Method for preparing a controlled release composition

US4388352A · kind A · utility

Assignee

• The Board of Regents of the University of Washington · US

Inventors

• George G. Allan · Seattle, US
• Young-chul Ko · Seojong-myeon, KR

Key dates

• Filing date: Aug 3, 1981
• Grant date: Jun 14, 1983
• Expiry date: Aug 3, 2001

Classification

• Technology area (CPC D): Textiles; Paper
• CPC primary: D21C9/002
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

Controlled release compositions are made by a distillation method to include chemical impregnants (such as animal repellants, pesticides, herbicides, fungicides, plant growth stimulants, perfumes and deodorizers, fertilizers, and drugs) in biodegradable, microporous structures. Each microporous structure collapses upon drying but swells upon rewetting to allow the impregnant entrapped in it to diffuse from the structure. Never-dried wood pulp is a particularly desirable microporous structure because it has large pores initially, a large surface area initially, and demonstrated swelling capability. The method is particularly useful when the impregnant is insoluble in the fluid initially within the microporous structure and when the solvent for the impregnant is immiscible with that fluid.