Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
  • C08L3/02—Starch; Degradation products thereof, e.g. dextrin
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L89/00—Compositions of proteins; Compositions of derivatives thereof

Definitions

• the present invention relates to bio based, biodegradable polymer compositions comprising poly(lactic acid) and further components of natural origin which exhibit improved mechanical properties as compared to currently available similar material.
• the present invention also relates to products, items or articles made on the basis of said compositions.
• Packaging material and disposable beakers, cups and cutlery are used nowadays widely and allow that food material may be sold and/or consumed under hygienic conditions.
• Such disposable materials and objects are highly estimated by the consumers and the retailers, since they may be simply disposed after use and do not have to be washed and cleaned like conventional dishes, glasses or cutlery.
• biodegradable polymers are already known in the state of the art and comprise materials on the basis of e.g. poly(glycolic acid), poly(epsilon- caprolactone), poly(lactic acid), and polydioxanone.
• the production of these polymers is, however, rather cumbersome and expensive, so that the use thereof is presently mainly restricted to high value medical applications requiring bio absorbable materials.
• a few biodegradable resins have been used in applications such as described above but cost has made them unaffordable by the consumers.
• US 6,235,815 provides biodegradable polymer compositions made of mixtures of native and thermoplastic starch in relatively high proportions (ca 50 % weight), poly(lactic acid) and plasticizer like polyester amide type plasticizers. It has been observed, however, that the necessity to use plasticizers does not provide the expected reductions manufacture costs.
• biodegradable polylactide resin compositions comprising at least one protein like e.g. silk protein, gelatin, keratin, elastin, gluten or zein so that a polylactide, in other terms a poly(lactic acid) composition having excellent biodegradability can be obtained while maintaining good physical properties and strengths.
• protein like e.g. silk protein, gelatin, keratin, elastin, gluten or zein
• an object of the present invention is to provide a cost and price attractive composition or article, which composition or article is degraded in a natural environment in a time period which is significantly shorter as compared to the time period required for the degradation of conventional plastic materials, such as e.g. polyethylene or polypropylene.
• composition will allow biodegradation in period of time not to exceed 180 days, one of the time requirements set by the US specification set by ASTM (ASTM 6400 D99). Moreover, such a composition should also enable production of bags, bottles or cutlery, exhibiting desired properties for the respective purpose.
• composition comprising poly(lactic acid), starch and protein material like e.g. gluten and which is obtainable by the process according to claim 1 and following.
• a composition or an article of the present invention is biodegradable when exposed to specific environmental conditions, such as composting, which will result in a loss of some properties that may be measured by standard methods appropriate to the plastic and in the application in a period of time that determines its classification.
• composting is a managed process that controls the biological decomposition and transformation of biodegradable materials into humus-like substance called compost: the aerobic mesophilic and thermophilic degradation of organic matter to make compost; the transformation of biologically decomposable material through a controlled process of bio oxidation that proceed through mesophilic and thermophilic phases and results in the production of carbon dioxide, water, minerals, and stabilized organic matter (compost or humus) (ASTM Terminology) Consequently all main components, poly(lactic acid), starch and proteins will be degraded to small organic fragments which will create stabilized organic matter and will not introduce any hazard or heavy metals into soil.
• objects made from the composition of the present invention will not contribute to a further increase of refuse dumps; on the contrary they will allow creation of organic fertilizers such as compost, while such objects simultaneously provide all advantages of disposable objects highly estimated by the consumers and producer.
• Objects made of a composition according to the present invention may be disposed after use, are essentially of lightweight, and have not to be transported to a location where they have to be cleaned.
• objects made from a composition according to the present invention provide the advantage that objects thrown away in parks or at the beach will degrade and will vanish after some time.
• this invention should not be publicize as a license to litter the environment.
• compositions or an article according to the present invention can be produced completely from renewable sources.
• a composition according to the present invention may be adapted to various processing methods known in the art.
• compositions according to the present invention provide improved mechanical properties not inherent to poly(lactic acid) and provide improvements with respect to the processability, production costs and heat or mechanical resistance along with improved flexibility and ductility.
• biodegradable polymer pertains to a degradable polymer material in which the degradation results from the action of naturally occurring microorganisms such as bacteria, fungi, and algae.
• a degradable polymer material is a material designed to undergo a significant change in its chemical structure under specific environmental conditions, resulting in a loss of some properties that may be measured by standard tests methods appropriate to the plastic and the application in a period of time that determines its classification. Depending on the additional components present in the composition and the dimensions of the object made from said biodegradable material, the time period required for degradation will vary and may also be controlled when desired.
