Biologically degradable polyester, materials made from the polye

Details Biologically degradable polyester, materials made from the polye Biologically degradable polyester, materials made from the polye

1998-08-14

2000-11-21

Cooney, Jr., John M.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

528272, 528288, 528302, C08G 1834

Patent

active

061504904

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The invention relates to biodegradable copolyesters of aliphatic and aromatic dicarboxylic acids with high molecular weights (in particular in the form of a material or substance to be processed further) and materials consisting of the polyester and a method of production.


DESCRIPTION OF THE RELATED ART

In view of the increasingly problematic waste situation, thermoformable polymeric materials have been developed in recent years which can be decomposed biologically by microorganisms. Although initial batches of mixtures of conventional olefinic polymers with starch (Krupp et al in Environ. Sci. Technol., 26 (1992) 193-1981) exhibited good application properties, they proved to be only partially degradable since only the starch content was metabolised by microorganisms. Biodegradable materials which are obtained directly or after suitable modification (Utz et al., Untersuchungen zum Einsatz bioabbaubarer Kunststoffe im Verpackungsbereich--investigations on the use of biodegradable plastics in the packaging sector (1991), ), BMFT research report no. 01-zv 8904) from biogenic polymers are usually fully biodegradable but frequently exhibit serious drawbacks with respect to processing and use. Plasticised starch materials, for example, are thus not resistant to water. However, the limited variability and reproducibility of the material properties must, above all, be regarded as major disadvantages of such natural materials.
A solution to these problems can be achieved by using synthetic polymers. In this respect, polymers exhibiting hetero atoms in their main chain have, in general, proved to be potentially biodegradable. It is known that aliphatic polyesters, in particular, are metabolised by microorganisms within relatively short periods of time (Witt et al. in Makromol. Chem. Phys., 195 (1194) 793-802); however, such polyesters frequently exhibit only moderate thermal and mechanical properties. The aliphatic polyester polycaprolactone, for example, has a melting point of only approximately 60.degree. C., making it unsuitable for various applications. It is known that an improvement in the mechanical processing and application properties of polyesters and polyamides can be achieved by increasing the molecular weight by coupling them with diisocyanates, bisoxiranes or peroxides (DE A 1 495 714.3, DE A 2 011 678.3). Such a modified aliphatic polyester which is referred to as being biodegradable, is described in EP A 0 572 256. In the case of this material, diisocyanates have been added in quantities of 0.1 to 5%. The thermal properties of the aliphatic polyester, however, remain largely unaffected by such a modification. Apart from such polyesters, the use of aliphatic polyester urethanes containing up to 25% urethane segments, as biodegradable substances, is also described (EP A 0 593 975).
It is also known that the material properties of aliphatic polyesters can be improved dramatically if part of the aliphatic dicarboxylic acid is substituted by aromatic carboxylic acids. A copolyester based on 1,4-butane diol and terephthalic acid is thus described (EP A 0 007 445), 10 to 30 mole % of the terephthalic acid being replaced by a mixture of adipic acid, glutaric acid and succinic acid. These mixed polymers are processed into moulded parts by injection moulding or extrusion, but are not biodegradable. Aliphatic/aromatic copolyesters with terephthalic acid contents of 40 to 85 mole % have not been described as materials for further processing but for use as melt adhesives or coating agents in powder form (EP A 0 028 687), the biodegradability not being discussed in further detail.
In German patent application (1) 95 08 737.2 it was shown that it is possible to produce random copolyesters from aliphatic dicarboxylic acids and terephthalic acid and various aliphatic dicarboxylic acids and terephthalic acid as well as various aliphatic diols, which copolyesters exhibit satisfactory processing and application properties and, on the other hand, are biodegradable. An essential structural criterion o

REFERENCES:
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patent: 5310782 (1994-05-01), Takiyama et al.
Josef Augusta et al., "A Rapid Evaluation Plate-Test For The Biodegradability of Plastics", Applied Microbiology and Biotechnology, Springer-Verlag (1994) pp. 673-678.
Uwe Witt et al., "Synthesis, Properties and iodegradability of Polyesters Based on 1,3-Propanediol", Macromol. Chem. Phys. 195, 793-802 (1994).

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