Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1997-11-17
1999-12-21
Nutter, Nathan M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
5283291, 435 711, 435132, 435135, 435136, 435128, 435155, C08K 500, C08K 517, C08L 6704
Patent
active
060050667
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCES TO RELATED APPLICATIONS
This application is the national phase entry of International patent application PCT/GB95/01375, filed Jun. 13, 1995, and claims priority from Great Britain patent application no. 9411792.6, filed on Jun. 13, 1994.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
THIS INVENTION relates to a polymer composition and in particular to a composition comprising an aliphatic polyester and a stabiliser against thermal decomposition.
2. Description of Related Art
Examples of such polyesters have become available commercially as the result of the development of microbiological processes for making them. The earliest example, PHB, was difficult to melt-process owing to low stability at its melting temperature. Corresponding copolyesters melt at a lower temperature. In addition, synthetic aliphatic polyesters of the head-to-head tail-to-tail type such as polybutylenesuccinate and of the head-to-tail type such as polylactic acid, polycaprolactone and synthetic polyhydroxyalkanoates, have recently become available. There is room for improvement in stability, such that greater freedom in choosing processing conditions and/or a wider range of end-uses could become available. This has recently arisen using the stereospecific polyesters produced microbiologically.
BRIEF SUMMARY OF THE INVENTION
It has now been found that compositions comprising such polyesters (which term includes homopolyesters, copolyesters and mixtures thereof) and one or more polyfunctional compounds of a defined class show substantial advantages.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIGS. 1 to 5 of the accompanying drawings show the DSC results obtained in respectively runs 1 to 5 of the Example.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention a polymer composition comprises an aliphatic
polyester and at least one compound of general formula I:
Hydrocarbon group A is preferably aliphatic, preferably containing a hydrocarbon chain of up to 8 carbon atoms with up to 6 carbon atoms in any side chain(s).
Groups R.sup.1 are suitably selected from hydroxy, amino, thiol and derivatives thereof. Such an amino group preferably is primary or is secondary or tertiary carrying one or two lower alkyl (C.sub.1-6) groups. It may be present in part in protonated form, especially in presence of weak acid such as carboxylic, for example in a zwitterion. Suitable derivatives are esters or amides, as mentioned further below. In such ester or amide the linkage to A is through O or N, respectively. Groups R.sup.1 in any one such compound may be the same or different.
Groups R.sup.2 preferably include at least one carboxylic acid and/or carboxylic amide and/or quaternary onium group, for example ammonium quaternised with lower alkyl, especially methyl. In such amide the carbon of the carboxylic group is linked to A directly. Group R.sup.2 may be the same or different in any one such compound.
The numbers a and b preferably total 2 to 4.
The compound is preferably an amino carboxylic acid. Any one or more of the "essential" amino acids may be used, or corresponding acids of different chirality or in racemic form. Alternatively synthetic amino acids may be used. Preferably there is at least one group R.sup.1 additional to the CO.sub.2 H and .beta.-amino group. Thus it is preferably for example asparagine, aspartic acid, arginine, cysteine, glutamic acid, glutamine, histidine, lysine, ornithine, serine, threonine, tryptophan or tyrosine or a mixture of two or more of these possibly with other amino acids.
When R.sub.2 is a quaternary onium group a preferred compound is a quaternised alkanolamine, for example choline or a derivative thereof, especially a phosphatidyl choline.
If, instead of or in addition to the free compound, a derivative thereof is present, R.sup.1 may be for example an ester or amide derived from a C.sub.1-6 aliphatic carboxylic or carbonic or carbamic or phosphoric (including phosp
REFERENCES:
patent: 4477654 (1984-10-01), Holmes et al.
patent: 5076983 (1991-12-01), Loomis et al.
Lehrle Roy Sherwin
Williams Robert John
Bond Gary M.
Monsanto Company
Nutter Nathan M.
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