DD299530A5 - DISTILLABLE THERMOPLASTIC FROM LACTIDEN - Google Patents

Abstract

The invention is directed to an environmentally biodegradable composition that can be used as a replacement for thermoplastic polymer compositions, with the characteristic that it contains a polymer of the formula: C CH3O {environment, biodegradable; Thermoplastic set, polymer; Plasticizers group; lactide; lactic acid oligomers; Laktidoligomere; Tensile strenght; Elongation at break; Tangent modulus}

Description

For this 11 pages drawings.

The present application and the priority of the claims are derived from the following US applications: The application entitled PLIABLE BIODEGRADABLE PACKAGING ING THERMOPLASTICS FROM LACTIDES (biodegradable, flexible packaging thermoplastics mjs Laktiden) with the serial number 07/229/896, filing date 8 August 1988; the application entitled BIODEGRADABLE REPLACEMENT OF CRYSTAL POLYSTYRENE (Biodegradable Substitution of Crystal Polystyren), Serial No. 07 / 229,939, filed August 8, 1988; the application entitled BLENDS OF POLYLACTIC ACID (blends of poly-lactic acid) of serial number 07 / 229,894, filed 8 August 1988; the application entitled DEGRADABLE IMPACT MODIFIED POLYLACTIDES (Degradable Impact Modified Polylactides), Serial No. 07 / 317,391, filed March 1, 1989; the application PLIABLE BIODEGRADABLE PACKAGING 'THERMOPLASTICS FROM LACTIDES (Lactides Biodegradable Packaging Thermoplastics) with the list of attorneys

Number DF 27G7-1, filing date31.July 1989; the application entitled BIODEGRADABLE REPLACEMENT OF CRYSTAL POLYSTYRENE (Biodegradable Substitution of Crystal Polystyron) having the Attorney Docket Number PF 2771-1, filing date 31June 1989; the application entitled BLENDS OF POLYLACTIC ACID (blends of poly-lactic acid) with the list of attorneys' number PF 2772-1, filing date 31 July 1989 and the application DEGRADABLE IMPACT MODIFIED POLYLACTIDES (Degradable, modified polylactides) with the attorney & listen number PF 2781-1, filing date July 31, 1989. All applications listed above have the Batteile Memorial Institute as proxy.

Field of application of the invention

In a first embodiment, the present invention relates to soft polymers of L-lactide, D-lactide, D, L-lactide and mixtures which are suitable for packaging purposes for which conventionally degradable plastics (eg polyethylene) are used , The first embodiment also relates to a process for producing flexible films and other packaging materials and their direct products. The invention is advantageously applicable to the production of a product having the characteristics of the conventional plastics and which is still biodegradable.

In a second embodiment, the invention discloses a material and a method of making the same, which is a compensating product which serves as a replacement for crystal polystyrene, sometimes known as orientable polystyrene or OPS. The material is a compensation product for OPS but consists of a polyester that biodegrades in the environment over a period of about one year. The material is a polyester, which consists of a polymerized lactic acid, prepared either from D-lactic acid or L-lactic acid and D, L-lactic acid The ratio of the two polymerized monomer units, the processing and certain auxiliary agents determine the precise physical properties necessary for the exact requirements of an OPS compensating product, therefore, with an approximate L-lactic acid / DL-lactic acid ratio of 90/10, the pulxmerized lactic acid (PLA) is a well-usable thermoplastic, clear, colorless and very Thus, it is well suited for the production of foils, foams and other thermoformed objects, disposable or disposable, and if it has served its purpose as packaging plastic, the PLA slowly degrades in the environment to harmless products when used in packaging This harmless elimination can contribute to the environment increasing problems of environmental pollution by plastics.

In a third Aueführungsart the invention relates to the mixture of conventional thermoplastics with poly-lactic acid. This produces novel, biodegradable thermoplastics. The environmentally degradable thermoplastics can be used advantageously in a wide variety of applications.

The third embodiment further relates to a process for producing flexible films and other packaging elements) as well as to the product made directly therefrom. The invention finds application in the manufacture of a product which has the characteristics of conventional plastics and is also degradable in the environment. A fourth embodiment of the invention relates to mixing compatible elastomers with polylactides. This produces impact-resistant, modified polyactides which can be advantageously used in a wide variety of applications, including those in which impact-modified polystyrene is used.

The fourth embodiment further relates to a method of manufacturing packaging means and to the product made directly therefrom. The invention is used in the manufacture of a product having the characteristics of common stoßrosistenter plastic and is still degradable in the environment.

Background of the invention

The huge quantities of discarded plastic packaging materials are a reason for the need for an environmentally biodegradable thermoplastic. In the United States, 53.7 billion pounds of plastic were sold in 1987, of which 12.7 billion pounds are listed as plastic for pre-packaging purposes. A significant amount of this plastic is thrown away and causes pollution by plastic, which is a stain in the Lendschaft and a threat to life in the sea. The estimates of seabird mortality are 1-2 million and sea animals 100000 per year.

Another problem with the removal of plastic packaging is the decreasing volume of landfills. It has been estimated that most of the largest cities will have used up the available landfills for solid waste disposal in the early 1990s. Plastics contain about 3% by mass and 6% by volume solid waste. Another disadvantage of conventional plastics is that they are ultimately derived from petroleum, which makes plastics dependent on the uncertainties of foreign crude oil imports. A better source material would have to be gained from renewable domestic resources.

However, there are good reasons for using plastic packaging material. They deliver attractive aesthetic qualities in the form of attractive packaging that can be quickly produced and filled with products. The packages retain their cleanliness, storage stability and desirable properties such as transparency for the purpose of controlling the contents. These packages are known for their low production costs and chemical stability. However, this stability results in a very long life of plastics, so that when their one-time use is completed, thrown-away packages remain unpredictably long in the environment.

Polymers and copolymers of lactic acid have been known for some time to be the only materials that are biodegradable, biocompatible and thermoplastic. These polymers are highly engineered thermoplastics that are 100% biodegradable in an animal's body through hydrolysis over a period of several months to a year. In a humid environment, after several weeks of degradation begins, and they disappear about a year, if you leave them on or in the soil or seawater. The degradation products are lactic acid, carbon dioxide and water, all of which are harmless. In practice, lactic acid is converted into its cyclic dimer lactide, which becomes the monomer for the polymerization. Lactic acid can potentially be obtained from cheap starting materials, e.g. Corn starch, corn syrup, fermentation or from petrochemical sources, e.g. B. ethylene. Lactide monomer can be readily converted to resin by catalyzed lard polymerization, a common practice well known to plastics manufacturers. Carrying out the polymerization of an intermediate homomer enables mobility in the resin composition. The molecular weight can be easily controlled. For introducing specific properties, the compositions can be varied.

Homopolymers and copolymers of various lyclic esters, e.g. B. Glycolide, Lactide and the lectins have been set forth in numerous patents and scientific publications. Previous patents have described processes for the polymerization of lactic acid, laclide, or both, but did not yield polymers of high molecular weight and good physical properties, and the polymeric products were often sticky, adherent materials without good physical properties. See Example US Pat. Nos. 1,995,970, 2,362,611 and 2,683,136. The patent to Lowe, U.S. Patent 2,368,162, first cites the use of pure glycolide and lactide to provide polymers and copolymers "; of high molecular weight lactide. Lactide is the dilactone of lactic acid and is an internal ester of lactic acid. When lactide is formed, the by-produced water is eliminated, thereby allowing the lactide to be subsequently polymerized by ring cleavage to linear high molecular weight polyester without lengthy condensation procedures. The copolymerization of lactide and glycolide gave toughness and improved thermoplastic processability compared to the homopolymers. Using the intermediate lactide to make PLA gave polymers and copolymers with excellent physical properties. Copolymers of lactide and glycolide are given in the patent to Lowe, which are tough, clear, kaltziehbar, stretchable and which can be at 210 ⁰ C to form unsupported films. In similar publications in the patent and other literature, processes have been developed for the polymerization and copolymerization of lactide to produce strong, crystalline, orientable rigid polymers from which have been produced fibers and prosthetic devices that were biodegradable and biocompatible, and sometimes absorbable were designated. The polymers slowly disappeared by hydrolysis. See, for example, U.S. Patent Nos. 2,703,316, 2,758,987, 3,297,033, 4,363,158, 3,531,561, 3,620,218, 3,636,956, 736,646, 3,797,499, 3,839,297, 3,982,543. 4,243,775, 4,438,253, 4,496,446, European Patent Application 0146398, International Patent Application WO 80/00533 and Laid-Open Patent 2,118,127.

Other patents report the use of these polymers as rigid surgical elements for biomedical holders, screws, nails, pins, and bone plugs. See, for example, U.S. Patent Nos. 3,739,773, 4,060,089 and 4,279,249. Controlled release devices of mixtures of bioactive substances with the polymers and copolymers of lactide and / or glycolide have been set forth. See, for example, U.S. Patent Nos. 3,773,919, 3,887,699, 4,273,920, 4,419,340, 4,471,077, 4,478,384, 4,728,721, RG Sinclair, Environmental Science & Technology, 7 (10), 955 (1973). , RG Sinclair, Proceedings, 5th International Symposium on Controlled Release of Bioactive Materials, 5.12 and 8.2., University of Akron Press, 1978. These uses of lactide polymers and copolymers required tough or glassy materials that could be ground and that lacked physical properties for a clear use as thermoplastic packaging materials.

The prior art has cited the use of lactide copolymers for clear packaging purposes. Thus, the aforementioned Lowe patent mentions clear, unsupported films of a copolymer of lactide and glycolide. US Pat. No. 2,703,316 describes lactide polymers as film formers which are tough and orientable. It was cited as "wrapping fabric" which was tough, flexible and strong, brittle or pliable, but in order to obtain flexibility, the polylactide must be moistened with a volatile solvent otherwise stiff and brittle polymers will be obtained indicated about 12O ⁰ C. L-Laktidmonomer melts at 95 ⁰ C, and D, L-lactide melt at 128 ⁰ C. this is an example of the previously known prior art, which is of special modifications Laktidpolymeren to a flexibility to For example, US Patent 3,021,309 discloses the copolymerization of lactides with delta-valerolactone and caprolactone to modify lactide polymers and to obtain tough, white crystalline solids. Soft, solid copolymer compositions are used only with the copolymers of caprolactone and caprolactone 2,4-dimethyl-4-methoxy-methyl-5-hydroxypentanoic acid lactone, but not mentioned with lactide compositions, U.S. Patent 3,284,417 to the preparation of polyesters useful as plasticizers and intermediates for the production of elastomers and foams. This patent excludes lactides and uses compositions based on 7- to 9-membered ring lactones, e.g. Epsilon-caprolactone to obtain the desired intermediates. No tensile strength, modulus or percent elongation values are given. US Pat. No. 3,237,033 deals with the use of glycolide and glycolide lactide copolymers for the preparation of opaque materials which can be oriented to fibers suitable for medical suture. It is noted that "plasticizers affect the crystallinity but are useful for sponges and films." It is clearly evident from these data that lactide polymers and copolymers are stiff if not plasticized, as is U.S. Patent 3,736,646 after Lactide glycolide copolymers are plasticized by the use of solvents, e.g., methylene chloride, xylene, or toluene., U.S. Patent 3,797,499, cites L-lactide and D, L-lactide, for greater flexibility in stretchable suture absorbent fibers These fibers have strengths in excess of 50,000 psi with percent elongations of about 20% The moduli are about one million psi These are still very stiff compositions compared to the highly flexible packaging material compositions, which is reflected in their use as sutures U.S. Patent 3,844,987 teaches the use of graft copolymers and biologic mixtures sch degradable polymers with naturally occurring biodegradable products set forth, for example, cellulosic materials, soybean powder, rice husks and brewer's yeast, for production items, eg. As a container for receiving a medium to seed or seedlings to germinate and pull. These articles are not suitable for packaging purposes.

U.S. Patent 4,620,993 discloses a biodegradable disposable bag composition consisting of polymers of 3-hydroxybutyrate and 3-hydroxybutyrate / 3-hydroxyvalerate copolymer. Lactic acid is comparatively 2-hydroxypropanoic acid. U.S. Patent 3,982,543 treats the use of volatile solvents as plasticizers in lactide copolymers to achieve flexibility. U.S. Patent Nos. 4,045,418 and 4,057,537 relate to the copolymerization of caprolactone with lactides, either L-lactide or D, L-lactide, to provide flexibility. U.S. Patent No. 4,052,988 is directed to the use of poly (p-dioxanone) to provide improved knot tying and knot security for absorbable suture. U.S. Patent Nos. 4,387,769 and 4,526,695 disclose the use of lactide and glycolide polymers and copolymers which are deformable, but only at elevated temperatures. European Patent 0108933 uses a modification of glycolide copolymers with polyethylene glycol to obtain triblock polymers which are used as sutures. As already mentioned, there is a strong consensus that you einf. Likability of Laktidpolymeren only obtained by plasticizers, which are volatile and consist of volatile solvents or other comonomer substances.

Copolymers of L Lactld and D, L-Lak; id are known in the prior art, but evidence indicates that flexibility is no related physical property. US Pat. No. 2,758,987 treats homopolymers, either L- or DL-lacticl, which are melt-pressibly described as being too clear, solid, orientable films. The properties of poly-L-lactide are given as follows: tensile strength 29000psi, elongation 23%, modulus 710000psl. The properties of Poly-DL-lactide were: tensile strength 26000 psi, elongation 48% and a modulus of 260,000 psi. Copolymers of L and D, L-lactide, that is, copolymers of L and D, L-lactic acid, are given only for a 60/50 mass deletion. Only properties of the stickiness point are mentioned (example 3). The claims set out that an antipodal (optically active, eg, L-lactide) monomer is preferred for producing higher strength. The homopolymers of L-lactide and D, L-lactide, and the L / D, L-lactide copolymers having a mass ratio of 75 / 25.60 / 50 and 25/75 are exemplified in U.S. Patent No. 2,951,828, which is incorporated herein by reference treated the bead polymerization of Alphp-Hydroxykarbonsäure. The copolymers have softening points of 110-135 ° C. Are given no further physical property values in terms of rigidity and flexibility, except physical properties that affect bead size and softening points in the range of 110 to 135 ⁰ C. The L-lactide / DL-lactide copolymers having a mass ratio of 95 / 5,92,5 / 7,5,90 / 10 and 85/15 are given in U.S. Patents 3,636,956 and 3,797,499. They are considered to be filaments of drawn fibers and have tensile strengths in excess of 50,000 psi, moduli of about one million, and elongation values of about 20%. To achieve flexibility, the same plasticizers are used as in US Pat. No. 3,636,956. A snow-white, distinctive crystalline polymer is disclosed in Laid-Open Specification 2,118,127 for a 90/10 L-lactide / D, L-lactide copolymer. No physical properties are mentioned for this copolymer. The patent mentions the use for surgical elements. U.S. Patent Nos. 3,297,033, 3,463,158, 3,531,561, 3,636,956, 3,736,646, 3,739,773, and 3,797,499 all call lactide polymers and copolymers the highly crystalline orientable polymers suitable for fibers and suture. These figures relate to the use of highly crystalline materials which are oriented by stretching and stress relief to achieve tensile strengths and moduli typically greater than 50,000 psi and 1,000,000 psi, respectively. Although moldability is mentioned in a variety of articles, the physical properties of unoriented extrudates and shapes are not mentioned. For example, U.S. Patent No. 3,636,956 includes the preparation of an L-lactide / DL lactide having a weight ratio of 90/10, and cited oriented fibers. However, in this discussion, the use of pure L-lactide monomer for higher crystallinity and strength of the drawn fibers is preferred. US Pat. No. 3,797,499 deals with the copolymerization of L-lactide / D, L-lactide with a mass ratio of 95/5 (Example V), but filaments are produced from this material. In column 5, line 1, Schneider informs about enhanced properties in the range proposed in the present invention. Plasticizers, for example glyceryl triacetate, ethyl benzoate and diethyl phthalate are used.

U.S. Patent Nos. 3,736,646, 3,773,919, 3,887,699, 4,273,920, 4,471,077, and 4,578,384 disclose the use of lactide polymers and copolymers as a sustained-release matrix of medicaments that is biodegradable and biocompatible , Again, physical properties of the polymers from conventional thermoforming processes, e.g. B. film extrusion or molding not specified.

Of particular interest is U.S. Patent 4,719,246, which teaches the mixture of homopolymers of I-lactide, D-lactide, polymers or mixtures thereof and copolymers of L-lactide or D-lactide with at least one non-lactic comonomer. The mixture is intended to produce compositions having interacting segments of poly (L-lactide) and poly (D-lactide).

Canadian Patent 808,731 cites copolymers of L and D, L-lactides in which a Group II divalent metal is part of the structure. The 90/10 LVD ^ lactide copolymer (Example 2) and the L-lactide homopolymer were described as "suitable for films and fibers." The 90/10 copolymer is described as a snow-white copolymer, and the L-lactide homopolymer can become transparent films (The more crystalline polymer must be the opaque or snow-white material which is the homopolymer.) The patent discloses "the fact that it is believed that the novel polylactides of the invention contain the metal component of the catalyst in the form of a lactate is ". Next: The polylactides find application in the production of films and fibers by means of conventional production processes for thermoplastic resin. No physical property values for the strength and flexibility of Γ "η are given.

