US 2004/0069033 A1 · Controlled release products and processes for the preparation thereof

Abstract

A controlled release product is provided having a suppressed initial release period and a predetermined longevity. The product includes a particulate water soluble core material and a semi-permeable coating layer applied on the core material for controlling the release rate of the core material. The semi-permeable coating layer is formulated in accordance with the following equation to provide a release rate wherein initial release of core material from the product is suppressed so that less than about 15 weight percent of core material is released from the product within a 24 hour period after application of the product and wherein longevity of release, at ambient temperature, between the time of application and the time at which at least about 75 weight percent of the core material is released from the product is 60 days or less: 1 WVTR = φ · δ π ⁢ ⁢ d 2 wherein: (i) WVTR is the water vapor transmission rate of the semi-permeable coating expressed in grams·μm/meters2·day; (ii)φ is the water diffusion rate (water flux) through the semi-permeable coating expressed in grams/day; (iii) δ is the thickness of the coating layer expressed in μm; and (iv) d is the average diameter of the particulate core material expressed in meters.

Claims27

Dependent claims

A controlled release coated product in particulate form which is structured to provide a suppressed initial release period and a predetermined longevity comprising:

(a) a particulate core material comprising a water soluble fertilizer composition;
and
(b) a single semi-permeable coating layer applied directly onto the surface of the particulate core material for controlling the release rate of the core material so that initial release of core material from the coated product is suppressed such that less than 15 weight percent of core material is released from the coated product within a 24 hour period after application of the coated product and longevity of release between the time of application and the time at which at least 75 weight percent of the core material is released from the coated product is 60 days or less at ambient temperature of about 21° C.;
and
(c) the single semi-permeable coating layer is formed from a composition selected from the group consisting of thermoplastic and thermosetting polymers and resins which form a uniform continuous polymeric film having a WVTR greater than 800 g.m/m2.day.

2 more elements

A process for producing a controlled release coated product in particulate form which is structured to provide a suppressed initial release period and a predetermined longevity comprising:

(a) providing a particulate core material comprising a water soluble fertilizer composition;
and
(b) applying a single semi-permeable coating layer directly onto the surface of the particulate core material to enable the core material to release from the coated product at a rate wherein initial release of core material from the coated product is suppressed so that less than 15 weight percent of core material is released from the coated product within a 24 hour period after application of the coated product and wherein longevity of release between the time of application and the time at which at least 75 weight percent of the core material is released from the coated product is 60 days or less at ambient temperature of about 21° C.;
the single semi-permeable coating layer being formed from a composition selected from the group consisting of thermoplastic and thermosetting polymers and resins which form a uniform continuous polymeric film having a WVTR greater than 800 g.μm/m2.day.

1 more element

Dependencies are inferred from the claim text.

Controlled release products and processes for the preparation thereof

Life of this patent

Controlled release products and processes for the preparation thereof

Life of this patent

Abstract

Claims27