Nonwoven materials and fibers comprising starch-based polymeric materials

Abstract

Very high molecular weight (e.g., over 2 million g / mol, such as 3 million g / mol to 20 million g / mol) starch-based materials are described, as well as formulations comprising the starch-based materials that are capable of being spun in a spunbond, meltblown, yarn, or similar process. Even with such very high molecular weights, the formulations are capable of being processed at commercial line speeds where the spinneret shear viscosity is 1000 s ‑1 The starch-based materials are capable of being blended with one or more thermoplastic materials having higher melt flow index values that act as diluents and plasticizers, allowing the very viscous starch-based components to be spun under such conditions. The specific melt flow index properties of the thermoplastic diluent materials can be selected based on what type of process is being used (e.g., spunbond, meltblown, yarn, etc.). The starch-based materials can exhibit high shear sensitivity, strain hardening behavior, and / or very high critical shear stress (e.g., at least 125 kPa).

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of U.S. Application No. 63 / 033,676 (21132.31), filed June 2, 2020; U.S. Application No. 17 / 327,536 (21132.31.1), filed May 21, 2021; U.S. Application No. 17 / 327,577 (21132.31.2), filed May 21, 2021; and U.S. Application No. 17 / 327,590 (21132.31.3), filed May 21, 2021, each of which is incorporated herein by reference in its entirety.

[0003] This application also incorporates by reference each of the following applications: U.S. Application No. 16 / 925,747 (21132.30.1), filed July 10, 2020; U.S. Application No. 16 / 925,952 (21132.28.1.1), filed July 10, 2020; U.S. Application No. 16 / 925,705 (21132.27.1.1), filed July 10, 2020; U.S. Patent Application No. 16 / 425,397 (21132.20.1), filed May 29, 2019; U.S. Patent Application No. 16 / 391,909 (21132.14.1), filed April 23, 2019; U.S. Application No. 15 / 691,588 (21132.7), filed August 30, 2017; U.S. Application No. 14 / 853,725 (21132.8), filed September 14, 2015; U.S. Provisional Patent Application No. 62 / 187,231, filed June 30, 2015; U.S. Application No. 14 / 853,780 (21132.6), filed September 14, 2015; U.S. Application No. 15 / 481,806 (21132.1) and U.S. Application No. 15 / 481,823 (21132.2), filed April 7, 2017; U.S. Provisional Patent Application No. 62 / 440,399 (21132.10), filed December 29, 2016; U.S. Provisional Patent Application No. 62 / 442,432 (21132.11), filed January 4, 2017; U.S. Application No. 16 / 456,303 (21132.9.1), filed June 28, 2019 (now U.S. Patent No. 10,752,759); and U.S. Patent Application No. 15 / 836,555 (21132.4.1), filed December 8, 2017. BACKGROUND

[0004] Traditional petrochemical-based plastics are formulated to be strong, lightweight, and durable. As such, they are used in large quantities in countless consumer products. However, these plastics are often not derived from sustainable materials, are often not biodegradable to any significant degree, and as a result, hundreds of millions of tons of plastics persist in landfills or other natural environments (oceans, other waterways, soil, etc.). In an attempt to reduce the amount of plastic waste, some articles that are typically produced using petrochemical-based plastics are produced using more rapidly biodegradable materials, and / or from a portion of components derived from renewable resources.

[0005] Many such plastic materials are manufactured in the form of nonwoven, fiber-based substrates, or other articles comprising fine fibers. While some progress has been made in incorporating renewable-derived components into some monolithic plastic articles and even plastic film materials, little success has been achieved in incorporating such renewable components into nonwoven materials and similar articles formed from fine fibers. This lack of progress is particularly applicable to incorporating starch-based polymeric materials into such articles. This is largely attributable to the typically high molecular weight and complex branched nature of typical starch materials, which typically comprise a significant amount of branched amylopectin. The high molecular weight and accompanying high viscosity characteristics make incorporation of such materials into nonwovens and other fine fibers difficult, where rheological properties must be carefully controlled in order to effectively form fibers for use in spunbond, meltblown, yarn, carded, airlaid, and similar processes using the desired thermoplastic formulation.

[0006] As noted above, most petrochemical-based plastic materials, including those used to produce nonwovens, are not readily biodegradable. Examples of such plastic materials include, but are not limited to, polyethylene, polypropylene, polyethylene terephthalate, polyesters, polystyrene, ABS, polyvinyl chloride, polycarbonate, nylon, and the like. Such non-biodegradable characteristics are often the case with so-called “green” versions of such materials (e.g., green PE manufactured by Braskem), which can be derived from renewable resources, rather than petrochemical feedstocks. The “green” versions of such plastics differ little, if at all, in physical properties from their fossil fuel-derived cousins, and can be distinguished, for example, by subtle differences such as their C 14 content relative to C 12 content, etc. Even in cases where some components of the plastic material can be obtained from renewable resources, the inclusion of starch-based polymeric materials tends to result in materials that are not capable of being manufactured into nonwovens, for example, by typical spunbond, meltblown, yarn production, and similar processes, due to the poor rheological properties of the resulting materials as a result of the inclusion of the starch-based components in such formulations.

[0007] While the literature describes some attempts to incorporate starch or starch derivatives into blends of petrochemical or other plastic materials used to form nonwovens, such attempts have had little commercial success, if any, due to problems such as those described above, increased cost, need to slow production lines to accommodate such formulations, poor physical properties of the blends, and the like. For example, while U.S. Patents 6,818,295, 6,946,506, 7,666,261, U.S. Publications 2002 / 0168518, 2002 / 0188041, 2003 / 0077444, 2010 / 0159777, 2019 / 0330770, and EP 326517 Al can describe various attempts in making nonwoven articles that will contain starch-based polymeric materials, the Applicant is not aware of any products currently on the market that provide any of the above attempts, for example, due to the problems described above.

[0008] For example, U.S. Patent 7,666,261 to P&G describes a composition comprising starch, a high MW polymer that is substantially compatible with the starch and has a molecular weight high enough to form effective entanglements or associations with adjacent starch molecules, and at least one additive that improves melt flow and melt processability. The composition is generally predominantly starch with a small amount (e.g., <10%) of added high molecular weight polymer. The starch needs to be modified, for example, by reducing the molecular weight to a value of 2 million or less. The starch composition retains about 5-8% bound water even after forming fibers or other articles. The reference mentions the formation of small fibers (e.g., 5 pm or less).

[0009] U.S. Patent 6,946,506, also to P&G, describes a starch composition comprising starch and a biodegradable polymer. Non-biodegradable polymers can also be present (e.g., up to 40%). The composition generally comprises a high content of starch (e.g., typically 40-60%), and a similar content of biodegradable polymer (e.g., a crystallizable PLA is specifically described). The starch composition retains about 5-16% bound water. Small fibers (e.g., 10-50 pm) can be formed, it is reported. The starch needs to be modified to have a molecular weight of no more than 2 million to be suitable for use.

[0010] U.S. Patent 6,818,295, also assigned to P&G, describes a starch composition comprising starch, a thermoplastic polymer (e.g., PE, PP, PCL), and a plasticizer. As in the examples, an acid-substituted vinyl polymer such as ethylene acrylic acid (Dow Primacor) can be added. It is mentioned that highly refined fibers can be produced, including microfibers formed with a starch matrix. Similar to the '506 patent described above, the composition generally comprises a high content of starch (e.g., 40%-60%) with a similar content of thermoplastic polymer. The starch composition retains about 5%-16% bound water. It is reported that small fibers (e.g., 5 μm-30 μm) can be formed. It is mentioned that the starch needs to be modified to have a molecular weight of no more than 8 million, typically no more than 2 million. Although a molecular weight value of up to 8 million can be mentioned, there is no evidence of successful use of such a molecular weight value. For example, each of the examples in the patent uses a StarDri 100, StaDex 10, or StaDex 65 starch product from Staley, and although the actual molecular weight of such products is not mentioned in the patent, it is believed that they have a weight average molecular weight of no more than about 1 million, as the applicants have measured a weight average molecular weight of only about 21,000 Daltons for StarDri 100.

[0011] U.S. Publication 2003 / 0077444, assigned to P&G, recognizes that fiber formation is more difficult than other article formation methods (injection molding, blown film, etc.) because the time for structure formation is very short, requiring very specific rheological properties and other properties to form suitable fibers. Starch is particularly problematic because even if starch can be formed into fibers, it has low tensile strength, is tacky, and does not bond well when trying to form a nonwoven web. Blending the starch with a thermoplastic polymer helps, although there are very specific requirements (e.g., melt temperature, spinning characteristics) for doing so. The fibers in this reference are specifically bicomponent fibers (e.g., sheath / core, fan cake, etc.). Although natural starch can have a MW of up to 60 million and a broad molecular weight distribution, the starch needs to be modified to have a MW of 2 million or less to work properly. The content of starch is typically 40%-60%, although it can be higher or lower. A molecular weight that is too high for any particular component will make the composition difficult to melt spin. Preferred polymers for blending include PP, PE, polyamide, PVA, ethylene acrylic acid, polyester, etc. The thermoplastic polymer is typically present at 40%-60%, although it can be higher or lower. Spunbond nonwoven web structures can be formed from such fibers. The fiber diameter is typically reported to be 5 μm-30 μm. At least 15% of the polymer is needed to achieve thermal bondability.

[0012] U.S. Publication 2002 / 0188041 to P&G includes similar disclosure as U.S. Patent 2003 / 0077444 and more specifically relates to fibers comprising starch, plasticizer, and a biodegradable thermoplastic polymer.

[0013] U.S. Publication 2010 / 0159777 to Kimberly-Clark describes a thermoplastic starch that has been enzymatically debranched (reducing the amylopectin fraction) to increase the amylose content to 55-60%. The composition also includes a plasticizer. The apparent melt viscosity at 1000 s -1 Figure 5 as shown, the molecular weight of the debranched starch is allegedly up to 5 million, but more typically 80-200 million, or significantly less than 200 million, after enzymatic debranching.

[0014] U.S. Publication 2019 / 0330770, also to Kimberly-Clark, describes spun fibers formed from a blend of 70-90% polyolefin (e.g., PP or PE) and 10-30% starch for use in a wet-laid nonwoven manufacturing process. The starch is said to have a weight average molecular weight of 5-25 million, although no examples demonstrate success at such high molecular weights, and as with other references, it appears that the molecular weight must be reduced to be suitable for use, as the examples reporting actual use report a molecular weight of 2.9 million. This patent points out the problem in earlier (2000-2010) references, such as those above, that the blends do not actually work for running at commercial line speeds because the fibers break.

[0015] EP 326517A1 simply describes a method for destroying starch.

[0016] It would be advantageous in the art to provide fibers, nonwoven articles, and methods for making each, where such fibers and nonwoven articles can include very high molecular weight starch-based polymeric materials (e.g., having a molecular weight significantly higher than any of the materials successfully demonstrated in the references above). It would be further advantageous if the inclusion of such starch-based polymeric materials would enhance or at least not significantly reduce the mechanical properties of such fibers, nonwovens, etc. compared to the base resin material used alone. It would be yet another advantage if such compositions could be processed into fibers and nonwoven webs on conventional equipment at commercial line speeds, whether using a spunbond, meltblown, yarn production process, or other similar process involving production of fine fibers from a polymer blend.

[0017] SUMMARY ​Applicant's co-pending applications incorporated herein by reference disclose starch-based polymeric materials (e.g., thermoplastic starch materials) that can be blended with a variety of plastic resin materials while substantially maintaining the desired strength and other physical properties of the material blended with the renewable starch-based material. It is believed that such starch-based materials, available under the trade name NuPlastiQ, achieve strong intermolecular bonding between the starch-based material and the plastic resin with which it is blended. Such strong bonding is in contrast to the bonding achieved by many in the art attempting to blend such plastic resins with starch or starch-based materials, where the starch or starch-based material merely acts as a filler, often reducing strength and negatively impacting other physical properties.

[0018] Applicants have now discovered that at least some grades of their starch-based polymeric materials having very high molecular weight can be formed into fine fibers, e.g., that can be used to form nonwoven web substrates (e.g., for, but not limited to, diapers, sanitary napkins, disposable drapes, gowns, surgical and other face masks, pantiliners, wet wipes, etc.). Such fine fibers can be produced by a spunbond, meltblown, yarn production process, or other similar extrusion spinning process that produces a fine fiber structure from a polymer melt or blend. As used herein, "spinning" refers to such processes (spunbond, meltblown, yarn spinning, or similar extrusion processes used to spin fine fibers). While there are some technologies that incorporate starch into fibers to some extent to make nonwoven webs, careful control of the molecular weight of the starch component included in such compositions is critical in order to make the composition processable under the desired spinning conditions. For example, the above-referenced references demonstrate the formation of fibers whose starch component is strictly controlled (e.g., molecular weight no more than 2 million) and where the starch component generally exhibits other characteristics (e.g., water content, including 5-16% bound water) that are also different from those of the present embodiments. While it is reported that native starches sometimes include molecular weight values far in excess of 2 million, none of the prior art known to Applicants has successfully demonstrated the ability to actually spin a composition and make fabrics (e.g., nonwovens) or other fibrous products from it that include such very high molecular weight starch materials. This is especially true given that the viscosity increases exponentially with increasing molecular weight, such that it would be considered impossible by those skilled in the art (including at least some of the present inventors) to spin a starch component having a very high molecular weight (e.g., 5-10 million or higher). For example, it would be expected to be impossible to achieve the rheological properties required to be able to spin such a composition where the starch-based polymer is included in the formulation to any significant extent and has such a high molecular weight.

[0019] According to one embodiment, the present application is directed to a method for spinning a composition comprising a high molecular weight starch-based polymeric material (e.g., having a weight average molecular weight of greater than 2 million, 3 million, 4 million, or 5 million), by providing such starch-based polymeric material, and spinning the composition at a suitable temperature (e.g., in a range of 170 °C to 230 °C, up to 205 °C, or up to 195 °C), for example, at a shear rate of an exemplary commercial spinning line (e.g., about 200 s -1 of the process shear rate, at a spinneret shear rate of about 1000 s -1 or more). Under such conditions, and using the particular formulations described herein, the composition can exhibit a spinneret shear viscosity of no more than about 125 Pa-s, no more than 120 Pa-s, no more than 115 Pa-s, no more than 110 Pa-s, no more than 105 Pa-s, no more than 100 Pa-s, no more than 95 Pa-s, no more than 90 Pa-s, no more than 85 Pa-s, no more than 80 Pa-s, no more than 75 Pa-s, no more than 70 Pa-s, no more than 65 Pa-s, no more than 60 Pa-s, no more than 55 Pa-s, no more than 50 Pa-s, no more than 45 Pa-s, no more than 40 Pa-s, no more than 35 Pa-s, no more than 30 Pa-s, no more than 25 Pa-s, or no more than 20 Pa-s (e.g., at 1000 s -1 and 190 °C). Similarly, the composition can exhibit a process shear viscosity of no more than about 600 Pa-s, no more than 500 Pa-s, no more than 400 Pa-s, no more than 300 Pa-s, no more than 275 Pa-s, no more than 250 Pa-s, no more than 240 Pa-s, no more than 230 Pa-s, no more than 220 Pa-s, no more than 210 Pa-s, no more than 200 Pa-s, no more than 190 Pa-s, no more than 180 Pa-s, no more than 170 Pa-s, no more than 160 Pa-s, no more than 150 Pa-s, no more than 140 Pa-s, or no more than 130 Pa-s (e.g., at 200 s -1and 190°C). This rheological behavior is possible even when including a significant portion of starch-based polymeric material having very high molecular weight, with the process effectively producing fibers comprising high molecular weight starch-based polymeric material. Because the actual shear threshold can differ depending on the process employed (e.g., spunbond versus meltblown versus yarn), more generally, the process and formulation can simply be configured to provide a shear viscosity low enough for the formulation to pass through the system at commercial line speeds and shear rates, with the formulation exhibiting a rheology that allows it to avoid melt flow instabilities within the system, especially at the spinneret, whether in spunbond, meltblown, yarn, or other processes. The above values include both the spinneret shear viscosity and the process shear viscosity for each of these processes. In a more specific example, the shear viscosity for meltblown can be lower than the shear viscosity for spunbond, which can be lower than the shear viscosity for yarn. For example, the meltblown process shear viscosity can be less than 200 Pa-s, such as 30 Pa-s to 180 Pa-s, or 50 Pa-s to 150 Pa-s. The meltblown spinneret shear viscosity can be less than 95 Pa-s, less than 80 Pa-s, or less than 60 Pa-s, such as 20 Pa-s to 70 Pa-s, or 30 Pa-s to 60 Pa-s. The spunbond process shear viscosity can be less than 300 Pa-s, or less than 225 Pa-s, such as 130 Pa-s to 215 Pa-s, or 150 Pa-s to 200 Pa-s. The spunbond spinneret shear viscosity can be less than 95 Pa-s, such as 50 Pa-s to 85 Pa-s, or 60 Pa-s to 80 Pa-s. The yarn process shear viscosity can be less than 600 Pa-s, less than 500 Pa-s, less than 400 Pa-s, or less than 300 Pa-s, such as 100 Pa-s to 275 Pa-s, or 150 Pa-s to 250 Pa-s. The yarn spinneret shear viscosity can be less than 120 Pa-s, such as 50 Pa-s to 95 Pa-s, or 75 Pa-s to 95 Pa-s.

[0020] As described herein, and as can be appreciated by one of skill in the art, formulations comprising starch-based polymeric materials can be formulated differently (e.g., with diluent plasticizer polymers, such as added to a masterbatch formulation comprising the starch-based polymeric material) to be passed through a given particular process. For example, a formulation specifically tailored for a meltblown production process can have a lower shear viscosity characteristic than a spunbond process, and a spunbond formulation can have a lower shear viscosity characteristic than a yarn production process. Each formulation can be tailored to ensure that the shear viscosity is configured to pass through a fiber spinning process (e.g., meltblown, spunbond, yarn, or other process), while avoiding melt flow instabilities. By way of broad example, a meltblown formulation can be formulated with a starch-based polymeric material comprising a particular diluent plasticizing polymer to provide a process shear viscosity of less than 200 Pa-s (e.g., at 200 s -1 below). A spunbond formulation can be formulated with a starch-based polymeric material comprising a particular diluent plasticizing polymer to provide a process shear viscosity of less than 300 Pa-s (e.g., at 200 s -1 below). A yarn production formulation can be formulated with a starch-based polymeric material comprising a particular diluent plasticizing polymer to provide a process shear viscosity of less than 600 Pa-s (e.g., at 200 s -1 below). As described above, in any case, the formulation can be tuned (by selection of the diluent plasticizing polymer) to provide a shear viscosity low enough to pass through a given process, while avoiding melt flow instabilities. The formulation can also advantageously provide an elongation or extensional viscosity value (used interchangeably herein) within a desired window to allow fiber formation. For example, if the extensional viscosity is too low, the fiber will break, and if the extensional viscosity is too high, the fiber will not stretch as desired.

[0021] Under any such fiber production process conditions, it is important to maintain the formulation from experiencing melt flow instabilities, for example desirably below 100 kPa for a polypropylene-based formulation. As will be apparent to one of skill in the art, melt flow instabilities occur when a critical shear stress is exceeded (e.g., about 100 kPa for a typical polypropylene). Such critical shear stress values are independent of temperature, but rather depend on the material properties of the formulation (e.g., molecular structure, etc.). Above this critical shear stress, rough surface irregularities associated with entrance breakup and / or plateau breakup can occur, resulting in undesirable or unusable manufactured products due to irregularities in the surface of the extruded product. Other properties that can be associated with melt flow instabilities (also undesirable) include, but are not limited to, draw resonance (resulting in extrusion thickness pulsations) and secondary flow (resulting in interphase issues in multi-layer extruded products).

[0022] While lower molecular weight starch-based materials (e.g., having a molecular weight of 1 million or perhaps even less) can prove suitable for use, by way of example, in one embodiment, the starch-based polymeric material can have a weight average molecular weight of 3 million to 20 million or 5 million to 16 million, although clearly lower molecular weight values can prove suitable for use. By way of further example, exemplary starches forming the starch-based polymeric material (e.g., formed from starch and plasticizer) can have a weight average molecular weight of at least 2 million, 3 million, 4 million or 5 million, such as 3 million to 10 million or 5 million to 7 million. The starch-based polymeric material can be formed from starch having a particular amylose content, for example, an amylose content of at least 10%, at least 20% or at least 30%, such as 20% to 70% or 30% to 50% amylose. Any suitable extrusion temperature can be used, such as at least 110°C or at least 130°C (e.g., 130°C to 250°C). Extrusion of the starch and plasticizer can occur under pressurized conditions.

