Method for making fibres

Abstract

This invention relates to a method for making fibres, the method comprising: providing a spinning dope comprising lignin and an additive polymer dissolved in a dope solvent, wherein the dope solvent comprises an ionic liquid and water; and extruding the spinning dope into a coagulation bath to obtain one or more fibres.

1 . A method for making fibres, the method comprising:
 providing a spinning dope comprising a dope solvent, lignin dissolved in the dope solvent and an additive polymer dissolved in the dope solvent, wherein the dope solvent comprises an ionic liquid and water; and   extruding the spinning dope into a coagulant to obtain one or more fibres.   
     
     
         2 . The method of  claim 1 , wherein the water content in the dope solvent is at least 5 wt %, for example 5-40 wt %, preferably 10-40 wt %, more preferably 20-40 wt %. 
     
     
         3 . The method of  claim 1 , wherein the spinning dope has a total loading of lignin and additive polymer of 6-60 wt %, 6-50 wt %, 6-40 wt %, 6-30 wt %, 8-23 wt %, 11-20 wt %, 10-20 wt %, 15-20 wt %, relative to the mass of mass of spinning dope, excluding the mass of lignin and additive polymer. 
     
     
         4 . The method of  claim 1 , wherein the weight ratio of lignin to additive polymer in the spinning dope is at least 2:1 or at least 3:1, for example from 2:1 to 10:1, preferably from 3:1 to 9:1. 
     
     
         5 . The method of  claim 1 , wherein lignin is present in the spinning dope at a loading of at least 5 wt %, relative to the total mass of dope solvent, preferably at a loading of 5-50 wt %, 5-40 wt %, 5-30 wt % or 5-15 wt %, relative to the mass of the total mass of dope solvent. 
     
     
         6 . The method of  claim 1 , wherein the additive polymer loading is present in the spinning dope at a loading of 1-10 wt %, preferably 1-5 wt %, relative to the mass of spinning dope, excluding the mass of lignin and additive polymer. 
     
     
         7 . The method of  claim 1 , wherein the additive polymer is selected from poly(vinyl alcohol) (PVA), polyvinyl acetate, polyfurfuryl alcohol, polyacrylic acid, polyethylene oxide, polyethylene imine, poly(2-hydroxyethyl methacrylate), polyoxymethylene and mixtures thereof. 
     
     
         8 . The method of  claim 7 , wherein the polymer is PVA. 
     
     
         9 . The method of  claim 8 , wherein the PVA is partially hydrolysed, having a degree of hydrolysis (DH) of 80-95%, preferably 85-90%, more preferably 86.7-88.7% hydrolysed. 
     
     
         10 . The method of  claim 1 , wherein the weight average molecular weight (Mw) of the additive polymer is from 60 to 200 kDa, preferably 80 to 190 kDa. 
     
     
         11 . The method of  claim 1 , wherein the ionic liquid comprises a cation and an anion selected from C 1-20  alkyl sulfate ([AlkylSO 4 ] − ), C 1-20  alkylsulfonate ([AlkylSO 3 ] − ), hydrogen sulfate ([HSO 4 ] − ), hydrogen sulfite ([HSO 3 ] − ), dihydrogen phosphate ([H 2 PO 4 ] − ), hydrogen phosphate ([HPO 4]   2− ), chloride (Cl − ), bromide (Br − ), trifluoromethanesulfonate ([OTf] − ), formate ([HCOO] − ) and acetate ([MeCO 2 ] − ); and/or
 wherein the anion is selected from [HSO 4 ] −  and [HCOO] − ; and/or   wherein the ionic liquid comprises a cation and an anion, wherein the cation contains a nitrogen-containing heterocyclic moiety or wherein the cation is a cation of Formula I   
       
         
           
           
               
               
           
         
         wherein A 1  to A 4  are each independently selected from H, an aliphatic, C 3-6  carbocycle, C 6-10  aryl, alkylaryl, and heteroaryl; and/or 
         wherein the ionic liquid is an [alkylammonium][HSO 4 ] or [alkylammonium][HCOO] ionic liquid. 
       
     
     
         12 - 14 . (canceled) 
     
     
         15 . The method of  claim 1 , wherein the ionic liquid is triethylammonium hydrogen sulfate [TEA][HSO 4 ], N,N-dimethylbutylammonium hydrogen sulfate [DMBA][HSO 4 ], diethylammonium hydrogen sulfate [DEA][HSO 4 ], N,N-dimethylethylammonium hydrogen sulfate ([DMEA][HSO 4 ]), diethanolammonium chloride [DEtOHA]Cl, 1-methylimidazolium hydrogen chloride [HMim]Cl, 1-ethyl-3-methylimidazolium chloride [EMim]Cl, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate [EMim][OTf], 1-butylimidazolium hydrogen sulfate ([HBim][HSO 4 ]), methylbutylammonium hydrogen sulfate ([MBA][HSO 4 ]), 1-methylimidazolium formate ([HMim][HCOO]), N,N-dimethylbutylammonium formate ([DMBA][HCOO]), N,N-dimethylethylammonium hydrogen sulfate ([DMEA][HSO 4 ]), 1-butyl-3-methylimidazolium hydrogen sulfate [BMim][HSO 4 ], or N-dimethylbutylammonium acetate ([DMBA][OAc]), or a mixture thereof, preferably wherein the ionic liquid is [DMBA][HSO 4 ]. 
     
     
         16 . The method of  claim 1 , wherein the dope solvent further comprises ethanol, optionally wherein the ethanol is present at 1-20 wt %, preferably 5-15 wt %, relative to the total weight of dope solvent. 
     
     
         17 . The method of  claim 1 , wherein the coagulant comprises water; and/or
 wherein the coagulant comprises water and ionic liquid, wherein the ionic liquid is present at no more than 60 wt %, no more than 30 wt %, or no more than 15 wt %, preferably 1-60 wt %, 1-30 wt % or 1-15 wt %, more preferably 5-10 wt %, relative to the total mass of coagulant; and/or   wherein the coagulant comprises water and sodium sulfate.   
     
     
         18 - 19 . (canceled) 
     
     
         20 . The method of  claim 1 , further comprising aging the spinning dope for at least 2 minutes, preferably at least 30 minutes prior to the extruding; and/or
 further comprising drying the one or more fibres under mechanical tension; and/or   further comprising drying the one or more fibres by heating the one or more fibres in air, optionally at 150-300° C.; and/or   further comprising carbonising the one or more fibres to obtain carbon fibres, optionally wherein the carbonising comprises heating the one or more fibres to 800-3000° C., preferably 1200-1800° C., under an inert atmosphere.   
     
     
         21 . The method of  claim 1 , wherein the providing the spinning dope comprises:
 a) contacting a lignocellulosic biomass comprising lignin and cellulose with a composition comprising the ionic liquid and water (preferably 5-40 wt % water), to dissolve the lignin and produce a cellulose pulp;   b) separating the cellulose pulp to obtain a liquor comprising the ionic liquid, water and lignin; and   c) combining the liquor with the additive polymer to obtain the spinning dope.   
     
     
         22 . The method of  claim 21 , wherein the lignocellulosic biomass is contacted with the composition at 100-180° C. 
     
     
         23 - 24 . (canceled) 
     
     
         25 . The method of claim  24 , further comprising weaving the fibres to form a fabric. 
     
     
         26 . (canceled) 
     
     
         27 . A fibre obtainable by the method of  claim 1 . 
     
     
         28 . A fabric comprising one or more fibres according to  claim 27 .