The effect of colour pastes on coatings
The use of colour pastes in paints is very common, but there are now very many different colour paste products available. So it is necessary to understand the impact of colour pastes on the paint to facilitate the selection of the right colour paste.
1、Solvent resistance
The colour paste is prepared by the resin with good compatibility, the main resin of the colour paste is also relatively easy to dissolve in organic solvents, thus affecting the solvent resistance of the final coating film.
2、Colouring power or colouring strength
Paint colouring strength indicates the intensity of the colour hue in the application surface. Tune the same colour, the stronger the colouring strength, the less the amount of colour paste, the lower the degree of water resistance of the colour paste coating and the impact of the film performance is smaller. So the same colour, the quality of the products of different manufacturers will be very different. The strength of the colouring power depends not only on the nature of the pigment, but also on its degree of dispersion. The greater the dispersion of the pigments in the colour paste, the stronger the colouring power. To achieve a better dispersion of the pigments in the colour paste, a good dispersant and the correct grinding process are required. Currently, polymeric dispersants are used more often. Poor pigment dispersion not only affects the colour phase and colouring power, but also the potential for flocculation and even fading of the paint due to poor matching with the paint.
Colour pastes with high colouring power will also facilitate increased production. For example, by using a highly concentrated colourant with high tinting power, more products can be produced with the same weight of ground colourant. The energy and cost of production will also be reduced.
3、Fineness
The fineness of the pigment in the colour paste will affect the colouring power and have an impact on the gloss of the coating film and other properties. The finer the pigment in the colour paste, the higher the colouring power will be, but not the finer the colour paste, the better. The finer the pigment, the higher the colouring power. In addition, like phthalocyanine blue, phthalocyanine green pigment itself is small molecule pigment, fineness is too small, particle size difference, poor dispersion, and paint compatibility is not good, colour mixing costs increase, and also lead to floating colour flower.
4、Acid and alkali resistance
Acid and alkali resistance in architectural coatings is an important performance indicator. For example, iron blue or chrome yellow will decompose when it meets alkali, and calcium grey powder and calcium carbonate will react when they meet acid, so attention should be paid to the choice when using them. If you choose the price is very low, non-professional production of latex paint manufacturers produce yellow, blue, etc., because the price is very low or do not know its pigment performance, latex paint will soon have fading chalking alkali and other phenomena. Colour paste is widely used, so we need to choose the right pigment for different fields to prepare colour paste, customers need to pay attention to the choice of colour paste for paint.
5、Compatibility
Before using the colour paste for paint, compatibility test is needed, such as floating colour observation, finger research test, etc. Poor compatibility of the colour paste not only leads to paint floating colour flowering, and will appear fading and other phenomena. In addition, the leveling of the paint after adding the colour paste will also be affected by the compatibility.
