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US 4,477,654 AGranted
3-Hydroxybutyrate polymers
AssigneeImperial Chemical Industries PLC
InventorsPaul A. Holmes, Stephen H. Collins, Leonard F. Wright
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AssigneeImperial Chemical Industries PLC
InventorsPaul A. Holmes, Stephen H. Collins, Leonard F. Wright
Estimating the term…
High molecular weight copolymers containing 3-hydroxybutyrate residue, i.e. units of the formula --O.CH(CH.sub.3).CH.sub.2.CO-- and up to 50 mole % of residues of other hydroxy acids, viz units of the formula --O.CR.sup.1 R.sup.2.(CR.sup.3 R.sup.4).sub.n.CO-- where n is 0 or an integer and, if n=1 and R.sup.2, R.sup.3, and R.sup.4 =H, R.sup.1 is not methyl. The copolymers are made microbiologically: for part of the cultivation the micro-organism is under conditions such that polymer is accumulated, e.g. by limitation of a nutrient, e.g. nitrogen source, required for growth but not polyester accumulation. For at least part of this period of polymer accumulation the substrate is an acid or a derivative thereof that gives the comonomer units. Proprionic acid, which gives polymers where n=1, R.sup.2 =R.sup.3 =R.sup.4 =H and R.sup.1 =C.sub.2 H.sub.5, is the preferred acid.
Copolymers having a weight average molecular weight above 10,000 and containing repeat units
Copolymers having a weight average molecular weight above 10,000 and containing at least 50 mol % of repeat units
A process for the production of a thermoplastic polyester wherein a micro-organism that is capable of accumulating a polyester is cultivated in an aqueous medium on a water soluble assimilable carbon containing substrate with at least part of the cultivation being conducted under conditions such that the micro-organism accumulates at least 10% by weight of polyester, characterised in that, at least during part of the period when polyester is being accumulated, the substrate comprises an organic acid, or derivative thereof, that is metabolisable by said micro-organism under said polyester accumulating conditions to a polyester other than one composed solely of --O.CH(CH.sub.3).CH.sub.2.CO-- repeat units, the amount the combined carbon in said acid, or derivative thereof, constituting at least 2% by weight of the total combined carbon in the substrate present throughout said period.
Dependencies are inferred from the claim text.