Wet-laid microfibers including polyolefin and thermoplastic starch

Abstract

Spun microfibers include a blend of 70 wt. % to 90 wt. % meltblown-grade polyolefin and 10 wt. % to 30 wt. % thermoplastic starch, wherein the microfibers are suitable for use in a wet-laid process. A method for producing an absorbent product includes producing a blend of 70 wt. %-90 wt. % meltblown-grade polyolefin with 10 wt. % to 30 wt. % thermoplastic modified starch (TPMS), wherein the blend prior to spinning has a melt flow index greater than 150; spinning the blend into microfibers in a fiber spinning process; cutting the microfibers into staple fibers; and incorporating the staple fibers into a wet-laid process for making a nonwoven web.

We claim: 
     
         1 . Spun microfibers comprising a blend of 70 wt. % to 90 wt. % meltblown-grade polyolefin and 10 wt. % to 30 wt. % thermoplastic starch, wherein the microfibers are suitable for use in a wet-laid process. 
     
     
         2 . The spun microfibers of  claim 1 , wherein the blend prior to spinning has a melt flow index greater than 150. 
     
     
         3 . The spun microfibers of  claim 1 , wherein the microfibers are staple fibers. 
     
     
         4 . The spun microfibers of  claim 1 , further comprising a surfactant treatment. 
     
     
         5 . The spun microfibers of  claim 1 , the blend further comprising a compatibilizer. 
     
     
         6 . The spun microfibers of  claim 1 , wherein the meltblown-grade polyolefin is polypropylene. 
     
     
         7 . The spun microfibers of  claim 1 , wherein the meltblown-grade polyolefin is polyethylene. 
     
     
         8 . The spun microfibers of  claim 1 , wherein the starch is a native starch derived from cereal grains such as corn, waxy corn, wheat, sorghum, rice, and waxy rice; tubers such as potatoes; roots such as tapioca, sweet potato, and arrowroot; or the pith of the sago palm. 
     
     
         9 . The spun microfibers of  claim 8 , wherein native starch has been modified to become thermoplastic modified starch (TPMS). 
     
     
         10 . A method for producing spun microfibers comprising:
 producing a blend of 70 wt. %-90 wt. % meltblown-grade polyolefin with 10 wt. % to 30 wt. % thermoplastic modified starch (TPMS) derived from native starch; and   spinning the blend into microfibers in a fiber spinning process, wherein the microfibers are suitable for use in a wet-laid process.   
     
     
         11 . The method of  claim 10 , wherein the blend prior to spinning has a melt flow index greater than 150. 
     
     
         12 . The method of  claim 10 , further comprising cutting the microfibers into staple fibers. 
     
     
         13 . The method of  claim 10 , further comprising applying a surfactant treatment to the microfibers. 
     
     
         14 . The method of  claim 10 , wherein the blend further comprises a compatibilizer. 
     
     
         15 . The method of  claim 10 , wherein the meltblown-grade polyolefin is polypropylene. 
     
     
         16 . The method of  claim 10 , wherein the meltblown-grade polyolefin is polyethylene. 
     
     
         17 . The method of  claim 10 , wherein the native starch is derived from cereal grains such as corn, waxy corn, wheat, sorghum, rice, and waxy rice; tubers such as potatoes; roots such as tapioca, sweet potato, and arrowroot; or the pith of the sago palm. 
     
     
         18 . A method for producing an absorbent product, the method comprising:
 producing a blend of 70 wt. %-90 wt. % meltblown-grade polyolefin with 10 wt. % to 30 wt. % thermoplastic modified starch (TPMS), wherein the blend prior to spinning has a melt flow index greater than 150;   spinning the blend into microfibers in a fiber spinning process;   cutting the microfibers into staple fibers; and   incorporating the staple fibers into a wet-laid process for making a nonwoven web.   
     
     
         19 . The method of  claim 18 , further comprising converting the nonwoven web into an absorbent product. 
     
     
         20 . The method of  claim 18 , wherein the absorbent product is a tissue product.