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  Water stable fibers and articles comprising starch, and methods of making the sameUSPTO Application #: 20070082573Title: Water stable fibers and articles comprising starch, and methods of making the same Abstract: Water stable fibers and articles made therefrom are formed from a thermoplastic composition comprising destructured starch, polyhydric alcohol, triglyceride, and optionally acid. Processes for making water stable compositions may comprise melt extruding a mixture of destructured starch, polyhydric alcohol, triglyceride, and optionally acid, to form an extrudate, and heating the mixture, extrudate, or both to provide a water stable article. (end of abstract) Agent: The Procter & Gamble Company Intellectual Property Division - Cincinnati, OH, US Inventors: Isao Noda, Michael M. Satkowski, William M. Allen, James T. Knapmeyer USPTO Applicaton #: 20070082573 - Class: 442361000 (USPTO) Related Patent Categories: Fabric (woven, Knitted, Or Nonwoven Textile Or Cloth, Etc.), Nonwoven Fabric (i.e., Nonwoven Strand Or Fiber Material), Including Strand Or Fiber Material Which Is A Monofilament Composed Of Two Or More Polymeric Materials In Physically Distinct Relationship (e.g., Sheath-core, Side-by-side, Islands-in-sea, Fibrils-in-matrix, Etc.) Or Composed Of Physical Blend Of Chemically Different Polymeric Materials Or A Physical Blend Of A Polymeric Material And A Filler Material The Patent Description & Claims data below is from USPTO Patent Application 20070082573. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. Provisional Application No. 60/725,424, filed 11 Oct. 2005. FIELD OF THE INVENTION [0002] The present invention relates to fibers made from thermoplastic starch compositions, and articles made therefrom. The fibers and articles are water stable, or may be rendered so. The invention also relates to methods of making the fibers and articles. BACKGROUND OF THE INVENTION [0003] There have been many attempts to make starch-containing fibers, particularly on a high speed industrial level. However, starch fibers can be much more difficult to produce than films, blow-molded articles, and injection-molded articles containing starch because the material and processing characteristics for fibers are much more stringent. For example, local strain rates and shear rates can be much greater in fiber production than in other processes. Additionally, a homogeneous composition may be required for fiber spinning. For spinning fine fibers, small defects, slight inconsistencies, or non-homogeneity in the melt are typically not acceptable for current, commercially viable processes. [0004] In recent years, attempts have been made to process starch on standard equipment and using existing technology known in the plastic industry. Fibers comprising starch may be desired over conventional plastics for a variety of reasons. Unpredictable fluctuations in price and availability of petroleum and its derivatives have created serious disruptions to the stable supply of petroleum-based polymers used in making synthetic fibers, for example, those based on polyolefins. Starch also has material properties not typically provided by conventional polyolefin plastics, including higher hydrophilicity (such as for improved absorbency), as well as affinity and compatibility with other materials not normally compatible with polyolefins. Starch may, in some forms, also provide consumer-related benefits, like easy disposability and/or flushability, and/or socially and environmentally relevant properties, like bio-sourcing and biodegradability. Starch may also provide a low-cost alternative to conventional petroleum-based materials, for example polypropylene. [0005] In conventional processes, starch is typically combined with one or more plasticizers or other process aids to render it thermoplastic for processing, for example by melt spinning or other melt extrusion techniques. Unfortunately, thermoplastic starch (TPS) is highly susceptible to moisture. In fact, fibers made of TPS can spontaneously pick up atmospheric moisture and become tacky. When placed in water, TPS fibers from conventional starch blends partially or fully disintegrate within hours. Although methods exist for rendering thermoplastic compositions containing starch more water stable including, but not limited the addition of petroleum based polymers, there remains an unmet need for greater water stability in such compositions and in articles made from such compositions. SUMMARY OF THE INVENTION [0006] In some embodiments, the present invention relates to water stable fibers which are made from thermoplastic polymer compositions comprising destructured starch, and transesterification reaction products formed from a reaction mixture comprising polyhydric alcohol and triglyceride. In some embodiments, the water stable fibers are made from thermoplastic polymer compositions additionally comprising ester condensation reaction products of polyhydric alcohol and acid. [0007] In some embodiments, the invention is directed to a method of making water stable fibers. The method comprises the following series