Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones

Definitions

• This invention relates to a method of hot shaping polymers and in particular to such a method characterized by the nature ofthe polymer feed to the method.
• Hot shaping methods include extrusion of melt, melt coating, compression moulding, injection moulding, extrusion blow moulding and casting.
• a common feature of these methods is that solid polymer powder is fully or locally melted and caused to flow into a shaping space.
• the particle size ofthe polymer powder starting material is carefully controlled to avoid dusting and to ensure uniform flow into the shaping machine.
• For such particle size control it is usual to subject polymer raw material to pre-extrusion to strands about 3 mm thick and to chop the strands into short lengths about 3 mm long. This has the undesirable effect when the polymer is a polyhydroxyalkanoate (PHA) of causing a significant loss in molecular weight.
• PHA polyhydroxyalkanoate
• the PHA polymer raw material as available from microbiological production is of such a particle size that pre-extrusion is essential.
• Co-pending application WO 94/02622 describes a process of agglomerating PHA particles in suspension in water optionally containing at least partly chemically degraded non-PHA microbial cell material (NPCM) by maintaining the suspension at a relatively high temperature, for example over 100°C but at least 30°C below the peak melting point of the PHA (as determined by differential scanning calorimetry).
• NPCM non-PHA microbial cell material
• a polymer hot shaping method is characterised by using as feed to the shaping machine a polymer powder made by agglomerating fine polymer particles in presence of hot water. 2 -
• the invention is more particularly a process of making a shaped object of microbiologically produced PHA by the steps:
• the PHA is especially capable of a relatively high level of crystallinity, for example over
• m in the range 1-13 and n is 2m or (except when m is one) 2m-2.
• C m H. contains 2-5 carbon atoms in the polymer chain and the remainder (if any) in a side chain.
• m is 3 or 4
• the molecular weight of the polymer is for example over 50000, especially over 100000, up to e.g. 1 x IO 6 .
• the microorganism may lay down PHA during normal growth or may be caused to do so by cultivation in the absence of one or more nutrients necessary for cell multiplication.
• the microorganism may be wild or mutated or may have had the necessary genetic material introduced into it. Alternatively the necessary genetic material may be harboured by a eukariote, to effect the microbiological process.
• Step (b) typically comprises subjecting the biomass, possibly after concentration, to one or more mechanical steps such as homogenisation, thermal steps such as heat shock at 100- 200°C, enzymatic steps such as by proteolytic enzyme or hydrolase such as lysozyme, surfactant digestion, or oxidation such as by peroxide or hypochlorite. Very suitably it is subjected to peroxide, optionally after at least one of the mechanical, thermal or enzymatic steps.
• the peroxide treatment is preferably by hydrogen peroxide in presence ofa metal sequestering agent.
• One or more surfactants may be present, as an NPCM solubiliser or dispersion stabiliser or for other purposes.
• An alternative process for producing the suspension includes extracting the PHA by means of a volatile water-insoluble solvent such as chloroform and emulsifying the resulting solution in water.
• a further alternative includes melting the PHA out from the cells, possibly in presence of a water-soluble solvent, then shearing the resulting melt or solution with water.
• the temperature in step (c) is by 30-80°C, preferably 40-70°C lower than the melting point ofthe PHA as measured by DSC. Typically the temperature is over 100°C and agglomeration is carried out under superatmospheric pressure. It will be appreciated that the temperature is stated in terms of the DSC melting point of the PHA because the PHA particles at the time of agglomeration are in transition between the amo ⁇ hous state and the crystalline state, so that their melting point cannot be known.
• step (c) typically increases this to at least 50, preferably 100-5000, for example 200-500, ⁇ m.
• Their porosity is then typically at least 0.6, especially 0.7 to 0.8, by volume.
• polymer processing additives such as nucleant, pigment, filler, plasticiser or additional polymer can be introduced in this step, before, during or after agglomeration.
• the particles are porous enough to absorb plasticiser to the extent required, for example 5-20 phr by weight.
• the agglomerates may be separated from the aqueous phase of the suspension by for example decantation, filtration or centrifugation.
• decantation filtration or centrifugation.
• step (e) hot pre-compounding is replaced by simple cold mixing, followed if necessary by drying if a volatile liquid such as water has been used to introduce a component of the material to be shaped. If shaping is to be by screw extrusion, dry mixing may be sufficiently effected in passage through the extruder screw.
• the gap between the extruder die lips was set to 0.4 mm; the air gap between these lips and the nip was set to about 10cm.
• the paper line speed was 20-40 m min. Downstream of the chill-roll, the coated web was heated to approximately 80°C with an infra red heater to crystallise the PHBV. The coating was satisfactory in its appearance and ran smoothly through to the wind-up. The coated paper could be unwound without any difficulties.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Polyesters Or Polycarbonates (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=10785981

Family Applications (1)

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Family Cites Families (4)

• 1995
  • 1995-12-22 GB GBGB9526388.5A patent/GB9526388D0/en active Pending
• 1996
  • 1996-12-18 AU AU13466/97A patent/AU1346697A/en not_active Abandoned
  • 1996-12-18 JP JP09523848A patent/JP2000502399A/ja active Pending
  • 1996-12-18 EP EP96944999A patent/EP0868471A1/de not_active Withdrawn
  • 1996-12-18 WO PCT/US1996/020545 patent/WO1997023549A1/en not_active Application Discontinuation
• 1998
  • 1998-06-22 MX MX9805097A patent/MX9805097A/es not_active Application Discontinuation

Non-Patent Citations (1)

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