• the time span for biodegradation will be significantly shorter than the time span required for a degradation of objects made from conventional plastic materials having the same dimensions, such as e.g. polyethylene, which have been designed to last for as long as possible.
• cellulose and Kraft paper is to biodegrade within 83 days in a compost environment.
• Our formulation is to biodegrade in a shorter period of time and will pass the tests required by ASTM 6400 D99, which demand that compostable plastic or polymer material would biodegrade within less than 180 days.
• Articles made from e.g. PE would not degrade under normal composting conditions and PLA-based article would degrade in compost environment in weeks (about 6 to 8 weeks).
• Biodegradable polymers are comprised of components which are reduced in film or fiber strength by microbial catalyzed degradation.
• the biodegradable polymers are reduced to monomers or short chains, which are then assimilated by the microbes. In an aerobic environment, these monomers or short chains are ultimately oxidized to CO 2 , H 2 O 5 and new cell biomass. In an anaerobic environment the monomers or short chains are ultimately oxidized to CO 2 , H 2 O, acetate, methane, and cell biomass.
• Successful biodegradation requires direct physical contact between the biodegradable polymers and the active microbial population or the enzymes produced by the active microbial population.
• certain minimal physical and chemical requirements such as suitable pH, temperature, oxygen concentration, proper nutrients, and moisture level must be met (cf. US Patent 6,020,393).
• the present invention also relates to a substantially or totally bio based biodegradable article or composition.
• bio based means that the major weight portion if not the whole of such an article or composition consists of naturally occurring components like starch, e.g. corn or wheat starch, i.e. a material simply extracted from their natural source without any subsequent chemical treatment; or components such poly(lactic acid) or esters thereof which results from e.g. enzymatic treatment of naturally occurring material like starch and subsequent polymerization and/or subsequent ester formation if any.
• biodegradable polymer composition according to the present invention can be obtained by means of a process which comprises
• PLA poly(lactic acid) polymer
• starch and protein material in such ratios that PLA/starch blend represents min. 95 % weight of the above three components and that starch represents min. 23 % weight of PLA;
• the invention further provides a process for improving processability of biodegradable polymers based on poly(lactic acid) polymer (PLA) 5 starch and protein material , which comprises subjecting said components to a process defined here above.
• PLA poly(lactic acid) polymer
• the invention also provides a process for manufacturing substantially or totally bio based biodegradable items or articles with improved mechanical properties which comprises subjecting the polymeric composition prepared according to the process defined here above to an operation selected from the group of forming, molding, injection, molding, extrusion, extrusion coating and thermoform extrusion.
• these polymer compositions show significantly improved process ability and/or physical and/or mechanical properties when compared to prior known compositions made of same or similar components but processed in a quite different way and also present in quite different respective ratios (see e.g. US 6,235,815 and US 2004/0034128).
• the composition here above is made of mixtures wherein the protein material is gluten, still more preferably corn gluten or wheat gluten and represents from min. 1 to max. 5 weight % of the PLA/starch blend.
• Proportions of starch in the PLA/starch blend e.g. wheat starch or corn starch represent preferably from min 15 to 55 weight % of the said blend and still more preferably from min. 25 to max. 45 weight % of the said blend.
• Starch can be either native or thermoplastic starch.
• Poly(lactic acid) may be represented by the following structure:
• Poly(lactic acid) can be prepared according to any method known in the state of the art.
• poly(lactic acid) can be prepared from lactic acid and/or from one or more of D-lactide (i.e. a dilactone, or a cyclic dimer of D-lactic acid), L-lactide (i.e. a dilactone, or a cyclic dimer of L-lactic acid), meso D,L-lactide (i.e. a cyclic dimer of D-, and L-lactic acid), and racemic D,L-lactide (racemic D,L-lactide comprises a 1/1 mixture of D-, and L-lactide).
• D-lactide i.e. a dilactone, or a cyclic dimer of D-lactic acid
• L-lactide i.e. a dilactone, or a cyclic dimer of L-lactic acid
• meso D,L-lactide i.e. a cycl
• the present biodegradable polymer composition may be used for various applications and should not be restricted to those the exemplarily disclosed herein.
• applications in the medical field such as e.g. for sutures, and drug release matrices, or in the agricultural industry are conceivable.
• the selected components can be first subjected to drying operations provided they do not have the required moisture yet, i.e. a max. of about 1 weight % of moisture.
• Moisture control is in fact critical for achieving the necessary conditions, namely to improve or increase the processability of the biopolymer material used for blending
• Mixing the above components is performed at room temperature by means of standard techniques like e.g. twin screw extrusion or ball milling until achieving a fully homogenized mass.
• the mixture can be further blended with additional polymer material like e.g. biodegradable polyester and/ or components like polymerization initiators and, optionally, inert mineral filler like a silicate or talc.