of steps which may be completed in any suitable order. In one step, a mixture of destructured starch, polyhydric alcohol, triglyceride, and acid, is formed. In a further step, the mixture is extruded through a spinneret at an elevated temperature to form fibers. In yet a further step, a transesterification reaction is induced between polyhydric alcohol and triglyceride, and optionally, an ester condensation reaction is induced between polyhydric alcohol and acid. [0008] In some embodiments, articles are made from the fibers of the present invention. Non-limiting examples of articles in include nonwovens. Specific embodiments include personal hygiene articles, absorbent articles, and packaging. [0009] In general, the present invention provides starch-based compositions, fibers and articles in other forms with improved water stability, and compositions and processes for making such water stable compositions and articles. Water stability may be achieved without requiring the use of petroleum based polymers including, but not limited to, polyolefins. Water stability can provide a variety of consumer-related benefits. The fibers, compositions and processes may provide a low-cost alternative to conventional petroleum-based materials. These and additional advantages will be more apparent in view of the following detailed description. DETAILED DESCRIPTION [0010] All percentages, ratios and proportions used herein are by weight percent of the composition, unless otherwise specified. All average values are calculated "by weight" of the composition or components thereof, unless otherwise expressly indicated. "Average molecular weight," or "molecular weight" for polymers, unless otherwise indicated, refers to weight average molecular weight. Weight average molecular weight, unless otherwise specified, is determined by gel permeation chromatography. [0011] "Copolymer" as used herein is meant to encompass copolymers, terpolymers, and other multiple-monomer polymers. [0012] "Reactant" as used herein refers to a chemical substance that is present at the start of a chemical reaction. [0013] "Mixture" as used herein refers to a mixture of two or more of any of a defined group of components, unless otherwise specified. [0014] "Biodegradable" as used herein refers to the ability of a compound to ultimately be degraded completely into CH.sub.4, CO.sub.2 and water or biomass by microorganisms and/or natural environmental factors. [0015] "Fiber" as used herein includes staple fibers, fibers longer than staple fibers that are not continuous, and continuous fibers, which are sometimes referred to in the art as "substantially continuous filaments" or simply "filaments". The method in which the fiber is prepared will determine if the fiber is a staple fiber or a continuous filament. [0016] "Monocomponent fiber" as used herein, refers to a fiber formed from using one or more extruders from only one polymer. This is not meant to exclude fibers formed from one polymer to which small amounts of additives have been added. Additives may be added to the polymer for the purposes of providing the resulting fiber with coloration, antistatic properties, lubrication, hydrophilicity, and the like. [0017] "Multicomponent fiber" as used herein refers to a fiber formed from two or more different polymers that are extruded from separate extruders and spun together to form one fiber. [0018] "Bicomponent fibers" are one type of multicomponent fiber, and are formed from two different polymers. Bicomponent fibers may sometimes be referred to as "conjugate fibers" or "multicomponent fibers". Bicomponent fibers may be comprised of polymers that are substantially constantly positioned in distinct zones, both across the cross-section of the bicomponent fibers and along their length. Non-limiting examples of such bicomponent fibers include, but are not limited to: sheath/core arrangements, wherein one polymer is surrounded by another; side-by-side arrangements; segmented pie arrangements; or even "islands-in-the-sea" arrangements. Each of the aforementioned polymer arrangements is known in the art of multicomponent (including bicomponent) fibers. [0019] Bicomponent fibers can be splittable fibers; such fibers are capable of being split lengthwise before or during processing into multiple fibers with each of the multiple fibers having a smaller cross-sectional dimension than that of the original bicomponent fiber. Splittable fibers have been shown to produce softer nonwoven webs due to their reduced cross-sectional dimensions. Representative splittable fibers useful in the present invention include type T-502 and T-512 16 segment PET/nylon 6, 2.5 denier fibers, and type T-522 16 segment PET/PP splittable fibers, all of which are available from Fiber Innovation Technology, Johnson City, Tenn. Continue reading... Full patent description for Water stable fibers and articles comprising starch, and methods of making the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Water stable fibers and articles comprising starch, and methods of making the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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