Activators

Activators act as catalysts in the vulcanisation process by improving the efficiency of the vulcanisation accelerators. These additives support the chemical process in which sulphur molecules are incorporated into the polymer network of the rubber to achieve the desired elasticity and strength.

Chemical activators

The most common activators are zinc oxide (ZnO) and stearic acid. These two substances are often used together to increase the speed and effectiveness of vulcanisation. Zinc oxide reacts with the accelerators and sulphur, which speeds up the formation of sulphur bridges in the polymer chains.

Physical effects of activators

Activators allow the vulcanisation process to be carried out at lower temperatures and over shorter periods. This is particularly advantageous for saving energy and increasing efficiency in industrial production. Activators also ensure an even distribution of the vulcanisation components within the rubber compound.

Activators are used in a wide range of rubber products to improve processing and ensure the desired properties of the end product. Here are some examples:

Tyre production

In the tyre industry, activators such as zinc oxide are used to ensure uniform vulcanisation. Optimising the formation of sulphur bridges increases the durability and abrasion resistance of tyres, which is crucial for the safety and service life of vehicle tyres.

Manufacture of seals and hoses

Rubber seals and hoses used in the automotive and mechanical engineering industries benefit from the improved vulcanisation provided by activators. Activators ensure that rubber seals remain flexible while still withstanding the high mechanical demands they are exposed to.

Electronics and cable industry

In the manufacture of rubber cables and electrical insulators, activators ensure uniform crosslinking of the elastomer, making the products heat-resistant and electrically insulating. This is crucial for safety in electrical and electronic applications.

The use of activators offers industry numerous advantages that improve both production and the quality of the end products:

• More efficient vulcanisation: activators speed up the vulcanisation process and reduce energy consumption by improving the reactivity of the vulcanisation systems.

• Improved product quality: more uniform vulcanisation makes rubber products more resistant, more elastic and longer-lasting.

• Cost reduction: faster and more efficient processes lower production costs and reduce scrap in manufacturing.

Zinc oxide is one of the most commonly used activators. It reacts with vulcanisation accelerators and sulphur to promote the vulcanisation process and ensure that vulcanisation proceeds efficiently and uniformly.

2. Why is stearic acid often used together with zinc oxide?

Stearic acid acts as a co-activator that increases the effectiveness of zinc oxide. It improves the solubility of zinc oxide in the rubber compound and so facilitates the chemical reactions that lead to vulcanisation.

3. Can the amount of activators influence the properties of the end product?

Yes, the correct dosage of activators is crucial. Too much activator can accelerate vulcanisation excessively and lead to uneven results, while too little slows vulcanisation down, and the desired material properties may not be achieved.

4. Are activators environmentally friendly?

The environmental compatibility of activators depends on the materials used. Zinc oxide is considered relatively environmentally friendly, but some other activators may be subject to environmental regulations. Research into more environmentally friendly alternatives is increasing in order to improve the sustainability of production.

Activators are crucial for the efficiency and quality of vulcanisation in the rubber industry. Their targeted use speeds up the vulcanisation process, improves material properties and lowers production costs. In applications ranging from tyres to seals and hoses, activators play a central role in ensuring the performance and durability of the end products.