Лако-красочные материалы — производство

1. Self-Crosslinking Systems Numerous possibilities exist for the manufacture of polymers with latent coreactive sites<10). The introduction of built in functional groups onto the surface of the polyurethane particle and proprietary reactive groups copolymerised into the backbone of the acrylic and buried deep into the core of the acrylic phase are the usual techniques for […]

Abrasion and impact resistance of acrylic coatings can be improved with the addition of up to 30% of a water borne polyurethane. The addition of a polyurethane dispersion as a physical blend improves the inherent film strength and film formation of the acrylic latices. Polyurethanes generally have better film forming properties because of their lower […]

The use of water borne coatings on steel can, in certain instances, lead to flash rusting, which is the rapid and irreversible formation of rust. This is especially true under conditions of high humidity, where the water component of the formulation remains in contact with the metal for extended periods of time, when the evaporation […]

Most emulsions are low viscosity liquids. Even with pigments and extenders, the viscosity is still too low for nearly all application methods. Thus, it is necessary to add materials to increase the viscosity of the finished products and possibly to change its rheology. Traditionally, hydroxy ethyl cellulose was the most commonly used thickener (viscosity increaser […]

The presence of surfactant in a water-based medium makes the system susceptible to foaming. The correct choice of defoamer will be dependent upon the compatibihty of the additive. Its efficiency is determined by trial and error and most importantly by experience. Defoamers are most effective when dispersed in the mill base stage of the formulation. […]

It is difficult, if not impossible, to accurately define the difference between a dispersant and a wetting aid. One simple, but general, definition is that dispersants keep the dispersed particles apart, whereas wetting aids reduce surface tension which may permit dispersion. A wetting aid can be a dispersant, but a dispersant cannot be a wetting […]

These are generally higher in viscosity than the emulsions and are used for specific purposes. A volatile amine is used for neutralisation. When it leaves the film, the film becomes insoluble. These materials, especially viscosity modifiers, dissolve as the pH changes. As a general rule an acid value of 50mg KOH/g is required in order […]

These dispersions are generally low viscosity liquids, with solids in the range of 35-50% and appearance ranging between opalescent and white, depending on the make up and particle size of the emulsion. Many commercially available emulsions contain coalescent solvents. Most emulsions contain some surfactant added to stabilise the emulsion and to form micelles. The surfactant, […]

Emulsion polymers differ from solution types in that the polymer takes the form of a fine particle suspension (typically from 0.03 to 0.3 pm) dispersed in water. There are two major classes of waterborne polymer colloids(9) available, namely; • aqueous polymer dispersions prepared by emulsion polymerisation • dispersions of preformed polymers into water by solubilisation […]

Both the emulsion polymer and paint industry guard their industrial secrets. Polymer manufacturers will state the type of polymer and surfactant or colloid, but will not divulge quantities of either monomer ratios or surfactant concentrations. They will say whether surfactants are anionic or nonionic, but will not divulge the chemical nature of individual surfactants used, […]