Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1997-11-06
1999-07-20
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528176, C08G 6300
Patent
active
059257261
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process according to the preamble of claim 1 for preparing a thermoplastic, biodegradable polyester.
According to the process a lower molecular weight polyester-prepolymer is first formed from hydroxy acid monomers, and then the prepolymer is copolymerized with a monomer which reacts with its end groups in order to form a polymer having a high molecular weight.
The invention also relates to a copolyester according to the preamble of claim 21 and to a polyester according to the preamble of claim 39, which can be used as a precursor (prepolymer) for the preparation of the copolymer.
There are a number of applications for biodegradable polymers, such as expendable packings, paper coatings and compostable waste packages, wherein compostability significantly increases the competitiveness of the materials. The use of traditional biodegradable polymers in packages and in other bulk applications are, however, limited by the very high price of the polymers.
One specific group of biodegradable plastics comprises aliphatic polyesters, which are biologically degradable due to the presence of hydrolysable ester bonds. The polyesters are generally prepared from hydroxy acids or diacids and diols. Before the mechanical properties of the polymer are sufficiently good, its molar mass must be rather high, and the most common way of achieving a high molar mass is to manufacture the polyester by the ring-opening lactone mechanism.
Lactic acid is a potential raw material for biodegradable bulk polymers. The preparation of polylactide (PLA) by the ring-opening mechanism from lactic acid via an intermediate lactide stage produces polymers having high molar masses, but it requires several intermediate stages and a very pure feedstock, and the total yield of polymer from lactic acid is very low.
Structurally PLA is a straight-chained polyester, and no long-chain branching will take place. The rheological properties of straight-chained polyester melts impair their use in most preparation processes employing extrusion technology, such as blow moulding, film blowing and paper coating. These processing methods which require great strength and elasticity of the melt are, however, the most important manufacturing processes of the packaging industry.
Typically, straight condensation polymerization of aliphatic diols and diacids or hydroxy acids give rise to a number average molar mass of about 10,000 g/mol, at the most, and often, technically and economically, the sensible molar mass is about 2,000-5,000 g/mol.
A method is known in the art that makes it possible to prepare a high molar mass polyurethane suitable for melt-processing from lactic acid monomers. This method disclosed in FI Patent Application No. 924699 comprises preparing the polymer in two stages by first polymerizing the lactic acid to form an oligomer of lower molar mass, and then copolymerizing the oligomer with isocyanate to form a high molar mass polyurethane.
It is an object of the present invention to provide an alternative way of preparing melt-processible, hydroxy acid monomer based polymers with high molar masses, which are easily processed into desired shape. It is another object of the invention to provide a biodegradable polymer, wherein all or practically all hydrolysable bonds are comprised of ester bonds and which does not essentially contain any nitrogenous functions.
The invention is based on the idea of subjecting the lactic acid or another hydroxy acid or diacid and diol to a straight polycondensation reaction and then to raise the molar mass of the propolymer thus obtained by chemically coupling the chain ends of the polymers with the aid of diepoxy compounds. As a result, a thermoplastic biodegradable copolyester is obtained having a clearly higher molar mass than the prepolymer.
The process according to the invention substantially comprises two stages, the first stage consisting of preparing a prepolymer by polymerization of hydroxy acids to prepare in within a reasonable time span a carboxylic acid -terminated linea
REFERENCES:
patent: 3739041 (1973-06-01), Schmid et al.
patent: 5380813 (1995-01-01), Seppala et al.
patent: 5470944 (1995-11-01), Bonsignore
English Language Abstract of JP-A-6032357.
English Language Abstract of JP-A-5342903.
English Language Abstract of JP-A-06239984.
Journal of Polymer Science: Part A: Polymer Chemistry, vol. 31, 1993, Storey et al., New Epoxy-Terminated Oligoesters: Precursors to Totally Biodegradable Networks, pp. 1825-1838.
Hakola Jyrki
Harkonen Mika
Hiltunen Kari
Selin Johan-Fredrik
Seppala Jukka
Mosley Terressa
Neste Oy
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