Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1997-06-16
1998-06-02
Acquah, Samuel A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528176, 528212, 528361, 525450, 524714, C08G 6306
Patent
active
057601704
DESCRIPTION:
BRIEF SUMMARY
POLYESTER COMPOSITION
THIS INVENTION relates to a polyester composition and in particular to a composition comprising an aliphatic polyester and a plasticiser.
Examples of such polyesters have become available commercially as the result of developing microbiological processes for making them. The earliest example, PHB, was difficult to melt-process owing to low thermal stability at its melting temperature. Corresponding copolymers melt at a lower temperature. When such polyester is used for making plastics shaped articles, it may be necessary to formulate it with a plasticiser in order to obtain desired mechanical properties. Many plasticising compounds have been proposed for this duty, but there is room for improvement in the mechanical properties obtained and their permanence.
It has now been found that compositions comprising such polyesters (which term is herein to include homopolyesters, copolyesters and mixtures thereof) and one or more phenolic compounds of a defined class show substantial advantages.
ACCORDING TO THE INVENTION in its first aspect a polymer composition comprises consisting of repeating units of formula --O--C.sub.m H.sub.n --CO-- in which n=2m and units with m=3 and m=4 with respectively a C.sub.1 and C.sub.2 side group on the carbon atom next to oxygen in the polymer chain are copolymerised together, m being 3 in 70-95 mol percent of such units; and
In the alkyl phenol there is preferably at least one alkyl group containing a chain of at least 2 and suitably up to 20 carbon atoms. Preferably at least one such alkyl group contains at least one tertiary carbon atom, for example linked to 2 side substituents other than hydrogen, at least one of which atoms is carbon. The chain preferably carries at least 2 and suitably up to 6 hydrocarbon side substituents, and these are preferably C.sub.1-6, especially methyl. A or the tertiary carbon atom is preferably adjacent to or within 4 carbon atoms of the phenol nucleus. On any of the tertiary carbon atoms, any side substituent atom that is not carbon is preferably oxygen.
The alkyl phenol is preferably "hindered", that is, rotation of the alkyl group is inhibited by collision with a nuclear substituent (especially OH or O-alkyl) ortho to the alkyl group or is prevented by a ring-forming linkage of the alkyl group to the phenolic nucleus.
The alkyl phenol preferably contains also at least one hydrocarbonoxy group, preferably para to the phenolic OH group. Suitably the hydrocarbonoxy group is C.sub.1-6 alkoxy.
Particular examples of suitable alkyl phenols are:
Instead of the free alkyl phenol, an ester thereof may be present, for example a C.sub.1-6 carboxylic ester. It is believed that such ester is an example of a precursor decomposable to the alkyl phenol during processing and/or ageing of the polyester. Likewise, a thermal and/or oxidative reaction product of the alkyl phenol, such as may result from processing and/or ageing, may be added instead of free alkyl phenol. A particular example is 2,2'-dihydroxy-5,5'-dimethoxy-3,3'-di-tert-butylbiphenyl, an oxidation product of 3-tert-butyl-4-hydroxyanisole.
The defined class of alkyl phenols includes compounds effective as anti-oxidants, for example in foods, oils and polymer systems. These may be used and are believed to be preferable, especially if they are harmless to life and/or are biodegradable.
The invention includes: article; and/or whatever conversion product has been formed from it.
The polyester is preferably capable of a relatively high level of crystallinity, eg over 30%, especially 50-90%, in the absence of additives.
The molecular weight Mw of the PHA is for example up to eg 2.times.10.sup.6.
In PHAs having m=3 and m=4 there may be very small, typically fractional, percentages of units having higher values of m. PHA consisting essentially of m=3 units is poly-3-R-hydroxybutyrate (PHB), and PHA consisting of m=3 and 4 units is polyhydroxybutyrate-co-valerate (PHBV).
The PHA can be a product of fermentation, especially a process in which a microorganism lays down PHA during normal
REFERENCES:
Database WPI, Section Ch, Week 9441, Derwent Publications Ltd., London, GB; Class A23, AN 94-329584 & JA, A, 06 255 039, Sep. 13, 1994.
Blanshard John Michael Vivian
Fujita Shuzo
Hammond Timothy
Acquah Samuel A.
Bond Gary L.
Monsanto Company
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