Fibers comprising starch and polymers

Abstract

The present invention is directed to highly attenuated fibers produced by melt spinning a composition comprising destructurized starch, a thermoplastic polymer, and a plasticizer. The present invention is also directed to highly attenuated fibers containing microfibrils which are formed within the starch matrix. Nonwoven webs and disposable articles comprising the highly attenuated fibers are also disclosed.

What is claimed is:  
     
         1 . A highly attenuated fiber produced by melt spinning a composition comprising: 
 a. destructurized starch,    b. a thermoplastic polymer, and    c. a plasticizer.    
     
     
         2 . The highly attenuated fiber of  claim 1  wherein the destructurized starch is present in an amount of from about 5% to about 85%.  
     
     
         3 . The highly attenuated fiber of  claim 1  wherein the thermoplastic polymer is present in an amount of from about 5% to about 90%.  
     
     
         4 . The highly attenuated fiber of  claim 1  wherein the plasticizer is present in an amount of from about 2% to about 70%.  
     
     
         5 . The highly attenuated fiber of  claim 1  wherein more than one thermoplastic polymer is present.  
     
     
         6 . The highly attenuated fiber of  claim 1  wherein the thermoplastic polymer is selected from the groups consisting of polypropylene, polyethylene, polyamides, polyvinyl alcohol, polyolefin copolymers, polyolefin carboxylic acid copolymers, ethylene acrylic acid, polyesters, and combinations thereof.  
     
     
         7 . The highly attenuated fiber of  claim 1  wherein the fiber has a diameter of less than 200 micrometers.  
     
     
         8 . The highly attenuated fiber of  claim 1  wherein the starch is not substituted and has a reduced molecular weight of from about 30,000 g/mol to about 500,000 g/mol.  
     
     
         9 . The highly attenuated fiber of  claim 1  wherein the fiber is thermally bondable.  
     
     
         10 . A nonwoven web comprising the highly attenuated fiber of  claim 9 .  
     
     
         11 . A nonwoven web wherein the highly attenuated fibers of  claim 9  are blended with other synthetic or natural fibers and bonded together.  
     
     
         12 . A disposable article comprising the nonwoven web of  claim 10 .  
     
     
         13 . A highly attenuated fiber produced by melt spinning a composition comprising: 
 a. From about 5% to about 85% of destructurized starch,    b. from about 15% to about 90% of a thermoplastic polymer having a molecular weight of from about 5,000 g/mol to about 500,000 g/mol, and    c. from about 2% to about 70% of a plasticizer,    wherein thermoplastic polymer microfibrils are formed within the starch matrix in the highly attenuated fiber.    
     
     
         14 . The highly attenuated fiber of  claim 13  wherein the thermoplastic polymer microfibrils have a diameter of from about 0.01 micrometers to about 10 micrometers.  
     
     
         15 . The highly attenuated fiber of  claim 13  wherein the diameter of the highly attenuated fiber is less than about 200 micrometers.  
     
     
         16 . The highly attenuated fiber of  claim 13  wherein the thermoplastic polymer is selected from the groups consisting of polypropylene, polyethylene, polyamides, polyvinyl alcohol, polyolefin copolymers, polyolefin carboxylic acid copolymers, ethylene acrylic acid, polyesters, and combinations thereof.  
     
     
         17 . The highly attenuated fiber of  claim 13  wherein the starch is not substituted and has a reduced molecular weight of from about 30,000 g/mol to about 500,000 g/mol.  
     
     
         18 . The highly attenuated fiber of  claim 13  wherein the fiber is thermally bondable.  
     
     
         19 . A nonwoven web comprising the highly attenuated fiber of  claim 18 .  
     
     
         20 . A nonwoven web wherein the highly attenuated fibers of  claim 18  are blended with other synthetic or natural fibers and bonded together.  
     
     
         21 . A disposable article comprising the nonwoven web of  claim 19 .  
     
     
         22 . A nonwoven web comprising highly attenuated fibers comprising destructurized starch, a thermoplastic polymer having a molecular weight of from about 5,000 g/mol to about 500,000 g/mol, and a plasticizer.  
     
     
         23 . A nonwoven web wherein the highly attenuated fibers of  claim 22  are blended with other synthetic or natural fibers and bonded together.  
     
     
         24 . A disposable article comprising the nonwoven web of claim  22 .