Composition for non-toxic, non-hazardous, and environmentally friendly humidity-indicating agent and its application

摘要

Cobalt chloride, copper chloride, and zinc chloride have been used as a humidity-indicating medium. European Union classified cobalt chloride as a category 2 carcinogen while repeated exposure to copper chloride can lead to copper poisoning. Zinc chloride is also known to be very harmful to the environment. These materials are very toxic to aquatic organisms and may cause long-term adverse effects in the aquatic environment. The present invention relates to composition for non-toxic, non-hazardous, and environmentally friendly humidity-indicating agent and its application to humidity indicator, specifically humidity indicator card and humidity-indicating desiccant. The present invention discloses a humidity-indicating agent comprising; pH indicator dye, colour-enhancing additive, and natural hygroscopic salt such as magnesium chloride and sodium chloride. All of the ingredients are carefully selected from non-toxic, non-hazardous, and environmentally friendly materials. The humidity-indicating agent changes colour reversibly as a function of the relative humidity.