GB740776A - Improvements in and relating to processes of preparing pigmented coating products - Google Patents

Abstract

A process of preparing pigmented coating compositions such as paints, lacquers, enamels, printing products, and primers comprises preparing a mixture containing all of the pigments, a large proportion of the solvents (more than 25 per cent of that in the final composition) and a quantity of resinous binder equal to 0.5-5 per cent by weight relative to the pigment, vigorously agitating the mixture with a rotative motion until the pigment is wetted and dispersed and then introducing the remainder of the constituents. The resinous binder may be a synthetic resin such as glycerophthalic or urea-formaldehyde resin. The solvent may be white spirit, alcohols such as butyl alcohol, ketones, esters such as acetates, or aromatic solvents such as toluene, xylene or naphtha. The stirring may be carried out with a rotary agitator which may comprise a flat-bottom cylindrical vessel having disposed one centimetre from the bottom, a rotor having a double row of teeth rotating inside a system of fixed blades, and rotating preferably at a speed between 500 and 3000 r.p.m. In an example, 480 parts solvent (one-third naphtha solvent, two-thirds white spirit), 500 parts titanic oxide and 5 parts glycero-phthalic resin in 50 per cent solution in the same solvent mixture are stirred together for one hour when a homogeneous dispersion is obtained. 2000 parts of the same binder solution and 20 parts of cobalt drier solution are then added, the agitator being allowed to run for a further 5 minutes which gave complete homogenization. Other examples describe a similar process but using yellow iron oxide or medium chrome yellow as the pigment and different proportions of ingredients.ALSO:A process of preparing pigmented coating compositions such as paints, lacquers, enamels, printing products, and primers comprises preparing a mixture containing all of the pigments, a large proportion of the solvents (more than 25 per cent of that in the final composition) and a quantity of resinous binder equal to 0.5-5 per cent by weight relative to the pigment, vigorously agitating the mixture with a rotative motion until the pigment is wetted and dispersed and then introducing the remainder of the constituents. The resinous binder may be a synthetic resin such as glycerophthalic or urea-formaldehyde resin. The solvent may be white spirit, alcohols such as butyl alcohol, ketones, esters such as acetates, or aromatic solvents such as toluene, xylene or naphtha. The stirring may be carried out with a rotary agitator which may comprise a flat-bottom cylindrical vessel having disposed one centimetre from the bottom a rotor having a double row of teeth rotating inside a system of fixed blades and rotating preferably at a speed between 500 and 3000 r.p.m. In an example, 480 parts solvent (one third naphtha solvent, two thirds white spirit), 500 parts titanic oxide and 5 parts glycero-phthalic resin in 50 per cent solution in the same solvent mixture are stirred together for one hour when a homogeneous dispersion is obtained. 2000 parts of the same binder solution and 20 parts of cobalt drier solution are then added, the agitator being allowed to run for a further 5 minutes which gives complete homogenization. Other examples describe a similar process but using yellow iron oxide or medium chrome yellow as the pigment and different proportions of ingredients.