Canadian Patent 863,673 discloses compositions of L-lactide and D, L-lactide copolymers in the ratios 97 / 3.95 / 5,92,5 / 7,5,90 / 10 and 85/15 of L- / D, L Lactide indicated. They were all characterized as extensible filaments for surgical purposes. The tensile strength, about 100,000 psi, was high, the elongation approximately 20%, and plasticizers were mentioned for the purpose of achieving flexibility. D.L-lactide compositions below 15% by mass are fixed in the claims. In Canadian Patent 923,245, the copolymers of L- and D, L-lactide are treated (Example 15). The 90/10 copolymer is described as a snow white polylactide. It is noted that the polylactides made by the methods of the patent are used in the production of films and fibers made according to conventional thermoplastic resin fabrication processes.

US Pat. No. 4,719,246 discloses the use of simple mixtures of poly-L and poly (D-lactide) polymers and mixtures thereof referred to as poly (S-lactide) and poly (R-lactide) and copolymers of L-lactide or D-lactide treated with at least one non-lactic comonomer. The examples all represent physical mixtures. The specific properties of "caking" are derived from racemic compound formation (see "Stereochemistry of Carbon Compounds", E.L. Eliel, McGraw-Hill, 1962, page 45). Racemic compounds consist of caged enantiomers, that is, the D and L forms (or R and S) are joined together by polar forces. This can lead to a decrease in crystalline melting points, depending on whether the D to D (or L to L x) forces are less or greater than the D to L forces. To increase the effect, homopolymers or large chain lengths of D and L are required for polymer-racemic compounds (and set forth in U.S. Patent 4,719,246, column 4, line 48). The great symmetry or regularity of this structure enables compression or caking by very regular polar forces either by being the same or mirror images. This leads to a considerable crystallinity. The technique of racemic compounds has a long history dating back to classical chemistry. U.S. Patent 4,661,530 discloses blends of a poly (L-lactic acid) and / or poly (D, L-lactidacid (lactic acid)) with sequestered polyosterurethane. or Polyetharurethanen treated. Biodegradable materials are produced which are useful for synthetic replacement of biological tissues and organs in reconstructive surgery. Now it is demonstrated in the prior art that lactide polymers for flexible, highly elastic

Compositions using lactide monomers, lactic acid or oligomers of lactic acid or lactides as plasticizers can be used. None of the earlier compositions are suitable for the defined packaging need of the thermoplastic polymer producing industry.

It will be appreciated by those skilled in the art that the doubling of the properties of one thermoplastic by another is not predictable. As a result, there are exact requirements for Krlstall polystyrene or OPS for satisfactory use of polystyrene, which has evolved over many years to meet the specification of OPS grades for manufacture and end use.

Brief description of the invention

The general teachings of the invention and the first embodiment are that L-lactide, D-lactide and DL-lactide homopolymers and copolymers of their mixtures plasticized with lactide monomer (s), lactic acid or oligomers of lactide or lactic acid, be used as a highly useful thermoplastics, which may have similar properties as the usual, non-degradable in the environment plastic (eg the properties of polyethylene, etc.). This composition has the formula:

CH ^

f G -C-O

and is intimately plasticized with a plasticizer selected from the group consisting of lactide, lactic acid, oligomers of lactic acid and mixtures thereof. The oligomers of lactic acid are further preferably represented by the formula II wherein m is an integer: 2 <m <75. However, m is preferably 2 <m · s. The plasticizer preferably contains 2 to 60 mass% of polymer. The polymers can be obtained from lactide monomers selected from a group consisting of L-lactide, D-lactide, meso-D, L-lactide and mixtures thereof. Preferably, η is 150 pounds η 20000.

- o

Lactide monomer may be present in a proportion of from 5% to 40% by weight of the polymer, while lactide oligomer or lactic acid and its oligomers may be present in a proportion of 2-60% by weight. This composition allows many desirable features of the polyethylene, e.g. Flexibility, transparency and tenacity. Furthermore, a method for producing the biodegradable composition is proposed. The method includes the steps of mixing, heating and melting one or more lactide monomers and catalyst; Polymerizing the monomers of the solution to produce a polymer at a sufficiently low temperature such that the polymerization reaction can be stopped prior to completion of the polymerization, monitoring the monomer content and stopping the reaction before completion of the polymerization at a monomer level determined by the control unreacted monomer is included together with the polymer. Also, a method is proposed for producing a plasticized polymer of poly-lactic acid consisting of mixing, heating and melting one or more lactide monomers and a catalyst, polymerizing the monomers of the solution to produce a polymer without interrupting the reaction and incorporating a plasticizer in the Polymers, wherein the plasticizer is selected from the group consisting of D-lactide, L-lactide, meso-D, L-lactide, lactic acid, oligomers of lactic acid and mixtures thereof.

A second embodiment of the invention includes a process for preparing an environmentally biodegradable composition and an environmentally biodegradable composition which can be used as a substitute for polystyrene consisting of polylactic acid structural units of the formula I in which η is a integer between 75 and 10,000 and the alpha-carbon is a mixture of L and D configurations with an overweight of either D or L moieties, wherein the polymer is from L-lactide or D-lactate at 85 to 95 15 to 5 parts by weight, the unoriented polymer having a tensile strength of at least 5000 psi and a tangent modulus of at least 200,000 psi and dispersing plasticizer in the amount of 0.1-5 mass%. In a third embodiment of the invention, the process of preparing an environmentally degradable composition and an environmentally degradable composition comprising mixtures of a physical mixture of poly-lactic acid and one or more of a group of selected polymers consisting of a polymer of Ethylene terephthalate, a polymer or copolymer of styrene, ethylene, propylene, vinyl chloride, vinyl acetate, alkyl methacrylate, alkyl acrylate and their physical mixtures.

In a fourth embodiment, a process is described for: producing an environmentally degradable composition, and presenting an environmentally degradable composition consisting of blends of a physical blend of poly-lactic acid and blend compatible elastomers having improved impact resistance for the invention mixed composition. Such an elastomer may be, for example, a Hytrel ™, a segmented polyester having a block copolymer of hard crystalline segments of polybutylene terephthalate and soft long chain segments of polyether glycol. An example is known as segmented polyester under the name Hytrel ™ 4056 (DuPont). '

Brief description of the pictures Figure 1 is a graph of the relationship between percent lactide content in the composition as Plasticizer and tensile strength. Figure 2 is a graphic representation de; Relationship between the percentage of lactide in the composition as Plasticizer and the modulus of elasticity. Figure 3 is a graph of the relationship between percent oligomer content in the composition

plasticizer and tensile strength, where curve A is for a 90/10 copolymer and curve B is for a 92.5 / 7.5 copolymer.

Figure 4 is a graphic representation of the relationship between percent oligomer content in the composition

plasticizer and Young's modulus, where curve A is for a 90/10 copolymer and curve B is for a 92.5 / 7.5 copolymer.

Figure 5 illustrates the Differential Scanning Calorimetry (DSC) diagram for de-stressed 90/10 L '/ D ^ lactide copolymer of Example 5B. Figure 6 illustrates the DSC of the material de. "Example 5B after remaining for 100 minutes at 7O ⁰ C. Figure 7 illustrates the DSC of the material of Example 5B after exposure at 185 ^° F overnight. Figure 8 illustrates the DSC of the material of Example 5B blended with 5% potassium lactate. Figure 9 compares the melt viscosity as a function of the polynuclear shear perturbations of polystyrene and that according to Example 8 B produced lactide polymer. Figure 10 illustrates the DSC for a copolymer of Example 8B. Figure 11 illustrates the DSC for the L-lactide homopolymer that was added to the copolymer of Example 8β. Figure 12 illustrates the DSC for the blended composition of Example 23 from the copolymer of the Example

8B and a homopolymer of L-lactide.

Figure 13 illustrates a differential scanning calorimetry (DSC) plot of 90/10 L-ZD.L lactide copolymer.

mixed with 5Ma .-% polystyrene.

Detailed Description of the Invention In the preferred embodiment, first generic embodiment

The biodegradable compositions set forth herein are fully biodegradable to environmentally acceptable and compatible materials. The breakdown intermediates lactic acid and short chain oligomers of lactide or lactic acid are widely distributed, naturally occurring substances that are easily metabolized by many organisms. Their natural end-products are carbon dioxide and water. Considered equivalents of this composition, for example, those containing minor proportions of other substances, fillers or cosolvents may also be completely biodegradable by proper choice of the substances. The compositions herein provide environmentally degradable materials because their physical decomposition and degradation are much faster and more complete than with the conventional non-degradable plastics they replace. Further, since all or a major portion of the composition is poly-lactic acid and / or lactic acid or lactic acid-derived lactide or oligomer, there is no residue or only a minor portion of a more slowly degradable residue. This residue has a larger surface area than the bulk product and an expected greater rate of degradation.

The general application of the invention is reflected in the first and general embodiment of the invention. The homopolymers of D-lactide, L-lactide, D, L-lactide and copolymers of D-lactide, L-lactide; D-lactide, D, L-lactide; L-lactide, D, L-lactide and D-lactide, L-lactide and D, L-lactate d produce all materials useful in the invention when combined with lactide monomers, lactic acid, oligomers of lactide, oligomers, of Lactic acid and its mixtures are plasticized. The plasticizer can be prepared by stopping the reaction before the polymerization is complete. Alternatively, one may additionally add plasticizer to the polymer consisting of lactide monomers (D-lactide, L-lactide, D, L-lactide or mixtures thereof), lactic acid, oligomers of lactide or oligomers of lactic acid and mixtures thereof. The polymer is defined by the formula:

OH ₃ ρ

C -

wherein η is the degree of polymerisation (number of repeating structural units) and plasticized with a plasticizer resulting from incomplete polymerization of the monomers used to prepare the polymer. The more intimately the plasticizer is integrated into the polymer, the better its properties. If desired, additional monomer or oligomer can be added to any residual monomer or oligomer that remains in the composition. The oligomers of lactic acid for a plasticizer are defined by formula II wherein my integer is 2 S m s 75, but the preferred range is:

- C - O jm

In order to obtain flexible thermoplastics, the proportions of L-lactide, D-lactide and D, L-lactide are not considered to be critical. The proportions of L-lactide, D-lactide, and D, L-lactide can vary over a broad mass ratio to form a homopolymer or copolymer. The lactide monomers used according to the invention are commercially available, so that neither the monomer reactant per se nor the process, once prepared, form part of the invention.

D-lactide is a dilactone or cyclic dimer of D-lactic acid. Analogously, L-lactide is a cyclic dimer of L-lactic acid. Meso-D, L-lactide is a cyclic dimer of the D and L lactoacids. Racemic D, L-lactide contains a mixture of and L-lactate! D. When used alone, the term "D.L-lactide * Msso-D.L-lactide or racemic D.L-lactide" should be used. One of the methods of producing a lactide described in the literature is to dehydrate lactic acid under high vacuum. The product is distilled at high temperature and low pressure. Laklide and its preparation are treated by W.H. Carothers, G.L. Dorough and M.J. Johnson (J. Am. Chem. Soc., 64, 761-762 (1932)); J. Gay-Lussac and J. Pelouse (Ann. 7.43 [1833]); CA. Bischoff and P.Waiden (Chem. Ber 26, 263 (1903); Ann. 279, 171 [1984] and Heinrich Byk (Ger. Pat. 267, 826 (1912) in Chem. Abstr., 8, 654, 204 [1914]).

The optically active acids can be obtained by direct fermentation of almost all non-toxic carbohydrate products, by-products or waste using numerous bacterial strains of the genus Lactobacillus, e.g. B. Lactobacillus delbrueckll, L. tallvarlus, L. easel, etc. are produced. One can also optically active acids by the dissolution of the racemic mixture by zinc ammonium salt or the salt of alkaloids, z. As morphine obtained. L-lactide is a white powder having a molecular weight of 144. When an impure commercial product is used in the context of the present invention, it must preferably be purified by recrystallization from anhydrous methylicobutyl ketone. The snow-white crystals of the lactide melt at 96-98 ⁰ C.

DL-lactic acid, which is used for the production of D, L-lactide, is available commercially. The DL-lactic acid can be produced synthetically by hydrolysis of lactonitrile (acetaldehyde cyanohydrin) or by direct fermentation of almost all non-toxic carbohydrate products, by-products or waste using numerous bacterial strains of the genus Lactobacillus. D, L-lactide is a white powder with a molecular weight of 144. If an impure commercial product is used in connection with the invention, it is recommended to purify it by recrystallization from anhydrous methyl isobutyl ketone. Such a commercial product containing a pulpy semi-solid melting at 90-13O < ⁰ > C was recrystallized from methyl isobutyl ketone and decolorized with charcoal. After three such recrystallizations, the product was drum dried in vacuo with nitrogen cycling for 8 to 24 hours at room temperature. The resulting snow-white crystals contain a D, L-lactide mixture, which melts at 115-128 ⁰ C. In preparing the compositions according to the invention, it is preferred to conduct the reaction in the liquid phase in a closed, evacuated reactor in the presence of a stannous ester of a carboxylic acid containing up to 18 carbon atoms. However, the compositions may also be applied at atmospheric pressure in inert gas, e.g. As nitrogen, polymerization system described. When the polymerization is carried out in the presence of oxygen or air, some discoloration occurs with a consequent decrease in molecular weight and tensile strength. The process can be carried out at temperatures at which the polymerization proceeds sluggishly in its later stages so that residual monomer is included in the viscose polymer melt. For this purpose, the preferred temperatures are generally between the melting point of pure L-lactide and pure D, L-lactide or 95-197 ⁰ C. While not in any way the scope of the invention is to be limited, it is held up for possible in that below about 129 ^° C. the following occurs:

1. The lactide monomer mixture of L and D, L-lactide monomers melts and forms a eutectic mixture which melts to a mobile medium, that is, to an intimate solution of one, two or three monomers.

2. The liquid melt is polymerized using a catalyst to form an increasingly viscous solution, and possibly unreacted monomer is held together with the polymer in solution rather than in a clear heterogeneous phase. The monomer can no longer react because the reaction is extremely diffusion-controlled and can not come into contact with the low concentration of active end groups of the polymer.

3. The polymerization ceases or slows considerably so that at room temperature the mixture of monomers and polymers is a solid solution which softens the composition, imparting to it purity and flexibility.

4. The catalyst has a deactivating effect, so that the subsequent melt processing does not initiate the polymerization again.

5. The plasticized composition is very stable because the residual monomer has a very high boiling point, e.g. For example, the boiling point of lactide at 142 ⁰ C is at 8Torr and is closely connected with its open-chain tautomeric polylactide.

As an alternative, the method may be performed at any temperature between the melting point of L-lactide and 200 ⁰ G, and lactic acid or L-lactide is subsequently melt or in the polymer as a further process stage solvent-mixed. Temperatures above 200 ^° C. are not recommended since the copolymer tends to decompose. In general, increasing the temperature within the range of 95-200 ⁰ C increases the polymerization rate. By heating a mixture of L-lactide and D, L-lactide to a temperature between about 110 ° C and 16O ⁰ C has achieved good results.

The catalysts used in this invention are tin esters of carboxylic acids containing up to 18 carbon atoms. Examples of such acids are formic, propontic, butyric, valeric, n-caproic, n-caprylic, pelargonic, n-capric, lauric, myristic, palmitic, stearic and benzoic acids. Good results have been achieved with tin (II) acetate and tin (II) caprylate. The catalyst is used in normal amounts. In general, a catalyst concentration in the range of about 0.001 to about 2% by weight based on total weight of L-lactide and D, L-lactide is suitable. A catalyst concentration in the range of about 0.01 to about 1.0 mass% is preferred. Good results have been achieved when the catalyst concentration ranges from about 0.02 to about 0.5 mass%. In a specific case, the exact amount of catalyst depends to a large extent on the catalyst used and the operating variables including time and temperature. Professionals can easily determine the exact conditions.

The reaction time of the polymerization step per se is determined by the other reaction variables including reaction time, the particular catalyst, the amount of catalyst and whether a liquid binder is used. The reaction time can vary from minutes to hours or days, depending on the series of applied conditions. The heating of the monomer mixture is continued until the desired degree of polymerization is determined. The Polymerlsationsgrod can be determined by analysis of the residual monomers. As already discussed, one can choose the reaction temperature to increase the incorporation of monomers and obtain plasticized compositions coming directly from the polymerization reactor. The reaction can be stopped at such a time when the composition has reached the conversion of monomers to polymers required to achieve the desired plasticization. In the preferred embodiment of the invention, approximately 2-30% of lactide remains unreacted, depending on the plasticization achieved.