[0023] In one embodiment, the starch-based polymeric material is blended with a thermoplastic polymeric diluent material capable of further plasticizing the starch-based polymeric material, for example, polypropylene having a high melt flow index (e.g., at least 35, at least 50, at least 100, such as 35 to 2000, 35 to 1550, 35 to 1000 or 35 to 500). The melt flow index (MFI) of the diluent material selected can depend on the process by which the formulation is provided. For example, meltblown processes can employ a diluent having a relatively high MFI, spunbond can employ a diluent having an intermediate MFI, and yarn processes can employ a diluent having a relatively low MFI. Applicants have discovered that, although currently prepared starch-based polymeric materials can have very high molecular weights (and thus very high viscosity characteristics), this makes transport, shearing and spinning very difficult, that particular starch-based polymeric materials as described herein: (i) appear to be strain hardening (whereas other starches appear to be strain thinning); (ii) exhibit high shear sensitivity, i.e., the material is shear thinning, thus shear rate can be used to significantly improve flow characteristics; (iii) exhibit excellent responsiveness to diluent / plasticizer (where addition of small amounts of such polypropylene or similar thermoplastic polymers having a given melt flow index also significantly affect flow characteristics); and (iv) exhibit relatively high critical shear stress characteristics (e.g., higher than polypropylene). In addition, the prepared starch-based polymeric material exhibits (v) excellent responsiveness to extrusion temperature (where the material exhibits significantly reduced viscosity as extrusion temperature is increased).

[0024] Such properties do not appear to be inherent in other starch-based polymeric materials, and indeed, at least some of such properties appear to be contrary to those of conventional starch-based polymeric materials (e.g., the starch-based materials of the present invention appear to be strain hardening, whereas other TPS are strain thinning). Strain hardening and strain thinning are not to be confused with shear thickening and shear thinning. For example, shear thickening or shear thinning relates to how a material behaves when shear is applied (e.g., whether the material thickens or thins when shear is applied). In contrast, strain hardening and strain thinning relate to how a material behaves as a function of time under strain. A material is strain hardening if it exhibits increasing extensional or elongational viscosity over time during the process of stretching. From the literature, it can be inferred that typical starch materials, while certainly used for thickening, do not exhibit strain hardening behavior, in which their extensional or elongational viscosity increases when they are stretched at the spinneret. Rather, existing starch materials appear to be too thin at this critical manufacturing stage, resulting in materials that tend to stretch to a point and then break. Additionally, the particular starch that forms the starch-based polymeric NuPlastiQ material can affect such properties (e.g., the selection of different grades of corn starch, tapioca starch, potato starch, etc. used to make the high molecular weight starch base material can affect the rheology of the resulting material, as described below). In any case, suitable starch-based polymeric materials for forming melt-blown, spun-bond, or yarn fibers as described herein are available from the Applicant hereunder the trade name NuPlastiQ.

[0025] In comparison to the starch-based materials described in the literature as suitable for spinning, the NuPlastiQ starch-based materials exhibit lower water content (e.g., <2% total water content, including bound water, whereas the water content of the materials described in the literature is 5% or more).

[0026] Another embodiment relates to polymer blends suitable for forming fine fibers, such as can be used to form nonwoven webs for meltblown processes or for producing yarns via a spunbond process. Such compositions include a starch-based polymeric material (e.g., having a weight average molecular weight as described herein) and a thermoplastic polymeric diluent material having a melt flow index configured to further plasticize the starch-based polymeric material to provide overall desired rheological properties. The melt flow index (MFI) of the diluent material can depend on whether the formulation is to be configured for a spunbond process, a meltblown process, or a yarn process (or other process), with the MFI of the diluent being particularly selected to ensure: (1) that the resulting formulation has a sufficiently low shear viscosity to be processed through the system; (2) that the resulting formulation avoids melt flow instabilities upon extrusion through the spinneret of the system; and (3) that the formulation provides an appropriate elongation viscosity to allow the fibers to be stretched without breaking. The two components (the starch-based polymeric material such as NuPlastiQ and the thermoplastic polymeric diluent) are generally intimately dispersed with one another. In one embodiment, the starch-based polymeric material can be present in an amount of up to 75 wt%, up to 60 wt%, up to 50 wt%, or up to 40% of the blend. The thermoplastic polymer can be present in an amount of up to 95 wt% or up to 90 wt% (e.g., more typically up to 75%) of the blend. Of course, in other embodiments, the percentage of starch content can be further increased, such as by adjusting other manufacturing parameters as mentioned herein (e.g., increasing process temperature within the degradation range of high molecular weight NuPlastiQ or other starch-based polymeric material, increasing shear rate, etc.).

[0027] Another embodiment relates to fine fibers. Such fine fibers can be suitable for use in making nonwoven webs (e.g., whether formed in a spunbond process or in a meltblown process), for example. Fine fibers formed in a yarn process can be used to produce yarn products, or to produce carded fibers, air-laid fibers, or wet-laid fibers, for example. As will be appreciated by those skilled in the art, such examples are merely exemplary, and such fine fibers produced by any of a variety of fiber spinning processes can be used in any of a variety of uses. Such fibers and nonwoven webs include a starch-based polymeric material (e.g., NuPlastiQ) as described herein (e.g., present in an amount of up to 60%) and a thermoplastic polymeric material having a melt flow index configured to plasticize the starch-based polymeric material to have the rheological properties required by whatever spinning process is being employed. The components can be intimately dispersed together throughout the fiber. Of course, various non-uniform fiber geometries (e.g., sheath / core, side-by-side, fan cake, islands in a sea, splittable fibers, or other geometries) can also be realized if desired.

[0028] Another embodiment relates to a method for increasing the critical shear stress threshold of a spun or other extruded and fiber drawn formulation or related process, where the method includes providing a thermoplastic spun or other extruded and fiber drawn formulation having an initial critical shear stress of a given value (e.g., less than 300 kPa, less than 200 kPa, or less than 125 kPa, such as about 100 kPa), and adding a starch-based polymeric material having a critical shear stress greater than that of the thermoplastic extruded formulation to such formulation. By way of example, the starch-based polymeric material itself can have a critical shear stress greater than 200 kPa or greater than 300 kPa. The addition of this material can increase the critical shear stress to a value greater than 100 kPa, such as to 125 kPa or 150 kPa, even when blended as part of a masterbatch. In any case, the result is that the starch-based polymeric material increases the initial critical shear stress of the formulation. In one embodiment, the starch-based polymeric material can be added as part of a masterbatch (e.g., NuPlastiQ ) where the starch-based polymeric material has been blended with a given thermoplastic material. Such a masterbatch blend can have a lower critical shear stress than the starch-based polymeric material alone, but still higher than the formulation to which it is added. By way of example, such a masterbatch “BioBlend” can include 50% of the starch-based polymeric material. By way of further example, the masterbatch BioBlend can have a critical shear stress value of at least 110 kPa, at least 115 kPa, at least 120 kPa, at least 125 kPa, at least 150 kPa, at least 175 kPa, or at least 200 kPa.

[0029] [Embodiment 1] One embodiment relates to a method for spinning a composition including a starch-based polymeric material to produce a spunbond nonwoven, a meltblown fine fiber, or a yarn fiber made therefrom, the method comprising:

[0030] providing a composition including a starch-based polymeric material; and performing at least one of (a), (b), or (c):

[0031] (a) melt spinning the composition to produce a fiber including the starch-based polymeric material, where the composition exhibits a shear viscosity of no more than about 300 Pa s at 190 °C under a process shear rate of 200 s -1 and melt flow instabilities are avoided during the melt spinning process; or

[0032] (b) melt blowing the composition to produce a fiber including the starch-based polymeric material, where the composition exhibits a shear viscosity of no more than about 300 Pa s at 190 °C under a process shear rate of 200 s -1a shear viscosity of no more than about 200 Pa-s at a process shear rate of 200 s

[0033] (c) spinning the composition to produce a yarn fiber having a spun diameter of about 40 pm to about 150 pm, the yarn fiber comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity of no more than about 600 Pa-s at a process shear rate of 200 s -1 and avoids melt flow instabilities during spinning of the yarn fiber; and drawing the spun yarn fiber from its spun diameter to a smaller diameter.

[0034] [Embodiment 2] The method of embodiment 1, wherein the method comprises performing (a), and the composition exhibits a shear viscosity of no more than about 300 Pa-s at a process shear rate of 200 s -1 and a shear viscosity of no more than about 125 Pa-s at a spinneret shear rate of 1000 s -1 at 190 °C.

[0035] [Embodiment 3] The method of embodiment 1, wherein the method comprises performing (a), and wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0036] [Embodiment 4] The method of embodiment 1, wherein the method comprises performing (a), and wherein the composition is a blend of the starch-based polymeric material and at least one thermoplastic polymer.

[0037] [Embodiment 5] The method of embodiment 4, wherein the at least one thermoplastic polymer comprises a polymer having a melt flow index greater than 100 g / 10 min, 200 g / 10 min to 1000 g / 10 min, or 400 g / 10 min to 600 g / 10 min as measured at 230 °C under a load of 2.16 kg.

[0038] [Embodiment 6] The method of embodiment 4, wherein the at least one thermoplastic polymer comprises at least two grades of polypropylene, a first grade having a melt flow index of 400 g / 10 min to 600 g / 10 min as measured at 230 °C under a load of 2.16 kg, a second grade having a melt flow index of less than 100 g / 10 min as measured at 230 °C under a load of 2.16 kg, and an optional third grade having a melt flow index of 75 g / 10 min to 125 g / 10 min as measured at 230 °C under a load of 2.16 kg.

[0039] [Embodiment 7] The method of embodiment 6, wherein the at least one thermoplastic polymer further comprises an additional grade of polypropylene having both isotactic structure and atactic structure, the polypropylene having a melt flow index of less than 1000 g / 10 min as measured at 230 °C under a load of 2.16 kg.

[0040] [Embodiment 8] The method of embodiment 4, wherein the at least one thermoplastic polymer comprises a thermoplastic polymer that is biodegradable on its own under industrial composting conditions.

[0041] [Embodiment 9] The method of embodiment 8, wherein the thermoplastic polymer that is biodegradable on its own under industrial composting conditions is a polyester.

[0042] [Embodiment 10] The method of embodiment 1, wherein the method comprises performing (a), and wherein the starch-based polymeric material has a water content of no more than 2%, including any bound water.

[0043] [Embodiment 11] The method of embodiment 1, wherein the method comprises performing (a), and wherein the method produces fibers having a diameter of about 10 pm to about 50 pm.

[0044] [Embodiment 12] The method of embodiment 1, wherein the method comprises performing (a), and wherein the starch-based polymeric material is included in the composition in an amount of up to 60 wt%, up to 40 wt%, or in an amount of 1 wt% to 35 wt%.

[0045] [Embodiment 13] The method of embodiment 1, wherein the method comprises performing (a), and wherein the starch-based polymeric material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

[0046] [Embodiment 14] A polymer blend for forming fine fibers by a spunbond process, the blend comprising:

[0047] a starch-based polymeric material having a water content of no more than 2%, including any bound water;

[0048] a thermoplastic polymeric material having a melt flow index configured to plasticize the starch-based polymeric material;

[0049] wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.

[0050] [Embodiment 15] The blend of Embodiment 14, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0051] [Embodiment 16] The blend of Embodiment 15, wherein the high molecular weight starch-based polymeric material exhibits a zero shear viscosity of at least 10 6 Pa-s at a process temperature of 170°C to 210°C, wherein the shear viscosity decreases to no more than 125 Pa-s at the process temperature and a shear rate of 1000 s 7 -1

[0052] [Embodiment 17] The blend of Embodiment 14, wherein the blend further comprises a compatibilizer.

[0053] [Embodiment 18] The blend of Embodiment 14, wherein the starch-based polymeric material has a water content of no more than 2%, including any bound water.

[0054] [Embodiment 19] The blend of Embodiment 14, wherein the starch-based polymeric material is included in an amount of up to 60 wt% or 1 wt% to 35 wt% of the blend.

[0055] [Embodiment 20] The blend of Embodiment 14, further comprising a thermoplastic elastomer.

[0056] [Embodiment 21] The blend of Embodiment 20, wherein the thermoplastic elastomer comprises at least one of: a random or block poly(propylene / ethylene) copolymer consisting essentially of isotactic propylene repeat units with random ethylene distribution therein, SEBS, SBS, SIS, or another styrene block copolymer.

[0057] ​​[Embodiment 22] The blend of Embodiment 14, wherein the thermoplastic polymeric material comprises a thermoplastic polymer that is biodegradable on its own under industrial composting conditions.

[0058] [Embodiment 23] The blend of Embodiment 22, wherein the thermoplastic polymer that is biodegradable under industrial composting conditions comprises PLA, PBAT, or another polyester.

[0059] [Embodiment 24] The blend of Embodiment 14, wherein the blend exhibits a shear viscosity of no more than 125 Pa-s, 40 Pa-s to 125 Pa-s, or 40 Pa-s to 95 Pa-s at 190°C and 1000 s -1

[0060] [Embodiment 25] The blend of Embodiment 14, wherein the blend exhibits a critical shear stress of at least 125 kPa while also being strain hardening.

[0061] [Embodiment 26] A spunbond nonwoven formed from fine fibers, wherein the fine fibers comprise:

[0062] a starch-based polymeric material present in an amount up to 60 wt.%; and

[0063] a thermoplastic polymeric material having a melt flow index configured to plasticize the starch-based polymeric material;

[0064] wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.

[0065] [Embodiment 27] The spunbond nonwoven of Embodiment 26, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having an average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0066] [Embodiment 28] The spunbond nonwoven of Embodiment 26, wherein the fine fibers have a diameter up to 50 pm or up to 30 pm.

[0067] [Embodiment 29] The spunbond nonwoven of Embodiment 26, wherein the fine fibers are not smooth but have a raised texture.

[0068] [Embodiment 30] The spunbond nonwoven of Embodiment 29, wherein the protrusions making up the raised texture consist essentially of the starch-based polymeric material.

[0069] ​[Embodiment 31] The spunbond nonwoven according to Embodiment 26, wherein the protrusions making up the protrusion texture exhibit a non-uniformity relative to the smooth fiber surface of 1 pm to 5 pm relative to the diameter of the fiber.

[0070] [Embodiment 32] The spunbond nonwoven according to Embodiment 26, wherein the fine fibers are bicomponent fibers.

[0071] [Embodiment 33] The spunbond nonwoven according to Embodiment 32, wherein the bicomponent fibers have a diameter of no more than 50 pm and have a sheath / core geometry, wherein the core or sheath comprises the starch-based polymeric material.

[0072] [Embodiment 34] The spunbond nonwoven according to Embodiment 33, wherein the ratio of the sheath / core is 50 / 50 to 5 / 95.

[0073] [Embodiment 35] The spunbond nonwoven according to Embodiment 26, wherein the thermoplastic polymeric material is not biodegradable on its own and the high molecular weight starch-based material increases the biodegradability of the thermoplastic polymeric material that is not biodegradable on its own.

[0074] [Embodiment 36] The spunbond nonwoven according to Embodiment 35, wherein at least 20% of the thermoplastic polymeric material that is not biodegradable on its own biodegrades within 3 years according to ASTM D-5338 or ASTM D-5511.

[0075] [Embodiment 37] The spunbond nonwoven according to Embodiment 26, wherein the nonwoven exhibits increased hydrophilicity, wettability, and / or absorbency compared to a nonwoven formed from polypropylene but not containing the starch-based polymeric material.

[0076] [Embodiment 38] A method for increasing the critical shear stress threshold of a spinning formulation, the method comprising:

[0077] providing a thermoplastic spinning formulation having an initial critical shear stress of less than 125 kPa; and

[0078] adding to the thermoplastic spinning formulation a starch-based polymeric material having a critical shear stress of greater than 125 kPa, the starch-based polymeric material increasing the initial critical shear stress of the spinning formulation.

[0079] [Embodiment 39] The method according to Embodiment 38, wherein the thermoplastic spinning formulation has an initial critical shear stress of about 100 kPa.

[0080] [Embodiment 40] The method of embodiment 38, wherein the starch-based polymeric material is included in an amount of at least 1 wt% of the spin formulation.

[0081] [Embodiment 41] The method of embodiment 38, wherein the starch-based polymeric material exhibits strain hardening characteristics.

[0082] [Embodiment 42] The method of embodiment 1, wherein the method comprises performing (b) such that the method comprises a method for melt blowing a composition comprising a starch-based polymeric material to produce fine fibers therefrom, the method comprising:

[0083] providing a composition comprising a starch-based polymeric material; and

[0084] melt blowing the composition to produce fibers comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity of no more than about 200 Pa s at 190 °C under a process shear rate of 200 s -1 and melt flow instability is avoided during the melt blowing process.

[0085] [Embodiment 43] The method of embodiment 42, wherein the composition exhibits a shear viscosity of no more than about 200 Pa s at 190 °C under a process shear rate of 200 s -1 and a shear viscosity of no more than about 85 Pa s at 190 °C under a spinneret shear rate of 1000 s -1 .

[0086] [Embodiment 44] The method of embodiment 42, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0087] [Embodiment 45] The method of embodiment 42, wherein the composition is a blend of the starch-based polymeric material and at least one thermoplastic polymer.

[0088] [Embodiment 46] The method of embodiment 45, wherein the at least one thermoplastic polymer comprises a polymer having a melt flow index greater than 500 g / 10 min, or from 1000 g / 10 min to 2000 g / 10 min, as measured at 230 °C under a load of 2.16 kg.

[0089] [Embodiment 47] The method of embodiment 45, wherein the at least one thermoplastic polymer comprises at least two grades of polypropylene, a first grade having a melt flow index of 1000 g / 10 min to 2000 g / 10 min as measured at 230 °C under a load of 2.16 kg, and a second grade having a melt flow index of no more than 100 g / 10 min as measured at 230 °C under a load of 2.16 kg.

[0090] [Embodiment 48] The method of embodiment 47, wherein the at least one thermoplastic polymer further comprises an additional grade of polypropylene having both isotactic structure and atactic structure, the polypropylene having a melt flow index of less than 1000 g / 10 min as measured at 230 °C under a load of 2.16 kg.

[0091] [Embodiment 49] The method of embodiment 42, wherein the starch-based polymeric material has a water content of no more than 2%, including any bound water.

[0092] [Embodiment 50] The method of embodiment 42, wherein the method produces fibers having a diameter of about 2 pm to about 10 pm.

[0093] [Embodiment 51] The method of embodiment 42, wherein the starch-based polymeric material is included in the composition in an amount of up to 60 wt%, up to 40 wt%, or 1 wt% to 35 wt%.

[0094] [Embodiment 52] The method of embodiment 42, wherein the starch-based polymeric material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

[0095] [Embodiment 53] A polymer blend for forming fine fibers by a melt-blowing process, the blend comprising:

[0096] a starch-based polymeric material having a water content of no more than 2%, including any bound water;

[0097] and

[0098] a thermoplastic polymeric material having an MFI of at least 500 g / 10 min as measured at 230 °C under a load of 2.16 kg, the MFI configured to plasticize the starch-based polymeric material;

[0099] wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.

[0100] [Embodiment 54] The blend of Embodiment 53, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0101] [Embodiment 55] The blend of Embodiment 53, wherein the starch-based polymeric material is included in an amount of 1 wt% to 35 wt% of the blend.

[0102] [Embodiment 56] The blend of Embodiment 53, wherein the blend exhibits a shear viscosity of no more than 85 Pa-s at 190 °C and 1000 s -1

[0103] [Embodiment 57] A melt-blown fine fiber suitable for use in making a nonwoven web, the fine fiber comprising:

[0104] a starch-based polymeric material, the starch-based polymeric material being present in an amount up to 35 wt%; and

[0105] a thermoplastic polymeric material, the thermoplastic polymeric material having a MFI of at least 500 g / 10 min as measured at 230 °C under a load of 2.16 kg, the MFI configured to plasticize the starch-based polymeric material;

[0106] wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material;

[0107] wherein the melt-blown fine fiber has a diameter of no more than about 10 pm.

[0108] [Embodiment 58] The fine fiber of Embodiment 57, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0109] [Embodiment 59] The fine fiber of Embodiment 57, wherein the fine fiber has a diameter of about 2 pm to about 4 pm.

[0110] [Embodiment 60] The fine fiber of Embodiment 57, wherein the thermoplastic polymeric material is itself non-biodegradable, and the starch-based material increases the biodegradability of the non-biodegradable thermoplastic polymeric material.

