Biodegradable polymers, the preparation thereof and the use ther

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

1997-05-12

1998-10-06

Acquah, Samuel A.

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

Synthetic resins

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

528272, 528295, 528296, 528302, 528307, 528308, 5283086, 525444, 525445, 525450, 525451, C08F 2000, C08G 6312

Patent

active

058177213

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to biodegradable polyesters Q1 with a molecular weight (M.sub.n) in the range from 6000 to 60,000 g/mol, a viscosity number in the range from 30 to 350 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyester Q1 at 25.degree. C.) and a melting point in the range from 50.degree. to 170.degree. C., obtainable by reacting a mixture essentially comprising mixture essentially comprising thereof, mixtures thereof, and individual mole percentages is 100 mol %, and -C.sub.6 -alkanediols and C.sub.5 -C.sub.10 -cycloalkanediols, where the molar ratio of (b1) to (b2) is chosen in the range from 0.4:1 to 1.5:1, the range from 5000 to 50,000 g/mol, a viscosity number in the range from 30 to 350 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyester P1 at 25.degree. C.) and a melting point in the range from 50.degree. to 170.degree. C., and with the further proviso that from 0 to 5 mol %, based on the molar quantity of component (b1) employed, of a compound D with at least three groups capable of ester formation are employed to prepare the polyester P1, of compound D.
The invention furthermore relates to other 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 displaying 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.
According to EP-A 534,295, a chain extension can also be achieved advantageously by reaction with divinyl ethers.
WO 92/13019 discloses copolyesters based on predominantly aromatic dicarboxylic acids and aliphatic diols, where at least 85 mol % of the polyester diol residue comprises a terephthalic acid residue. The hydrophilicity of the copolyester is increased, and the crystallinity is reduced by modifications such as the incorporation of up to 2.5 mol % of metal salts of 5-sulfoisophthalic acid or short-chain ether diol segments such as diethylene glycol. This is said in WO 92/13019 to make the copolyesters biodegradable. However, the disadvantage of these copolyesters is that biodegradation by microorganisms have not been demonstrated, on the contrary only the behavior toward hydrolysis in boiling water or, in some cases, also with water at 60.degree. C. has been 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 terephth

REFERENCES:
patent: 5097005 (1992-03-01), Tietz
patent: 5247049 (1993-09-01), Groll et al.
patent: 5593778 (1997-01-01), Kondo et al.
patent: 5616657 (1997-04-01), Imamura et al.
Derwent Abstracts WPI, Week 9231, AN 92-256555 (English abstract of JP-A 04175375. Nature, vol. 270, pp. 76-78, 1977.
Tokiwa et al., J. of Appl. Pol. Sci., vol. 26, pp. 441-448, 1981.
Witt et al., Handout of a Poster, International Workshop of the Royal Inst. of Tech., Stockholm, Sweden, pp. 21-23, Apr. 1994.

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