Nonwoven materials and fibers comprising starch-based polymeric materials

Abstract

Very high molecular weight (e.g., greater than 2 million, such as 3 million to 20 million g / mol) starch-based materials and blends containing such starch-based materials that can be spun into spunbond, meltblown, yarn, or similar processes have been described. Even at such very high molecular weights, the blends can be spun for up to 1000 seconds without the onset of melt flow instability. -1 The starch-based material can be processed at commercial line speeds with a spinneret shear viscosity of 100 kJ / cm. The starch-based material can be blended with one or more thermoplastic materials having higher melt flow index values, which act as diluents and plasticizers, allowing the highly viscous starch-based component to be spun under such conditions. The particular melt flow index characteristics of the thermoplastic diluent material can be selected based on the type of process being used (e.g., spunbond, meltblown, yarn, etc.). The starch-based material can exhibit high shear sensitivity, strain hardening behavior, and / or very high critical shear stresses (e.g., at least 125 kPa).

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Patent Application No. 63 / 033,676 (21132.31), filed June 2, 2020, U.S. Patent Application No. 17 / 327,536 (21132.31.1), filed May 21, 2021, U.S. Patent Application No. 17 / 327,577 (21132.31.2), filed May 21, 2021, and U.S. Patent Application No. 17 / 327,590 (21132.31.3), filed May 21, 2021, each of which is incorporated by reference in its entirety herein.

[0002] This application also incorporates by reference U.S. Patent Application No. 16 / 925,747 (21132.30.1), filed July 10, 2020; U.S. Patent Application No. 16 / 925,952 (21132.28.1.1), filed July 10, 2020; U.S. Patent Application No. 16 / 925,705 (21132.27.1.1), filed May 29, 2019; U.S. Patent Application No. 16 / 425,397 (21132.20.1), filed April 23, 2019; U.S. Patent Application No. 16 / 391,909 (21132.14.1), filed August 30, 2017; U.S. Patent Application No. 15 / 691,588 (21132.7), filed September 14, 2015; U.S. Patent Application No. 14 / 853,725 (21132.8), filed June 30, 2015. U.S. Provisional Patent Application No. 62 / 187,231 filed on September 14, 2015 (21132.6), U.S. Patent Application No. 14 / 853,780 filed on September 14, 2015 (21132.1), U.S. Patent Application No. 15 / 481,806 filed on April 7, 2017 (21132.2), and U.S. Provisional Patent Application No. 62 / 440,399 filed on December 29, 2016 (21132.3). No. 1132.10), U.S. Provisional Patent Application No. 62 / 442,432 (21132.11), filed January 4, 2017, U.S. Provisional Patent Application No. 16 / 456,303 (21132.9.1), filed June 28, 2019 (now U.S. Patent No. 10,752,759), and U.S. Provisional Patent Application No. 15 / 836,555 (21132.4.1), filed December 8, 2017. [Background technology]

[0003] Conventional petrochemical-based plastics are formulated to be strong, lightweight, and durable. For this reason, they are used in large quantities in countless consumer products. However, these plastics are generally not sourced from sustainable materials and are typically not biodegradable to any significant extent, resulting in hundreds of millions of tons of plastic remaining in landfills or other natural environments (oceans, other waterways, soil, etc.). To reduce the amount of plastic waste, some items typically made using petrochemical-based plastics are being made using more rapidly biodegradable materials and / or from components sourced in part from renewable resources.

[0004] Many such plastic materials are manufactured in the form of nonwoven fibrous substrates or other articles containing thin fibers. While some progress has been made in incorporating renewable ingredients into some monolithic plastic articles and even plastic film materials, there has been little success in incorporating such renewable ingredients into nonwoven materials, nor into articles formed from thin fibers. This lack of progress is particularly applicable to the incorporation of starch-based polymeric materials into such articles. This is due in no small part to the typical high molecular weight and complex branching characteristics of typical starch materials, which typically contain significant amounts of branched amylopectin. The high molecular weight and associated high viscosity characteristics make the incorporation of such materials into nonwovens and other thin fibers challenging, and rheological properties must be carefully controlled to effectively form fibers for spunbond, meltblown, yarn, carded, airlaid, and similar processes using the desired thermoplastic formulation.

[0005] As noted above, most petrochemical-based plastic materials (including those used in the production of nonwoven fabrics) are typically not readily biodegradable. Examples of such materials include, but are not limited to, polyethylene, polypropylene, polyethylene terephthalate, polyester, polystyrene, ABS, polyvinyl chloride, polycarbonate, nylon, and the like. This non-biodegradable characteristic is true even in the case of so-called "green" versions of such materials (e.g., Green PE made by Braskem), which may typically be sourced from renewable sources rather than petrochemical feedstocks. Such "green" versions of plastics have few, if any, physical property differences from their fossil-fuel-derived cousins, e.g., their C 14 Against C 12 Even when it is possible to source some components of a plastic material from renewable sources, the inclusion of starch-based polymeric materials tends to result in materials that cannot be manufactured into nonwoven fabrics, for example, via typical spunbond, meltblowing, yarn production, and similar processes, due to the poor rheological properties of the resulting material due to the inclusion of starch-based components in such formulations.

[0006] The literature describes several attempts to incorporate starch or starch derivatives into blends of petrochemicals or other plastic materials used to form nonwoven fabrics, but such attempts have met with little commercial success due to the problems identified above, increased costs, the need to slow down manufacturing lines to accommodate such formulations, poor physical properties of the blends, etc. For example, U.S. Patent Nos. 6,818,295, 6,946,506, 7,666,261, U.S. Patent Application Publication Nos. 2002 / 0168518, 2002 / 0188041, 2003 / 0077444, 2010 / 0159777, 2019 / 0330770, and EP 326517(A1) may describe various attempts to produce nonwoven articles comprising starch-based polymeric materials, but the applicant is not aware of any currently commercially available products that provide such, for example, due to the problems discussed above.

[0007] For example, P&G's U.S. Patent No. 7,666,261 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 to improve melt flow and melt processability. The composition is typically predominantly starch with a small amount (e.g., <10%) of added high-molecular-weight polymer. The starch must be modified, for example, by reducing its molecular weight to a value of 2 million or less. The starch composition retains about 5-8% bound water even after formation of fibers or other articles. This reference relates to the formation of small fibers (e.g., 5 μm or less).

[0008] P&G's U.S. Patent No. 6,946,506 also describes a starch composition containing starch and a biodegradable polymer. Non-biodegradable polymers may also be present (e.g., up to 40%). The composition typically contains a high fraction of starch (e.g., typically 40-60%) with a similar fraction of biodegradable polymer (e.g., crystallizable PLA is specifically described). The starch composition retains approximately 5-16% bound water. Small fibers are reportedly capable of forming (e.g., 10-50 μm). To be suitable for use, the starch must be modified to have a molecular weight of 2 million or less.

[0009] P&G's U.S. Patent No. 6,818,295 also describes a starch composition containing starch, a thermoplastic polymer (e.g., PE, PP, PCL), and a plasticizer. For example, an acid-substituted vinyl polymer, such as ethylene acrylic acid (Dow Primacor), can be added. It is stated that it is possible to produce highly attenuated fibers containing microfibrils formed from a starch matrix. Similar to the '506 patent, the composition typically contains a high fraction of starch (e.g., 40-60%) with a similar fraction of thermoplastic polymer. The starch composition retains approximately 5-16% bound water. Small fibers are reportedly capable of forming (e.g., 5-30 μm). It is stated that the starch must be modified to have a molecular weight of 8 million or less, typically 2 million or less. While molecular weight values ​​up to 8 million are mentioned, there is no evidence of successful use of such. For example, each of the examples uses StarDri 100, StaDex 10, or StaDex 65 starch products from Staley; although the actual molecular weights of such products are not mentioned in the patent, they are believed to be less than about 1 million, as StarDri 100 was measured by applicant to have a weight average molecular weight of only about 21,000 daltons.

[0010] P&G's U.S. Patent Application No. 2003 / 0077444 recognizes that fiber formation is more difficult than other methods of forming articles (e.g., injection molding, blown film, etc.) because the time period during which the structure forms is very short and proper fiber formation requires very specific rheological and other properties. Starch is particularly problematic because, even if it can be formed into fibers, it has low tensile strength, is sticky, and does not bond well when attempting to form nonwoven webs. Blending starch with thermoplastic polymers can be useful, 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, pie-segmented, etc.). While native starch can have a MW of up to 60 million and a broad molecular weight distribution, starch needs to be modified to have a MW of 2 million or less to function adequately. Starch is typically present at 40-60%, but it can be higher or lower. Too high a molecular weight for a particular component can 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%, but it can also be higher or lower. Spunbond nonwoven web structures can be formed from such fibers. Fiber diameters are typically reported to be 5-30 μm. At least 15% polymer is required to achieve thermal adhesion.

[0011] P&G's U.S. Patent Application No. 2002 / 0188041 contains a similar disclosure to U.S. Patent Application No. 2003 / 0077444, and is more specifically directed to fibers comprising starch, a plasticizer, and a biodegradable thermoplastic polymer.

[0012] Kimberly-Clark, U.S. Patent Application No. 2010 / 0159777, describes a thermoplastic starch that has been enzymatically debranched (reduced amylopectin) to increase the amylose fraction to 55-60%. The composition further includes a plasticizer. It is heated at 160°C for 1000 seconds. -1 It has an apparent melt viscosity of 1 to 100 Pa at 2500 rpm. The molecular weight of the debranched starch is said to be up to 5 million, more typically 800,000 to 2 million, or significantly less than 2 million, as shown in Figure 5 after enzymatic debranching.

[0013] Kimberly-Clark's U.S. Patent Application No. 2019 / 0330770 also describes spun fibers formed from blends of 70-90% polyolefin (e.g., PP or PE) and 10-30% starch for use in wet-laid nonwoven manufacturing processes. While the starch is said to have a weight-average molecular weight of 5-25 million, there are no examples demonstrating success at such high molecular weights. As with other references, the actual example used reported a molecular weight of 2.9 million, suggesting that the molecular weight must be reduced to be suitable for use. This patent identifies the problems of previous (2000-2010) references (such as those discussed above) in that the blends were not actually suitable for running at commercial line speeds due to fiber crumbling.

[0014] EP 326517 A1 simply describes a method for disrupting starch.

[0015] It would be advantageous in the art to provide fibers, nonwoven articles, and methods for the production of each, which may include very high molecular weight starch-based polymeric materials (e.g., significantly higher molecular weights than any of those successfully demonstrated in the references discussed above). It would be further advantageous if the inclusion of such starch-based polymeric materials enhanced, or at least did not significantly impair, the mechanical properties of such fibers, nonwovens, and the like, compared to the base resin material used alone. It would be a further advantage if such compositions could be processed into fibers and nonwoven webs on conventional equipment at commercial line speeds, whether using spunbond, meltblowing, yarn production processes, or other similar processes involving the production of thin fibers from polymer blends. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] U.S. Patent No. 6,818,295 [Patent Document 2] U.S. Patent No. 6,946,506 [Patent Document 3] U.S. Patent No. 7,666,261 [Patent Document 4] US Patent Application Publication No. 2002 / 0168518 [Patent Document 5] US Patent Application Publication No. 2002 / 0188041 [Patent Document 6] US Patent Application Publication No. 2003 / 0077444 [Patent Document 7] US Patent Application Publication No. 2010 / 0159777 [Patent Document 8] US Patent Application Publication No. 2019 / 0330770 [Patent Document 9] European Patent Application Publication No. 326517 Summary of the Invention

[0017] Applicant's co-pending applications, as incorporated by reference above, disclose starch-based polymeric materials (e.g., thermoplastic starch materials) that can be blended with various plastic resin materials while substantially maintaining the desired strength and other physical properties of the materials with which they are blended. Such starch-based materials, available under the trade name NuPlastiQ, are believed to achieve strong intermolecular bonds between the starch-based material and the plastic resins with which they are blended. Such strong bonds contrast with those achieved in many prior art attempts to blend such plastic resins with starch or starch-based materials, in which the starch or starch-based material merely functions as a filler, typically reducing strength and adversely affecting other physical properties.

[0018] Applicants have now discovered that at least some grades of these starch-based polymeric materials having very high molecular weights can be formed into thin fibers, such as those useful for forming nonwoven web substrates (e.g., but not limited to, for use in diapers, sanitary napkins, disposable drapes, hospital gowns, surgical and other masks, pads, wipes, and the like). Such thin fibers can be produced by spunbond, meltblowing, yarn production processes, or other similar extrusion spinning processes that produce thin fiber structures from polymer melts or blends. As used herein, "spinning" refers to such processes (spunbond, meltblowing, yarn spinning, or similar extrusion processes used to spin thin fibers). While some techniques incorporate starch to some degree into fibers to make nonwoven webs, it has been important to carefully control the molecular weight of the starch component included in such compositions for the compositions to be processable under the necessary spinning conditions. For example, the above references demonstrate the formation of fibers in which the properties of the starch component are tightly controlled (e.g., molecular weights of 2 million or less), and the starch component typically exhibits other properties (e.g., moisture content, including 5-16% bound water) that differ from those of the present embodiment. While it has been reported that native starches can contain molecular weights much higher than 2 million, the art known to the applicant has not successfully demonstrated the ability to actually spin compositions containing such very high molecular weight starch materials and from which fabrics (e.g., nonwoven fabrics) or other fibrous products can be made. This is because, particularly considering that viscosity increases with increasing molecular weight, those skilled in the art (including at least some of the present inventors) have believed that starch components with very high molecular weights, e.g., 5-10 million or more, cannot be spun. For example, if a starch-based polymer is included in the formulation to any significant extent and at such very high molecular weights, it is predicted that the rheological properties required to be able to spin such compositions cannot be achieved.

[0019] According to one embodiment, the present invention provides 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 a starch-based polymeric material and, for example, by spinning the starch-based polymeric material at shear rates typical of commercial spinning production lines (e.g., about 1000 s -1 with a spinneret shear rate of more than about 200 s -1 The present invention is directed to a method for spinning a composition by spinning the composition at a suitable temperature (e.g., in the range of 170°C to 230°C, up to 205°C, or up to 195°C) at a process shear rate of about 1000 s or less. Under such conditions, according to certain formulations described herein, the composition may have a spinneret shear viscosity (e.g., 1000 s or less) of about 125 Pa·s or less, 120 Pa·s or less, 115 Pa·s or less, 110 Pa·s or less, 105 Pa·s or less, 100 Pa·s or less, 95 Pa·s or less, 90 Pa·s or less, 85 Pa·s or less, 80 Pa·s or less, 75 Pa·s or less, 70 Pa·s or less, 65 Pa·s or less, 60 Pa·s or less, 55 Pa·s or less, 50 Pa·s or less, 45 Pa·s or less, 40 Pa·s or less, 35 Pa·s or less, 30 Pa·s or less, 25 Pa·s or less, 20 Pa·s or less. -1 and 190°C). Similarly, the composition may exhibit a process shear viscosity (e.g., at 200 s or less) of about 600 Pa·s or less, 500 Pa·s or less, 400 Pa·s or less, 300 Pa·s or less, 275 Pa·s or less, 250 Pa·s or less, 240 Pa·s or less, 230 Pa·s or less, 220 Pa·s or less, 210 Pa·s or less, 200 Pa·s or less, 190 Pa·s or less, 180 Pa·s or less, 170 Pa·s or less, 160 Pa·s or less, 150 Pa·s or less, 140 Pa·s or less, 130 Pa·s or less. -1and 190°C). Such rheological properties are possible even while including a substantial fraction of starch-based polymeric materials having very high molecular weights, making the process effective for producing fibers including high molecular weight starch-based polymeric materials. Because the actual shear threshold may vary depending on the process used (e.g., spunbond vs. meltblown vs. yarn), more generally, the process and formulation may simply be configured to provide the formulation with a shear viscosity low enough to pass through the system at commercial line speeds and shear rates, and the formulation, whether spunbond, meltblown, yarn, or other, exhibits rheological properties that allow it to avoid the development of melt flow instabilities within the system (particularly the spinneret). The above values ​​include spinneret and process shear viscosities for each such process. As a more specific example, the shear viscosity for meltblown may be lower than the shear viscosity for yarn, which may be lower than the shear viscosity for spunbond. For example, the meltblown process shear viscosity can be less than 200 Pa·s, such as from 30 Pa·s to 180 Pa·s, or from 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 from 20 Pa·s to 70 Pa·s, or from 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 from 130 Pa·s to 215 Pa·s, or from 150 Pa·s to 200 Pa·s. The spunbond spinneret shear viscosity can be less than 95 Pa·s, such as from 50 Pa·s to 85 Pa·s, or from 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 from 100 Pa·s to 275 Pa·s, or from 150 Pa·s to 250 Pa·s. The yarn spinneret shear viscosity can be less than 120 Pa·s, such as from 50 Pa·s to 95 Pa·s, or from 75 Pa·s to 95 Pa·s.

[0020] As described herein and as can be understood by those skilled in the art, formulations containing starch-based polymeric materials can be formulated differently (e.g., using a diluent-plasticizer polymer, such as one added to a masterbatch formulation containing the starch-based polymeric material) to pass through a given specific process. For example, a formulation specifically tailored for a meltblown manufacturing process can have a shear viscosity characteristic that is lower than that of a spunbond process, and a spunbond formulation can have a shear viscosity characteristic that is lower than that of 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 method) while avoiding melt flow instabilities. As a broad example, a meltblown formulation can be formulated with a starch-based polymeric material, and the inclusion of a specific diluent plasticizes the polymer to achieve a process shear viscosity of less than 200 Pa·s (e.g., less than 200 s -1 Spunbond formulations can be compounded with starch-based polymeric materials, and the inclusion of certain diluents plasticizes the polymer to provide a process shear viscosity of less than 300 Pa·s (e.g., less than 200 s -1 The yarn production formulation may be compounded with a starch-based polymer material, and the inclusion of certain diluents plasticizes the polymer to provide a process shear viscosity of less than 600 Pa·s (e.g., less than 200 s -1 As noted above, in either case, the formulation may be formulated (through the 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 may also advantageously provide an extensional or elongational viscosity value (used interchangeably herein) that falls within a desired window to allow fiber formation. For example, if the extensional viscosity is too low, the fiber will break, but if the extensional viscosity is too high, the fiber will not be drawn as desired.