[0111] [Embodiment 61] The fine fiber of Embodiment 60, wherein at least 20% of the non-biodegradable thermoplastic polymeric material biodegrades within 3 years according to ASTM D-5338 or ASTM D-5511. ​

[0112] [Embodiment 62] The fine fiber according to Embodiment 60, wherein the fiber exhibits increased hydrophilicity, wettability, and / or absorbency compared to a fiber formed from polypropylene but not containing the starch-based polymeric material.

[0113] [Embodiment 63] The method according to Embodiment 1, wherein the method comprises performing (c) such that the method comprises a method for producing a yarn fiber from a composition comprising a starch-based polymeric material, the method comprising:

[0114] providing a composition comprising a starch-based polymeric material;

[0115] spinning the composition to produce a yarn fiber having a spun diameter of about 40 pm to about 150 pm, the yarn fiber comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity of no more than about 600 Pa-s at 190 °C under a process shear rate of 200 s -1 and melt flow instability is avoided during spinning of the yarn fiber; and

[0116] stretching the spun yarn fiber from its spun diameter to a smaller diameter.

[0117] [Embodiment 64] The method according to Embodiment 63, wherein the smaller diameter after stretching the yarn fiber is 10 pm to 50 pm.

[0118] [Embodiment 65] The method according to Embodiment 63, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having an average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0119] [Embodiment 66] The method according to Embodiment 63, wherein the composition is a blend of the starch-based polymeric material and at least one thermoplastic polymer.

[0120] [Embodiment 67] The method according to Embodiment 66, wherein the at least one thermoplastic polymer comprises a polymer having a melt flow index of 10 g / 10 min to 100 g / 10 min as measured at 230 °C under a load of 2.16 kg.

[0121] [Embodiment 68] The method according to Embodiment 66, wherein the starch-based polymeric material is provided in the form of a masterbatch, pre-blended with a first thermoplastic polymer, the method further comprising blending the masterbatch with a second thermoplastic polymer, wherein the first thermoplastic polymer and the second thermoplastic polymer have different melt flow index values.

[0122] [Embodiment 69] The method of embodiment 66, wherein the at least one thermoplastic polymer further comprises an additional grade of polypropylene having both isotactic structure and atactic structure, the polypropylene having a melt flow index of less than 1000 g / 10 min as measured at 230 °C under a load of 2.16 kg.

[0123] [Embodiment 70] The method of embodiment 63, wherein the starch-based polymeric material has a water content of no more than 2%, including any bound water.

[0124] [Embodiment 71] The method of embodiment 63, wherein the starch-based polymeric material is included in the composition in an amount of up to 60 wt% or up to 40 wt%.

[0125] [Embodiment 72] The method of embodiment 71, wherein the starch-based polymeric material is included in the masterbatch in an amount of up to 60 wt% and the starch-based polymeric material is included in the composition being spun in an amount of up to 40 wt%.

[0126] [Embodiment 73] The method of embodiment 63, wherein the starch-based polymeric material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

[0127] [Embodiment 74] A polymeric blend for forming a yarn fiber, the blend comprising:

[0128] a starch-based polymeric material having a water content of no more than 2%, including any bound water;

[0129] and

[0130] a thermoplastic polymeric material having a melt flow index of 10 g / 10 min to 100 g / 10 min as measured at 230 °C under a load of 2.16 kg, the melt flow index configured to plasticize the starch-based polymeric material;

[0131] wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.

[0132] [Embodiment 75] The blend of embodiment 74, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0133] [Embodiment 76] The blend of Embodiment 74, wherein the starch-based polymeric material is included in an amount of up to 60% by weight of the blend.

[0134] [Embodiment 77] The blend of Embodiment 74, wherein the thermoplastic polymeric material having a melt flow index of 10 g / 10 min to 100 g / 10 min comprises at least two thermoplastic polymeric materials, wherein a first has a melt flow index of about 10 g / 10 min to about 50 g / 10 min, and wherein a second has a melt flow index of about 75 g / 10 min to about 125 g / 10 min.

[0135] [Embodiment 78] A yarn fiber, comprising:

[0136] a starch-based polymeric material, the starch-based polymeric material being present in an amount of up to 60% by weight; and

[0137] a thermoplastic polymeric material, the thermoplastic polymeric material having a melt flow index configured to plasticize the starch-based polymeric material;

[0138] wherein the starch-based material is intimately dispersed within the thermoplastic polymeric material.

[0139] [Embodiment 79] The yarn fiber of Embodiment 78, wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol or at least 5 million g / mol.

[0140] [Embodiment 80] The yarn fiber of Embodiment 78, wherein the yarn fiber has a diameter of about 10 pm to about 50 pm.

[0141] [Embodiment 81] The yarn fiber of Embodiment 78, wherein the starch-based polymeric material is present in an amount of 1% to 40% by weight.

[0142] [Embodiment 82] The yarn fiber of Embodiment 78, wherein the thermoplastic polymeric material is itself non-biodegradable, and the starch-based polymeric material increases the biodegradability of the non-biodegradable thermoplastic polymeric material.

[0143] [Embodiment 83] The yarn fiber of Embodiment 82, wherein at least 20% of the non-biodegradable thermoplastic polymeric material biodegrades within 3 years according to ASTM D-5338 or ASTM D-5511.

[0144] [Embodiment 84] The yarn fiber according to Embodiment 78, wherein the fiber exhibits increased hydrophilicity, wettability, and / or absorbency compared to a fiber formed from polypropylene but not containing the starch-based polymeric material.

[0145] [Embodiment 85] The method according to Embodiment 1, wherein the method comprises performing (a) such that the method comprises a method for spinning a composition comprising a starch-based polymeric material to produce a spunbond nonwoven therefrom, the method comprising:

[0146] providing a composition comprising a starch-based polymeric material; and

[0147] melt spinning the composition to produce a fiber comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity of no more than about 300 Pa-s at 190 °C at a process shear rate of 200 s -1 and avoids melt flow instabilities during melt spinning.

[0148] Features of any of the above embodiments can be combined with each other in any combination.

[0149] While the NuPlastiQ starch-based polymers described herein are examples of starch-based materials that can provide the benefits described herein, it should be understood that the scope of the present invention extends broadly to other starch-based materials that can exhibit similar properties (e.g., developed at some time in the future), or even materials that can be synthesized from starting materials other than starch, that can achieve similar results due to the presence of the same or similar chemical structures or functional groups as the starch-based materials presently described. For example, if a material is synthesized (e.g., in a reactor) starting from a non-starch material that has a similar or identical chemical structure to NuPlastiQ, this is also within the scope of the present invention.

[0150] Other features and advantages of the present invention will become apparent to those of ordinary skill in the art upon perusal of the following detailed description of preferred embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0151] A more particular description of the application briefly described above will be rendered by reference to specific embodiments, which are illustrated in the appended drawings. It is to be understood that these drawings are only illustrative of the application and that the present application is not limited to the specific embodiments disclosed. The application will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0152] Figure 1 Viscosity versus shear rate (flow curve) is shown for sample 984, which is an exemplary high molecular weight starch-based polymeric material prepared as described in the Examples.

[0153] Figure 2 Flow curves are shown for various high molecular weight starch-based materials formed from different starting starch materials.

[0154] Figure 3 Additional flow curves are shown for other exemplary high molecular weight starch-based materials formed in accordance with the present application.

[0155] Figure 4 Data is shown regarding the melt flow instability characteristics of exemplary prepared high molecular weight starch-based materials.

[0156] Figure 5 Flow curves are shown for exemplary high molecular weight starch-based polymeric materials, along with a constant shear stress line of 100 kPa (at which instability of PP typically occurs).

[0157] Figure 6 Additional flow curves are shown, for example, for various additives (e.g., PP thermoplastic diluents having varying MFI values of 35 to 1600 g / 10 min).

[0158] Figures 7-7A Additional flow curve data is shown for various prepared and tested formulations.

[0159] Figures 8-9 Exemplary fibers are shown formed as described in the examples.

[0160] Figures 10-17 Various bicomponent fibers are shown formed as described in the examples.

[0161] Figure 18 Flow curves are shown at 190 °C for an exemplary formulation comprising 25% high molecular weight starch-based material, 50% 500 MFI PP, 21% 35 MFI PP, and 4% compatibilizer. Low shear data was obtained using a cone and plate rheometer.

[0162] Figure 19 Spinning envelopes are shown at 195 °C and 225 °C for exemplary polypropylene compositions (35 MFI and 100 MFI).

[0163] Figure 20 Rheotens plots are shown for various exemplary and comparative compositions.

[0164] Figure 21 An exemplary spunbond process is schematically shown.

[0165] Figure 22 An exemplary meltblown process is schematically shown.

[0166] Figure 23An exemplary yarn production process is schematically illustrated. DETAILED DESCRIPTION

[0167] I. DEFINITIONS

[0168] All publications, patents, and patent applications cited herein (whether supra or infra) are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference herein. This incorporation by reference is done solely to resolve any grievance of incoherence of this specification as opposed to applying the teachings of the applicants’ earlier patents.

[0169] The terms “comprising,” “including,” “containing,” or “characterized by” are synonymous and are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0170] The term “consisting essentially of’ limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed application.

[0171] As used herein, the term “consisting of’ does not include any element, step, or ingredient not specified in the claim.

[0172] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the application (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Thus, for example, a reference to “a starch” can include one, two, or more starches.

[0173] As used herein, “nonwoven” refers to a fabric-like material made from staple fibers and / or long fibers that are bonded together, for example, by thermal, mechanical, chemical, or solvent treatment. Such materials are neither woven nor knitted, but are formed from a web of such fibers that are entangled or otherwise bonded together.

[0174] All percentages, ratios, parts, and amounts described herein are by weight unless otherwise indicated, including molecular weight— i.e., weight average molecular weight and number average molecular weight.

[0175] As will be understood by those of ordinary skill in the art, the numbers, percentages, ratios, or other values stated herein can include that value and other values about or approximately that value. Thus, the values stated herein should be construed to be sufficiently broad as to encompass at least the value stated, and / or a value that is rounded to the value stated. The stated values include at least variations expected due to typical manufacturing processes, and can include values within 25%, within 15%, within 10%, within 5%, within 1%, etc. of the stated value.

[0176] All numbers expressing quantities of ingredients, constituent, conditions, or related values are understood to be modified in all instances by the term "about" as per the context in which they are used. Numerical ranges include all values from and including the lower and the upper values, in increments of one unit provided that there is a context for the use of such values. Although the numerical ranges and parameters setting forth the broad scope of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0177] Some ranges are disclosed herein. Other ranges can be defined as examples of particular parameters. All such ranges are contemplated and are within the scope of the disclosure. Furthermore, the recitation of values herein is intended to serve as a shorthand method of referring individually to the minimum and maximum values of each element. Unless otherwise stated, each individual value is incorporated into the specification as if it was individually recited herein.

[0178] The phrase "free of" or like phrases as used herein means that the composition contains 0% of the component in question, i.e., the component is not intentionally added to the composition. However, it is understood that such components can be formed incidentally, can be present incidentally in another included component, e.g., as an incidental contaminant, etc., where appropriate.

[0179] The phrase "substantially free of" or like phrases as used herein means that the composition preferably contains 0% of the component in question, but it is understood that there can be very low concentrations present, e.g., by incidental formation, incidental contamination, or even intentional addition, if any. If present, such components can be present in an amount of less than 1%, less than 0.5%, less than 0.25%, less than 0.1%, less than 0.05%, less than 0.01%, less than 0.005%, or less than 0.001%.

[0180] As used herein, the term "non-biodegradable" with respect to a material means that the natural material (without additives added to make it biodegradable) does not degrade (particularly biodegrade) to a significant extent into, e.g., carbon dioxide and / or methane, within a reasonably finite period of time (e.g., one year, 2 years, 3 years, or 5 years) when exposed to various typical disposal conditions such as in the ocean, in a landfill, industrial or other composting conditions, or to specific ASTM conditions intended to evaluate the biodegradability under specific conditions (e.g., ASTM D-5511, D-5526, D-5338, D-6691). However, it is understood that given sufficient time and exposure to sunlight, oxygen, and degrading microorganisms, most polymeric materials (e.g., even those typically considered to be "non-biodegradable") will eventually degrade or even biodegrade to some limited extent over an extended period of time (e.g., centuries).

[0181] As used herein, the term "biodegradable" with respect to a material means that the material described herein is significantly biodegraded (e.g., more than 50%) to base molecules, such as carbon dioxide, methane, and / or water, by the action of appropriate microorganisms within a reasonably finite time frame (e.g., 5 years, 3 years, 2 years, 1 year, etc.) under "ideal" biodegradation conditions (e.g., anaerobic digesters, industrial composting, etc.), such as under the conditions of various ASTM biodegradation tests (e.g., ASTM D-5511, D-5526, D-5338, or D-6691).

[0182] The term "modified" as used, for example, in describing "modified starch" and the like, refers to physical and / or chemical modifications, including the conversion of a starting starch material to a material having a lower molecular weight. Applicant's NuPlastiQ materials can be considered to comprise "modified" starch. Starches that can not necessarily fall within the description of the term "modified" can also be suitable, for example, insofar as they otherwise exhibit properties as described herein. Such mechanical and / or chemical modifications can include the modification of amylopectin components to more linear amylose structures.

[0183] By way of example, some of the literature can suggest that amylose (15-30% of the starch units) can contain chains of about 40,000 and 340,000 Daltons in molecular weight, where the chains contain 250 to 2000 anhydrous glucose units. Amylose is an unbranched chain that is coiled in a helical shape.

[0184] Amylopectin (70-85% of the starch units) contains chains of up to 80,000,000 Daltons in molecular weight. The foregoing descriptions of amylose and amylopectin are merely exemplary, and it will be understood that starches having different properties can also be suitable for use.

[0185] The descriptions herein are merely exemplary, and it will be understood that a variety of modifications or variations to such starch components are possible. Applicant's NuPlastiQ materials as described herein are examples of modified starch-based materials having very high molecular weights that are available from Applicant. Determination of molecular weight can be by any desired method, for example, any of various size exclusion chromatography techniques (e.g., gel permeation chromatography ("GPC") or gel filtration chromatography ("GFC")).

[0186] Melt flow index values are in g / 10 min at standard conditions (e.g., 230 °C under a load of 2.16 kg for polypropylene, or 190 °C under a load of 2.16 kg for polyethylene and other materials), unless otherwise indicated.

[0187] With respect to various standardized tests (e.g., ASTM or other tests), it will be understood that, unless otherwise indicated, a reference to any such standard refers to the most recent update of such standard, if any. Any such referenced standard is incorporated by reference herein in its entirety.

[0188] II. INTRODUCTION

[0189] The present disclosure relates, among other things, to methods for successfully spinning (e.g., spunbond, meltblown, yarn, or similar spinning processes) compositions comprising starch-based polymeric materials, which can have very high molecular weights. In one embodiment, the starch-based polymeric material can have a relatively high molecular weight, for example, greater than 2 million, 3 million, 4 million, or 5 million, such as at least 3 million to 20 million or 5 million to 16 million. Such values can represent weight average molecular weight. Number average molecular weight can be greater than 1 million, 2 million, 3 million, 4 million, or 5 million, such as 3 million to 12 million, 3 million to 10 million, or 5 million to 7 million. The starch material forming the starch-based polymeric material (e.g., from starch and plasticizer in a reactive extrusion process) can similarly have a weight average molecular weight of greater than 1 million, 2 million, 3 million, 4 million, or 5 million, such as 3 million to 10 million or 5 million to 7 million. The ratio of Mw to Mn (polydispersity) of the starting starch or finished starch-based polymeric material can be at least 1 or greater than 1, for example, 1 to 2, 1 to 3, 1 to 4, or even higher.

[0190] For example, to be suitable for use in a spunbond process, the composition needs to be capable of being spun into fine fibers, for example, having a diameter of no more than 30 pm, for example, no more than 25 pm. Of course, the processes of the present invention are also suitable for forming larger fibers, up to any desired size. For example, up to 50 pm, up to 100 pm, or even larger sizes, should be desired. Meltblown fibers have even more stringent fiber size requirements, for example, typically less than 5 pm in diameter (e.g., 2 pm to 10 pm or 2 pm to 4 pm). By way of example, yarn fibers can initially be formed at 40 pm to 150 pm or 40 pm to 100 pm (e.g., about 60 pm), with the spun yarn subsequently drawn (e.g., heat drawn) to a smaller size, for example, 10 pm to 50 pm or 10 pm to 30 pm (e.g., about 20 pm). The present disclosure describes formulations and processes that can be used for any such processes.

[0191] Even though NuPlastiQ as intended grade of a starch-based polymeric material can have a very high molecular weight (e.g., at least 3 million, 3 million to 10 million, 5 million to 7 million, 7 million to 9 million, or even 10 million to 18 million), Applicants have surprisingly discovered that, at least in part due to certain characteristics exhibited by such material, it is possible to spin fibers that contain a significant portion of such high molecular weight material. For example, even though such starch-based material exhibits a very high molecular weight (and thus exhibits an extremely high zero shear viscosity (Eta-0, η0) as well as a corresponding high shear viscosity η s and elongation or extensional viscosity η E ), Applicants have discovered that such material exhibits characteristics that allow it to still be spun even under process conditions achievable in commercial spunbond, meltblown, or yarn production lines, with particular selection of operating parameters and composition formulation. For example, Applicants have discovered that such starch-based material exhibits excellent shear sensitivity, such that even though the zero shear viscosity can be extremely high (e.g., greater than 10 6 Pa-s or 10 7 Pa-s, which is about at least one order of magnitude higher than conventional TPS materials), the shear viscosity can rapidly decrease under commercial line shear rates (e.g., 200 to 1500 s -1 ), particularly in connection with other “handles” or “levers” that can be adjusted, as described below.

[0192] For example, in addition to excellent shear sensitivity, it has been discovered that the starch-based polymeric material exhibits excellent responsiveness to thermoplastic diluent plasticizers, with the addition of polypropylene or similar thermoplastic polymer having a higher melt flow index significantly improving the flow characteristics. The MFI or other characteristics of the diluent selected for dilution and plasticization of the starch-based polymeric material so as to be spinnable under conditions as described herein can depend on whether the process is a spunbond process, a meltblown process, a yarn process, or other melt extrusion fiber spinning process. For example, different diluents can be selected depending on the particular process employed.

[0193] Additionally, the starch-based material exhibits excellent responsiveness to extrusion temperature, in that the material exhibits a significant decrease in viscosity as the extrusion temperature is increased. Thus, by providing spinning conditions in which the extrusion temperature is within a particular selected range (e.g., 170°C to 230°C, 175°C to 225°C, 180°C to 200°C, or 180°C to 195°C), at a given process shear rate with a given spinneret shear rate (e.g., about 200 s -1), and wherein an effective amount of the higher melt flow index thermoplastic material is compounded with the starch-based polymeric material to further plasticize the blend, enabling the composition to be processed through a given system while avoiding melt flow instability. The actual shear rate varies based on the die diameter, flow rate (e.g., GMH: grams per minute per hole), and material density. Generally, the spinneret shear rate can range from 400 to 10,000 s -1 under various yarn, spunbond, meltblown, or similar melt-extruded fiber spinning processes.

[0194] By way of example, in a spunbond or meltblown process, the composition can exhibit a shear viscosity of no more than about 125 Pa-s or no more than 95 Pa-s (e.g., no more than 50 to 65 Pa-s) at 1000 s -1 Under such conditions, spunbond fibers can be produced, for example, having a diameter of at least 10 pm, such as 15 to 100 pm, 10 to 50 pm, or 15 to 30 pm. By selecting an appropriate diluent plasticizer, meltblown fibers can be produced, for example, having a diameter of 5 pm or less, such as 2 to 10 pm or 2 to 4 pm. By selecting an appropriate diluent plasticizer, yarn fibers can be produced, for example, having a diameter of 40 pm or greater, such as 40 to 150 pm, 40 to 100 pm, 40 to 80 pm, such as about 60 pm, which can be drawn to a smaller final diameter (e.g., 10 to 50 pm, 10 to 30 pm, such as about 20 pm) in a heated draw roll typically used in a yarn process after initial fiber formation. Of course, spunbond, meltblown, and yarn processes are merely exemplary, and other similar fiber spinning processes can be used, producing a variety of diameter fibers using the principles detailed herein.

[0195] In any event, it is surprising that such a“handle” or“lever” is sufficient to enable fiber spinning with compositions containing a substantial portion of very high molecular weight starch-based polymeric material. This is possible even without the addition of a strain hardening additive to the composition specifically. For example, Applicants have further observed that the starch-based polymeric material employed in the present consideration appears to be strain hardening on its own, rather than strain thinning like other thermoplastic starch materials.

