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Toughened Polylactic Acid Polymers and Copolymers

a polylactic acid polymer and copolymer technology, applied in the field of polymer compositions, can solve the problems of poor mechanical properties of blends, brittle glassy objects of plla at room temperature, and general stiffness of objects, and achieves the effects of reducing the number of elongation

Inactive Publication Date: 2007-08-09
TEPHA INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a way to make PLA and PLA copolymers stronger and more flexible by blending them with poly-4-hydroxybutyrate. This results in a toughened composition that is easier to break and has lower stiffness than pure PLA. This makes it easier to make objects from these compositions.

Problems solved by technology

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.
However, these objects are generally stiff due to the relatively high tensile modulus of the polymer.
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.

Method used

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  • Toughened Polylactic Acid Polymers and Copolymers
  • Toughened Polylactic Acid Polymers and Copolymers

Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation of a Blend of PLA Polymer and P4HB Polymer

[0041]PLLA polymer (Resomer L 214 lot #1012474, Boehringer Ingelheim, Germany) with a viscosity of 5.9 dl / g (IV) was compounded with P4HB (poly-4-hydroxybutyrate, Mw 178,000, 2.3 dl / g (IV) (Tepha, Inc., Cambridge, Mass.) using a Leistritz 18 mm twin screw extruder (24:1 L / D). Compounding was undertaken at a temperature of 110° C. at the feed, and 230° C. at the die. The polymers were mixed i the molten state, extruded into large diameter filament, quenched into a water bath set at 5-20° C., and cut into 2-5 mm length pellets. The PLLA and P4HB were compounded in the following three different ratios by weight: PLLA (90%):P4HB (10%); PLLA (77.5%):P4HB (22.5%); and PLLA (10%):P4HB (90%).

example 2

Preparation of a Blend of PLA Polymer and P4HB Polymer

[0042]PLLA polymer (Resomer L 214 lot #1002260, Boehringer Ingelheim, Germany) with a high intrinsic viscosity of 7.0 dl / g (IV) was dry mixed with P4HB (poly-4-hydroxybutyrate, Mw 170,000, 2.1 dl / g (IV) Tepha, Inc., Cambridge, Mass.) by tumble mixing at room temperature. The PLLA and P4HB were compounded in the following three different ratios by weight: PLLA (90%):P4HB (10%); PLLA (77.5%):P4HB (22.5%); and PLLA (10%):P4HB (90%).

example 3

Fiber Extrusion of PLA / P4HB Blends

[0043]The blends prepared in Example 1 were extruded into monofilament fiber using the following method. The blends were dried under vacuum overnight to less than 0.01% (w / w) water. Dried pellets of the blended polymers were fed into an extruder barrel of an AJA (Alex James Associates, Greer, S.C.) ¾″ single screw extruder (24:1 L:D, 3:1 compression) equipped with a Zenith type metering pump (0.16 cc / rev) and a die with a single hole spinneret (0.026″, 2:1 L:D) under a blanket of nitrogen. The 4 heating zones of the extruder were set at 140°, 190°, 200° and 205° C. The block, metering pump and the die were maintained at a constant temperature, preferably 180-250° C. Pump discharge pressure was kept below 1500 psi by controlling the temperatures and the speed of the metering pump. The fiber spinning system was set up with a drop zone, air quench zone, a guide roll, three winders and a pickup. The fiber was oriented in-line with extrusion by drawing i...

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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.

Description

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 referr...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B29B9/08C08G63/08
CPCA61L17/12A61L27/26A61L29/049A61L31/041A61L31/10A61L31/148A61L31/18C08L67/04C08L2666/18C08K3/014A61K47/34A61L15/26A61L17/105A61L27/18A61L29/06A61L31/06C08G63/06C08K5/0016C08K5/005C08K5/0083
Inventor RIZK, SAIDMARTIN, DAVID P.HO, KICHERLGANATRA, AMITWILLIAMS, SIMON F.
Owner TEPHA INC
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