United States Patent:  5,993,843

Assignee:  Research Association for Biotechnology of Agricultural (Tokyo, JP)

Filed:  June 27, 1997

Described are a biodegradable sustained-release preparation which comprises a mixture of 99 to 10 parts by weight of an aliphatic polyester and 1 to 90 parts by weight of a modifier for the regulation of sustained releasability of an active ingredient, and the active ingredient held by said mixture; a biodegradable pheromone dispenser, wherein an aliphatic polyester is used as a sustained release layer for a pheromone contained therein as a liquid phase, said aliphatic polyester having recurring units whose ratio (I/II) of (I) the number of the carbon atoms constituting the main chain and not relating to ester linkage to (II) the number of the carbon atoms constituting the ester linkage is 2 or larger; and a biodegradable pest controlling agent which is obtained by mixing and dispersing an active ingredient and a carrier for holding said active ingredient in a biodegradable aliphatic polyester or which comprises 2 to 60 wt. % of an active ingredient, 30 to 95 wt. % of a biodegradable aliphatic polyester and 2 to 50 wt. % of a carrier for holding the active ingredient.

SUMMARY OF THE INVENTION

An object of the first group of the present invention is to provide a biodegradable sustained-release preparation which can, during application, carry out sustained release of its active ingredient stably at a desired release rate for a long period of time and after application, is degraded by microorganisms even buried in the ground and does not remain in the soil.

The present inventor has found that release of an active ingredient can be controlled easily and all the problems described above can be overcome by mixing 99 to 10 parts by weight of an aliphatic polyester which has a small transmittance of the active ingredient and 1 to 90 parts by weight of a modifier for regulating the sustained release of the enclosed active ingredient, leading to the completion of the first group of the present invention.

In one aspect of the first group of the present invention, there is thus provided a biodegradable sustained-release preparation which comprises a mixture composed of 99 to 10 parts by weight of an aliphatic polyester and 1 to 90 parts by weight of a modifier for the regulation of the sustained releasing property of an active ingredient and the active ingredient held by said mixture.

An object of the second group of the present invention is to provide a reservoir type biodegradable pheromone dispenser which permits, during application, stable sustained release of a pheromone over a long period of time and after application, does not require collection work because of its biodegradability and therefore does not remain in the soil.

Polyester features that an ester linkage in its structure firmly combines molecular chains through a static bond so that it is difficult for pheromone molecules to diffuse the gap of the polymer segment, resulting in a small transmittance of the pheromone in the polyester. The present inventor has found that releasability of a pheromone can be controlled by widening the gap between ester linkages of the main chain structure of an aliphatic polyester and completed the invention of the second group.

In one aspect of the second group of the present invention, there is thus provided a biodegradable pheromone dispenser in which an aliphatic polyester is used as a sustained-release layer for a pheromone contained therein as a liquid phase, said aliphatic polyester having recurring units whose ratio (I/II) of (I) the number of the carbon atoms constituting the main chain and not relating to ester linkage to (II) the number of the carbon atoms constituting the ester linkage is 2 or larger.

An object of the third group of the present invention is to provide a biodegradable pest controlling agent which can be prepared easily, has excellent economical efficiency, permits easy regulation of a release rate or pot life, can satisfy the request for the reduction in the numbers installed or for aerial application, and because of its biodegradability, does not remain in the environment and therefore does not need collection work.

Thee present inventor has carried out an extensive investigation. As a result, it has been found that the above problems can be overcome thoroughly by mixing and dispersing in a biodegradable aliphatic polyester an active ingredient and a carrier,capable of retaining the ingredient at a high content, leading to the completion of the third group of the invention.

In one aspect of the third group of the present invention, there is thus provided a biodegradable pest controlling agent obtained by mixing and dispersing in a biodegradable aliphatic polyester an active ingredient and a carrier retaining the active ingredient therein.

In another aspect of the third group of the invention, there is also provided a biodegradable pest controlling agent which is a composition comprising 2 to 60 wt. % of an active ingredient, 30 to 95 wt. % of a biodegradable aliphatic polyester and 2 to 50 wt. % of a carrier retaining the active ingredient.

Claim 1 of 9 Claims

1. A biodegradable sustained-release preparation which comprises a mixture of 99 to 10 parts by weight of an aliphatic polyester and 1 to 90 parts by weight of a modifier for the regulation of sustained releasability of an active ingredient; and the active ingredient held by said mixture.

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