Spunbond, meltblown, and yarn materials and fibers including starch-based polymeric materials

Abstract

Described are very high molecular weight (e.g., over 2 million, such as 3-20 million g/mol) starch-based materials, and formulations including such, which can be spun in spunbond, melt blown, yarn, or similar processes. Even with such very high molecular weights, the formulations can be processed at commercial line speeds, with spinneret shear viscosities of 1000 sec −1 , without onset of melt flow instability. The starch-based material can be blended with one or more thermoplastic materials having higher melt flow index value(s), which serve as a diluent and plasticizer, allowing the very viscous starch-based component to be spun under such conditions. The particular melt flow index characteristics of the thermoplastic diluent material can be selected based on what type of process is being used (e.g., spunbond, melt blown, yarn, etc.). The starch-based material may exhibit high shear sensitivity, strain hardening behavior, and/or very high critical shear stress (e.g., at least 125 kPa).

1 . A polymeric blend for use in forming thin fibers through a melt blown process, the blend comprising:
 a starch-based polymeric material having a water content, including any bound water, of no more than 2%; and   a thermoplastic polymeric material having an MFI as measured at 230° C. under a load of 2.16 kg, of at least 500 g/10 min configured to plasticize the starch-based polymeric material;   wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.   
     
     
         2 . (canceled) 
     
     
         3 . The blend of  claim 1 , wherein the starch-based polymeric material is included in an amount of from 1% to 35% by weight of the blend. 
     
     
         4 . The blend of  claim 1 , wherein the blend exhibits a shear viscosity at 190° C. at 1000 sec −1  of no more than 85 Pa·s. 
     
     
         5 . A melt blown thin fiber suitable for use in manufacture of a nonwoven web, the thin fiber comprising:
 a starch-based polymeric material present in an amount of up to 35% by weight; and   a thermoplastic polymeric material having an MFI as measured at 230° C. under a load of 2.16 kg, of at least 500 g/10 min configured to plasticize the starch-based polymeric material;   wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material;   wherein the melt blown thin fiber has a diameter of no more than about 10 μm.   
     
     
         6 . (canceled) 
     
     
         7 . The thin fiber of  claim 5 , wherein the thin fiber has a diameter of from about 2 μm to about 4 μm. 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . A polymeric blend for use in forming thin fibers through a spunbond process or for use in forming yarn fibers, the blend comprising:
 a starch-based polymeric material having a water content, including any bound water, of no more than 2%; and   a thermoplastic polymeric material having a melt flow index configured to plasticize the starch-based polymeric material;   wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.   
     
     
         12 . (canceled) 
     
     
         13 . The blend of  claim 11 , wherein the starch-based polymeric material exhibits a zero shear viscosity of at least 10 6  or at least 10 7  Pa·s at a process temperature of from 170° C. to 210° C., wherein the shear viscosity is reduced to no more than 125 Pa·s at the process temperature, at a shear rate of 1000 sec −1 . 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . The blend of  claim 11 , wherein the starch-based polymeric material is included in an amount of up to 60%, or from 1% to 35% by weight of the blend. 
     
     
         17 . The blend of  claim 11 , further comprising a thermoplastic elastomer. 
     
     
         18 . The blend of  claim 17 , wherein the thermoplastic elastomer comprises at least one of a random or block poly(propylene/ethylene) copolymer comprised primarily of isotactic propylene repeating units with random ethylene distribution therein, SEBS, SBS, SIS, or another styrenic block copolymer. 
     
     
         19 . The blend of  claim 11 , wherein the thermoplastic polymeric material includes a thermoplastic polymer that is biodegradable on its own under industrial compost conditions. 
     
     
         20 . The blend of  claim 19 , wherein the thermoplastic polymer that is biodegradable under industrial compost conditions comprises PLA, PBAT or another polyester. 
     
     
         21 . The blend of  claim 11 , wherein the blend exhibits a shear viscosity at 190° C. and 1000 sec −1  of no more than 125 Pa·s, from 40 Pa·s to 125 Pa·s, or from 40 Pa·s to 95 Pa·s. 
     
     
         22 . The blend of  claim 11 , wherein the blend exhibits a critical shear stress of at least 125 kPa, while also being strain hardening. 
     
     
         23 . A spunbond nonwoven formed from thin fibers or a yarn fiber, wherein the thin fibers or the yarn fiber comprise:
 a starch-based polymeric material present in an amount of up to 60% by weight; and   a thermoplastic polymeric material having a melt flow index configured to plasticize the starch-based polymeric material;   wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.   
     
     
         24 . The spunbond nonwoven or yarn fiber of  claim 23 , wherein the spunbond nonwoven or yarn fiber is the spunbond nonwoven. 
     
     
         25 . The spunbond nonwoven of  claim 24 , wherein the thin fiber has a diameter of up to 50 μm, or up to 30 μm. 
     
     
         26 . The spunbond nonwoven of  claim 24 , wherein the thin fiber is not smooth, but has a bumpy texture. 
     
     
         27 . The spunbond nonwoven of  claim 26 , wherein bumps making up the bumpy texture consist essentially of the starch-based polymeric material. 
     
     
         28 . The spunbond nonwoven of  claim 24 , wherein bumps making up the bumpy texture exhibit a dis-uniformity relative to a smooth fiber surface, the dis-uniformity being from 1-5 μm relative to a diameter of the fiber. 
     
     
         29 . The spunbond nonwoven of  claim 24 , wherein the thin fiber is a bicomponent fiber. 
     
     
         30 . (canceled) 
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . (canceled) 
     
     
         34 . (canceled) 
     
     
         35 . (canceled) 
     
     
         36 . (canceled) 
     
     
         37 . (canceled) 
     
     
         38 . (canceled) 
     
     
         39 . The blend of  claim 11 , for use in forming yarn fibers,
 wherein the thermoplastic polymeric material has a melt flow index as measured at 230° C. under a load of 2.16 kg, of from 10 g/10 min to 100 g/10 min, configured to plasticize the starch-based polymeric material;   wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.   
     
     
         40 . (canceled) 
     
     
         41 . (canceled) 
     
     
         42 . (canceled) 
     
     
         43 . The spunbond nonwoven or yarn fiber of  claim 23 , wherein the spunbond nonwoven or yarn fiber is the yarn fiber. 
     
     
         44 . (canceled) 
     
     
         45 . (canceled) 
     
     
         46 . (canceled) 
     
     
         47 . (canceled) 
     
     
         48 . (canceled) 
     
     
         49 . (canceled)