Process for partial delignification and filling of a lignocellulosic material, and composite material structure able to be obtained by this process

Abstract

The invention relates to a process for treating a lignocellulosic material, e.g., wood, comprising the following steps: providing a lignocellulosic material; removing at least some but less than all lignin from the lignocellulosic material to yield a delignified structure; and densifying the delignified structure to yield the delignified, densified material, wherein the delignified, densified material is equal in size or is smaller in size relative to the lignocellulosic material provided; where densifying may include contacting said delignified structure, at least in part, with at least one fluid at a pressure greater than atmospheric pressure. The invention also relates to a composite structure able to be obtained in this way, and to any part comprising at least one such structure.

1 . A method for generating a delignified, densified material, comprising:
 (a) providing a lignocellulosic material;   (b) removing at least some but less than all lignin from the lignocellulosic material to yield a delignified structure; and   (c) densifying the delignified structure of (b) to yield the delignified, densified material, wherein the delignified, densified material is equal in size or is smaller in size relative to the lignocellulosic material provided in (a); and,   wherein densifying in (c) comprises contacting said delignified structure, at least in part, with at least one fluid.   
     
     
         2 . The method of  claim 1 , wherein the delignified, densified material comprises a three-dimensional structure of cellulose and lignin, and wherein the three-dimensional structure comprises hydrogen bonds. 
     
     
         3 . The method of  claim 1 , wherein the delignified, densified material has increased resistance to an axial compression force than the lignocellulosic material in (a). 
     
     
         4 . The method of  claim 1  wherein the removing in (b) removes at least 40% by weight and at most 85% by weight of the lignin from the lignocellulosic material. 
     
     
         5 . The method of  claim 1 , wherein the removing in (b) comprises soaking the lignocellulosic material with at least one organic fluid. 
     
     
         6 . The method of  claim 6 , wherein the at least one organic fluid comprises a polarity agent. 
     
     
         7 . The method of  claim 6 , wherein the lignocellulosic material is soaked for at least 6 hours. 
     
     
         8 . The method of  claim 1 , wherein the removing in (b) comprises soaking the lignocellulosic material with at least one aqueous fluid having an alkaline pH. 
     
     
         9 . The method of  claim 8 , wherein the soaking is performed under a vacuum. 
     
     
         10 . The method of  claim 8 , wherein the alkaline pH is about 12. 
     
     
         11 . The method of  claim 8 , wherein the at least one aqueous fluid comprises sodium hydroxide. 
     
     
         12 . The method of  claim 8 , wherein the at least one aqueous fluid comprises sodium sulfite. 
     
     
         13 . The method of  claim 8 , wherein the soaking is performed for at least 30 minutes. 
     
     
         14 . The method of  claim 8 , wherein the temperature of the at least one aqueous fluid exceeds 60° C. 
     
     
         15 . The method of  claim 8 , wherein the removing in (b) further comprises washing the lignocellulosic material at least once with water. 
     
     
         16 . The method of  claim 15  wherein the water has a temperature of at least 30° C. 
     
     
         17 . The method of  claim 8 , wherein the removing in (b) further comprises washing the lignocellulosic material at least once with an organic solution. 
     
     
         18 . The method of  claim 1 , wherein the delignified structure in (b) has a water content of from 0% to 30%. 
     
     
         19 . The method of  claim 1 , wherein the delignified structure in (b) or the delignified, densified material has improved fire resistance relative to the lignocellulosic material in (a). 
     
     
         20 . The method of  claim 1 , wherein the delignified, densified material has a density at least 5% greater than that of the lignocellulosic material in (a). 
     
     
         21 . The method of  claim 1 , wherein densifying comprises removing air from said delignified structure 
     
     
         22 . A delignified, densified material, comprising:
 (a) cellulose;   (b) hemicellulose; and   (c) lignin;   wherein the delignified, densified material is made from a natural wood; wherein at least 40% and at most 85% by weight of the lignin present in the natural wood is removed by a chemical treatment,   wherein the delignified, densified material is equal in size or is smaller in size relative to the lignocellulosic material prior to chemical treatment.   
     
     
         23 . The delignified, densified material of  claim 22 , wherein the delignified, densified material comprises a three-dimensional network of the cellulose and the lignin. 
     
     
         24 . The delignified, densified material of  claim 22 , wherein the three-dimensional structure comprises hydrogen bonds. 
     
     
         25 . The delignified, densified material of  claim 22 , wherein the delignified, densified material has a higher ductility than the natural wood. 
     
     
         26 . The delignified, densified material of  claim 22 , wherein the delignified, densified material comprises hydrogen bonds. 
     
     
         27 . The delignified, densified material of  claim 22 , wherein the lignin of the delignified, densified material is from 5.25% to 10.8% by weight of the delignified, densified material. 
     
     
         28 . The delignified, densified material of  claim 22 , wherein the delignified, densified material has (i) a maximum stress at breaking and a bending deflection greater than the natural wood as determined by a bending measurement, or (ii) a maximum stress at breaking and deformation greater than the natural wood as determined by an axial compression measurement. 
     
     
         29 . The delignified, densified material of  claim 22 , wherein the delignified, densified material is fire resistant. 
     
     
         30 . The delignified, densified material of  claim 22 , wherein the delignified, densified material comprises essentially no air.