| 摘要 |
FIELD: used for writing lines (texts, drawings or the like) and for marking out fabrics, metal, wood and other materials. SUBSTANCE: composition comprises the following components (wt%): 19.4-42.9; gypsum binder; 14.3-45.2 filler; and the water balance. No need to use complex and expensive equipment or additive. Besides, expensive gypsum binder is replaced by cheaper natural materials such as tripolite, diatomite or chalk. EFFECT: improved properties of writing chalks, simpler technology of manufacture and lower manufacturing cost. |
