Rubber: Production and processing

Rubber: The key to our mobility

In order to ensure our mobility around 29 million tons of rubber are currently processed each year. Of this amount, around 15 million tons are synthetic and 14 million tons are natural rubber.

Because the demands of rubber products are steadily increasing, but it is not possible to synthetically produce rubber in the required quality, the share of natural rubber is growing constantly because no other product is as tough and at the same time as elastic as this natural raw material. In the 1970s, total consumption of natural rubber was only 29 percent; today that share is over 48 percent.

Just equipping one car with tires requires the annual natural rubber harvest of up to five rubber trees. In order to meet the world’s current demand for natural rubber, natural rubber has to be harvested every day from 2.6 billion trees situated on an area as large as Holland.

According to estimates from the International Monetary Fund (IMF), the demand for natural rubber will increase to over 16 million tons per year come 2024. In order to satisfy this demand, new rubber plantations are needed with a total area of up to two million hectares and over 800 million rubber trees.

The economic significance of the rubber tree (Hevea brasiliensis) is thus enormous. It is among the most important suppliers of renewable raw materials.

Natural rubber, which is harvested from the latex of the rubber tree, is the main material in the production of rubber. Moreover, the rubber tree yields wood of exceptional quality, which can be made into furniture and many other wood products.

In order to meet the constantly growing demand, the rubber tree is now grown mostly on plantations. Optimized growing times of around 15 years ensure that in addition to the daily production of latex there are high amounts of wood on a regular basis.

Economically successful rubber plantations require a subtropical to tropical climate, which is only found in the so-called rubber belt between 15º north latitude and 15º south latitude. The most important growing regions for the rubber tree today are Southeast Asia, Latin America, China, and West Africa. The rubber tree originates from the rainforests of South America and is a type of hardwood.

The tremendous demand for natural rubber has prompted decades of agricultural and forestry research into the rubber tree with a view to enhancing both the latex and the wood yields. In Southeast Asia, where more than 70 percent of the world’s latex originates, rubber tree varieties have been developed through cultivating, crossing, and cloning, and are characterized by fast growth, above-average latex production, high amounts of wood, durability, and resilience. Newer plantations, which are cultivated with these types of rubber trees, are already producing up to 4,000 kilograms of latex per hectare after five or six years.

Latex is the fluid the rubber tree secretes if it is tapped professionally. The latex fluid flows in the sapwood area of the stem right below the tree bark in capillaries, where water and dissolved nutrients also circulate.

If ammonia is not added to the secreted latex within roughly two hours, the latex coagulates in the collecting container into a lump of rubber, also called cup lump. This coagulation cannot be reversed. For numerous applications cup lump rubber is the perfect raw material, such as for manufacturing TSR standard products which are in high demand in the tire industry. For subsequent processing to other products, such as hygienic gloves used in healthcare industry or in gastronomy, the secreted latex is kept fluid by adding ammonia and later sold in the liquid form. The reason for this is that rubber gloves, condoms, and other similar products are manufactured in the so-called dipping method. Here, dipping molds are dipped into a liquid latex mixture for a period of time.