Original document(5 pages)  中文版
    This chalk is produced by extruding aqueous mixture of chalk powder and semihydrated gypsum powder. After treatment with a special liquid, it becomes of suitable hardness and writes smoothly and clearly. It has a clean surface, will not stain writer's fingers, and does not give off much dust when writing. Its raw materials are abundant, nonpoisonous and of low cost. All scraps and fragments can be recovered and reused, and there is no problem of waste disposal.
Application Number
申请号		 86103372 Application Date
申请日		 1986.05.15
Title 名称 Recipe and manufacturing process for making writing chalk giving very little dust
Publication Number
公开号		 1003898 Publication Date
公开日		 1986.10.08
Approval Pub. Date Granted Pub. Date 1987.12.09
International Classification 分类号 B43K19/00,C09D13/00
Applicant(s) Name
申请人		 Beijing Polytechnic College
Address 地址
Inventor(s) Name 发明人
Attorney & Agent 代理人 QIN YUEZHEN
More information 更  多  信  息


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