The application of colorants in water-based wood coatings and water-based industrial coatings is discussed

China Coatings Online News Information
Foreword
Anything that makes a substance appear and needs color for design is called a colorant, which can be organic or inorganic or naturally synthesized. The first colorants used by humans were minerals such as red hetero-iron ore (Fe2O3) and black magnetite (Fe3O4), which are easily obtained from nature and do not require complex treatment. The main mineral pigments in ancient China included hetero-iron ore, zhu sand, stone yellow, empty green, stone-green, hulk powder, ash, carbon black, etc.; When the red dye, because he had used up the pure potassium carbonate that should have been used as a raw material, he could only replace it with potassium carbonate mixed with animal oil impurities, but in this way, the red that should have been obtained unexpectedly turned purple and blue, which was the world's first chemically synthetic pigment, ushering in the era of modern colorants. The colorants used in coatings account for only a small part of the world's dye pigment varieties, and with the rapid development of water-based coatings, how to find and prepare more suitable for water-based systems colorants is the direction that paint color developers need to strive for.
1 Colorants in water-based wood coatings and water-based industrial coatings
1.1 Water-based chromosomal
1.1.1 color refinement introduction and classification
In coatings, the concentrated liquid of dyes is usually referred to as chromosomal, in this type of coloring and metallic complex dyes are the most widely used and mature. Metallic complex dye is a dye based on atom structure, which is formed by the mother dye and metal atom.
used in coatings are generally divided into three categories. The first category, is currently used in wood coatings the most extensive category, simple in the organic solvent-soluble metallic compound dye, this type of metallic ligand dye colored parts with anions, so generally it dissolves in the less polar solvent Less solubility, more solubility in solvents with higher polarity, such as BASF's Lissebao series is this category; Lily dyes, this type of metallic compound dye can be soluble in water, not in organic solvents; After the seasonal ammonium salt, inorge ions such as Na-plus and NH4-plus react instead, and the combined dye anion and the seasonal ammonium salt cation combine to form a compound with a smaller dissoluence, which reduces its polarity and increases the solubility in the solvent.
current paint coloring using different types of dye preparation according to the use of three categories. The first category is oily color essence, generally using DMF, acetone, butyl ketone, cyclosterone and other polar organic solvents as solvents, used in solvent-based coating systems; Water and oil-friendly properties, can be used in solvent-based coatings and water-based coatings, but also the current water-based system using the most ideal type of color, the third category is pure water-based color, mostly using acidic dyes or containing - SO3H and other water-soluble groups of metallic joint dye dissolved in water to prepare.
1.1.2 Metallic Hydration ColorIng
Metallic Hydration Dyes can be dissolved in environmentally friendly alcohol ether solvents to prepare water oil-based metallic Hydration Coloring, which is currently the most widely used one, due to stable metallic hydration dyes to ensure excellent resistance, in the color stability of coating products have been guaranteed. At the same time, the characteristics of hydro-oil of metallic hydrocolorics also improve their versatility and generality, making it more convenient for water-based coatings research and development and application workers to develop and use.
1.2 Water-based transparent slurry
1.2.1 water-based transparent iron oxide slurry
Water-based transparent iron oxide slurry is the use of dispersants and water to disperse iron oxide pigments for dispersion and grinding to obtain color slurry, which has a certain degree of transparency, mainly due to ultra-fine iron oxide α-FeOOH is a particle size of less than 100 nm pigment. Because of the small particle size, visible light bypasses these tiny particles in the process of propagation, and this diffraction makes the slurry made from the pigment transparent.
1.2.2 Water-transparent organic slurry
Water-transparent organic slurry, also known as ultra-dispersive water-transparent slurry, will be organic pigments such as pigment yellow PY83, pigment yellow PY1 10, pigment red PR146, pigment red PR256, carbon black, etc. through a special process to disperse grinding to pigment particles between the distance is less than 100 nm, at this time can also make the preparation of the color paste to achieve a transparent effect.