[0021] Under any of these fiber production process conditions, it is important that the blend remain below the onset of melt flow instability, ideally below 100 kPa for a polypropylene-dominated blend. As will be apparent to those skilled in the art, melt flow instability occurs when a critical shear stress (e.g., about 100 kPa for a typical polypropylene) is exceeded. Such critical shear stress values ​​are independent of temperature and depend on the blend's material properties (e.g., molecular structure, etc.). By way of example, exceeding such critical shear stress can result in gross surface irregularities associated with inlet and / or land fractures, resulting in undesirable or unusable manufactured products due to irregularities in the extrusion production surface. Other characteristics that may be associated with melt flow instability, which are also undesirable, include, but are not limited to, extensional resonance (causing pulsations in the extruded thickness) and secondary flow (causing interphase problems in multilayer extrusion products).

[0022] By way of example, in one embodiment, the starch-based polymeric material may have a weight average molecular weight of 3 to 20 million, or 5 to 16 million, although it will be apparent that lower molecular weight starch-based materials (e.g., molecular weights of 1 million or perhaps even lower) may also prove suitable for use, although lower molecular weight values ​​may also be suitable for use. By way of further example, exemplary starches from which the starch-based polymeric material is formed (e.g., formed from starch and plasticizer) may have a weight average molecular weight of at least 2 million, 3 million, 4 million, or 5 million, such as 3 to 10 million, or 5 to 7 million. The starch-based polymeric material may be formed from starches having a particular amylose content, e.g., 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. (eg, 130° C. to 250° C.) Extrusion of the starch and plasticizer can occur under pressure.

[0023] In one embodiment, the starch-based polymeric material is mixed with a thermoplastic polymeric diluent material, such as polypropylene, having a high melt flow index (e.g., at least 35, at least 50, at least 100, e.g., 35-2000, 35-1550, 35-1000, or 35-500), capable of further plasticizing the starch-based polymeric material. The melt flow index (MFI) of the selected diluent material can depend on the process to which the blend will be applied. For example, a meltblowing process may use a diluent with a relatively high MFI, a spunbond process may use a diluent with a medium MFI, and a yarn process may use a diluent with a relatively low MFI. Applicant has discovered that currently prepared starch-based polymer materials can have very high molecular weights (and therefore very high viscosity characteristics), which makes transport, shearing, and spinning very difficult. The particular starch-based polymer materials 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, so that shear rate can be used to dramatically improve flow characteristics, (iii) exhibit excellent response to diluents / plasticizers (the addition of small amounts of such polypropylene or similar thermoplastic polymers with a given melt flow index also dramatically affects flow characteristics), and (iv) exhibit relatively high critical shear stress characteristics (e.g., higher than polypropylene). In addition, the prepared starch-based polymer materials (v) exhibit excellent response to extrusion temperature (the material exhibits a significant decrease in viscosity as the extrusion temperature increases).

[0024] Such properties do not appear to be inherent in other starch-based polymer materials, and in fact, at least some such properties appear to be opposite to those of conventional starch-based polymer materials (e.g., the starch-based materials of the present invention appear to be strain hardening, whereas other TPSs are strain thinning). Strain hardening versus strain thinning should not be confused with shear thickening versus shear thinning. For example, shear thickening or shear thinning involves how a material behaves when shear is applied (e.g., whether it thickens or thins upon application of shear). In contrast, strain hardening versus strain thinning involves how a material behaves as a function of time under strain. If a material exhibits an extensional or extensional viscosity that increases over time during a drawing procedure, it is strain hardening. It can be inferred from the literature that typical starch materials, although naturally used for thickening, do not exhibit strain hardening behavior, in which the extensional or extensional viscosity increases when the material is drawn through a spinneret. Rather, existing starch materials appear too thin for this critical manufacturing stage, tending to stretch the material to points and cause it to break. Additionally, the particular starch from which the starch-based polymer NuPlastiQ material is formed can affect such properties (e.g., the selection of different grades of corn starch, cassava starch, potato starch, etc., used to make the high molecular weight starch-based material), as described in more detail below. In any case, suitable starch-based polymer materials for use in forming meltblown, spunbond, or yarn fibers described herein are available from the applicant under the NuPlastiQ trade name.

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

[0026] Another embodiment is directed to polymer blends suitable for use in forming thin fibers, such as those that can be used to form nonwoven webs through a spunbond process, in a meltblowing process, or in the production of yarns. 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 the overall desired rheological properties. The melt flow index (MFI) of the diluent material can depend on whether the blend is intended for use in a spunbond, meltblowing, or yarn process (or other process), with the diluent's MFI being specifically selected to ensure that (1) the resulting blend has a sufficiently low shear viscosity to be processed through such systems, (2) the resulting blend avoids melt flow instabilities when extruded through the spinneret of such systems, and (3) the blend provides an appropriate extensional viscosity to allow the fibers to be drawn without breaking. The two components (NuPlastiQ and a starch-based polymeric material, such as a thermoplastic diluent polymer) are typically intimately dispersed within one another. In one embodiment, the starch-based polymeric material may be present in an amount of up to 75%, up to 60%, up to 50%, or up to 40% by weight of the blend. The thermoplastic polymer may be present in an amount of up to 95%, or up to 90% by weight (e.g., more typically up to 75%) of the blend. Of course, in other embodiments, it may be possible to further increase the percentage of starch content, for example, by adjusting other manufacturing parameters as mentioned herein (e.g., increasing the process temperature, increasing the shear rate, etc., within the limits of degradation of the high molecular weight NuPlastiQ or other starch-based polymeric material).

[0027] Another embodiment is directed to thin fibers. For example, such thin fibers may be suitable for use in the manufacture of nonwoven webs (whether formed by a spunbond or meltblown process, for example). Thin fibers formed by a yarn process may be used, for example, to produce yarn products, or may be used, for example, to produce carded, airlaid, or wet-laid fibers. Such examples are merely illustrative, and such thin fibers produced by any of a variety of fiber spinning processes may be used in any of a wide variety of applications, as will be understood by those skilled in the art. Such fibers and nonwoven webs include a starch-based polymer material (e.g., NuPlastiQ) described herein (e.g., present in an amount of up to 60%) and a thermoplastic polymer material having a melt flow index configured to plasticize the starch-based polymer material so that it has the necessary rheological properties to pass through any spinning process to be employed. The components may be intimately dispersed together throughout the fiber. Of course, various non-uniform fiber geometries (eg, sheath / core, side-by-side, segmented pie, islands-in-the-sea, splittable fiber, or other) may also be achieved if desired.

[0028] Another embodiment is directed to a method for increasing the critical shear stress threshold of a spinning or other extrusion and fiber drawing formulation or related process, the method comprising providing a thermoplastic spinning or other extrusion and fiber drawing 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 to such formulation a starch-based polymeric material having a critical shear stress greater than that of the thermoplastic extrusion formulation. By way of example, the starch-based polymeric material itself may have a critical shear stress greater than 200 kPa or greater than 300 kPa. Even when blended as part of a masterbatch, such addition may allow the critical shear stress to be increased to a value greater than 100 kPa, such as 125 kPa or 150 kPa. In either case, the starch-based polymeric material results in an increase in the initial critical shear stress of the formulation. In one embodiment, the starch-based polymeric material may be added as part of a masterbatch (e.g., NuPlastiQ BioBlend®), where the starch-based polymeric material is already blended with a given thermoplastic material. Such a masterbatch blend may 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" may contain 50% starch-based polymeric material. By way of further example, the masterbatch BioBlend may have a critical shear stress value that is 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 is directed to a method for spinning a composition comprising a starch-based polymeric material to produce a spunbond nonwoven, meltflown thin fiber, or yarn fiber from the composition, the method comprising: providing a composition comprising a starch-based polymeric material; (a) melt-spinning a composition to produce a fiber comprising a starch-based polymer material, wherein the composition is -1 a shear viscosity of about 300 Pa·s or less at 190°C at a process shear rate of 0.05 to 0.15, which avoids the development of melt flow instabilities during melt spinning; or (b) melt-blowing the composition to produce fibers comprising a starch-based polymeric material, wherein the composition is -1 a shear viscosity of about 200 Pa·s or less at 190°C at a process shear rate of 0.15 to 1.005°C, which avoids the development of melt flow instabilities during meltblowing; or (c) spinning the composition to produce a yarn fiber having a spun diameter of about 40 μm to about 150 μm, wherein the yarn fiber comprises a starch-based polymer material, and the composition is -1 and (c) performing at least one of (a), (b), or (c) of: producing a spun yarn fiber having a shear viscosity of about 600 Pa s or less at 190°C at a process shear rate of about 1000 Pa s or less, which avoids the onset of melt flow instabilities during spinning of the yarn fiber; and drawing the as-spun yarn fiber downward from the spin diameter of the yarn fiber to a smaller diameter.

[0030] [Embodiment 2] A method includes performing (a), wherein the composition is -1 At a process shear rate of 1000 s, the shear viscosity is approximately 300 Pa s or less at 190 °C, and -1 2. The method of claim 1, wherein the polymer exhibits a shear viscosity of about 125 Pa s or less at 190°C with a spinneret shear rate of 1.

[0031] [Embodiment 3] The method of embodiment 1, wherein the method comprises carrying out (a), and the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0032] [Embodiment 4] The method of embodiment 1, wherein the method comprises performing (a), and the composition is a blend of a starch-based polymeric material and at least one thermoplastic polymer.

[0033] [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, between 200 g / 10 min and 1000 g / 10 min, or between 400 g / 10 min and 600 g / 10 min, measured at 230°C under a load of 2.16 kg.

[0034] [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 when measured at 230°C under a 2.16 kg load, a second grade having a melt flow index of less than 100 g / 10 min when measured at 230°C under a 2.16 kg load, and optionally a third grade having a melt flow index of 75 g / 10 min to 125 g / 10 min when measured at 230°C under a 2.16 kg load.

[0035] [Embodiment 7] The method of embodiment 6, wherein the at least one thermoplastic polymer further comprises an additional grade of polypropylene containing both isotactic and atactic structures, having a melt flow index of less than 1000 g / 10 min when measured at 230°C under a load of 2.16 kg.

[0036] [Embodiment 8] The method of embodiment 4, wherein the at least one thermoplastic polymer comprises a thermoplastic polymer that is itself biodegradable under industrial composting conditions.

[0037] [Embodiment 9] The method of embodiment 8, wherein the thermoplastic polymer that is itself biodegradable under industrial composting conditions is a polyester.

[0038] [Embodiment 10] The method of embodiment 1, wherein the method comprises performing (a), and the starch-based polymeric material has a moisture content, including any bound water, of 2% or less.

[0039] [Embodiment 11] The method of embodiment 1, wherein the method comprises performing (a), and the method produces fibers having a diameter of about 10 μm to about 50 μm.

[0040] [Embodiment 12] The method of embodiment 1, wherein the method comprises carrying out (a), and the starch-based polymer material is included in the composition in an amount of up to 60% by weight, up to 40% by weight, or 1% to 35% by weight.

[0041] [Embodiment 13] The method of embodiment 1, wherein the method comprises carrying out (a), and the starch-based polymer material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

[0042]

[0022] [Embodiment 14] A polymer blend for use in forming thin fibers through a spunbond process, the blend comprising: a starch-based polymeric material having a moisture content of 2% or less, including any bound water; a thermoplastic polymer material having a melt flow index configured to plasticize the starch-based polymer material; A blend in which the starch-based material is intimately dispersed within the thermoplastic polymer material.

[0043] [Embodiment 15] The blend of embodiment 14, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0044] [Embodiment 16] The polymeric starch-based polymer material is processed at a process temperature of 170°C to 210°C for at least 10 minutes. 6 ~ at least 10 7It exhibits a zero shear viscosity of Pa·s and a shear viscosity of 1000sec -1 16. The blend of embodiment 15, wherein the shear rate is reduced to 125 Pa s or less at the process temperature.

[0045] [Embodiment 17] The blend of embodiment 14, wherein the blend further comprises a compatibilizer.

[0046] [Embodiment 18] The blend of embodiment 14, wherein the starch-based polymeric material has a moisture content, including any bound water, of 2% or less.

[0047] [Embodiment 19] The blend of embodiment 14, wherein the starch-based polymer material is present in an amount of up to 60% by weight of the blend, or 1% to 35% by weight.

[0048] [Embodiment 20] The blend of embodiment 14, further comprising a thermoplastic elastomer.

[0049] [Embodiment 21] The blend of embodiment 20, wherein the thermoplastic elastomer comprises at least one of a random or block poly(propylene / ethylene) copolymer composed primarily of isotactic propylene repeat units having random ethylene distribution therein, SEBS, SBS, SIS, or another styrene block copolymer.

[0050] [Embodiment 22] The blend of embodiment 14, wherein the thermoplastic polymer material comprises a thermoplastic polymer that is itself biodegradable under industrial composting conditions.

[0051] [Embodiment 23] The blend of embodiment 22, wherein the thermoplastic polymer that is biodegradable under industrial composting conditions comprises PLA, PBAT, or another polyester.

[0052] [Embodiment 24] The blend is heated at 190 ° C and 1000 sec -115. The blend of embodiment 14, wherein the blend exhibits a shear viscosity at 125 Pa·s or less, from 40 Pa·s to 125 Pa·s, or from 40 Pa·s to 95 Pa·s.

[0053] [Embodiment 25] The blend of embodiment 14, wherein the blend exhibits a critical shear stress of at least 125 kPa while being strain hardened.

[0054] [Embodiment 26] A spunbond nonwoven fabric formed from thin fibers, the thin fibers being: a starch-based polymeric material present in an amount of up to 60% by weight; a thermoplastic polymer material having a melt flow index configured to plasticize the starch-based polymer material; A thin fiber in which a starch-based material is intimately dispersed within a thermoplastic polymer material.

[0055] [Embodiment 27] A spunbond nonwoven fabric according to embodiment 26, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having an average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0056] [Embodiment 28] A spunbond nonwoven fabric according to embodiment 26, wherein the thin fibers have a diameter of up to 50 μm, or up to 30 μm.

[0057] [Embodiment 29] A spunbond nonwoven fabric according to embodiment 26, wherein the thin fibers are not smooth but have an uneven texture.

[0058] [Embodiment 30] A spunbond nonwoven fabric according to embodiment 29, wherein the bumps constituting the bumpy texture consist essentially of a starch-based polymer material.

[0059] [Embodiment 31] A spunbond nonwoven fabric according to embodiment 26, in which the bumps that make up the bumpy texture exhibit non-uniformity relative to the smooth fiber surface, the non-uniformity being 1 to 5 μm relative to the fiber diameter.

[0060] [Embodiment 32] The spunbond nonwoven fabric of embodiment 26, wherein the thin fibers are bicomponent fibers.

[0061] [Embodiment 33] A spunbond nonwoven fabric according to embodiment 32, wherein the bicomponent fibers have a diameter of 50 μm or less and are of a sheath / core geometry, and the core or sheath comprises a starch-based polymer material.

[0062] [Embodiment 34] A spunbond nonwoven fabric according to embodiment 33, in which the sheath / core ratio is 50 / 50 to 5 / 95.

[0063] [Embodiment 35] The spunbond nonwoven fabric of embodiment 26, wherein the thermoplastic polymer material is non-biodegradable by itself and the high molecular weight starch-based material improves the biodegradability of the thermoplastic polymer material that is non-biodegradable by itself.

[0064] [Embodiment 36] A spunbond nonwoven fabric according to embodiment 35, wherein at least 20% of the thermoplastic polymer material that is non-biodegradable in itself biodegrades within 3 years under ASTM D-5338 or ASTM D-5511.

[0065] [Embodiment 37] The spunbond nonwoven fabric of embodiment 26, wherein the nonwoven fabric exhibits improved hydrophilicity, wettability, and / or absorbency compared to a nonwoven fabric formed from polypropylene without the starch-based polymer material.

[0066] [Embodiment 38] A method for increasing the critical shear stress threshold of a spinning formulation, the method comprising: providing a thermoplastic spinning formulation having an initial critical shear stress of less than 125 kPa; adding a starch-based polymer material having a critical shear stress greater than 125 kPa to a thermoplastic spinning formulation, wherein the starch-based polymer material increases the initial critical shear stress of the spinning formulation.

[0067] [Embodiment 39] The method of embodiment 38, wherein the thermoplastic spinning formulation has an initial critical shear stress of about 100 kPa.

[0068] [Embodiment 40] The method of embodiment 38, wherein the starch-based polymer material is included in an amount of at least 1% of the spinning formulation.

[0069] [Embodiment 41] The method of embodiment 38, wherein the starch-based polymer material exhibits strain hardening properties.

[0070] [Embodiment 42] A method comprises performing (b), whereby the method comprises a method for meltblowing a composition comprising a starch-based polymer material to produce thin fibers therefrom, the method comprising: providing a composition comprising a starch-based polymeric material; melt-blowing the composition to produce fibers comprising a starch-based polymer material, wherein the composition is -1 2. The method of claim 1, comprising producing a polymer having a shear viscosity of about 200 Pa s or less at 190°C at a process shear rate of about 100 Pa s or less, which avoids the onset of melt flow instability during meltblowing.

[0071] [Embodiment 43] The composition is 200s -1 At a process shear rate of 1000 s, the shear viscosity is approximately 200 Pa s or less at 190 °C, and -1 43. The method of embodiment 42, wherein the polymer exhibits a shear viscosity of about 85 Pa s or less at 190°C at a spinneret shear rate of 1000 rpm.

[0072] [Embodiment 44] The method of embodiment 42, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0073] [Embodiment 45] The method of embodiment 42, wherein the composition is a blend of a starch-based polymeric material and at least one thermoplastic polymer.

[0074] [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 between 1000 g / 10 min and 2000 g / 10 min, when measured at 230°C under a load of 2.16 kg.

[0075] [Embodiment 47] The method of embodiment 45, wherein the at least one thermoplastic polymer comprises at least two grades of polypropylene, the first grade having a melt flow index of 1000 g / 10 min to 2000 g / 10 min when measured at 230°C under a load of 2.16 kg, and the second grade having a melt flow index of 100 g / 10 min or less when measured at 230°C under a load of 2.16 kg.

[0076] [Embodiment 48] The method of embodiment 47, wherein the at least one thermoplastic polymer further comprises an additional grade of polypropylene containing both isotactic and atactic structures, having a melt flow index of less than 1000 g / 10 min when measured at 230°C under a load of 2.16 kg.

[0077] [Embodiment 49] The method of embodiment 42, wherein the starch-based polymer material has a moisture content, including any bound water, of 2% or less.

[0078] [Embodiment 50] The method of embodiment 42, wherein the method produces fibers having a diameter of about 2 μm to about 10 μm.

[0079] [Embodiment 51] The method described in embodiment 42, wherein the starch-based polymer material is contained in the composition in an amount of up to 60% by weight, up to 40% by weight, or 1% to 35% by weight.

