Humidity indicators

Abstract

The invention provides a humidity indicator which does not contain cobalt chloride. The humidity indicator comprises a vector. A solvent for the vector is water, and the main compositions by mass percentage of the vector in the solution are 10 to 30 percent of bluestone or blue vitriol and 0.5 to 12 percent of bromine salt; and the solution is used for discoloration. The indicator has wide indicating range (can indicate 5 to 80 percent of the ambient humidity) and high sensitivity. The indicator is brown before absorbing the humidity and is converted into cyan after absorbing the humidity, so that the indicator has obvious discoloration effect and high sensitivity.

Description

technical field [0001] The invention relates to an indicator for displaying humidity, in particular to a cobalt-free humidity indicator. Background technique [0002] Humidity indicator materials currently on the market, such as humidity indicator cards, color-changing silica gel, etc., mostly use cobalt chloride as the indicator. Cobalt chloride was identified as a second-class carcinogen by the European Union in 1998 in the revision XXV of European Directive 67 / 548, so the production of humidity indicator materials containing cobalt chloride has been banned in Europe and the United States and phased out. In order to find one or more components that can functionally replace cobalt chloride, researchers have been making unremitting efforts. Among them, the CN1365447A patent application published on August 21, 2002 discloses a "humidity indicator of desiccant absorption capacity". This technology does not use cobalt chloride, but uses copper chloride as the active ingredien...

AI Technical Summary

Problems solved by technology

However, copper chloride is easily combined with chloride ions to form [CuCl 4 ] 2+ , while [CuCl 4 ] 2+ The corresponding solvent is yellow. When the indicator absorbs moisture, it will form a color configuration with the blue medium formed by the indicator, which will cause the indicator to appear green after moisture absorption.