Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1999-02-25
2000-09-12
Nutter, Nathan M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
525 542, 525 5422, 525 5424, 525 5426, 525 543, C08B 3104, C08L 306
Patent
active
061179256
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for preparing thermoplastically processible starch polymer mixtures or starch derivative mixtures according to the preamble of claim 1 and to a number of uses.
The present invention in particular relates to thermoplastically processible transesterification products of starch or derivatives thereof with, for example, lactones, esteramides, fatty acids, etc. and/or polyesters or other biologically degradable hydrophobic polymers and mixtures of transesterification products with the above-mentioned polymers. Their use is based on the fact that numerous types of starch, as macromolecular raw materials, are cheaper than the known thermoplastic materials.
Additionally, the present invention relates to processes for preparing the transesterification products of starch or derivatives, such as, in particular, starch acetates.
2. The Relevant Technology
Thermoplastically processible blends of starch have been described in WO 90/05161. Thermoplastically processible blends of starch, of softeners and of water-insoluble polymers display only limited uptake of water and have useful mechanical strength, but they are not storable at any level of surrounding humidity in the long term.
In addition, in JP 05 125 101, transesterification products of starch have been described which melt in the temperature range of from 150 to 170.degree. C.; however, these products are unsuitable for wide use owing to their water uptake from the surrounding air and their poor mechanical properties. The preparation of these products by the known processes is prohibitive for wide use.
BRIEF SUMMARY OF THE INVENTION
The present invention, accordingly, proposes mixtures of transesterification products of starch or derivatives thereof with low-molecular-weight lactones, esteramides, fatty acids, etc., and oligomeric esters, polyesters and other hydrophobic biologically degradable polymers. At the phase boundaries between the transesterification products and, for example, the polyester, these mixtures show no preferred cracking on deformation and good stability of the mechanical properties on storage, and additionally they do not release any low-molecular-weight substances on contact with moisture.
The present invention additionally relates to a process for preparing transesterification products of starch or derivatives, such as, in particular, starch acetates with, for example, lactones and/or polyesters in the presence of transesterification catalysts.
Transesterification products of starch with low-molecular-weight lactones, such as dilactide, caprolactone (CL) or diglycolide are known. Also known are transesterification products of starch and polyesters, such as polycaprolactone (PCL). The polyester component may additionally be a copolyester, for example constructed from terephthalic acid, adipic acid, ethylene glycol and butanediol or from oligomeric esters of ethylene glycol and terephthalate, transesterified with caprolactone. However, the polyesters used have to be meltable in a temperature range of from 60 to 200.degree. C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention describes transesterification products of starch or of starch derivatives which can be processed with suitable polyesters and other biologically degradable hydrophobic polymers to give thermoplastically processible mixtures having useful properties. Such mixtures consist of a disperse phase of the esterification or transesterification product of the starch and a continuous phase of the polyester or the hydrophobic, biologically degradable polymer. To be able to achieve suitable mechanical properties and storage stability of the mixture at various levels of surrounding humidity, macromolecular components are required whose molecules bridge the phase boundaries between the disperse and the continuous phase. If such so-called compatibilizers are not incorporated into the mixture in sufficient amounts, thermoplasts having set breaking points at the p
REFERENCES:
patent: 5540929 (1996-07-01), Narayan et al.
Bio-Tec Biologische Naturverpackungen GmbH & Co. KG
Nutter Nathan M.
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