19 10 may be regarded as a milestone in the history of synthetic rubber development. This year, according to an accidental experimental result, Matthews of Britain published the first patent for preparing synthetic rubber by treating isoprene with metallic sodium. Almost at the same time, Hoffman of Germany discovered that dimethyl butadiene can be used to make rubber after heating. At that time, dimethyl butadiene could be easily prepared from acetone by reduction and dehydration, so both the United States and Germany at that time shifted the research focus of synthetic rubber raw materials from isoprene to here.
19 14 During the outbreak of World War I, Germany was forced to look for natural rubber substitutes as strategic materials because Britain blocked the supply of natural rubber, so "methyl rubber" with dimethyl butadiene as raw material came into being. At that time, it mainly produced two grades: H type for hard rubber products and W type for soft rubber products. The monomer was placed in a container with air at 30℃ for 6 ~ 10 weeks to obtain H-type product. This hard product needs long-term plasticization to be made into elastic material. W-shaped products were prepared by polymerization at 70℃ for 3 ~ 6 months in a double-layer pressure vessel without catalyst, and needed to be plasticized and softened before use, which shows how difficult it was to produce some synthetic rubber at that time. In this way, Germany produced more than 2000 tons of synthetic rubber during the First World War. Compared with natural rubber, the performance of methyl rubber is much worse, but it is the earliest synthetic rubber mass produced by human beings.
The earliest production process of methyl rubber is as follows: