Application of Aluminum Pigment Technology in Ink Coatings (II)

Preparation of Aluminum Pre-Dispersion: All aluminum pastes need to be pre-dispersed in a suitable solvent to obtain a pigment paste. The pigment paste must be added to the coating system after all other components that require higher shear have been added.

Wetting agents: In many cases, wetting agents should be added to the metal flake pigment paste to assist in the wetting of flake pigments.

pH and Neutralization: If water-soluble resins are used, it is not appropriate to use too basic neutralizers. For example, it is necessary to avoid the use of aqueous ammonia that tends to react with aluminum; it is preferable to use, for example, DMEA (dimethylacetamide). Or the amines of TEA (triethanolamine) neutralize the pH. In general, the pH should not be higher than 9, ideally between 7-8.

Alignment of metallic flake pigments: This is a very important aspect of metallic effect coatings. Poor orientation will reduce the brightness and flop of the paint. The more the flake pigments can be aligned parallel to the substrate, the better the metallic effect of the pigments. Polyethylene wax dispersions can be added to waterborne coatings to improve their orientation properties.