METHOD FOR CONTROLLING EXPANSION PROPERTIES OF THERMALLY EXPANDABLE SULFURIC ACID-GRAPHITE PARTICLES AND USES OF SULFURIC ACID-GRAPHITE PARTICLES

摘要

PURPOSE: To provide a method capable of selectively and easily influencing the expansion properties of thermally expandable sulfuric acid-graphite particles, particularly regarding the expansion volume, the expansion rate and the average expansion coefficient. CONSTITUTION: In the method, sulfuric acid-graphite particles, produced by reacting graphite particles with sulfuric acid in the presence of an oxidizing agent, are washed with an aqueous washing liquid containing compounds affecting the expansion properties to a pH ranging from 2 to 8, measured in the washing liquid separated from the washed sulfuric acid-graphite particles, and then dried. The sulfuric acid-graphite particles are used as intumescing fire-retarding additives for producing fire-retarding compositions for sealing wall bushings and other openings in walls, floors and ceilings of buildings.