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  Toughened polylactic acid polymers and copolymersUSPTO Application #: 20070182041Title: Toughened polylactic acid polymers and copolymers Abstract: Toughened compositions of PLA and PLA copolymers are disclosed, which also have low tensile modulus values and greater elongation to break. These toughened compositions are prepared by blending PLA and PLA copolymers with poly-4-hydroxybutyrate, and copolymers thereof. Blending of poly-4-hydroxybutyrate with PLA and its copolymers has been found to impart advantageous properties to the resulting blend. These compositions, and objects formed from these compositions, have improved toughness and lower stiffness than polylactic acid polymers or copolymers alone. (end of abstract)
Agent: Patrea L. Pabst Pabst Patent Group LLP - Atlanta, GA, US Inventors: Said Rizk, David P. Martin, Kicherl Ho, Amit Ganatra, Simon F. Williams USPTO Applicaton #: 20070182041 - Class: 264 6 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070182041. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001]The present application claims priority of U.S. Ser. No. 60/747,144 filed May 12, 2006, U.S. Ser No. 60/765,840, filed Feb. 7, 2006, and U.S. Ser. No. 60/765,808 filed Feb. 7, 2006. FIELD OF THE INVENTION [0002]The present invention generally relates to polymeric compositions that can be processed into various extruded as well as molded forms, including fibers, tubes, films, nonwovens, injection molded or thermoformed components, which products have substantially uniform physical properties, and physical and thermo-mechanical integrity. The compositions comprise polylactic acid polymers or copolymers and polymers or copolymers comprising 4-hydroxybutyrate. BACKGROUND OF THE INVENTION [0003]Polylactic acid (PLA) is an aliphatic polyester that can be prepared, for example, by direct condensation of lactic acid, azeotropic dehydrative condensation, and by ring-opening polymerization of lactide. In the latter case, the product is sometimes referred to as polylactide. The relative proportions of the optically active enantiomers, D- and L-lactic acids, which are incorporated into the polymer, determine the specific properties of PLA. Varying the enantiomer proportions can result in polymer compositions that are amorphous or up to about 40% crystalline, with glass transition temperatures (Tg) ranging from about 50.degree. C. to 80.degree. C., and melting points (Tm) ranging from about 130.degree. C. to 180.degree. C. [0004]Elongation to break of poly-L-lactic acid (PLLA) is, however, typically just several percent. The polymer has a glass transition temperature well above room temperature, and therefore shaped objects of PLLA tend to be brittle and glassy at room temperature. Several methods have been used to increase the elongation at break of PLLA. Melt processing of the polymer, followed by orientation at temperatures above the glass transition temperature, can result in shaped objects with somewhat improved elongation to break. However, these objects are generally stiff due to the relatively high tensile modulus of the polymer. [0005]Incorporation of D-lactic acid in combination with orientation can yield further improvement. For example, incorporation of D-lactic acid at a level of 2% in an oriented film increases the elongation at break to 5-10%. The latter may be further increased to 78-97% with incorporation of about 6% D-lactic acid. Orientation and incorporation of D-lactic acid has also been used to improve the toughness of fibers of PLA. Melt extruded fibers of PLA with elongation to break of 50%-60% are commercially available under the trade name of Ingeo.TM. PLA (Cargill, Minn.). The modulus of these objects is however still relatively high. [0006]Polymer scientists have also investigated blends of PLA with other polymers and additives to improve PLA properties, for example, to improve toughness and decrease the stiffness. For example, blends of PLA with other PLAs and copolymers, polycaprolactone, poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), poly-R-3-hydroxybutyrate (PHB), poly-R,S-3-hydroxybutyrate, poly-3-hydroxyoctanoate, poly(hexamethylenesuccinate), poly(butylene succinate), poly(ethylene/butylene succinate), poly(ethylene oxide), poly(phosphazene), poly(sebacic anhydride), poly(vinyl alcohol) and poly(vinyl acetate) have all been reported (Tsuji, H., Polyesters, III, 4:129-177 (2002)). Blends of PLA comprising multiple components have also been reported. For example, U.S. Pat. No. 5,939,467 to Wnuk et al. discloses blends comprising PLA, polyhydroxyalkanoates, and polyurethane or polycaprolactone. These approaches have met with varying levels of success because many polymers are immiscible when blended, creating undesirable phase separation during processing, and/or such blends exhibit poor mechanical properties. These difficulties are exacerbated in the processing of fibers and films, where processing time is often much shorter. [0007]It would therefore be desirable to identify polymers that could be blended with PLA and its copolymers, which provide a blend with improved toughness and lower stiffness. [0008]It is therefore an object of this invention to provide toughened blends of PLA and its copolymers. [0009]It is another object of this invention to provide blends of PLA and its copolymers with lower stiffness values. [0010]It is still yet another object of this invention to provide blends of PLA and its copolymers with increased elongation to break. [0011]It is yet another object of this invention to provide blends of PLA and its copolymers that can be processed into shaped objects, such as fibers, films, molded items, and nonwovens. SUMMARY OF THE INVENTION [0012]Toughened compositions of PLA and PLA copolymers are disclosed, which also have low tensile modulus values and greater elongation to break. These toughened compositions are prepared by blending PLA and PLA copolymers with poly-4-hydroxybutyrate, and copolymers thereof. Blending of poly-4-hydroxybutyrate with PLA and its copolymers has been found to impart advantageous properties to the resulting blend. These compositions, and objects formed from these compositions, have improved toughness and lower stiffness than polylactic acid polymers or copolymers alone. BRIEF DESCRIPTION OF THE DRAWINGS [0013]FIG. 1 is the chemical structure of poly-4-hydroxybutyrate (P4HB, TephaFLEX.RTM. biomaterial). [0014]FIG. 2 shows some of the known biosynthetic pathways for the production of P4HB. Pathway enzymes are: 1. Succinic semialdehyde dehydrogenase; 2. 4-hydroxybutyrate dehydrogenase; 3. diol oxidoreductase; 4. aldehyde dehydrogenase; 5. Coenzyme A transferase and 6. PHA synthetase. DETAILED DESCRIPTION OF THE INVENTION [0015]Toughened blends comprising PLA and its copolymers have been developed that have improved properties. I. Definitions [0016]Poly-4-hydroxybutyrate" as generally used herein means a homopolymer comprising 4-hydroxybutyrate units. It may be referred to herein as P4HB or TephalFLEX.RTM. biomaterial (manufactured by Tepha, Inc., Cambridge, Mass.). [0017]Copolymers of poly-4-hydroxybutyrate" as generally used herein means any polymer comprising 4-hydroxybutyrate with one or more different hydroxy acid units. Continue reading... Full patent description for Toughened polylactic acid polymers and copolymers Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Toughened polylactic acid polymers and copolymers 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. Start now! - Receive info on patent apps like Toughened polylactic acid polymers and copolymers or other areas of interest. ### Previous Patent Application: Apparatus for the gasification of liquids Next Patent Application: Production method of dental ceramics material Industry Class: Plastic and nonmetallic article shaping or treating: processes ### FreshPatents.com Support Thank you for viewing the Toughened polylactic acid polymers and copolymers patent info. 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