[0080] [Embodiment 52] The method of embodiment 42, wherein the starch-based polymer material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

[0081]

[0053] A polymer blend for use in forming thin fibers through a meltblowing process, the blend comprising: a starch-based polymeric material having a moisture content of 2% or less, including any bound water; a thermoplastic polymer material having an MFI of at least 500 g / 10 min when measured at 230° C. under a load of 2.16 kg, configured to plasticize the starch-based polymer material; A blend in which the starch-based material is intimately dispersed within the thermoplastic polymer material.

[0082] [Embodiment 54] The blend described in embodiment 53, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0083] [Embodiment 55] The blend of embodiment 53, wherein the starch-based polymer material is present in an amount of 1% to 35% by weight of the blend.

[0084] [Embodiment 56] The blend is mixed for 1000 seconds -1 54. The blend of embodiment 53, wherein the blend exhibits a shear viscosity at 190°C of 85 Pa s or less.

[0085]

[0057]

[0058] [Embodiment 57] A meltblown thin fiber suitable for use in making a nonwoven web, comprising: a starch-based polymeric material present in an amount of up to 35% by weight; a thermoplastic polymer material having an MFI of at least 500 g / 10 min when measured at 230° C. under a load of 2.16 kg, configured to plasticize the starch-based polymer material; a starch-based material intimately dispersed within a thermoplastic polymer material; The meltblown thin fibers have a diameter of about 10 μm or less.

[0086] [Embodiment 58] A thin fiber according to embodiment 57, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0087] [Embodiment 59] The thin fiber described in embodiment 57, wherein the thin fiber has a diameter of about 2 μm to about 4 μm.

[0088] [Embodiment 60] A thin fiber according to embodiment 57, wherein the thermoplastic polymer material is non-biodegradable by itself and the starch-based material improves the biodegradability of the non-biodegradable thermoplastic polymer material.

[0089] [Embodiment 61] The thin fiber of embodiment 60, wherein at least 20% of the non-biodegradable thermoplastic polymer material biodegrades within 3 years under ASTM D-5338 or ASTM D-5511.

[0090] [Embodiment 62] A thin fiber according to embodiment 60, wherein the fiber exhibits improved hydrophilicity, wettability, and / or absorbency compared to a fiber formed from polypropylene without the starch-based polymer material.

[0091] [Embodiment 63] The method comprises performing (c), whereby the method comprises a method for producing yarn fibers from a composition comprising a starch-based polymer material, the method comprising: providing a composition comprising a starch-based polymeric material; spinning the composition to produce a yarn fiber having a spun diameter of about 40 μm to about 150 μm, wherein the yarn fiber comprises a starch-based polymer material, and the composition is -1 and producing a polymer having a shear viscosity of about 600 Pa·s or less at 190°C at a process shear rate of 100°C, which avoids the development of melt flow instabilities during spinning of the yarn fiber. 2. The method of claim 1, comprising: drawing the as-spun yarn fiber downward from a spun diameter of the yarn fiber to a smaller diameter.

[0092] [Embodiment 64] The method described in embodiment 63, wherein the smaller diameter after drawing the yarn fiber is 10 μm to 50 μm.

[0093] [Embodiment 65] The method of embodiment 63, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having an average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0094] [Embodiment 66] The method of embodiment 63, wherein the composition is a blend of a starch-based polymer material and at least one thermoplastic polymer.

[0095] [Embodiment 67] The method of 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 when measured at 230°C under a load of 2.16 kg.

[0096] [Embodiment 68] The method of embodiment 66, wherein the starch-based polymer material is provided in the form of a masterbatch pre-blended with a first thermoplastic polymer, and the method further comprises blending the masterbatch with a second thermoplastic polymer, wherein the first and second thermoplastic polymers have different melt flow index values.

[0097] [Embodiment 69] The method of embodiment 66, wherein the at least one thermoplastic polymer further comprises an additional grade of polypropylene containing both isotactic and atactic structures, having a melt flow index of less than 1000 g / 10 min when measured at 230°C under a load of 2.16 kg.

[0098] [Embodiment 70] The method of embodiment 63, wherein the starch-based polymer material has a moisture content, including any bound water, of 2% or less.

[0099] [Embodiment 71] The method described in embodiment 63, wherein the starch-based polymer material is contained in the composition in an amount of up to 60% by weight, or up to 40% by weight.

[0100] [Embodiment 72] The method of embodiment 71, wherein the starch-based polymer material is included in the masterbatch in an amount of up to 60% and the starch-based polymer material is included in the composition to be spun in an amount of up to 40% by weight.

[0101] [Embodiment 73] The method of embodiment 63, wherein the starch-based polymer material has a weight average molecular weight of 3 million g / mol to 20 million g / mol.

[0102]

[0072] [Embodiment 74] A polymer blend for use in forming a yarn fiber, the blend comprising: a starch-based polymeric material having a moisture content of 2% or less, including any bound water; a thermoplastic polymer material configured to plasticize the starch-based polymer material, the thermoplastic polymer material having a melt flow index of 10 g / 10 min to 100 g / 10 min when measured at 230°C under a load of 2.16 kg; A blend in which the starch-based material is intimately dispersed within the thermoplastic polymer material.

[0103] [Embodiment 75] The blend described in embodiment 74, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0104] [Embodiment 76] The blend of embodiment 74, wherein the starch-based polymer material is present in an amount of up to 60% by weight of the blend.

[0105] [Embodiment 77] The blend described in embodiment 74, wherein the thermoplastic polymer material having a melt flow index of 10 g / 10 min to 100 g / 10 min comprises at least two thermoplastic polymer materials, a first of which has a melt flow index of about 10 g / 10 min to about 50 g / 10 min, and a second of which has a melt flow index of about 75 g / 10 min to about 125 g / 10 min.

[0106] [Embodiment 78] A yarn fiber, a starch-based polymeric material present in an amount of up to 60% by weight; a thermoplastic polymer material having a melt flow index configured to plasticize the starch-based polymer material; A yarn fiber in which a starch-based material is intimately dispersed within a thermoplastic polymer material.

[0107] [Embodiment 79] The yarn fiber of embodiment 78, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol, or at least 5 million g / mol.

[0108] [Embodiment 80] A thread fiber described in embodiment 78, wherein the thread fiber has a diameter of about 10 μm to about 50 μm.

[0109] [Embodiment 81] The yarn fiber of embodiment 78, wherein the starch-based polymer material is present in an amount of 1% to 40% by weight.

[0110] [Embodiment 82] The yarn fiber of embodiment 78, wherein the thermoplastic polymer material is non-biodegradable by itself, and the starch-based polymer material enhances the biodegradability of the non-biodegradable thermoplastic polymer material.

[0111] [Embodiment 83] The yarn fiber of embodiment 82, wherein at least 20% of the non-biodegradable thermoplastic polymer material biodegrades within 3 years under ASTM D-5338 or ASTM D-5511.

[0112] [Embodiment 84] The yarn fiber of embodiment 78, wherein the fiber exhibits improved hydrophilicity, wettability, and / or absorbency compared to a fiber formed from polypropylene without the starch-based polymer material.

[0113] [Embodiment 85] A method comprises carrying out (a), whereby the method comprises a method for spinning a composition comprising a starch-based polymer material to produce a spunbond nonwoven fabric therefrom, the method comprising: providing a composition comprising a starch-based polymeric material; melt-spinning the composition to produce a fiber comprising a starch-based polymer material, wherein the composition is -1 and producing a polymer having a shear viscosity of about 300 Pa s or less at 190°C at a process shear rate of about 100 Pa s or less, which avoids the onset of melt flow instabilities during melt spinning.

[0114] The features of any of the above embodiments may be combined with each other in any combination.

[0115] While the NuPlastiQ starch-based polymer described herein is one example of a starch-based material that can provide the advantages described herein, it will be understood that the scope of the present invention extends broadly to other starch-based materials (e.g., developed sometime in the future) that may exhibit similar properties, or even materials that may be synthesized from starting materials other than starch, that may achieve similar results due to the presence of the same or similar chemical structure or functional groups as the starch-based materials described herein. For example, if a material having a similar or identical chemical structure to NuPlastiQ was synthesized (e.g., in a reactor) starting from a non-starch material, it would still be within the scope of the present invention.

[0116] Further features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiments. [Brief explanation of the drawings]

[0117] A more particular description of the invention briefly described above will be made by reference to specific embodiments thereof, as illustrated in the accompanying drawings. It being understood that these drawings depict only typical embodiments of the invention and therefore should not be considered limiting of its scope; the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings.

[0118] [Figure 1] 1 shows viscosity versus shear rate (flow curve) for Sample 984, an exemplary high molecular weight starch-based polymer material prepared as described in the Examples. [Figure 2] 1 shows flow curves for various high molecular weight starch-based materials formed from different starting starch materials. [Figure 3] 10 illustrates additional flow curves for other exemplary high molecular weight starch-based materials formed in accordance with the present invention. [Figure 4] 1 presents data regarding the melt flow instability characteristics of exemplary prepared high molecular weight starch-based materials. [Figure 5] 1 shows flow curves for exemplary high molecular weight starch-based polymeric materials and a constant shear stress line of 100 kPa (a typical manifestation of instability for PP). [Figure 6] For example, additional flow curves for various additives (e.g., PP thermoplastic diluents with various MFI values ​​from 35 to 1600 g / 10 min) are shown. [Figure 7] Additional flow curve data for various prepared and tested formulations is provided. [Figure 7A] Additional flow curve data for various prepared and tested formulations is provided. [Figure 8] 1 shows an exemplary fiber formed as described in the Examples. [Figure 9]1 shows an exemplary fiber formed as described in the Examples. [Figure 10] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 11] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 12] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 13] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 14] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 15] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 16] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 17] 1 illustrates various bicomponent fibers formed as described in the Examples. [Figure 18] Figure 1 shows the flow curve of an exemplary formulation containing 25% high molecular weight starch-based material, 50% 500 MFI PP, 21% 35 MFI PP, and 4% compatibilizer at 190°C. Low shear data was obtained using a cone and plate rheometer. [Figure 19] 1 shows spin envelope plots for exemplary polypropylene compositions of 35 MFI and 100 MFI at 195°C and 225°C. [Figure 20] 1 shows Rheotens plots for various exemplary and comparative compositions. [Figure 21] 1 illustrates schematically an exemplary spunbond process. [Figure 22] 1 illustrates schematically an exemplary meltblowing process. [Figure 23] 1 schematically illustrates an exemplary yarn production process. DETAILED DESCRIPTION OF THE INVENTION

[0119] I. Definition All publications, patents, and patent applications cited herein, whether supra or infra, are herein 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. Such incorporation by reference includes the prosecution history of Applicant's prior patents, many of which have been granted / issued.

[0120] The term "comprising," which is synonymous with "including," "containing," or "characterized by," is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

[0121] The term "consisting essentially of" limits the scope of a claim to the particular materials or steps of the claimed invention and "that do not materially affect the basic and novel characteristics."

[0122] As used herein, the term "consisting of" excludes any element, step, or ingredient not specified in the claim.

[0123] As used in the context of describing features of the present invention (particularly in the context of the claims that follow), the terms "a," "an," "the," and similar referents should be construed to encompass both the singular and the plural, unless otherwise specified herein or clearly contradicted by context. Thus, for example, reference to "starch" may include one, two, or more starches.

[0124] As used herein, "nonwoven" refers to a cloth-like material made from staple and / or long fibers that are bonded together, for example, by thermal, mechanical, chemical, or solvent treatment. Such materials are not woven or knitted, but are formed from a web of such fibers that are entangled or otherwise bonded together.

[0125] Unless otherwise specified, all percentages, ratios, parts, and amounts used and described herein are by weight, including molecular weight, i.e., weight average molecular weight to number average molecular weight.

[0126] As will be understood by those skilled in the art, any number, percentage, ratio, or other value set forth herein may include that value and other values ​​that are about or approximately the stated value. Accordingly, a stated value should be interpreted broadly enough to encompass values ​​at least sufficiently close to the stated value and / or values ​​that are rounded to the stated value to perform the desired function or achieve the desired result. The stated value includes at least expected variations in typical manufacturing processes and may include values ​​within 25%, 15%, 10%, 5%, 1%, etc., of the stated value.

[0127] All numbers expressing quantities of ingredients, components, conditions, and the like used in the specification and claims should be understood as being modified in all instances by the term "about." Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0128] Several ranges are disclosed herein. Additional ranges may be defined between any of the values ​​disclosed herein as examples of particular parameters. All such ranges are contemplated and within the scope of the present disclosure. Furthermore, the recitation of ranges of values ​​herein is intended to serve as a shorthand method of individually referring to each individual value within the range. Unless otherwise specified herein, each individual value is incorporated herein as if set forth individually herein.

[0129] As used herein, the phrase "free" or similar phrases means that the composition contains 0% of the stated component, i.e., the component has not been intentionally added to the composition. However, it will be understood that such components may form accidentally under appropriate circumstances and may be accidentally present in another included component, for example, as an accidental contaminant.

[0130] As used herein, the phrase "substantially free" or similar phrases means that the composition preferably contains 0% of the recited component, although it is understood that very low concentrations may be present, for example, due to accidental formation, accidental contamination, or even intentional addition. Such components, if present at all, may be present in amounts 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%.

[0131] The term "non-biodegradable," as used herein with respect to a material, means that a natural material (without additives added to make it biodegradable) does not decompose (particularly biodegrade) to a significant extent, e.g., to carbon dioxide and / or methane, within a reasonable time limit (e.g., 1, 2, 3, or 5 years) when exposed to various typical disposal conditions, such as marine, landfill, industrial, or other composting conditions, or to specific ASTM conditions designed to evaluate biodegradability under a particular set of conditions (e.g., ASTM D-5511, D-5526, D-5338, D-6691). However, given sufficient time and exposure to conditions of sunlight, oxygen, and decomposing microorganisms, it is understood that most polymeric materials (e.g., even those typically considered "non-biodegradable") will eventually decompose or even biodegrade, usually to some limited extent, over an extended period of time (e.g., centuries).

[0132] The term "biodegradable" as used herein with respect to a material means that under "ideal" biodegradation conditions (e.g., anaerobic digester, industrial compost, etc.), such as those under various ASTM biodegradation tests (e.g., ASTM D-5511, D-5526, D-5338, or D-6691), the materials described herein will significantly biodegrade (e.g., greater than 50%) into base molecules such as carbon dioxide, methane, and / or water within a reasonably limited time frame (e.g., 5 years, 3 years, 2 years, 1 year, etc.).

[0133] The term "modified," as used, for example, when describing "modified starch," refers to physical and / or chemical modification, including conversion of the starting starch material to one containing a lower molecular weight. Applicant's NuPlastiQ materials may be considered to include "modified" starches. Starches that may not necessarily fall within the description of the term "modified" may also be suitable, for example, if they otherwise exhibit the properties described herein. Such mechanical and / or chemical modification may include modification of the amylopectin starch component to a more linear amylose structure.

[0134] For example, some literature suggests that amylose (15-30% of starch units) may contain chains with molecular weights of about 40,000-340,000 daltons, with the chains containing 250-2000 anhydroglucose units. Amylose is an unbranched chain wound in a helical shape.

[0135] Amylopectin (70-85% of the units in starch) contains chains with a high molecular weight of 80,000,000 daltons. It will be understood that the above descriptions of amylose and amylopectin are merely exemplary and that starches with different properties may also be suitable for use.

[0136] It will be understood that the descriptions herein are merely exemplary, and that many 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 available from Applicant. Determination of molecular weight can be by any desired process, for example, any of a variety of size exclusion chromatography techniques (e.g., gel permeation chromatography ("GPC") or gel filtration chromatography ("GFC")).

[0137] Unless otherwise indicated, melt flow index values ​​are in units of g / 10 min under standard conditions (e.g., 230°C under a 2.16 kg load for polypropylene, 190°C under a 2.16 kg load for polyethylene and other materials).

[0138] With respect to various standardized tests (e.g., ASTM or other tests), reference to any such standard will be understood to refer to the most recent update (if any) of such standard unless otherwise indicated. Any such referenced standard is incorporated herein by reference in its entirety.

[0139] II. Introduction The present disclosure is directed, inter alia, to methods for successfully spinning (e.g., spunbond, meltblown, yarn, or similar spinning processes) compositions comprising starch-based polymeric materials, which may be of very high molecular weight. In one embodiment, the starch-based polymeric materials may have a relatively high molecular weight, e.g., a molecular weight of greater than 2, 3, 4, or 5 million, such as at least 3 to 20 million, or 5 to 16 million. Such values ​​may represent weight average molecular weights. Number average molecular weights may be greater than 1, 2, 3, 4, or 5 million, such as 3 to 12 million, 3 to 10 million, or 5 to 7 million. The starch material from which the starch-based polymeric material is formed (e.g., formed from starch and plasticizer in a reactive extrusion process) can similarly have a weight average molecular weight of 1 million, 2 million, 3 million, 4 million, or greater than 5 million, such as 3 million to 10 million, or 5 million to 7 million. The Mw to Mn ratio (polydispersity) for the starting starch or the finished starch-based polymeric material can be at least greater than 1, such as 1 to 2, 1 to 3, 1 to 4, or even higher.

[0140] For example, to be suitable for a spunbond process, a composition must be capable of being spun into thin fibers, e.g., having a diameter of 30 μm or less, e.g., less than 25 μm. Of course, the process is similarly suitable for forming larger fibers, up to any desired size. For example, up to 50 μm, up to 100 μm, or even larger may be desirable. Meltblown fibers have even more stringent fiber size requirements, e.g., typically less than 5 μm in diameter (e.g., 2-10 or 2-4 μm). By way of example, yarn fibers may initially be formed at 40 μm to 150 μm, or 40 μm to 100 μm (e.g., about 60 μm), followed by drawing (e.g., hot drawing) the spun yarn to a smaller size, e.g., 10 μm to 50 μm, or 10 μm to 30 μm (e.g., about 20 μm). The present disclosure describes formulations and processes that can be used for any of these processes.