1.3 Water-based solid-color paste
1.3.1 Introduction to water-based solid-color plasma
Grinded pigment concentrate, generally this resin-free pigment concentration is high, strong coloring force, good color display performance, good compatible, with tact control fluidity, generally does not cause floating color and flowering.
1.3.2 Water-based solid color paste classification
At present, water-based solid color paste can be divided into inorganic color slurry and organic color paste according to pigment type, inorganic color slurry is mainly composed of titanium white, iron red, iron yellow, group green, iron black, carbon black, organic color paste mainly composed of organic red, organic yellow, indistinct blue, indistinct green and so on. According to the color slurry system can be divided into resin-free color slurry and resin-based color paste, resin-free system of color slurry has a high concentration, wide compatible characteristics, dispersant selection can effectively avoid floating hair flowers. The color slurry concentration with resin system is relatively low, the coating compatible is narrow, but the grinding is good with a higher gloss.
2 Performance characteristics of water-based wood coating colorants and their application
2.1 Application of colorants in water-based wood coating
2.1.1 Application of water-based coloring in wood coating
Wherein the color adjustment of the substrate is through the water-based color refinement with alcohol thinning or preparation of the fast-drying bottom color repair main agent to use, through the color fine dye evenly penetrates to the surface of the substrate to achieve the adjustment of the wood base color. The finished workmanage is adjusted by the addition of water-based color refinement to the alcohol-trimming main agent containing a small amount of resin, or by the water-based color refinement is applied to the modulated seepage main agent after 20 to 30min has been applied to the primer, and the dye molecule penetrates evenly into the paint to adjust the work piece color.
water-like color essence in wood coating in addition to the above two applications, for the work parts requirements are not high, the process is simple, you can also add water-like color refinement to the end of the paint or paint to adjust the color. Antique coating in the water-based color essence can also be added to Grace for coloring use, the same can achieve both the adjustment of the background color and highlight the effect of wood grain, but only applicable to the coating process is not long work, if encountered need for a long plate to wipe Grace, due to the dye penetration capacity is too strong and wipe Grace time is different, resulting in Grace stay time will be deep, Grace stay time will be shallow, the whole plate will not be uniform. So chromosomes are generally suitable for less-than-large work in antique Griss.
water-based color essence is also suitable for the same color paste for use, provided that the water-based color essence and water-based color paste in the Grace main agent compatible better, when the use of color essence and color paste with the bottom rub color substrate , after applying on the substrate, the permeability of the dye adjusts the color of the substrate, the pigment filling without permeability deepens the wood grain, which also simplifies the coating process, of course, the adjustment of the coloring substrate must be achieved to reduce burrs.
2.1.2 Application of water-based transparent color paste in wood coating
In wood coating both can be used in the Grice system, wherein transparent iron oxide color matching Grace color is darker, suitable for more dim antique, when the use of transparent iron oxide slurry for antique effect, if you need to improve the relative brightness need to use water-colored color to adjust the color. Transparent organic slurry by using organic pigments to resin as a connecting material prepared, with transparent iron oxide can not achieve the brightness and gloss, and because the pigment particle size is small has a certain permeability, so the use in the Gress can achieve both the adjustment of the color of the substrate and can be filled at the same time to deepen the wood grain purposes.
The author found through experiments, through the equal amount of water-based color essence, water-based iron oxide color paste, transparent organic color paste added to the equivalent Grace main agent in the coloring found that the highest color concentration is color essence, followed by transparent organic color paste, transparent iron oxide slurry is the darkest. The clearest highlight of the wood grain is the highly permeable organic paste, followed by the transparent iron oxide slurry, the color essence can not be very clearly filled and highlighted wood grain.
2.1.3 Application of water-based solid color paste in wood coating
For example, in colored putty and colored water ash, the choice of iron oxide system can make putty or water ash has a cost-effective. There are also the above mentioned wipe bottom color repair products, you can use color paste and color refinement to match to the color fixing substrate, you can also choose iron oxide series and water-based color fine with the use.
