Color paste essential tips
1, water-based color paste performance and use requirements?
1.1 Performance requirements: color paste as high as possible pigment content, coloring power, covering power, resistance (light resistance, weather resistance, acid resistance, alkali resistance, temperature resistance, resistance to other media, etc.), good dispersion, fluidity, color, batch stability (reproducibility) and compatibility with a variety of systems, high cost performance.
1.2 Storage stability requirements: water-based color paste storage process does not grain, does not flocculate, no obvious delamination, does not sink hard bottom, easy to stir evenly.
1.3 Environmental requirements: no or low content of organic volatile organic compounds (VOC), APEO, heavy metals.
2、What is relative coloring power?
Relative coloring power refers to the coloring strength of the color paste to be examined relative to the standard color paste. For the comparison of water-based color paste, coloring strength is an important index, which reflects the color concentration of color paste, color spreading performance and pigment dispersion flocculation. The coloring strength is generally tested for dark color (1/1ST washout) and light color (1/25ST washout). The coloring strength of the color paste to be examined can generally be measured by a spectrophotometer or calculated according to the formula.
3、Compatibility between color paste and emulsion paint
The compatibility of color paste and emulsion paint mainly depends on the dispersibility of the color paste itself, anti-flocculation, pigment concentration, viscosity, grinding resin and emulsion paint dispersion stability, viscosity, particle size, the selected dispersive wetting system, emulsion, thickening system and so on. The compatibility of color paste and emulsion paint is the key to the spreading of color paint, flocculation, floating color, blooming and other film defects.
Compatibility test method of color paste and emulsion paint: finger study. Add appropriate amount of color paste in latex paint, mix well, scrape coated on white cardboard, until the surface of the film is not completely dry before (do not carry out when the surface of the film is wet), use your forefinger to finger research in the same direction for 5~6 times, compare the finger research area and non-finger research area color differences, to determine the compatibility of good or bad.
4、How to choose the color paste?
4.1 According to the outdoor and indoor use of different environments, the choice of color paste has an external color paste and internal color paste, external color paste light resistance, weather resistance are required to be very high (1/25 lightening color light resistance should be in the 7 ~ 8 level, weather resistance should be in the 4 ~ 5 level), while the internal use of the color paste does not have a very high requirement. So the external color paste can be used internally, but the internal color paste can never be used externally.
4.2 According to the different acid and alkaline resistance of the color paste, choose the color paste with good acid and alkaline resistance for the specific environment of the object of use.
4.3 According to the compatibility of color paste and paint system, use the color paste with good compatibility.
4.4 According to the coloring strength of the color paste in the paint system, select the color paste with high coloring strength and good cost performance.
4.5 Consider the matching between the color paste and the color paste to choose the color paste, and do the matching test before mixing the color pastes of different manufacturers.
Considering the above factors, the color paste for outdoor use should follow the principle of choosing color paste with good light resistance, good weather resistance and good chemical medium, and prefer the color system of iron oxide pigment or similar color system when choosing color, and the organic bright color system should be chosen with the light resistance of grade 7-8, weather resistance of grade 4-5, and acid resistance and alkaline resistance of grade 4-5 color paste. Indoor use of color paste to follow the principle of good compatibility, good color, low cost, cost-effective.
5、How to test the light resistance and weather resistance of color paste?
Color paste light resistance, weatherability testing can be carried out through natural outdoor exposure and artificial accelerated aging in two ways, outdoor exposure is generally to choose a location with typical climatic conditions, and the test cycle is long. Nowadays, artificial accelerated aging test is generally chosen to obtain the results of light resistance and weathering resistance similar to the natural conditions.
Light resistance: Use outdoor acrylic emulsion paint made of 1/1 and 1/25 ISO standard depth color samples for exposure. Or using Q-UV light meter test 500 hours, using 1-8 grade blue wool ruler and standard color samples at the same time exposure, resulting in color difference to rating, 1 worst, 8 good.
Weathering: Use outdoor acrylic emulsion paint made of 1/1 and 1/25 ISO standard depth color samples for exposure. Or use ATLAS artificial aging instrument exposure 500 hours, using ISO gray card for color difference rating, class 1 is the worst, class 5 is the best. Can also be measured by spectrophotometer aging before and after the sample color difference to rating.
6、What is the chemical resistance of the color paste?
The chemical medium resistance of water-based color paste mainly refers to the acid and alkali resistance of the selected pigment. For different applications, the acid and alkali resistance indexes should be considered when selecting water-based color paste, and the color paste with good acid and alkali resistance should be considered when used for the exterior of the building.
Acid and alkali resistance test method: the color paint plate, with a filter paper saturated with 2% hydrochloric acid or saturated calcium hydroxide solution covering the surface of the paint film, covered with a glass plate, and add a weight, stand for 24 hours, check the