In general, preference is given to carrying out the polymerization without Fremdbestandteüe, the active hydrogen

since the presence of such impurities leads to an end activation of the catalyst and / or an increase in the

Induction time can lead. It is also preferable to conduct the polymerization under substantially anhydrous conditions Conditions. The copolymers of the invention may be prepared by bulk polymerization, suspension polymerization or solution polymerization

produce. The polymerization can be carried out in the presence of an inert, normally liquid organic binder, e.g. As aromatic hydrocarbons, such as benzene, toluene, xylene, ethylbenzene u. 8th.; oxygenated organic compounds, eg. Anisole, the dimethyl and diethyl esters of ethylene glycol; normal liquid-gelled

Hydrocarbons including open-chain, cyclic and alkyl-substituted cyclic saturated hydrocarbons, e.g. Hexane, Heptane, cyclohexane, alkylcyclohexane, dehydronaphthalene and the like. The polymerization process can be carried out batchwise, semicontinuously or conventionally. For the production of Lactide monomer reactants and the catalyst for subsequent polymerization can be prepared in accordance with

add to the known polymerization techniques in each mixing sequence. Accordingly, one can add to the catalyst all monomeric reactants. Thereafter, the catalyst-containing monomer may be mixed with the other monomer. Alternatively, the monomeric reactants may be mixed together. The catalyst can then the

Reactant mixture can be added. If desired, the catalyst may be in an inert, usually liquid

Dissolve or suspend organic binder. If desired, the monomeric reactants, either as a solution or suspension in an inert organic binder, the catalyst, the catalyst solution or the

Add catalyst suspension. In addition, one can still the catalyst and the monomeric reactants simultaneously in

give a reactor. The reactor may be equipped with a conventional heat exchanger and / or a mixing device. The reactor may be any equipment normally used in the art for making polymers. For example, a suitable reactor is one made of stainless steel.

The biodegradable biodegradable compositions according to the invention find, depending on the L-lactide, D-Lactide, Meso-D, L-lactide ratios Applications in manufacturing articles such as films, fibers, moldings and laminates,

which are manufactured according to conventional manufacturing processes. These manufactured articles are for non-medical

Fields of application provided, that is outside the body, where they are the usual, non-degradable in the environment plastic

can replace.

For example, filaments are produced by melt extrusion of the copolymer through a spinneret. Slides are going through Casting solutions and their subsequent removal from biodegradable compositions produced by

one presses solid, biodegradable compositions in a hydraulic press after heating the plates or by extruding them through a tool.

For the production of moldings from the copolymers of the invention can be various techniques including a

apply slow or very rapid cooling.

Crosslinking can be achieved by mixing the composition with free-radical initiators, e.g. B. Cumenhydroxid and

reach subsequent forms at elevated temperatures. This can increase the heat and solvent resistance. Curing can also be achieved by blending the copolymers with multifunctional compounds, e.g. B.

Polyalcohols and molding or thermoforming under heat and vacuum. Anpolymerized extruder reactions for the purpose

Hardening of the polyesters are a clear method for crosslinking and chain extension of the copolymers.

In the manufacture of moldings, a filler may be incorporated into the compositions prior to curing. On Filler has the task to modify the properties of a molded part including hardness, strength, Temperature resistance, etc. Known fillers include aluminum powder, powdered calcium carbonate, silica, kaolinite

(Kaolin), magnesium silicate and the like. Of particular advantage is starch, which mixes well with the compositions, and a mixture is obtained which is completely biodegradable in the environment. Further property modifications can be made by melt blending the compositions with other polymers and copolymers of lactides, glycolides and

Reach caprolactone. The compositions according to the invention can be used to produce reinforced laminates according to the known Use procedure. In general, laminates of fibrous materials or by assembling a variety of Material webs made to form a matrix, which can be solidified into a unitary structure by a

flowable molten precursor or by a composition of the fibrous material and curing in one

Mold or in a hydraulic press for the production of the polymer. Fibers used to form the matrix

include natural and synthetic fibers, e.g. B. cellulose from wood, cotton, linen, hemp u. Ä., Glass, Nylon,

Cellulose acetate and the like The compositions of the invention and their preparation are further exemplified by the following specific examples

illustrated.

example 1 L-lactide / racemic D, L-lactide, 80/20

160 grams of lactide and 40 grams of racemic DL-lactide, both of high purity (Purac Inc., recrystallized 3 times), were placed in a 500 ml round bottom flask and purged with dry nitrogen overnight. 10 ml of zinc dioxide were dissolved in 60 ml of anhydrous toluene, and 10 ml of the solvent are distilled in a Dean-Stark receiver to achieve dryness of this catalyst solution by azeotropic distillation. From the 10ml tin (II) octoate In 50ml dry toluene is taken by syringe a quantity of 0.20ml and injected into the lactides in the reaction flask. The nitrogen purge is carried out continuously via a syringe needle connection which is introduced into the reaction flask through a rubber septum. About a connected with a gas pipe piece pipe venting takes place. The nitrogen flow is at 1-3 bubbles. ; o second held. The flask was heated in an oil bath maintained at 123-127 ⁰ C. During the first stage of heating, the lactides melt and are thoroughly mixed by vortexing. After that, the products become quite viscous. After heating for 20 hours, the flask with the colorless, transparent products is taken out of the heating bath, cooled, the flask broken and shocked with liquid nitrogen to remove glass from the product. The copolymer was molded in a heated hydraulic press. A compression to 5-1 omn thick films was possible at a pressure of 20,000 lb at 17O ⁰ C in a time of 2 min. The slides were on hers

Strength properties are tested on an Instron tester, and the results are summarized in Table 1. To test the impact strength, V "inch thick specimens were compression molded. A thermogravimetric analysis (TGA) of the product was carried out and the mass loss after heating the sample to 160 ° C in 4min and maintaining the temperature at 160 ⁰ C for 6OmIn noted. The mass loss of the sample was 19.5% and was almost complete in 60 minutes. The loss of mass is accompanied by a loss of lactide monomers. The results of the differential Scanningkalorimetrle (DSC) showed that the composition has a Wärmeverbrr.uch starting at 110 ⁰ C, which becomes more pronounced as the temperature increases to 20O ⁰ C. No melting point was observed. The test specimens were de-energized at 185 ⁰ C overnight and retested. They remained transparent, colorless and flexible. Samples of the copolymer could be re-molded 6x, without discoloration or obvious loss of strength. Despite repeated deformation, thin films were clear, transparent, colorless and very flexible.

Table 1: Properties of copolymers ^(>) of lactide and D, L-lactide in plastification by lactide

example 1 8th 2 8th 3 10 * 7.9 number 3.5 Film thickness, mil 3.9 1.7 - Tensile strength, 100 psi 28 806 - ASTM 0.74 - 289 Strain, % 1.20 - 100% modulus, 1000 psi 36.6 - 0.4 200% modulus, 1000 psi 341 Tangent module, 1000 psi 0.63 - 97.5 Impact resistance after 640 281 2.7 Izod, ft-Ib / inch ^iw 270 118 _Mw , 1000's 19.5 27.8 M ", 1000's Restlsktid ^lcl%

(a) Mass L-racemic D.L Laklid 80/20

(b) V (ZoII, notched specimens

(cj loss of mass at 1 BO'C by Taothermleche TGA

Example 2

1.84 kg of L-lactide, 0.46 kg of racemic D, L-lactide and 2.3 ml of tin (II) octate solution were added analogously to Example 1 to a 3-liter round bottom flask. The mixture was purged 3 hours, then heated isothermally in a 125 ⁰ C oil bath with argon. The mixture melts, has been thoroughly mixed by vortexing to form a homogeneous, transparent, colorless medium whose viscosity substantially increases after several hours. After 64 hours, the flask was removed from the heating bath, cooled and the glass removed from the clear, transparent, solid product. The gummy composition was sliced and ground to Vs inch or smaller in a mill with dry rice. The millbase was dried in an air circulation oven at 100 ° F for several hours, then vacuum dried overnight at ambient temperature. Molded films were made as in Example 1 and tested for strength properties and mass loss by TGA as shown in Table 1.

Example 3

79.98 g of lactide, 20.04 g of racemic D, L-lactate and 0.20 ml of tin (II) octane solution were added analogously to Example 1 to a 250.ml round bottom flask. The flask was purged of nitrogen via inlets and outlets and heated in a 125 ° C oil bath. The mixture melted to a colorless and liquid medium which was thoroughly mixed by vortexing the flask. After 2 hours, the oil bath temperature was raised to 147 ⁰ C, and after a total heating time of 14 hours by the temperature to 131 ⁰ C lowered. The total heating time was 48 hours. The product is transparent, colorless and glassy. It was tested analogously to the preceding examples, the results are summarized in Table 1. Examples 1 to 3 indicate the effect of the reaction temperature on the properties of the polymers as they result from the resulting composition.

Example 4

Films of the copolymers of Examples 1 and 3 were immersed in water for several months. After three weeks, the copolymer of Example 1 became cloudy while that of Example 3 remained clear for approximately 2 months. After 3 months, the film of Example 3 became remarkably cloudy, and the film of Example 1 is white and opaque. The water which came in contact with the film of Example 1 tasted sour, while that of Example 3 tasted tasteless. A review of the values of Table 1 makes it clear that the copolymer of Example 1 is an environmentally biodegradable substitute for polyethylene. Those skilled in the art will recognize that the physical properties of the copolymer are an excellent combination that can be used for many packaging purposes. Its tensile strength and initial modulus compare favorably with polyethylene compositions used for, for example, plastic garbage bags, general film wrapping, plastic shopping bags, layered packaging material, six-pack opener bags (AdU .: Open Bags). The shape of the stress-strain curves is nearly the same for the copolymer and for a low density polyethylene composition commonly used for garbage bag compositions. A comparison of the properties is summarized in Table 2.

Table 2: Comparison of polyethylene with polylactic acid polymers

property LDPE- ¹ ' ¹ LLDPE ¹⁰¹ lactide NA 272 Copolymer ^(c) tensile strenght 2.18 2.9 3.90 10OOpsi ASTM standard C Strain, % 261 500 280 Tangent modulus, 10OOpsi 54.9 51.0 36.6 100% module, 1.77 - 0.74 lOOOpsi 200% module, 1.82 _ 1.20 HDT, ^(dl 264psi, F 99 122

(a) Linear low density polyethylene, 5-1 ohm II 2 inches / min, our experiments.

(b) low linear density polyethylene, computer database values.

(c) L-lactate / racemic copolymer D.L-Lectl, Example 1.%

(d) Dimensional stability in towers.

The lactide polymerization can be interrupted in an incomplete reaction of the monomers to polymers in a controllable manner. This is illustrated in Examples 1 and 2. The Lactldmonomere connects very intimately with the Laktidmonomeren. Alternatively, the composition may be obtained by mixing the lactide with the previously prepared polymers. In this case, the added lactide may be the same or different in stereochemistry, that is, L, D or D, L, lactide to that used to make the polymer.

Blending can also be accomplished by blending the molten polymer in a conventional process equipment, such as a mill or a twin-screw extruder. The normally stiff, glassy lactide polymers are flexible due to the lactide and remain transparent, colorless and virtually odorless in the world. The lactide is not very volatile, requires heating and a nitrogen purge, usually at 170 to 200 ⁰ C, 20-60 minutes to remove the lactide in a gravimetric analysis. The lactide is also not visible in films under a light microscope. The lactide is present in submicroscopic terms. This flexibilization of poly-lactic acid allows it to be used as an environmental biodegradable substitute in the environment for disposable polyolefin disposable packaging films.

Examples 5-16

A series of experiments were conducted in which copolymers of L- and racemic D, L-lactide were prepared, determined with different amounts of lactide melt blend, and the physical properties of the blend as a function of the lactide composition. The monomer lactide content was tested by a previously developed isothermal, thermogravimetric analysis (TGA). The lactide content was determined before and after mixing and preparation into films.

It has been found that open rolling with two rollers results in the lactide becoming volatile at temperatures required for very high molecular weight lactide copolymers. These losses can be minimized by preparing masterbatches or by using low molecular weight lactide copolymers (and their associated lower blending temperatures). A better blend preparation and blending process was a conventional twin screw extruder that minimized volatility losses. Some results are shown in Table 3. The blends of polyactide and lactide plasticizer are very flexible and increasingly so with increasing lactide content. They are colorless and transparent. There is only a very faint (pleasant) smell of lactide, and you can not detect a noticeable taste of lactide. The plasticized film samples in Table 3 were further tear resistant, easily foldable, and could be punctured without destruction or tearing. They got a bit stiff when put in a cooler (5 ⁰ C, 40 ⁰ F), but remained flexible and foldable without breaking. These films, which are remarkably soft in hand, have a Glasumwaridlungstemperatur to below 37 ^0C. If the lactide content is less than 20%, the films have a racemic noise typical of olefin film. At higher lactide contents, the films have a stretchable and soft handle of PVC.

As shown in Table 3, the modulus of elanticity (initial tangent moduli) can be very high, as with a low linear density polyethylene (LLDPE). This indicates a potential dimensional stability. Lower moduli and tensile strengths are the same as with low density polyethylene (LDPE). As shown in Figures 1 and 2, physical properties were plotted diagrammatically as a function of lactide (s). Looking at Table 3, at a lactide content of about 17 to 20%, the strength properties are the same as for polyethylenes used for waste and shopping bags.

At lower lactide contents, the blends are consistent with polypropylene. Fines data can be compared in Table 3. Table 4 defines the conventional plastics used in the comparisons.

Table 3: Comparisons of the strength properties of plasticizing PLA (a)

example Together lactide elasticity 1% sec strain strain Fracture- strain number reduction %, TGA module module border at the strengthened. at lOOOpsl lOOOpsi lOOOpsi stretch lOOOpsi fracture 5 90 / 10.L- / D.L- 1.3 289 291 0 0 7.5 3 lactide copolymer 6 90/10, LVD ₁ L- 17.3 119 119 2.23 4 2.29 288 lactide copolymer 7 90/10, L-ZD ₁ L- 19.2 95.5 90.3 1.97 5 4.24 536 lactide copolymer 8th 90/10, L- / D, L- 19.6 88.7 88.7 1.72 4 2.12 288 lactide copolymer 9 90 / 10.L- / D.L- 20.5 50.3 50.3 1.21 5 2.16 338 lactide copolymer 10 90/10, L- / D, L- 26.5 33.7 22.9 0.32 4 2.44 546 11 LDPE ^lbl - 41.3 40.6 1.51 17 1.60 365 12 LLDPE ^{(C |} - 44.4 42.7 1.66 16 1.66 599 13 Biaxlally ^(d> oriented PE - 38.9 41.1 1.69 16 4.78 838 14 Biaxlally ¹ ·) oriented PE - 35.6 38.5 1.68 16 5.20 940 15 HDPE ' " - 127.8 120.9 3.48 9 1.95 216 16 ΡΡ ^Ιβ1 - 174 174 5.08 5 7:34 6

(a) ASTM 882; all samples were compression molded 6-1OmII films, except Examples 13 and 14; Strain rate for every 1.0 inch / inch minutes D ₁ L-LaMId is racemic.

(b) USI low density polyethylene (Petrothen No.213).

(c) Linear low density polyethylene (LLPE 6202.57) from Exxon.

(d) machine direction.

(β) Transverse to the machine direction.

(f) high density polyethylene from Phillips (HMN 6060).

ig) polypropylene from Chlsso (XF 1932, melt index 0.52).

Table 4: Data from manufacturers

supplier trade name density Recommended tensile strenght elasticity melt index and or g / cm ³ enamel when stretching module at g / 10 min variety temperature F bend LDPE (USI) Then Petro 0.924 360-550 1820 0.37 8.0 # 213 LLDPE (Exxon) 6202.57 0.926 425 1700 0.53 12.0 HDPE (Phillips) HMN 5060 0.950 425-525 3600 1.75 6.0 80% LLDPE (Exxon) LPX 86 0.927 260 - - 0.8 20% HDPE (Octenbase) processing oil polypropylene XF1932 0.91 450-500 5872 3.05 0.52 (PP-Chisso) polystyrene rl , 1.05 400 7900 4.50 1.8 (Amoco)

Table 3 presents some values for lactide and polyactide mixtures. The results do not differ significantly from similar compositions of Examples 1 and 2 prepared in other ways. However, those skilled in the art will appreciate that the precise physical properties vary depending on how intimately the mixture is, the test conditions of strength, and the fabrication technique for making the films. It can be seen from comparisons in Table 3 that the lactide polymer blends have a wide range of controllable compositions similar to many conventional non-degradable types of plastics.

Example 17

An oligomeric poly-lactic acid (OPLA) was prepared for blending with polylactides as follows. An 88% solution of L-lactic acid (956g!) Was placed in a three-necked flask (1 liter) equipped with a mechanical stirrer and a vessel thermometer and the reaction mixture was purged with nitrogen at 150-190 ° C at 200 mm Hg, 1 hour No catalyst was used except for lactic acid and its oligomers This temperature and vacuum was maintained and distillation continued for two hours until 73% of the theoretical dehydration water was removed.

The total time required was 3 hours. After this time the reaction was interrupted. The water samples and the vessel oligomer were titrated with 0.5 η NaOH, in the distillate of water some lactic acid 26.2g was detected. The vascular oligomer (OPLA) was returned to excess 0.5 N NaOH, then back-titrated with normal H ₂ SO ₄ . These values are listed in Table 5. The OPLA flows well when it is warm and shows low flow when cold. Ec has a degree of polymerization of 3.4. It was used in Example 20 where it was melt blended with the polymer of Example 19.

