CIUPL has the pleasure in offering Aluminium Pigments for the Coating / Plastic applications, from our overseas Principal - M/s Silberline Asia Pacific Inc., Singapore.

ALUMINIUM PIGMENTS :
Formulation Guidelines for Leafing and Non - Leafing pigments

Aluminium Pigments by their very nature are rather malleable and somewhat fragile flakes. They are prone to deterioration if subjected to high - speed mixing or if they undergo continuous and harsh circulation in a coating system. The recommended dispersions technique involves the addition of sufficient vehicle or solvent to the aluminium paste and with slow - speed mixing, develop a thick, creamlike consistency. Once the thick slurry is uniform, additional solvent and vehicle can be incorporated to complete the letdown. Severe dispersion technique will destroy the integrity of the flake and result in poor aesthetics which could include a seedy finish, dark colour, low opacity or poor metallic travel.

The choice of the vehicle system and its components will largely depend on the end use for the coating. However, the manufacture of any metallic coating should adhere to the basic formulation parameters listed.

Vehicle Selection :

Vehicle selection is generally determined through a combination of cost analysis and end use of coating. Exterior versus interior usage, substrate coated, chemical and moisture resistance, environment restraints and speed of dry are only a few of the factors to be considered. A wide range of vehicles can be employed for leafing and non-leafing system including oleoresinous varnishes, acrylics, alkyds, epoxies, urethanes and aqueous systems. Generally, any vehicle that will be compatible with the mineral spirits carrier of the aluminium paste and will not chemically interact to attack the aluminium flake should be suitable. Aluminium metal is amphoteric and as such the acid number of vehicle systems should be held below seven.

Solvent Selection :

Solvent Selection will largely depend on the vehicle system chosen for the formulation. Formulations with the non-leafing pigments are far less restrictive in their solvent requirement than are the leafing pigments. Non-leafing pigments can utilize a wide range of polar and non-polar solvents. Leafing aluminium pigments, however, require non-polar solvents only, including preferably and alphatic or aromatic hydrocarbon with high surface tension ( atleast 27 dynes / cm ). Polar solvents, including the ketones and alcohols, will interfere with, and effectively remove, the fatty acid lubricant on the flake, thus deleafing the pigments. The preferred aliphatic and aromatic solvents, such as mineral spirit, xylol, toluol and high flash naphtha, provide excellent leafing characteristics.

Water, a common contaminant in most solvents should be kept to an absoloute minimum in a coating system. Water reacts with aluminium metal to yield hydrogen gas. Studies have shown that moisture level in excess of 0.15 % in the finish coating can generate sufficient gas to bulge or pop the end of the can.

Silberline provides over 200 different types of Aluminium pigments to a variety of industries.

For a more comprehensive listing, technical data, or samples, please submit a literature request.

We kindly request you to go through the individual product data sheet and for additional / further details, we will be please to furnish you the desired information / clarification from ushavi@bom5.vsnl.net.in