[0196] Examples of suitable high molecular weight starch-based materials are available under the trade designation "NuPlastiQ" from BioLogiQ, particularly those having very high molecular weights as described herein. Some properties of NuPlastiQ materials, particularly NuPlastiQ GP and NuPlastiQ CG, are described in Applicant's other U.S. applications (e.g., U.S. Application No. 16 / 925,705 (21132.27.1.1)), which are incorporated by reference herein in their entirety. Many of the properties of the high molecular weight starch-based materials described herein can be similar to those previously described with respect to NuPlastiQ GP and NuPlastiQ CG. Other starch-based polymers can also be suitable for use, for example, where such materials can exhibit at least some of the other key properties described herein that enable the spinning of such materials.

[0197] At least in the case of using any of the various NuPlastiQ grades as the starch-based material, the biodegradability of the resulting blend is improved and / or accelerated. For example, in a polymer / NuPlastiQ blend that includes a polymer such as polypropylene or polyethylene that has heretofore been considered non-biodegradable, a substantial portion or all of the carbon atoms in the blended product (including those in the PP and PE) can be converted more quickly by microorganisms into CO2and / or CH4. In other words, NuPlastiQ can make polypropylene and polyethylene biodegradable when blended with polypropylene and polyethylene, forming a homogeneous mixture in which the NuPlastiQ is intimately dispersed in the polypropylene and polyethylene. Additionally, when blended with polymers such as PLA or other polymers (e.g., PBAT, PBS, PCL, PHA, etc.) that have heretofore been considered compostable or biodegradable, the rate and / or extent of biodegradation of such other polymers can be further improved by the addition of the NuPlastiQ starch-based material under any given conditions. The rate of conversion by microorganisms depends on several factors, such as the thickness of the structure, the other form of the article (e.g., ground powder versus larger continuous pieces), the number of microorganisms, the type of microorganisms, the environmental conditions (e.g., pH, moisture, temperature, etc.), the ratio of NuPlastiQ starch-based material to other polymers in the product, the type of plastic in the blend, the strength of the carbon bonds in the plastic, etc.

[0198] Accordingly, embodiments of the present application allow for the formation of fine fibers from high molecular weight starch materials, for example, as used in spunbond processes, melt blown fiber processes, yarn or other fiber melt spinning processes, by blending very high viscosity starch materials (e.g., having viscosity characteristics that can be at least one order of magnitude greater than previously described starches used for fine fiber formation) with a thermoplastic diluent polymer material to ensure that the desired rheological characteristics are obtained (e.g., to keep the shear stress below a critical threshold value) to allow such starch compositions to be advantageously incorporated into fibers that would otherwise be formed from conventional thermoplastic materials when such compositions are processed through a spinneret at commercial production line shear rates, thereby improving the sustainability characteristics of such fibers and nonwovens formed therefrom.

[0199] In addition to providing such formulations with increased sustainable bio-content, embodiments of the present application are directed to providing such products (e.g., compositions, fine fibers, nonwoven fiber webs formed therefrom, and any articles incorporating such fiber structures) with one or more mechanical or physical advantages associated with the inclusion of starch-based polymeric materials within the composition. For example, the incorporation of the presently contemplated starch-based materials can actually increase the critical shear stress threshold characteristics of the thermoplastic polymeric materials with which they are compounded or blended, for example, providing additional flexibility to the manufacturer in terms of the parameters used in a spunbond, melt blown, yarn or similar fiber production process using conventional resins. For example, a typical polypropylene composition exhibits a critical shear stress of about 100 kPa, beyond which threshold melt flow instabilities occur that make it impossible to effectively spin usable fibers under conditions that exceed the critical shear stress. The high molecular weight starch-based polymeric materials of the present application can actually increase the applicable critical shear stress threshold, thereby allowing the composition to be effectively processed at higher shear stresses, for example, up to about 125 kPa, 150 kPa, or even 200 kPa, depending on how much high molecular weight starch-based material is added to the formulation. This is a significant advantage, thereby potentially allowing for the production of finer fibers, faster line speeds, etc.

[0200] Finally, in addition to providing the possibility of bicomponent or other multi-component fiber geometries, the present disclosure can provide unusual fiber morphological characteristics, for example, fibers having a "bump" provided thereon, where such bump can comprise or consist essentially of a starch component (or another component of a composite blend forming the fiber). For example, for fibers having a thickness ("diameter") of 15 pm to 30 pm, such bump can vary from the normal, generally circular fiber radius or diameter (i.e., in their radius or thickness) by 1 pm to 4 pm.

[0201] III. EXEMPLARY ARTICLES AND METHODS

[0202] The blends and processes of the present invention can include one or more thermoplastic polymer materials having a melt flow index configured to act as a diluent for the starch-based polymer material. Polypropylene is one example of such a material, although other thermoplastic polymers can also be suitable. By way of example, the selected thermoplastic polymer can have a melt flow index (MFI) of at least 35 (e.g., 35 to 2000, such as 35 to 1750, 35 to 1550, 35 to 1250, 35 to 1000, 35 to 750, or 35 to 500). For polypropylene, such MFI values can be at 230°C with a load of 2.16 kg. For polyethylene, such MFI values can be at 190°C with a load of 2.16 kg. The MFI or other properties of the diluent material employed can depend on whether the formulation is for a spunbond, meltblown, yarn, or other fine fiber extrusion / spinning process, with the formulation selected to have the rheological properties required to ensure a sufficiently low shear viscosity (e.g., BPI as described herein, at 190°C using a 1 mm diameter die with L / D = 30, at 200 s -1 downstream measurements) to pass the formulation through the system, and the formulation has a viscosity that avoids melt flow instability, particularly through the high shear conditions associated with the spinneret. In one embodiment, more than one such diluent material can be used, e.g., a thermoplastic polymer material having a melt flow index of 35, and another material having a melt flow index of 100 to 2000, 100 to 1750, 100 to 1550, 100 to 1250, 100 to 1000 (e.g., 100 to 500 or 400 to 600, etc.). In one embodiment, a first diluent material can be pre-blended with the starch-based polymer material, e.g., in a NuPlastiQ or other masterbatch. Such a first diluent material included in the masterbatch can have a relatively low MFI value, e.g., no more than 200, or no more than 100, such as 35 to 100. Such a masterbatch can be blended with a second diluent material at the time of processing, with the second diluent material selected according to the process to be employed (e.g., spunbond, meltblown, yarn, etc.). In one embodiment, the second diluent material can have a higher MFI value than the first diluent material. Of course, a fully diluted composition can also be provided without the use of any intermediate masterbatch.

[0203] While polypropylene is an example of a particularly suitable material for use in such processes, other thermoplastic materials can also be suitable for use, for example, including but not limited to polyethylene, other polyolefins, polyesters such as PLA, PBAT, and the like. For example, some polyesters can be particularly suitable for use in forming the yarn fibers. As described herein, examples of suitable thermoplastic materials can have an MFI value that is greater than the MFI value of the starch-based polymeric material. Such MFI values are typically recorded in units of g / 10 min under standard conditions (e.g., ASTM D-1238 or other relevant standards). Such values are higher than the melt index of the starch-based polymer. By way of example, the MI of the exemplary high molecular weight NuPlastiQ material shown in Table 1 is 6 g / 10 min at 170 °C under a load of 21.6 kg. Such materials are very viscous, exhibiting little flow under standardized testing conditions. In fact, it is very difficult to measure MFI using the standard 2.16 kg weight at the standard temperature of 190 °C, because the value is very low, and because any such flow can be due in significant part to degradation of the NuPlastiQ material under such conditions, such that any measured value can be very inconsistent. Because the NuPlastiQ material is stable and consistent, it can be accurately measured at 170 °C under a higher load of 21.6 kg, which is the reporting condition for the value shown in Table 1.

[0204] Thermoplastic materials used as diluents to improve the rheological properties of the starch-based material can be derived from conventional petrochemical “fossil fuel” sources, or from so-called “green” or renewable sources (e.g., bioPE, bioPET, PLA, other polyesters, etc.). Various analytical methods can be used to distinguish petrochemical fossil fuels from renewable resources from one another, for example, one of which can involve determining the ratio of C 14 to C 12 in the material. By way of example, petrochemical fossil fuel sources contain no C 14 content, while materials derived from renewable or sustainable materials (renewable and sustainable are used interchangeably herein) (even the same material, such as “green” PE versus conventional fossil fuel PE) will exhibit a C 14content (e.g., potentially 1 in 1 trillion carbon atoms). Of course, other analytical methods exist for identifying and distinguishing between two different sources of material (fossil fuel derived versus renewable source). Those of ordinary skill in the art will appreciate that renewable materials are derived from starting materials that can be replenished after production (e.g., renewed in about 100 years or less), as opposed to fossil fuel sources (which take at least tens of thousands of years to form). Examples of such renewable source materials include various plant crops, such as various plant starches, sugar cane, corn, or other plant products. Starch-based polymeric materials and thermoplastic diluent materials having the desired MFI properties can be provided in any desired form, such as pellets, powders, blobs, slurries, and / or liquids.

[0205] The compositions of the present application can be used to form fine fibers for making any desired article of manufacture by any of a variety of fine fiber melt spinning processes. Examples of such processes include, but are not limited to, various spunbond, meltblown, yarn, and other processes, the details of which will be apparent to those skilled in the art. Such fine fibers can be used to produce various nonwoven structures or carded fibers (e.g., in the case of yarns), and the like. Fine fibers can also be produced and wound, and then provided as an intermediate material from which a fabric or other article of manufacture can be formed. Such fabrics can be nonwoven or woven or knitted, and the like. It will be apparent that fine fibers comprising starch-based polymeric materials as described herein can have a variety of uses. When the composition comprises a starch-based polymeric material as well as one or more thermoplastic polymeric materials having particularly desirable melt flow index properties, such components can be compounded together prior to spinning (e.g., with or without the use of compatibilizers). By way of example, all of the materials can be compounded together in advance, and then fed into an extruder.

[0206] In one embodiment, the starch-based material can be provided in the form of a masterbatch that already includes a thermoplastic diluent material, and optionally a compatibilizer. The masterbatch can be blended with additional thermoplastic diluent material in the same process in which the spinning is performed in an extruder. For example, the masterbatch can include the starch-based polymeric material, a compatibilizer, and a first thermoplastic diluent material having a desired MFI value. This masterbatch can then be further blended with another or additional thermoplastic polymeric diluent material (e.g., having a desired MFI) prior to spinning. It will be apparent that there are many possibilities for such blending or compounding. When the final blending or compounding occurs in the spinning process, for example, one or more thermoplastic polymers having particularly selected melt flow index characteristics and the starch-based material can be fed into the extruder (e.g., into one or more hoppers thereof). The different materials can be fed into the extruder at approximately the same time (e.g., through the same hopper) or at different times (e.g., through different hoppers, one being introduced into the extruder along the screw earlier than the other, into the same chamber, different chambers, etc. It will be apparent that there are many possibilities for such processing.

[0207] It will be apparent that many blending possibilities are possible. In one embodiment, any provided masterbatch including a starch-based material can already include at least a portion of one or more thermoplastic polymers having particularly selected melt flow index values. For example, where the thermoplastic polymer includes two or more different polymers having different melt flow index values (e.g., 35 and 500, or 100 and 500, or 35 and 1550, etc.), the masterbatch can already include one such thermoplastic polymer that has been compounded with the starch-based material. A compatibilizer can also typically be present in such a masterbatch. By way of example, where the final composition for the spun fine fibers is intended to include 25 wt% starch-based polymer, 4 wt% compatibilizer, and 71 wt% thermoplastic polymer having a particular melt flow index value, the masterbatch can include 50 wt% starch-based material, 8 wt% compatibilizer, and 42 wt% one or more thermoplastic polymers. By way of example, the masterbatch can then be blended with additional thermoplastic polymer having a particularly desired melt flow index value in a 1 : 1 (or other blending ratio) to obtain the final composition from which the fine fibers are spun.

[0208] An important property of the compositions of the present invention can be that the selected starch-based material has a high molecular weight, higher than many starch-based materials previously described as suitable for use in the spinning of fibers. For example, previous work incorporating starch-based materials into fibers has focused on efforts to increase the amylose content of the starch-based material (e.g., by enzymatic debranching), or otherwise reduce the molecular weight of the starch-based material, such that it has rheological properties that allow the composition to be spun. Even with such modifications, U.S. Publication 2019 / 0330770 notes that while such a blend can be spun, the rheological properties of such a blend are still incompatible with manufacturing processes that operate at commercial line speeds (e.g., 500 m / min - 1000 m / min or higher), at commercial shear rates, and if the production line is operated at such speeds, the fibers will break, where such a starch-containing composition is used. Such adjustments to reduce line speeds can also actually reduce the strength of the fibers formed, which of course is not desirable. Additionally, the compositions described in such previous attempts can variably include significant water content. While it can be difficult to remove such residual water content (which is present in as much as bound water, bound to the starch molecules), the residual presence of water can undesirably affect various material properties or otherwise be undesirable. In contrast to these previous attempts to retain bound water, in at least some embodiments as contemplated herein, the water content of the high molecular weight starch-based material is minimal, e.g., no more than 2%, or no more than 1.5%, even including any bound water.

[0209] Using the same reactive extrusion process as previously obtained for the commercially available NuPlastiQ grades, applicants have now prepared a high molecular weight NuPlastiQ material, which they have demonstrated can be incorporated into a composition suitable for the spinning of fine fibers. Such NuPlastiQ materials suitable for fine fiber spinning are available from applicants. In any event, the starch-based polymeric materials described and contemplated by the present invention exhibit significantly higher molecular weight values than any of the previously shown spinnable starch-based materials. Previous attempts in the literature to spin fine fibers from compositions including starch-based materials have only been successful in spinning such fibers where the starch-based component has a molecular weight (weight average molecular weight) of up to about 1 million, sometimes to possibly as high as 2 million. For example, Star Dri-100, used in many such examples in the literature, has a molecular weight of only about 21,000, as measured using the same gel permeation chromatography used for the molecular weight measurements of the starch-based polymeric materials described herein.

[0210] As some outliers in the art, U.S. Publication 2019 / 0330770 reports examples including the use of starch-based materials having a molecular weight of 2.9 million, where the content of starch does not exceed 30 wt% of the blend, although the applicants are unaware of compositions comprising a significant portion (e.g., at least 1%, at least 3%, at least 5%, at least 10%, at least 15%, or at least 20%) of starch-based polymeric materials having a significantly higher weight average molecular weight (e.g., at least 3 million, 4 million, or 5 million Daltons) that have successfully spun fibers. This is not surprising because viscosity rises exponentially with molecular weight, and compositions having very high viscosity are poor candidates for fine fiber spinning. For example, at least one of the inventors herein believes that it is not possible to spin fine fibers from compositions comprising a significant portion of high molecular weight starch-based polymeric materials described herein (see, e.g., Tables 3A-3B), particularly at commercial line speeds where the shear rate and applied shear stress are close to the critical values at which melt instability occurs. The present disclosure describes how this is accomplished.

[0211] The starch-based material can be formed from one or more starches from one or more plants, such as corn starch, tapioca starch, cassava starch, wheat starch, potato starch, rice starch, seaweed starch, sorghum starch, and the like. In some embodiments, a mixture of different types of starch can be used, as described in the applicant’s earlier applications, which have been incorporated by reference herein. In other embodiments, only a single starch can be used in forming the starch-based material. In addition to starch, the starch-based material is typically formed with a plasticizer. In one embodiment, the material forming the starch-based polymeric material can consist essentially of starch and plasticizer. Additional components can optionally be included, such as an odor reducing agent or other adjunct. The use of odor reducing agents (e.g., vanillin) is described in the applicant’s U.S. Patent 10,920,044 (21132.12.1), which is incorporated by reference herein in its entirety. Once the starch-based polymeric material is formed from starch and plasticizer, a compatibilizer or other adjunct can be compounded into a masterbatch comprising the starch-based polymeric material and a thermoplastic diluent polymer (e.g., polypropylene having a selected MFI value).

[0212] The starch-based material can be formed largely from starch. For example, at least 65%, at least 70%, at least 75%, or at least 80% by weight of the starch-based material can be attributable to one or more starches. In one embodiment, 65% to 90% by weight of the finished starch-based material can be attributable to one or more starches. Except for a negligible water content (e.g., no more than 1.5-2%), the balance of the finished starch-based material can be or attributable to a plasticizer (e.g., glycerol). Where an odor-reducing agent is included, the odor-reducing agent is typically included in very small amounts (e.g., less than 1%, often much less than 0.1%, such as 1 ppm to 100 ppm, or 1 ppm to 10 ppm). The above percentages can represent the percentage of starch relative to the starting materials from which the starch-based material is formed, or that portion of the finished starch-based material that is derived from or attributable to the plasticizer (e.g., at least 65% of the starch-based material can be attributable to (formed from) starch as a starting material). The balance can be attributable to the plasticizer.

[0213] By way of example, the materials from which the starch-based material is formed can include at least 12% by weight, at least 15% by weight, at least 18% by weight, at least 20% by weight, at least 22% by weight, no more than 35% by weight, no more than 32% by weight, no more than 30% by weight, no more than 28% by weight, or no more than 25% by weight of a plasticizer. Such percentages can represent the portion of the finished starch-based material that is derived from or attributable to the plasticizer.

[0214] Exemplary plasticizers include, but are not limited to, glycerol, polyethylene glycol, sorbitol, polyol plasticizers, hydrogen-bonding organic compounds that do not have hydroxyl groups, acid anhydrides of sugar alcohols, animal proteins, plant proteins, fatty acids, phthalates, dimethyl succinate and diethyl succinate and related esters, glyceryl triacetate, glyceryl monoacetate and diacetate, glyceryl monopropionate, dipropionate and tripropionate, butyric acid esters, stearic acid esters, lactic acid esters, citric acid esters, adipic acid esters, stearic acid esters, oleic acid esters, other acid esters, or combinations thereof. Glycerol can be particularly effective.

[0215] The finished starch-based polymeric material can comprise no more than 5 wt%, no more than 4 wt%, no more than 3 wt%, no more than 2 wt%, no more than 1.5 wt%, no more than 1.4 wt%, no more than 1.3 wt%, no more than 1.2 wt%, no more than 1.1 wt%, or no more than 1 wt% water, including bound water. By way of example, patent references generally describing the modification of starch-based polymeric materials for use in spinning include significant amounts of bound water (e.g., 5-16%), which is significantly higher than the water content typically present in the starch-based materials presently contemplated. Moreover, while lower water contents are described in some references generally describing starch-based polymeric materials (e.g., for forming films), there is no effort to modify such materials for use in spinning, and simply swapping one such material for another is not a simple operation due to the very demanding specifications required for such materials, particularly where the materials that have been specifically formed to be spinnable include significant water content.

[0216] Other details relating to the starch and glycerol or other plasticizer portions used to form the starch-based materials are described in the Applicant’s other patent applications, which have been incorporated by reference herein. The physical properties of NuPlastiQ GP are shown in Table 1 below. The properties of the high molecular weight starch-based polymers used herein for spun fine fibers are similar to those shown in the table. By way of example, the properties of density, glass transition temperature, tensile strength, Young’s modulus, elongation at break, dart impact, and water content can be representative of the high molecular weight starch-based polymeric materials contemplated for use in embodiments of the present application. As will be appreciated by those skilled in the art, any of such properties can be measured by any of a variety of ASTM or other standards. Some properties can vary somewhat from the values shown in Table 1 (e.g., ±25% or ±10%).

[0217] Table 1

[0218]

[0219] The weight average molecular weight can be relatively high, as described herein, such as greater than 2 million, greater than 3 million, greater than 4 million, greater than 5 million, such as 3 million to 20 million, 5 million to 18 million, or 5 million to 16 million. Such values can be determined by any of various suitable size exclusion chromatography (e.g., GPC and / or GFC). The values in the examples herein were determined by size exclusion chromatography using multi-angle light scattering (MALS) and refractive index (RI) detection. In any event, such molecular weight values are significantly higher than starch-based materials that have been made spinnable previously. The starch that is made into the starch-based polymeric material can similarly have a very high molecular weight as described herein. That is, it should be understood that in other embodiments, a starting starch or finished starch-based polymeric material having a lower weight average molecular weight, such as less than 2 million or possibly even less than 1 million, can be used. Viscosity is closely related to molecular weight. Due to the high molecular weight, the starch-based materials presently contemplated also exhibit viscosity characteristics that are significantly higher than starch-based materials that have been used in spun fibers heretofore. For example, the zero shear viscosity, even at a given process temperature (e.g., 170°C - 195°C) or other relevant temperature, can be at least an order of magnitude greater than starch-based materials that have been used in spinning heretofore.

