Using a high-pressure homogeniser to disperse optical pigments, thereby enhancing the product’s colour performance and stability

Optical pigments are a class of functional pigments with unique optical structures. Thanks to their colour-shifting properties, high gloss and excellent weather resistance, they are widely used in high-end cosmetics, automotive coatings, and printing and packaging. Their core value lies in the unique visual effects they produce through the refraction and reflection of light, whilst the dispersion state of the particles directly influences the product’s final optical performance and stability.

As the demand for ‘visual texture’ in high-end manufacturing increases, the application of optical pigments is becoming increasingly sophisticated, placing stringent requirements on particle size uniformity and crystal integrity. Traditional ball milling methods are prone to causing particle agglomeration and crystal damage, thereby diminishing the optical effects; solvent dispersion methods, meanwhile, carry the risk of residual solvents, which are not only environmentally unfriendly but may also compromise the stability of the product system, making it difficult to meet the production requirements of high-end applications (such as original equipment manufacturer (OEM) automotive paints and luxury packaging).

Experiment

 The optical pigment slurry was processed using a high-pressure homogeniser, undergoing multiple cycles of homogenisation at a pressure of 1,200 bar. Following treatment, the pigment particles were uniformly dispersed, with no sedimentation or agglomeration, and the stability of the system was significantly improved. The particle size decreased from an initial 190.8 nm to 138.1 nm, the transparency of the pigment suspension improved, the colours became more vivid and rich, and the gloss was markedly enhanced.

Fig.1 Initial particle size

Fig.2: Experimental particle size

Fig.3  Optical pigment samples after the experiment