• additional polymer material like e.g. biodegradable polyester and/ or components like polymerization initiators and, optionally, inert mineral filler like a silicate or talc.
• Such a mixing operation is furthermore performed in a well controlled moisture atmosphere, preferably in a way that allows keeping moisture at a max. of ca 1 % weight or even lower if ever necessary.
• the homogenized blend is then further mixed by means of extrusion compounding like e.g. multiple screw extrusion, which is usually run at a temperature varying fro about 95° C to about 190° C depending on the zones of the mixing, for a period extending from about 2 minutes to about 5 minutes in most cases.
• extrusion compounding like e.g. multiple screw extrusion, which is usually run at a temperature varying fro about 95° C to about 190° C depending on the zones of the mixing, for a period extending from about 2 minutes to about 5 minutes in most cases.
• extruded mass is subsequently cooled using e.g. water bath or ice cold air current and eventually dried to the required humidity content.
• the extruded polymer composition can be transformed into pellets or balls or flakes or filaments depending on the necessity of its subsequent transformation into finished goods or articles; packaging and storage are done in such a way that the required humidity level is preserved.
• the extruded polymer composition can also be directly used for the subsequent transformation without any preliminary packaging or storage.
• a polymer composition of the present invention may be used for the production of various articles, such as e.g. molded articles and/or extruded articles.
• the term "molded article” (or “extruded article”) as used in the present invention comprises articles made according to a molding process (or an extrusion process).
• a "molded article” (or “extruded article”) can also be . part of another object, such as e.g. an insert in a container or a knife blade or fork insert in a corresponding handle.
• a molded article according to the present invention comprises a biodegradable composition, which biodegradable composition comprises between about 15 and about 55 % by weight of starch and 45 and about 75 % by weight of poly(lactic acid) polymer.
• the composition for the preparation of such molded articles can comprise in addition to the above-mentioned components mineral particles comprising at least one of magnesium and silicium.
• thermoform extrusion method examples are e.g. sheets for producing cups, plates and bottles and other objects, which could be outside of the food service industry.
• Injection molding, blown film extrusion, profile extrusion and thermoform extrusion are processes known to a skilled person and are described for example in Modern Plastics Encyclopedia, Published by McGraw-Hill, Inc. -mid-October 1991 edition.
• composition A Composition B
• Composition C Composition A
• PHA is a polymer created from Lactic Acid a three carbon organic acid: one terminal carbon atom is part of an acid or carboxyl group; the other terminal carbon atom is part of a methyl or hydrocarbon group; and a central carbon atom having an alcohol carbon group. Lactic acid exists in two optically active isometric forms. Poly-Lactic Acid is commercially available from different sources. The principal source being NatureWorks, Lie, a wholly own subsidiary of Cargill, Inc. a, US company. "Gluten” is corn gluten or wheat gluten. Both can be used in the formulations. Corn gluten is preferred because of its stability and consistency. Both products are available commercially from companies such as e.g. Sigma Aldrich, Penford Co., Archer Daniel Midlands (USA).
• Polymers is a Co-Polyester commercially available like e.g. Bio-Eastar from Eastman Chemical (USA) or Ecoflex from BASF (Germany).
• An injection molding formulation which comprises the following components:
• composition D Composition E
• Composition F Composition F
• Silicate 1 - 5 % 0 0 The selected components (humidity max. 1 weight %) are first blended in a rotating screw mixer at room temperature to afford a homogeneous powdered mass. That mass is then subjected to further mixing, heating and pressurizing in a twin screw extruder under the following conditions:
• the extruded plasticized polymer mass is cooled by means of a water bath, then converted into pellets using a strand pelletizer or an under water pelletizer and eventually dried under vacuum until reaching again a humidity of max. 1 weight % and then packed and stored until further processing. Drying of the pellets is done using a draying conveyor combining air blowing, vacuum and extraction; such a drying step is performed within milliseconds, in any case within a max. of 3 seconds after pellets move out of the water bath. Pellets as collected here above are then filled in a conventional injection molding device at a temperature of about 160 0 C and is injected into a mold at a temperature of about 20 °C in order to obtain an injection molded utensils or other shapes.
• thermoform extrusion formulation which comprises:
• composition A Composition B
• Composition C Composition A
• Example 2 The above-mentioned compounds are mixed and subjected to twin screw extrusion as defined in Example 2.
• the resulting polymer material is filled in a thermoform extrusion device at a temperature of 160 0 C and a sheet having a thickness between 0.1mm to 45mm is obtained which may be used for forming cups, plates or bottles.

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• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Biological Depolymerization Polymers (AREA)

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• 2005
  • 2005-12-02 US US11/293,517 patent/US20070129467A1/en not_active Abandoned
• 2006
  • 2006-05-16 EP EP06765428A patent/EP1966308A1/de not_active Withdrawn
  • 2006-05-16 WO PCT/IB2006/001281 patent/WO2007063361A1/en active Application Filing

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