| 摘要 |
A thickener suitable for use with coating masses containing a water dilutable or compatible binder is composed of a hetero-polysaccharide reacted with an aminofunctional silane. The relationship between the amounts of hetero-polysaccharide and silane lies in the range of 10:1 to 1:5 parts by weight, preferably in the range 5:1 to 1:2. Preferably, the hetero-polysaccharide is swollen in water and contains between 1 - 3% by weight of solid matter and the aminofunctional silane is an aminoalkyltrialkoxysilane. Preferably, the proportion of thickener added to the coating mass is 0.1 - 20% by weight of solid matter, in relation to the total weight of the coating mass. Other additives may be added to the thickener in order to improve its rheological effects, such as a primary or secondary amine, preferably a diamine, in an amount not exceeding 10% by weight, and/or an expandable activated layered silicate, preferably bentonite, montmorillonite, illite, vermiculite and/or smectite, in amounts not exceeding 25% by weight, and/or a chelate compound, preferably titanium chelate and/or zirconium chelate in an amount not exceeding 10% by weight. These additive amounts refer always to the total weight of the coating mass. This thickener has proved to be remarkably effective in imparting thixotropic properties to coating masses having as binder a dispersion of synthetic resin in water, a water-soluble synthetic resin and/or a synthetic resin emulsion of the oil/water or water/oil type, mixed with a solvent if necessary. The thickener can be added to the coating mass as a reactive product ready for use, but it can also be formed in situ by adding to the coating mass one reactant after the other. |
