Transparency and uncompromising scratch resistance

In radiation curing coatings, high transparency and scratch resistance go together perfectly - with nanocomposites made by nanoresins. And that is by no means the end of the story: a substantial number of further important properties in radiation curing coatings can be improved with Nanocryl® C and Nanopox® C.

Product overview
Improvements to properties
How it works

Product overview [back]

Note: Further Nanocryl® C products and mixtures for special applications are available on request. Please contact our application specialists.

Improvements to properties [back]

Nanocryl® C products are colloidal silica sols in various unsaturated (meth-)acrylate binding agents. These products are highly transparent, low viscous and do not show sedimentation, i.e. the processability remains essentially unchanged in comparison to the respective base resin. In this way the specific advantages of organic and inorganic materials can be combined almost perfectly.

Important properties which can be improved in radiation-curing formulations through the use of Nanocryl® are:

• significantly improved scratch and abrasion resistance
• no reduction in transparency and gloss for the coating
• barrier effect against gases, water vapor and solvents
• increased weathering resistance and inhibited thermal aging
• reduced cure shrinkage and heat of reaction
• reduced thermal expansion and internal stresses
• increased tear resistance, fracture toughness and modulus
• improved adhesion to a large number of inorganic substrates
  (e.g. glass, aluminium)
• improved dirt resistance against inorganic impurities (e.g. soot) by a more hydrophilic surface
• improvement to other desired properties such as: thermal stability, stain-resistance, heat conductivity, dielectric properties

Nanocryl® C is used in applications where these property improvements are desired or necessary, without compromising processability by an excessive viscosity increase (as known from e.g. fumed silica). The fact that this is possible without loss of optical clarity makes Nanocryl® C particularly suitable for transparent formulations. Highly scratch-resistant (e.g. against steel wool), transparent lacquers for plastic (e.g. PC, PMMA, PET) or wood are known as examples.

How it works [back]

Nanocryl® C products are colloidal dispersions of up to 50 wt% amorphous silica in a wide range of conventional unsaturated (meth-)acrylate monomers and oligomers. The dispersed phase consists of surface-modified, spherically shaped SiO2 nanoparticles with diameters of 20 nm and an very narrow particle size distribution (Fig. 1).

Figure 1:  Particle size distribution (determined by SANS)

The SiO2 spheres are distributed homogenously and agglomerate-free in the resin matrix (Fig. 2). This results in a very low viscosity of the dispersion despite SiO2 contents of up to 50 wt%.

Figure 2:  TEM – images of a cured Nanopox® sample with 5% silica nanoparticles

The nanoparticles are synthesized from aqueous sodium silicate solution in a chemical process. In this unique process the binding agent is not damaged, in contrast to processes in which powdered fillers are dispersed with dissolvers or other machines using high shear forces.

For further details, please contact our application specialists.