2.2 Performance characteristics of colorants applied to water-based wood coating
2.2.1 Performance characteristics of water-based coloring in wood coating
The following performance characteristics of color essence are mainly considered:
2.2.1.1 Storage stability of water-based color essence
Storage stability of good water-like color essence, the original liquid long-term storage will not appear hard precipitation. At the same time, water-based semen mucus will vary with the ambient temperature, due to solvent reasons, -10 degrees C will not crystallize, will only increase the viscosity but in the range of use, temperature increase viscosity recovery, so it can be applied to the cold environment in the north.
2.2.1.2 Resistance of water-based coloring to ultraviolet light
because water-based coloring is prepared using metallic ligation dyes, metallic lich dyes have excellent resistance to other dyes, especially UV resistance, and experimental tests have found that normal UV machine 10 times through and 4 min long-term exposure, metallic hydration color is only slightly changed.
2.2.1.3 Temperature resistance of water-based color essences
in metallic lying dyes, the resistance of large red, yellow and black to temperature is relatively high, 180 degrees C baking 30 min basic invarutable color, green and blue temperature resistance is relatively poor, 140 degrees C, 0.5 h has been slightly color change, so the water-based glass paint is not suitable.
2.2.1.4 Drying speed of hydrochromics
Depending on the drying speed of water-based coloring, choose suitable water-based systems, for example, in the system of fine-colored gold oil (face-repairing main agent), water-based coloring fine if dry slow or dry, need to increase resin Or the content of emulsion to improve the film after coating the resin-to-color essence of the package, to prevent the undried or dry color essence in the spraying of water-based paint when the upper dissolved migration resulting in flowering, oil shrinking, bottoming and other phenomena, at the same time, the process is required to fully dry the finished coating film. If the water-based color essence is relatively dry faster some systems with relatively few alternative resins, in order to achieve rapid color repair and rapid painting purposes.
2.2.1.5 Environmental protection of water-based coloring
Secondly, the heavy metals used in the metal bond dye should meet the requirements of EN17-3.
2.2.2 Performance characteristics of water-based transparent slurry in wood coating


The transparency of transparent color paste is the premise guarantee of its special use, the experiment found that in organic transparent color paste, PR146, PR254, PY83, PY110 pigment treatment and grinding is good, its transparency and color contrast is not too big, indistinct blue and indistinct green and color essence transparency is equivalent. Transparent iron oxide is a little worse transparent.
2.2.2.2 Coloring force of water-based transparent slurry
Water-transparent slurry is used in wood coating to consider its coloring force, such as the same transparent iron oxide slurry and transparent organic slurry added to Grace, the experiment found that 10% of the transparent organic slurry added amount of coloring strength can be equivalent to 20% transparent iron oxide pigment addition.
2.2.2.3 Compatible with water-based transparent color paste
whether water-based transparent iron oxide slurry or water-based organic transparent slurry is a system that mainly takes water as a dispersion medium, this stable equal phase needs to take into account the rebalancing of the mixture when mixing with other systems, such as transparent slurry added to a large amount of alcohol, alcohol will destroy the transparent slurry system, pigment particle accumulation. Therefore, when adding transparent color paste to the color repair system, its compatible should be taken into account.
2.2.2.4 Weather resistance of water-based transparent color paste
Whether transparent iron oxide or transparent organic slurry, due to the use of pigment preparation, its weather resistance is excellent, especially in organic transparent color paste PR254 red, PY110 yellow, can be used in water-based UV coatings.
2.2.3 Performance characteristics of water-based solid color paste in wood coating

2.3.1 Storage stability of water-like solid color paste
Storage stability of water-like solid-colored slurry is related to abrasive particle size, system viscosity, additive anti-sinking, pigment proportion and other factors. Inorger series of large proportions, dispersant selection and system viscosity adjustment is more important, anti-sinking effect of the color paste will appear hard subsidon for a long time, not easy to use.
2.2.3.2 pH of water-based color paste
the pH of water-based slurry without resin system should be adjusted to about 9 is better, first of all