[0141] Although contemplated grades of NuPlastiQ as starch-based polymeric materials may have very high molecular weights (e.g., at least 3 million, 3-10 million, 5-7 million, 7-9 million, or even 10-18 million), Applicants have surprisingly found that it is possible to spin fibers comprising a significant fraction of such high molecular weight material, at least in part due to certain properties exhibited by this material. For example, this starch-based material has a very high molecular weight (and therefore a very high zero shear viscosity (Eta-0, η)), as well as a correspondingly high shear viscosity η. s and extension or extension η E Although the starch-based material exhibits a high shear sensitivity, the applicant has discovered that the material also exhibits properties that allow it to still be spun into yarns, even under process conditions achievable on commercial spunbond, meltblown, or yarn production lines, where certain choices are made in operating parameters and composition formulations. For example, the applicant has discovered that the starch-based material exhibits excellent shear sensitivity, such that the zero shear viscosity is very high (e.g., approximately at least an order of magnitude greater than conventional TPS materials, 10 6 or 10 7 Although shear viscosity can be higher than commercial production line shear rates (e.g., 200-1500 s), especially when coupled with other "handles" or "levers" that can be adjusted, as described below, -1 ) can be rapidly reduced.

[0142] For example, in addition to excellent shear sensitivity, starch-based polymeric materials have also been found to exhibit excellent responsiveness to thermoplastic diluents and plasticizers; the addition of polypropylene or similar thermoplastic polymers with higher melt flow indexes dramatically improves flow properties. The MFI or other properties of the diluent selected for use in diluting and plasticizing the starch-based polymeric material so that it is spinnable under the conditions described herein may 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 may be selected depending on the particular process being used.

[0143] Additionally, starch-based materials exhibit excellent response to extrusion temperature in that the viscosity decreases significantly as the extrusion temperature increases. Therefore, to further plasticize the blend, the extrusion temperature may be increased to a given process shear rate (e.g., about 200 s for many spinning processes, such as spunbond, meltblown, or yarn) with a given spinneret shear rate. -1 By providing spinning conditions within a specific 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) and where an effective amount of a high melt flow index thermoplastic material is blended with the starch-based polymeric material, the composition can be processed through a given system while avoiding melt flow instabilities. The actual shear rate will vary based on the die diameter, flow rate (e.g., GMH: grams per minute per hole), and material density. Generally, spinneret shear rates range from 400 to 10,000 s across a variety of yarn, spunbond, meltblown, or similar melt extrusion fiber spinning processes. -1 The range may be:

[0144] For example, in a spunbond or meltblown process, the composition is spun for 1000 sec -1The shear viscosity may be about 125 Pa·s or less, or 95 Pa·s or less (e.g., 50 to 65 Pa·s or less) at shear pressure. Under such conditions, spunbond fibers having a diameter of at least 10 μm, such as 15 μm to 100 μm, 10 μm to 50 μm, or 15 μm to 30 μm, can be produced. With appropriate diluent / plasticizer selection, meltblown fibers having a diameter of 5 μm or less, such as 2 to 10 μm, or 2 to 4 μm, can be produced. With appropriate diluent-plasticizer selection, yarn fibers having diameters of 40 μm or greater, such as 40-150 μm, 40-100 μm, 40-80 μm, such as about 60 μm, can be produced, and can be drawn down to smaller final diameters (e.g., 10 μm-50 μm, 10 μm-30 μm, such as about 20 μm) after initial fiber formation in heated draw rolls typically employed in yarn processes. Of course, spunbond, meltblown, and yarn processes are merely exemplary, and other similar fiber spinning processes can be used to produce fibers of various diameters using the principles detailed herein.

[0145] In either case, it is surprising that such a "handle" or "lever" is sufficient to achieve fiber spinning in which the composition contains a substantial fraction of very high molecular weight starch-based polymeric material. This is possible even when no strain-hardening additive is specifically added to the composition. For example, Applicant has further observed that the currently contemplated starch-based polymeric materials employed appear to be strain-hardening themselves, rather than strain-thinning, as other thermoplastic starch materials appear to be.

[0146] Examples of suitable high molecular weight starch-based materials are available from BioLogiQ under the trade name "NuPlastiQ," particularly those with the very high molecular weights described herein. Some properties of NuPlastiQ materials (particularly NuPlastiQ GP and NuPlastiQ CG) are described in other U.S. patent applications of various applicants (e.g., U.S. Patent Application No. 16 / 925,705 (21132.27.1.1)), which is incorporated herein by reference in its entirety. Many properties of the high molecular weight starch-based materials described herein may be similar to those described above for NuPlastiQ GP and NuPlastiQ CG. Other starch-based polymers may also be suitable for use, for example, where such materials may exhibit at least some of the other key properties described herein that enable such materials to be spun.

[0147] At least when 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 polymer / NuPlastiQ blends containing polymers previously considered non-biodegradable, such as polypropylene or polyethylene, a substantial portion or all of the carbon atoms in the blended product (including those of PP and PE) can be converted by microorganisms to CO and / or CH much more rapidly. In other words, NuPlastiQ can render polypropylene or polyethylene biodegradable when blended with polypropylene or polyethylene in a homogeneous mixture in which NuPlastiQ is intimately dispersed in the polypropylene or polyethylene. In addition, when blended with polymers previously considered compostable or biodegradable, such as PLA or others (e.g., PBAT, PBS, PCL, PHA, etc.), the rate and / or extent of biodegradation of such other polymers can be further improved under any given conditions by the addition of NuPlastiQ starch-based materials. The rate of microbial conversion depends on several factors, such as the thickness of the structure, other forms of the article (e.g., powder vs. larger continuous pieces), number of microorganisms, type of microorganism, environmental conditions (e.g., pH, humidity, temperature, etc.), ratio of NuPlastiQ starch-based material to other polymers in the product, type of plastic in the blend, and strength of carbon bonds in the plastic.

[0148] Thus, the present embodiments enable thin fiber formation from high molecular weight starch materials when used in, for example, spunbond processes, meltblown fiber process yarns, or other fiber melt spinning processes, by blending very high viscosity starch materials (e.g., having viscosity properties that may be at least an order of magnitude greater than the starches described above for use in thin fiber formation) with thermoplastic diluent polymer materials in a manner that ensures that desired rheological properties are obtained (e.g., shear stress is maintained below a critical threshold) when such compositions are processed through spinneret pre-extrusion at commercial line shear rates, which allows such starch compositions to be advantageously incorporated into fibers otherwise formed from conventional thermoplastic materials, thus improving the sustainable properties of such fibers and nonwoven webs formed therefrom.

[0149] In addition to providing such formulations with improved sustainable biological content, the present embodiments are also directed to such products (e.g., compositions, thin fibers, nonwoven webs formed therefrom, and any articles incorporating such fibrous structures) that offer one or more mechanical or physical benefits associated with the inclusion of starch-based polymeric materials within the composition. For example, the incorporation of currently contemplated starch-based materials may actually improve the critical shear stress threshold properties of the thermoplastic polymeric materials with which they are compounded or otherwise blended, providing manufacturers with additional flexibility in the parameters under which spunbond, meltblown, yarn, or similar fiber production processes are carried out, for example, using conventional resins. For example, a typical polypropylene composition exhibits a critical shear stress of approximately 100 kPa, above which melt flow instability occurs, making it impossible to effectively spin usable fibers under conditions above the critical shear stress. The high molecular weight starch-based polymeric materials of the present invention actually increase the applicable critical shear stress threshold, allowing the composition to be effectively processed at higher shear stresses, e.g., 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. Such is a distinct advantage, allowing for the production of thinner fibers, faster line speeds, etc.

[0150] Finally, in addition to the possibility of providing bicomponent or other multicomponent fiber geometries, the present disclosure may provide fibers having unusual fiber morphology characteristics, e.g., "ridges" provided thereon, which may comprise or consist essentially of a starch component (or another component of the compounded blend from which the fiber is formed). Such ridges may vary (i.e., their radius or thickness) from the normal, generally circular fiber radius or diameter by, e.g., 1 to 4 μm for fibers having a thickness ("diameter") of 15 to 30 μm.

[0151] III. Exemplary Articles and Methods The present blends and processes may 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 an example of such a material, although other thermoplastic polymers may also be suitable for use. By way of example, the selected thermoplastic polymer may have a melt flow index (MFI) of at least 35 (e.g., 35-2000, such as 35-1750, 35-1550, 35-1250, 35-1000, 35-750, or 35-500). For polypropylene, such MFI values ​​may be at 230°C under a 2.16 kg load. For polyethylene, such MFI values ​​may be at 190°C under a 2.16 kg load. The MFI or other properties of the diluent material employed may depend on whether the formulation is to be used in a spunbond, meltblown, yarn, or other thin fiber extrusion / spinning process, and may require a sufficiently low shear viscosity (e.g., 200 s) for the formulation to pass through the system. -1Selection is made to provide a formulation with the rheological properties necessary to ensure a melt flow index (BPI) as described herein (measured at 190°C using a 1 mm diameter die with L / D=30) and a viscosity to avoid melt flow instability, particularly through the high shear conditions associated with spinnerets. In one embodiment, two or more such diluent materials may be used, such as a thermoplastic polymer material having a melt flow index of 35 and another having a melt flow index of 100-2000, 100-1750, 100-1550, 100-1250, 100-1000 (e.g., 100-500, or 400-600). In one embodiment, a first diluent material may be pre-blended with a starch-based polymer material, for example, in a NuPlastiQ or other masterbatch. Such a first diluent material included in the masterbatch may have a relatively low MFI value, e.g., 200 or less, such as 35-100, or 100 or less. Such a masterbatch may be blended with a second diluent material during processing, the choice of which depends on the process being employed (e.g., spunbond, meltblown, yarn, etc.). In one embodiment, the second diluent material may have a higher MFI value than the first diluent material. Of course, it is also possible to provide a fully diluted composition without the use of any intermediate masterbatch.

[0152] While polypropylene is one example of a material particularly suitable for use in such processes, other thermoplastic materials may also be suitable for use, including, but not limited to, polyethylene, other polyolefins, polyesters such as PLA and PBAT. For example, some polyesters may be particularly useful in forming yarn fibers. Examples of suitable thermoplastic materials may have MFI values ​​greater than those of starch-based polymer materials, as described herein. Such MFI values ​​are typically reported in g / 10 min under standardized conditions (e.g., ASTM D-1238 or other relevant standards). Such values ​​are higher than the melt index of starch-based polymers. By way of example, the MI for an exemplary high molecular weight NuPlastiQ material, as shown in Table 1, is 6 g / 10 min at 170°C under a load of 21.6 kg. Such materials are very viscous and barely flow under standardized test conditions. As a practical matter, it is very difficult to measure MFI at the standard temperature of 190°C using the standard 2.16 kg weight because the value would be very low and a significant fraction of any such flow would be due to decomposition of the NuPlastiQ material under such conditions, so any measured values ​​are likely to be very inconsistent. Because the NuPlastiQ material is stable and consistently accurate measurements are possible at 170°C under a higher load of 21.6 kg, this is the reported condition for the values ​​shown in Table 1.

[0153] Thermoplastic materials used as diluents to improve the rheological properties of starch-based materials can be sourced from traditional petrochemical "fossil fuel" sources or so-called "green" or renewable sources (e.g., bioPE, bioPET, PLA, other polyesters, etc.). Petroleum fossil fuel versus renewable sources can be distinguished from one another using various analytical methods, one of which is the detection of C within the material. 14 Against C 12 As an example, a petroleum fossil fuel source may involve determining the ratio of C 14Materials that do not contain ingredients but are sourced from renewable or sustainable sources (renewable and sustainable are used interchangeably herein) (even the same material, such as "green" PE vs. conventional fossil fuel PE) are considered C 14 The starch-based polymeric material and thermoplastic diluent material having the desired MFI properties can be provided in any desired form, such as pellets, powders, aggregates, slurries, and / or liquids.

[0154] The present compositions can be used to form thin fibers for use in the manufacture of any desired article through any of a wide variety of thin fiber melt spinning processes. Examples of such processes include, but are not limited to, various spunbond, meltblowing, yarn, and other processes, the details of which will be apparent to those skilled in the art. Such thin fibers can be used to produce various nonwoven structures, carded fibers (e.g., in the case of yarn), and the like. Thin fibers can also be produced, wound, and then provided as an intermediate material from which fabrics or other articles can be formed. Such fabrics can be nonwoven, woven, or knitted fabrics, and the like. It will be apparent that thin fibers as described herein, including starch-based polymeric materials, can have a wide variety of uses. When the composition includes a starch-based polymeric material and one or more thermoplastic polymeric materials, particularly those having desirable melt flow index properties, such components can be blended together (e.g., with or without a compatibilizer) prior to spinning. For example, the materials can all be pre-blended together and then fed into an extruder.

[0155] In one embodiment, the starch-based material may be provided in the form of a masterbatch, which already contains a thermoplastic diluent material and, optionally, a compatibilizer. The masterbatch may be blended with additional thermoplastic diluent materials in an extruder during the same process in which spinning occurs. For example, a masterbatch may contain a starch-based polymer material, a compatibilizer, and a first thermoplastic diluent material having a desired MFI value. Such a masterbatch may then be further blended with another or additional thermoplastic polymer diluent material (e.g., having a desired MFI) immediately prior to spinning. It will be apparent that numerous possibilities exist for such blending or compounding. For example, if the final blending or compounding occurs during the spinning process, one or more thermoplastic polymers having specifically selected melt flow index characteristics and the starch-based material may be fed into the extruder (e.g., into one or more hoppers thereof). The different materials can be fed into the extruder in the same chamber, in different chambers, at approximately the same time (e.g., through the same hopper), or at different times (e.g., through different hoppers, one introduced into the extruder along the screw earlier than the other). It will be apparent that many possibilities exist for such a process.

[0156] It will be apparent that many blending possibilities are possible. In one embodiment, any provided masterbatch containing a starch-based material may already contain at least a portion of one or more thermoplastic polymers having specifically selected melt flow index values. For example, if the thermoplastic polymer contains two or more different polymers with different melt flow index values ​​(e.g., 35 and 500, or 100 and 500, or 35 and 1550, etc.), the masterbatch may already contain one such thermoplastic polymer already blended with the starch-based material. A compatibilizer may also typically be present in such a masterbatch. As an example, if the final composition used to spin thin fibers is intended to contain 25% by weight of a starch-based polymer, 4% by weight of a compatibilizer, and 71% by weight of a thermoplastic polymer having a specific melt flow index value, the masterbatch may contain 50% by weight of the starch-based material, 8% by weight of a compatibilizer, and 42% by weight of one or more of the thermoplastic polymers. As an example, the masterbatch may then be blended 1:1 (or other blend ratio) with an additional thermoplastic polymer having a particularly desired melt flow index value to achieve the final composition from which thin fibers are spun.

[0157] An important feature of the present compositions may be that the selected starch-based material has a higher molecular weight than many of the starch-based materials described above as suitable for fiber spinning. For example, previous work in incorporating starch-based materials into fibers has focused on efforts to increase the amylose content of the starch-based material (e.g., through enzymatic debranching) or otherwise reduce the molecular weight of the starch-based material so that the composition has rheological properties that would allow it to be spun. Even with such modifications, U.S. Patent Application Publication No. 2019 / 0330770 notes that, although such blends could be spun, the rheological properties of such blends were still incompatible with manufacturing processes operating at commercial shear rates and commercial line speeds (e.g., 500-1000 m / min or higher), and that fibers having such starch-containing compositions would break when the production line was run at such speeds. Such adaptations to reduce line speeds may also actually reduce the strength of the fibers formed, which is, of course, undesirable. Additionally, the compositions described in such previous attempts contain significant moisture. Removal of such residual moisture (most of which exists as bound water attached to starch molecules) can be difficult, and the presence of residual water can undesirably affect various material properties or be otherwise undesirable. In contrast to such previous attempts in which bound water was retained, in at least some embodiments as contemplated herein, the moisture content of high molecular weight starch-based materials is minimal, e.g., 2% or less, or 1.5% or less, including any bound water.

[0158] Using the same reactive extrusion process by which commercial grades of NuPlastiQ were previously available, the applicant has now prepared high molecular weight NuPlastiQ, demonstrating that it can be incorporated into compositions suitable for spinning thin fibers. Such NuPlastiQ materials suitable for thin fiber spinning are available from the applicant. In any case, the starch-based polymeric materials currently described and contemplated exhibit significantly higher molecular weight values ​​than any starch-based materials previously shown to be spinnable. Previous attempts described in the literature to spin thin fibers from compositions containing starch-based materials have only succeeded in spinning such fibers in which the starch-based component had a molecular weight (weight average molecular weight) of up to about 1 million, and in some cases up to approximately 2 million. For example, StarDri-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 method used to measure the molecular weight of the starch-based polymeric materials described herein.

[0159] Among some exceptions in the art, U.S. Patent Application Publication No. 2019 / 0330770 reportedly includes examples using starch-based materials having a molecular weight of 2.9 million, where the starch comprises 30% or less by weight of the blend, but applicants are unaware of successful spinning of fibers from compositions containing a significant fraction (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 significantly higher weight average molecular weights, such as at least 3, 4, or 5 million daltons. This is not surprising given that viscosity increases exponentially with molecular weight, making compositions with very high viscosities poor candidates for thin fiber spinning. For example, at least one of the present inventors has believed that it would be impossible to prevent thin fibers from compositions containing a significant fraction of starch-based polymeric materials having high molecular weights as described herein (see, e.g., Tables 3A and 3B), especially at commercial line speeds (where the shear rate and applied shear stress approach critical values ​​at which melt instability occurs). The present disclosure describes how to achieve such.

[0160] The starch-based material may 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, sorghum starch, or algae starch. In some embodiments, a mixture of different types of starches may be used, as described in Applicant's previous applications, which have been incorporated by reference. In other embodiments, only a single starch may be used in forming the starch-based material. Starch-based materials are typically formed using a plasticizer in addition to starch. In one embodiment, the material from which the starch-based polymeric material is formed may consist essentially of starch and a plasticizer. Additional ingredients, such as odor-reducing agents or other adjuvants, may optionally be included. The use of odor-reducing agents (e.g., vanillin) is described in Applicant's U.S. Patent No. 10,920,044 (21132.12.1), which is incorporated by reference in its entirety. Once the starch-based polymeric material is formed from the starch and plasticizer, a compatibilizer or other adjuvant may be compounded into a masterbatch comprising the starch-based polymeric material and a thermoplastic diluent polymer (e.g., polypropylene having a selected MFI value).

[0161] The starch-based material can be formed mostly 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 final starch-based material can be attributable to one or more starches. Other than a negligible water content (e.g., 1.5 to 2% or less), essentially the remainder of the final starch-based material can be or can be attributable to plasticizers (e.g., glycerin). If an odor-reducing agent is included, it is typically present in very small amounts (e.g., less than 1%, often less than 0.1%, such as 1 to 100 or 1 to 10 ppm). The above percentages can represent the percentage of starch relative to the starting material from which the starch-based material is formed, or that portion of the final starch-based material that is derived from or attributable to starch (e.g., at least 65% of the starch-based material can be attributable to (formed from) starch as a starting material). Substantially the remainder can be attributable to plasticizer.

