Pearlescent pigment is a kind of lustrous pigment: non-toxic, odorless, acid and alkali resistant, non-flammable, non-explosive, non-conductive, non-migrating, easy to disperse, high heat resistance and weather resistance, and fully meets strict environmental requirements. . The pearlescent pigment has the glittering effect of the metallic pigment, and can also produce the soft color of the natural pearl, and its glittering effect is passively illuminated, that is to say, the flashing effect is exhibited under the condition of receiving light.
The main types of pearlescent pigments are: natural fish scale pearlescent pigments, bismuth oxychloride crystal pearlescent pigments, and mica coated pearlescent pigments. At present, the most widely produced and widely used pearlescent pigments in the world are based on natural mica flakes (mica size from 4μm to 120μm and thickness of about 0.5μm), which is coated on the surface by special chemical processes. Multiple layers of titanium or other metal oxides. Image The metal oxide coated mica sheet provided by Basf Coatings Group is very smooth, so it has good light reflection properties and transparency, that is, only a part of the light is reflected, and the transmitted part of the light passes through the mica sheet to the other layer. It can continue to be fired, resulting in multiple reflections at many levels. It is difficult for the eye to focus on a certain layer and thereby establish the depth of the light.
So you can see a wonderfully deep, shiny sheen, which we call "Pearl." The flat flaky crystal should be the basic structural form of the pearlescent pigment. Only in this way can the pearlescent luster be strongly reflected like a lens, and the ratio of the diameter to thickness of the flat flaky crystal is preferably about 200, and the substance conforming to this condition Very rare. The higher the degree of parallel orientation of the flake pigment, the more obvious the pearl luster effect, and the pearlescent effect can be determined by the thickness of the titanium dioxide coating.
White pearlescence is formed by the reflection of the thinnest layer of titanium dioxide. As the thickness of the coating increases, the reflected light is white, yellow, gold, red, blue, and green, respectively. The iron oxide coating has the above properties in addition to its own color. Bronze is formed by the absorption of yellow color by ferric oxide, and the interference yellow is produced by the thickness of ferric oxide. With the same principle, you can get red and red. The color of the pearlescent pigment is related to the base color of the substrate. On a white substrate, transmitted light can be seen at any angle, and the interference color is not obvious. If the transmitted light is absorbed by the substrate on a black or dark substrate, the interference color is strong at the angle of reflection. The pearlescent pigment reflects light according to the specular effect, so the interference color can be seen at the reflection angle, and in the direction of the scattering angle, since the light is transmitted through the thin layer, the complementary color of the interference color can still be seen. For example, an interference red pearlescent pigment can be seen in the reflection angle to see red, while at the scattering angle it can be seen in green. The white pearlescent pigment is white at the reflection angle, and the scattering angle will reveal the color of the substrate or the color of the colorant. The color has a layered three-dimensional effect and different color effects due to different angles, making the pearlescent pigment different from some metallic pigments. Commonly used metallic pigments such as aluminum silver powder are opaque. The light is not transmissive, and all the light is reflected on the surface like a mirror surface, so it does not have the stereoscopic depth effect of the multilayer reflection of the pearlescent pigment. When a certain light absorbing pigment is added to the pearlescent pigment, since the pearlescent pigment itself is transparent, allowing light to penetrate and reach the light absorbing pigment, and then being reflected, the color of the light absorbing pigment is thereby enhanced and brighter. If a light-absorbing pigment is added to a metallic pigment, since the metallic pigment itself is opaque, light cannot pass through the metal sheet to reach the pigment, and thus the color is weakened. For example, aluminum powder, which is itself gray, the color of the light absorbing pigment thus becomes a dull gray, like a mud.
Metallic pigments are similar in shape and size to pearlescent pigments. The light is reflected by the specular principle, that is, the light is incident from a 45 degree angle and then reflected at a 45 degree angle. As the viewing angle increases, the reflected light is dimmed and the color is darkened. When you look at a pigment coating from a different angle, the color changes only in shades and does not have the same color change as pearlescent pigments. Pearlescent pigments cannot be mixed with conventional opaque pigments such as chromium, cadmium pigments, titanium dioxide. Ordinary metallic pigments and ordinary iron oxide pigments are light-scattering pigments, and their addition interferes with the light refraction of the pearlescent pigment due to light scattering, thereby reducing the pearlescent effect. Organic pigments with transparency and low hiding power, such as phthalocyanine blue, phthalocyanine green, etc., are mixed with pearlescent pigments, and have good pearlescent effect. Other transparent organic pigments such as light fast red, quinacridone, and permanent purple When used in combination with pearlescent pigments, the effect is also very good.
Carbon black and ultramarine in inorganic pigments are a special type. Although they are opaque and have high hiding power, they absorb all transmitted light and enhance the reflected light, so they can also be mixed with pearlescent pigments. And produces a bright additional color effect. As a special effect pigment, pearlescent pigments are used more and more in many industrial fields due to their unique and elegant luster, and the soft or flickering appearance caused by different colors and particle sizes. Due to the rapid growth of market demand, the supply market of pearlescent pigments has undergone very rapid changes, and this change will not stop but will intensify in the near future.
For the application of pearlescent pigments, it is necessary to timely and comprehensively examine the supply market situation, and accurately grasp the trend of future changes, not only to provide correct guidance for current procurement, but also to make forward-looking for future development. Prediction.