Table S: Characterization of OPLA of Example 1 Titratable acid,% Titrable ester,% Total, expressed as lactic acid,% Polymerization degree Percent dehydralizes, theoretically 34.4 82.4 116.8 3.4 68

Example 18

The procedure of Example 17 was repeated except that the distillation was carried out more slowly. After a 6 hour heating time during which the temperature rose slowly from 63 to 175 ^° C at 200 mm Hg, a sample from the still was titrated to give a theoretical warrior distance of 62.2%. The titration gave a degree of polymerization of 4.3. The molecular weight of the OPLA continued to increase for 2 hours by heating at 179 ⁰ C and using a vacuum pump. The OPLA was no longer soluble in 0.1 N NaOH, was water-soluble and free-flowing when cold. This material is a second example of producing OPLA with a slightly higher degree of polymerization compared to Example 1. It was mixed with polylactide in Examples 22 and 26. It is estimated that the degree of polymerization is about 6-10.

Example 19

A polymer lactide was prepared by the same methods as in Example 3. A 90/10 medium LVracemic D, L-lactide copolymer was melt polymerized using 0.02 parts per hundred of anhydrous stannous octoate catalyst. In the same way, a 100% L-Ltiktidhomopolymer (L-PLA) was prepared. The copolymer was melt blended with the homopolymer at 35O ⁰ F in a twin screw extruder at a mass ratio of 90/10 copolymer / homopolymer. Gel permeation chromatography (GPC) of the mixture gave an average molecular weight (M _w ) of 182,000 and a number average molecular weight (M _n ) of 83,000. The residual lactic monomer was 1.7 by thermogravimetric analysis (TGA) wt .-%. This mixture was mixed with the oligomeric poly-lactic acid (OPLA) of Example 17 to prepare Example 20. The strength grades are summarized in Table 6.

Example 20

The polymer ¹ of Example 19 was melt blended with the OPLA of Example 17 in an open 2-roll mill for 20 minutes at 325 ⁰ F. The mixture was compression molded into films and tested as shown in Table 6. The molecular weights of GPC were smooth monomodal distributions (M _w / M _n ) = 2.6 with M _w = 192000 and M _n = 73000.

Table 6: Properties of melt blends of 90/10 polylactides and oligomeric poly-lactic acid

example Composition, Ma .-% oligomer lactide, elasticity Fracture- strain Tg, number polymer %, TGA module, 1000 psi festigk., psi at break,% C 0 (A) (A) (A) (B) 19 100 ^(cl gwi 1.7 298 7500 3 55 20 91 '' 0 1.8 276 6113 2 - 21 100 '· ¹ 30 ⁽ⁿ 1.6 308 7478 3 58 22 70 "· 40 '' 0.4 264 6052 3 42 23 60 '·' 50 ¹⁰ 0.0 202 3311 2 38 24 50 '·' 60 "° 0.0 106 2334 25 35 25 40 '' 0.0 36 1180 129 35

(a) ASTM 882; 5-10 mildly shaped films, strain rate 1.0 inch / inch / min.

jb) Glass transition temperature by differential scanning calorimetry.

(c) A 90% blend of a 90/10 L / D, L-lactide copolymer with 10% poly (L-LaMId), Example 19.

jd) Oligomer PLA from Example 17.

(e) A blend of 80% of a 90/10 L / D, L-lactide * copolymer with 20% poly (L-lactide).

(0 Oligomer PLA from Example 18.

* racemic

Examples 21-25

The copolymer of Example 19 was melt blended with 20% L-PLA as described in Example 19. The mixture is listed in Table 6 as Example 21, which contains the analyzes and strength properties. Example 21 was again melt blended with various amounts of OPLA of Example 18 and tested as before and reported in Table 6 as Examples 22-26. Table 7 contains the QPC molecular weights of these compositions. The tensile strengths and moduli are compared with the mass% of the OPLA in Figures 3 and 4 (lower curves).

Table 7:

Relative molecular mass and glass transition temperatures of 90/10 polylactides and oligomeric poly-lactic acid

Example Composition, Ma .-% residual monomer "» GPC X ΙΟ " ³ "" ¹

Number Copolymer Oligomer% M _n M _w

M ₁ M _w M _n

Tg, '"C

21 100 ' ^d > 0 1.6 76 175 410 2.3 58 22 70 "» 30 "» 0.4 67 "» 136 299 2.0 42 23 60 '' 40 "» 0.0 61 "» 112 211 1.8 · 38 24 50 "» 50 "» 0.0 62 '' ' 114 223 1.8 35 25 40 '' 60 "» 0.0 69 '' ' 120 207 1.7 35

(a) residual monomer by TGA

 Ib) molecular mass by GPC.

(c) Glass transition temperature using OSC.

(d) A 90% blend of 90/10 L / D, L-lactal copolymer with 10% L-PIa.

(e) Example 21.

(f) Example 18.

(g) after mixing; Melt mixture on an open mill, at 326 ⁰ F.

 All O.L-lactal is racemic.

Examples 26-30

A second series of copolymers was blended with OPLA. A 92.5 / 7.5, L / D, L-lactide copolymer was prepared by the same methods as in Examples 19 and 21. This is Example 26 in Tables 8 and 9. Melt was blended with the OPLA of Example 18 on an open 2-roll mill at 325 ° F for approximately 20 minutes. The blends were compression molded into 3-5 mil thick films and their strength properties and GPC molecular weights were determined. The properties are given in Tables 8 and 9 and shown diagrammatically in Figures 3 and 4. The second set of blends gave significantly higher strength properties, although the molecular weights were lower. This may be due to the lower residual lactide monomer and / or the change in the high polymer composition. All OPLA polylactide blends were easily made into non-tacky, transparent films.

Table 8:

Properties of melt blends of 92.5 / 7.5 polylactides and oligomeric poly-lactic acid

Example Composition, wt% lactide, elasticity-elongation-elongation at Tg '^b>

Number Polymer Oligomer%, TGA modulus, lOOOpsi strength psi fraction,%

(C) (d) (a) (a) (a) C

26 , 100 0 0.2 338 10527 4 61 27 80 20 0.3 346 9144 4 ' 52 28 70 30 0.2 346 5675 2 46 29 60 40 0.6 249 5617 3 36 30 50 50 1.5 112 1984 119 36

(a) ASTM 882; 3-5mil compression molded films, elongation rate 1.0 inch / inch / minute.

(b) glass transition temperature using differential scanning calorimeter.

(c) 92.5 / 7.5, L / D, L-lactide copolymer.

(d) Example 18.

All D.L-Laktld is racemal.

Tabolle9:

Relative molecular weights of 92.5 / 7.5 L / racemic D, L-lactide copolymers

example % GPC x ΙΟ " ³ "' M " M ₁ M "/ M _n number OPLA M _n 124 228 1.95 26 0 63 108 189 1.81 27 20 60 80 125 1.66 28 30 48 96 151 1.65 29 40 59 92 141 1.64 30 50 56

(A) GPC

Examples 31 and 32

Film samples with and without plasticizer were exposed to seawater from March to May in Daytona, Florida. The pH of the water varied from 7.3 to 7.6 and the salt content from 33.2 to 38.4 ppt. The water was gradually heated from 15 to 27 ⁰ C during the test. The test samples were cut into streaks and the firmness tested before and after periodic intervals in seawater. The results are included in Table 10. All samples showed whitening and physical degradation, which increased over time. Without plasticizers, the samples showed whitening and degradation after 6 weeks in seawater. The OPLA polylactide digestion decomposed faster and showed definite proof of decomposition after 3 weeks. Incorporation of 20% lactide immediately caused whitening and clear degradation after one week of exposure.

Table 10: Physical properties after exposure to seawater

example composition Strength properties, 10OOpsi '*' Dehn fracture Strain, (%) number Seawater Elastlzitats- 1% secant border festig Flow break Exposure module module ness weeks

90/10 copolymer 0 305 292 5% L-PLA 3 <b) 315 301 6 '' 317 317 ₉ (d) 228 230 12 '' 355 343 90/10 copolymer 0 275 275 with 10% 3 <bi 291 281 oligomer ₆ (O 246 246 ₉ (d) 211 105 12 '' 103 103 90/10 copolymer 0 300 298 with 1% fumaric acid ₃ (bi 292 291 6 ^(cl 318 318 ₉ (d) 226 223 12 '' 70 122 92.5 / 7.5 copolymer 1"' FürdiePrü fungzusp with 20% LaIaId

7.6 - 4.7 7.1 - 3.1 7.3 - 3.0 6.2 - 3.0 3.9 - 1.0 6.1 - 2.0 6.8 - 2.9 3.9 - 2.0 1.4 3 2.0 1.7 - 1.0 7.0 - 3.0 6.5 - 2.5 6.9 - 2.0 6.1 - 3.0 0.8 - 1.0

(a) 0.5 χ 5-inch folie, 12-17 mils; Elongation rate 1 inch / inch / minute

(b) 15-21 C, seawater, changed regularly

(c) 20-22 C, seawater, changed regularly

(d) 22-23 C, seawater, regularly changed (β) 22-27 C, seawater, changed regularly

The above samples provide the justification that a 100% lactic acid composition can yield a flexible thermoplastic for use as flexible plastic containers. For comparison, unplasticized homopoly (L-lactide) is a highly crystalline polymer having a tensile strength of about 7000 psi at 1% elongation and an initial modulus of 500,000 psi. It is very brittle, opaque and easily cracked. It is not a well-suited thermoplastic and is not transparent either. Poly (razumisches, D, L-lactide) is an amorphous, glassy polymer having a glass transition temperature of about 5O ⁰ C, a tensile strength of about 6300psi, an elongation of about 12% and an initial modulus of 160,000 PSIL Although transparent, it is also very brittle. In stark contrast, a lactide monomer plasticized L-lactide / racemic D, L-lactide copolymer polymer is remarkably different. For example, plasticized polymers may have a tensile strength of about 3900 psi, an elongation of 431%, and an initial modulus of 56,000 psi. The plasticized polymer is clear and colorless, and the mixture must be heated above 100 ^° C. to remove the plasticizer. Although theoretically a more amorphous structure is predicted as a result of plasticization, the surprising thing is that flexible, transparent, stable compositions can be formed, and secondly, the properties that are almost perfectly suited for certain packaging purposes, such as polyethylene. The invention comes at a time when there is a need for such initial characteristics of a material that is slow biodegradable in the environment and thus can reduce the pollution problems of plastics.

It is clear to those skilled in the art that extremely intimate blends of high polymers and plasticizers are a rarity. Plasticizers provide a substantial breadth of initial physical properties and time for biodegradation in the environment.

The amount of plasticizer in the polymer depends on the desired properties of the composition. When lactide is used as a plasticizer, the preferred range is 5 to 40 mass%, whereas when only oligomer of lactide or lactic acid is used, the range may be 2 to 60 mass%. Surprisingly, it is possible to add oligomer up to 30% by weight without significantly affecting the tensile strength or the modulus. See Figures 3 and 4. The addition of 30 to 60 wt% oligomers produces significant plasticization and reduction in physical properties. This gives the composition a higher economy because oligomoric lactic acid is cheaper than high polymer lactic acid. Oligomeres can be made from lactic acid or any lactide. It is important to know that the oligomer of lactic acid normally contains significant amounts of lactic acid unless it is removed. This is an important aspect for the tailor-made production of compositions with specific properties. Those skilled in the art, also familiar with the teachings of this invention, are able to choose the reaction conditions to achieve appropriate chain lengths for the polymer and the proportions of polymers and plasticizers so as to obtain processed compositions having physical properties which are the commonly used packaging thermoplastics correspond and yourself

to decompose comparatively quickly. For example, higher levels of plasticizer give polymers with increased flexibility and increased physical toughness properties, however, an increased rate of degradation is also obtained. Furthermore, shorter chain lengths for the polymer require less plasticizer to achieve the same properties as larger chain lengths.

Further, in the first embodiment of the invention, there is proposed a process for producing an environmentally biodegradable composition which is a plasticized polymer of lactic acid represented by the formula (I). The process consists of preparing one or more lactide monomers and catalyst; Polymerizing the monomer to produce a polymer at a sufficiently low temperature so as to interrupt the polymerization reaction prior to completion of the polymerization; Control of the monomer content to determine the remaining monomer and stop the reaction before complete polymerization at a certain monomer content, so that unused monomer of a predetermined amount is included together with the polymer. The lactide monomers of the method are selected from a group consisting of D-lactide, L-lactide, meso-D, L-lactide, racemic D, L-laxide and mixtures thereof.

Optionally, additional plasticizer may be incorporated into the polymer, wherein the plasticizer is further selected from the group consisting of L-lactide, D-lactide, racemic D, L-lactide, meso-D, L-lactide, lactic acid, oligomers of lactic acid , Oligomers of the lactide and mixtures thereof. Preferably, the polymerization of the monomers occurs at a temperature below 129 ^° C. Further, the processing of the plasticized polymer into a final product is preferably at a low enough temperature to maintain the plasticizer in the polymer. This temperature can be above 129 ⁰ C. Of course, if additional monomers and / or oligomers are added, the retention of the monomer is not so critical.

Furthermore, the first embodiment of the invention proposes a process for the preparation of a polymer of formula (I) which comprises the production of one or more lactide monomers and catalyst; polymerizing the monomer to obtain a polymer and incorporating plasticizers into the polymer in a separate step, wherein the plasticizer is selected from the group consisting of D-lactide, L-lactide, DL-lactide, oligomers of lactic acid, and the like Mixtures exists.

The compositions of the invention have a tensile strength of 300 to 20,000 psi, a breaking elongation of 50 to 1,000% and a tangent modulus of 20,000 to 250,000 psi. Preferably, to replace a polyolefin, the compositions have a tensile strength of at least 3000psi, an elongation at break of at least 250%, and a tangent modulus of at least 50000 psi.

The homopolymers and copolymers of the present invention are water-insoluble but slowly degradable upon continuous contact with water. Compared to olefin compositions which are replaced by this invention, however, degradation proceeds rapidly. As a result, disposable articles made of the polymers are environmentally attractive in that they slowly degrade to harmless substances. If articles of polymers according to the invention are burned, they burn with a clean, blue flame.

Further, the first embodiment of the invention proposes a method for replacing a thermoplastic composition with the biodegradable composition of the invention, wherein the thermoplastic composition contains first orientable polymer units by replacing the first polymer units with a second orientable polymer having an unoriented tensile strength of 300 to 20000 psi , an elongation at break of 50 to 1000% and a tangent modulus of 20,000 to 250000 psi, the second polymer consisting of poly-lactic acid units of the structure of formula I, where η is the number of repeating structural units and η is an integer of 150 η η <> 20,000 and is plasticized with a plasticizer selected from a group consisting of lactides, oligomers of lactic acid, oligosides of lactide and mixtures thereof. The process is applicable to polyolefin compositions and in particular polyethylene and polypropylene as well as polyvinyl chlorides and polyethylene terephthalate. In addition to the above compilation, the process can be used for the replacement of polymers of styrene, vinyl acetate, alkyl methacrylate, alkyl acrylate. It is understood that copolymers prepared from mixtures of monomers of the specified group and physical mixtures of polymers and copolymers of the above group can be used in similar wines.

Second general embodiment

The biodegradable compositions set forth herein as a second embodiment are biodegradable to environmentally acceptable and compatible materials. The degradation intermediate: Lactic acid is a common, naturally occurring substance that can be metabolized by many organisms. Their natural end-products are carbon dioxide and water. Intended equivalents of these compositions, such as those containing minor amounts of other materials, filler or extender, may also be readily biodegradable in the environment by appropriate choice of materials. The compositions listed herein are ecologically unsound of substances because their physical destruction and decomposition is much faster and more complete than with the conventional non-degradable plastics they replace. Further, because all or most of the composition is poly-lactic acid and / or lactic acid-derived lactide or oligomer, no residue or only a small portion of a slower-degrading residue will be left. This residue has a larger surface area than the bulk product and an expected faster rate of degradation.

The preferred composition of the present invention consists of polymerizing lactic acid units having the repeating structural unit of formula I, wherein η is an integer of between 75 and 10,000 and the alpha carbon is a random mixture of D and L (or R and S) with a Overweight is one of the pure enantiomers. If η is small, then the poly-lactic acid, PLA, is easily processible, but it is considerably less if η is larger. Is η very large, z. B. 7000 or greater, the PLA is very strong but complicated for the injection molding. Preferably, η is about 500 to 3,000 for the best balance of melt processability and final physical properties. The monomers are selected with L (odor D) / D, L ratios of polymerized lactic acid or its cyclic dimer, lactide, as further discussed below. Both lactic acid and lactide provide the repeating PLA structural units - as outlined above - however, lactide is preferred because it is much easier to obtain the higher molecular weights required for good physical properties. There lactide is structure

O = C H-C

contains two asymmetric alpha carbons, there are three types of lactld, namely D ₁ D- (or D-); L ₁ L- (or L-) and meso-DL-lactide.

D-lactide is a dilactld or cyclic dimer of D-lactic acid. Similarly, L-lactide is a cyclic dimer of L-lactic acid. Meso-D, L-lactide is a cyclic dimer of D- and L-lactic acid. Razemal D, L-lactide contains a mixture of D- and L-lactide of 50/50. As used herein alone, the term "DL-lactide", meso-D, L-lactide or racemic D, L-lactide is intended to include The common term used herein means that the material is homogeneously and intimately admixed with the polymer L-PLA has inadequate processing properties, becomes slightly cracked and opaque, pure D ₁ L-PLA is easy to process, but not sufficiently rigid to be an equivalent OPS compensating product, the copolymer ratio of between 85/15 to 95/5 and preferably 90/10 L-lactide / D, L-lactide is a preferred embodiment of the invention At ratios greater than 95/5, the copolymer is difficult to form by heat without cracking and becoming opaque at room temperature / 15, the lactide copolymers exhibit lower than desired moduli for OPS compensation products. Within these limits, the copolymers are formed from the melt Plastics processing equipment rapidly cools to produce films and shapes that are clear, colorless and extremely rigid. The properties created in this way closely resemble those of an OPS.