[0162] By way of example, the material from which the starch-based material is formed can contain at least 12%, at least 15%, at least 18%, at least 20%, at least 22%, no more than 35%, no more than 32%, no more than 30%, no more than 28%, or no more than 25% by weight of plasticizer. Such percentages can represent the fraction of the finished starch-based material that is derived from or attributable to the plasticizer.

[0163] Exemplary plasticizers include glycerin, polyethylene glycol, sorbitol, polyhydric alcohol plasticizers, non-hydroxyl hydrogen bond-forming organic compounds, anhydrides of sugar alcohols, animal proteins, vegetable proteins, fatty acids, phthalates, dimethyl and diethyl succinates and related esters, glycerol triacetate, glycerol monoacetate and diacetate, glycerol mono-, di-, and tripropionate, butanoates, stearates, lactates, citrates, adipates, stearates, oleates, other acid esters, or combinations thereof. Glycerin may work particularly well.

[0164] The finished starch-based material may contain 5% by weight or less, 4% by weight or less, 3% by weight or less, 2% by weight or less, 1.5% by weight or less, 1.4% by weight or less, 1.3% by weight or less, 1.2% by weight or less, 1.1% by weight or less, or 1% by weight or less of water, including bound water. By way of example, patent references generally describing the modification of starch-based polymeric materials to make them suitable for spinning contain significant bound water (e.g., 5-16%), much higher than the moisture content typically present in the starch-based materials contemplated herein. Furthermore, while lower moisture contents may be described in some references generally describing starch-based polymeric materials (e.g., for use in films), no effort has been made to modify such materials to make them suitable for spinning, and due to the highly demanding requirements placed on such, simply replacing one such material with another is not a straightforward operation, especially when those materials specifically formulated to be spinnable contain significant moisture content.

[0165] Additional details regarding the proportions of starch and glycerin or other plasticizer used in forming the starch-based material are provided in other patent applications of the applicant previously incorporated by reference herein. The physical properties of NuPlastiQ GP are set forth in Table 1 below. Properties for the described high molecular weight starch-based polymers used herein to spin thin fibers are expected to be 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 moisture content may be representative of the high molecular weight starch-based polymer materials contemplated for use in the present embodiments. Any of these properties may be measured by any of a variety of ASTM or other standards, as would be understood by one skilled in the art. Some properties may vary slightly from the values ​​shown in Table 1 (e.g., ±25% or ±10%). [Table 1]

[0166] The weight-average molecular weight, as described herein, may be relatively high, e.g., greater than 2 million, greater than 3 million, greater than 4 million, or greater than 5 million, such as 3 million to 20 million, 5 million to 18 million, or 5 million to 16 million. Such values ​​may be determined via any of a variety of suitable size-exclusion chromatography methods, e.g., gel permeation chromatography (GPC) and / or gel permeation chromatography (GFC). The values ​​in the examples herein were determined via size-exclusion chromatography with multi-angle light scattering (MALS) and refractive index (RI) detection. In either case, such molecular weight values ​​are significantly higher than starch-based materials already made to be spinnable. The starch from which the starch-based polymeric material is made may similarly have a very high molecular weight, as described herein. That is, it will be understood that in other embodiments, it may be possible to use starting starch or finished starch-based polymeric materials having lower weight-average molecular weights, e.g., less than 2 million, or perhaps even less than 1 million. Viscosity is strongly related to molecular weight. Due to their high molecular weight, presently contemplated starch-based materials also exhibit significantly higher viscosity characteristics than starch-based materials previously used in spinning fibers. For example, even at a given process temperature (e.g., 170-195°C) or other relevant temperature, the zero-shear viscosity can be at least an order of magnitude greater than starch-based materials previously used in spinning fibers.

[0167] Some of the properties may be similar to other thermoplastic starch materials, while other properties may be quite different from typical starch-based materials. For example, the density of NuPlastiQ materials is particularly high, e.g., 1 g / cm 3 More than, at least 1.1g / cm 3 , at least 1.2 g / cm 3 , or at least 1.25 g / cm 3 , (e.g., 1.4 g / cm as shown in Table 1 above) 3). Various other properties may also differ substantially from superficially similar-looking starch-based polymer materials. As described, NuPlastiQ materials have low moisture content. As the material absorbs moisture, it exhibits plastic behavior and becomes flexible. When removed from the humid environment, the material dries and becomes rigid again (e.g., again exhibiting a moisture content of less than about 1.5%). Any moisture present in NuPlastiQ (e.g., in pellet form) may be released in the form of steam during processing. As a result, thin fibers, nonwoven webs, or other articles produced from contemplated starch-based materials may exhibit even lower moisture contents because the thermoplastic diluent material will typically contain no or negligible water, and substantially all of the water in the starch-based polymer material can typically be released during production of the desired article.

[0168] Low moisture content in any starch-based material can be important, as significant moisture content can hinder the ability to process the composition at high temperatures. While Applicant has observed relatively hydrophobic properties for films of blends containing NuPlastiQ (e.g., as determined by dyne pen testing), the bicomponent fibers of the present invention appear to exhibit more hydrophilic properties, which may be advantageous for applications where wettability or absorbency is desirable (e.g., diapers, feminine hygiene pads, etc.). Such properties have been observed in fibers containing 25% NuPlastiQ and may be provided in fibers containing more or less NuPlastiQ, within any of the ranges described herein.

[0169] Given the differences in hydrophobicity of the materials that may be included in the multicomponent or bicomponent (i.e., "bico") fiber, it is of course possible to separate the phases or components in the multicomponent or bicomponent (i.e., "bico") fiber; the sheath may be of one composition and the core may be of another composition. Other bicomponent geometries are also, of course, possible, as well as providing for differences in composition in the different fiber component geometries (e.g., segmented pie fibers, islands-in-sea fibers, etc.). In such bicomponent fibers, one or both locations (e.g., sheath vs. core, islands vs. sea, etc.) may include a starch-based polymer material, while the other location may similarly have the desired compositional characteristics (e.g., may include a higher or lower fraction of starch-based material compared to other bicomponent fiber locations, or may not include starch-based material at all).

[0170] It is particularly advantageous to be able to form bicomponent fibers in which at least one of the geometries of the bicomponent fiber (e.g., sheath, core, etc.) comprises a starch-based polymer. For example, as described herein, 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 homogeneous, regular fibers. It is even more surprising that such very high viscosity starch-based materials can be extruded through thinner geometries, such as those associated with sheath / core or other bicomponent fiber geometries. Diagrams illustrating such sheath / core bicomponent fibers formed are shown in Figures 10-17, with the starch-based material in the core and the thermoplastic material sheath (e.g., PP or PLA). In other embodiments, the locations of the materials may be reversed; for example, the starch-based polymer may be in the sheath and the thermoplastic material in the core, or the starch-based material may be present in both portions (e.g., in different ratios from the thermoplastic material in each).

[0171] Low water content, as is common in some other TPS materials that may have relatively low water content, is not achieved in NuPlastiQ materials by esterification or etherification. Such esterification or similar modifications can be costly and complicated to implement. Furthermore, NuPlastiQ materials, which are exemplary of starch-based materials usable herein, have been mechanically, physically, or chemically reacted and / or altered compared to the starting starch and glycerin materials. For example, the starch-based materials may be the product of a reactive extrusion process, e.g., under pressure, at the extrusion temperatures described herein. The finished starch-based materials contain native starch and glycerin, but have undergone chemical and / or physical changes, including changes in molecular weight relative to the starting starch material, and may not be recognized as a simple mixture. The low water content achievable in starch-based materials may be due, at least in part, to the physical or chemical transformation of the starch and plasticizer materials into a starch-based thermoplastic polymer, which does not retain water, as may be the case with native starch or other conventional thermoplastic starch materials. Additionally, NuPlastiQ materials, in common with many other thermoplastic starches, resist recrystallization or retrogradation. Conventional thermoplastic starches exhibit a tendency to "retrogradation," which occurs when they recrystallize over time from a relatively amorphous state to a more crystalline state, i.e., back to the native state of native starch powder. Most thermoplastic starches recrystallize over time because the thermoplastic starch structure is not sufficiently stabilized to limit the mobility of starch molecules, the migration of plasticizers, and evaporation over time. In contrast, NuPlastiQ does not retrogradate or recrystallize to any significant extent. Although some starch-based polymeric materials are enzymatically debranched (e.g., to increase the amylose fraction and decrease the amylopectin fraction) to reduce their molecular weight, the starch-based polymeric materials described herein are typically not enzymatically treated for debranching or other purposes, although they may exhibit a reduced (or increased) molecular weight and / or increased amylose content compared to the starting starch material.In either case, as described herein, the resulting molecular weight of the starch-based polymeric material can be relatively high.

[0172] In addition to the starch-based materials being thermoplastic, high molecular weight NuPlastiQ materials can also be solid at ambient temperatures but flow as a liquid when heat, pressure, and / or friction is applied. Advantageously, pellets of high molecular weight NuPlastiQ, when blended with a diluent thermoplastic polymer as described herein, can be used generally in the same way as any typical plastic resin pellets in standard plastic production processes, including thin fiber spinning processes (spunbond, meltblown, or yarn processes), to achieve the necessary rheological properties for such spinning.

[0173] Starch-based polymeric materials may also be strain-hardening themselves, without the addition of a strain-hardening component to achieve such properties. This apparent strain-hardening property of the NuPlastiQ starch-based materials of the present invention contrasts with the properties of other starch-based polymeric materials, which appear to exhibit strain-thinning properties that exacerbate attempts to spin them. For example, strain-hardening materials will actually increase viscosity (resistance to flow) over time, even under constant applied shear conditions, while strain-thinning materials will do the opposite (decreasing viscosity over time). The starch-based materials of the present invention may themselves exhibit such strain-hardening properties, without any need to add a separate strain-hardening additive to the formulation. This feature of strain hardening is important and valuable.

[0174] The starch-based materials of the present invention appear to exhibit strain hardening properties, which greatly aid in the ability to effectively spin such starch-based materials, and this property is one of those that appears to be important in allowing such spinning to occur even with such very high molecular weight starch-based materials.

[0175] The starch-based material can be non-toxic and is made using all edible raw materials. The resulting high molecular weight starch-based material can be water-resistant. Interestingly, Applicant observed that films containing a fraction (e.g., about 25% by weight) of starch-based material as described herein, as opposed to fibrous forms, can have relatively low surface wettability (e.g., 340 μN (34 dynes) / cm or less), similar to the hydrophobicity of many typical polyolefins (e.g., polyethylene or polypropylene). However, Applicant surprisingly observed that NuPlastiQ / PP nonwoven fabrics formed as described herein can be significantly more hydrophilic, with greater wettability and absorbency than control standard polypropylene nonwoven fabrics and fibers. Such improved wettability can be advantageous for some applications (e.g., disposable hygiene products such as diapers and feminine hygiene products).

[0176] For example, by comparison, typical polyethylene and polypropylene films often have a surface wettability rating of about 290-320 μN (29-32 dynes / cm). NuPlastiQ blends with such polyolefins in film form may exhibit similar wettability, with wettability values ​​under the dyne test (e.g., measured according to DIN 53394 / ISO 8296) of less than 400 μN (40 dynes / cm), less than 380 μN (38 dynes / cm), less than 360 μN (36 dynes / cm), or less than 340 μN (34 dynes / cm). However, as noted above, applicants may not fully understand why the fiber morphology of such blends described herein appears to be much more hydrophilic (e.g., surface wettability greater than 340 μN (34 dynes) / cm, greater than 360 μN (36 dynes) / cm, greater than 380 μN (38 dynes) / cm, or greater than 400 μN (40 dynes) / cm).

[0177] Like paper, NuPlastiQ does not generally undergo biodegradation under typical storage conditions, even in relatively humid conditions, due to the absence of anaerobic digesters, industrial compost, or other conditions of similar waste environments that contain the specific necessary microorganisms. Of course, when such conditions exist, not only does NuPlastiQ biodegrade, but a significant portion of other non-biodegradable plastic materials (e.g., polypropylene) blended with it have surprisingly been shown to biodegrade as well. Extensive evidence of this is set forth in Applicant's other applications, which have already been incorporated herein by reference.

[0178] The starch-based material can be substantially amorphous. For example, raw starch powder typically has about 50% crystalline structure. Many thermoplastic starch materials also have relatively high crystallinity. For example, the starch-based material used as described herein can have a 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 crystallinity can be used, including, but not limited to, FTIR analysis, X-ray diffraction, and symmetric reflection and transmission techniques. Various suitable testing methods will be apparent to those skilled in the art.

[0179] As described herein, blending a starch-based material with a plastic material (e.g., a thermoplastic material with a higher melt flow index selected to dilute and further plasticize the starch-based material) can result in not only the starch-based material being rapidly biodegradable, but also the non-biodegradable thermoplastic material contained within the blend actually becoming significantly more rapidly biodegradable as well (even if the high melt flow index thermoplastic material alone is not significantly otherwise biodegradable). Naturally, such a result has not occurred in previously reported blends. Such a result has been documented, at least when blended with NuPlastiQ. It is believed that highly intimate blending of the starch-based component into other plastic materials, as well as other factors, may enable this to occur.

[0180] Without being bound by any particular theory, it is believed that starch-based materials (e.g., particularly in the case of NuPlastiQ) may interfere with the moisture-wicking barrier properties of polyethylene or other non-biodegradable plastic materials by intimately blending the two together and allowing microorganisms to degrade the arrangement and bonds of the other non-biodegradable plastic molecules in the blend along with the highly intimately dispersed starch-based material. The highly intimate dispersion of very small particles or domains of the starch-based component may also be important in any such mechanism, since the starch particles or domains are so well dispersed that microorganisms readily encounter other polymeric materials. Because of such dispersion, after consuming a given starch-based particle, microorganisms may continue "munching" on the polymeric material until they encounter the next adjacent starch-based particle (which may be more easily digested).

[0181] Indeed, PiFM analysis of such blends indicates that the typical separate, relatively pure polyolefin "sea" surrounding the starch domain "islands" does not form, but rather that starch material is present within the polyolefin "sea," and polyolefin is present within the starch "islands," thus preventing the formation of the separate, relatively pure domains present in conventional starch / polyolefin blends. Further details regarding such analysis can be found in the prosecution history of Applicant's patent application Ser. No. 15 / 481,823 (now U.S. Pat. No. 10,919,203), which is incorporated herein by reference. Blends of NuPlastiQ with another thermoplastic material, in contrast to conventional starch or starch-based materials, exhibit a substantial lack of pure "islands-in-the-sea" characteristics. This does not mean that the blend cannot exhibit some heterogeneous morphology characteristics, but rather that there will be starch materials within any polyolefin "sea" and polyolefin within starch "islands," thus eliminating the distinct, relatively pure domains present in conventional starch / polyolefin blends. Such morphologies are also believed to occur in other plastics (e.g., polyester, polystyrene, and others) when blended with NuPlastiQ starch-based polymer materials. Theoretically, the long polymer chains of polypropylene or other non-biodegradable plastic materials, when homogeneously blended with the currently contemplated starch-based materials, may be more easily cleaved by bacterial and microbially active environments. Microorganisms naturally present in waste environments (e.g., anaerobic digesters or industrial composting) can then consume the cleaved molecules, converting them into naturally occurring mineralized components (such as CO2, CH4, and HO). Even if such an article may be placed in an undesirable environment (e.g., cluttered conditions), biodegradation of the non-starch components can be achieved much faster with NuPlastiQ present in the blend.At least in the case of NuPlastiQ, and in tests conducted to date in film form, NuPlastiQ does not appear to promote macrostructural fragmentation into small pieces, but the articles formed tend to biodegrade while appearing to remain substantially intact for most such processes. This biodegradation effect is further enhanced and more consistently achieved when the starch-based component is closely and homogeneously dispersed with very small domain sizes, as described, for example, in applicant's U.S. patent application Ser. Nos. 16 / 925,747 (21132.30.1) and 16 / 925,705 (21132.27.1.1), each of which is incorporated herein by reference in its entirety. While some prior art references may describe blend morphologies in which a starch or thermoplastic starch phase is in the discontinuous (or continuous) phase and a 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 may not be structured in that way, but comprise a starch-based polymeric material in any polyolefin or other plastic resin phase, as well as a polyolefin or other plastic resin material in a starch-based polymeric material phase.

[0182] Biodegradable plastics are converted into naturally occurring elements or compounds such as carbon dioxide, methane, water, inorganic compounds, or biomass through microbial assimilation (e.g., microbial enzymatic action on plastic molecules), a process sometimes called "mineralization."

[0183] Plastics made from petrochemical feedstocks begin life as monomers (e.g., single small molecules that can chemically react with other small molecules). When the monomers link together, they become polymers ("many parts"), which may be known as plastics. Before linking, many monomers are readily biodegradable, but after they are linked together through polymerization, the molecules become so large that they are linked in configurations and bonds that microbial assimilation is impractical in most cases within a reasonable timeframe for many materials, including, particularly, polyethylene and polypropylene. However, the high molecular weight NuPlastiQ starch-based compositions described in this invention may confer enhanced biodegradability to other non-plant-based polymers.

[0184] Polyolefins, such as robust forms of polyethylene and polypropylene, are highly crystalline and are made by converting monomer molecules (whether small building block molecules derived from petroleum, ethanol, or other plant sources) into long-chain, high-polymers. The bonds created when connecting the monomers to form long polymer chains are strong and difficult to break. Thin fibers and articles formed from such polymer materials (e.g., polyethylene and polypropylene) are not biodegradable as defined herein and have considerable strength. Of course, there are several polymers available that can be consumed through microbial assimilation and made spinnable under certain conditions (e.g., PLA can be industrially compostable under ASTM D-5338 or ASTM D-6400, and some PLA can be spun into fibers), but such materials are significantly more expensive than polyethylene or polypropylene. Even when a given article is formed from a blend of a conventional non-biodegradable plastic material with a conventional thermoplastic starch "TPS" material described as suitable for spinning (e.g., as described in various Kimberly-Clark and P&G references), the non-biodegradable plastic component in such a formulation does not acquire significant biodegradable properties as a result of such blending. For example, only the starch portion or other recognized compostable resin component (e.g., PLA) of the blend is available for microbial assimilation, and access to such components is not blocked or occluded by a non-biodegradable matrix that may prevent access to portions of some such components (e.g., as may occur when the blend is in a form that includes a continuous non-biodegradable phase encapsulating a biodegradable or compostable phase).

