Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1996-04-29
1998-05-19
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
424444, 424 7806, 524270, C08G28304
Patent
active
057537828
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a polyester composition and in particular to such a composition containing biodegradable polyester and plasticiser.
Biodegradable polyesters for example the microbiologically produced polyhydroxyalkanoates can be adapted by the use of plasticiser compounds for applications where improved impact strength, improved elongation to break and improved ductility are important. Since such compounds should preferably also be biodegradable, many of the plasticisers used in synthetic polymer processing are not suitable for biodegradable polymers. Most commonly the glyceryl ester triacetin (glycerol triacetate) is used, but it is more volatile than is ideal during melt processing or storage at high ambient temperatures. Recently, a new plasticisier called Estaflex* (acetyl tri-n-butyl citrate) has been introduced for polyhydroxyalkanoates which is an improvement over triacetin, however, alternatives to these compounds are continually sought for further improvements in physical properties of the polymer, improvements in the biodegradablility and resistance to migration in the polymer, improvements in flexibility, mobility and permanence, and economic benefits. In looking for new plasticisers the applicants have unexpectedly found that a number of plasticisers or materials used in conventional plasticised systems are useful plasticisers of biodegradable polyesters.
Thus, according to the present invention there is provided a polyester composition comprising a biodegradable polyester and a plasticising quantity of at least one plasticiser selected from the group: high-boiling esters of polybasic acids; phosphoric acid derivatives; phosphorous acid derivatives; phosphonic acid derivatives; substituted fatty acids; high-boiling glycols, polyglycols, polyoxyalkylenes and glycerol each optionally substituted and optionally terminally esterified; pentaerythritols and derivatives; sulphonic acid derivatives; epoxy derivatives; chlorinated paraffins; polymeric esters; Wolflex-But*; provided that citrates does not include doubly esterified hydroxycarboxylic acids having at least 3 ester groups in its molecule and further provided that glycerols does not include glycerol triacetate and glycerol diacetate.
In the description, examples and claims herein a * indicates a tradename or registered trademark.
The majority of plasticisers used in this invention are known in the art as plasticisers of other materials. A plasticiser is a material which when added to a polymer composition makes an improvement in the ductility of the polymer. It is generally the case with most plasticised polymer systems that the extent of the plasticising effect is in direct correlation with the glass transition temperature (T.sub.g) of the plasticised material, i.e. the lower the T.sub.g the greater the plasticising effect. It has now been found that in the biodegradable polyesters of the present invention, the glass transition temperature is not a predictor of the extent of beneficial effect of the plasticiser of the polymer, and surprisingly the plasticisers of the present invention are unexpectedly useful with the biodegradable polyesters of the present invention.
The biodegradable polyester may be for example, polylactic acid, polycaprolactone, polyethylene succinate, polypropylene succinate, polybutylene succinate, polyhydroxyalkanoate (PHA), for example polyhydroxybutyrate (PHB) or copolymers of hydroxybutyrate with hydroxyvalerate, i.e. polyhydroxybutyrate-co-hydroxyvalerate, (PHBV). It may be for example a poly-2-hydroxyalkanoate such as a polyglycollic acid or it may be a synthetic polypropiolactone, polybutyrolactone, polyvalerolactone, or a caprolactone copolymer.
Examples of suitable synthetic polyesters are especially polycaprolactone, polylactides, and polyesters containing combinations of dicarboxylic acids or derivatives thereof and diols. Dicarboxylic acids being selected from the group consisting of malonic, succinic, glutaric, adipic, pimelic, azelaic, sebacic, fumaric, 2,2-dimethylglutaric, suberic, 1,3-cyclopen
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Baptist, et al: "Poly--Hydroxybutyric Acid-A Naturally Occurring Thermoplastic Material", SPE Transactions, Oct. 1964, pp. 245-250.
Ceccorulli, et al: "Plasticization of Bacterial Poly(3-hydroxybutyrate), Macromolecules" 1992, 25, 3304-3306.
Chemical Abstract: "TP-90B Plasticizer", Morton International, Apr. 1991.
Chemical Abstract: "TP-759 Plasticizer", Morton International, Mar. 1991.
Hammond Timothy
Liggat John Jamieson
Montador James Henry
Webb Andew
Mosley Terressa
Zeneca Limited
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