At present, the majority of schools used in the blackboard writing tools are traditional blackboard, chalk, its use in the process of dust flying, pollution teaching environment. Because of the carcinogenic substances in the dust, China's Disease prevention Center data show that every full-time teacher in the annual intake of chalk dust in the body of about 250~260 grams, the incidence of cancer accounted for 20% of the total incidence of the country, 8 times times the general population. The students are also suffering. The traditional chalk also has the writing laborious, wipes countless, causes the precision teaching instrument service life to shorten and so on many shortcomings.
The market has a common blackboard and chalk Substitutes: Whiteboard and whiteboard pens. But because of the high price, not in line with the long-term formation of teachers writing habits and reflective more serious problems, has not been universal.
Whiteboard pen is flawed, but it can give us some inspiration: the development of liquid chalk.
According to a variety of domestic and foreign information on the development of liquid chalk, we have tentatively determined the chemical composition of the ink: to edible alcohol as the base, with titanium dioxide as the primary color, by the surfactant, conjunctival agent, wetting agent, driers and colorants in a variety of proportions by dispersion, grinding fine.