Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1993-02-11
1994-01-25
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
525378, C08K 328, C08C 1922
Patent
active
052816494
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a hydroxyalkanoate polymer composition and to a process for the production thereof, and in particular to a 3-hydroxybutyrate polymer composition and to a process for the production thereof.
Homopolymer of 3-hydroxybutyrate, known as poly(3-hydroxybutyrate), or PHB, is a thermoplastic polyester consisting of monomer units of the formula: example of the genera Alcaligenes, Athiorhodium, Azotobacter, Bacillus, Nocardia, Pseudomonas, Rhizobium, and Spirillium, as an energy reserve material.
PHB is conveniently prepared by cultivating the microorganism in an aqueous medium on a suitable assimilable substrate, such as a carbohydrate or methanol, as an energy and carbon source. Examples of suitable processes are described in EP-A-15669 and EP-A-46344.
Other polymers containing monomer units of 3-hydroxybutyrate in combination with other monomer units, such as 3-hydroxyvalerate units, can also be produced microbiologically. Such combinations of dissimilar monomer units are termed copolymers. Thus a microbiologically produced copolymer containing 3-hydroxybutyrate and 3-hydroxyvalerate residues is described by Wallen et al in "Environmental Science and Technology", 8, (1974), 576-9. Also, as described in EP-A-52459 and EP-A-69497, various copolymers can be produced by cultivating the microorganism on certain substrates, such as propionic acid which gives rise to 3-hydroxyvalerate units in the copolymer.
Copolymers can also be made containing monomer units of other hydroxycarboxylic acids and/or units derived from diols, e.g. ethylene glycol, and/or dicarboxylic acids, e.g. isophthalic acid, by ester interchange occurring when the microbiologically produced polymer or copolymer is melted with such a hydroxycarboxylic acid, lactone thereof, e.g. pivalolactone, diol, dicarboxylic acid and/or polyester produced therefrom.
In the following description therefore, by the term HB polymer we mean not only PHB, but also copolymers as described above, provided that 3-hydroxybutyrate monomer units form at least part of the polymer chain.
While cells containing the HB polymer can be used as such as a moulding material, for example as described in U.S. Pat. No. 3,107,172, it is generally desirable to separate the HB polymer from the remainder of the cell material.
Methods that have been proposed to effect this separation include breakage of the cells by methods such as treatment with acetone, followed by extraction of the HB polymer from the broken cells by treatment with a solvent in which the HB polymer is soluble. Examples of such processes are described in U.S. Pat. No. 3,036,959 and U.S. Pat. No. 3,044,942 in which the solvents employed are pyridine or mixtures of methylene chloride and ethanol. Other extraction solvents for the HB polymer in the form in which it is produced in the cells include cyclic carbonates such as 1,2-propylene carbonate (see U.S. Pat. No. 4,101,533); chloroform (see U.S. Pat. No. 3,275,610); and 1,2-dichloroethane (as disclosed in EP-A-15123).
U.S. Pat. No. 3,275,610 discloses other methods of cell breakage, viz. ultrasonic vibration, grinding, French pressing, freezing/thawing cycles and lysozyme treatment, while as described in EP-A-15123, spray or flash drying of the suspension of cells as produced by culturing the microorganism can also cause sufficient cell breakage to enable the HB polymer to be extracted from the cells.
HB polymer can be made into shaped objects using known shaping techniques under conditions such that crystallisation of the polymers usually takes place. Such shaping techniques include processes in which HB polymer is thermally treated, e.g. injection moulding.
A particularly important factor in HB polymer processing is the crystallisation rate. The rate of crystallisation of HB polymer is generally slow, and is controlled to a major extend by the growth rate of individual crystals, and the nucleation density, both of which tend to be low. In copolymers containing hydroxyvalerate monomer units (HV copolymers), the crystallisation rate is dependent up
REFERENCES:
patent: 3471455 (1969-10-01), Binsbergen
patent: 4900299 (1990-02-01), Webb
Barham Peter J.
Organ Sally J.
Webb Andrew
Imperial Chemical Industries plc
Michl Paul R.
Szekely Peter
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