[0185] One or more starch-based materials can be present in the mixture of materials in any desired proportion. For example, the starch-based material can be present in an amount of at least 0.5%, at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 10%, at least 15%, at least 20%, up to 99%, up to 95%, up to 90%, up to 80%, up to 70%, up to 60%, up to 50%, between 2% and 60%, between 5% and 40%, between 10% and 40%, between 20% and 35%, or between 20% and 30% by weight of the mixture of materials. Optionally, 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 for inclusion in a blend may include molecular weight distribution, isotacticity (e.g., isotactic polypropylene), long chain branching, copolymers incorporating polypropylene isomers, etc.

[0186] In at least some of the following examples, at least two thermoplastic materials are included, each exhibiting a different melt flow index value. In one embodiment, at least some threshold amount of high molecular weight starch-based material is included, but it is possible that the article may include another starch-based material that may 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 differ from the primary starch-based material. That is, in one embodiment, the lower molecular weight starch-based material may not be intentionally added. Of course, it will be understood that starch-based materials exhibit a distribution of molecular weights, and even high molecular weight starch-based materials themselves may contain some fraction of lower molecular weight molecules.

[0187] The thermoplastic diluent material with which the starch-based material is blended can be present in the mixture of materials in an amount of at least 1%, at least 2%, at least 3%, at least 4%, 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%, up to 99%, up to 95%, up to 90%, up to 85%, up to 80%, up to 75%, more typically 10% to 90%, 20% to 85%, 40% to 80%, or 60% to 80% by weight of the mixture of materials. Two or more such thermoplastic materials (i.e., combinations of such thermoplastic resins, each having different melt flow index properties) can be included in the blend.

[0188] By way of example, a blend (e.g., useful in a spunbond process) may contain a significant fraction of at least one thermoplastic material selected for its 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 may be present in the blend in an amount of at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, such as 40 to 60% of the blend, along with an additional second thermoplastic material having a significantly lower melt flow index (e.g., 10 to 50, such as 35). Such a second thermoplastic material may be present in an amount of at least 5%, at least 10%, or at least 15% by weight, such as 10% to 30%, or 15% to 25% of the blend. Examples illustrate such blends, including, for example, 50% polypropylene with an MFI of 100 or 500, 21% polypropylene with an MFI of 35, 4% maleic anhydride-modified polypropylene compatibilizer, and 25% high molecular weight starch-based polymer. Some examples collectively contain 60-80% by weight of two different diluents: high melt flow index thermoplastic polymers (e.g., PP).

[0189] Blends formulated for meltblowing may have similar fractions of thermoplastic materials selected for their melt flow index, but the selected melt flow index value may be higher than for spunbond due to the more severe processing associated with the meltblowing process. For example, the melt flow index of one of the thermoplastic materials for meltblowing may be 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).

[0190] Blends formulated for yarn processing may have similar fractions of thermoplastic materials selected for their melt flow index, but the selected melt flow index value may be lower than for spunbond due to the less stringent processing and strength requirements associated with the yarn process. For example, the melt flow index of one of the thermoplastic materials for the yarn process may be 50-200 (e.g., 50-150, 75-125, such as about 100 g / 10 min at 230°C under a 2.16 kg load). The same masterbatch material (e.g., containing a 35 MFI diluent thermoplastic material) may be used for spunbond, meltblown, or yarn, the primary difference being the MFI of the diluent thermoplastic material with which the masterbatch material is blended. In either case, the overall principle is to provide a resulting formulation with a BPI shear viscosity (as described below) low enough to pass through a given fiber spinning system (spunbond, meltblown, or yarn) while avoiding the development of melt flow instabilities in those portions of the process that exhibit the highest shear (e.g., the spinneret). While the use of the same masterbatch formulation, e.g., the ability to use a single masterbatch for any of such processes, can be advantageous, it will be understood that any of a variety of masterbatches can be provided, for example, where a starch-based polymeric material is blended with any desired MFI diluent thermoplastic material (e.g., 35 MFI, 100 MFI, or other) in a masterbatch.

[0191] A compatibilizer can optionally be present in the material mixture, typically provided as a component of a masterbatch, but alternatively 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 polybutene, maleic anhydride-grafted polyolefin copolymer, combinations of any of the above, 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 version of one of the thermoplastic diluent materials (e.g., maleic anhydride grafted polypropylene when the plastic material is polypropylene) or a copolymer (e.g., a block copolymer) in which one of the blocks is the same monomer as the thermoplastic material (e.g., a styrene copolymer when the thermoplastic material is polystyrene or ABS). The selection of a particular compatibilizer often depends on the identity of the thermoplastic diluent resin materials included in the blend, and the compatibilizer, if any, can be selected to provide good compatibility results between the high molecular weight starch-based material and any particular thermoplastic diluent material being used.

[0192] If present, the final blend may contain 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%, 50 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, 25 wt% or less, 20 wt% or less, 15 wt% or less, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 0.5 wt% to 12 wt%, 2 wt% to 7 wt%, or 4 wt% to 6 wt% of compatibilizer. In some embodiments, such a compatibilizer will not be required. The masterbatch may contain double or other multipliers of such amounts depending on the blend ratio of the masterbatch to the thermoplastic diluent material with which it is blended. For example, if it may be desirable for the final blend to contain 4% compatibilizer, the masterbatch may contain 8% compatibilizer, which is blended down at a 1:1 ratio.

[0193] One or more additional "active" additives known to be useful in the plastics industry may be included in the mixture of materials in an amount of at least 0.5%, at least 1%, at least 1.5%, at least 2%, at least 2.5%, at least 3%, at least 4%, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 0.2% to 12%, 1% to 10%, 0.5% to 4%, or 2% to 6% by weight of the mixture.

[0194] For example, spunbonding, meltblowing, yarn or other spinning processes for forming articles may involve heating a mixture of materials. The viscosity of the starch-based material of the present invention has been observed to be particularly temperature-sensitive. For example, high molecular weight starch-based materials exhibit viscosity characteristics that are approximately one order of magnitude greater than those required for spinning conventional starch materials, but the applicant has found that this viscosity can be reduced through a combination of actions, including, but not limited to, selecting appropriate process temperatures at which extrusion and spinning should occur.

[0195] In embodiments, the mixture of materials can be heated to a temperature above the melting point of the polypropylene or other diluent thermoplastic polymer of the blend. For example, many polypropylenes can melt at about 160°C or above, while many polyethylenes can melt at about 110°C or above. 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, 250°C or less, 230°C or less, 225°C or less, 220°C or less, 210°C or less, 205°C or less, 200°C or less, 195°C or less, 180°C to 210°C, 185°C to 205°C, or 185°C to 200°C (e.g., 190°C or 195°C). A typical polypropylene process can heat up to about 230°C, which may be too high for the compositions of the present invention, where it is desirable to minimize thermally induced degradation of the starch-based polymeric material. Thus, in at least some embodiments, the temperature of the spinning system need not exceed 210°C, or even 200°C. While some might expect such lower temperatures to make spinning more difficult due to the decrease in viscosity with temperature, applicants have found the feasibility of spinning and even the benefit of minimizing degradation of the starch-based polymeric material at such lower temperatures. As described herein, applicants have also found that such temperatures are sufficient to provide the necessary viscosity and other rheological properties to enable fiber spinning.

[0196] Heating of such materials can be carried out, for example, in a multi-stage extruder in which progressive stages are heated to higher temperatures than the previous stage, with each stage of the extruder heating the mixture of materials to a given temperature, as will be apparent to those skilled in the art. In one embodiment, the temperature of the first stage of such an extruder for the blend at which heating begins can be in the same range as the temperature of the starch-based material (e.g., NuPlastiQ) in the reactive extrusion process from which it was produced.

[0197] As noted above, it may be important to ensure that the processing temperature at which fiber formation occurs is not so high as to exceed the decomposition temperature of the starch-based polymeric material. As noted above, heating may be used to reduce the viscosity of the formulation, and the starch-based materials employed herein exhibit a rapid decrease in viscosity as the temperature increases, which allows the composition to be spun into fibers at commercial line speeds without entering melt flow instabilities, and the associated high shear rates (e.g., typically 1000 sec-1 through the spinneret). -1 This will significantly help ensure that

[0198] For example, shear stress is equal to melt (shear) viscosity times shear rate, and the applied shear stress is used to force the fiber through, for example, 1000 sec -1 It is important to maintain the formulation's critical shear stress below the critical shear stress for spinning at typical commercial spinneret shear rates. Typical resins suitable for spinning (e.g., polypropylene) exhibit a critical shear stress value of approximately 100 kPa, above which severe problems occur and usable fiber formation becomes impossible. Some resins exhibit more favorable critical shear stress values ​​up to approximately 300 kPa, providing additional latitude in operating the system to ensure that the critical shear stress is not exceeded. The starch-based polymeric materials employed herein exhibit critical shear stress values ​​higher than the typical 100 kPa limit, possibly as high as 300-400 kPa, providing additional latitude in operating the system, which may allow for higher line speeds while still maintaining the system below the applicable critical shear stress. Even when blended into a masterbatch with a diluent material having a relatively low critical shear stress, the critical shear stress of the masterbatch containing the starch-based polymeric material can still be 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.

[0199] In some cases, the mixture of materials including the thermoplastic diluent material and the starch-based material can be heated in one or more chambers of the 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 any desired speed. In one embodiment, the system can be configured as a single-screw extruder.

[0200] Thin fibers are spun using a mixture of materials, for example, through a spunbond, meltblown, or yarn process. Depending on the process and desired use, the formed fibers can be produced and wound for use as intermediate materials used in the manufacture of any of a wide variety of products. Depending on the process and desired use, the process can also convert the formed thin fibers into a nonwoven web of such fibers, which can be bonded together, for example, through a thermal calender or otherwise, to produce a nonwoven fabric. There are numerous other possible bonding mechanisms that can be used, as will be apparent to those skilled in the art (e.g., including, but not limited to, needle punching, hydroentangling, through-air bonding, chemical adhesive bonding, etc.). Such processes can be used to bond fibers of individual plies or layers together, or can also be used to bond separate plies or layers together, for example, when forming multi-ply or multi-layer composite structures that may incorporate different nonwoven materials in different layers or films. Figures 21-23, described below, schematically illustrate exemplary spunbond, meltblown, and yarn processes.

[0201] When nonwoven fabrics are formed, the nonwoven webs can be constructed in a single layer or multiple layers. The weight (e.g., basis weight) of such nonwoven layers or webs can be within any desired range. Exemplary weights are often 10 g / m². 2 (gsm) ~800gsm, 10g / m 2 (gsm) ~ 500gsm, 10g / m 2 (gsm) ~300gsm, 10g / m 2 (gsm) to 150 gsm, or 10 to 100 gsm. Lightweight nonwovens can be particularly useful, for example, at 10 to 20 gsm.

[0202] When subjected to biodegradation testing (e.g., under any applicable ASTM standard, such as ASTM D-5511, ASTM D-5526, ASTM D-5338, or ASTM D-6691), the articles described herein may exhibit significant biodegradation. Under such testing, and within a given period of time (e.g., 180 days, 365 days (1 year), 2 years, 3 years, 4 years, or 5 years), the articles may exhibit substantial biodegradation of their total polymer content, typically including non-biodegradable polymer components. Articles made from the compositions of the present invention may exhibit greater biodegradation than their high molecular weight starch-based polymer content, as a result of the thermoplastic material also biodegrading. Such results are novel in that all prior art blends known to applicant containing non-biodegradable plastic materials (e.g., polypropylene) and starch-based materials always exhibit biodegradation values ​​equal to or less than (and usually lower than) the starch-based material content of the blended materials. For example, materials such as those described in Kimberley-Clark or P&G patent literature containing polypropylene do not exhibit biodegradation of the polypropylene portion. The same is certainly true, as such references describe starch blends containing other polymers recognized as not biodegradable. Of course, some such references describe the use of recognized biodegradable or compostable polymers (e.g., PLA) to improve the biodegradability of articles. The present invention addresses biodegradability in an entirely different manner, making polypropylene and similar "inert" polymers susceptible to microbial assimilation. Of course, it is also within the scope of the present invention to incorporate or otherwise use PLA, PBAT, or other more "green" polymers in blends, for example, as thermoplastic materials having specific, selected melt flow index values. The biodegradation of polypropylenes such as those contained in the current blends has been confirmed by various third-party tests using industry-recognized respirometry-based biodegradation tests (e.g., ASTM D-5338, ASTM D-5526, ASTM D-5511, ASTM D-6991).

[0203] In particular, when the article is subjected to tests simulating biodegradation under anaerobic digester or industrial composting conditions for 180 days, 365 days (1 year), 2 years, 3 years, or 5 years, biodegradation may be greater than the weight percent of the starch-based material in the article, and other unrecognized biodegradable materials are not included therein. In other words, the inclusion of the described starch-based material may result in at least some biodegradation of other thermoplastic materials (which may not be significantly biodegradable by themselves in the absence of the starch-based material).

[0204] When subjected to biodegradation testing, articles made from the compositions of the present invention having a certain amount of starch-based material and other thermoplastic materials, as described herein, can exhibit excellent biodegradation. 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., "other" plastic material, such as polypropylene, another polyolefin, or other plastic that is itself non-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 under any of ASTM D-5338, ASTM D-5526, ASTM D-5511, and ASTM D-6991. Such biodegradation is particularly significant and advantageous.

[0205] With increasing time, the amount of biodegradation can become so great that, in at least some embodiments, substantially the entire article biodegrades, e.g., at least about 85%, at least about 90%, at least about 95%, or with biodegradation at least equal to the degradation of a positive control (e.g., cellulose) under a given test standard. Such a result may be achieved within 180 days, or 365 days (1 year), or within 2 years, 3 years, 5 years, or other time periods. Biodegradation can be considered substantially complete when the amount of biodegradation in the article is at least 90% of that achieved in a cellulose positive control tested under the same conditions for the same period of time.

[0206] FIG. 21 schematically illustrates an exemplary spunbond process 100. Those skilled in the art will recognize that various components of the system may vary and that the illustrated system and process 100 are merely exemplary. As shown, the polymer blend may be fed to an extruder 104 through one or more hoppers 102. As described herein, various components of the formulation (e.g., the starch-based polymeric material and the thermoplastic diluent-plasticized polymer (e.g., polypropylene having a desired MFI value) may be provided to a single hopper, through different hoppers, or the like. As described herein, the starch-based polymeric material may be provided as a masterbatch (e.g., available from the applicant) in which the starch-based polymeric material is already pre-blended with at least one thermoplastic diluent material and, optionally, a compatibilizer. Such a masterbatch may be further blended with additional thermoplastic diluent polymer in the extruder 104.

[0207] The homogeneously blended composition for spunbonding may be passed through a filter 106 to remove any undesirable contaminants. At 108, a pump is provided that conveys the heated composition (e.g., 195°C) to a spinneret 110 where fibers are formed due to the specific rheological properties of the compositions described herein. At 112, the quenching portion of the system is shown. At 114, the fibers are attenuated for deposition onto a substrate (e.g., a conveyor belt) 116 to form a desired nonwoven fabric from the as-spun fibers from the spinneret, quenching portion, and attenuation portion of the system. The forming section associated with the substrate 116 may include one or more guide rollers 118 and edge guides 120 to assist in forming a nonwoven web from the spun fibers. After formation, the nonwoven web may pass through a compression roller 122 and a calender roller 124, after which the formed spunbond nonwoven web is wound onto a winder 126.

[0208] As described above and in the examples, formulations used in spunbond processes such as process 100 include a starch-based polymeric material (e.g., at any weight fraction described herein, such as 1% to 30%, 5% to 30%, 2% to 5%, 5% to 10%, 10% to 20%, or 20% to 30% by weight of the formulation blend). The thermoplastic diluent material is specifically selected to ensure that the shear viscosity of the resulting formulation is sufficiently low so that it can be passed through system 100, particularly the high-shear spinneret fiber-forming portion of the process, without the onset of melt flow instability. As described above and in the examples, the thermoplastic diluent can include polypropylenes with different MFI values, such as an MFI value of 35, an MFI value of 100, and an MFI value of 500. In one embodiment, the masterbatch may include 50% starch-based polymeric material, 8% compatibilizer, and 42% 35 MFI polypropylene, while other polypropylenes (e.g., 100 MFI and 500 MFI) are added separately and blended with the masterbatch in extruder 104. Such an example is merely illustrative and illustrates one possible formulation suitable for use in such spunbond systems and processes. As a further example, the formulation may have a BPI (described below) of less than 300 Pa·s and be processed at 2000 m / min through a 0.35 mm die diameter at 195°C to produce fibers having a diameter of approximately 20 μm. The tenacity of such fibers may be at least 1.4 gpd. Multi-structured fibers (sheath / core or other geometries described herein) are, of course, possible.

[0209] FIG. 22 schematically illustrates an exemplary meltblowing process 200. Those skilled in the art will recognize that various components of the system may vary and that the illustrated system and process 200 are merely exemplary. As shown, the polymer blend may be fed to an extruder 204 through one or more hoppers 202. As described herein, the various components of the formulation (e.g., the starch-based polymeric material and the thermoplastic diluent-plasticized polymer (e.g., polypropylene having a desired MFI value) may be provided to a single hopper, through different hoppers, or the like. As described herein, the starch-based polymeric material may be provided as a masterbatch (e.g., available from the applicant) in which the starch-based polymeric material is already pre-blended with at least one thermoplastic diluent material and, optionally, a compatibilizer. Such a masterbatch may be further blended with additional thermoplastic diluent polymer in the extruder 204.

[0210] To produce meltblown fibers, the homogeneously blended composition may be passed through a gear pump 206, which conveys the heated composition (e.g., 205°C) to a die body 210 where fibers are formed due to the specific rheological properties of the composition described herein. At 208, heated air (e.g., higher than the polymer composition, e.g., 220°C to 250°C, such as 230°C) melts the polymer through a die in the die body 210, forming thin fibers that may be passed through cooling air (not labeled), and the fibers may be collected on a collector 212 and wound on a winder 214.

[0211] As explained herein, such meltblowing processes typically produce smaller fibers than those formed in spunbond processes (e.g., 2-4 μm vs. 15-30 μm), and the formulations are typically subjected to more extreme conditions that require higher melt flow index values ​​from the thermoplastic diluent materials used in such meltblowing processes. Meltblown fibers can be incorporated directly into nonwoven structures, typically with spunbonded layers (SMS), hybrid structures, etc., or wound as a separate layer.