[0220] While some properties can be similar to other thermoplastic starch materials, other properties can be substantially different than typical starch-based materials. For example, the density of the NuPlastiQ material is particularly high, such as greater than 1 g / cm 3 , at least 1.1 g / cm 3 , at least 1.2 g / cm 3 , or at least 1.25 g / cm 3 (e.g., 1.4 g / cm 3 , as shown in Table 1 above). Various other characteristics can also be substantially different than superficially similar starch-based polymeric materials. As noted above, the water content of the NuPlastiQ material is low. When this material absorbs moisture, it exhibits plastic behavior and becomes pliable. When removed from a humid environment, the material dries and becomes stiff again (e.g., exhibits a water content of less than about 1.5% again). Any moisture present in the NuPlastiQ (e.g., in pellet form) can be released as steam during processing. Thus, fine fibers, nonwoven webs, or other articles produced from the contemplated starch-based materials can exhibit even lower water content, as the thermoplastic diluent material will typically not contain water or contain negligible water, and substantially all of the water in the starch-based polymeric material can be released during the manufacture of the desired article.

[0221] Low water content in any starch-based material can be important as significant water content can interfere with the ability to process the composition at elevated temperatures. While applicants have observed relatively hydrophobic properties of films comprising blends of NuPlastiQ (e.g., as determined by Dyne Pen testing), the composite fibers of the present invention appear to exhibit more hydrophilic properties, which can be advantageous for applications in which wettability or absorbency would be desirable (e.g., diapers, feminine pads, etc.). Such properties have been observed for fibers comprising 25% NuPlastiQ, and can be provided in fibers comprising more or less NuPlastiQ within any of the ranges described herein.

[0222] When the hydrophobicity of the materials that can be included in a multi- component or bi-component (i.e., "bico") fiber differ, it is of course also possible to separate the phases or components in a multi-component or bi-component (i.e., "bico") fiber, where the sheath can be one composition and the core is another composition. Other bi-component geometries are of course also possible, and can similarly provide for differences in composition in different fiber component geometries (e.g., fan cake fibers, island-in-the-sea fibers, etc.). In such bi-component fibers, one or both locations (e.g., sheath vs. core, island vs. sea, etc.) can include a starch-based polymeric material, while the other location can similarly have desired compositional properties (e.g., it can include a greater or lesser portion of starch-based material than the other bi-component fiber location, or it can not include a starch-based material at all).

[0223] It is particularly advantageous to be able to form bi-component fibers in which at least one of the geometries of the bi-component fiber (e.g., sheath, core, etc.) includes a starch-based polymer. For example, it is surprising and advantageous that the very high viscosity starch-based materials of the present invention can be extruded through small diameter spinneret dies to form uniform standard fibers as described herein. It is even more surprising that such very high viscosity starch-based materials can be extruded through even thinner geometries, such as those associated with sheath / core or other bi-component fiber geometries. Figures 10-17 FIGS. 1-3 show diagrams showing the formation of such sheath / core bi- component fibers having a starch-based material in the core and a thermoplastic sheath (e.g., PP or PLA). In other embodiments, the location of the materials can be reversed, e.g., the starch-based polymer can be present in the sheath and the thermoplastic in the core, or the starch-based material can be present in both portions (e.g., at different ratios to the thermoplastic in each).

[0224] The low water content in NuPlastiQ materials is not achieved through esterification or etherification, which is common in some other TPS materials that can include relatively low water content. Such esterification or similar modifications can be expensive and complex. Further, the NuPlastiQ materials, as an example of a starch-based material useful herein, have undergone mechanical, physical, or chemical reactions and / or changes as compared to the starting starch and glycerol materials. For example, the starch-based material can be the product of a reactive extrusion process, for example, under pressure at an extrusion temperature as described herein. The finished starch-based material can not be considered to be a simple mixture including native starch and glycerol, but rather has undergone chemical and / or physical changes, including changes in molecular weight relative to the starting starch material. The low water content achievable in the starch-based material can be due at least in part to the physical or chemical change of the starch and plasticizer materials into a starch-based thermoplastic polymer, which does not retain water as well as native starch or other conventional thermoplastic starch materials. Additionally, NuPlastiQ materials resist recrystallization or retrogradation, which is common for many other thermoplastic starches. For normal thermoplastic starches, they exhibit a tendency to "retrograde," which manifests as their recrystallization over time from a relatively amorphous state back to a more crystalline state - which is the natural state of native starch powder. Most thermoplastic starches recrystallize over time because the thermoplastic starch structure is not stable enough to limit the mobility of the starch molecules, migration and evaporation of the plasticizer over time. In contrast, NuPlastiQ does not undergo any significant degree of retrogradation or recrystallization. While some starch-based polymer materials are enzymatically debranched (e.g., increasing the amylose fraction, decreasing the amylopectin fraction), thereby reducing their molecular weight, the presently described starch-based polymer materials are generally not enzymatically treated for debranching or for other purposes, although they can exhibit reduced (or increased) molecular weight, and / or increased amylose content as compared to the starting starch material. In any case, the resulting molecular weight of the starch-based polymer material can be relatively high, as described herein.

[0225] In addition to the starch-based material being thermoplastic, the high molecular weight NuPlastiQ material can also be solid at ambient temperature, but flow as a liquid upon the application of heat, pressure, and / or friction. Advantageously, when blended with a diluent thermoplastic polymer as described herein, the pellets of high molecular weight NuPlastiQ can be used in standard plastic production processes, including fine fiber spinning processes (spunbond, meltblown, or yarn processes), approximately the same as any typical plastic resin pellets to achieve the desired rheological properties for such spinning.

[0226] The starch-based polymeric material itself can also be strain hardening without the need to add a strain hardening component to achieve such an effect. This apparent strain hardening characteristic of the NuPlastiQ starch-based material of the present invention is in contrast to the characteristics of other starch-based polymeric materials that appear to exhibit strain thinning characteristics that have worsened attempts to spin them. For example, even under constant applied shear conditions, the viscosity (flow resistance) of a strain hardening material will actually increase over time, whereas a strain thinning material behaves oppositely (the viscosity decreases over time). The starch-based material of the present invention can exhibit such strain hardening on its own without the need to add a separate strain hardening aid to the formulation. This strain hardening characteristic is important and valuable.

[0227] The starch-based material of the present invention appears to exhibit strain hardening characteristics that greatly facilitate the ability to effectively spin such starch-based materials. This characteristic is one of those characteristics that appear to be important in allowing such spinning to proceed, even with such very high molecular weight starch-based materials.

[0228] The starch-based material can be non-toxic, prepared using all edible raw materials. The resulting high molecular weight starch-based material can be water resistant. Applicant has interestingly observed that while films containing starch-based material in a fraction (e.g., about 25 wt%) as described herein can have a relatively low (e.g., 34 dynes / cm or less) surface wettability, similar to the hydrophobicity of many typical polyolefins (e.g., polyethylene or polypropylene), by contrast, in fiber form, Applicant has surprisingly observed that NuPlastiQ / PP nonwoven fabrics formed as described herein can be significantly more hydrophilic, with greater wettability and absorbency than comparable standard polypropylene nonwoven fabrics and fibers. Such increased wettability can be advantageous for some applications (e.g., disposable hygiene products, such as diapers, feminine hygiene products, etc.).

[0229] For example, by comparison, typical polyethylene and polypropylene films generally have a surface wettability rating of about 29 dynes / cm - 32 dynes / cm. Blends of NuPlastiQ with such polyolefins in film form can exhibit similar wettability, having a wettability value (e.g., measured according to DIN 53394 / ISO 8296) of less than 40 dynes / cm, less than 38 dynes / cm, less than 36 dynes / cm, or less than 34 dynes / cm under the dynes test. As noted above, although Applicant can not fully understand the reason, fiber forms of such blends as described herein appear to be considerably more hydrophilic (e.g., surface wettability greater than 34 dynes / cm, greater than 36 dynes / cm, greater than 38 dynes / cm, or greater than 40 dynes / cm).

[0230] Similar to paper, NuPlastiQ does not typically biodegrade under typical storage conditions (even under relatively humid conditions) because the absence of anaerobic digesters, industrial composting, or other typical conditions of disposal environments that contain specific desired microorganisms. Of course, where such conditions exist, not only is NuPlastiQ biodegradable, but a significant portion of the otherwise non-biodegradable plastic material (e.g., polypropylene) blended therewith also surprisingly exhibits biodegradation. Extensive such evidence is described in Applicant’s other patent applications, which are incorporated by reference herein.

[0231] The starch-based material can be substantially amorphous. For example, raw starch powder typically has about 50% crystalline structure. Many thermoplastic starch materials similarly have a relatively high degree of crystallinity. By way of example, the starch-based material as used as described herein can have a degree of crystallinity of less than about 40%, less than about 35%, less than about 30%, less than about 25%, less than about 20%, less than about 15%, less than about 10%, less than 9%, less than about 8%, less than 7%, less than about 6%, less than about 5%, or less than about 3%. Any suitable testing mechanism for determining degree of crystallinity can be used, for example, including but not limited to FTIR analysis, X-ray diffraction methods, and symmetric reflection and transmission techniques. Various suitable testing methods will be apparent to those skilled in the art.

[0232] As described herein, blending the starch-based material with plastic materials (e.g., thermoplastic materials having a higher melt flow index, selected to dilute and further plasticize the starch-based material) not only can result in the starch-based material being rapidly biodegradable, but the non-biodegradable thermoplastic materials included in the blend also actually become significantly more rapidly biodegradable (even where the high melt flow index thermoplastic material alone is not otherwise significantly biodegradable). Of course, such results do not occur within previously reported blends. Such results have been documented at least when blended with NuPlastiQ. It is believed that the high intimate blending of the starch-based component with other plastic materials, among other factors, can allow such occurrences.

[0233] Without being bound by any particular theory, it is believed that the starch-based material (e.g., particularly in the case of NuPlastiQ) can enable the two to intimately blend together and allow the microbial degradation of the otherwise non-biodegradable plastic molecules in the blend as well as the highly intimate dispersion of the starch-based material to disrupt the moisture barrier properties of the polypropylene or other non-biodegradable plastic material in the manner in which the arrangement and linkage of the starch-based material is disrupted. The highly intimate dispersion of the very small particles or domains of the starch-based component can also be important in any such mechanism as the microbes quickly encounter another polymeric material as the starch particles or domains are dispersed very well. As a result of such dispersion, the microbes can continue to “munch” on the polymeric material after consuming a given starch-based particle until they encounter the next adjacent starch-based particle (which can be more easily digested).

[0234] Indeed, PiFM analysis of such blends indicates that the typical separation of starch domains“islands” and relatively pure polyolefin“sea” does not form, but rather starch material is present even within the polyolefin“sea” and polyolefin is present within the starch“islands” such that the separate relatively pure domains present in conventional starch / polyolefin blends do not form. Additional details with respect to such analysis are found in the prosecution history of Applicant’s Application No. 15 / 481,823 (now U.S. Patent No. 10,919,203), the prosecution history of which is incorporated herein by reference. In contrast to conventional starch or starch-based materials, the blend of NuPlastiQ with another thermoplastic resin material exhibits a substantially lack of pure“sea-island” character. This does not mean that the blend cannot exhibit some heterogeneous morphology characteristics, but rather starch material is present even within any polyolefin“sea” and polyolefin is present within the starch“islands” such that the separate relatively pure domains present in conventional starch / polyolefin blends do not form. Such morphologies are also believed to occur in other plastics (e.g., polyesters, polystyrene, etc.) when blended with NuPlastiQ starch-based polymeric materials. Theoretically, the long polymeric chains of polypropylene or other non-biodegradable plastic materials can be more readily broken down in an environment where bacteria and microorganisms are active when uniformly blended with the presently contemplated starch-based materials. Subsequently, microorganisms naturally occurring in disposal environments (e.g., in an anaerobic digester or industrial compost) can consume the broken down molecules such that they are converted back to naturally occurring base mineralization components such as CO2, CH4, and H2O. Even in the event that such articles can be disposed in an undesirable environment (e.g., a landfill), the NuPlastiQ present in the blend can be used to more quickly achieve biodegradation of the non-starch components. At least in the case of NuPlastiQ, and in the testing conducted to date in film form, NuPlastiQ does not appear to promote macrostructure fragmentation into small pieces, but rather the formed articles tend to biodegrade while appearing to remain substantially intact throughout much of such process. It is believed that this biodegradation effect is further enhanced and more consistently achieved when the starch-based components are tightly and uniformly dispersed in very small domain sizes, for example, as described in Applicant’s U.S. Application No. 16 / 925,747 (21132.30.1) and U.S. Application No. 16 / 925,705 (21132.27.1.1), each of which is incorporated herein by reference in its entirety.While some prior art references can describe a blend morphology in which the starch or thermoplastic starch phase is in a discontinuous (or continuous) phase and the polyolefin or other plastic phase is in the other phase (e.g., a continuous plastic phase with a discontinuous starch phase, or vice versa), NuPlastiQ blends can not be structured in such a manner, but rather include the starch-based polymeric material in any polyolefin or other plastic resin phase, and include the polyolefin or other plastic resin material in the starch-based polymeric material phase.

[0235] Biodegradable plastics are converted via microbial assimilation (e.g., enzymatic action by microbes on plastic molecules) into natural building block compounds such as carbon dioxide, methane, water, inorganic compounds, or biomass. Such processes are sometimes referred to as “mineralization.”

[0236] Plastics made from petrochemical feedstocks typically begin life in the form of monomers (e.g., individual small molecules that can chemically react with other small molecules). When monomers are joined together, they become polymers (“many parts”), and can be referred to as plastics. Prior to being joined together, many monomers are readily biodegradable, but after being joined together by polymerization, the molecules become so large and connected in such an arrangement and connection that microbial assimilation by microbes is impractical in most cases within any reasonable time frame for many materials (e.g., including polyethylene and polypropylene, in particular). However, the high molecular weight NuPlastiQ starch-based compositions described in the present invention can impart increased biodegradability to other non-plant-based polymers.

[0237] Polyolefins, such as polyethylene and polypropylene in rigid forms, have a high degree of crystallinity and are made by converting monomer molecules, whether petroleum-derived or small building block molecules derived from ethanol or other plant-derived sources, into long chain polymers. The bonds created as the monomers link to form long polymer chains are strong and difficult to break. Fine fibers and articles formed from such polymeric materials, such as polyethylene and polypropylene, are not biodegradable as defined herein and have significant strength. Of course, there are now available some polymers that can be consumed by microbial assimilation under certain conditions and can be made spinnable (e.g., PLA can be industrially compostable according to ASTM D-5338 or ASTM D-6400 and some PLA can be spun), but such materials are significantly more expensive than polyethylene or polypropylene. Even in the case where a given article is formed from a blend of conventional non-biodegradable plastic material with a conventional thermoplastic starch "TPS" material described as suitable for spinning (e.g., as described in various references to Kimberly-Clark and P&G), any non-biodegradable plastic component of such a formulation will not acquire significant biodegradability properties as a result of such blending. For example, only the starch portion or other recognized compostable resin component of the blend (e.g., PLA) is capable of microbial assimilation, where access to such components is not blocked or obstructed by a non-biodegradable matrix that can prevent access to portions having some such components (e.g., as can occur in the case where the blend has a morphology that includes a continuous non-biodegradable phase that encapsulates a biodegradable or compostable phase).

[0238] The one or more starch-based materials can be present in the material mixture in any desired fraction. By way of example, the starch-based material can be included in the material mixture in an amount of at least 0.5 wt.%, at least 1 wt.%, at least 2 wt.%, at least 3 wt.%, at least 4 wt.%, at least 5 wt.%, at least 10 wt.%, at least 15 wt.%, at least 20 wt.%, not greater than 99 wt.%, not greater than 95 wt.%, not greater than 90 wt.%, not greater than 80 wt.%, not greater than 70 wt.%, not greater than 60 wt.%, not greater than 50 wt.%, 2 wt.% to 60 wt.%, 5 wt.% to 40 wt.%, 10 wt.% to 40 wt.%, 20 wt.% to 35 wt.%, or 20 wt.% to 30 wt.%. If desired, more than one starch-based material and / or more than one thermoplastic material specifically selected for its melt flow index or other properties can be included in the blend. Examples of properties used to identify additives or other components included in the blend can include molecular weight distribution, isotacticity (e.g., isotactic polypropylene), long chain branching, copolymers incorporating polypropylene isomers, and the like.

[0239] In at least some of the following examples, the inclusion of at least two thermoplastic materials, each exhibiting a different melt flow index value. In one embodiment, the inclusion of at least some threshold amount of a high molecular weight starch-based material, but it is possible that the article can include another starch-based material that can have a lower weight average molecular weight (e.g., less than 3 million, less than 2 million, or less than 1 million) or have other properties that are different from the primary starch-based material. That is, in one embodiment, it can not be intentional to add a lower molecular weight starch-based material. Of course, it will be appreciated that starch-based materials exhibit a distribution of molecular weights, and even the high molecular weight starch-based material itself can include some fraction of lower molecular weight molecules.

[0240] The thermoplastic diluent material blended with the starch-based material can be present in the material mixture in an amount of at least 1 wt.%, at least 2 wt.%, at least 3 wt.%, at least 4 wt.%, at least 5 wt.%, at least 10 wt.%, at least 15 wt.%, at least 20 wt.%, at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, at least 40 wt.%, at least 45 wt.%, at least 50 wt.%, no more than 99 wt.%, no more than 95 wt.%, no more than 90 wt.%, no more than 85 wt.%, no more than 80 wt.%, no more than 75 wt.%, more typically 10 wt.% to 90 wt.%, 20 wt.% to 85 wt.%, 40 wt.% to 80 wt.%, or 60 wt.% to 80 wt.%. More than one such thermoplastic material can be included in the blend (i.e., a combination of such thermoplastics, each having different melt flow index properties).

[0241] By way of example (e.g., for use in a spunbond process), the blend can include a significant portion of at least one thermoplastic material selected for a melt flow index of 50 to 600, 50 to 150, 75 to 125 (e.g., 100), or 400 to 600 (e.g., 500). For example, such a thermoplastic material can be present in the formulation in an amount of at least 5%, at least 10%, at least 20%, at least 30%, at least 40% (such as 40-60%) of the formulation along with a second additional thermoplastic material having a significantly lower melt flow index (e.g., 10 to 50, such as 35). Such a second thermoplastic material can be present in an amount of at least 5 wt.%, at least 10 wt.%, or at least 15 wt.% (such as 10 wt.% to 30 wt.% or 15 wt.% to 25 wt.%). Examples describe such a blend, for example, including 50% polypropylene having an MFI of 100 or 500, 21% polypropylene having an MFI of 35, 4% maleic anhydride modified polypropylene compatibilizer, and 25% high molecular weight starch-based polymer. Some examples include a total of 60 wt.% - 80 wt.% of two different diluent high melt flow index thermoplastic polymers (e.g., PP) in total.

[0242] Blends formulated for melt blown processing can have similar portions of thermoplastic materials selected for their melt flow indices, but the melt flow index values selected can be relatively higher for melt blown as the processing associated with the melt blown process is more demanding. For example, one of the thermoplastic materials used in the melt blown process can have a melt flow index of at least 500, 1000 to 2000 (e.g., 1500 to 1600) g / 10 min (e.g., at 230°C under 2.16 kg, particularly for polypropylene).

[0243] Blends formulated for yarn processing can have similar portions of thermoplastic materials selected for their melt flow indices, but the melt flow index values selected can be relatively lower for yarn as the processing and strength requirements associated with the yarn process are less demanding. For example, one of the thermoplastic materials used in the yarn process can have a melt flow index of 50 to 200 (e.g., 50 to 150, 75 to 125, such as about 100 g / 10 min at 230°C under a load of 2.16 kg). The same masterbatch material (e.g., including a 35 MFI diluent thermoplastic material) can be used for spunbond, melt blown, or yarn, with the primary difference being the MFI of the diluent thermoplastic material blended with the masterbatch material. In any case, it will be apparent that the general principle is to provide a resulting formulation with a low enough BPI shear viscosity (as described below) to run through a given fiber spinning system (spunbond, melt blown, or yarn) while avoiding melt flow instabilities within those portions of the process that exhibit the highest shear (e.g., at the spinneret). While it can be advantageous to use the same masterbatch formulation, e.g., the ability to use a single masterbatch for any of such processes, it will be appreciated that any of a variety of masterbatches can be provided, e.g., where the starch-based polymeric material is blended with a diluent thermoplastic material of any desired MFI (e.g., 35 MFI, 100 MFI, or other) in the masterbatch.

