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
1996-08-16
1998-06-09
Schofer, Joseph L.
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...
525412, 525415, C08K 509
Patent
active
057635188
DESCRIPTION:
BRIEF SUMMARY
This invention relates to fully biodegradable and photodegradable polymer blends and to methods of making the same.
More specifically, the present invention relates to blends of polyisoprene and polycaprolactone which have thermoplastic properties, and which are biodegradable in soil and sea water environments, and photodegradable.
As a result of concerns about the environment and disposal of waste materials, a great deal of effort has been directed towards the development of biodegradable plastic materials. The main emphasis of such effort has been placed on the mechanisms of photodegradation and biodegradation. Photodegradation is the decomposition of photosensitive materials initiated by the ultraviolet component of natural light, and biodegradation results from the action of microorganisms such as bacteria, fungi or algae.
Photodegradablity is an inherent property of some polymers and in certain cases it can be enhanced by the use of photosensitizing additives. Photodegradable plastics have found use in applications such as agricultural mulch film, trash bags, and retail shopping bags.
Several different types of plastics have been produced which are fully or partially biodegradable. Some effort has been made to modify non-biodegradable polymers with starch in concentrations of 2-15%. However some controversy remains as to whether such materials are completely biodegradable. Some newer materials which use starch as part of the polymer matrix at levels of 60-100% are reported to be completely biodegradable. Certain polyester polymers have been shown to be biodegradable. These include aliphatic esters such as polyhydroxybutyrate-valerate (PHBV) and polycaprolactone.
Polycaprolactone blends are known which contain a variety of thermoplastic resins including polyethylene, polystyrene and nylon and are degradable in soil or sea water. However, because of the presence of non-biodegradable resin components, such blends are not completely biodegradable. In addition, the blends do not possess accelerated photodegradation abilities as measured against the properties of widely used commercial plastics.
The polyisoprene-polycaprolactone blend disclosed by Canadian Patent No. 1,111,179 which issued to Eric G. Kent on Oct. 20, 1981 is described as having thermoplastic properties. The patented invention is used for molding components of orthopedic devices specifically because of the mechanical and thermal properties of the material. Canadian Patent No. 1,080,875, which issued to Eric G. Kent on Jul. 1, 1980 also describes a blend containing polyisoprene and polycaprolactone. Because of its mechanical properties, the blend is used in the manufacture of sporting goods, specifically golf ball covers. Japanese Patent No. JP 89293048 describes a multi-component biodegradable coating consisting of polycaprolactone, olefinic polymers, wax, petroleum resin and fats and their derivatives including metal salts. The possibility of introducing a natural resin (polyisoprene) into such a coating is mentioned. Moreover, one of the resins mentioned is natural rubber. Fertilizer grains are coated by such a coating, which is degraded by microorganisms in the soil.
None of the above mentioned patents suggests using a composition for manufacturing a product using known plastic working methods such as injection molding, extrusion, blow molding or similar techniques which have significant importance in applications for biodegradable and photodegradable plastics. Moreover, none of the patents suggests a composition which is photodegradable or biodegradable in sea water. Only the Japanese patent mentions a composition with the ability to biodegrade in soil.
Known biodegradable polymers have suffered slow acceptance due to limitations in processing and high costs relative to conventional, non-degradable polymers.
An object of the present invention is to provide a plastic material which can be made economically is completely biodegradable and photodegradable, and which has thermoplastic properties comprising a blend of polyisoprene and polycap
REFERENCES:
patent: 3931090 (1976-01-01), Amatangelo
patent: 4032479 (1977-06-01), Bunnomori et al.
patent: 5352498 (1994-10-01), Kansupada
patent: 5610214 (1997-03-01), Olson
Fookes David
Foster Terry
Gnatowski Marek
Koutsandreas Andy
Minister of National Defence National Defence Headquarters
Sarofim N.
Schofer Joseph L.
Seaby George A.
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