having a number-average molecular weight of up to 10,000 g/mol with formaldehyde and/or glyoxal, present in a concentration of up to 10 wt % of reaction volume, under condensation conditions to produce said crosslinked lignin, wherein said crosslinked lignin includes methylene and/or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, wherein said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least or greater than 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100° C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. 
     
     
         30 . The method of  claim 29 , wherein said formaldehyde and/or glyoxal is present in a concentration of up to 5 wt % of reaction volume. 
     
     
         31 . The method of  claim 29 , wherein said formaldehyde and/or glyoxal is in a mole ratio to lignin phenolic groups of 1:10 to 1:100. 
     
     
         32 . The method of  claim 29 , wherein said precursor lignin has a number-average molecular weight of at least 500 g/mol. 
     
     
         33 . The method of  claim 29 , wherein said precursor lignin has a number-average molecular weight of up to 3,000 g/mol. 
     
     
         34 . A method for preparing a thermoplastic copolymer, the method comprising reacting a crosslinked lignin with non-lignin thermoplastic polymer segments containing lignin-reactive groups thereon, wherein said crosslinked lignin is comprised of a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, and said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100° C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. 
     
     
         35 . The method of  claim 34 , wherein said lignin-reactive groups are selected from carboxylic acid, carboxylic acid ester, acyl chloride, epoxy, and isocyanate groups. 
     
     
         36 . The method of  claim 34 , wherein said non-lignin thermoplastic polymer segments are derived from monomer units having a chemical structure within the following generic chemical structure: 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6  are independently selected from hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, and halogen atoms, and wherein each of said non-lignin thermoplastic polymer segments according to formula (1) includes at least two lignin-reactive groups. 
     
     
         37 . The method of  claim 36 , wherein said non-lignin thermoplastic polymer segments are comprised of polyisoprene units. 
     
     
         38 . The method of  claim 36 , wherein said non-lignin thermoplastic polymer segments are comprised of polybutadiene units. 
     
     
         39 . The method of  claim 34 , wherein said non-lignin thermoplastic polymer segments are alkyleneoxide polymer units, each containing at least two phenol-reactive groups. 
     
     
         40 . The method of  claim 34 , wherein said non-lignin thermoplastic polymer segments possess a saturated backbone and have a chemical structure within the following generic chemical structure: 
       
         
           
           
               
               
           
         
       
       wherein R 7 , R 8 , R 9 , and R 10  are independently selected from hydrogen atom, saturated or unsaturated hydrocarbon groups having 1 to 4 carbon atoms, nitrile, halogen atoms, and groups having formulas —C(O)R 11 , C(O)OR 12 , and —OR 13 , wherein R11, R 12,  and R 13  are selected from hydrogen atom and saturated or unsaturated hydrocarbon groups having 1 to 4 carbon atoms, and n is an integer of at least 2, wherein said generic chemical structure can be a monomer or copolymer and includes at least two lignin-reactive groups. 
     
     
         41 . The method of  claim 34 , wherein said non-lignin thermoplastic polymer segments are comprised of polyhydroxyalkanoate structure within the following generic chemical structure: 
       
         
           
           
               
               
           
         
       
       wherein R 14  is selected from a hydrogen atom or hydrocarbon group, t is an integer from 0 to 3, n is an integer of at least 5, and said generic structure can be a monomer or copolymer and includes at least two lignin-reactive groups. 
     
     
         42 . The method of  claim 34 , wherein said thermoplastic copolymer exhibits an angular shear rate viscosity of at least 500 Pa·s at an angular frequency of up to 1000 rad/s at room temperature. 
     
     
         43 . The method of  claim 34 , wherein said thermoplastic copolymer exhibits a shear modulus of at least 100 Pa at an angular frequency of up to 10 rad/s. 
     
     
         44 . The method of  claim 34 , wherein said thermoplastic copolymer contains at least 10 weight percent and up to 50 weight percent of said crosslinked lignin. 
     
     
         45 . The method of  claim 34 , wherein said crosslinked lignin and non-lignin thermoplastic polymer segments are reacted under in situ melt mixing polymerization conditions. 
     
     
         46 . The method of  claim 34 , wherein said crosslinked lignin and non-lignin thermoplastic polymer segments are reacted under free-radical grafting polymerization conditions.