Another advantage of this invention is that the 100% lactic acid copolymer can be used for cheaper starting materials. Corn syrup via starch and corn may be fermented to either L or racemic D, L-lactide (lactic acid) depending on the microorganism. Racemic D, L-lactic acid can be conveniently obtained via ethylene, which can be oxidized to acetaldehyde, which reacts with hydrocyanic acid to form lactonitrile, which is hydrolyzed to racemic D, L-lactic acid. Lactld can be easily made by distilling lactic acid. Ea no change in the stereochemistry of the asymmetric carbon in the transformation of lactic acid to lactide by conventional distillation / condensation process.

If the reaction of L-lactide and D, L-lactide is discussed here, it should be noted that L-lactide which specifies the reactions may also use D-lactide. Thus, the reaction gives D-lactide and D, L-lactide an equivalent product according to the method described herein, the only difference being that it turns light in a different direction.

The copolymers of the invention are preferably produced by heating the monomer mixture to form a homogeneous melt and adding a catalyst to allow the lactides to undergo ring-opening polymerization. The polymerization is preferably carried out in an inert, anhydrous atmosphere, for. As nitrogen or argon or in vacuo. Suitable catalysts include divalent metal oxides and organometailic compounds, e.g. Tin (II) octoate, zinc acetate, cadmium acetate, aluminum acetate or butanoate, tin chloride, tin benzoate and antimony oxide. Tin (II) octanoate is the preferred catalyst because of its high solubility in the monomers, ease of preparation in anhydrous form, and low toxicity. The amount of catalyst required may vary based on the monomers from about 0.02 to 2 mass%, and is preferably about 0.2%. The molecular weight and melt viscosities of the copolymers are determined by the amount of catalyst and / or chain transfer agent, e.g. B. glycolic acid, controllable. The reaction temperature of polymerization is between about 100 and 200 ⁰ C. The least color formation occurs below 140 C °, and the rate of polymerization is over 135 ⁰ C optimal. Since racemic D, L-lactide melts at 127 ⁰ C, a degree of polymerization above 127 ⁰ C is most suitable for the conversion of monomers to polymers. If clarity and transparency are required as with OPS compensation products, the inventive copolymers are polyr in an inert atmosphere above their melting points, erisiert which generally range from 125 to 160 ⁰ C. The molten lactide copolymer can be extruded from the polymerization reactor into strands and rods, cooled, pelletized and stored in bags for use in subsequent forming and extrusion operations.

Likewise, clarity of thermoformed packaging films and articles is achieved by performing molding and extruding above the melting points of the polymer and rapidly cooling the articles produced. Thereafter, the copolymers remain transparent unless heated for several hours above their glass transition temperature, Tg, and below the melting point, Tm. Slow cooling of the thermoformed webs, sheets, films, and moldings can cause spherulitic crystallinity in the copolymers, causing an improvement in the thermal stability of the articles produced, but causing some loss of transparency. Nucleating agents, e.g. Sodium benzoate, calcium lactate, and the like. may also induce a very rapid and significant crystallinity, a slight stretching of the copolymer between its Tg and sium Tm causes orientation of the polymer molecules and can substantially improve the physical properties without loss of transparency. The mixing of different types of lactide polymers or copolymers can significantly alter the physical properties. For example, the melt blend of the high melting L-lactide polymer with a low melting lactide polymer can produce a transparent material that has a sufficient level and crystallinity type to remain transparent. Those skilled in the art know that transparency in molded films, high stiffness, increased heat distortion temperature, thermoprocessability and degradability in the environment are a rare combination of properties. As a result, the polymers can be blended, nucleated, oriented, and adjusted by molecular weight to produce a large portion of the breadth of processability and final properties in the final blended thermoplastic.

The copolymers according to the invention hydrate back to lactic acid in the presence of moisture. In the presence of ambient air and moisture, hydrolysis becomes apparent in about 12 to 18 months. The copolymers then become tacky, somewhat opaque and very brittle. When immersed in water, the copolymers show distinct hydrolysis effects in one to four months depending on the composition, molecular weights, environmental temperature, surface area to volume ratio, and incorporating the particular hydrous environment of the copolymers. Further, microorganisms can reduce the lactic acid to carbon dioxide and water. The copolymers have (approximately a shelf life of several months, but disappear within about a year if they are moist throughout.

The following examples are illustrative only of the present invention. In Examples 1B to 7B, a series of compositions were prepared and tested. Eo was discovered in contrast to the prior art that there are significant differences in processing behavior and physical properties dc! Lactide / D.L lactide copolymers.

Example 1B

Into a dry, 500 ml round bottom flask was added 160 g of L-lactide (Purac, Inc., "triple-star" Sortu) and 40 g of methylated D, L-lactide (Purac, Inc., "triple star" variety). The mixture was heated for about one hour at 123-129 ⁰ C under lock and with a continuous nitrogen purge through an inlet and outlet in dom closure. The monomers form a clear melt which has been thoroughly mixed by vortexing the melt. A catalyst solution was prepared and dried by azeotropic distillation, that is, 10 ml of stannous octoate (Polysciences, Inc.) was dissolved in 60 ml of toluene; 10ml toluene with traces of water was distilled into a Dean-Stark receiver, which was vented through a drying tube. An amount of 0.20 ml of stannous octoate solution was pipetted into the melt and mixed thoroughly. The pulp lining is continued and the melt becomes increasingly viscous in the next three hours. The heating was continued at 123 to 127 ⁰ C for 20 to 24 hours. The mixture was allowed to cool to room temperature and the flask of liquid nitrogen cooled further behind a protective shield. The glass splinters and is taken out of the polymer. The copolymer is clear and colorless and is tested in a series of tests shown in Table 1D. Foils were compression molded at 17O ⁰ C in a heated hydraulic press for later tensile testing. Plates, one inch thick, were made for impact testing with Notched Izod ASTM D256 and thermoformability, ASTM, D648. The glass transition temperature Tg and the melting point (Tm) (center of the endotherm) were determined by differential scanning calorimetry (DSC).

Examples 2 B-7 B The procedures of Example 1B were repeated with the exception that the ratio of L- and racemic D, L-lactide

changed in Table 1B with the test results. The pure L-Laktidpolymer, Example 7 B, can not always good at 170-200 ⁰ C process, as it is often dangerous craze on cooling in the mold. It often becomes cloudy when cooled.

Table 1B Properties of L-lactide / racemic D, L-lactide copolymer

composition 80/20 85/15 87.5 / 12.5 90/10 90/10 95 / S 100/0 mass ratio 1B 2 B 3B 4B 5B 6B 7B L-lactide / D, L-lactide (racemic) colorless u. White Example no. transparent opaque Color / transparency 10 5 15 11 5 10 5 ' Film thickness, mil 7.9 6.9 8.3 8.6 8.2 9.2 (A) Tensile strenght, 3.5 5.8 6.0 7.1 7.2 5.1 (A) 1000psi, ASTMD882 Strain, % 289 221 694 210 268 748 _ Tangent modulus, lOOOpsi - 0.44 0.34 0.31 - 0.41 (A) Impact resistance ^(bl - 928 - - - - - according to Izod, ft-lb / in - 218 - - - - - MwJOOO's 53 53 48 44 - 46 - M _n, 10OO's - - 125 133 - 152 190 Tg.C ' "> Tm, C ^(cl

(a) hairline on cooling, (Or the test too brittle.

(b) Gokerbte samples, impact on the notched side in ViZoII thick test specimens.

(c) Olfferentlal scanning calorimetry In nitrogen at a heating rate of 10 ° C / mln.

Example 8 B

Analogously to Examples 4B and 5B, a copolymer of L-lactal / racemic DL-lactide was prepared in a mass ratio of 90/10. Into a dry, 2 liter, nitrogen-spiked flask was added 1045.8 g of L-lactide and 116.4 g of racemic D, L-lactide. An amount of 1.0 ml of anhydrous stannous octoate (0.2 ml per ml toluene) solution was added. The flask was gassed with nitrogen overnight, then heated at 141 ^° C. in an oil bath until the monomers melt and mix well. The heating slowly decreased to 126 ^° C and continued for 72 hours. The polymer slowly softened on cooling. After removal of the glass, the cloudy, colorless, glassy polymer was tested. Gel permeation chromatography gives an average molecular weight (basis mass)! MJ of f 22,000 and an average molecular weight (basis number) (M _n ) of 149,000.

A DSC of Laktidpolymers gives a unique Tm at 145 ⁰ C, as shown in Figure 10. The Laktidpolymer was melted, rapidly cooled, and tested again by DSC, and gave no crystallization or melting points. However, a Tg occurs at about 50-55 ⁰ C. The results show that the polymer can be crystalline or amorphous, depending on its thermal evolution.

Examples 9B-12B

The series of the composition were expanded using the procedure of Example 1B, except that other L- and DL-rszemische Laktidverhältnisse were used and that the heating for 2 hours at 125 ⁰ C, 14 hours at 125-147 ⁰ C and then for 2 hours at 147-131 ⁰ C was. The results are included in Table 2B.

Table 2B:

Strength and modulus properties of L-lactide and D.L-lactide copolymers

composition 70/30 60/40 20/80 0/100 Mass ratio, 9B 10B 11B 12B L-Laklid / D, D-Laktld colorless/ - - (Racemic) clear Belspiel no. 6-9 4-6 4-5 5-7 Color / transparency Film thickness, mil 6.9 6.7 5.8 5.6 Tensile strength, " ¹ 3.2 3.0 2.7 2.8 1000 psi, ASTM D638 ¹ · ¹ 287 293 275 278 Strain, % Tangent modulus 1000 psi

(a) The films are drawn with a jaw separation of 0.2 inches / min and a belt speed of 6 inches / min.

The results of the above examples show that only certain compositions have the required properties for an OPS compensation product. The main requirements for an OPS-like material are transparency and colorlessness, tensile strength above 7000 psi, a tangent modulus (a measure of rigidity) above 400,000 psi, and good thermoplasticity.

Table 3B contains some parallel comparisons of a crystal polystyrene (OPS) with a random polymer of 87.5Ma% L-lactide and 12.5Ma% racemic D, L-lactide.

Table 3 B:

Comparisons of physical properties

property Polylactic acid Crystal- Example 3 B polystyrene Kerbüchlagfestigkeit nachlzod, ft-lb / inch 0.4 0.4 Tensile strength, psi 8300 7400 Strain, % ' 6.0 4.0 Young's modulus, psi 694000 450000 Heat distortion temperature, F, under Load, 264 psi (A) 200 Specific density 1.25 1.05 Rockwell hardness (B) M 75 Softening point after Vicat.F (C) 225 Melt flow rate, D1238 (G) 40-46 ^ld) 1.7 g / 10 min ^(s) 1,6g / 10min ^m

(a) Depending on the heat history.

(b) Shore D = 97.

(c) DSC, T _n = 125 ^C C (257 F ^C) at 10 "mln.

(d) Flow rate decreases at low temperature, depending on the manufacturer.

(0 From our experiment.

Example 13 B

The copolymer of Example 2 B was compression molded several times and repeatedly shaped to determine if color developed in the films and if the molecular weights remained high. This determines whether the copolymer can be recovered, an important consideration for manufacturing practices. The results of Table 4B demonstrate that the copolymer remained completely transparent and colorless after repeated heating and repeated compression despite the fact that the copolymer was repeatedly exposed to air at elevated temperatures.

Table 4B: Influence of molding on lactide copolymer

Example Number

procedure

Appearance

10OO's

M _n 10OO's

M _w / M _n

example not shaped, Completed _2B (.) directly from the transparent polymerization u. colorless example Experiment 2 B Completed 13 B " ¹ after shaping transparent u. colorless example Experiment 2 B Completed 13B ^(l) after 6 times transparent shape u. colorless

928

301

137

218 135 56.7

2.22

2.42

(a) 85/15 L-lactal / racemic D.L-lactide copolymer.

(b) compression molding at 167 ° C (333 ° F), 7 minutes, 6 mil film.

Examples 14B-18B *

The copolymers of Examples 2B, 3B and 6B were compression molded into films of approximately 20 to 30 mils thickness and placed in a heated Instron tester in which the films were s.fold their length at 83 ⁰ C and a speed of 0.5 inches / min were stretched. The films were rapidly quenched from the instron and found to have a thickness of 5 mils. They were clear and colorless. Tensile properties were determined and summarized in Table 5B. When stretched 8-1 times their length, the films show evidence of crystallinity formation by haze development and some loss of transparency. The results prove that it is possible to produce very thin films with adequate stiffness and transparency for an OPS compensation product. Thus, despite the higher density of lactide copolymers compared to polystyrene, less material can be used for rigid OPS compensation products.

Table SB: Properties of L-lactide / racemic D, L-lactide copolymers by orientation "'

Together 85/15 85/15 85/15 87.5 / 12.5 95/5 translation, 14B 15B 16B 17B 18B Mass ratio 5.5 5.0 6.5 5.0 4.0 L-lactide / D, L-lactide (Racemic) 14.0 14.7 15.0 13.0 16.0 Example Number 31.5 15.4 30.0 23.8 37.4 Film thickness, mil Tensile strenght, - 564 419 432 513 lOOOpsl Strain, % Tangent modulus, lOOOpsi

(a) Bx oriented at 83 ⁰ C using egg before stretching speed x 0.5 inches / minute on the Instron.

Example 19B

Films made from lactide copolymers of Table 1B were immersed in water at an interval of several months. The copolymers remained clear for two months, after 3 months a slight haze developed. After setting up the piece in humid air and with frequent handling, the sheets apparently remain unchanged for a year, although the Instron values show a slow decrease in strength and elongation after several months. In a landfill, the buried films disappeared in 6 months to 2 years, depending on humidity, pH, temperature, composition, surface area to volume ratio and landfill biological activity. All foils burn with a clean, blue flame.

Example 20B

The lactide copolymer of Example 5B (quenched, compression molded film) was tested by DSC and has a Krlstallinität noted below 2% in the vicinity of 13O ⁰ C, see Figure 5. ^r ine Ve inch thick sample of the copolymer of Example 5 B was de-stressed in an oven at 185 ^° C. for 16 hours. The sample became cloudy, and the DSC of the sample

gave a significant increase in crystallinity. See Figure 7. The sample showed heat distortion at SO-95 ° C at 264 psi. A similar sample showed, without annealing, a heat distortion temperature of 50-55 ⁰ C, which corresponds to their Tg

equivalent.

Example 21B

5mA .-% of calcium lactate were mixed on a heated mill with the Laktidcopolymer B of Example 5 at 170 ⁰ C for about 5 minutes. The mixture was pulled off the roll as a web and tested, it was stiff, strong and cloudy. A light microscopic examination at 82X showed heterogeneous regions in the size range of several microns up to 30 microns. A DSC showed a substantial increase in crystallinity near 145 ⁰ C, see Figure 8, which was retained by urine reheating on cooling. The above results show, compared to Examples 8B, 2OB and 21B, that nucleating agents more rapidly and more effectively produce crystallinity of lactide nymphymes. One can nucleating agents, for. B. seize the carboxylic acids, salts of lactic acid are preferred.

Example 22 B

In a BOO ml 3-necked round bottom flask equipped with a mechanical stirrer and an inlet and outlet for nitrogen, 180.7 g of L-lactide and 40.2 g of racemic D, L-lactide were added (both Boehringer and Ingelheim, variety S). , The contents of the flask were heated to 11O ⁰ C under a blanket of nitrogen to melt the lactides and 20.1 g were Polyetyren (Amoco R3, Schmelzlndex3,5g / 10mln) was added. The polystyrene swelled highly and partially dissolved stand with stirring overnight while the temperture rose to 105 ⁰ C. The temperature was lowered to 141 ⁰ C, and 0.2 ml of anhydrous ZinndDoctoat solution (0.2 ml / ml toluene) was added. The agitator was turned off and the lactide was polymerized for three days at 141 ⁰ C. The heavily swollen polystyrene floated up after switching off the stirrer. The lower polylactide phase was cooled and analyzed by DSC. The sample had a low Tg, approximately 35 ⁰ C, and on the other hand, lacked visible temperature transitions. Molded films are clear, colorless and very flexible. These results indicate that the polystyrene completely breaks the crystallinity formation.

Example 23B

The lactide copolymer of Example 8B was blended on a mill with 20% by weight of the L-lactide homopolymer prepared in Example 7B. A sample of the homopolymer was analyzed by DSC, see Figure 11. The mixed sample was tested by DSC and found to have a Tg of 59-63 ⁰ C and distinct Tm values at 150 and 166 ⁰ C, see Figure 12. The films were clear to slightly cloudy depending on their cooling rate after pressing. Cooled Prober, crystallize easily when heated to about 80-9O ⁰ C. As a result, the heat resistance of the mixture is rather high. The mixture becomes cloudy at 80-90 ⁰ C, but does not bend when heated as the unblended 90/10 copolymer. The strength values contained in Table 6B are from unorionized molded films and can be compared to similarly obtained values for polystyrene.

