7 performance indicators for pigments used in coatings

Color of pigment
The color of pigment is the result of selective absorption of light of different wavelengths in visible light, which is affected by the physical properties such as crystalline shape, particle size and dispersion properties, such as iron oxide red color, which changes from orange-red to fuchsia as the particle size increases; The color of the pigment is also affected by the light that shines on it, for example, in the dark, the pigment does not show any color, the color in strong light is brighter than in the dark light, and the same pigment in different light sources (e.g. sunlight, incandescent light, fluorescence, etc.) can also show different colors.
coloring force
the coloring force of a pigment refers to the ability of one pigment to appear dark when mixed with another pigment. Tune the same color, the stronger the coloring force, the less the amount of color paste, the less water resistance of the color paste coating and the impact of film performance is

. So the same color, the quality of products from different manufacturers will be very different. The strength and weakness of pigment coloring force not only depends on its properties, but also has a certain relationship with its dispersion degree. The greater the dispersion, the stronger the coloring force.
resistance to light and water
pigments will produce certain changes in color to varying degrees under the effect of light. Inoromic pigments will gradually darken their color in the long-term sunlight, and some pigments will also produce powdering under the effect of ultraviolet light in the sun. Exterior paint should be selected light weather-resistant pigments, generally more than 7 to 8 levels, 8 levels of the best, weather resistance is greater than 4 to 5 levels, 5 levels of the best. Inorganic pigments such as iron oxide system light resistance is generally very good, the corresponding color of the paint color preservation is very good; The higher the light resistance of organic pigments, the higher the price, the lower the light resistance of each level, the price and weather protection color will be very different, light resistance ≤6, weather resistance≤3, the price will be more than 4 times different. So the outer wall paint, especially organic color paint is a price of a cent.
the coating force
the pigment in the coating film can cover the surface of the coated object, so that the substrate cover can no longer be revealed through the coating film. The strength of pigment cover mainly depends on such factors as recline rate, light absorption ability, crystal structure, and dispersion. The ability of the pigment to cover depends not only on the ability of the coating to reflect light, but also on its ability to absorb light shining on the surface of the coating. Carbon black, for example, absorbs the light that shines on it completely, so it has a very strong cover. The strength of the opaque color pigment cover also depends on their selective absorption of light. Pigments are evenly dispersed in the base material, its particle size is small, larger than the surface area, and therefore the ability to cover is also increased, but if the size of pigment particle size is equal to half the wavelength of light, light will pass through the particles without refraction, and make the particles transparent. The higher the crystallization of the pigment, the stronger its cover. The masking force of the mixed pigment cannot be calculated according to the addition law according to the covering force of the components of the mixture, in fact, the cover force of most mixed pigments is higher than the calculated value. Therefore, mixing pigments with fillers in the appropriate proportions does not affect their masking power and is conducive to reducing costs. The cover power of the coating is high, the area of the coating is high, and the cost of the project is low.
The cover force of commonly used pigments
dispersion and adaptability
so-called pigment dispersion refers to the accumulation of pigment particles in the paint base material is easily dispersed and its dispersed state, it is affected by pigment performance, preparation methods, particle size and particle size distribution and other factors. The dispersion of pigments has obvious effects on the cover and coloring power of pigments, as well as on the physicophysic performance of coating film. The adaptability of pigments, which is particularly important for emulsion-type architectural coatings. Due to the different pigment types, the role of pigments will also show a certain degree of difference, organic pigments this tendency is more obvious. Pigments are poorly dispersed in the coating and poorly matched with the coating, which can potentially flocculate or even fade.the fineness of
fineness
color paste is not the finer the better, because pigments such as indistinct blue, indistinct green is itself a small molecular pigment, fineness is too small, particle size difference is large, poor dispersion, and paint compatible is not good, the cost of color adjustment increases, but also will lead to floating hair flowers.
acid-
acid-resistant pigments is also an important performance indicator for their use in architectural coatings. For example, iron blue or chromium jaundate will break down, gray calcium powder and calcium carbonate will react, so use should pay attention to choice. If the selection 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 faded powder pan-alkali and other phenomena, so customers choose paint and latex paint color must pay attention to the choice.