Diversity at its Purest: HDK®

HDK® pyrogenic silica has been manufactured by WACKER since the 1970s. It is characterized by its exceptional purity and diversity. HDK® is ubiquitous in our daily lives: it is found in toothpaste, adhesives, printing inks and medicines.

The WACKER product portfolio contains a wide range of hydrophilic and hydrophilic HDK® grades and HDK® dispersions for all kinds of applications. Application areas include composites, printing inks, paints and coatings, adhesives, as well as the pharmaceuticals, foodstuffs and cosmetics industries. Thanks to its properties, HDK® has a positive effect on storage, drying and application behavior: it improves the scattering behavior of powders and influences the rheology and thixotropy of liquid substances. It also gives structure to external thermal insulation composite systems.

Fire and Flames: How HDK® is Made

Hydrophilic HDK® is manufactured by the hydrolysis of volatile chlorosilanes in an oxyhydrogen flame. In the flame, droplet-like primary particles form, some of which fuse together in the colder region of the flame to create large chain-like aggregates. These harden completely in the colder flame region, and in turn become attached to each other to yield agglomerates. Chemically, HDK® pyrogenic silica is highly pure amorphous silicon dioxide and has the appearance of a loose white powder. Just 18 g would cover an area the size of a soccer pitch! HDK® is completely non-toxic to humans and the environment.

One Plant, One Loop: The Integrated Production System

HDK® is a key component of the integrated production system – which is one of WACKER’s major strengths. Basically, integrated production involves using the byproducts from one stage as starting materials for making other products. This ensures that the byproducts are used to the fullest extent possible and that raw materials are recycled within a closed loop. Compared with open-ended production processes, integrated production lowers manufacturing costs and conserves both energy and resources. The raw materials are used in a sustainable manner while environmental protection is integrated into production.

HDK® in the integrated production system:

  • in the chlorine-HCl system, the toxic chlorinated intermediate products are converted into nontoxic byproducts, such as hyperpure silicon, silicones or pyrogenic silica. In the integrated material loop, both hydrogen chloride and some of the energy in the form of heating steam are recovered. The production of HDK® markedly enhances polysilicon production by providing an outlet for byproducts which are used to make HDK®. This closes the loops there and conserves both energy and resources.
  • in the integrated silicon system, over 3,000 silicone products, pyrogenic silica and polysilicon are produced from silicon, methanol and common salt.

HDK® – From Quartz Sand to Silica

Consistent Quality. Worldwide.

WACKER produces HDK® pyrogenic silica at Burghausen and Nünchritz in Germany and Zhangjiagang in China. A further plant will come on stream in Charleston, Tennessee/USA, in 2019. The processes and technologies employed at all these sites are identical. Testing and packing are also conducted to the same high quality standards worldwide. That is how we can guarantee supplies of exceptionally pure HDK® in consistently high quality at any time anywhere in the world.

Find out more about HDK® from WACKER.

WACKER offers a wide range of hydrophilic and hydrophilic HDK® grades and HDK® dispersions for all kinds of applications. You will find more details in our product section.

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