[0212] As described above and in the examples, the formulation used in a meltblowing process such as process 200 includes a starch-based polymer material (e.g., at any weight fraction described herein, such as 1% to 30%, 5% to 30%, 2% to 5%, 5% to 10%, 10% to 20%, or 20% to 30% by weight of the formulation blend). The thermoplastic diluent material is specifically selected to ensure that the shear viscosity of the resulting formulation is sufficiently low so that it can pass through system 200, and particularly the majority of the process, and be drawn into thin fibers by hot air without developing melt flow instabilities. As described above and in the examples, the thermoplastic diluent can include polypropylene with different MFI values, such as an MFI value of 35 and an MFI value of 1550. In one embodiment, the masterbatch may include 50% starch-based polymeric material, 8% compatibilizer, and 42% 35 MFI polypropylene, while the other polypropylene (e.g., 1550 MFI) is added separately and blended (e.g., 1:1 or other desired ratio) with the masterbatch in extruder 204. Such an example is merely illustrative and illustrates one possible formulation suitable for use in such meltblowing systems and processes. As a further example, the formulation may have a BPI (described below) of less than 200 Pa·s and, at 205°C, may produce fibers with diameters of 2-4 μm through a 0.4 mm die diameter. Multi-structured fibers (sheath / core or other geometries described herein) are, of course, possible.

[0213] FIG. 23 schematically illustrates an exemplary yarn process 300. Those skilled in the art will recognize that various components of the system may vary and that the illustrated system and process 300 are merely exemplary. As in other processes, the polymer blend may be fed to 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-plasticized polymer (e.g., polypropylene having a desired MFI value) may be provided to a single hopper, through different hoppers, etc. As described herein, the starch-based polymeric material may be provided as a masterbatch (e.g., available from the applicant) in which the starch-based polymeric material is already pre-blended with at least one thermoplastic diluent material, and optionally a compatibilizer. Such a masterbatch may be further blended with additional thermoplastic diluent polymer in the extruder 302.

[0214] The homogeneously blended composition for yarn formation can be delivered to a pump 304, which delivers the heated composition (e.g., 205°C) to a filter pack spinneret 306 where fibers are formed, due to the specifically provided rheological properties of the composition described herein. At 308, the inlet air quench duct portion of the system is shown. At 310, the spin duct, and at 312, the spin finish are shown. In such a yarn process, the fibers exiting the spin duct 310 (e.g., at 312) can be relatively thick, e.g., 60 μm, and can be formed at a relatively slow line speed (e.g., 650 m / min). At 314, a godet roller is shown, and a take-up roller is shown at 316. In such a yarn process, this initial portion (the left portion of the process in FIG. 23) results in the formation of a relatively thick yarn fiber, and the as-formed fiber can be drawn downward to a smaller diameter either immediately after initial fiber formation or after, as shown in the right portion of the process seen in FIG. 23.

[0215] In either case, as shown in FIG. 23 , the relatively thick yarn from take-up roller 316 can be transferred to the drawing stage of the yarn process on a supply spool (also labeled 316 because this can simply be one of the packed take-up rollers). The relatively thick yarn is conveyed across draw roller 320 and through heater 318 (e.g., at 75°C to 130°C, such as 100°C), where the yarn is drawn downward 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, a heating tube (not shown) and a texturing device 324 can be present. By way of example, if a polyamide material is used, such a texturing step can be present. If the thermoplastic diluent material employed is polypropylene or other similar material, texturing may not be provided. At 326, the finished yarn is wound onto a roller. As an example, the finished yarn at 326 may have a diameter of about 20 μm and be produced at a line speed of about 1800 m / min (compared to an as-spun yarn at 60 μm, 650 m / min, which is then drawn). The fiber bundle may be relaxed between the drawing godet and the winder by adjusting the speed differential and fiber temperature.

[0216] As described above and in the examples, the formulations used in yarn processes such as process 300 include a starch-based polymer material (e.g., at any weight fraction described herein, such as 1% to 30%, 5% to 30%, 2% to 5%, 5% to 10%, 10% to 20%, or 20% to 30% by weight of the formulation blend). The thermoplastic diluent material is specifically selected to ensure that the shear viscosity of the resulting formulation is sufficiently low so that it can be passed through system 300, and particularly the spinneret fiber-forming portion of the process, without the onset of melt flow instability. As described above and in the examples, the thermoplastic diluent can include polypropylenes with different MFI values, such as an MFI value of 35 and an MFI value of 100. In one embodiment, the masterbatch may include 50% starch-based polymeric material, 8% compatibilizer, and 42% 35 MFI polypropylene, while the other 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 an example is merely illustrative and illustrates one possible formulation suitable for use in such a yarn system and process. As a further example, the formulation may have a BPI (described below) of less than 600 Pa·s or less than 500 Pa·s and may be processed at 205°C through a 0.35 mm die diameter at 650 m / min in the spinning portion of the process and 1800 m / min in the drawing portion of the process to produce a fiber having a diameter of approximately 20 μm. The tenacity of such a fiber may be at least 2.5 gpd. Multi-structured fibers (sheath / core or other geometries described herein) are, of course, possible.

[0217] IV. Working Examples Example 1 Exemplary formulations with various component ranges are shown in Table 2 below, along with some exemplary rheological properties for meltblown, spunbond, and yarn. [Table 2]

[0218] For this application, various starch-based polymeric materials were rheologically evaluated, and one particular starch-based polymeric material was selected for spinning based on the measured properties. The base starch or majority starch in the evaluated materials was corn starch (Corn 1 or Corn 2). Corn 1 is an unmodified starch from natural yellow dent corn. Corn 2 is a modified corn starch. In the formulations used in the spinning examples described herein, the starch-based polymeric material was formed from only a single starch (Corn 2) rather than a mixture of two different starches (Corn 1 or Corn 2 + Potato). The formed starch-based material exhibited a very high weight-average molecular weight, for example, 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) may actually be less than the molecular weight of the resulting starch-based polymeric material after reactive extrusion with a plasticizer, as determined via size exclusion chromatography. In other words, in some cases, the reactive extrusion process may actually result in an increase in average molecular weight, e.g., accompanied by a decrease in polydispersity. As an example, analysis for Corn2 (a modified corn starch) shows the following molecular weight characteristics: [Table 3]

[0219] The polydispersities (Mw / Mn) of Runs 1 and 2 for this modified corn starch material were 2.55 and 3.22, respectively. An exemplary starch-based polymer material formed from the corn starch in Table 3A and a plasticizer (e.g., glycerin) contained the following molecular weight characteristics, as shown in Table 3B. The starch-based polymer material formed had a polydispersity (Mw / Mn) of 1.99. The reported Mz values ​​refer to the "third moment" molecular weight, with more weighting for higher molecular weights. [Table 4]

[0220] In conducting the rheological studies, it was determined that 190°C was a good temperature for the study, high enough to melt the polypropylene and other components of the formulation, but low enough to comfortably manage the stability of the starch-based polymer material (i.e., prevent degradation). Limited additional testing was conducted at additional temperatures (e.g., 180°C to 205°C).

[0221] Cogswell extensional viscosity measurements were performed on three samples. Temperature sweep measurements were also performed on two other samples. Viscosity versus shear rate for Sample 984 is shown in Figure 1. Sample 984 was formed from Corn 1 as the base corn starch and 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 Figure 1 and other figures (e.g., Figure 7A), high molecular weight starch-based polymer materials have very high viscosities. As noted above, the starch-based polymer material used in the spinning example was formed from Corn 2 and exhibited a somewhat lower viscosity, but the viscosity profile is still at least an order of magnitude higher than that of starch-based materials previously adapted for spun thin fibers. Such a large difference is due (at least in part) to the very high molecular weight of the starch-based materials of the present invention. For example, referring to Figure 1, the viscosity of the starch-based materials at 10 sec -1 At shear rates of 200 s, sample 984 of the polymeric starch-based material exhibits a melt or shear viscosity of over 4,000 Pa·s (e.g., at 190°C). Although such low shear viscosities are quite high, the material exhibits a melt or shear viscosity of over 4,000 Pa·s at 200 s -1 At a shear rate of 1000 sec, the shear viscosity decreases to about 600-700 Pa·s. -1 At a shear rate of 1000 s, the shear viscosity decreased to about 200-300 Pa s (similarly at 190 °C). This is a significant decrease in viscosity, but at 1000 s-1 (at 190°C), still higher than the desired targets of 125 or less, 95 or less, or 50-65 Pa·s or less.

[0222] From testing the various formulations prepared, it was observed that the rheological behavior of the starch-based materials was dominated by the base corn starch, with Corn 1 having a significantly higher viscosity than Corn 2. That is, in both cases, the weight-average molecular weight of the starch-based materials was very high, e.g., greater than 5 million. The starch-based polymer materials prepared from both base corn starch materials exhibited similar shear viscosities at low shear compared to 1 MI (melt index) LLDPE (see Figure 2), but also exhibited higher shear sensitivity. While the flow curves were smooth and essentially parallel at high shear rates (approximately a 3- to 5-fold difference between the two), the shear viscosities increased at approximately 100 sec. -1 It was also observed that the high molecular weight starch-based materials of the present invention also exhibited a nonlinear "tail-up" behavior at shear rates below 100°C. Such significant nonlinear tail-up (where the shear viscosity increases more rapidly than the already exponential increase associated with the linear relationship on the logarithmic scale shown in Figures 1-2) is unusual and likely inherent to the high molecular weight starch-based materials of the present invention.

[0223] Figure 2 shows the flow curves for both starch-based materials formed from Corn 1 corn starch and Corn 2 corn starch, as well as a comparison curve for 1MI PE (1MI LLDPE). As can be seen in Figure 2, the shear viscosity of the starch-based polymer material formed from Corn 2 is significantly lower (e.g., about 3-5 times lower) than the shear viscosity of other similar materials made from Corn 1. As shown in Figure 2, for example, the shear viscosity of the material formed from Corn 2 is approximately 10 sec. -1 Approximately 2,000 to 3,000 Pa·s, 200 seconds -1 Approximately 300 to 400 Pa·s and 1000 sec -1 As mentioned above, the shear viscosity of the material formed from Corn1 is approximately 100 Pa·s at 10 sec -1Approximately 6,000 Pa·s, 200 sec -1 Approximately 1000 Pa·s at 1000 sec -1 The temperature is approximately 400 Pa·s (all measurements at 190°C).

[0224] FIG. 3 illustrates additional flow curves for other exemplary starch-based materials formed from one or more starches and plasticizers in the ratios described herein. These curves include flow curves for various examples formed from a single starch or a combination of different starches. The flow curves illustrate how the addition of potato starch to the starch blend from which the starch-based polymeric material is formed decreases the resulting viscosity characteristics as the starch content increases. Also shown are curves for various examples in which Corn 2 was the base starch, illustrating the different flow curves for various amounts and / or types of potato starch inclusion in the starch mixture from which the starch-based material was formed. In FIG. 3, Sample 985 was formed from corn starch C1, Sample 937 was formed from corn starch C2, while the other samples were formed from blends of corn and potato starches. The choice of starch material used in forming the starch-based material can significantly affect the resulting rheological properties.

[0225] Referring to Figure 4, the high viscosity samples allow for exploration of the melt flow instability characteristics of high molecular weight starch-based materials. Note the sharp break or inflection point in the flow curve above 300 kPa, where the break is typical of land fracture (i.e., indicating melt flow instability and a critical shear stress threshold). Such very high critical shear stress values ​​are also advantageous and help enable the spinning of compositions of the present invention containing a substantial fraction of starch-based polymeric materials at commercial line speeds. For example, by comparison, polypropylene, which is widely used for spinning thin fibers, has a critical shear stress of only about 100 kPa. This property of the starch-based materials of the present invention allows for the deferral or delay of the onset of melt flow instability as more starch-based material is included in the formulation being spun. Such properties also allow the addition of fractions (e.g., even small fractions) of the starch-based materials of the present invention as additives to conventional polypropylene or other spinning formulations that exhibit relatively low critical shear stress values ​​(e.g., of about 100 kPa) to effectively increase the critical shear stress of such formulations, such as allowing for faster line speeds, which is another particular advantage provided by the presently disclosed starch-based materials.

[0226] For example, one embodiment of the present invention may therefore be directed to the use of such starch-based materials to increase the critical shear stress of a given spinning formulation by adding such materials in a desired amount. The amount of starch-based material added may be within any desired range and need not be particularly high to delay the onset of melt flow instability for the composition. By way of example, the amount of starch-based polymer added as a critical shear stress-raising agent may be any of the values ​​disclosed herein. In one embodiment, the addition may be relatively low, e.g., less than 20%, less than 15%, less than 10%, less than 5%, etc.

[0227] As shown in the figure, the flow curve of the formed starch-based material is -1Processing in spunbond or other fiber spinning systems (e.g., extruders, piping, die manifolds, etc.) typically occurs over a shear rate of 10 to 500 sec -1 200 sec -1 The shear viscosity at a shear rate of 200 sec is representative to a significant extent of the viscosity in such processing environments. A BiologiQ Processing Index (BPI), based on the viscosity of such ingredients used in a formulation, is used under such conditions (e.g., 200 sec), for use as a benchmark when evaluating various ingredients and resulting formulations. -1 BPI can be calculated or measured at 190°C using a 1 mm die with L / D=30. BPI can be a good process control tool. Finally, since the flow curves of various starch-based materials are generally parallel to each other, it also provides information about the die pressure up to the critical shear stress (e.g., τ≧300 kPa). BPI (poise or Pa s) can be quickly calculated by linearly adding the contributions of the components included in the formulation.

[0228] Examples of thermoplastic elastomers may include, but are not limited to, random or block poly(propylene / ethylene) copolymers composed primarily of isotactic propylene repeat units having random ethylene distribution therein, SEBS, SBS, SIS, or another styrene (e.g., block) copolymer.

[0229] Flow curves were prepared for formulations containing 50% high molecular weight starch-based material with 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 formulations had the compositions shown in Table 4 below. [Table 5]

[0230] The rheological properties of the blend were very similar to those calculated, e.g., using the BPI values, a BPI of 259 was calculated.

[0231] To evaluate the effect of temperature on starch-based materials, 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. [Table 6]

[0232] The primary materials were selected to blend with the prepared starch-based materials to produce formulations suitable for thin fiber spunbonding, meltblowing, and yarn production. In one embodiment, the formulations were prepared at 1000 sec. -1 a shear viscosity of 125 or less, or 95 or less (e.g., 50 to 65 or less) Pa·s at a shear rate of 200 sec (shear rate being typical of commercial line spinneret process characteristics at least for spunbond processes); -1 The shear viscosity may be adjusted to achieve targets of 500, 300, 275, 250, 240, 230, 220, 200, 190, 180, 170, 160, 150, 140, or 130 Pa·s or less (representing other process configurations in a wide variety of commercial spinning processes) at shear rates of 190°C. Such ratings may be at 190°C. As described herein, yarn processes may use formulations with BPI shear viscosity values ​​of less than 600 Pa·s or less than 500 Pa·s, spunbond processes may use formulations with BPI shear viscosity values ​​of less than 300 Pa·s, 250 Pa·s or less, or 225 Pa·s or less, and meltblown processes may use formulations with BPI shear viscosity values ​​of less than 200 Pa·s or less than 180 Pa·s.

[0233] Figure 5 shows flow curves for an exemplary high molecular weight, starch-based polymer material formed from Corn 2, and a constant shear stress line of 100 kPa (a typical manifestation of instability for PP). Figure 5 also shows spinneret hole sizes (e.g., 0.35 mm to 0.6 mm) that may be typical for contemplated use for various spinning processes, as described herein. Shear rates were calculated using a typical throughput rate of 1 g / min per hole. As noted above, PP is reaching its limits in current high-volume commercial processes (i.e., high line speeds). Figure 6, for example, shows additional flow curves for various additives (e.g., PP with various MFI values ​​from 35 to 1600 g / 10 min).

[0234] A blend material particularly suitable for spunbond applications may include a combination of 100 MFI and 500 MFI PP. A blend of 35 MFI and 500 MFI PP may also be used as a thermoplastic polymer diluent material with specifically selected melt flow index characteristics. Table 6 below shows the melt flow index of the blend material at different shear rates (100, 1000, and 10,000 sec ) at 190°C. -1 ) shows the shear viscosities for exemplary blend components. [Table 7]

[0235] Table 7 below shows the estimated shear viscosity values ​​(1000 s) for different compositions, which are blends of starch-based materials with 35 MFI polypropylene (PP) (50 / 50, 35 / 65, 25 / 75). -1 ) is indicated. [Table 8]

[0236] As shown in various flow curves, starch-based materials exhibit very high viscosities at low shear rates (e.g., 100 sec -1 , 10sec -1, or less), and have very high viscosities at applicable strain rates. Formulations (e.g., masterbatches) containing 25% starch-based material in 35 MFI PP have manageable low-shear viscosities that can be further improved by blending with higher MFI PP (e.g., 100-2000 MFI PP). Formulations containing 25% starch-based material, 50% 500 MFI PP, 21% 35 MFI PP, and 4% maleic anhydride PP compatibilizer have been successfully used to spin thin fibers with fiber diameters <16 μm. This same formulation was used to coextrude bicomponent fibers containing 100 MFI PP downward to a 10 / 90 sheath / core ratio. Images of such thin fibers formed are shown in the figure. Bicomponent core / sheath fibers were also formed with PP, PLA, or PE in the sheath and high molecular weight NuPlastiQ in the core. Different types of core / sheath fibers were produced with up to 22% NuPlastiQ in the core. The fibers were drawn down to less than 20 μm, a fiber size suitable for spunbond nonwoven webs. Nonwoven fabrics with weight basis values ​​of 45-50 gsm and 10-15 gsm were also produced from the homopolymer fibers. Fabrics can also be produced from coextruded fibers.

[0237] Figures 7-7A show additional flow curve data for various prepared and tested formulations. These figures demonstrate that low shear viscosities are high for starch-based polymeric materials as described herein, and that they can be reduced by blending with a diluent plasticizer as described herein. The specific target values ​​illustrated in Figure 7A are exemplary initial target points. As described herein, applicants have successfully spun fibers using formulations with BPI values ​​higher than the target values ​​listed in Figure 7A.

[0238] Table 8 shows the process characteristics of the various formulations used to spin the thin fibers. [Table 9] 1, 2, and 3 represent the first, second, and third high molecular weight NuPlastiQ masterbatches. Each masterbatch contained 50% HMW NuPlastiQ, 32%-42% 35MFI PP, 8% compatibilizer, and 0%-10% other additives (e.g., copolymers). Figures 8 and 9 illustrate some such fibers formed.

