Controlled-release compositions for acids
US4923753A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 26, 1987 |
| Grant date | May 8, 1990 |
| Priority date | — |
| Expiry date | Mar 26, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2989
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A controlled release composition for use with liquid acids, and a method of preparation is disclosed. The composition comprises (1) a porous matrix comprising and substantially inert to an absorbed acid; (2) a midlayer surrounding the matrix, this midlayer consisting essentially of a salt of the absorbed acid; and (3) a membrane surrounding the matrix, the membrane being exterior of the midlayer, the membrane further being substantially inert to the midlayer and permeable to a selected environment, the thickness and permeability of the membrane comprising means for controlling diffusion of the environment therethrough. The midlayer can be applied as a coating to the acid-bearing matrix, or it can be evolved by exposing the acid-bearing matrix to a base such as ammonia gas or a solid metal oxide for a time sufficient to allow reaction of a proportion of the acid at or near the surface of the matrix with the base to form a layer of the corresponding salt.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.