IMPAFLOW – Zinc peroxide paste for elastomer cross-linking

The declining availability of zinc peroxide pastes is a challenge for many elastomer manufacturers. But a new ready-to-use paste made from zinc peroxide with plasticizers offers a stable, homogeneous solution for efficient cross-linking. It improves work safety, facilitates processing, and allows for precise, time-controlled vulcanization.

Manufacturing elastomers is a sensitive process: the correct mixture of individual components and control of the reaction must be coordinated perfectly to achieve the best possible results. 

Accordingly, for some time now, our customers in elastomer manufacturing have been using zinc peroxide pastes for producing their special products. Yet, the availability of zinc peroxide pastes on the market has been steadily declining in recent years, as fewer and fewer manufacturers offer this special product. 

In order to improve supply reliability, we have decided to take up the production of these special pastes for our customers. 

What is IMPAFLOW?

It is a ready-to-use paste based on zinc peroxide and plasticizers, specially developed for the efficient cross-linking of elastomers. The zinc peroxide we use is a mixture of fine-grained zinc oxide with a peroxide shell. By combining it with plasticizers, we obtain a stable, homogeneous mixture.

Customization – options for individual adaptations

Our zinc peroxide paste currently comes with the plasticizers diisononyl phthalate (DINP) and 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH), under the names IMPAFLOW DINP and IMPAFLOW DINCH. 

On request, we can also supply pastes containing other plasticizers, for individual custom solutions. 

Improved work safety and optimized process control

The paste form reduces the amount of dust produced during later processing, thereby improving occupational safety. Because incorporating zinc oxides into rubber compounds is sometimes difficult, especially for variants with a large specific surface area, the pre-dispersed paste form helps to achieve homogeneous incorporation and precise dosing in rubber compounds. 

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Delayed activation of cross-linking

IMPAFLOW is developed for producing rubber articles with high temperature resistance and optimized dynamic properties. Our paste can also be used as a time-controlled activator for cross-linking. The targeted and controlled decomposition of the peroxide shell at high temperatures enables controlled release of zinc oxide as an activator or accelerator of cross-linking. 

This delayed release in turn allows for better control in the vulcanization process. This improves overall process control in the manufacture of elastomers significantly, especially those with long processing times and complex geometries.

Targeted release and mechanical advantages of zinc oxide

Given the way that zinc oxide is released during production and cross-linking, you get the typical advantages of zinc oxide along with stable and easily controllable process management. 

In addition to its action as a cross-linking activator, the zinc oxide released can also modify mechanical properties. 

Adding zinc oxide to rubber compounds typically improves the following parameters:  

• Tensile strength
• Heat resistance
• Wear resistance
• Elasticity
• Aging resistance (UV protection)

Role of zinc oxide in peroxide cross-linking 

In the process of peroxide cross-linking, zinc oxide acts as an acid acceptor and can increase heat resistance. Acidic components introduced by fillers and other materials, or the often acidic by-products of decomposing peroxides (e.g. carboxylic acids or phenols), can inhibit the cross-linking reaction or degrade the polymer. ZnO neutralizes these acids by forming zinc salts:

2 R-COOH+ZnO →(R-COO)_2 Zn+H_2 O

Zinc peroxide pastes are therefore an ideal addition to our portfolio for elastomer production.