Introduction to the use of water-based color paste!
I. Introduction of water-based color paste
Water-based color paste refers to the organic or inorganic pigments under the wetting and dispersing effect of surfactants (water-soluble resin can also be added), forming a homogeneous, stable, with a certain degree of fluidity or thixotropic fluidity, strong coloring strength of concentrated pigment paste. There are two kinds of water-based color paste systems: one is a high pigment content resin-free system; the other is a low pigment content resin (general resin, other single resin) system. The former has high pigment concentration, strong coloring power, good color spreading performance, good compatibility, thixotropic fluidity, generally does not cause floating color and flowering, reasonable choice of additives, and is universal. The latter has relatively low pigment concentration, but has good coloring power, good color spreading, stable fluidity and viscosity, the system contains resin, compatibility needs to be tested, otherwise it will easily lead to floating color and flowering.
Second, the main technical indicators of color paste
1、The quality of color powder in color paste (mainly depends on its international pigment number)
International pigment number: simply understand the unified pigment code according to the different molecular structure of the color powder, the pigment number determines the light resistance (weather resistance) and chemical resistance (acid and alkaline resistance) of the color paste, and also determines the general color phase of the color paste, because the production process of each color paste company is not the same, the color phase of the color paste may have subtle differences.
Commonly used international pigment code table
Color CI Pigment English Name Chinese Name
Titanium White 6 Dioxide Titanium
Black 11 Iron Oxide Red Iron Black
Black 7 Carbon Black Carbon Black
Ultramarine Blue 29 Ultramarine Ultramarine
Red 168 Antharuinore Red Anthraquinone Red
Big Red Red 112 Monoaz Red Monoaz Red / Amide Condensation Red
Ortho Red Red 254 DPP Red BO DPP Red
Coral Red Red 255 DPP Red BO Coral DPP Coral Red
Iron Red Red 101 Iron Oxide Red Iron Red
Light Yellow Yellow 1 Monoazo Yellow
Yellow 3 Monoaz Yellow Monoaz Yellow
Bright Yellow Yellow 109 Isoindolinone
Iron Yellow 42 Iron Oxide Yellow Iron Yellow
Lemon Yellow 74 Monoaz Yellow Monoazo/aramide Yellow
Dark Yellow 83 Disazo Yellow Bis-azo Yellow
Bright Yellow Yellow 97 Monoazo
Yellow 138 Quinoline Yellow Quinoline Yellow
Yellow 110 Isoindolinone Yellow
Golden Yellow Yellow 153 Nickel Complex
Green Gold Yellow 154 Benzimida Zolone Benzopyrazolone Yellow
Blue 15:1 Phthalocyanine Green Phthalocyanine Blue
Blue 15:3 Phthalocyanine Green Phthalocyanine Blue
Blue Blue 15:4 Phthalocyanine Green Phthalocyanine Blue
Green Green 36 Phthalocyanine Green Phthalocyanine Green
Green Green 7 Phthalocyanine Green Phthalocyanine Green
Violet 23 Oxazine Violet Dioxazine Violet
Violet 19 Quinacridone Violet 喹吖啶one Violet
Orange 5 Dinitroaniline Orange
Orange Orange 43
Orange 73 DPP Orange DPP Orange
Brown 6 Iron Oxide Brown Iron Brown
The international pigment number is an important basis for the correspondence of the product models of different color paste companies. When we check the quality of different brands, we should choose the same pigment number of different manufacturers for comparison. Any color paste company must provide its customers with the international pigment number of its color paste. To fully understand the quality of color powder is the most important basis for emulsion paint manufacturers to choose color paste for different application fields (such as interior and exterior wall color paint).
2、The coloring strength of color paste (coloring power)
Tinting power refers to the white latex paint containing 100 grams of titanium dioxide, to 1/25 standard color depth, the number of grams of a color paste used, the less the amount of color paste, the stronger the coloring power. For the comparison of water-based color paste, coloring strength is an important indicator, which reflects the color concentration of the color paste, color performance and pigment dispersion flocculation. The stronger the coloring power of the color paste, the less the amount of color paste used for color mixing, the less the impact on the performance of the coating film, and the lower the cost of color mixing.
3、Color difference ΔE
The stability and color reproducibility of the color paste is mainly reflected in two aspects: coloring power and color difference. The color difference of color paste includes the color difference between different production batches of the same color paste and the color difference between different packages of the same batch. The size of the color difference is expressed by ΔE, including color hue, lightness and darkness, saturation. Its calculation formula is as follows:
ΔE = (Δa2+Δb2+ΔL2)1/2 The color difference of color paste affects the accuracy of color mixing and the stability of color mixing formula.
In this regard, there are still some gaps between domestic and imported color paste, for example: Degussa’s Flexobrite c series factory color paste ΔE<0.6; COLORTREND 888 series mechanical color paste ΔE<0.5, at present, domestic color paste is generally not up to this level.
4、Light resistance and weather resistance of color paste
The test of the light and weather resistance of the color paste is through outdoor exposure (such as Florida in the United States, China’s Turpan and other places have exposure field), but the actual outdoor exposure time is too long, and now the general color paste performance testing is mostly through the simulation test of instruments and equipment. Light resistance test: Exposure under xenon light, measured by blue wool ruler, expressed as 1-8 level, level 8 is the best, level 1 is the worst.
Weathering resistance test: use ATLAS aging instrument, regularly exposed to xenon light and sprayed with water, exposed to 500 hours, color difference is expressed by ISO gray scale 1-5, grade 5 is the best, grade 1 is the worst. The color paste for exterior wall needs to be above light resistance grade 7 and weather resistance grade 4 at the same time.
5、Pigment content of color paste
The pigment content is only for reference and cannot be used as an indicator to evaluate the performance of the color paste. The coloring power of the color paste and the pigment content are not in a simple proportional relationship. The same pigment content, the fineness of different coloring power also has a great difference. In order to ensure the stability of the coloring power of the color paste, the pigment content of the color paste is within a certain range of the variation value, the value provided on the color paste information is a typical reference value.
6、Fineness of color paste
Fineness is an intuitive indicator to reflect the coloring power dispersion effect and storage stability of the color paste. Generally for the same pigment paste, the smaller the particle size, the larger the specific surface area, and thus the coverage capacity is increased, the higher the coloring power; the smaller the fineness, the higher the gloss, the better the dispersion effect and storage stability. Of course, the fineness of the color paste is not the finer the better, because when the particles become smaller, its specific surface area increases, the absorbed light energy increases, the degree of damage also increases, resulting in its weather resistance is reduced; and the particle size is too small in the coating film drying, with the precipitation of water, the color paste together to the surface migration, easy to cause inaccurate color matching and wall color difference.
7、Compatibility of color paste and paint
Finger research method to take 100 grams of white paint, add 2-3 grams of color paste to be tested, fully stirred, coated on the surface of the object to be coated, to be condensed, with a finger to grind the surface part of the coating film, to be dried after the film, observe the finger research rubbed and not research rubbed place whether there is a color difference, such as the difference is large, the color paste and the compatibility of the tested paint is not good, the color paste tuned out the paint is prone to floating color phenomenon. If the color is the same, generally will not produce floating color phenomenon.
When choosing the color paste should focus on the above factors, other conditions of each brand of color paste can basically reach and not much difference. Of course, when choosing the color paste should also be considered from the economic, environmental protection and other perspectives, such as: interior wall color paste can choose some poor weather resistance color paste, while the interior wall try not to choose chrome yellow and other heavy metals containing color paste, but should choose azo class, amine, etc.
