| 摘要 |
<p>Comprises the use of a gel-forming regulator agent based on the phosphorated derivatives of alkanolamines which controls at will the initial acceleration or slowing of gelling rate in systems based essentially on a preferably vinyl polymer in aqueous dispersion, cellulose and/or acrylic thickeners, and a gelling agent of the titanium chelate type or of the colloidal silica type with a high Na2O content, this control being an obvious advantage of an industrial and commercial nature. The compositions affected by this control will include the pigments, extenders, coalescing agents, moisturisers, preservatives, etc., necessary for providing the necessary opacity and stability characteristics, the rheological properties of these systems being those specified for a viscosity of between 8,000 and 30,000 poises at 1/2 rpm in a Brookfield viscometer and Helipath spindle, and a flow threshold of 150-350 g measured in a Stormer using 52 cm2 paddles. These systems which have a consistency which will maintain the shape of the vessel when at rest become superficially fluid under mild shearing such as when a roller is passed over their surfaces, impregnating it and making it possible to apply the coating like any paint without drops or splashes. These compositions are prepared by dispersing the pigments and extenders together with the moisturiser- dispersants and hydroxylated thickeners, using a toothed disk agitator rotating at 900-1000 rpm; the polymer and the remaining ingredients are then added reducing the velocity to the minimum possible and cooling to less than 28 degree C; checking and colouring of the base are then performed as the gelling agent is added by agitating at low velocity for 10-15 minutes, followed by immediate packaging.</p> |