[0244] A compatibilizer can optionally be present in the material mixture, and is typically provided as a component of the masterbatch, although it can alternatively be provided separately. The compatibilizer can be a modified polyolefin or other modified plastic, such as a maleic anhydride grafted polyolefin (e.g., maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted polybutylene, maleic anhydride grafted polyolefin copolymer, combinations of any of the foregoing, etc.). The compatibilizer can include an acrylate-based copolymer. For example, the compatibilizer can include an ethylene methyl acrylate copolymer, an ethylene butyl acrylate copolymer, or an ethylene ethyl acrylate copolymer. The compatibilizer can include a poly(vinyl acetate)-based compatibilizer. In one embodiment, the compatibilizer can be a grafted form of one of the thermoplastic diluent materials (e.g., maleic anhydride grafted polypropylene, where the plastic material is polypropylene) or a copolymer (e.g., a block copolymer) where one of the blocks has the same monomer as the thermoplastic material (e.g., a styrene copolymer, where the thermoplastic material is polystyrene or ABS). The selection of a particular compatibilizer is typically dependent on the properties of the thermoplastic diluent resin material included in the blend, and the compatibilizer (if present) can be selected to provide good compatibility results between the high molecular weight starch-based material and any particular thermoplastic diluent material used.

[0245] If present, the final blend can include at least 0.5 wt.%, at least 1 wt.%, at least 2 wt.%, at least 3 wt.%, at least 4 wt.%, at least 5 wt.%, no more than 50 wt.%, no more than 45 wt.%, no more than 40 wt.%, no more than 35 wt.%, no more than 30 wt.%, no more than 25 wt.%, no more than 20 wt.%, no more than 15 wt.%, no more than 10 wt.%, no more than 9 wt.%, no more than 8 wt.%, no more than 7 wt.%, no more than 6 wt.%, 0.5 wt.% to 12 wt.%, 2 wt.% to 7 wt.%, or 4 wt.% to 6 wt.% of the compatibilizer. In some embodiments, no such compatibilizer will be required. Relative to such amounts, the masterbatch can include double or another multiple, depending on the blending ratio of the masterbatch relative to the thermoplastic diluent material with which it is blended. For example, where the final blend can desirably include 4% compatibilizer, the masterbatch can include 8% compatibilizer, which will be blended down in a 1 : 1 ratio.

[0246] One or more additional "active" additives known to be useful in the plastics industry can be included in the material mixture in an amount of at least 0.5 wt.%, at least 1 wt.%, at least 1.5 wt.%, at least 2 wt.%, at least 2.5 wt.%, at least 3 wt.%, at least 4 wt.%, no more than 10 wt.%, no more than 9 wt.%, no more than 8 wt.%, no more than 7 wt.%, no more than 6 wt.%, no more than 5 wt.%, 0.2 wt.% to 12 wt.%, 1 wt.% to 10 wt.%, 0.5 wt.% to 4 wt.%, or 2 wt.% to 6 wt.%.

[0247] By way of example, the spunbond, meltblown, yarn, or other spinning process used to form the article can include heating the material mixture. It has been observed that the viscosity of the starch-based material of the present application is particularly sensitive to temperature. For example, even though high molecular weight starch-based materials exhibit viscosity characteristics that are about an order of magnitude higher than those required for conventionally spun starch materials, applicants have found that such viscosity can be reduced through a combination of actions, including but not limited to selecting appropriate process temperatures at which the extrusion and spinning should be performed.

[0248] In one implementation, the material mixture can be heated to a temperature that is above the melting point of the polypropylene or other diluent thermoplastic polymer of the blend. For example, many polypropylenes can melt at temperatures of about 160 °C or higher, while many polyethylenes can melt at temperatures of about 110 °C or higher. By way of example, the temperature can be at least 130 °C, at least 140 °C, at least 150 °C, at least 155 °C, at least 160 °C, at least 165 °C, at least 170 °C, at least 175 °C, at least 180 °C, at least 185 °C, not more than 250 °C, not more than 230 °C, not more than 225 °C, not more than 220 °C, not more than 210 °C, not more than 205 °C, not more than 200 °C, not more than 195 °C, 180 °C to 210 °C, 185 °C to 205 °C, or 185 °C to 200 °C (e.g., 190 °C or 195 °C). While typical polypropylene processes can heat to about 230 °C, this temperature can be too high for the present compositions, where it is desirable to minimize heat-induced degradation of the starch-based polymeric material. Thus, in at least some embodiments, the temperature of the spinning system can not exceed 210 °C, or even 200 °C. Such lower temperatures can be thought to make spinning more difficult, as viscosity decreases with temperature, but applicants have found that spinning is possible at such lower temperatures and is advantageous to minimize degradation of the starch-based polymeric material. As described herein, applicants have also found that such temperatures are sufficient to provide the desired viscosity and other rheological characteristics to enable fiber spinning.

[0249] Heating of such material can occur within a multi-stage extruder that heats the material mixture to a given temperature at each extruder stage, with successive stages being heated to a higher temperature than the previous stage, e.g., as will be apparent to one of skill in the art. In one embodiment, the temperature of the first stage of such an extruder for the blend (where heating begins) can be in the same range as the temperature of the starch-based material in the reactive extrusion process used to manufacture the starch-based material (e.g., NuPlastiQ).

[0250] As noted above, it can be important to ensure that the processing temperature at which fiber formation occurs is not so high as to exceed the degradation temperature of the starch-based polymeric material. As noted above, heating can be used to reduce the viscosity of the formulation, and the starch-based materials employed herein exhibit a sharp reduction in viscosity with increasing temperature, which greatly facilitates ensuring that spinning of fibers is possible at commercial line speeds and attendant high shear rates (e.g., typically on the order of 1000 s -1 and higher in the spinneret) without the composition entering into melt flow instability.

[0251] For example, shear stress is equal to the melt (shear) viscosity times the shear rate, and it is important to keep the applied shear stress below the critical shear stress of the formulation in order to be able to spin fibers, e.g., at typical commercial spinneret shear rates of 1000 s -1 or higher. Typical resins suitable for spinning (e.g., polypropylene) exhibit a critical shear stress value of about 100 kPa, above which severe problems occur, making it impossible to achieve useful fiber formation. Some resins exhibit more favorable critical shear stress values, possibly as high as 300 kPa, providing additional latitude in engineering the system to ensure that the critical shear stress is not exceeded. The starch-based polymeric materials currently employed appear to exhibit a critical shear stress value above the typical 100 kPa limit, and can be as high as 300-400 kPa, providing additional latitude in engineering the system, which can allow for higher line speeds while still keeping the system below the applicable critical shear stress. Even when blended in a masterbatch with a diluent material having a relatively lower critical shear stress, the masterbatch comprising the starch-based polymeric material can still have a critical shear stress greater than 100 kPa, greater than 125 kPa, such as about 200 kPa. Such materials are very useful additives for increasing the critical shear stress of formulations processed under high shear conditions.

[0252] In any case, the mixture of materials comprising the thermoplastic diluent material and the starch-based material can be heated in one or more chambers of an extruder. In some cases, one or more chambers of the extruder can be heated at different temperatures. The speed of one or more screws of the extruder can be at any desired rate. In one embodiment, the system can be configured as a single screw extruder.

[0253] The material mixture is spun into fine fibers, for example, by a spunbond, meltblown, or yarn process. Depending on the process and desired end use, the formed fibers can be produced and wound to be used as an intermediate material in the manufacture of any of a variety of products. Also depending on the process and desired end use, the process can convert the formed fine fibers into a nonwoven web of such fibers, which can be bonded together, for example, by thermal calendering or other processes to produce a nonwoven. There are many other possible bonding mechanisms that can be used, which will be apparent to those skilled in the art (including, but not limited to, needlepunching, hydroentangling, through-air bonding, chemical adhesive bonding, etc.). Such processes can be used to bond the fibers of individual plies or layers together, or can also be used to bond individual plies or layers together, for example, when forming multi-ply or multi-layer composite structures that can incorporate different nonwoven materials in different layers or films. The processes described below can be used to form the nonwoven materials. Figures 21-23 Exemplary spunbond, meltblown, and yarn processes are schematically illustrated.

[0254] When forming nonwovens, the nonwoven web can include a single layer or multiple layers. The weight (e.g., basis weight) of such nonwoven layers or webs can be in any desired range. Exemplary weights are typically in the range of 10 g / m 2 (gsm) to 800 gsm, 10 g / m 2 (gsm) to 500 gsm, 10 g / m 2 (gsm) to 300 gsm, 10 g / m 2 (gsm) to 150 gsm, or 10 gsm to 100 gsm. Light weight nonwovens can be particularly useful, for example, 10 gsm to 20 gsm.

[0255] The articles described herein can exhibit significant biodegradation when subjected to biodegradation testing (e.g., according to any applicable ASTM standard, such as ASTM D-5511, ASTM D-5526, ASTM D-5338, or ASTM D-6691). Under such testing, and over a given period of time (e.g., 180 days, 365 days (1 year), 2 years, 3 years, 4 years, or 5 years), the articles can show substantial biodegradation of the total polymer content (including polymer components that are generally not biodegradable). Because the thermoplastic material also biodegrades, the articles made from the compositions of the present invention can show biodegradation greater than the content of the high molecular weight starch-based polymer material. Such results are novel because all prior art blends containing non-biodegradable plastic materials (e.g., polypropylene) and starch-based materials known to Applicant have exhibited biodegradation values that never exceed (and often are lower than) the content of the starch-based material of the blended material. For example, materials containing polypropylene such as those described in the Kimberley-Clark or P&G patent literature do not exhibit biodegradation of their polypropylene portion. The same is of course true where such literature describes starch blends containing other polymers that are considered non-biodegradable. Of course, some such references describe the use of recognized biodegradable or compostable polymers (e.g., PLA) to improve the biodegradation capability of the articles. The present invention solves the biodegradation capability in a completely different manner, rendering polypropylene and similar “inert” polymers susceptible to microbial assimilation. Of course, the incorporation or other use of PLA, PBAT, or other more “green” polymers in the blend (e.g., as the thermoplastic material having a particular selected melt flow index value) is also within the scope of the present invention. Biodegradation of polypropylene such as that contained in the current blend has been confirmed by various third party testing using industry-recognized biodegradation tests based on respirometry (e.g., ASTM D-5338, ASTM D-5526, ASTM D-5511, ASTM D-6991).

[0256] In particular, when the articles are subjected to simulated biodegradation testing under anaerobic digestion or industrial composting conditions for 180 days, 365 days (1 year), 2 years, 3 years, or 5 years, the biodegradation can be greater than the weight percent of the starch-based material within the article, and where no other recognized biodegradable material is contained. In other words, the inclusion of the described starch-based material can result in at least some biodegradation of other thermoplastic materials that alone can not significantly biodegrade in the absence of the starch-based material.

[0257] Articles made from the compositions of the present application having an amount of a starch-based material and another thermoplastic material as described herein can exhibit excellent biodegradation when subjected to biodegradation testing. For example, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or even at least 95% of the non-starch-based material (e.g., the “other” plastic material, such as polypropylene, another polyolefin, or other plastic that is not itself biodegradable) can biodegrade over a period of at least about 1 year, at least about 2 years, at least about 3 years, or at least about 5 years when tested according to any of ASTM D-5338, ASTM D-5526, ASTM D-5511, ASTM D-6991. Such biodegradation is particularly notable and advantageous.

[0258] The amount of biodegradation can be very high over time, such that in at least some implementations, substantially the entire article biodegrades, e.g., at least about 85%, at least about 90%, at least about 95% biodegradation, or at least equal to the biodegradation of a positive control (e.g., cellulose) under a given testing standard. Such results can be achieved within 180 days or 365 days (1 year), within 2 years, within 3 years, within 5 years, or within other time periods. Biodegradation can be considered substantially complete if the amount of biodegradation in the article is at least 90% of the amount achieved in a cellulose positive control tested under the same conditions for the same time period.

[0259] Figure 21 An exemplary spunbond process 100 is schematically illustrated. Those skilled in the art will recognize that the various components of the system can vary, and the illustrated system and process 100 are merely exemplary. As illustrated, the polymer blend can be fed into an extruder 104 through one or more hoppers 102. As described herein, the various components of the formulation (e.g., the starch-based polymeric material and the thermoplastic diluent plasticizing polymer (e.g., polypropylene having a desired MFI value)) can be provided in a single hopper, provided through different hoppers, etc. As described herein, the starch-based polymeric material can be provided as a masterbatch (e.g., available from the Applicant), in which the starch-based polymeric material has been pre-blended with at least one thermoplastic diluent material and optional compatibilizer. Such masterbatch can be further blended in the extruder 104 with additional thermoplastic diluent polymer.

[0260] A uniform blended formulation for spunbonding can be passed through filter 106 to remove any undesirable contaminants. A pump is provided at 108 that delivers the heated formulation (e.g., 195 °C) to a spinneret 110 in which fibers are formed due to the specific provided rheological properties of the formulation as described herein. A quenching portion of the system is shown at 112. At 114, the fibers are attenuated for deposition onto a substrate (e.g., a conveyor belt) 116 to form a desired nonwoven from the spun fibers from the spinneret, quenching, and attenuation portions of the system. The forming section associated with the substrate 116 can include one or more guide rolls 118 and edge guides 120 to facilitate the formation of a nonwoven web from the spun fibers. After formation, the nonwoven web can be passed through a compactor roll 122 and a calender roll 124 before the formed spunbond nonwoven web is wound onto a winder 126.

[0261] As described above and in the examples, the formulations used in a spunbond process such as process 100 include a starch-based polymeric material (e.g., in any weight portion as described herein, such as 1 wt% to 30 wt%, 5 wt% to 30 wt%, 2 wt% to 5 wt%, 5 wt% to 10 wt%, 10 wt% to 20 wt%, or 20 wt% to 30 wt% of the formulation blend). The thermoplastic diluent material is specifically selected to ensure that the shear viscosity of the resulting formulation is low enough to be able to run through the system 100, and in particular through the high shear spinneret fiber forming portion of the process, without melt flow instability. As described above and in the examples, the thermoplastic diluent can include polypropylenes having different MFI values, such as an MFI value of 35, an MFI value of 100, and an MFI value of 500. In one embodiment, a masterbatch can include 50% of the starch-based polymeric material, 8% of a compatibilizer, and 42% of a 35 MFI polypropylene, while additional polypropylenes (e.g., 100 MFI and 500 MFI) are added separately and blended with the masterbatch in the extruder 104. Such examples are merely exemplary, showing one possible formulation suitable for use in such spunbond systems and processes. By way of further example, a formulation can have a BPI (as described below) of less than 300 Pa-s and can be processed at 195 °C through a 0.35 mm die diameter at 2000 m / min to produce fibers having a diameter of about 20 pm. The tenacity of such fibers can be at least 1.4 gpd. Multi-structured fibers (e.g., sheath / core type or other geometries as described herein) are of course also possible.

[0262] Figure 22An exemplary melt blown process 200 is schematically illustrated. Those skilled in the art will recognize that the various components of the system can vary, and the illustrated system and process 200 is merely exemplary. As illustrated, a polymer blend can be fed into an extruder 204 through one or more hoppers 202. As described herein, the various components of the formulation (e.g., starch-based polymeric material and a thermoplastic diluent plasticizing polymer (e.g., polypropylene having a desired MFI value)) can be provided in a single hopper, provided through different hoppers, etc. As described herein, the starch-based polymeric material can be provided as a masterbatch (e.g., available from the applicant), where the starch-based polymeric material has been pre-blended with at least one thermoplastic diluent material and optionally a compatibilizer. Such masterbatch can be further blended in the extruder 204 with additional thermoplastic diluent polymer.

[0263] The uniform blend formulation for producing melt blown fibers can pass through a gear pump 206, which delivers the heated formulation (e.g., 205 °C) to a die body 210, where fibers are formed due to the specific provided rheological properties of the formulation as described herein. At 208, heated air (e.g., hotter than the polymer formulation, e.g., at 220 °C to 250 °C, such as 230 °C) is used to force the polymer melt through the dies of the die body 210, forming fine fibers that can pass through cooling air (not labeled), and where the fibers are collected on a collector 212, and can be wound on a winder 214.

[0264] As described herein, such melt blown processes form fibers that are generally smaller than those formed in spunbond processes (e.g., 2 pm - 4 pm versus 15 pm - 30 pm), and the formulation is subjected to more extreme conditions, thus generally requiring a thermoplastic diluent material having a higher melt flow index value for use in such melt blown processes. The melt blown fibers can be incorporated directly into nonwoven structures, often with spunbond layers (SMS), hybrid structures, etc., or wound as a separate layer.

[0265] As described above and in the examples, formulations used in melt-blowing processes, such as process 200, include a starch-based polymeric material (e.g., in any weight portion as described herein, such as 1 wt% to 30 wt%, 5 wt% to 30 wt%, 2 wt% to 5 wt%, 5 wt% to 10 wt%, 10 wt% to 20 wt%, or 20 wt% to 30 wt% of the formulation blend). The thermoplastic diluent material is specifically selected to ensure that the resulting formulation is low enough in shear viscosity to be able to run through system 200, and particularly through the die portion of the process, without melt flow instabilities, and be drawn into fine fibers by the hot air. As described above and in the examples, the thermoplastic diluent can include polypropylenes having different MFI values, such as a MFI value of 35 and a MFI value of 1550. In one embodiment, a masterbatch can include 50% of the starch-based polymeric material, 8% of a compatibilizer, and 42% of the 35 MFI polypropylene, while additional polypropylene (e.g., 1550 MFI) is added separately and blended with the masterbatch in the extruder 204 (e.g., at a 1 : 1 or other desired ratio). Such examples are merely exemplary, showing one possible formulation suitable for use in such melt-blowing systems and processes. By way of further example, a formulation can have a BPI (as described below) of less than 200 Pa-s, and can be run through a 0.4 mm die diameter at 205 °C to produce fibers having a diameter of about 2 pm - 4 pm. Multi-structured fibers (such as sheath / core or other geometries as described herein) are of course also possible.

[0266] Figure 23 An exemplary yarn process 300 is schematically illustrated. Those skilled in the art will recognize that the various components of the system can vary, and the illustrated system and process 300 are merely exemplary. As in other processes, a polymer blend can be fed into the extruder 302 through one or more hoppers. As described herein, the various components of the formulation (e.g., the starch-based polymeric material and the thermoplastic diluent plasticizing polymer (e.g., polypropylene having a desired MFI value)) can be provided in a single hopper, provided through different hoppers, etc. As described herein, the starch-based polymeric material can be provided as a masterbatch (e.g., available from the applicant), in which the starch-based polymeric material has been pre-blended with at least one thermoplastic diluent material and optionally a compatibilizer. Such masterbatch can be further blended with additional thermoplastic diluent polymer in the extruder 302.

[0267] A uniform blend formulation for yarn formation can be passed to pump 304, which passes the heated formulation (e.g., 205 °C) to a filter pack spinneret 306, where fibers are formed due to the specifically provided rheological properties of the formulation as described herein. Inlet air for the quench duct portion of the system is shown at 308. A spin duct is shown at 310, and a spin finish is shown at 312. The fibers exiting the spin duct 310 in such a yarn process (e.g., at 312) can be relatively thick, e.g., 60 pm, and can be formed at a relatively low line speed (e.g., 650 m / min). A godet roll is shown at 314, and a take-up roll is shown at 316. This initial portion of the process (left side portion of the process in Figure 23 results in the formation of relatively thick yarn fibers, where the formed fibers can be immediately stretched to a smaller diameter after initial fiber formation or later, as shown by the right side portion of the process in Figure 23 .

[0268] In any case, as shown in Figure 23 , the relatively thick yarn from the take-up roll 316 can be transferred to the draw stage of the yarn process, placed on a supply spool (also labeled 316, as it can simply be one of the filled take-up rolls). The relatively thick yarn is passed across draw rolls 320, and through a heater 318 (e.g., at 75 °C to 130 °C, such as 100 °C), where the yarn is drawn to a smaller diameter. By way of example, the draw ratio can be 2x to 5x or 2x to 4x (e.g., 2.8x). Depending on the material employed, there can be a heating tube (not shown) and a texturizing device 324. By way of example, in the case of using a polyamide material, there can be such a texturizing step. In the case of the thermoplastic diluent material employed being polypropylene or other similar material, no texturizing can be provided. At 326, the finished yarn is wound on a roll. By way of example, the finished yarn at 326 can have a diameter of about 20 pm, and be produced at a line speed of about 1800 m / min (as compared to the spun yarn that is later drawn at 60 pm and 650 m / min). By adjusting the speed differential and fiber temperature, the fiber bundle can be relaxed between the draw godet and the winder.

