Method for providing an aqueous composition with retroreflective properties

A method for providing a composition selected from the group consisting of aqueous pastes, inks, paints and coating formulations with retroreflective properties, said method comprising the steps of:

• a) providing an aqueous paste, ink, paint or coating formulation without retroreflective properties, said aqueous paste, ink, paint or coating formulation having a viscosity η1 of between 0.25 and 1000 Pa·s at a shear rate of 0.01 s−1;
• b) providing an aqueous pseudoplastic gel composition having a first viscosity η2 at a shear rate of 0.01 s−1 of between 5 and 250 Pa·s and a second viscosity η3 at a shear rate of 100 s−1 that is between 10 and 1000 times lower than the first viscosity η2, wherein the aqueous pseudoplastic gel composition consists of, based on the total weight of the aqueous pseudoplastic gel composition:
• 15-39.85 wt. % of water;
• 60-80 wt. % of spherical glass beads having a median particle diameter D50, as measured with laser diffraction, between 5 and 1500 μm, and a refractive index, measured at a wavelength λ of 589 nm, between 1.8 and 2.8, wherein optionally at least part of the spherical glass beads are hemispherically coated with a light-reflective coating;
• 0.15-2.5 wt. % of a thickener;
• and
• 0-5 wt. % of one or more further ingredients;
• c) admixing the aqueous paste, ink, paint or coating formulation provided in step (a) with the aqueous pseudoplastic gel composition provided in step (b) in a weight ratio of between 30:70 to 70:30;
• and
• d) admixing the mixture obtained in step (c) with 0-2 wt. %, based on the total weight of the aqueous paste, ink, paint or coating formulation with retroreflective properties, of a thickener, to provide an aqueous paste, ink, paint or coating formulation with retroreflective properties,
• wherein the viscosities η1, η2 and η3 are measured with a rheometer with a plate-plate geometry and a gap distance of 0.5 mm at a temperature of 25° C.