Non-woven fabric composites from lignin-rich, large diameter natural fibers

Abstract

A non-woven fabric composite containing natural fibers and a method for producing such composites. The non-woven fabric composite is comprised of large diameter, lignin-rich natural fibers with a high viscous flow temperature and a high degradation temperature combined with fibers made of a thermoplastic polymer with a lower viscous flow temperature such as polypropylene, polyethylene or a biodegradable thermoplastic polymer fiber such as polylactic acid, or mixture thereof. A hot-pressed non-woven fabric composite material prepared from the non-woven fabric composite.

1 . A non-woven fabric composite material comprising:
 a natural fiber and a fiber made from a synthetic thermoplastic polymer, wherein the natural fiber and the fiber made from a synthetic thermoplastic polymer are matted together and wherein the natural fiber has a higher viscous flow temperature and a higher degradation temperature than that of the fiber made from the synthetic thermoplastic polymer.   
   
   
       2 . The non-woven fabric composite material of  claim 1 , wherein the natural fiber has been mixed with a polyester fiber. 
   
   
       3 . The non-woven fabric composite material of  claim 1 , wherein the length of the natural fiber and the fiber made from the synthetic thermoplastic polymer is from about 25 mm to about 75 mm. 
   
   
       4 . The non-woven fabric composite material of  claim 1 , wherein the diameter of the natural fiber is from about 150 μm to about 500 μm. 
   
   
       5 . The non-woven fabric composite material of  claim 1 , wherein the natural fiber and the fiber made from the synthetic thermoplastic are matted together using carding and needle punching, cyclone air deposition, chemical, heat, or solvent treatment. 
   
   
       6 . The non-woven fabric composite material of  claim 1 , wherein the natural fiber has a lignin content of about 33 wt. %. 
   
   
       7 . The non-woven fabric composite material of  claim 1 , wherein the natural fiber is coir. 
   
   
       8 . The non-woven fabric composite material of  claim 1 , wherein the synthetic thermoplastic polymer is polypropylene, polyethylene, polylactic acid, or a mixture thereof. 
   
   
       9 . The non-woven fabric composite material of  claim 1 , wherein the synthetic thermoplastic polymer is polypropylene. 
   
   
       10 . The non-woven fabric composite material of  claim 1 , wherein the weight ratio of the natural fiber to the fiber made from the synthetic thermoplastic is from about 95:5 to about 20:80. 
   
   
       11 . A non-woven fabric composite material comprising:
 a coir fiber and a fiber made from a synthetic thermoplastic polymer,   wherein:   the coir fiber and the fiber made from the synthetic thermoplastic polymer are matted together;   the coir fiber has a diameter of from about 150 μm to about 500 μm, and a length of from about 25 mm to about 75 mm; and   the fiber made from a synthetic thermoplastic polymer is a polyethylene, polypropylene, polylactic acid, or mixture thereof having a diameter of from about 30 μm to about 50 μm, and a length of from about 25 mm to about 75 mm.   
   
   
       12 . A hot-pressed non-woven fabric composite material comprising:
 a natural fiber and a fiber made from a synthetic thermoplastic polymer, wherein the natural fiber and the fiber made from a synthetic thermoplastic polymer are matted together and hot-pressed, and wherein the natural fiber has a higher viscous flow temperature and a higher degradation temperature than that of the fiber made from the synthetic thermoplastic polymer.   
   
   
       13 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the length of the natural fiber and the fiber made from the synthetic thermoplastic polymer is from about 25 mm to about 75 mm. 
   
   
       14 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the diameter of the natural fiber is from about 150 μm to about 500 μm. 
   
   
       15 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the natural fiber has a lignin content of about 33 wt. %. 
   
   
       16 . The non-woven fabric composite material of  claim 12 , wherein the natural fiber is coir. 
   
   
       17 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the natural fiber is coir. 
   
   
       18 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the synthetic thermoplastic polymer is polypropylene, polyethylene, polylactic acid, or a mixture thereof. 
   
   
       19 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the synthetic thermoplastic polymer is polypropylene. 
   
   
       20 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the weight ratio of the natural fiber to the fiber made from the synthetic thermoplastic is from about 95:5, to about 20:80. 
   
   
       21 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the matted natural fiber and the fiber made from the synthetic thermoplastic is hot pressed at a temperature ranging from about 180° C. to about 240° C. and above. 
   
   
       22 . The hot-pressed non-woven fabric composite material of  claim 12 , wherein the matted natural fiber and the fiber made from the synthetic thermoplastic is hot pressed at a pressure ranging from about 25 psi to about 400 psi and above. 
   
   
       23 . A hot-pressed non-woven fabric composite material comprising:
 a coir fiber and a fiber made from a synthetic thermoplastic polymer,   wherein:   the coir fiber and the fiber made from the synthetic thermoplastic polymer are matted together and hot pressed;   the coir fiber has a diameter of from about 150 μm to about 500 μm, and a length of from about 25 μm to about 75 μm; and   the fiber made from a synthetic thermoplastic polymer is a polyethylene, polypropylene, or polylactic acid, having a diameter of from about 30 μm to about 50 μm, and a length of from about 25 μm to about 75 μm.   
   
   
       24 . A method of preparing a non-woven fabric composite material comprising:
 obtaining a natural fiber, with a sufficiently high viscous flow temperature and degradation temperature, having a suitable combination of stiffness, strength, and ductility;   milling the higher melting point natural fiber to a desired fiber length;   mixing the milled natural fiber with a thermoplastic fiber, wherein the thermoplastic fiber has been cut to similar lengths as those of natural fiber, and wherein the thermoplastic fiber has a lower viscous flow temperature than the viscous flow temperature and the degradation temperature of the natural fiber;   creating a matted or felted material from the blended fibers using carding and needle punching, air deposition of fibers sprayed with a light glue, or other processes, to give a matted non-woven fabric composite material.   
   
   
       25 . The method of  claim 24 , wherein the natural fiber is stripped of its waxy coating and the natural fiber or the thermoplastic fiber is treated with a chemical compatibilizer to yield a graft copolymer. 
   
   
       26 . The method of  claim 24  wherein the natural fiber has been mixed with a polyester fiber. 
   
   
       27 . A method of preparing a hot-pressed non-woven fabric composite material:
 heat pressing the matted non-woven fabric composite material of  claim 24  using a die in a compression molding machine under a suitable temperature whereby the non-woven fabric composite becomes a rigid part that has the shape of the die.