Table 6 B. Comparative of Polylactide Blend of Example 23B with Crystal Polystyrene

Example 23B " ¹ crystal polystyrene ¹¹ · ^{b |} Film thickness, mil 8th 14 Tensile strength, ASTM D882,1000'spsi 7.7 6.0 Elongation at break,% 6.5 3.2 Tangent modulus, 1000'spsi 323 267

(β) Thin films, un-apertured, compression-molded test specimens, (b) melt index 1,7.

This example illustrates that the melt blend is an excellent way to improve the properties of the copolymer so as to obtain advantageous properties as in polypropylene. The higher the content of the L-lactide (or D-lactide) -based homopolymer mixed with the polymer, the higher the heat distortion resistance, but also the haze increases. Accordingly, one can combine the addition of a homopolymer with other methods to increase polystyrene-like properties while still maintaining clarity.

As another example, the orientation of films made from the polymer increases the strength properties. With 8-10-fold delay, the physical properties increase, but the material becomes cloudy. For this reason, the degree of orientation must be controlled and combined with the other properties modified methods to achieve optimal polystyrene-like characteristics. .

Examples 24 B-27 B

Examples 24 B-27 B were polymerizations of lactide with controlled levels of chain transfer agents, demonstrating that molecular weights were reduced using chain transfer agents, e.g. As glycolic acid can be controlled. The results are shown in Table 7B. There is a nearly straight relationship between the amount of chain transfer agent and the reciprocal average (mass) molecular weight. A preferred chain transfer agent is lactic acid.

Table 7 B. Relative molecular weight control using chain transfer agents

Example- PPH cf * "' M _n "" tvi _w M _w / M " number CTA '13500 107300 8.0 24 B 0.22 12800 66700 5.2 25 B 0.45 7300 29900 4.1 26 B 0, d0 4700 13900 2.9 27 B 1.80

(a) Glycolic acid as Kettan's carrier (CTA) per hundred parts of lactide in the polymerization batch.

(b) Gelpermeatlonschromatographle, in tetrahydrofuran solution, 23 ⁰ C with 10 ', 10 ^s, 10 * and lO'Anstrom columns, number-average M _n, and weight average M _w, Molekölmaesen are calculated compared to monodisperse polystyrene standards.

Example 28 8

A 4-omni-thick, compression-molded sheet of the lactide copolymer of Example 2 B was used as a barrier by ASTM methods

checked. The results are included in Table 8B. The lactide copolymer is a much better barrier film for carbon dioxide and

Oxygen as polystyrene. Compared to some other barrier films, the lactide copolymer is an adequate barrier film for many Packaging areas. Table 8B:

Example 288 Gas Permeability ¹ ' ¹

units Laktld- Crystal '" ¹ terephthalic Vinyl diene ^(bl copolymer. polystyrene terephthalate vinyl chloride Example 2 B Chloride- copolymer cmViOOsq / Customs 24h / atm CO ₂ 32.1 900 15-25 3.8 to 44 O ₂ 19.9 350 6-8 0.8 to 6.9

(a) ASTM 01434-5, Example 2 B was a 4.0 mil compression molded film.

(b) Values from Modem Plastics Encyclopedia.

Example 29 B

Ve inch thick sheets of lactide copolymers of Examples 1B-6B were immersed overnight in a mixture of petroleum ether and methylene chloride. At ratios of 70/30 to 60/40 petroleum ether / methylene chloride, the copolymers foam in boiling water. It forms irregular but well-foamed foams.

Example 3OB

A comparison was made of the melt viscosities of a commercial crystal polystyrene (Type 201, Hutsman Chemical Corp.) with the lactated polymer of Example 8B. The melt index, ASTM D1238 (G) of polystyrene was 1.6 g / 10 min at 200 ⁰ C using a 5 kg Standard mass. The melt index of Laktidpolymers was under the same conditions at 40-46g / 10min, but the value was at 160 ^o C8,0g / 10min. One received a more detailed comparison of the

Melt viscosities by observing the melt viscosities of the two polymers in an Instron Capillary Viscometer.

The results of the comparison are shown in Figure 9. The shear rates normally encountered during the extrusion and injection molding process are about 100 to 1000 χ 1 / s. A review of the data in Table 9 zoigt that the melt viscosity of the Laktidpolymers at 16O ⁰ C is very similar to that of polystyrene at 200 ⁰ C.

The above results illustrate that lactide polymers are treated at lower temperatures than polystyrene by means of

process can be processed from the melt.

Examples 31B-34B

Small test polymerizations of purified (recrystallized and dried) meso-lactide (meso-D.L-lactide) as the homopolymer and the copolymer were performed. The molecular weights were determined by GPC and compared to the analogs of D, L-lactide. The results are shown in Table 9B. The polymers were melt pressed into films and their physical properties determined and compared as shown in Table 10B. Within study differences in web thickness and molecular weights, the copolymers are the same within experimental error. The homopolymer of meso-lactide is slightly lower.

Table 9B:

GPC molecular weight comparisons of meso and racemic lactide polymers and copolymers

Example no. Together Rest- M _n Μ " GPC x 10 " ³ Polymer- elasticity Strength at Stretching at film thickness M _w / M _n i reduction monomeric% 97.5 341 M, Together module elastic limit fracture 3.49 31 B D, L-PLA _ 62.5 152 757 reduction 10OpSi 100 psi % mil 2.42 32 B 2.76 29 142 264 homopolymer 278 5.6 2.8 5-7 1.67 33 B 1.67 91.3 201 301 from 2.20 34 B Meso PLA - 350 D, L-lactide Table 10B: 90/10, L- / meso homopolymer 345 3.8 3.5 9 90/10, J.-D, l. · Comparison of physical properties of D ₁ L and meso-lactide polymers and copolymers '*' from strain Example- Meso-lactide speed number 90/10, L-meso 190 7.9 3.8 12-15 Inches / min Lactide-copoly 0.25 31B mer 90/10, L- / D.L- 323 8.6 4.6 4-6 Lactide-copoly 0.25 32 B mer 0.25 33 B 0.25 34 B

(a) Molded film.

A comprehensive description of the composition of the second embodiment of the invention includes an environmentally degradable polymer consisting of lactic acid units of the structure of formula I wherein η is an integer between 75 and 10,000 and the alpha carbon is a mixture of L and D. -Configurations with a preponderance of either D or L units, the polymer being a replacement for polystyrene. The D and L moieties of the polymer may preferably be prepared from L-lactide or D-lactide at 85-95 parts by weight and D, L-lactide at 15-5 parts by weight. An environmentally friendly biodegradable composition having improved properties similar to that of polystyrene contains mixtures of a physical mixture of polymerizing lactic acid units of the structure of formula I wherein η is an integer between 75 and 10,000 and the alpha carbon is an irregular mixture L and * D configurations are overweight of either D or L moieties, a lactide homopolymer of D-lactide or L-lactide. Compositions with η equal to an integer between 150 and 10,000 give a good balance between strength and melt processability.

A general description of the method of making the composition of the second embodiment involves mixing with a catalyst, heating and melting the L-lactide or D-lactide monomer and the D, L-lactide monomer, wherein the L-lactide monomer or D-lactide monomer has a Proportion of 85 to 95 parts by mass and D, L-Laktidmonomer in a proportion of 15 to 5 parts by mass is present, and form an intimate solution; the polymerization of the solution and the treatment of the polymer to modify its properties to make it suitable as a replacement for polystyrene. One can control the properties of the composition by adding a nucleating agent; Adding a D-lactide or L-lactide homopolymer by mixing to produce a physical mixture; Orientation of the polymer; by adding a nucleating agent and a D-lactide or L-lactide polymer by mixing; by adding a cadmium binder and a D-lactide or L-lactide polymer by mixing and orienting the polymer; by adding chain transfer agents to the polymerization step to adjust the properties for a polystyrene replacement; by stress relief at a higher temperature and by addition of additional plasticizer, wherein the plasticizer is selected from the group consisting of D-lactide, L-lactide, meso-D, L-lactide, lactic acid, lactide oligomer, lactic acid oligomer and mixtures thereof. When a monomer is selected as the plasticizer, an exclusive composition can be obtained by adding a monomer which is stereochemically different from that used to obtain the polylactide in the composition. Analogously, the addition of an oligomer which differs stereochemically from that which can be obtained during the polymerization of the polymer gives an exclusive product. Color bodies can be excluded if one carries out the polymerization in an inert atmosphere and at reaction temperatures preferably at 14OX or below. Various combinations of the above treatments may be used to obtain the optimum properties that will be appreciated by those skilled in the art once they understand the teachings of this invention.

As can be seen from the aforementioned first type of injection, a higher monomer or oligomer content can have a significant effect. In the present second embodiment, lower monomer or oligomer moieties are preferred to provide rigidity. A plasticizer content of 0.1 to 5% is preferred. The composition usually contains plasticizers in a proportion which depends on the polymerization conditions or the amount added after the polymerization. The added monomer used as the plasticizer may be selected from the group consisting of D-lactide, L-lactide, meso-D, L-lactide, racemic D, L-lactide, and mixtures thereof. It is also possible to add oligomers of lactide or lactic acid. Exclusive compositions can be obtained by adding monomers or oligomers that differ stereochemically from those used for the polymers in the composition.

Further, according to the second aspect of the invention, there is provided a method of replacing a thermoplastic composition with the biodegradable composition of the invention, wherein the thermoplastic composition comprises orientable first polymeric structural units by exposing the first polymeric structural units to a second orientable polymer having an unoriented tensile strength of at least 5000 and a tangent modulus of at least 200,000 wherein the second polymer contains poly-lactic acid units of the structure of formula I, where η is the number of repeating units and η is an integer between 75 S η <10,000. The alpha carbon is a mixture of L and D configurations with one overweight of either D or L moieties, with the polymer of L or D lactide of 85 to 95 masses and D, L lactic d 15-5 parts by weight is prepared and plasticized with a plasticizer from a group consisting of lactide, oligomers of lactic acid, oligomers of lactide and mixtures thereof between 0.1 to 5.0Ma .-%.

Contemplated equivalents of the compositions of the invention are those containing minor amounts of other substances. If desired, compositions prepared according to this invention can be prepared by adding a crosslinking agent, other plasticizers, a dye, a filler, and the like. modify.

The compositions mentioned herein can be melt-made into useful articles of manufacture having a self-supporting structure, e.g. B. Disposable container, Eßutensilien, trays, plates, cups, individual service trays, syringes, medical trays, packaging films u.a. The compositions are useful in that they have the properties of common polystyrenes and therefore replace them while still degrading in the environment. The compositions are particularly suitable for those articles which are intended for single use or short term use before being discarded.

Third general embodiment

A third common embodiment treats the blend of poly-lactic acid (PLA) with polystyrene (PS), polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP). The third embodiment illustrates that the poly-lactic acid is melted compatible with these conventional thermoplastics as well as the influence on their physical properties. The environmentally degradable compositions set forth herein are at least partially degradable. That is, the poly-lactic acid portion of the composition decomposes relatively rapidly as compared with the stable proportions of the mixture and causes physical deterioration of the mixed substances. For example, if they are intimate and homogeneous blends with low white districts, the physical degradation destroys the original product. The noted compositions provide environmentally acceptable materials since their physical degradation and degradation are much faster than with conventional non-degradable plastics. There continues to be one

significant portion of the composition may be poly-lactic acid and / or a lactic acid or oligomer derived from the lactic acid, leaving only a small portion of the slower degrading thermoplastic residue (eg, polystyrene). This residue has a larger surface area and it is likely to decompose faster than the mass product produced. D-lactide is a dilactone or a common D '> of D-lactic acid. Analogously, L-lactide is a cyclic dimer of L-lactic acid. Meso-D, L-lactide is a cyclic dimer of D- and L-lactic acid. Racemic D, L-lactide contains a mixture of 50/50 D- and L-lactide. When used alone, the term "D, L-lactide" is intended to include meso-D, L-lactide or razt. D, L-lactide, and poly-lactic acid may be prepared from one or more of the above.

Example 1C

Polystyrene was mixed by means of solvent with poly-lactic acid and poured by means of solvent from CH ₂ Cl ₂ and determines the optimal compatibility. The solvent-cast films were translucent and apparently "non-colored." A sample appears homogeneous to the naked eye and resists folding and handling without tearing.A light microscopy study shows white areas of 3 microns and below at 310x magnification is obviously very compatible, showing no change over 2 years in terms of "fogging" by volatile substances, nor does its physical properties provide evidence of degradation.

Example 2 C Analogously 8525 polypropylene from Hercules melt blended in a Brabender with poly-lactic acid at 400 ⁰ F. The The ratios of PP / PLA produced were 100/0 for the control, 90/10 and 75/25. ' Examples 3 C-5 C Melt blends of poly-lactic acid with polyethylene were prepared. Both a polystyrene with high relative Molecular mass (Piccolastic, E-125, Hercules) as well as a low molecular weight polystyrene (Piccolastic, D-100)

were examined. Also used was a multipurpose polystyrene (Huntsman polystyrene 208), a crystal polystyrene. These were mixed in a Brabender at 32b ⁰ F with different ratios of poly-lactic acid.

The polystyrene / poly-lactic acid ratios used were 100/0 for the control and 90/10 and 75/25 for the control Multipurpose polystyrene Huntsman 208. Examples 6C-7C

Two types of polyethylene terephthalate (Goodyear's "Clearstuff" and Eastman's Kodapak TN-0148) were used, which were dried overnight at 90 ° C and melt blended with poly-lactic acid at 525 ° F in a Brabender for only a few minutes to reduce poly-lactic acid the melt viscosity.

Examples 8C-16C

The control examples and blends for polyp, ipylene, general purpose polystyrene and polyethylene terephthalate (Eastman's) from Examples 2C-7C were milled in an Abbey mill and compression molded into about 5 mil thick films. Polypropylene-poly-lactic acid films were produced at about 400 ^° F .; Polystyrene-poly-lactic acid films were obtained at 250-300 ° F; Polyethylene terephthalate-poly-lactic acid films were prepared at about 525 ^° F. After conditioning at 50% relative humidity and 23 ⁰ C, 24 hours, they were tested on the Instron. The control examples were treated equally. Samples of the molded film were placed in an Atlas Weather-O-Meter (cycles of 102 minutes of sunshine and 18 minutes of rain) to determine weather resistance. The results for these examples are included in Table 1C.

Examples 17C-19C

Three samples of 100% poly-lactic acid using poly (DL-lactic acid) were prepared as mentioned above, but with a film thickness of 10-15 mil. The tests were performed as in Examples 20C-27C, except in that the second sample was tested after 82 hours exposure to 50% relative humidity at 72 ° F.

Examples 20 C-27 C

High density polyethylene, HDPE, (0,960g / cm ³⁾ was melt blended with poly-lactic acid in a Brabender Plasticorder at 151 ⁰ C for 10 minutes. Mixture ratios of high density polyethylene / poly-lactic acid of 100/0 were used for the controls, 90 / 10.80 / 20 and 50/50. Two samples each were made. The blends were ground in an Abbey mill and compression molded into 10 to 15 mil sheets. The films were examined in an Atlas Weather-O-Meter for 51 minutes under carbon arc and 9 minutes water spray. The temperature was varied from ambient to 14O ⁰ F. Tensile, elongation, and tensile stress classifications were performed on the samples as shown in Table 2C.

Examples 28 C-33 C Never polyethylene. 'strength density, LDPE (0.917 g / cm ³⁾ was treated with poly-lactic acid in a Brabender Plasticorder at 151 ⁰ C

10 minutes. . "Izgemischt. Blend ratios for low density polyethylene / poly-lactic acid of 100/0 for the controls, 90/10 and 50/50 were used. Two samples each were made. The samples were treated as in Examples 2OC to 27C. The results are shown in Table 2C.

Example 34C

Into a 500 ml three-necked round bottom flask equipped with a mechanical stirrer and an inlet and outlet for nitrogen were added 180.7 g of L-lactide and 40.2 g of racemic D, L-lactide (both Boehrlnger and Ingelheim, variety S) , The contents of the flask were heated to 110 ⁰ C under Stlckstoffbeschleierung to melt the lactides and 20.1 g were polystyrene (Amoco R3, melt index 3.5 g / 10 min) was added. The polystyrene swelled highly and partially dissolved calibration while stirring overnight and the temperature rises to 185 ⁰ C. The temperature was lowered to 141 ⁰ C, and there were 0.2 ml anhydrous tin (II) octoatlösung (0.2 mL / ml toluene). The stirrer was switched off and the lactides were allowed in

Polymerize 141 ⁰ C for three days. The heavily swollen polystyrene floated up after switching off the stirrer. The lower polylactide phase was cooled and tested by Differential Scanning Calorimetry (DSC). It has a low Tg, about SS'C, on the other hand, it lacks obvious temperature changes. Molded films are clear, colorless and very flexible. These results indicate that under these conditions polystyrene completely interrupts crystallography.

