Biodegradable polymers, the preparation thereof, and the use the

Details Biodegradable polymers, the preparation thereof, and the use the Biodegradable polymers, the preparation thereof, and the use the

1997-08-14

1999-08-10

Short, Patricia A.

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

525411, 525444, 525448, 528293, 528294, 528296, 528301, 528302, C08G 63672, C08G 6391

Patent

active

059360453

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to biodegradable polyether esters obtained by reacting a bisoxazoline C1 with a polyether ester such as P1 obtainable by reacting a mixture essentially comprising thereof, mixtures thereof, and consisting of C.sub.2 -C.sub.6 -alkanediols and C.sub.5 -C.sub.10 -cycloalkanediols, functionalities of the formula I thereof, 1.5:1, with the proviso that the polyether ester P1 has a molecular weight (M.sub.n) in the range from 5000 to 80,000 g/mol, a viscosity number in the range from 30 to 450 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyether ester P1 at 25.degree. C.) and a melting point in the range from 50 to 200.degree. C., and with the further proviso that from 0 to 5 mol%, based on the molar quantity of component (a1) employed, of a compound D with at least three groups capable of ester formation are employed to prepare the polyether ester P1, and the further proviso that the polyether ester P1 has both hydroxyl and carboxyl end groups, with the molar ratio of carboxyl end groups to hydroxyl end groups being chosen to be greater than one.
The invention furthermore relates to polymers and biodegradable thermoplastic molding compositions as claimed in the dependent claims, processes for the preparation thereof, the use thereof for producing biodegradable moldings and adhesives, biodegradable moldings, foams and blends with starch obtainable from the polymers and molding compositions according to the invention.
Polymers which are biodegradable, ie. decompose under environmental influences in an appropriate and demonstrable time span have been known for some time. This degradation usually takes place by hydrolysis and/or oxidation, but predominantly by the action of microorganisms such as bacteria, yeasts, fungi and algae. Y. Tokiwa and T. Suzuki (Nature, 270, (1977) 76-78) describe the enzymatic degradation of aliphatic polyesters, for example including polyesters based on succinic acid and aliphatic diols. groups (urethane units). The copolyesters of EP-A 565,235 are obtained by reacting a prepolyester, which is obtained by reacting essentially succinic acid and an aliphatic diol, with a diisocyanate, preferably hexamethylene diisocyanate. The reaction with the diisocyanate is necessary according to EP-A 565,235 because the polycondensation alone results only in polymers with molecular weights such that they display unsatisfactory mechanical properties. A crucial disadvantage is the use of succinic acid or ester derivatives thereof to prepare the copolyesters because succinic acid and derivatives thereof are costly and are not available in adequate quantity on the market. In addition, the polyesters prepared using succinic acid as the only acid component are degraded only extremely slowly.
WO 92/13020 discloses copolyether esters based on predominantly aromatic dicarboxylic acids, short-chain ether diol segments such as diethylene glycol, long-chain polyalkylene glycols such as polyethylene glycol (PEG) and aliphatic diols, where at least 85 mol% of the polyester diol residue comprise a terephthalic acid residue. The hydrophilicity of the copolyester can be increased and the crystallinity can be reduced by modifications such as incorporation of up to 2.5 mol% of metal salts of 5-sulfoisophthalic acid. This is said in WO 92/13020 to make the copolyesters biodegradable. However, a disadvantage of these copolyesters is that biodegradation by microorganisms was not demonstrated, on the contrary only the behavior towards hydrolysis in boiling water was carried out.
According to the statements of Y. Tokiwa and T. Suzuki (Nature, 270 (1977) 76-78 or J. of Appl. Polymer Science, 26 (1981) 441-448), it may be assumed that polyesters which are essentially composed of aromatic dicarboxylic acid units and aliphatic diols, such as PET (polyethylene terephthalate) and PBT (polybutylene terephthalate), are not enzymatically degradable. This also applies to copolyesters and copolyether esters which contain blocks composed of aro

REFERENCES:
patent: 3763079 (1973-10-01), Fryd
patent: 5171308 (1992-12-01), Gallagher
patent: 5292783 (1994-03-01), Buchanan

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