[0239] Table 9 illustrates data similar to Table 8, but for spun sheath / core fibers. [Table 10]

[0240] Bicomponent fibers can have unusual physical and aesthetic properties that can make them high-value products compared to standard fibers. Such are often achieved by combining polymer properties or taking advantage of differences in properties such as melting points (e.g., by placing the lower-melting-point component in the sheath). Exemplary bicomponent fibers include core / sheath fibers, eccentric core / sheath fibers, side-by-side fibers, segmented pie fibers, and islands-in-the-sea fibers. Others are, of course, also possible. Figures 10-17 illustrate some of the bicomponent fibers that have been formed.

[0241] Referring to the bicomponent fibers of Figures 10-17, the sheath-to-core ratio varied from 50 / 50 to 10 / 90. Those skilled in the art will understand that sheath / core ratios below 10 / 90, such as 5 / 95, or even thinner sheaths, are also possible. Such values ​​refer to the fraction (mass fraction) of material devoted to each geometric segment (e.g., 50% mass in the sheath, 50% mass in the core, or 10% mass in the sheath, and 90% mass in the core). Assuming the densities of the different feeds are approximately equal, such values ​​can also refer to the ratio of the cross-sectional areas of the different geometric portions (e.g., sheath to core). As an example, if a bicomponent sheath / core fiber has a diameter of approximately 15-20 μm (e.g., 18 μm), the core may therefore have a diameter of approximately 13 μm for a 50 / 50 sheath / core ratio (sheath thickness = 2.5 μm). With a 10 / 90 sheath / core ratio, the core would therefore have a diameter of approximately 17 μm, while the sheath would have a thickness of 0.5 μm. While calculations are based on an 18 μm diameter fiber, it will be understood that other sizes are certainly possible. More generally, the core diameter may therefore be 70-90% of the fiber diameter, while the sheath thickness may therefore be 1-15% of the fiber diameter. While the location of the starch-based material was in the core in the exemplified bicomponent fibers, the location may be switched (e.g., starch-based material in the sheath). It will be apparent that in such bicomponent fibers (whether sheath / core or other geometries), the dimensions of the portion of the fiber containing the polymeric starch-based material may be significantly smaller than if the entire fiber were formed from the same composition. It is surprising that the high molecular weight starch-based compositions of the present invention can be extruded, or otherwise, through such small geometries.

[0242] Applicants were surprised and unexpectedly able to spin fibers from compositions containing a large fraction of high molecular weight starch-based material (e.g., having a weight average molecular weight as described herein). The present examples demonstrate the development of a blend using a higher MFI PP homopolymer to dilute the blend, reducing viscosity characteristics and allowing the formation of spunbond filaments or fibers containing 25% starch-based material to 17 microns, a size suitable for the spunbonding process. Additionally, the examples demonstrate the ability to co-extrude such blends with PP, PLA, PBAT, and PE in a sheath / core configuration.

[0243] Formulations containing 25% starch-based materials were melt-tested for 6400 seconds without melt fracture. -1 It has also been observed that the polymer can be processed at very high shear rates of 190°C. Such properties are advantageous because they are not possible with conventional PP materials, which exhibit melt flow instabilities at such high shear rates.

[0244] 18 shows the flow curves of an exemplary formulation containing 25% high molecular weight starch-based material, 50% 500 MFI PP, 21% 35 MFI PP, and 4% compatibilizer at 190° C., including low shear data obtained using a corn and plate rheometer. BPI data for such formulations is shown in Table 10. [Table 11]

[0245] Table 11 shows the effect of including the 500 MFI diluent component on η 0 . [Table 12]

[0246] Although the examples show thin fibers spun with high molecular weight starch-based polymeric materials to which high melt flow index thermoplastic diluent materials are added to reduce shear viscosity, allowing such formulations to be processed at 190-195°C, it may also be possible to process formulations containing higher concentrations of starch-based components at commercial line speeds (i.e., without line slowdowns, which are costly and should be avoided) by increasing the process temperature or adjusting various other parameters (e.g., formulation additives). For example, below 190°C, for 100% high molecular weight starch-based materials, the shear viscosity is too high, leading to excessive pressure. In addition, the extensional viscosity is too high. The extensional viscosity opposes filament drawing and causes the filaments to break just below the spinneret. It may be possible to process such formulations containing 100% (or close to 100%, e.g., 80-100%) of high molecular weight starch-based polymeric material at higher temperatures, e.g., 220°C or higher, as long as degradation of the material can be avoided.

[0247] Example 2 Example 2 illustrates additional spunbond fiber production. Figure 19 shows spin envelope plots for 100 MFI PP and 35 MFI PP, both run at 225°C. The plot also shows 100 MFI PP at 195°C. Using such data and additional knowledge gained, a tenacity target of 1.75 grams per denier (gpd) was established. The 100 MFI PP was observed to have nearly identical rheology to a composition according to the present invention formed from 25% starch-based polymeric material, 21% 35 MFI PP, and 50% 500 MFI PP. Therefore, the 100 MFI curve can be used as a target or template for desired parameters for compositions according to the present invention that will include a starch-based polymeric material. Data suggested that the tenacity of nonwoven fabrics prepared in previous tests was less than 0.8 gpd. To measure tenacity, filaments were collected directly below the aspirator. The data shown in Figure 19 indicates that for fibers sized between 18 and 20 μm, spinning speeds of 2500 MPM or greater are desirable, which can be achieved with a flow through the system of 0.7 g / min / hole or greater.

[0248] The extrusion section of the pilot production line was used to extrude onto a feed roll to measure tenacity. In contrast to aspirators, which rely on interfilament friction, feed rolls provide a well-defined spinning rate. Samples were run at 195°C in a homopack at 0.7 g / min / hole and a bicopack at a slightly higher g / min / hole value. It was observed that the starch-containing blends could run up to approximately 2000 MPM, while the 100 MFI PP could run up to 2500 MPM. A 50 / 50 dry blend of sample CP1199 (a starch-based polymeric material masterbatch described herein) with 500 MFI PP and a 50 / 50 double-blended blend of sample CP1199 (labeled sample 1421 in Figures 19 and 20) with 500 MFI PP gave a tenacity of approximately 1.1 gpd, consistent with the spin envelope shown in Figure 19. Sample 1451 performed best, with a toughness of 1.4 gpd. This formulation differed from Sample 1421 in that some of the 500 MFI PP was replaced with 100 MFI PP in this composition. Specifically, Sample 1451 contained 50% CP1199 starch-based material masterbatch, 20% 100 MFI PP, and 30% 500 MFI PP. The primary factor contributing to the improved toughness was the reduction in the amount of low molecular weight PP (i.e., 500 MFI PP). Not surprisingly, higher spinning speeds also increase toughness, as shown in Figure 19.

[0249] The specific properties of the selected polypropylene can also affect toughness. For example, the thermoplastic polymer with which the starch-based polymer material is blended may be specifically selected for its ability to reduce the strain rate of spinning (e.g., resulting in a more tapered drawing profile). By way of example, the inclusion of such a thermoplastic polymer at a 10% concentration in the blend may increase toughness by 15%. For example, the inclusion of Vistamaxx may increase toughness to some extent (but at the expense of additional cost and a higher BPI). Sample 1451 already exhibits a higher BPI than Sample 1421. Additionally, the zero-shear viscosity of any such sample should be greater than the target, since low-shear viscosity is important for drawing the fiber down the spinneret.

[0250] A summary of the rheological data for the samples for which toughness was measured is shown in Table 12 below. [Table 13]

[0251] The copolymer was added to the blend in the extruder. As noted above, Samples 1451 and 1450 contained nominally similar components. Sample 1450 contained a polypropylene copolymer having both isotactic and atactic structures (e.g., an MFI of less than about 1000, or less than about 100 g / 10 min, when measured at 230°C under a load of 2.16 kg), which allowed for a reduced shear rate in spinning (e.g., resulting in a more tapered draw profile relative to the typical neck draw of polypropylene) compared to the polypropylene used in Sample 1451.

[0252] Figure 20 shows the Rheotens plots of the various samples. The Rheotens data shows that sample 1451 outperformed the others, but there is significant variation shown in the test data. Each sample was run three times, and the best of each was taken for comparison.

[0253] In addition to the benefits provided by the improved sustainability afforded by replacing some of the conventional thermoplastic resin materials in spinnable formulations with the high molecular weight starch-based polymers of the present invention, other benefits are also provided by such compounding of the formulation. For example, extrusion speed may be improved by extending the onset of melt flow instability at higher shear rates (increased power output). Additionally, rheological data indicate advantageously high critical shear stresses associated with such high molecular weight starch-based materials, which may provide an improvement over the typical onset of melt flow instability. During experiments conducted, applicants demonstrated that the extrusion speed of 6400 s at 190°C without observable instability. -1 It has been reported that polypropylene exhibits melt flow instability at 100 kPa. For example, if the starch-based polymeric material itself can exhibit a critical shear stress of 300 kPa or more, its inclusion at even a 25% level in the blend being spun can result in an increase in the critical shear stress from about 100 kPa for the polypropylene composition alone to approximately 150 kPa for the blend containing the starch-based polymeric material. This allows for processing at elevated shear rates, higher line speeds, etc., without the onset of melt flow instability.

[0254] The strength of nonwoven webs formed from the thin fibers described herein can be increased, for example, through adjustments to the composition, the post-extrusion bonding method employed (e.g., details of the calendering or other bonding process), or other parameters. Strength can also be improved through improved formulation (e.g., taking advantage of the higher molecular weight of starch-based materials), by increasing elongation (e.g., supplemental materials available under the trade name Vistamaxx, random poly(propylene / ethylene) copolymers composed primarily of isotactic propylene repeat units with random ethylene dispersions therein, or others), increasing process temperatures while reducing the amount of the highest MFI component, blending high molecular weight starch with low molecular weight starch (so that the concentration of the high melt flow index thermoplastic component can be reduced), or by adding additives configured to do a combination of the above.

[0255] The present embodiments may accelerate the biodegradation of polypropylene or other non-biodegradable components of the blend, enhance the biodegradability of other materials (e.g., polyester), improve flexibility, improve wettability and / or absorbency compared to polypropylene alone, replace a portion of fossil fuel resins (e.g., polypropylene) with renewable starch-based components, and / or reduce costs.

[0256] Filament diameter uniformity was excellent, even at 16 μm. In some fibers, ridges were observed on the outer surface or within the formed fiber, as shown in the figures. The ridges typically varied in diameter from 1 to 4 μm. Such ridges can be desirable and advantageous, at least in some embodiments. If ridges are undesirable, they can be covered (e.g., by applying a sheath in bicomponent fibers) or by adjusting various parameters as described herein.

[0257] Example 3 Example 3 demonstrates meltblown fiber production. Meltblown fibers were produced using the same or similar masterbatches used in the spunbond examples. The masterbatches contained 50% NuPlastiQ, 42% 35 MFI polypropylene, and 8% compatibilizer. The masterbatches were blended with 1550 MFI polypropylene in various ratios (10 / 90, 20 / 80, 30 / 70, 40 / 60, and 50 / 50) up to 50:50 and used to produce meltblown fibers, the results of which are shown in Table 13. For the meltblown tests, two masterbatches were tested. [Table 14]

[0258] The final 50 / 50 sample was prepared using the second masterbatch sample, while the first 50 / 50 sample and samples containing 5-25% NuPlastiQ were prepared using the first masterbatch sample. The meltblowing line contained a 31-hole spin pack with a 0.4 mm diameter die orifice and was run at 0.19 g / min / hole with 230°C air at a polymer melt temperature of 205°C. Fabrics were made from the meltblown fibers with fabric weights of approximately 18 gsm ± 4 gsm. As shown in Table 13, fiber diameters ranged from 2 to 4 μm. Grams per hole can more commonly range from 0.05 to 1 g / min / hole, or from 0.13 g / min / hole to 0.5 g / min / hole. Polymer melt temperatures can more commonly be below 225°C, but are typically above 230°C for polypropylene. The BPI values ​​of the two NuPlastiQ samples were 248 and 350 Pa·s, respectively, both of which are suitable for meltblowing after appropriate dilution. The machine direction (MD) tensile strength of the pure polypropylene sample (1550 MFI PP in Table 13) and the sample containing 20% ​​NuPlastiQ (40 / 60 in Table 13) were both measured at 1.1 kg. The elongation was measured at 13.2% and 31.5% for these samples, respectively.

[0259] Example 4 Example 4 illustrates yarn production. The masterbatch of Sample 1631 used in the melt-blowing examples was used to produce yarn fibers. The masterbatch contained 50% NuPlastiQ, 42% 35 MFI polypropylene, and 8% compatibilizer. The masterbatch was blended with additional 35 MFI polypropylene and 100 MFI polypropylene to provide blends containing 50% masterbatch and 25% each of the added 35 MFI polypropylene and 100 MFI polypropylene. The formulation contained 25% starch-based polymer material (NuPlastiQ). The system was run with a 72-hole spin pack and a 0.35 mm die orifice diameter at a melt temperature of 205°C. The spinning speed during the spinning portion of the yarn process was 638 m / min, producing as-spun yarn fibers with a diameter of approximately 60 μm. For the draw portion of the process, the draw temperature was 100°C, with a draw ratio of 2.8x and a take-up speed of 1750 m / min. The produced fiber was 2.5 denier per filament (dpf), had a tenacity of 2.49 gpd, and an elongation of 70.38%. Such yarn fibers can be used as precursors for the production of airlaid or wet-laid substrates, carded nonwovens, cut or crimped fibers for weaving, knitting, etc.

[0260] In addition to yarn production using the blends described above, similar yarns can be produced from (1) a compound prepared by blending 50% masterbatch with 50% 100 MFI polypropylene, or (2) a compound prepared by blending 50% masterbatch with 50% 35 MFI polypropylene.

[0261] Features of any disclosed embodiment or claim can be used in combination with each other without restriction. It will be understood that the scope of the present disclosure extends to rewriting any claim to depend on any other claim, including multiple dependencies from any combination of other claims, and / or combining multiple claims together. This also extends to any individual feature or combination of features of any embodiment, as described in the "Summary of the Invention" and "Description of the Invention" sections. The scope of the present disclosure extends to inserting and / or deleting any feature or combination of features from any claim or described embodiment for insertion into another claim or embodiment, or for drafting a new claim that includes any combination of such features from the other claims or embodiments.

[0262] It will also be understood that the claimed invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. 1. A method for spinning a composition comprising a starch-based polymeric material to produce a spunbond nonwoven fabric from said composition, said method comprising: providing a composition that is a blend of a starch-based polymeric material and at least one thermoplastic polymer comprising polypropylene; melt-spinning the composition to produce a fiber comprising the starch-based polymer material, wherein the composition is melt-spun for 200 seconds. －１ and producing a polymer having a shear viscosity of 300 Pa·s or less at 190°C at a process shear rate of 1000 Pa·s or less to avoid the development of melt flow instabilities during melt spinning.

2. The composition is －１ A shear viscosity of 300 Pa s or less at 190°C and a shear viscosity of 1000 s －１ 10. The method of claim 1, wherein the cellulose fiber exhibits a shear viscosity of 125 Pa s or less at 190°C at a spinneret shear rate of 100 rpm.

3. The method described in claim 1, wherein the starch-based polymer material is a high molecular weight starch-based polymer material having a weight average molecular weight of at least 3 million g / mol.

4. 10. The method of claim 1, wherein the at least one thermoplastic polymer comprises a polymer having a melt flow index greater than 100 g / 10 min when measured at 230°C under a load of 2.16 kg.

5. 10. The method of claim 1, wherein the polypropylene comprises at least two grades, a first grade having a melt flow index of 400 g / 10 min to 600 g / 10 min when measured at 230°C under a 2.16 kg load, a second grade having a melt flow index of less than 100 g / 10 min when measured at 230°C under a 2.16 kg load, and optionally a third grade having a melt flow index of 75 g / 10 min to 125 g / 10 min when measured at 230°C under a 2.16 kg load.

6. 6. The method of claim 5, wherein the polypropylene further comprises additional grades containing both isotactic and atactic structures having a melt flow index of less than 1000 g / 10 min when measured at 230° C. under a load of 2.16 kg.

7. The method described in claim 1, wherein the starch-based polymeric material has a moisture content including any bound water of 2% or less.

8. The method of claim 1, wherein the method produces fibers having a diameter of 10 μm to 50 μm.

9. The method described in claim 1, wherein the starch-based polymer material is contained in the composition in an amount of up to 60% by weight.

10. 1. A polymer blend for use in producing a spunbond nonwoven fabric, said blend comprising: a starch-based polymeric material having a moisture content of 2% or less, including any bound water; a thermoplastic polymer material comprising polypropylene having a melt flow index of at least 35 g / 10 min when measured at 230° C. under a load of 2.16 kg, configured to plasticize the starch-based polymer material; A blend wherein the starch-based material is uniformly dispersed within the thermoplastic polymer material.

11. The starch-based polymeric material exhibits a zero shear viscosity of at least 10 Pa·s at a process temperature of 170°C to 210°C, and the shear viscosity is greater than 1000 sec －１ 11. The blend of claim 10, wherein the viscosity of the blend is reduced to 125 Pa s or less at the process temperature at a shear rate of 125 Pa s or less.

12. 11. The blend of claim 10, wherein the starch-based polymeric material is present in an amount of up to 60% by weight of the blend.

13. The blend is heated at 190°C for 1000 seconds. －１ 11. The blend of claim 10, wherein the blend exhibits a shear viscosity of 125 Pa s or less at 1000 kJ / min.

14. A spunbond nonwoven fabric composed of fibers, the fibers comprising: a starch-based polymeric material present in an amount of up to 60% by weight; a thermoplastic polymer material comprising polypropylene having a melt flow index of at least 35 g / 10 min when measured at 230° C. under a load of 2.16 kg, configured to plasticize the starch-based polymer material; A spunbond nonwoven fabric, wherein the starch-based material is uniformly dispersed within the thermoplastic polymer material.

15. 15. The spunbond nonwoven fabric of claim 14, wherein the fibers have a diameter of up to 50 μm.

16. 15. The spunbond nonwoven fabric of claim 14, wherein the fibers are bicomponent fibers, the bicomponent fibers having a diameter of 50 μm or less and of a sheath / core geometry, and the core or sheath comprises the starch-based polymeric material.

17. 15. The spunbond nonwoven fabric of claim 14, wherein the thermoplastic polymer material is not biodegradable by itself, and the starch-based material enhances the biodegradability of the thermoplastic polymer material that is not biodegradable by itself, such that at least 20% of the thermoplastic polymer material that is not biodegradable by itself biodegrades within 3 years under ASTM D-5338 or ASTM D-5511.

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