Hielscher - Ultrasound Technology

In paint and coatings nanomaterials fulfill decorative needs (e.g. color and gloss), functional purposes (e.g. conductivity, microbial inactivation) and improve protection (e.g. scratch resistance, UV stability) of paints and coatings. In particular nano-size metal-oxides, such as TiO2 and ZnO or Alumina, Ceria and Silica and nano-size pigments find application in new paint and coating formulations.

Nanomaterials are materials of less than 100nm in size. They are quickly progressing into the formulations of paints, inks and coatings. Nanomaterials fall into three broad categories: metal oxides, nanoclays, and carbon nanotubes. This small matter has an impact on many disciplines, such as physics, chemistry and biology.

When matter is reduced in size it changes its characteristics, such as color and interaction with other matter such as chemical reactivity. The change in the characteristics is caused by the change of the electronic properties. By the particle size reduction, the surface area of the material is increased. Due to this, a higher percentage of the atoms can interact with other matter, e.g. with the matrix of resins. Surface activity is a key aspect of nanomaterials. Agglomeration and aggregation blocks surface area from contact with other matter. Only well dispersed or single-dispersed particles allow to utilize the full beneficial potential of the matter. In result good dispersing reduces the quantity of nanomaterials needed to achieve the same effects. As most nanomaterials are still fairly expensive, this aspect is of high importance for the commercialization of product formulations containing nanomaterials. Today, many nanomaterials are produced in a dry process. As a result, the particles need to be mixed into liquid formulations. This is where most nanoparticles form agglomerates during the wetting. Especially carbon nanotubes are very cohesive making it difficult to disperse them into liquids, such as water, ethanol, oil, polymer or epoxy resin. Conventional processing devices, e.g. high-shear or rotor-stator mixers, high-pressure homogenizers or colloid and disk mills fall short in separating the nanoparticles into discrete particles. In particular for small matter from several nanometers to couple of microns, ultrasonic cavitation is very effective in breaking agglomerates, aggregates and even primaries. When ultrasound is being used for the milling of high concentration batches, the liquid jets streams resulting from ultrasonic cavitation, make the particles collide with each other at velocities of up to 1000km/h. This breaks van der Waals forces in agglomerates and even primary particles.

Ultrasound can be applied for the effective dispersing of high concentration master-batches – processing low and high viscosity liquids. This makes ultrasound good processing solution for paints and coatings, based on different media, such as water, resin or oil.

Hielscher ultrasonic processors and flow cells for deagglomeration and dispersion are available for laboratory and production level. The industrial systems can easily be retrofitted to work inline at high throughput. For the research and for the testing of this process as well as for many sonochemical processes we recommend laboratory devices or the Hielscher UIP1000 set.

Hielscher offers a broad range of ultrasonic devices and accessories for the efficient dispersing of nanomaterials in paints, inks and coatings.

• Compact laboratory devices of up to 400 watts power
  These devices are mainly used for sample preparation or initial feasibility studies and are available for rental.
• 500 and 1,000 and 2,000 watts ultrasonic processors like the UIP1000 set with flow cell and various booster horns and sonotrodes can process larger volume streams.
  Devices like this are used in the optimization of the parameters (like: amplitude, operational pressure, flow rate etc.) in bench-top or pilot plant scale.
• Ultrasonic processors of 2, 4, 8 and 16kW and larger clusters of several such units can process production volume streams at almost any level.

Bench top equipment is available for rental at good conditions to run process trials. Results of such trials can be scaled linear to production level – reducing the risk and costs involved in the process development. We will be glad to assist you online, on the phone or personally. Please find our addresses here, or use the form below.