Example 35 C

Poly-lactic acid was mixed on a rolling mill with crystal polystyrene. The mixture showed an excellent * Compatibility of polystyrenes dispersed in poly-lactic acid. Thus, 5% by weight of polystyrene were in a L / racemic DL-Laktldcopolymer with a ratio of 90/10 on a two-roll mill at 17O ⁰ C dispersed. The material became cloudy

and showed a considerable crystallinity in a thermal analysis. The example demonstrates that under these conditions

Polystyrene easily causes a crystallinity in poly-lactic acid. A thermal analysis of the material, see Figure 13, shows

that the material even remains crystalline when heated and cooled.

Examples 34C and 35C illustrate that poly-lactic acid blended with the environmentally non-degradable plastics

Here, in the mixture, final properties can be produced which depend on the mixture or applied mixing technique.

Melt blends of all types prepared on the Brabender showed a heterogeneous particle size of 10 microns or

underneath. The tensile strengths were determined before and after a simulated ventilation. After 1248 hours (52 days) in the Atlas Weather-O-Meter, all polypropylene samples became white, extremely brittle, and could not be tested. The

Polypropylene samples were rechecked at shorter intervals as shown in Table 1C. After approximately 300 hours of weathering in the Atlas Weather-O-Meter, the samples showed significant degradation in

the environment.

The polystyrene mixtures with poly-lactic acid showed an obvious after a simulated 300 hours of ventilation Degradation in the environment. Even with polyethylene terephthalate derivatives, degradation in the environment took about 300 hours

visible.

Table 1C; Tensile strength of films before and after accelerated ventilation '*'

mix Tensile strength ^<bl /% elongation after hours in front 310 400 relationship and 1665/61 585 / 1.6 494 / 1.7 material 1 568/61 954 / 3.2 346 / - 100 / 0PP / PLA ^(cl 1124/14 370 / 1.1 254 / 1.0 90/10, PP / PLA 3200 / 2.0 1 066 / 1.0 - 75/25, PP / PLA 2350 / 2.0 582 / 1.0 - 100/0, PP / PLA ^(e) 1493 / 1.6 404 / 1.0 - 90/10, PS / PLA 3036 / - 3509 / 3.0 - 75/25, PS / PLA 2147 / - 1 378 / 3.0 - 100 / OPET / PLA '·' 2743 / - 2041 / 3.0 - 90/10, PET / PLA 75/25, PET / PLA

(a) Weather o meter, cycle of 120 minutes of sunshine, 18 minutes of rain

(b) 0.05 in / min on the Instron.

(c) Hercules Polypropylene 825.

(d) Huntsman.208.

(b) Tennessee Eastman, Kodepak TN 0148.>

The poly-lactic acid, the high density polyethylene, the low density polyethylene and their blends were evaluated for physical strength before and after simulated ventilation. The results are shown in Table 2C.

-29- 299 630

Table 2C: Physical properties of polyethylene (PE), poly-lactic acid (PLA) and their mixtures before and

after weather-O exposure

Material " ¹ Material- Weather 0 meters ^(o1 Zugfestigk. 3640 1320 Elongation '" ¹ Type of strength • brittle mix Exposition, psi 1400 1250 until break,% for lack of brittle relationship hours 3480 1190 brittle Polymer / PLA 1720 855 deformable 100% PLA ^{(i |} 0/100 0 6030 3180 1160 2.2 brittle 100% PLA 0/100 _o ro 6670 2160 125 (too brittle for the test) 2.1 deformable 100% PLA 0/100 82 (too brittle for the test) 2720 brittle 100% HDPE ^(el 100/0 0 233 (for the test too brittle) 8th brittle 100% HDPE 100/0 233 0 1 brittle HDPE / PLA 90/10 0 126 7 brittle HDPE / PLA 90/10 233 0 1 brittle HDPE / PLA 80/20 0 125 4 deformable HDPE / PLA 80/20 126 0 2 deformable HDPE / PLA 60/50 0 2 ^% deformable HDPE / PLA 60/50 deformable 100% LDPE " ¹ 100/0 80 deformable 100% LDPE 100/0 67 brittle LDPE / PLA 90/10 31 LDPE / PLA 90/10 14 LDPE / PLA 50/50 4 LDPE / PLA 60/50

(a) Molded film 10-15 mils thick.

jb) Melt Blend In Brabender Plastlcorders, 10 min., 161'C.

(c) S1 min with carbon arc u. 9mtn Lei water boost for every 1h cycle. Temperature varies from ambient to 140'F.

(d) Elongation at Maximum In the Elongation Curve.

(e) poly (D, L-lact dsaure!), (n) = 1.16 dl / g, 26 ⁰ C.

(0 After 82 hours exposure in 60% RH, 72 ⁰ F.

(g) high density polyethylene, density 0.960 g / cc, melt index 0.6 g / 10 min.

| h) Low density polyethylene, density 0.917 g / cc, melt index 0.26 g / 10 min.

Poly-lactic acid and its blends were much more biodegradable than pure low or high density polyethylene. The high density polyethylene samples decomposed essentially without mass loss, while the polyethylene-polylactic acid mixtures showed mass loss, especially when poly-lactic acid detected microscopically on the surface of the film was exposed. High density polyethylene decomposed upon exposure to photochemically active light, as could be demonstrated microscopically.

For all samples, as the percentage of poly-lactic acid increased, the tensile strength decreased before and after simulated ventilation. Incorporation of poly-lactic acid caused faster degradation in blends of polypropylene, polystyrene, polyethylene terephthalate, and high and low density polyethylene. Presumably, the photochemically effective light as well as the hydrolysis of the polyester decomposes the polymer. The small size of globular, microheterogeneous white districts of the mix are undoubtedly poly-lactic acid, which is the most buried. Therefore, the hydrolysis of the poly-lactic acid proceeds slowly. A faster degradation via hydrolysis can be achieved by regulating the location of the poly-lactic acid. This, in turn, is due to the rheology of the mixture during melt blending. The small size of the dispersed, heterogeneous white districts indicates good compatibility of the blended polymers. In a simulated landfill where light was excluded, the control mixtures and mixtures show much slower degradation rates. On hydrolysis alone, the poly-lactic acid samples slowly turned white while the mixtures were qualitatively unchanged for the duration of the tests.

In contrast, the addition of small amounts of non-degradable thermoplastics to poly-lactic acid to make compatible blends using, for example, polypropylene, polystyrene, polyethylene terephthalate, and high and low density polyethylene inhibits the degradation rate of the poly-lactic acid. A preferred range for compositions is 80-99 wt% poly-lactic acid.

A general description of the environmentally degradable composition includes blends of a physical blend of poly-lactic acid (polylactide) and a polymer selected from a group consisting of a polymer of ethylene terephthalate, a polymer or copolymer of styrene, ethylene, propylene, vinyl chloride, Vinyl acetate, alkyl methacrylate, alkyl acrylate and mixtures thereof. Further possible mixtures of the compositions are listed below in the treatment of the Vorfahrenbeispiele of the invention.

The blends preferably use a physical mixture of poly-lactic acid of formula I wherein η is an integer between 75 and 10,000 and a polymer selected from a group consisting of polystyrene, polyethylene, polyethylene terephthalate and polypropylene and compositions discussed below consists. A preferred composition is that in which the poly-lactic acid contains from 6 to 50% by weight of the composition. A preferred composition has a poly-lactic acid content of 10-20%.

The polymers selected from the above group taken as added polymer may be used alone or in combination. The group is not limited to those mentioned above because other types of polymers are known to be compatible with poly (lactic acid). These include polymers and copolymers from the group comprising ethylene, propylene, styrene, vinyl chloride, vinyl acetate, alkyl methacrylates and alkyl acrylates. It is to be understood that the term copolymers as used herein includes polymers of mixtures of the monomers and the group listed. Physical mixtures of the polymers and copolymers of the above group are equally applicable to the invention.

The third embodiment also proposes a method for producing the composition. It involves the preparation of a poly-lactic acid, the selection of a polymer from a group consisting of a polymer of ethylene terephthalate, a polymer or copolymer of styrene, ethylene, propylene, vinyl chloride, vinyl acetate, alkyl methacrylate, alkyl acrylate and their physical mixtures and blending the polymers , Mixing may be accomplished by melt blending on a rolling mill or by mixing in an extruder or by other mechanical means. The produced poly-lactic acid preferably has the formula I. It is also proposed a method of producing the composition according to the invention which comprises providing a lactide selected from a group consisting of D-lactide, L-lactide, Meso D, L-lactide, racemic D, L-Lactld and mixtures thereof; the selection of a polymer from a group consisting of polymers or copolymers of styrene, ethylene, ethylene terephthalate, propylene, vinyl chloride, vinyl acetate, alkyl methacrylate, alkyl acrylate and their physical mixtures. The selected lactide and polymer are mixed and heated to melt the lactide and at least partially dissolve the polymer. Finally, the lactide is at least partially polymerized to obtain a mixture of polylactide, unpolymerized lactide monomer, and the selected polymer. The polymerization is preferably controlled by controlling the amount of lactide remaining and by interrupting the polymerization at the desired level. If desired, the polymerization can be carried to the end. Additional lactide monomer, lactic acid, lactide tar, lactic acid oligomer and mixtures thereof can be added as plasticizers in appropriate amounts to obtain the desired properties according to the first general embodiment, it will be apparent to those skilled in the art that the ratios of poly-lactic acid and added polymer will vary can vary considerably from their mutual solubilities. The solubilities, in turn, vary with the intensity of the mixing and the mixing temperature. By adding both the poly-lactic acid and the added polymer to a mutual solvent, an intimate solution is obtained. The use of a solvent is impractical for many technical processes. More practical is a physical mixture, eg. B. a melt mixture on ei.iem rolling mill or in an extruder. However, it must be controlled to obtain an intimate mixture, that is, higher shear is required to achieve the desired intimate mixture. Even with an intimate mixture, the various polymers need not be compatible, that is, they can still separate into relatively large heterogeneous white areas, e.g. B. 10 to 100 microns or above. This results in a "colored" mixture or mixture with low properties It is surprising that the lactic acid mixes readily with many other polymers, including polar and non-polar polymers.

The temperature of the melt blend of the poly-lactic acid with other polymers may be varied to adjust the ratios of the poly-lactic acid with one or more added polymers. At lower temperatures, the solubilities may not be adequate, while too high a temperature causes decomposition of the mixture. A general temperature range is 10O-220 ° C, and the preferred range 130-180 ⁰ C. Equally important are the melt viscosities of various polymeric components. As the molecular weight increases, the viscosities increase very much. By regulating the ratios of the poly-lactic acid and the added polymer or polymers, the temperature, the type and duration of mixing, and the molecular weight, a wide range of blends can be obtained. For example, the poly-lactic acid can be dispersed into the added polymer or polymers, or vice versa, and the size and geometry of the dispersed phase varies significantly, from discrete spheres to bundles of different diameter or lengths. This results in a wide range of physical properties and degradation times in the environment. The percent mass ratio of the poly-lactic acid to the selected polymer may be between 99: 1 to 1:99.

When the lactide monomer is used to dissolve the added polymer and the lactide is subsequently polymerized, the temperature during mixing and polymerization must be balanced between the mutual solubilities and the reactivity of the lactides. Higher temperatures generally result in a lower molecular weight poly-lactic acid. Another embodiment of the invention is mixing at one temperature and polymerizing at another to obtain variants in the geometry of the phase being discussed, as discussed above. The compositions chosen herein can be melt-fabricated into useful self-supporting articles such as disposable containers, utensils, trays, plates, cups, individual service dishes, syringes, medical trays, packaging films, and the like. 8. The compositions are useful in that they can have the properties of common plastics and therefore replace them and even degrade in the environment. The compositions are especially useful for articles that are used only once or have a short life before being discarded.

Fourth general embodiment

Included in the fourth embodiment of the invention are such impact modifiers which are elastomeric and melt compatible with poly-lactic acid. By "melt-compatible" is meant any of those polymers that can be intimately mixed with poly-lactic acid, as set forth in the third general embodiment The mixture gives a substantially homogeneous mixture.

The environmentally degradable compositions set forth herein are at least partially degradable, that is, the poly-lactic acid portion of the composition decomposes relatively rapidly relative to the more stable portions of the blend and causes physical deterioration of the blended material. For example, if the composition is intimate and homogeneous mixtures with small white districts, it destroys the physical deterioration of the original product. The compositions herein provide environmentally acceptable materials because their physical degradation and degradation is much faster than conventional non-degradable plastics. Furthermore, since a major portion of the composition will be poly-lactic acid and / or a lactic acid derived lactic acid or an oligomer, only a small portion of the slowly degrading elastomer residue (eg, segmented polyester) will remain. This remainder hot a large surface, and is believed to decompose faster than a mass-produced product.

The following examples show the blend of poly-lactic acid (PLA) with a segmented polyester, Hytrel ™, which is a block copolymer of hard polybutylene terephthalate crystal segments and soft, long chain polyether glycol segments. It is proved that poly-lactic acid melts compatible with this elastomer and the influence on its physical properties is shown.

D-lactide is a dlactate or cyclic dimer of D-lactic acid. Analogously, L-lactide is a cyclic dimer of! .- lactic acid. Meso D.L-Lactld is a cyclic dimer of D- and L-lactic acid. Racemic D-L-lactide consisting of a mixture of 50/60 D and u. L-lactide. If the term "D, L-lactide" is used herein only, then meso D, L-lactide or racemic D.L-lactide should be included Poly-lactic acid can be made from one or more or above mentioned substances.

Example 1D

A polylactide copolymer without the segmented polyester Hytrel ™ was prepared using the procedure of Example 1B of the second general embodiment of Serial No. 229,939 and tested for Izod impact strength. The results are shown in Table 1D. For comparison purposes, in Table 1B of the second general embodiment, Izod impact strength values are further compounded ratios of L-lactide to D, L-lactide.

Example 2D Into a 250 ml three-neck round bottom flask are placed 10.96 g of D ₁ L-LaKtId, 108.86 g of L-lactide and 5.27 g segmented polyester Hytrel ™

4056 (DuPont, a thermoplastic elastomer) weighed. Dor segmented polyester Hytrel ™ 4056 is a

Polyolayer elastomer with a low flexural modulus determined on a Shore D-Diirometer has a high Melt viscosity, a melt index of 7, a specific gravity of 1.17, a melting point of 334 ⁰ F, a Vicat Softening temperature of 234 "F and an extrusion tempera ture of 340 ° F to 400 ⁰ F. The piston is equipped with a mechanical Stirrer and an inlet and outlet for nitrogen equipped. The contents are heated in an oil bath. The segmented polyester Hytrel ™ dissolves in the molten lactides at 17O ⁰ C. Prepare a catalyst solution by dissolving 10 ml of tin (II) -

octoat in 60ml toluene and by distilling 10ml into the toluene. A portion of 100 microliters of the catalyst solution is injected into the solution of lactide and segmented polyester Hytrel ™. The mixture is stirred under nitrogen at 155 ^° C. for about 64 hours.

Viscosity increases dramatically and the mixture becomes cloudy. The product is tough and opaque. There were slides mil

a thickness of 8-9 mils by compression molding at 155 ⁰ C and determined the tensile strengths, as shown in Table 1D.

Plates of Vs inch thickness were compression molded and their Izod impact strength determined with a 2 pound pendulum. The Results are included in Table 1D, with the same polylactide copolymer from Example 1D without

segmented polyester Hytrel ™ and with the values of the so-called medium impact polystyrene, Example 7 D, are compared.

Example 3 D

800g of L-lactide and 202.3g of racemic D, L-lactide are prepared using 1.0ml of catalyst solution by means of analogous

Process as in Example 2 D copolymerizes with omission of the segmented polyester Hytrel ™. The lactide copolymer is

clear and colorless. In a separate polymerization, 104.0 g of L-lactide are melt polymerized using 100 microliters of catalyst. The polymer (L-PLA) is white, crystalline and easily cracked on impact.

An electrically heated two-roll mill is heated to 375 ⁰ F, then 8.4g segmented polyester Hytrel ™ and 19.2 g L-PLA made in strips on the roller. To this was added 172.4 g of lactide copolymer. The mixture mixes easily and

is removed from the rolls, compression molded and tested as in Example 2D. The values are shown in Table 1D.

Example 4 D

80g lactide copolymer of Example 3 D, 10g L-PLA of Example 3D, 10g segmented polyester Hytrel ™ 4056 are mixed on a two-roll mill as previously described in Example 3D. The mixture was tested as before and the values are included in Table 1D.

Example 5D '

Further, 100g of the mixture of Example 3D was blended with 20g segmented polyester Hytrel ™ 4056. The mixture was easily mixed on the roller and was obviously very compatible. The physical properties were determined as previously described and summarized in Table 1D.

Examples β D and 7 D For comparative controls, typical crystal polystyrene and medium-impact polystyrene were tested. The above results clearly indicate that polylactides can be modified for impact resistance. The mixtures

showed significantly higher Izod impact values than Kontioll-Krlstall polystyrene and slightly lower or equivalent impact strengths compared to medium impact polystyrene. Those skilled in the art will recognize that one can further improve the values of impact resistance in Table 1D by optimizing the level and type of impact modifier.

Since it has already been shown in the third general embodiment above that polylactides are compatible with

for many other compounds and thermoplastics, the impact modification modification of polylactides generally applies to blends of polylactides and elastomers that are blend compatible. Also, the

Those skilled in the art will recognize that the values in Table 1D can be improved if the blends are in contrast to compression molding

be processed by the injection molding process, since the former often causes orientation of the test specimens and consequently a strong improvement in impact resistance.