[0269] As described above and in the examples, formulations used in yarn processes, such as process 300, include a starch-based polymeric material (e.g., in any weight portion as described herein, such as 1 wt% to 30 wt%, 5 wt% to 30 wt%, 2 wt% to 5 wt%, 5 wt% to 10 wt%, 10 wt% to 20 wt%, or 20 wt% to 30 wt% of the formulation blend). The thermoplastic diluent material is specifically selected to ensure that the resulting formulation is low enough in shear viscosity to be able to run through system 300, and particularly through the spinneret fiber forming portion of the process, without melt flow instability. As described above and in the examples, the thermoplastic diluent can include polypropylenes having different MFI values, such as 35 MFI value and 100 MFI value. In one embodiment, the masterbatch can include 50% starch-based polymeric material, 8% compatibilizer, and 42% 35 MFI polypropylene, while additional polypropylene (e.g., 100 MFI and / or a blend of 100 MFI and additional 35 MFI PP) is added separately and blended with the masterbatch in extruder 302. Such examples are merely exemplary, showing one possible formulation suitable for use in such yarn systems and processes. By way of further example, a formulation can have a BPI (as described below) of less than 600 Pa-s or less than 500 Pa-s, and can be processed at 650 m / min in the spinning portion of the process and 1800 m / min in the drawing portion of the process through a 0.35 mm die diameter at 205°C to produce fibers having a diameter of about 20 pm. The tenacity of such fibers can be at least 2.5 gpd. Multi-structured fibers (such as sheath / core or other geometries as described herein) are of course also possible.

[0270] IV. EXAMPLES

[0271] Example 1

[0272] Exemplary formulations having various component ranges are shown in Table 2 below, along with some exemplary rheological properties for meltblown, spunbond, and yarn.

[0273] Table 2

[0274]

[0275] A variety of starch-based polymeric materials were rheologically evaluated for the present application, and a particular starch-based polymeric material was selected for spinning based on the measured properties. The base starch or majority of the starch in the evaluated materials was corn starch (Cornl or Corn2). Cornl is an unmodified starch from naturally yellow dent corn. Corn2 is a modified corn starch. In the formulations used in the spinning examples described herein, the starch-based polymeric material was formed from a single starch (Corn2) rather than a mixture of two different starches (Cornl or Corn2 + potato). The formed starch-based material exhibited very high weight average molecular weight, e.g., as described herein. In one embodiment, the molecular weight (e.g., number average and / or weight average molecular weight) of the starting starch material (e.g., corn starch) can actually be less than the molecular weight of the starch-based polymeric material resulting after reactive extrusion with a plasticizer, as determined by size exclusion chromatography. In other words, in some cases, the reactive extrusion process can actually result in an increase in average molecular weight, e.g., a decrease in polydispersity. By way of example, analysis of Corn2 (modified corn starch) showed the following molecular weight properties.

[0276] Table 3A

[0277] Run 1 Run 2 Mn 3,410,000 2,230,000 Mw 8,700,000 7,190,000 Mz 28,900,000 82,000,000

[0278] The polydispersity (Mw / Mn) for Run 1 and Run 2 for this modified corn starch material was 2.55 and 3.22, respectively. An exemplary starch-based polymeric material formed from the corn starch of Table 3A and a plasticizer (e.g., glycerol) included the following molecular weight properties as shown in Table 3B. The formed starch-based polymeric material had a polydispersity (Mw / Mn) of 1.99. The reported Mz value refers to the "third moment" molecular weight, which has more weight toward higher molecular weight.

[0279] Table 3B

[0280] Starch-based polymeric material Mn 5,370,000 Mw 10,700,000 Mz 33,400,000

[0281] In performing the rheological studies, it was determined that 190 °C was a good temperature for the studies, hot enough to melt the polypropylene and other components of the formulation, but low enough to comfortably manage the stability of the starch-based polymeric material (i.e., prevent degradation). Limited additional testing was performed at additional temperatures (e.g., 180 °C to 205 °C).

[0282] Cogswell elongational viscosity measurements were performed on three samples. Temperature sweep measurements were performed on two other samples. The viscosity versus shear rate for sample 984 is shown in Figure 1Sample 984 is shown in Table 1. Sample 984 is formed from Cornl as a base corn starch blended with some potato starch (e.g., 30%). The sample was dried at 60°C for 2 hours to remove any residual water. Two test runs of sample 984 were performed, and the test runs exhibited good reproducibility. As shown in Table 1, the sample exhibited a very high melt viscosity at 190°C of 4,000 Pa-s at 10 s Figure 1 and other figures (e.g., Figure 7A ), the high molecular weight starch-based polymeric material has a very high viscosity. As noted above, the starch-based polymeric material used in the spinning example was formed from Corn2 and exhibited a slightly lower viscosity, but the viscosity characteristics were still at least an order of magnitude higher than starch-based materials that have been suitable for fine fiber spinning in the past. Such a dramatic difference is due, at least in part, to the very high molecular weight of the starch-based material of the present invention. For example, referring to Figure 1 , at a shear rate of 10 s -1 , the high molecular starch-based material sample 984 exhibited a melt or shear viscosity of over 4,000 Pa-s (e.g., at 190°C). Although such a low shear viscosity is very high, the material exhibits excellent shear thinning characteristics, as at a shear rate of 200 s -1 , the shear viscosity has dropped to about 600-700 Pa-s, and at a shear rate of 1000 s -1 , the shear viscosity has dropped to about 200-300 Pa-s (again at 190°C). Although this is a significant drop in viscosity, it is still higher than the desired target of no more than 125 Pa-s, no more than 95 Pa-s, or no more than 50-65 Pa-s at 1000 s -1 at 190°C.

[0283] By testing various formulations prepared, it was observed that the rheological behavior of the starch-based materials was dominated primarily by the base corn starch, with Cornl having a much higher viscosity than Corn2. That is, in both cases, the starch-based materials had a very high weight average molecular weight, e.g., over 5 million. In comparison to a 1 MI (melt index) LLDPE (see Figure 2 ), the starch-based polymeric materials prepared from both base corn starch materials exhibited roughly similar shear viscosities at low shear, but also exhibited higher shear sensitivity. It was also observed that the flow curves were smooth and substantially parallel at high shear rates (with a possible 3-5x difference in the coefficients between the two), but also exhibited a non-linear "up-tail" characteristic at shear rates below about 100 s -1 . Such a dramatic non-linear up-tail (where the shear viscosity increases even more sharply than the existing exponential increase associated with a linear relationship on a log scale) is unusual and can be unique to the high molecular weight starch-based materials of the present invention. Figures 1-2 ​

[0284] Figure 2 Flow curves are shown for both a starch-based material formed from Cornl corn starch and a starch-based material formed from Corn2 corn starch, along with a comparative curve for 1MI PE (1MI LLDPE). As seen in Figure 2 the shear viscosity of the starch-based polymeric material formed from Corn2 is significantly lower than the shear viscosity of an otherwise similar material made from Cornl (e.g., about 2-4 times lower). As shown in Figure 2 for example, the shear viscosity of the material formed from Corn2 is 10 s -1 about 2,000 Pa-s to about 3,000 Pa-s, 200 s -1 about 300 Pa-s to about 400 Pa-s and 1000 s -1 about 100 Pa-s. As noted above, the shear viscosity of the material formed from Cornl is 10 s -1 about 6,000 Pa-s, 200 s -1 about 1000 Pa-s and 1000 s -1 about 400 Pa-s (all measurements taken at 190 °C).

[0285] Figure 3 Additional flow curves are shown for other exemplary starch-based materials formed from one or more starches and plasticizers in ratios as described herein. These curves include flow curves for various examples formed from a single starch or combinations of different starches. The flow curves show how the addition of potato starch to the starch blend forming the starch-based polymeric material decreases the resulting viscosity properties as the starch content increases. Also shown are curves for various examples where Corn2 is the base starch, showing different flow curves for including varying amounts and / or types of potato starch in the starch mixture forming the starch-based material. In Figure 3 In particular, sample 985 is formed from corn starch CI, sample 937 is formed from corn starch C2, and the other samples are formed from blends of corn and potato starches. The selection of the starch material used to form the starch-based material can greatly affect the resulting rheological properties.

[0286] Reference is made to Figure 4, higher viscosity samples allow for the melt flow instability characteristics of high molecular weight starch-based materials to be explored. Note the sharp break or inflection in the flow curve above 300 kPa, which is a typical plateau break (i.e., indicative of a melt flow instability and a critical shear stress threshold). Such very high critical shear stress values are also advantageous and help make it possible for the inventive compositions containing large fractions of starch-based polymeric materials to be spun at commercial line speeds. For example, by comparison, polypropylene, which is widely used for spinning fine fibers, has a critical shear stress of only about 100 kPa. This characteristic of the starch-based materials of the present invention allows for the occurrence of melt flow instabilities to be delayed or postponed because more of the starch-based material is contained in the formulation being spun. Such a characteristic also advantageously allows a portion (e.g., even a small portion) of the starch-based materials of the present invention to be added as an additive to conventional polypropylene or other spinning formulations that exhibit relatively lower critical shear stress values (e.g., about 100 kPa) to effectively increase the critical shear stress of such formulations. This would allow for faster line speeds, etc., which would be another particular advantage provided by the starch-based materials disclosed herein.

[0287] For example, one embodiment of the present invention can thus involve the use of such starch-based materials for increasing the critical shear stress of a given spinning formulation by adding a desired amount of such materials. The amount of starch-based material added can be in any desired range and need not be particularly high to postpone the occurrence of melt flow instabilities of the composition. By way of example, the amount of starch-based polymer added as a critical shear stress enhancer can be any of the values disclosed herein. In one embodiment, the addition can be relatively small, e.g., less than 20%, less than 15%, less than 10%, less than 5%, etc.

[0288] As shown, the flow curves of the starch-based materials formed are substantially parallel at shear rates above 100 s -1 -1. Since processing in a spunbond or other fiber spinning system (e.g., extruder, pipe, die manifold, etc.) typically involves the application of shear rates in the range of 10 to 500 s -1 -1, the shear viscosity at a shear rate of 200 s -1 -1 is a reasonable representation of the viscosity in such processing environments. Such conditions (e.g., 200 s -1At 190 °C, using a 1 mm die, L / D = 30) BiologiQ Processing Index (BPI) was calculated or measured based on the viscosity of such components used in the formulation to be used as a benchmark to evaluate various components and resulting formulations. BPI can be a good process control tool. Finally, since the flow curves of various starch-based materials are typically parallel to each other, this also provides information on the die pressure up to the critical shear stress (e.g., τ > 300 kPa). BPI (in poise or Pa-s) can be quickly calculated by linearly adding the contribution of the components included in the formulation.

[0289] Examples of thermoplastic elastomers can include, but are not limited to, random or block poly(propylene / ethylene) copolymers (e.g., consisting primarily of isotactic propylene repeat units with random ethylene distribution therein), SEBS, SBS, SIS, or another styrene (e.g., block) copolymer.

[0290] A flow curve was prepared for a formulation containing 50% of a high molecular weight starch-based material and 35 MFI PP. The high molecular weight starch-based material was formed from a 90 / 10 mixture of corn and potato starch (e.g., 90% Corn 2, 10% Potato 1). The formulation had the following components shown in Table 4 below.

[0291] Table 4

[0292] Component Amount BPI High MW starch-based material 50％ 293 PP (MFI 35) 37％ 240 Random PE-PP copolymer 5％ 396 Compatibilizer 8％ 31

[0293] The rheological properties of the blend were very similar to those calculated. For example, using the BPI values, it was calculated that the BPI was 259.

[0294] To evaluate the effect of temperature on the starch-based material, sample 877 (based on Corn 2) was run at 180 °C, 190 °C, and 200 °C. A sample formed from Corn 2 was also evaluated at 205 °C. Table 5 below shows the temperature data obtained for sample 877, another sample formed from Corn 2 (without potato starch), and 35 MFI PP.

[0295] Table 5

[0296]

[0297] Key materials were selected for blending with the prepared starch-based materials to produce formulations suitable for spunbond, meltblown, and yarn production of fine fibers. In one embodiment, the formulations can be prepared to obtain a 1000 s -1of no more than 125 or no more than 95 (e.g., no more than 50-65) Pa s at a shear rate of 200 s -1 of no more than 500 Pa s, 300 Pa s, 275 Pa s, 250 Pa s, 240 Pa s, 230 Pa s, 220 Pa s, 200 Pa s, 190 Pa s, 180 Pa s, 170 Pa s, 160 Pa s, 150 Pa s, 140 Pa s, or 130 Pa s at a shear rate of 200 s

[0298] Figure 5 A flow curve is shown for an exemplary starch-based polymeric material formed from Corn 2, along with a constant shear stress line of 100 kPa (at which instability of the PP typically occurs). Figure 5 A spinneret diameter is also shown (e.g., 0.35 mm to 0.6 mm), which can be as typically used for various spinning processes described herein. A typical flux rate of 1 g / min per hole is used to calculate the shear rate. As noted above, the PP is pushed to the limit of the current large number of commercial processes (i.e., high line speeds). Figure 6 Additional flow curves are shown, for example, for various additives (e.g., PPs having varying MFI values of 35 to 1600 g / 10 min).

[0299] A particularly suitable blend material for spunbond applications can include a combination of 100 MFI and 500 MFI PPs. Blends of 35 MFI and 500 MFI PPs can also be used as thermoplastic polymer diluent materials having particularly selected melt flow index properties. Table 6 below shows the shear viscosity of exemplary blend components at 190 °C at different shear rates (100, 1000, and 10,000 s -1 ) for a variety of different blend ratios.

[0300] Table 6

[0301] Component 100s -1 ]] 1000s -1 ]] 10,000s -1 ]] Corn2 NuPlastiQ 472 112 35 45 MFI PP-PE copolymer 313 117 23 22 MI PP homopolymer 350 104 21 2.5 MI PP homopolymer 533 122 26 35 MFI PP 350 93 17 500 MFI PP 44 30 11

[0302] Table 7 below shows estimated shear viscosity values (at 1000 s -1 below) for various compositions as blends of starch-based material and 35 MFI polypropylene (PP) (50 / 50, 35 / 65, 25 / 75).

[0303] Table 7

[0304]

[0305] As shown by the various flow curves, the starch-based material has very high viscosity at low shear rates (e.g., 100 s -1 , 10 s -1 or less) and very high viscosity at applicable strain rates. Formulations including 25% of the starch-based material in 35 MFI PP (e.g., a masterbatch) have manageable low shear viscosities, which can be further improved by compounding with high MFI PP (e.g., 100 to 2000 MFI PP). Formulations including 25% of the starch-based material, 50% of 500 MFI PP, 21% of 35 MFI PP, and 4% of maleic anhydride PP compatibilizer were successfully used to spin fine fibers having a fiber diameter of < 16 pm. This same formulation was used to co-extrude bi-component fibers with 100 MFI PP to a 10 / 90 sheath / core ratio. Images of such fine fibers formed are shown in the figures. Bi-component core / sheath fibers were also formed, with high molecular weight NuPlastiQ in the core and PP, PLA, or PE in the sheath. Different types of core / sheath fibers were formed, with up to 22% NuPlastiQ in the core. The fibers were drawn to less than 20 pm, which fiber size is suitable for use in spunbond nonwoven webs. Nonwoven fabrics were also produced from the homopolymer fibers, having a weight basis of 45 gsm - 50 gsm and 10 gsm - 15 gsm. Fabrics can also be produced from the co-extruded fibers.

[0306] Figures 7-7A Additional flow curve data for various prepared and tested formulations is shown. These figures show that the low shear viscosities of the starch-based polymeric materials described herein are higher, and they can be reduced by blending with the diluent plasticizers described herein. Figure 7A The specific target values shown in Table 8 are exemplary initial target points. As described herein, Applicant has successfully spun fibers with formulations having BPI values higher Figure 7A than the target values listed in Table 8.

[0307] Table 8 shows process characteristics for various formulations used to spin fine fibers.

[0308] Table 8

[0309]

[0310] 1, 2 and 3 represent first, second and third high molecular weight NuPlastiQ masterbatches. Each masterbatch comprises 50% HMW NuPlastiQ, 32-42% 35 MFI PP, 8% compatibilizer and 0-10% other additives (e.g. copolymer). Figures 8-9 Some such fibers that have been formed are shown.

[0311] Table 9 shows similar data to Table 8, but for spun sheath / core fibers.

[0312] Table 9

[0313]

[0314] Bicomponent fibers can have unusual physical and aesthetic properties that can make them high value products compared to standard fibers. This is often done to combine the properties of polymers, or to exploit differences in properties (e.g. melting point) (e.g. by putting a lower melting component in the sheath). Exemplary bicomponent fibers include sheath / core fibers, eccentric sheath / core fibers, side-by-side fibers, fan-pie fibers and island-in-the-sea fibers. Other types are of course possible. Figures 10-17 Some of such bicomponent fibers that have been formed are shown.

[0315] Reference Figures 10-17fibers, the ratio of sheath to core varies from 50 / 50 to 10 / 90. Those skilled in the art will appreciate that sheath / core ratios below 10 / 90 are also possible, such as 5 / 95, or even thinner sheaths. Such values refer to the fraction of material (mass fraction) for each geometric segment (e.g., 50 mass% sheath, 50 mass% core, or 10 mass% sheath and 90 mass% core). Assuming the densities of the different feeds are approximately equal, these values can also refer to the ratio of cross-sectional area of the different geometric portions (e.g., sheath vs. core). By way of example, in the case of a bicomponent sheath / core fiber having a diameter of about 15-20 μιη (e.g., 18 μιη), thus, for a 50 / 50 sheath / core ratio (sheath thickness = 2.5 μιη), the core can have a diameter of about 13 μιη. Thus, at a 10 / 90 sheath / core ratio, the core can have a diameter of about 17 μιη, while the sheath would have a thickness of 0.5 μιη. While calculations are made for an 18 μιη diameter fiber, it will be appreciated that other sizes are of course possible. More generally, the core diameter can thus be 70-90% of the fiber diameter, while the sheath thickness can be 1-15% of the fiber diameter. While the location of the starch-based material is in the core in the illustrated bicomponent fiber, the location can be switched (e.g., the starch-based material is in the sheath). It will be apparent that in such bicomponent fibers (whether sheath / core or other geometry), the size of the fiber portion comprising the high molecular starch-based material can be significantly smaller than the size of the entire fiber formed from the same composition. Surprisingly, the high molecular weight starch-based compositions of the present invention can be pushed or otherwise extruded through this small geometry.

[0316] Surprisingly and unexpectedly, the present applicant was able to spin fibers from compositions comprising a majority of high molecular weight starch-based material (e.g., having a weight average molecular weight as described herein). The examples of the present invention show the use of a higher MFI PP homopolymer to dilute the formulation to develop a formulation that reduced the viscosity properties, allowing the formation of spunbond filaments or fibers containing 25% of the starch-based material, down to 17 microns, which is a size suitable for a spunbond process. Additionally, the examples show the ability to co-extrude this formulation with PP, PLA, PBAT, and PE in a sheath / core configuration.

[0317] It was also observed that a formulation containing 25% starch-based material could be processed at 190°C at a very high shear rate of 6400 s -1 Without melt fracture occurring. This property is advantageous because it would not be possible for a conventional PP material to show melt flow instability at such a high shear rate.

[0318] Figure 18Flow curves for an exemplary formulation comprising 25% high molecular weight starch-based material, 50% 500 MFI PP, 21% 35 MFI PP, and 4% compatibilizer at 190°C are shown, including low shear data obtained using a cone and plate rheometer. BPI data for such a formulation is shown in Table 10.

[0319] Table 10

[0320] Target (Pa-s) Actual (Pa-s) BPI (η) (at 200 s -1 down) ≤300 108 (η) (at 1000 s -1 down) ≤125 52

[0321] Table 11 shows the effect of including a 500 MFI diluent component on η0.

