Pearlescent pigment matching with high transparency ink or varnish

Since the unique luster and color of pearlescent pigments are completely dependent on the reflection and transmission of light, any factor that weakens or hinders the reflection and transmission of such light, such as scattering properties, crystals, and heterophasic polymer systems With equal dispersion, it will be difficult for the pearlescent effect of the final product to be fully exhibited. In general, the transparency of the ink or varnish increases the pearling effect of the final product. The use of less transparent ink varnish, the pearl effect is poor.

The concentration of pearlescent pigments also has stringent requirements for carrier inks. In general, we recommend the use of pearlescent pigments at a concentration of 10% to 20:6 (the total weight ratio of the ink). In most cases, a concentration of 12% to 15% can achieve the desired pearlescent effect. To achieve a good pearlescent effect, it is also required that the pearlescent pigment carrier ink be as transparent as possible. The color of the ink itself also directly affects the pearlescent effect. If the ink color is yellow or not clear, the pearlescent effect after printing is not ideal and the surface is yellow. The key is to make the pearl ink and ink cartridges soluble.

Pearlescent pigments and other pigments

Pearlescent pigments can be mixed with transparent pigments to make the product more natural, more vivid and more attractive. For example, phthalocyanine blue and phthalocyanine green with high transparency, low hiding power, and high transparency of organic pigments such as sunrays, quinacridones, and permanent violet are ideal for color reproduction. Stable organic dyes can also be blended with pearlescent pigments with satisfactory results. When mixed with opaque (strong hiding power) pigments such as common metallic pigments, titanium white pigments, iron red, and yellow iron, the pearl pigments will be lost due to the hiding and scattering of light by the covering pigments. Unique hue and luster. When it is necessary to add a masking material, the addition amount should be as small as possible, usually not exceeding 0.1% of the pigment.

Some pearlescent pigments can also be blended with carbon black and ultramarine blue. Although they are opaque and have a high hiding power, they absorb all transmitted light from the pearlescent pigments, which in turn allows the reflected light to be strengthened, resulting in not only a final pearlescent effect. , while producing additional color effects. Such as silver white pearlescent pigment mixed with carbon black, there will be a metallic silver gray, while improving the hiding power. The blackness value can be adjusted by changing the amount of carbon black to achieve satisfactory results. When the golden series of pearlescent pigments is mixed with carbon black, a deep metallic tone can be created. If the golden pearlescent pigments are mixed with carbon black, they will show a deep bronze color.

Pearlescent pigment dispersion

The unique hue, pearl and metallic luster of the pearlescent pigments on the final printed product mostly depend on whether the pearlescent pigments can be uniformly dispersed and arranged in parallel (see Figure 1).

When formulating pearlescent inks, pearlescent pigments should be added at the final stage of blending, ie, when all the other components have been mixed evenly before they are added. This prevents the pearlescent pigments from being damaged by excessive shearing. In the production process, pearlescent inks are often formulated using a pre-dispersed method. The method is: first wet the pearlescent pigment with a small amount of solvent, then add a small amount of the carrier ink and stir evenly, and finally add the concentrate to the remaining ink for further stirring and dispersion. Stirring should be done with a low-shear high-speed stirrer. It takes about 15 minutes to ensure even dispersion. In order to prevent the pigment flakes from being damaged, high-shear stirring devices such as ball mills, stone mills and three-rollers should be avoided.

Low viscosity pearlescent or pearlescent coatings are prone to delamination or precipitation. When used, it should be stirred in time to prevent precipitation and affect product quality.

The reappearance of the pearlescent effect depends to a large extent on the thickness of the ink film. The thickness of the ink film and the large-particle pearlescent pigment can be found in the ink film in a large amount. At this time, the pearlescent effect is apparent. Therefore, try to ensure that the amount of ink is as large as possible during printing. In printing, large printing pressures and low nano-printing speeds should be used as much as possible. These conditions can make the ink output during printing large, and the ink film thickness of the printed products is relatively thick, so that the printed products have a good pearlescent effect. .