Comparisons of the physical properties of impact modified polylactides

example Composition, Ma .-% L-lactide 20 Hytrel "" ¹ Zugfestlgk. strain tangents Schlagblegefestigk. number lactide Copolymer homopolymer 0 0 psi ' "·" % module, psi nachlzod.ft-lb / '' ⁰ ' 8O ^WI 9.6 4.2 ^ln / 667 3.4 322679 0.3-0.4 1D 95.8 '·' 10.0 4.2 ^(h) 8636 3.1 359109 0.40 2D 8β, 2 ^(β1 7.9 10,0 ^lhl 7823 3.1 • 346502 0.51 3D 80.0 ^(gl 0 20.9 ^(hl - - _ 0.53 4D 71.2 ¹ » ¹ 0 0 - - - 0.61 5D 0 0 6118 3.2 267245 0.18 6D ^m 0 6090 4 - 0.7 7D « ¹

(a) DuPont Hytrel '4056, a thermoplastic polyester elastomer.

(b) ASTM D 882.7-16 mil film thickness.

(c) Molded test specimens.

(d) Control 90/10, L-D / L-lactide copolymer.

(e) 91/9, L-D / L-lactide copolymer. '

(f) Hytrel gel dissolved in lactide monomers prior to polymerization at 170 ° C

 Ig) 80/20, L-D / L-lactal copolymer.

(h) 2-Walzwerkmlschung at 185-190 ⁰ C.

(I) Control, krystal polystyrene, melt index 1.7.

Ij) Control, polystyrene with medium impact strength.

The compositions are useful thermoplastics prepared by conventional methods, e.g. B. extrusion and compression molding, can be processed as a melt.

For the mixtures, it is advantageous to use a physical mixture of poly-lactic acid of the formula I in which η is an integer between 75 and 10,000, and a polymer which consists of a segmented polyester. A usable composition is when the poly-lactic acid contains 50 to 99% by mass of the composition. A preferred composition has a poly-lactic acid content of 70-80% by weight.

Two embodiments of the general method of making the composition include (1) melt blending of PLA with a blend compatible polymer having improved impact resistance, e.g. a segmented polyester; and secondly, the solution mixture during the polymerization of PL A as in Example 2D, with segmented polyester Hytrel ™ dissolved in the PLA. The preferred lactic acid has the formula I. If desired, plasticizer may be added in appropriate amounts to the mixture selected from the group consisting of lactide monomers, lactic acid oligomers, lactic acid and mixtures thereof. The addition of plasticizer additionally provides only physical properties as treated in the first, second and third general embodiments above. A microscopic examination of the mixture of segmented polyester Hytrel ™ / poly-lactic acid revealed that the segmented polyester Hytrel ™ is present in a size of a few microns or less in the form of small spherical white areas. These white areas can be obtained by means of mixing conditions, e.g. Set time, speed of mixing and temperature. Therefore, for example, the polymer or polymers added to the poly-lactic acid must generally have a small heterogeneous size of the white areas below 10 microns, and may be submicroscopic in size or dissolved in the poly-lactic acid. In addition, the impact modifier must be elastomeric.

While not wishing to be bound by any particular theory, it is believed that the present invention provides a durable base of poly-lactic acid having intimately mixed microscopic white areas of segmented polyester Hytrel ™, which acts as a crack stopper the latter being a poly-lactic acid compatible thermoplastic elastomer.

For this purpose, the impact modifier must be elastomeric and intimately bonded in the lactic acid in the form of a discrete heterogeneous phase. The added polymer, the impact modifier, may be a thermoplastic elastomer or a crosslinked rubber to achieve the elastic behavior. Examples are natural rubber and styrene-butadiene copolymers.

Examination of a five month water-immersed material made it brittle compared to Materiel, which was not exposed to water. In addition, the water became acidic, showing a splitting of the poly-lactic acid to lactic acid. It was also evident that poly-lactic acid alone decomposed faster than the blend of segmented polyester Hytrel ™ / poly-lactic acid. Thus, one can also use segmented polyester Hytrel ™ to retard the degradation rate of poly-lactic acid.

To improve compatibility, one may also add a third component that is compatible with the others discussed above. Thus, with little compatibility of the poly-lactic acid and the impact modifier, a third component can be added to improve compatibility. This third component is usually added where it is individually compatible with the other two and where the other two, poly-lactic acid and the impact modifier, are not very compatible. This works by increasing the interfacial bond between poly-lactic acid and the elastomeric impact modifier. What is surprising, however, is the wide latitude in the other types of polymers, both polar and nonpolar. This can be related to the third general embodiment. The compositions mentioned hler can be processed by melt fabrication into useful articles of manufacture, for. As containers, Eßutensilien, trays, plates, cups, individual service plates, syringes, medical bowls u. The compositions are particularly suitable for articles which are used only once or have a short life before being discarded.

While the invention has been described above with reference to various specific examples and embodiments, it should be understood that the invention is not limited to such illustrated examples and embodiments and that it can be variously applied within the scope of the claims set forth below.

Claims (46)

An environmentally biodegradable composition which can be used as a substitute for thermoplastic polymer compositions, characterized by containing a polymer of the following formol: - C- II plasticized with a plasticizer selected from a group consisting of lactide, oligomers of lactic acid, oligomers of lactide and their mixture, where η is the number of repeating structural units and η is an integer between 150 <η <20,000 and wherein the unoriented composition has a tensile strength of 300 to 20,000 psi, a breaking elongation of 50 to 1,000% and a tangent modulus of 20,000 to 250,000 psi. 2. A composition according to claim 1, characterized in that the polymer is derived from monomers of the lactide selected from a group consisting of L-lactide, D-lactide, meso, D, L-lactide and mixtures thereof. 3. The composition according to claim 1, characterized in that the oligomers of lactic acid or of lactide the formula -C- O) m in which m is an integer: 2 <m <75. A composition according to claim 1, characterized in that it further contains additional plasticizer dispersed in the composition selected from a group of monomers consisting of D-lactide, L-lactide, meso D, L-lactide, racemic D, L-lactide and mixtures thereof so that at least a portion of the dispersed monomer is stereochemically different from that used to make the polymer. The composition of claim 1, further characterized in that it contains an oligomer dispersed in the composition which is not produced during polymerization of the polymer. 6. A process for the preparation of an environmentally biodegradable composition of poly-lactic acid, characterized in that it consists of: a) preparation of the lactide monomer and the catalyst; b) polymerizing the monomer of step (a) to form a polymer at a low enough temperature to allow interruption of the reaction to complete the polymerization; c) control of the monomer level in step (b) to determine the remaining monomer content and d) interrupting the polymerization of step (b) to complete the reaction at a monomer level determined in step (c) such that unreacted monomer is contained in a predetermined amount in association with the polymer. 7. The method of claim 6, further characterized in that e) the incorporation of additional plasticizer is included in the composition, wherein the plasticizer is further selected from the group consisting of L-lactide, D-lactide, meso D, L-lactide, lactic acid, oligomers of lactide, oligomers of lactic acid and their mixtures. The process of claim 7, further characterized in that it includes the selection of a monomer that is stereochemically different from that selected to produce the polymer. 9. A process for the preparation of a biodegradable composition of poly-lactic acid, characterized in that it a) the preparation of the lactide monomer and the catalyst; b) polymerizing the monomer of the solution of step (a) to form a polymer and c) incorporating a plasticizer into the polymer of step (b), wherein the plasticizer is selected from the group consisting of D-lactide, L-lactide, D, L-lactide, * oligomers of lactic acid, oligomers of lactide and their mixtures. A method of biodegrading a thermoplastic polymer composition consisting of first orientable polymer structural units in the environment, characterized by: Replacement of the first polymer structural units with a second orientable polymer having an unoriented tensile strength of 300 to 20,000 psi, an elongation at break of 50 to 1,000%, and a tangent modulus of 20,000 to 250,000 psi, the second polymer being lactic acid of the formula: ^CI ? 3 f - 8 - 0 Jn wherein η is the number of repeating structural units and η is an integer of 150 η 20000 and which is plasticized with a plasticizer selected from a group consisting of lactide, oligomers of lactic acid, oligomers of lactide and mixtures thereof , A method of biodegrading a polymer composition consisting of first orientable polymer structural units in the environment, characterized by: Replacement of the first polymer structural units with a second orientable polymer having an unoriented tensile strength of 300 to 20,000 psi, an ultimate elongation of 50 to 1000%, and a tangent modulus of 20,000 to 250,000 psi, the second polymer being lactic acid of the formula «3 y - C - 0 yes wherein η is the number of repeating structural units and η is an integer of 150 <η <20,000 and is plasticized with a plasticizer selected from the group consisting of lakxid, oligomers of lactic acid, oligomers of lactide and their mixtures are obsolete. 12. An environmentally biodegradable composition, characterized in that it can be used as a substitute for polystyrene, characterized in that it poly (lactic acid) units of the formula CH wherein η is an integer between 75 and 10,000 and the alpha carbon is a mixture of L and D configurations predominantly of either D or L moieties, the polymer being selected from L-Lai'.tid or D Lactide of 85 to 95 parts by weight and D, L-lactide of 15 to 5 parts by weight, the unoriented polymer having a tensile strength of at least 5000 psi, a tangent modulus of at least 200,000 psi, and the dispersed plasticizer having from 0.1 to 5% by mass. is available. The composition of claim 12, further characterized by containing in the composition dispersed monomer selected from the group consisting of D-lactide, L-lactide, meso DL-lactide, racemic D, L-lactide and their Mixtures exist, so that at least a portion of the dispersed monomer stereochemically different from the monomer used to prepare the polymer. 14. The composition of claim 12, further characterized in that it contains oligomer which differs from that obtained during the polymerization of the polymer. An environmentally biodegradable composition useful as a replacement for polystyrene, characterized in that it comprises mixtures of a physical mixture of a) a first polymer with poly-lactic acid units of the formula - C - C} n wherein η is an integer between 75 and 10,000 and the alpha carbon is a mixture of L and D configurations overweight either D or L moieties and
b) contains a lactide homopolymer of D-lactide or L-lactide, wherein the unoriented composition has a tensile strength of at least 5000 psi and a tangent modulus of at least 200,000 psi as well as dispersed plasticizer. 16. A composition according to claim 15, further characterized in that the dispersed plasticizer is contained at 0.1 to 5 wt%. 17. A composition according to claim 15, further characterized in that the polymerized lactic acid is present in a proportion of 98 to 75% by weight and the lactide homopolymer in a proportion of 2 to 25%. The composition of claim 15, further characterized by containing a plasticizer selected from the group consisting of D-lactide, L-lactide, meso D, L-lactide, lactic acid, lactidoligomor, lactic acid oligomer and mixtures thereof. Composition according to Claim 15, characterized in that it contains plasticizer selected from a group of monomers selected from the group consisting of D-lactide, L-lactide, meso D, L-lactide, racemic D, LL-ktid and mixtures thereof such that at least a portion of the dispersed monomer is stereochemically different from that for the preparation of the first polymer and homopolymer. 20. A process for the preparation of the composition according to claim 12, characterized by: a) Mixing with a catalyst, heating and melting of L-lactide or D-lactide monomer and D, L-lactide monomer, wherein the L-lactide monomer or D-lactide monomer with 85 to 95 parts by mass and the D, L-Lactidmonomer with 15 bis 5 parts by mass is present and form an intimate solution; b) polymerizing the solution of step (a) and c) treatment of the polymer of step (b) to improve its properties. 21. The method according to claim 20, characterized in that the treatment comprises the addition of a D-lactide or L-lactide copolymer by mixing. A method according to claim 20, characterized in that the treatment comprises adding a nucleating agent and a D-lactide or L-lactide polymer by mixing. 23. The method according to claim 20, characterized in that the treatment a) the control of the polymerization stage (b) by adding a chain transfer agent and b) includes the addition of nucleating agents and a D-lactide or L-lactide homopolymer by mixing. A method according to claim 20, further characterized by comprising a treatment step in the form of adding an additional plasticizer to the composition, wherein the plasticizer is selected from the group consisting of D-lactide, L-lactide, Meso D, L Lactide, lactic acid, lactide oligomer, lactic acid oligomer and mixtures thereof. Process according to Claim 20, characterized in that, if a monomer is chosen, at least one monomer differs stereochemically from the monomer (s) chosen in step (a). 26. A method of rendering a thermoplastic polymer composition consisting of first orientable polystyrene structural units biodegradable in the environment, characterized by: Replacing the polystyrene structural units with a second orientable polymer having an unoriented tensile strength of at least 5000 psi and a tangent modulus of at least 200,000 psi and dispersed plasticizer of 0.1 to 5 mass%, said second polymer comprising polylactic acid units of the formula - C - O) n contains. Here, η is an integer between 75 and 10,000, and the alpha carbon is a mixture of L and D configurations with an overt weight of either D or L moieties. wherein the polymer is made of L-lactide or D-lactide of 85 to 95 parts by mass and D, L-lactide of 15 to 5 parts by mass. 27. An environmentally degradable composition, characterized by containing mixtures of a physical mixture of: a) a poly-lactic acid and b) a polymer selected from a group consisting of a polymer of ethylene terephthalate a polymer or copolymer of styrene, ethylene, propylene, vinyl chloride, vinyl acetate, alkyl methacrylate, alkyl acrylate and their physical mixtures. 28. A composition according to claim 27, characterized in that the percentage mass ratio of the poly-lactic acid to the selected polymer is between 99: 1 and 1:99. 29. A process for the preparation of a composition according to claim 27, characterized in that it a) the preparation of a poly-lactic acid; b) the selection of a polymer from a group consisting of a polymer of ethylene terephthalate, a polymer or copolymer of styrene, ethylene, propylene, vinyl chloride, vinyl acetate, alkyl methacrylate, alkyl acrylate and their physical mixtures, and c) the mixture of the polymer of steps a and b includes. The composition of claim 27 further characterized by containing a plasticizer selected from the group consisting of D-lactide, L-lactide, meso D, L-lactide, lactic acid, lactide oligomer, lactic acid oligomer and mixtures thereof. 31. A process for producing an environmentally degradable composition, characterized by a) Preparation of a lactide monomer selected from a group consisting of D-lactide, L-lactide, meso D, L-lactide, racemic D, L-lactide and mixtures thereof; B) selecting a polymer from a group consisting of a polymer of ethylene terephthalate, a polymer or copolymer of styrene, ethylene, propylene, vinyl chloride, vinyl acetate, alkyl methacrylate, alkyl acrylate and their physical mixtures; c) mixing and heating the lactide selected under (a) and the polymer selected under (b) under adapted conditions in order to melt the lactide and at least partially dissolve the polymer and d) polymerizing the lactide in the mixture of step (c) to obtain a mixture of polylactide and polymer. 32. The method of claim 31, further characterized by the step e) includes molding the mixture into a self-supporting structure. 33. The process of claim 31, further characterized by including controlling the remaining monomer portion and controlling the polymerization of step (d) to obtain a mixture containing a residual monomer. The method of claim 31, further characterized by including adding plasticizer to the mixture after polymerization selected from a group consisting of lactide monomer, lactide oligomer, oligothioic acid oligomer, lactic acid, and mixtures thereof. 35. An environmentally degradable composition, characterized by containing mixtures of physical mixtures of: a) a poly-lactic acid and b) a blend-compatible polymer which imparts improved impact resistance to the poly-lactic acid. A composition according to claim 35, characterized in that the poly-lactic acid contains from 50 to 99% by mass of the composition. 37. A composition according to claim 35, characterized in that it is the mixed-compatible polymer is a segmenlierten polyester. 38. A composition according to claim 37, characterized in that the blend compatible polymer is a block copolymer of hard crystalline segments of polybutylene terephthalate and soft long chain segments of polyether glycol. 39. A process for the preparation of a composition according to claim 35, characterized in that it a) the preparation of a poly-lactic acid; b) the selection of a blend-compatible polymer which increases the impact strength and c) the mixture of the polymer of steps (a) and (b) includes. 40. The method according to claim 39, characterized in that a segmented polyester is selected. 41. The method according to claim 39, characterized in that a block copolymer of hard crystalline segments of polybutylene terephthalate and soft long chain segments of polyether glycols or natural rubber and styrene butadiene copolymers is selected. 42. A process for the preparation of the composition according to claim 35, characterized by: a) mixing one or more lactide (s) selected from a group consisting of D-lactide, L-lactide, D, L-lactide and mixtures thereof with a blend compatible polymer which imparts improved impact resistance to the composition; b) heating and dissolving the mixture-compatible polymer in the LaUtid (s) of step (a) to prepare a solution c) polymerizing the lactide (s) in the solution. 43. The method of claim 42, further characterized by further including the step of processing the composition by melt processing into useful forms. 44. The method of claim 42, further characterized by including selecting a mix compatible polymer containing a segmented polyester. 45. The method of claim 42, further characterized by including selecting a blend compatible polymer from a group consisting of a block copolymer of hard crystalline segments of polybutylene terephthalate and soft long chain segments of polyether glycol and natural rubber and styrene butadiene copolymers or mixtures thereof , 46. The method of claim 35, further characterized in that e) contains the addition of a plasticizer to the mixture selected from a group consisting of lactic acid monomer, lactide oligomer, lactic acid oligomer, lactic acid and mixtures thereof.