[0322] Table 11

[0323] Composition [η0 (Pa-s)] 100% HMW NuPlastiQ >10 7 ]]> 25% HMW NuPlastiQ, 71% 35 MFI PP, 4% compatibilizer 1500 25% HMW NuPlastiQ, 50% 500 MFI PP, 21% 35 MFI PP, 4% compatibilizer 275

[0324] While the examples show fine fiber spinning with high molecular starch-based polymer material, with the addition of a high melt flow index thermoplastic diluent material to reduce shear viscosity so as to enable processing of such formulations at 190°C - 195°C, formulations comprising higher concentrations of starch-based components can also be processed at commercial line speeds (i.e., without slowing down the production line, which is prohibitively expensive and should be avoided) by increasing the processing temperature or adjusting various other parameters (e.g., formulation additives). For example, at 190°C and below, the shear viscosity is too high for 100% high molecular weight starch-based material, resulting in excessive pressure. In addition, the elongational viscosity is too high. Elongational viscosity is opposite to fine filament stretching, and results in filament breakage just below the spinneret. Formulations comprising 100% (or close to 100%, e.g., 80% - 100%) high molecular weight starch-based polymer material can be processed at higher temperatures, e.g., 220°C or higher, so long as material degradation can be avoided.

[0325] Example 2

[0326] Example 2 shows additional spunbond fiber production. Figure 19A spinning envelope is shown for 100 MFI PP and 35 MFI PP, both run at 225 °C. The plot also shows 100 MFI PP at 195 °C. Using these data and additional knowledge gained, a tenacity target of 1.75 grams per denier (gpd) was set. It was observed that 100 MFI PP had nearly the same rheology as a composition according to the invention formed from 25% starch-based polymeric material, 21% 35 MFI PP, and 50% 500 MFI PP. Thus, the 100 MFI curve can be used as a target or template for the desired parameters of a composition according to the invention that will include a starch-based polymeric material. The data indicated that the tenacity of nonwovens prepared in the early tests was less than 0.8 gpd. To measure tenacity, the filaments were collected just below the aspirator. Figure 19 The data shown in Table 1 indicates that for fibers of size 18-20 pm, a spinning speed of 2500 MPM or higher will be desirable. This can be achieved with a flow through the system of 0.7 g / min / hole or higher.

[0327] The extrusion section of the test line was used to extrude into a feed roll to measure tenacity. The feed roll provides a well-defined spinning speed as opposed to an aspirator which depends on inter-filament friction. The samples were run on a homo pack at 195 °C and 0.7 g / min / hole, and on a bico pack at slightly higher g / min / hole values. It was observed that the starch-containing formulations can be run up to about 2000 MPM, while 100 MFI PP can be run up to 2500 MPM. A 50 / 50 dry blend of sample CP1199 (a starch-based polymeric material masterbatch as described herein) with 500 MFI PP and a 50 / 50 twin-compounded blend of sample CP1199 with 500 MFI PP (labeled sample 1421 in Table 2) gave a tenacity of about 1.1 gpd, which is consistent with the spinning envelope shown in Figures 19-20 Figure 19 Sample 1451 performed the best with a tenacity of 1.4 gpd. This formulation is different from sample 1421 in that some of the 500 MFI PP is replaced with 100 MFI PP in this composition. Specifically, sample 1451 includes 50% CP1199 starch-based material masterbatch, 20% 100 MFI PP, and 30% 500 MFI PP. The main factor that helped improve the tenacity was reducing the amount of low molecular weight PP, i.e., 500 MFI PP. Of course, higher spinning speeds also increased the tenacity as shown in Figure 19

[0328] ​​The specific properties of the selected polypropylene can also affect tenacity. For example, the thermoplastic polymer mixed with the starch-based polymeric material can be specifically selected because it is able to reduce the strain rate in spinning (e.g., resulting in a more tapered draw profile). By way of example, the inclusion of such a thermoplastic polymer in a 10% concentration blend can increase tenacity by 15%. For example, the inclusion of Vistamaxx can increase tenacity to some extent (but at the cost of additional cost and higher BPI). Sample 1451 has exhibited higher BPI than sample 1421. Additionally, the zero shear viscosity of either of these two samples should be greater than the target value, as low shear viscosity is important for drawing the fiber under the spinneret.

[0329] Rheological data for the samples measuring tenacity is summarized in Table 12 below.

[0330] Table 12

[0331]

[0332] A copolymer was added to the blend in the extruder. As described above, samples 1451 and 1450 nominally included similar components. Sample 1450 included a polypropylene copolymer having isotactic structure and atactic structure (e.g., MFI less than about 1000 or less than about 100 g / 10 min measured at 230 °C under a load of 2.16 kg) to reduce the strain rate in spinning (e.g., resulting in a more tapered draw profile, as opposed to the typical neck draw of polypropylene) as compared to the polypropylene used in sample 1451.

[0333] Figure 20 Rheotens plots are shown for various samples. The Rheotens data indicates that sample 1451 is superior to the other samples, although there is apparent variability in the test data. Each sample was run 3 times, and the best sample in each sample was used for comparison.

[0334] In addition to the benefits provided by the increased sustainability provided by replacing some of the conventional thermoplastic resin materials of a spinnable formulation with the high molecular weight starch-based polymers of the present invention, other benefits are provided by such adjustments to the formulation. For example, the extrusion rate can be improved by extending the onset of melt flow instability at higher shear rates (increased output). Additionally, rheological data indicates a favorable high critical shear stress associated with such high molecular weight starch-based materials, which can provide an increase beyond the typical onset of melt flow instability. During the experiments conducted, the applicants were able to spin at 190 °C at a higher than 6400 s -1Extrusion at shear rates without observable instability. Polypropylene has been reported to exhibit melt flow instability at 100 kPa. For example, if a starch-based polymer material itself can exhibit a critical shear stress of 300 kPa or higher, then even if it is included in the spun formulation at a content of 25%, the critical shear stress can increase from about 100 kPa in a single polypropylene composition to a possible 150 kPa in a blend containing a starch-based polymer material. This would allow processing at increased shear rates, higher linear velocities, etc., without melt flow instability.

[0335] The strength of the nonwoven web formed from the fine fibers described herein can be increased, for example, by adjusting the composition, the post-extrusion bonding method employed (e.g., details of calendering or other bonding methods), or by adjusting other parameters. Strength can also be increased by improved compounding (e.g., utilizing high molecular weight starch-based materials), by adding additives configured to increase elongation (e.g., additives obtained under the trade name Vistamaxx, which consist primarily of isotactic propylene repeating units having a random ethylene distribution, or other additives), by increasing the processing temperature while reducing the highest MFI component (which may be something “weakly bonded”), by blending high molecular weight starch with lower molecular weight starch (so as to reduce the concentration of high melt flow index thermoplastic components), or a combination thereof.

[0336] Embodiments of the present invention can promote the biodegradation of polypropylene or other non-biodegradable components in formulations, enhance the biodegradability of other materials (e.g., polyester), increase softness, increase wettability and / or absorbency compared to polypropylene alone, allow the use of renewable starch-based components to replace a portion of fossil fuel resins (e.g., polypropylene), and / or reduce costs.

[0337] The uniformity of filament diameter is excellent, even at 16 μm. In some fibers, as shown in the figure, protrusions are observed on the outer surface or within the formed fiber. These protrusions typically exhibit a diameter variation of 1 μm–4 μm. In at least some embodiments, such protrusions may be desirable and advantageous. Where protrusions are not desired, they can be covered (e.g., by applying a sheath in a bicomponent fiber) or by adjusting various parameters described herein.

[0338] Example 3

[0339] Example 3 illustrates melt blown fiber production. The same or similar masterbatch as used in the spunbond examples was used to produce melt blown fibers. The masterbatch included 50% NuPlastiQ, 42% 35 MFI polypropylene, and 8% compatibilizer. The masterbatch was blended with 1550 MFI polypropylene in various ratios up to 50:50 (10 / 90, 20 / 80, 30 / 70, 40 / 60, and 50 / 50) and used to produce melt blown fibers, the results of which are shown in Table 13. For the melt blown testing, 2 masterbatches were tested.

[0340] Table 13

[0341] Blend % NuPlastiQ Diameter (pm) Average Pressure (psi) BPI 1550 MFI PP 0 2.64 61 11 10 / 90 5 4.13 52 34 20 / 80 10 2.21 67 58 30 / 70 15 3.01 82 82 40 / 60 20 3.94 122 105 50 / 50 25 2.84 150 129 50 / 50 25 2.39 187 180

[0342] The last 50 / 50 sample was prepared using the second masterbatch sample, while the first 50 / 50 sample and those samples including 5%-25% NuPlastiQ were prepared using the first masterbatch sample. The melt blown line included a 31 hole spin pack with 0.4 mm diameter die holes and was run at 205°C polymer melt temperature, 230°C air under 0.19 g / min / hole. Fabrics were made from the melt blown fibers, with fabric weights of about 18 gsm ± 4 gsm. As shown in Table 13, the fiber diameters were 2-4 μιη. The values in gms / hole can more typically range from 0.05 to 1 g / min / hole or 0.13 g / min / hole to 0.5 g / min / hole. The polymer melt temperature can more typically be less than 225°C, although higher than 230°C is typical for polypropylene. The BPI values for the 2 NuPlastiQ samples were 248 and 350 Pa-s, respectively, both of which were suitable for melt blowing after appropriate dilution. The machine direction (MD) tensile strength was measured at 1.1 kg for the pure polypropylene sample (1550 MFI PP in Table 13) and the sample including 20% NuPlastiQ (40 / 60 in Table 13). The elongation of these samples was measured to be 13.2% and 31.5%, respectively.

[0343] Example 4

[0344] Example 4 illustrates yarn production. The same 1631 masterbatch as used in the meltblown example was used to produce yarn fibers. The masterbatch comprised 50% NuPlastiQ, 42% 35 MFI polypropylene, and 8% compatibilizer. The masterbatch was blended with additional 35 MFI polypropylene and 100 MFI polypropylene to provide a blend comprising 50% masterbatch and 25% of either the added 35 MFI polypropylene or 100 MFI polypropylene. The formulation comprised 25% starch-based polymeric material (NuPlastiQ). The system was run at a melt temperature of 205 °C with a 72-hole spin pack and a 0.35 mm die hole diameter. The spin speed in the spinning portion of the yarn process was 638 m / min, producing spun yarn fibers having a diameter of about 60 pm. For the draw portion of the process, the draw temperature was 100 °C, the draw ratio was 2.8x, and the take-up speed was 1750 m / min. The produced fiber was 2.5 denier per filament (dpf), tenacity was 2.49 gpd, and elongation was 70.38%. Such yarn fibers can be used as precursors to produce air-laid or wet-laid bases for weaving, knitting, etc., carded nonwovens, cut or crimped fibers.

[0345] In addition to producing yarns using the above blend, similar yarns can be produced from the following formulations: (1) a formulation prepared by blending 50% of the masterbatch with 50% of the 100 MFI polypropylene; or (2) a formulation prepared by blending 50% of the masterbatch with 50% of the 35 MFI polypropylene.

[0346] Features from any of the disclosed embodiments or claims can be combined with each other without limitation, except where combinations are not functionally possible. It should be understood that the scope of the disclosure extends to rewording any claim to depend from any other claim, to include multiple dependent claims from any combination of other claims, and / or to combine multiple claims together. This also extends to any individual feature or combination of features from any of the embodiments as described in the SUMMARY and DETAILED DESCRIPTION sections. The scope of the disclosure extends to inserting and / or removing any feature or combination of features from any claim or described embodiment to insert another claim or embodiment, or to draft a new claim from any other claim or embodiment that includes any combination of these features.

[0347] It will be further understood that various changes in the details of the application can be made without departing from the spirit or scope of the application. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the application is indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning of the equivalency of the claims are intended to be embraced therein.

Claims

1. A method for spinning a composition comprising a starch-based polymeric material to produce a spunbond nonwoven, a meltblown fine fiber, or a yarn fiber made therefrom, the method comprising: providing a composition comprising a starch-based polymeric material, wherein the starch-based polymeric material has a crystallinity of less than 20% and resists recrystallization; and performing at least one of (a), (b), or (c): (a) melt spinning the composition to produce a fiber comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity greater than 50 Pa-s and not more than 300 Pa-s at a process shear rate of 200 s -1 at 190 °C, and avoids melt flow instability during the melt spinning process; or (b) melt extruding the composition to produce a film comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity greater than 50 Pa-s and not more than 300 Pa-s at a process shear rate of 200 s -1 at 190 °C, and avoids melt flow instability during the melt extrusion process. (b) melt blowing the composition to produce fibers comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity greater than 50 Pa-s and not more than 200 Pa-s at a process shear rate of 200 s -1 and avoids melt flow instability during the melt blowing process at 190 °C. or (c) spinning the composition to produce a yarn fiber having a spun diameter of 40 µm to 150 µm, the yarn fiber comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity of greater than 50 Pa-s and no more than 600 Pa-s at 190 °C at a process shear rate of 200 s -1 and avoids melt flow instabilities during spinning of the yarn fiber; and drawing the spun yarn fiber from its spun diameter to a smaller diameter.

2. The method of claim 1, wherein, The method includes performing (a), and the composition exhibits a shear viscosity greater than 50 Pa-s and no more than 300 Pa-s at a process shear rate of 200 s -1 The method includes performing (a), and the composition exhibits a shear viscosity greater than 50 Pa-s and no more than 300 Pa-s at a process shear rate of 200 s -1 The method includes performing (a), and the composition exhibits a shear viscosity greater than 50 Pa-s and no more than 300 Pa-s at a process shear rate of 200 s 3. The method of claim 1, wherein, the method comprises performing (a), and wherein the starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol.

4. The method of claim 1, wherein, the method comprises performing (a), and wherein the composition is a blend of the starch-based polymeric material and at least one thermoplastic polymer.

5. The method of claim 4, wherein, the at least one thermoplastic polymer comprises a polymer having a melt flow index of greater than 100 g / 10 min, 200 g / 10 min to 1000 g / 10 min, or 400 g / 10 min to 600 g / 10 min as measured at 230°C under a load of 2.16 kg.

6. The method of claim 4, wherein, the at least one thermoplastic polymer comprises at least two grades of polypropylene, a first grade having a melt flow index of 400 g / 10 min to 600 g / 10 min as measured at 230°C under a load of 2.16 kg, a second grade having a melt flow index of less than 100 g / 10 min as measured at 230°C under a load of 2.16 kg, and an optional third grade having a melt flow index of 75 g / 10 min to 125 g / 10 min as measured at 230°C under a load of 2.16 kg.

7. The method of claim 6, wherein, the at least one thermoplastic polymer further comprises an additional grade of polypropylene having both isotactic structure and atactic structure, the polypropylene having a melt flow index of less than 1000 g / 10 min as measured at 230°C under a load of 2.16 kg.

8. The method of claim 4, wherein, the at least one thermoplastic polymer comprises a thermoplastic polymer that is biodegradable on its own under industrial composting conditions.

9. The method of claim 8, wherein, the thermoplastic polymer that is biodegradable on its own under industrial composting conditions is a polyester.

10. The method of claim 1, wherein, the method comprises performing (a), and wherein the starch-based polymeric material has a water content of no more than 2% including any bound water.

11. The method of claim 1, wherein, the method comprises performing (a), and wherein the method produces fibers having a diameter of 10 µm to 50 µm.

12. The method of claim 1, wherein, the method comprises performing (a), and wherein the starch-based polymeric material is included in the composition in an amount of up to 60 wt%, up to 40 wt%, or in an amount of 1 wt% to 35 wt%.

13. The method of claim 1, wherein, the method comprises performing (a), and wherein the starch-based polymeric material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

14. The method of claim 1, wherein, the method comprises performing (b), such that the method comprises a method for meltblowing a composition comprising a starch-based polymeric material to produce fine fibers therefrom, the method comprising: A composition comprising a starch-based polymeric material is provided, wherein the starch-based polymeric material has a crystallinity of less than 20% and is resistant to recrystallization; and melt blowing the composition to produce fibers comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity greater than 50 Pa-s and not more than 200 Pa-s at a process shear rate of 200 s -1 and avoids melt flow instability during the melt blowing process at 190°C.

15. The method of claim 14, wherein, The composition exhibits a shear viscosity greater than 50 Pa-s and not more than 200 Pa-s at a process shear rate of 200 s -1 at 190°C, and a shear viscosity not more than 85 Pa-s at a spinneret shear rate of 1000 s -1 at 190°C.

16. The method of claim 14, wherein, The starch-based polymeric material is a high molecular weight starch-based polymeric material having a weight average molecular weight of at least 3 million g / mol.

17. The method of claim 14, wherein, The composition is a blend of the starch-based polymeric material and at least one thermoplastic polymer.

18. The method of claim 17, wherein, The at least one thermoplastic polymer comprises a polymer having a melt flow index as measured at 230°C under a load of 2.16 kg of greater than 500 g / 10 min, or 1000 g / 10 min to 2000 g / 10 min.

19. The method of claim 17, wherein, The at least one thermoplastic polymer comprises at least two grades of polypropylene, a first grade having a melt flow index as measured at 230°C under a load of 2.16 kg of 1000 g / 10 min to 2000 g / 10 min, and a second grade having a melt flow index as measured at 230°C under a load of 2.16 kg of no more than 100 g / 10 min.

20. The method of claim 19, wherein, The at least one thermoplastic polymer further comprises an additional grade of polypropylene having both isotactic structure and atactic structure, the polypropylene having a melt flow index as measured at 230°C under a load of 2.16 kg of less than 1000 g / 10 min.

21. The method of claim 14, wherein, The starch-based polymeric material has a water content including any bound water of no more than 2%.

22. The method of claim 14, wherein, The method produces fibers having a diameter of 2 µm to 10 µm.

23. The method of claim 14, wherein, The starch-based polymeric material is included in the composition in an amount of up to 60 wt%, up to 40 wt%, or 1 wt% to 35 wt%.

24. The method of claim 14, wherein, The starch-based polymeric material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

25. The method of claim 1, wherein, The method includes performing (c) such that the method comprises a method for producing a yarn fiber from a composition comprising a starch-based polymeric material, the method comprising: providing a composition comprising a starch-based polymeric material, wherein the starch-based polymeric material has a crystallinity of less than 20% and is resistant to recrystallization; spinning the composition to produce a yarn fiber having a spun diameter of 40 µm to 150 µm, the yarn fiber comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity of greater than 50 Pa-s and no more than 600 Pa-s at 190 °C at a process shear rate of 200 s -1 and avoids melt flow instability during spinning the yarn fiber; and stretching the spun yarn fiber from its spun diameter to a smaller diameter.

26. The method of claim 25, wherein, The diameter after stretching the yarn fiber is 10 µm to 50 µm.

27. The method of claim 25, wherein, The starch-based polymeric material is a high molecular weight starch-based polymeric material having an average molecular weight of at least 3 million g / mol.

28. The method of claim 25, wherein, The composition is a blend of the starch-based polymeric material and at least one thermoplastic polymer.

29. The method of claim 28, wherein, The at least one thermoplastic polymer comprises a polymer having a melt flow index as measured at 230°C under a load of 2.16 kg of 10 g / 10 min to 100 g / 10 min.

30. The method of claim 28, wherein, The starch-based polymeric material is provided in the form of a masterbatch, pre-blended with a first thermoplastic polymer, the method further comprising blending the masterbatch with a second thermoplastic polymer, wherein the first thermoplastic polymer and the second thermoplastic polymer have different melt flow index values.

31. The method of claim 28, wherein, The at least one thermoplastic polymer further comprises an additional grade of polypropylene having both isotactic structure and atactic structure, the polypropylene having a melt flow index of less than 1000 g / 10 min as measured at 230°C under a load of 2.16 kg.

32. The method of claim 25, wherein, The starch-based polymeric material has a water content, including any bound water, of no more than 2%.

33. The method of claim 25, wherein, The starch-based polymeric material is included in the composition in an amount of up to 60 wt% or up to 40 wt%.

34. The method of claim 33, wherein, The starch-based polymeric material is included in a masterbatch in an amount of up to 60 wt% and the starch-based polymeric material is included in the composition being spun in an amount of up to 40 wt%.

35. The method of claim 25, wherein, The starch-based polymeric material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

36. The method of claim 1, wherein, The method includes performing (a) such that the method includes a method for spinning a composition comprising a starch-based polymeric material to produce a spunbond nonwoven therefrom, the method comprising: providing a composition comprising a starch-based polymeric material, wherein the starch-based polymeric material has a crystallinity of less than 20% and is resistant to recrystallization; and providing a composition comprising a starch-based polymeric material, wherein the starch-based polymeric material has a crystallinity of less than 20% and is resistant to recrystallization; and melt spinning the composition to produce fibers comprising the starch-based polymeric material, wherein the composition exhibits a shear viscosity greater than 50 Pa-s and not more than 300 Pa-s at 190°C at a process shear rate of 200 s -1 and avoids melt flow instabilities during the melt spinning process.

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